Commit | Line | Data |
---|---|---|
b8d4c8d0 GM |
1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
acaf905b | 3 | @c Copyright (C) 1990-1995, 1998-1999, 2001-2012 |
d24880de | 4 | @c Free Software Foundation, Inc. |
b8d4c8d0 | 5 | @c See the file elisp.texi for copying conditions. |
ecc6530d | 6 | @node Processes |
b8d4c8d0 GM |
7 | @chapter Processes |
8 | @cindex child process | |
9 | @cindex parent process | |
10 | @cindex subprocess | |
11 | @cindex process | |
12 | ||
13 | In the terminology of operating systems, a @dfn{process} is a space in | |
14 | which a program can execute. Emacs runs in a process. Emacs Lisp | |
15 | programs can invoke other programs in processes of their own. These are | |
16 | called @dfn{subprocesses} or @dfn{child processes} of the Emacs process, | |
17 | which is their @dfn{parent process}. | |
18 | ||
19 | A subprocess of Emacs may be @dfn{synchronous} or @dfn{asynchronous}, | |
20 | depending on how it is created. When you create a synchronous | |
21 | subprocess, the Lisp program waits for the subprocess to terminate | |
22 | before continuing execution. When you create an asynchronous | |
23 | subprocess, it can run in parallel with the Lisp program. This kind of | |
24 | subprocess is represented within Emacs by a Lisp object which is also | |
e153c136 | 25 | called a ``process''. Lisp programs can use this object to communicate |
b8d4c8d0 GM |
26 | with the subprocess or to control it. For example, you can send |
27 | signals, obtain status information, receive output from the process, or | |
28 | send input to it. | |
29 | ||
30 | @defun processp object | |
23dd4ecd EZ |
31 | This function returns @code{t} if @var{object} represents an Emacs |
32 | subprocess, @code{nil} otherwise. | |
b8d4c8d0 GM |
33 | @end defun |
34 | ||
23dd4ecd EZ |
35 | In addition to subprocesses of the current Emacs session, you can |
36 | also access other processes running on your machine. @xref{System | |
37 | Processes}. | |
38 | ||
b8d4c8d0 GM |
39 | @menu |
40 | * Subprocess Creation:: Functions that start subprocesses. | |
41 | * Shell Arguments:: Quoting an argument to pass it to a shell. | |
42 | * Synchronous Processes:: Details of using synchronous subprocesses. | |
43 | * Asynchronous Processes:: Starting up an asynchronous subprocess. | |
44 | * Deleting Processes:: Eliminating an asynchronous subprocess. | |
45 | * Process Information:: Accessing run-status and other attributes. | |
46 | * Input to Processes:: Sending input to an asynchronous subprocess. | |
47 | * Signals to Processes:: Stopping, continuing or interrupting | |
48 | an asynchronous subprocess. | |
49 | * Output from Processes:: Collecting output from an asynchronous subprocess. | |
50 | * Sentinels:: Sentinels run when process run-status changes. | |
51 | * Query Before Exit:: Whether to query if exiting will kill a process. | |
23dd4ecd | 52 | * System Processes:: Accessing other processes running on your system. |
d24880de | 53 | * Transaction Queues:: Transaction-based communication with subprocesses. |
b8d4c8d0 GM |
54 | * Network:: Opening network connections. |
55 | * Network Servers:: Network servers let Emacs accept net connections. | |
56 | * Datagrams:: UDP network connections. | |
57 | * Low-Level Network:: Lower-level but more general function | |
58 | to create connections and servers. | |
d24880de | 59 | * Misc Network:: Additional relevant functions for net connections. |
c73e02fa | 60 | * Serial Ports:: Communicating with serial ports. |
b8d4c8d0 GM |
61 | * Byte Packing:: Using bindat to pack and unpack binary data. |
62 | @end menu | |
63 | ||
64 | @node Subprocess Creation | |
65 | @section Functions that Create Subprocesses | |
66 | ||
583d8b3c | 67 | There are three primitives that create a new subprocess in which to run |
b8d4c8d0 GM |
68 | a program. One of them, @code{start-process}, creates an asynchronous |
69 | process and returns a process object (@pxref{Asynchronous Processes}). | |
70 | The other two, @code{call-process} and @code{call-process-region}, | |
71 | create a synchronous process and do not return a process object | |
e153c136 GM |
72 | (@pxref{Synchronous Processes}). There are various higher-level |
73 | functions that make use of these primitives to run particular types of | |
74 | process. | |
b8d4c8d0 GM |
75 | |
76 | Synchronous and asynchronous processes are explained in the following | |
77 | sections. Since the three functions are all called in a similar | |
78 | fashion, their common arguments are described here. | |
79 | ||
80 | @cindex execute program | |
8fc85b20 GM |
81 | @cindex @env{PATH} environment variable |
82 | @cindex @env{HOME} environment variable | |
b8d4c8d0 GM |
83 | In all cases, the function's @var{program} argument specifies the |
84 | program to be run. An error is signaled if the file is not found or | |
85 | cannot be executed. If the file name is relative, the variable | |
86 | @code{exec-path} contains a list of directories to search. Emacs | |
87 | initializes @code{exec-path} when it starts up, based on the value of | |
8fc85b20 | 88 | the environment variable @env{PATH}. The standard file name |
b8d4c8d0 GM |
89 | constructs, @samp{~}, @samp{.}, and @samp{..}, are interpreted as |
90 | usual in @code{exec-path}, but environment variable substitutions | |
91 | (@samp{$HOME}, etc.) are not recognized; use | |
92 | @code{substitute-in-file-name} to perform them (@pxref{File Name | |
93 | Expansion}). @code{nil} in this list refers to | |
94 | @code{default-directory}. | |
95 | ||
96 | Executing a program can also try adding suffixes to the specified | |
97 | name: | |
98 | ||
2bc356d7 | 99 | @defopt exec-suffixes |
b8d4c8d0 GM |
100 | This variable is a list of suffixes (strings) to try adding to the |
101 | specified program file name. The list should include @code{""} if you | |
102 | want the name to be tried exactly as specified. The default value is | |
103 | system-dependent. | |
2bc356d7 | 104 | @end defopt |
b8d4c8d0 GM |
105 | |
106 | @strong{Please note:} The argument @var{program} contains only the | |
107 | name of the program; it may not contain any command-line arguments. You | |
e153c136 GM |
108 | must use a separate argument, @var{args}, to provide those, as |
109 | described below. | |
b8d4c8d0 GM |
110 | |
111 | Each of the subprocess-creating functions has a @var{buffer-or-name} | |
e153c136 | 112 | argument that specifies where the standard output from the program will |
b8d4c8d0 GM |
113 | go. It should be a buffer or a buffer name; if it is a buffer name, |
114 | that will create the buffer if it does not already exist. It can also | |
115 | be @code{nil}, which says to discard the output unless a filter function | |
116 | handles it. (@xref{Filter Functions}, and @ref{Read and Print}.) | |
117 | Normally, you should avoid having multiple processes send output to the | |
118 | same buffer because their output would be intermixed randomly. | |
e153c136 GM |
119 | For synchronous processes, you can send the output to a file instead |
120 | of a buffer. | |
b8d4c8d0 GM |
121 | |
122 | @cindex program arguments | |
123 | All three of the subprocess-creating functions have a @code{&rest} | |
124 | argument, @var{args}. The @var{args} must all be strings, and they are | |
125 | supplied to @var{program} as separate command line arguments. Wildcard | |
126 | characters and other shell constructs have no special meanings in these | |
127 | strings, since the strings are passed directly to the specified program. | |
128 | ||
b8d4c8d0 GM |
129 | @cindex environment variables, subprocesses |
130 | The subprocess inherits its environment from Emacs, but you can | |
131 | specify overrides for it with @code{process-environment}. @xref{System | |
e153c136 GM |
132 | Environment}. The subprocess gets its current directory from the |
133 | value of @code{default-directory}. | |
b8d4c8d0 GM |
134 | |
135 | @defvar exec-directory | |
136 | @pindex movemail | |
137 | The value of this variable is a string, the name of a directory that | |
e153c136 | 138 | contains programs that come with GNU Emacs and are intended for Emacs |
b8d4c8d0 GM |
139 | to invoke. The program @code{movemail} is an example of such a program; |
140 | Rmail uses it to fetch new mail from an inbox. | |
141 | @end defvar | |
142 | ||
143 | @defopt exec-path | |
144 | The value of this variable is a list of directories to search for | |
145 | programs to run in subprocesses. Each element is either the name of a | |
146 | directory (i.e., a string), or @code{nil}, which stands for the default | |
147 | directory (which is the value of @code{default-directory}). | |
148 | @cindex program directories | |
149 | ||
150 | The value of @code{exec-path} is used by @code{call-process} and | |
151 | @code{start-process} when the @var{program} argument is not an absolute | |
152 | file name. | |
e153c136 GM |
153 | |
154 | Generally, you should not modify @code{exec-path} directly. Instead, | |
155 | ensure that your @env{PATH} environment variable is set appropriately | |
156 | before starting Emacs. Trying to modify @code{exec-path} | |
157 | independently of @env{PATH} can lead to confusing results. | |
b8d4c8d0 GM |
158 | @end defopt |
159 | ||
160 | @node Shell Arguments | |
161 | @section Shell Arguments | |
162 | @cindex arguments for shell commands | |
163 | @cindex shell command arguments | |
164 | ||
165 | Lisp programs sometimes need to run a shell and give it a command | |
166 | that contains file names that were specified by the user. These | |
167 | programs ought to be able to support any valid file name. But the shell | |
168 | gives special treatment to certain characters, and if these characters | |
169 | occur in the file name, they will confuse the shell. To handle these | |
170 | characters, use the function @code{shell-quote-argument}: | |
171 | ||
172 | @defun shell-quote-argument argument | |
e153c136 | 173 | This function returns a string that represents, in shell syntax, |
b8d4c8d0 GM |
174 | an argument whose actual contents are @var{argument}. It should |
175 | work reliably to concatenate the return value into a shell command | |
176 | and then pass it to a shell for execution. | |
177 | ||
178 | Precisely what this function does depends on your operating system. The | |
179 | function is designed to work with the syntax of your system's standard | |
180 | shell; if you use an unusual shell, you will need to redefine this | |
181 | function. | |
182 | ||
183 | @example | |
184 | ;; @r{This example shows the behavior on GNU and Unix systems.} | |
185 | (shell-quote-argument "foo > bar") | |
186 | @result{} "foo\\ \\>\\ bar" | |
187 | ||
188 | ;; @r{This example shows the behavior on MS-DOS and MS-Windows.} | |
189 | (shell-quote-argument "foo > bar") | |
190 | @result{} "\"foo > bar\"" | |
191 | @end example | |
192 | ||
193 | Here's an example of using @code{shell-quote-argument} to construct | |
194 | a shell command: | |
195 | ||
196 | @example | |
197 | (concat "diff -c " | |
198 | (shell-quote-argument oldfile) | |
199 | " " | |
200 | (shell-quote-argument newfile)) | |
201 | @end example | |
202 | @end defun | |
203 | ||
3c73e30e EZ |
204 | @cindex quoting and unquoting command-line arguments |
205 | @cindex minibuffer input, and command-line arguments | |
206 | @cindex @code{call-process}, command-line arguments from minibuffer | |
207 | @cindex @code{start-process}, command-line arguments from minibuffer | |
4bb49a92 EZ |
208 | The following two functions are useful for combining a list of |
209 | individual command-line argument strings into a single string, and | |
210 | taking a string apart into a list of individual command-line | |
e153c136 | 211 | arguments. These functions are mainly intended for |
4bb49a92 EZ |
212 | converting user input in the minibuffer, a Lisp string, into a list of |
213 | string arguments to be passed to @code{call-process} or | |
e153c136 | 214 | @code{start-process}, or for converting such lists of arguments into |
3c73e30e | 215 | a single Lisp string to be presented in the minibuffer or echo area. |
a873ee3d EZ |
216 | |
217 | @defun split-string-and-unquote string &optional separators | |
218 | This function splits @var{string} into substrings at matches for the | |
219 | regular expression @var{separators}, like @code{split-string} does | |
0999039c CY |
220 | (@pxref{Creating Strings}); in addition, it removes quoting from the |
221 | substrings. It then makes a list of the substrings and returns it. | |
a873ee3d | 222 | |
4185820c CY |
223 | If @var{separators} is omitted or @code{nil}, it defaults to |
224 | @code{"\\s-+"}, which is a regular expression that matches one or more | |
225 | characters with whitespace syntax (@pxref{Syntax Class Table}). | |
a873ee3d | 226 | |
3c73e30e | 227 | This function supports two types of quoting: enclosing a whole string |
0999039c CY |
228 | in double quotes @code{"@dots{}"}, and quoting individual characters |
229 | with a backslash escape @samp{\}. The latter is also used in Lisp | |
230 | strings, so this function can handle those as well. | |
a873ee3d EZ |
231 | @end defun |
232 | ||
233 | @defun combine-and-quote-strings list-of-strings &optional separator | |
234 | This function concatenates @var{list-of-strings} into a single string, | |
0999039c CY |
235 | quoting each string as necessary. It also sticks the @var{separator} |
236 | string between each pair of strings; if @var{separator} is omitted or | |
237 | @code{nil}, it defaults to @code{" "}. The return value is the | |
238 | resulting string. | |
a873ee3d EZ |
239 | |
240 | The strings in @var{list-of-strings} that need quoting are those that | |
241 | include @var{separator} as their substring. Quoting a string encloses | |
242 | it in double quotes @code{"@dots{}"}. In the simplest case, if you | |
4bb49a92 EZ |
243 | are consing a command from the individual command-line arguments, |
244 | every argument that includes embedded blanks will be quoted. | |
a873ee3d EZ |
245 | @end defun |
246 | ||
b8d4c8d0 GM |
247 | @node Synchronous Processes |
248 | @section Creating a Synchronous Process | |
249 | @cindex synchronous subprocess | |
250 | ||
251 | After a @dfn{synchronous process} is created, Emacs waits for the | |
252 | process to terminate before continuing. Starting Dired on GNU or | |
253 | Unix@footnote{On other systems, Emacs uses a Lisp emulation of | |
254 | @code{ls}; see @ref{Contents of Directories}.} is an example of this: it | |
255 | runs @code{ls} in a synchronous process, then modifies the output | |
256 | slightly. Because the process is synchronous, the entire directory | |
257 | listing arrives in the buffer before Emacs tries to do anything with it. | |
258 | ||
259 | While Emacs waits for the synchronous subprocess to terminate, the | |
260 | user can quit by typing @kbd{C-g}. The first @kbd{C-g} tries to kill | |
261 | the subprocess with a @code{SIGINT} signal; but it waits until the | |
262 | subprocess actually terminates before quitting. If during that time the | |
263 | user types another @kbd{C-g}, that kills the subprocess instantly with | |
264 | @code{SIGKILL} and quits immediately (except on MS-DOS, where killing | |
265 | other processes doesn't work). @xref{Quitting}. | |
266 | ||
267 | The synchronous subprocess functions return an indication of how the | |
268 | process terminated. | |
269 | ||
270 | The output from a synchronous subprocess is generally decoded using a | |
271 | coding system, much like text read from a file. The input sent to a | |
272 | subprocess by @code{call-process-region} is encoded using a coding | |
273 | system, much like text written into a file. @xref{Coding Systems}. | |
274 | ||
275 | @defun call-process program &optional infile destination display &rest args | |
b59a4335 | 276 | This function calls @var{program} and waits for it to finish. |
b8d4c8d0 | 277 | |
0a6dd5e2 JA |
278 | The current working directory of the subprocess is |
279 | @code{default-directory}. | |
280 | ||
b59a4335 | 281 | The standard input for the new process comes from file @var{infile} if |
b8d4c8d0 GM |
282 | @var{infile} is not @code{nil}, and from the null device otherwise. |
283 | The argument @var{destination} says where to put the process output. | |
284 | Here are the possibilities: | |
285 | ||
286 | @table @asis | |
287 | @item a buffer | |
288 | Insert the output in that buffer, before point. This includes both the | |
289 | standard output stream and the standard error stream of the process. | |
290 | ||
291 | @item a string | |
292 | Insert the output in a buffer with that name, before point. | |
293 | ||
294 | @item @code{t} | |
295 | Insert the output in the current buffer, before point. | |
296 | ||
297 | @item @code{nil} | |
298 | Discard the output. | |
299 | ||
300 | @item 0 | |
301 | Discard the output, and return @code{nil} immediately without waiting | |
302 | for the subprocess to finish. | |
303 | ||
304 | In this case, the process is not truly synchronous, since it can run in | |
305 | parallel with Emacs; but you can think of it as synchronous in that | |
306 | Emacs is essentially finished with the subprocess as soon as this | |
307 | function returns. | |
308 | ||
309 | MS-DOS doesn't support asynchronous subprocesses, so this option doesn't | |
310 | work there. | |
311 | ||
1ef14cb4 | 312 | @item @code{(:file @var{file-name})} |
1b9f60cc GM |
313 | Send the output to the file name specified, overwriting it if it |
314 | already exists. | |
1ef14cb4 | 315 | |
b8d4c8d0 GM |
316 | @item @code{(@var{real-destination} @var{error-destination})} |
317 | Keep the standard output stream separate from the standard error stream; | |
318 | deal with the ordinary output as specified by @var{real-destination}, | |
319 | and dispose of the error output according to @var{error-destination}. | |
320 | If @var{error-destination} is @code{nil}, that means to discard the | |
321 | error output, @code{t} means mix it with the ordinary output, and a | |
322 | string specifies a file name to redirect error output into. | |
323 | ||
324 | You can't directly specify a buffer to put the error output in; that is | |
325 | too difficult to implement. But you can achieve this result by sending | |
326 | the error output to a temporary file and then inserting the file into a | |
327 | buffer. | |
328 | @end table | |
329 | ||
330 | If @var{display} is non-@code{nil}, then @code{call-process} redisplays | |
331 | the buffer as output is inserted. (However, if the coding system chosen | |
332 | for decoding output is @code{undecided}, meaning deduce the encoding | |
333 | from the actual data, then redisplay sometimes cannot continue once | |
334 | non-@acronym{ASCII} characters are encountered. There are fundamental | |
335 | reasons why it is hard to fix this; see @ref{Output from Processes}.) | |
336 | ||
337 | Otherwise the function @code{call-process} does no redisplay, and the | |
338 | results become visible on the screen only when Emacs redisplays that | |
339 | buffer in the normal course of events. | |
340 | ||
341 | The remaining arguments, @var{args}, are strings that specify command | |
342 | line arguments for the program. | |
343 | ||
344 | The value returned by @code{call-process} (unless you told it not to | |
345 | wait) indicates the reason for process termination. A number gives the | |
346 | exit status of the subprocess; 0 means success, and any other value | |
347 | means failure. If the process terminated with a signal, | |
348 | @code{call-process} returns a string describing the signal. | |
349 | ||
350 | In the examples below, the buffer @samp{foo} is current. | |
351 | ||
352 | @smallexample | |
353 | @group | |
354 | (call-process "pwd" nil t) | |
355 | @result{} 0 | |
356 | ||
357 | ---------- Buffer: foo ---------- | |
e153c136 | 358 | /home/lewis/manual |
b8d4c8d0 GM |
359 | ---------- Buffer: foo ---------- |
360 | @end group | |
361 | ||
362 | @group | |
363 | (call-process "grep" nil "bar" nil "lewis" "/etc/passwd") | |
364 | @result{} 0 | |
365 | ||
366 | ---------- Buffer: bar ---------- | |
e153c136 | 367 | lewis:x:1001:1001:Bil Lewis,,,,:/home/lewis:/bin/bash |
b8d4c8d0 GM |
368 | |
369 | ---------- Buffer: bar ---------- | |
370 | @end group | |
371 | @end smallexample | |
372 | ||
e153c136 GM |
373 | Here is an example of the use of @code{call-process}, as used to |
374 | be found in the definition of the @code{insert-directory} function: | |
b8d4c8d0 GM |
375 | |
376 | @smallexample | |
377 | @group | |
e153c136 | 378 | (call-process insert-directory-program nil t nil switches |
b8d4c8d0 GM |
379 | (if full-directory-p |
380 | (concat (file-name-as-directory file) ".") | |
381 | file)) | |
382 | @end group | |
383 | @end smallexample | |
384 | @end defun | |
385 | ||
386 | @defun process-file program &optional infile buffer display &rest args | |
387 | This function processes files synchronously in a separate process. It | |
e153c136 GM |
388 | is similar to @code{call-process}, but may invoke a file handler based |
389 | on the value of the variable @code{default-directory}, which specifies | |
390 | the current working directory of the subprocess. | |
b8d4c8d0 GM |
391 | |
392 | The arguments are handled in almost the same way as for | |
393 | @code{call-process}, with the following differences: | |
394 | ||
395 | Some file handlers may not support all combinations and forms of the | |
396 | arguments @var{infile}, @var{buffer}, and @var{display}. For example, | |
397 | some file handlers might behave as if @var{display} were @code{nil}, | |
398 | regardless of the value actually passed. As another example, some | |
399 | file handlers might not support separating standard output and error | |
400 | output by way of the @var{buffer} argument. | |
401 | ||
402 | If a file handler is invoked, it determines the program to run based | |
e153c136 | 403 | on the first argument @var{program}. For instance, suppose that a |
b8d4c8d0 | 404 | handler for remote files is invoked. Then the path that is used for |
e153c136 | 405 | searching for the program might be different from @code{exec-path}. |
b8d4c8d0 GM |
406 | |
407 | The second argument @var{infile} may invoke a file handler. The file | |
408 | handler could be different from the handler chosen for the | |
409 | @code{process-file} function itself. (For example, | |
e153c136 GM |
410 | @code{default-directory} could be on one remote host, and |
411 | @var{infile} on a different remote host. Or @code{default-directory} | |
b8d4c8d0 GM |
412 | could be non-special, whereas @var{infile} is on a remote host.) |
413 | ||
414 | If @var{buffer} is a list of the form @code{(@var{real-destination} | |
415 | @var{error-destination})}, and @var{error-destination} names a file, | |
416 | then the same remarks as for @var{infile} apply. | |
417 | ||
418 | The remaining arguments (@var{args}) will be passed to the process | |
419 | verbatim. Emacs is not involved in processing file names that are | |
420 | present in @var{args}. To avoid confusion, it may be best to avoid | |
421 | absolute file names in @var{args}, but rather to specify all file | |
422 | names as relative to @code{default-directory}. The function | |
423 | @code{file-relative-name} is useful for constructing such relative | |
424 | file names. | |
425 | @end defun | |
426 | ||
3691a0a6 | 427 | @defvar process-file-side-effects |
e153c136 | 428 | This variable indicates whether a call of @code{process-file} changes |
3691a0a6 MA |
429 | remote files. |
430 | ||
e153c136 | 431 | By default, this variable is always set to @code{t}, meaning that a |
3691a0a6 MA |
432 | call of @code{process-file} could potentially change any file on a |
433 | remote host. When set to @code{nil}, a file handler could optimize | |
e153c136 | 434 | its behavior with respect to remote file attribute caching. |
3691a0a6 | 435 | |
e153c136 GM |
436 | You should only ever change this variable with a let-binding; never |
437 | with @code{setq}. | |
3691a0a6 MA |
438 | @end defvar |
439 | ||
b8d4c8d0 GM |
440 | @defun call-process-region start end program &optional delete destination display &rest args |
441 | This function sends the text from @var{start} to @var{end} as | |
442 | standard input to a process running @var{program}. It deletes the text | |
443 | sent if @var{delete} is non-@code{nil}; this is useful when | |
444 | @var{destination} is @code{t}, to insert the output in the current | |
445 | buffer in place of the input. | |
446 | ||
447 | The arguments @var{destination} and @var{display} control what to do | |
448 | with the output from the subprocess, and whether to update the display | |
449 | as it comes in. For details, see the description of | |
450 | @code{call-process}, above. If @var{destination} is the integer 0, | |
451 | @code{call-process-region} discards the output and returns @code{nil} | |
452 | immediately, without waiting for the subprocess to finish (this only | |
e153c136 | 453 | works if asynchronous subprocesses are supported; i.e. not on MS-DOS). |
b8d4c8d0 GM |
454 | |
455 | The remaining arguments, @var{args}, are strings that specify command | |
456 | line arguments for the program. | |
457 | ||
458 | The return value of @code{call-process-region} is just like that of | |
459 | @code{call-process}: @code{nil} if you told it to return without | |
460 | waiting; otherwise, a number or string which indicates how the | |
461 | subprocess terminated. | |
462 | ||
463 | In the following example, we use @code{call-process-region} to run the | |
464 | @code{cat} utility, with standard input being the first five characters | |
465 | in buffer @samp{foo} (the word @samp{input}). @code{cat} copies its | |
466 | standard input into its standard output. Since the argument | |
467 | @var{destination} is @code{t}, this output is inserted in the current | |
468 | buffer. | |
469 | ||
470 | @smallexample | |
471 | @group | |
472 | ---------- Buffer: foo ---------- | |
473 | input@point{} | |
474 | ---------- Buffer: foo ---------- | |
475 | @end group | |
476 | ||
477 | @group | |
478 | (call-process-region 1 6 "cat" nil t) | |
479 | @result{} 0 | |
480 | ||
481 | ---------- Buffer: foo ---------- | |
482 | inputinput@point{} | |
483 | ---------- Buffer: foo ---------- | |
484 | @end group | |
485 | @end smallexample | |
486 | ||
e153c136 GM |
487 | For example, the @code{shell-command-on-region} command uses |
488 | @code{call-process-region} in a manner similar to this: | |
b8d4c8d0 GM |
489 | |
490 | @smallexample | |
491 | @group | |
492 | (call-process-region | |
493 | start end | |
e153c136 GM |
494 | shell-file-name ; @r{name of program} |
495 | nil ; @r{do not delete region} | |
496 | buffer ; @r{send output to @code{buffer}} | |
497 | nil ; @r{no redisplay during output} | |
498 | "-c" command) ; @r{arguments for the shell} | |
b8d4c8d0 GM |
499 | @end group |
500 | @end smallexample | |
12acf783 | 501 | @c It actually uses shell-command-switch, but no need to mention that here. |
b8d4c8d0 GM |
502 | @end defun |
503 | ||
504 | @defun call-process-shell-command command &optional infile destination display &rest args | |
b59a4335 CY |
505 | This function executes the shell command @var{command} synchronously. |
506 | The final arguments @var{args} are additional arguments to add at the | |
507 | end of @var{command}. The other arguments are handled as in | |
508 | @code{call-process}. | |
b8d4c8d0 GM |
509 | @end defun |
510 | ||
511 | @defun process-file-shell-command command &optional infile destination display &rest args | |
512 | This function is like @code{call-process-shell-command}, but uses | |
513 | @code{process-file} internally. Depending on @code{default-directory}, | |
514 | @var{command} can be executed also on remote hosts. | |
515 | @end defun | |
516 | ||
517 | @defun shell-command-to-string command | |
518 | This function executes @var{command} (a string) as a shell command, | |
519 | then returns the command's output as a string. | |
520 | @end defun | |
521 | ||
e153c136 GM |
522 | @c There is also shell-command-on-region, but that is more of a user |
523 | @c command, not something to use in programs. | |
524 | ||
583d8b3c | 525 | @defun process-lines program &rest args |
b59a4335 CY |
526 | This function runs @var{program}, waits for it to finish, and returns |
527 | its output as a list of strings. Each string in the list holds a | |
528 | single line of text output by the program; the end-of-line characters | |
529 | are stripped from each line. The arguments beyond @var{program}, | |
530 | @var{args}, are strings that specify command-line arguments with which | |
531 | to run the program. | |
583d8b3c EZ |
532 | |
533 | If @var{program} exits with a non-zero exit status, this function | |
534 | signals an error. | |
535 | ||
536 | This function works by calling @code{call-process}, so program output | |
537 | is decoded in the same way as for @code{call-process}. | |
538 | @end defun | |
539 | ||
b8d4c8d0 GM |
540 | @node Asynchronous Processes |
541 | @section Creating an Asynchronous Process | |
542 | @cindex asynchronous subprocess | |
543 | ||
6d41a41d TTN |
544 | In this section, we describe how to create an @dfn{asynchronous |
545 | process}. After an asynchronous process is created, it runs in | |
546 | parallel with Emacs, and Emacs can communicate with it using the | |
547 | functions described in the following sections (@pxref{Input to | |
548 | Processes}, and @pxref{Output from Processes}). Note that process | |
b8d4c8d0 GM |
549 | communication is only partially asynchronous: Emacs sends data to the |
550 | process only when certain functions are called, and Emacs accepts data | |
6d41a41d TTN |
551 | from the process only while waiting for input or for a time delay. |
552 | ||
553 | @cindex pty | |
554 | @cindex pipe | |
555 | An asynchronous process is controlled either via a @dfn{pty} | |
556 | (pseudo-terminal) or a @dfn{pipe}. The choice of pty or pipe is made | |
557 | when creating the process, based on the value of the variable | |
558 | @code{process-connection-type} (see below). Ptys are usually | |
559 | preferable for processes visible to the user, as in Shell mode, | |
560 | because they allow for job control (@kbd{C-c}, @kbd{C-z}, etc.) | |
561 | between the process and its children, whereas pipes do not. For | |
562 | subprocesses used for internal purposes by programs, it is often | |
563 | better to use a pipe, because they are more efficient, and because | |
564 | they are immune to stray character injections that ptys introduce for | |
565 | large (around 500 byte) messages. Also, the total number of ptys is | |
566 | limited on many systems and it is good not to waste them. | |
b8d4c8d0 GM |
567 | |
568 | @defun start-process name buffer-or-name program &rest args | |
569 | This function creates a new asynchronous subprocess and starts the | |
570 | program @var{program} running in it. It returns a process object that | |
571 | stands for the new subprocess in Lisp. The argument @var{name} | |
572 | specifies the name for the process object; if a process with this name | |
573 | already exists, then @var{name} is modified (by appending @samp{<1>}, | |
574 | etc.) to be unique. The buffer @var{buffer-or-name} is the buffer to | |
575 | associate with the process. | |
576 | ||
f30d612a CY |
577 | If @var{program} is @code{nil}, Emacs opens a new pseudoterminal (pty) |
578 | and associates its input and output with @var{buffer-or-name}, without | |
579 | creating a subprocess. In that case, the remaining arguments | |
580 | @var{args} are ignored. | |
581 | ||
b8d4c8d0 | 582 | The remaining arguments, @var{args}, are strings that specify command |
f30d612a | 583 | line arguments for the subprocess. |
b8d4c8d0 GM |
584 | |
585 | In the example below, the first process is started and runs (rather, | |
12acf783 GM |
586 | sleeps) for 100 seconds (the output buffer @samp{foo} is created |
587 | immediately). Meanwhile, the second process is started, and | |
b8d4c8d0 GM |
588 | given the name @samp{my-process<1>} for the sake of uniqueness. It |
589 | inserts the directory listing at the end of the buffer @samp{foo}, | |
590 | before the first process finishes. Then it finishes, and a message to | |
591 | that effect is inserted in the buffer. Much later, the first process | |
592 | finishes, and another message is inserted in the buffer for it. | |
593 | ||
594 | @smallexample | |
595 | @group | |
596 | (start-process "my-process" "foo" "sleep" "100") | |
597 | @result{} #<process my-process> | |
598 | @end group | |
599 | ||
600 | @group | |
12acf783 | 601 | (start-process "my-process" "foo" "ls" "-l" "/bin") |
b8d4c8d0 GM |
602 | @result{} #<process my-process<1>> |
603 | ||
604 | ---------- Buffer: foo ---------- | |
12acf783 GM |
605 | total 8336 |
606 | -rwxr-xr-x 1 root root 971384 Mar 30 10:14 bash | |
607 | -rwxr-xr-x 1 root root 146920 Jul 5 2011 bsd-csh | |
608 | @dots{} | |
609 | -rwxr-xr-x 1 root root 696880 Feb 28 15:55 zsh4 | |
b8d4c8d0 GM |
610 | |
611 | Process my-process<1> finished | |
612 | ||
613 | Process my-process finished | |
614 | ---------- Buffer: foo ---------- | |
615 | @end group | |
616 | @end smallexample | |
617 | @end defun | |
618 | ||
619 | @defun start-file-process name buffer-or-name program &rest args | |
620 | Like @code{start-process}, this function starts a new asynchronous | |
621 | subprocess running @var{program} in it, and returns its process | |
12acf783 | 622 | object. |
b8d4c8d0 | 623 | |
12acf783 GM |
624 | The difference from @code{start-process} is that this function may |
625 | invoked a file handler based on the value of @code{default-directory}. | |
626 | This handler ought to run @var{program}, perhaps on the local host, | |
627 | perhaps on a remote host that corresponds to @code{default-directory}. | |
628 | In the latter case, the local part of @code{default-directory} becomes | |
629 | the working directory of the process. | |
b8d4c8d0 GM |
630 | |
631 | This function does not try to invoke file name handlers for | |
632 | @var{program} or for the @var{program-args}. | |
633 | ||
634 | Depending on the implementation of the file handler, it might not be | |
635 | possible to apply @code{process-filter} or @code{process-sentinel} to | |
12acf783 | 636 | the resulting process object. @xref{Filter Functions}, and @ref{Sentinels}. |
b8d4c8d0 | 637 | |
12acf783 GM |
638 | @c FIXME Can we find a better example (i.e. a more modern function |
639 | @c that is actually documented). | |
b8d4c8d0 | 640 | Some file handlers may not support @code{start-file-process} (for |
12acf783 GM |
641 | example the function @code{ange-ftp-hook-function}). In such cases, |
642 | this function does nothing and returns @code{nil}. | |
b8d4c8d0 GM |
643 | @end defun |
644 | ||
03a74b84 | 645 | @defun start-process-shell-command name buffer-or-name command |
12acf783 | 646 | This function is like @code{start-process}, except that it uses a shell |
b8d4c8d0 | 647 | to execute the specified command. The argument @var{command} is a shell |
03a74b84 | 648 | command name. The variable @code{shell-file-name} specifies which shell to |
b8d4c8d0 GM |
649 | use. |
650 | ||
651 | The point of running a program through the shell, rather than directly | |
652 | with @code{start-process}, is so that you can employ shell features such | |
12acf783 GM |
653 | as wildcards in the arguments. It follows that if you include any |
654 | arbitrary user-specified arguments in the command, you should quote them | |
b8d4c8d0 GM |
655 | with @code{shell-quote-argument} first, so that any special shell |
656 | characters do @emph{not} have their special shell meanings. @xref{Shell | |
12acf783 GM |
657 | Arguments}. Of course, when executing commands based on user input |
658 | you should also consider the security implications. | |
b8d4c8d0 GM |
659 | @end defun |
660 | ||
03a74b84 | 661 | @defun start-file-process-shell-command name buffer-or-name command |
b8d4c8d0 | 662 | This function is like @code{start-process-shell-command}, but uses |
12acf783 GM |
663 | @code{start-file-process} internally. Because of this, @var{command} |
664 | can also be executed on remote hosts, depending on @code{default-directory}. | |
b8d4c8d0 GM |
665 | @end defun |
666 | ||
667 | @defvar process-connection-type | |
b8d4c8d0 | 668 | This variable controls the type of device used to communicate with |
a2eb421b | 669 | asynchronous subprocesses. If it is non-@code{nil}, then ptys are |
b8d4c8d0 GM |
670 | used, when available. Otherwise, pipes are used. |
671 | ||
b8d4c8d0 GM |
672 | The value of @code{process-connection-type} takes effect when |
673 | @code{start-process} is called. So you can specify how to communicate | |
674 | with one subprocess by binding the variable around the call to | |
675 | @code{start-process}. | |
676 | ||
677 | @smallexample | |
678 | @group | |
12acf783 | 679 | (let ((process-connection-type nil)) ; @r{use a pipe} |
b8d4c8d0 GM |
680 | (start-process @dots{})) |
681 | @end group | |
682 | @end smallexample | |
683 | ||
a2eb421b CY |
684 | To determine whether a given subprocess actually got a pipe or a pty, |
685 | use the function @code{process-tty-name} (@pxref{Process | |
b8d4c8d0 GM |
686 | Information}). |
687 | @end defvar | |
688 | ||
689 | @node Deleting Processes | |
690 | @section Deleting Processes | |
691 | @cindex deleting processes | |
692 | ||
693 | @dfn{Deleting a process} disconnects Emacs immediately from the | |
694 | subprocess. Processes are deleted automatically after they terminate, | |
695 | but not necessarily right away. You can delete a process explicitly | |
12acf783 | 696 | at any time. If you explicitly delete a terminated process before it |
b8d4c8d0 | 697 | is deleted automatically, no harm results. Deleting a running |
12acf783 | 698 | process sends a signal to terminate it (and its child processes, if |
b8d4c8d0 GM |
699 | any), and calls the process sentinel if it has one. @xref{Sentinels}. |
700 | ||
701 | When a process is deleted, the process object itself continues to | |
702 | exist as long as other Lisp objects point to it. All the Lisp | |
703 | primitives that work on process objects accept deleted processes, but | |
704 | those that do I/O or send signals will report an error. The process | |
705 | mark continues to point to the same place as before, usually into a | |
706 | buffer where output from the process was being inserted. | |
707 | ||
708 | @defopt delete-exited-processes | |
709 | This variable controls automatic deletion of processes that have | |
710 | terminated (due to calling @code{exit} or to a signal). If it is | |
711 | @code{nil}, then they continue to exist until the user runs | |
712 | @code{list-processes}. Otherwise, they are deleted immediately after | |
713 | they exit. | |
714 | @end defopt | |
715 | ||
716 | @defun delete-process process | |
717 | This function deletes a process, killing it with a @code{SIGKILL} | |
718 | signal. The argument may be a process, the name of a process, a | |
719 | buffer, or the name of a buffer. (A buffer or buffer-name stands for | |
720 | the process that @code{get-buffer-process} returns.) Calling | |
721 | @code{delete-process} on a running process terminates it, updates the | |
722 | process status, and runs the sentinel (if any) immediately. If the | |
723 | process has already terminated, calling @code{delete-process} has no | |
724 | effect on its status, or on the running of its sentinel (which will | |
725 | happen sooner or later). | |
726 | ||
727 | @smallexample | |
728 | @group | |
729 | (delete-process "*shell*") | |
730 | @result{} nil | |
731 | @end group | |
732 | @end smallexample | |
733 | @end defun | |
734 | ||
735 | @node Process Information | |
736 | @section Process Information | |
737 | ||
738 | Several functions return information about processes. | |
b8d4c8d0 | 739 | |
62f4b18c | 740 | @deffn Command list-processes &optional query-only buffer |
b8d4c8d0 GM |
741 | This command displays a listing of all living processes. In addition, |
742 | it finally deletes any process whose status was @samp{Exited} or | |
743 | @samp{Signaled}. It returns @code{nil}. | |
744 | ||
62f4b18c GM |
745 | The processes are shown in a buffer named @file{*Process List*} |
746 | (unless you specify otherwise using the optional argument @var{buffer}), | |
747 | whose major mode is Process Menu mode. | |
82233bea | 748 | |
62f4b18c | 749 | If @var{query-only} is non-@code{nil}, it only lists processes |
b8d4c8d0 GM |
750 | whose query flag is non-@code{nil}. @xref{Query Before Exit}. |
751 | @end deffn | |
752 | ||
753 | @defun process-list | |
754 | This function returns a list of all processes that have not been deleted. | |
755 | ||
756 | @smallexample | |
757 | @group | |
758 | (process-list) | |
759 | @result{} (#<process display-time> #<process shell>) | |
760 | @end group | |
761 | @end smallexample | |
762 | @end defun | |
763 | ||
764 | @defun get-process name | |
62f4b18c GM |
765 | This function returns the process named @var{name} (a string), or |
766 | @code{nil} if there is none. | |
b8d4c8d0 GM |
767 | |
768 | @smallexample | |
769 | @group | |
770 | (get-process "shell") | |
771 | @result{} #<process shell> | |
772 | @end group | |
773 | @end smallexample | |
774 | @end defun | |
775 | ||
776 | @defun process-command process | |
777 | This function returns the command that was executed to start | |
778 | @var{process}. This is a list of strings, the first string being the | |
779 | program executed and the rest of the strings being the arguments that | |
780 | were given to the program. | |
781 | ||
782 | @smallexample | |
783 | @group | |
784 | (process-command (get-process "shell")) | |
62f4b18c | 785 | @result{} ("bash" "-i") |
b8d4c8d0 GM |
786 | @end group |
787 | @end smallexample | |
788 | @end defun | |
789 | ||
c73e02fa GM |
790 | @defun process-contact process &optional key |
791 | ||
792 | This function returns information about how a network or serial | |
62f4b18c GM |
793 | process was set up. When @var{key} is @code{nil}, it returns |
794 | @code{(@var{hostname} @var{service})} for a network process, and | |
795 | @code{(@var{port} @var{speed})} for a serial process. | |
796 | For an ordinary child process, this function always returns @code{t}. | |
c73e02fa GM |
797 | |
798 | If @var{key} is @code{t}, the value is the complete status information | |
799 | for the connection, server, or serial port; that is, the list of | |
800 | keywords and values specified in @code{make-network-process} or | |
801 | @code{make-serial-process}, except that some of the values represent | |
802 | the current status instead of what you specified. | |
803 | ||
62f4b18c GM |
804 | For a network process, the values include (see |
805 | @code{make-network-process} for a complete list): | |
c73e02fa GM |
806 | |
807 | @table @code | |
808 | @item :buffer | |
809 | The associated value is the process buffer. | |
810 | @item :filter | |
811 | The associated value is the process filter function. | |
812 | @item :sentinel | |
813 | The associated value is the process sentinel function. | |
814 | @item :remote | |
815 | In a connection, the address in internal format of the remote peer. | |
816 | @item :local | |
817 | The local address, in internal format. | |
818 | @item :service | |
819 | In a server, if you specified @code{t} for @var{service}, | |
820 | this value is the actual port number. | |
821 | @end table | |
822 | ||
823 | @code{:local} and @code{:remote} are included even if they were not | |
824 | specified explicitly in @code{make-network-process}. | |
825 | ||
826 | For a serial process, see @code{make-serial-process} and | |
827 | @code{serial-process-configure} for a list of keys. | |
828 | ||
829 | If @var{key} is a keyword, the function returns the value corresponding | |
830 | to that keyword. | |
831 | @end defun | |
832 | ||
b8d4c8d0 GM |
833 | @defun process-id process |
834 | This function returns the @acronym{PID} of @var{process}. This is an | |
835 | integer that distinguishes the process @var{process} from all other | |
836 | processes running on the same computer at the current time. The | |
837 | @acronym{PID} of a process is chosen by the operating system kernel when the | |
838 | process is started and remains constant as long as the process exists. | |
839 | @end defun | |
840 | ||
841 | @defun process-name process | |
62f4b18c | 842 | This function returns the name of @var{process}, as a string. |
b8d4c8d0 GM |
843 | @end defun |
844 | ||
845 | @defun process-status process-name | |
846 | This function returns the status of @var{process-name} as a symbol. | |
170ddd97 CY |
847 | The argument @var{process-name} must be a process, a buffer, or a |
848 | process name (a string). | |
b8d4c8d0 GM |
849 | |
850 | The possible values for an actual subprocess are: | |
851 | ||
852 | @table @code | |
853 | @item run | |
854 | for a process that is running. | |
855 | @item stop | |
856 | for a process that is stopped but continuable. | |
857 | @item exit | |
858 | for a process that has exited. | |
859 | @item signal | |
860 | for a process that has received a fatal signal. | |
861 | @item open | |
862 | for a network connection that is open. | |
863 | @item closed | |
864 | for a network connection that is closed. Once a connection | |
865 | is closed, you cannot reopen it, though you might be able to open | |
866 | a new connection to the same place. | |
867 | @item connect | |
868 | for a non-blocking connection that is waiting to complete. | |
869 | @item failed | |
870 | for a non-blocking connection that has failed to complete. | |
871 | @item listen | |
872 | for a network server that is listening. | |
873 | @item nil | |
874 | if @var{process-name} is not the name of an existing process. | |
875 | @end table | |
876 | ||
877 | @smallexample | |
878 | @group | |
b8d4c8d0 GM |
879 | (process-status (get-buffer "*shell*")) |
880 | @result{} run | |
881 | @end group | |
b8d4c8d0 GM |
882 | @end smallexample |
883 | ||
884 | For a network connection, @code{process-status} returns one of the symbols | |
885 | @code{open} or @code{closed}. The latter means that the other side | |
886 | closed the connection, or Emacs did @code{delete-process}. | |
887 | @end defun | |
888 | ||
b96e6cde | 889 | @defun process-live-p process |
e153c136 | 890 | This function returns non-@code{nil} if @var{process} is alive. A |
bcd54f83 LMI |
891 | process is considered alive if its status is @code{run}, @code{open}, |
892 | @code{listen}, @code{connect} or @code{stop}. | |
893 | @end defun | |
894 | ||
c73e02fa GM |
895 | @defun process-type process |
896 | This function returns the symbol @code{network} for a network | |
897 | connection or server, @code{serial} for a serial port connection, or | |
898 | @code{real} for a real subprocess. | |
899 | @end defun | |
900 | ||
b8d4c8d0 GM |
901 | @defun process-exit-status process |
902 | This function returns the exit status of @var{process} or the signal | |
903 | number that killed it. (Use the result of @code{process-status} to | |
904 | determine which of those it is.) If @var{process} has not yet | |
905 | terminated, the value is 0. | |
906 | @end defun | |
907 | ||
908 | @defun process-tty-name process | |
909 | This function returns the terminal name that @var{process} is using for | |
910 | its communication with Emacs---or @code{nil} if it is using pipes | |
911 | instead of a terminal (see @code{process-connection-type} in | |
bace45fe MA |
912 | @ref{Asynchronous Processes}). If @var{process} represents a program |
913 | running on a remote host, the terminal name used by that program on | |
914 | the remote host is provided as process property @code{remote-tty}. | |
b8d4c8d0 GM |
915 | @end defun |
916 | ||
917 | @defun process-coding-system process | |
918 | @anchor{Coding systems for a subprocess} | |
62f4b18c GM |
919 | This function returns a cons cell @code{(@var{decode} . @var{encode})}, |
920 | describing the coding systems in use for decoding output from, and | |
921 | encoding input to, @var{process} (@pxref{Coding Systems}). | |
b8d4c8d0 GM |
922 | @end defun |
923 | ||
924 | @defun set-process-coding-system process &optional decoding-system encoding-system | |
925 | This function specifies the coding systems to use for subsequent output | |
926 | from and input to @var{process}. It will use @var{decoding-system} to | |
927 | decode subprocess output, and @var{encoding-system} to encode subprocess | |
928 | input. | |
929 | @end defun | |
930 | ||
931 | Every process also has a property list that you can use to store | |
932 | miscellaneous values associated with the process. | |
933 | ||
934 | @defun process-get process propname | |
935 | This function returns the value of the @var{propname} property | |
936 | of @var{process}. | |
937 | @end defun | |
938 | ||
939 | @defun process-put process propname value | |
940 | This function sets the value of the @var{propname} property | |
941 | of @var{process} to @var{value}. | |
942 | @end defun | |
943 | ||
944 | @defun process-plist process | |
945 | This function returns the process plist of @var{process}. | |
946 | @end defun | |
947 | ||
948 | @defun set-process-plist process plist | |
949 | This function sets the process plist of @var{process} to @var{plist}. | |
950 | @end defun | |
951 | ||
952 | @node Input to Processes | |
953 | @section Sending Input to Processes | |
954 | @cindex process input | |
955 | ||
956 | Asynchronous subprocesses receive input when it is sent to them by | |
957 | Emacs, which is done with the functions in this section. You must | |
958 | specify the process to send input to, and the input data to send. The | |
959 | data appears on the ``standard input'' of the subprocess. | |
960 | ||
62f4b18c | 961 | @c FIXME which? |
b8d4c8d0 | 962 | Some operating systems have limited space for buffered input in a |
a2eb421b CY |
963 | pty. On these systems, Emacs sends an @acronym{EOF} periodically |
964 | amidst the other characters, to force them through. For most | |
965 | programs, these @acronym{EOF}s do no harm. | |
b8d4c8d0 GM |
966 | |
967 | Subprocess input is normally encoded using a coding system before the | |
968 | subprocess receives it, much like text written into a file. You can use | |
969 | @code{set-process-coding-system} to specify which coding system to use | |
970 | (@pxref{Process Information}). Otherwise, the coding system comes from | |
971 | @code{coding-system-for-write}, if that is non-@code{nil}; or else from | |
972 | the defaulting mechanism (@pxref{Default Coding Systems}). | |
973 | ||
974 | Sometimes the system is unable to accept input for that process, | |
975 | because the input buffer is full. When this happens, the send functions | |
976 | wait a short while, accepting output from subprocesses, and then try | |
977 | again. This gives the subprocess a chance to read more of its pending | |
978 | input and make space in the buffer. It also allows filters, sentinels | |
979 | and timers to run---so take account of that in writing your code. | |
980 | ||
981 | In these functions, the @var{process} argument can be a process or | |
982 | the name of a process, or a buffer or buffer name (which stands | |
983 | for a process via @code{get-buffer-process}). @code{nil} means | |
984 | the current buffer's process. | |
985 | ||
986 | @defun process-send-string process string | |
987 | This function sends @var{process} the contents of @var{string} as | |
62f4b18c GM |
988 | standard input. It returns @code{nil}. For example, to make a |
989 | Shell buffer list files: | |
b8d4c8d0 GM |
990 | |
991 | @smallexample | |
992 | @group | |
993 | (process-send-string "shell<1>" "ls\n") | |
994 | @result{} nil | |
995 | @end group | |
b8d4c8d0 GM |
996 | @end smallexample |
997 | @end defun | |
998 | ||
999 | @defun process-send-region process start end | |
1000 | This function sends the text in the region defined by @var{start} and | |
1001 | @var{end} as standard input to @var{process}. | |
1002 | ||
1003 | An error is signaled unless both @var{start} and @var{end} are | |
1004 | integers or markers that indicate positions in the current buffer. (It | |
1005 | is unimportant which number is larger.) | |
1006 | @end defun | |
1007 | ||
1008 | @defun process-send-eof &optional process | |
1009 | This function makes @var{process} see an end-of-file in its | |
1010 | input. The @acronym{EOF} comes after any text already sent to it. | |
b8d4c8d0 GM |
1011 | The function returns @var{process}. |
1012 | ||
1013 | @smallexample | |
1014 | @group | |
1015 | (process-send-eof "shell") | |
1016 | @result{} "shell" | |
1017 | @end group | |
1018 | @end smallexample | |
1019 | @end defun | |
1020 | ||
106e6894 CY |
1021 | @defun process-running-child-p &optional process |
1022 | This function will tell you whether a @var{process} has given control of | |
b8d4c8d0 GM |
1023 | its terminal to its own child process. The value is @code{t} if this is |
1024 | true, or if Emacs cannot tell; it is @code{nil} if Emacs can be certain | |
1025 | that this is not so. | |
1026 | @end defun | |
1027 | ||
1028 | @node Signals to Processes | |
1029 | @section Sending Signals to Processes | |
1030 | @cindex process signals | |
1031 | @cindex sending signals | |
1032 | @cindex signals | |
1033 | ||
1034 | @dfn{Sending a signal} to a subprocess is a way of interrupting its | |
1035 | activities. There are several different signals, each with its own | |
1036 | meaning. The set of signals and their names is defined by the operating | |
1037 | system. For example, the signal @code{SIGINT} means that the user has | |
1038 | typed @kbd{C-c}, or that some analogous thing has happened. | |
1039 | ||
1040 | Each signal has a standard effect on the subprocess. Most signals | |
62f4b18c | 1041 | kill the subprocess, but some stop (or resume) execution instead. Most |
b8d4c8d0 GM |
1042 | signals can optionally be handled by programs; if the program handles |
1043 | the signal, then we can say nothing in general about its effects. | |
1044 | ||
1045 | You can send signals explicitly by calling the functions in this | |
1046 | section. Emacs also sends signals automatically at certain times: | |
1047 | killing a buffer sends a @code{SIGHUP} signal to all its associated | |
1048 | processes; killing Emacs sends a @code{SIGHUP} signal to all remaining | |
1049 | processes. (@code{SIGHUP} is a signal that usually indicates that the | |
62f4b18c | 1050 | user ``hung up the phone'', i.e., disconnected.) |
b8d4c8d0 GM |
1051 | |
1052 | Each of the signal-sending functions takes two optional arguments: | |
1053 | @var{process} and @var{current-group}. | |
1054 | ||
1055 | The argument @var{process} must be either a process, a process | |
1056 | name, a buffer, a buffer name, or @code{nil}. A buffer or buffer name | |
1057 | stands for a process through @code{get-buffer-process}. @code{nil} | |
1058 | stands for the process associated with the current buffer. An error | |
1059 | is signaled if @var{process} does not identify a process. | |
1060 | ||
1061 | The argument @var{current-group} is a flag that makes a difference | |
1062 | when you are running a job-control shell as an Emacs subprocess. If it | |
1063 | is non-@code{nil}, then the signal is sent to the current process-group | |
1064 | of the terminal that Emacs uses to communicate with the subprocess. If | |
1065 | the process is a job-control shell, this means the shell's current | |
1066 | subjob. If it is @code{nil}, the signal is sent to the process group of | |
1067 | the immediate subprocess of Emacs. If the subprocess is a job-control | |
1068 | shell, this is the shell itself. | |
1069 | ||
1070 | The flag @var{current-group} has no effect when a pipe is used to | |
1071 | communicate with the subprocess, because the operating system does not | |
1072 | support the distinction in the case of pipes. For the same reason, | |
1073 | job-control shells won't work when a pipe is used. See | |
1074 | @code{process-connection-type} in @ref{Asynchronous Processes}. | |
1075 | ||
1076 | @defun interrupt-process &optional process current-group | |
1077 | This function interrupts the process @var{process} by sending the | |
1078 | signal @code{SIGINT}. Outside of Emacs, typing the ``interrupt | |
0b128ac4 | 1079 | character'' (normally @kbd{C-c} on some systems, and @key{DEL} on |
b8d4c8d0 GM |
1080 | others) sends this signal. When the argument @var{current-group} is |
1081 | non-@code{nil}, you can think of this function as ``typing @kbd{C-c}'' | |
1082 | on the terminal by which Emacs talks to the subprocess. | |
1083 | @end defun | |
1084 | ||
1085 | @defun kill-process &optional process current-group | |
1086 | This function kills the process @var{process} by sending the | |
1087 | signal @code{SIGKILL}. This signal kills the subprocess immediately, | |
1088 | and cannot be handled by the subprocess. | |
1089 | @end defun | |
1090 | ||
1091 | @defun quit-process &optional process current-group | |
1092 | This function sends the signal @code{SIGQUIT} to the process | |
1093 | @var{process}. This signal is the one sent by the ``quit | |
62f4b18c GM |
1094 | @c FIXME? Never heard of C-b being used for this. In readline, eg |
1095 | @c bash, that is backward-word. | |
b8d4c8d0 GM |
1096 | character'' (usually @kbd{C-b} or @kbd{C-\}) when you are not inside |
1097 | Emacs. | |
1098 | @end defun | |
1099 | ||
1100 | @defun stop-process &optional process current-group | |
1101 | This function stops the process @var{process} by sending the | |
1102 | signal @code{SIGTSTP}. Use @code{continue-process} to resume its | |
1103 | execution. | |
1104 | ||
1105 | Outside of Emacs, on systems with job control, the ``stop character'' | |
1106 | (usually @kbd{C-z}) normally sends this signal. When | |
1107 | @var{current-group} is non-@code{nil}, you can think of this function as | |
1108 | ``typing @kbd{C-z}'' on the terminal Emacs uses to communicate with the | |
1109 | subprocess. | |
1110 | @end defun | |
1111 | ||
1112 | @defun continue-process &optional process current-group | |
1113 | This function resumes execution of the process @var{process} by sending | |
1114 | it the signal @code{SIGCONT}. This presumes that @var{process} was | |
1115 | stopped previously. | |
1116 | @end defun | |
1117 | ||
0b128ac4 | 1118 | @deffn Command signal-process process signal |
b8d4c8d0 | 1119 | This function sends a signal to process @var{process}. The argument |
62f4b18c GM |
1120 | @var{signal} specifies which signal to send; it should be an integer, |
1121 | or a symbol whose name is a signal. | |
b8d4c8d0 | 1122 | |
62f4b18c GM |
1123 | The @var{process} argument can be a system process @acronym{ID} (an |
1124 | integer); that allows you to send signals to processes that are not | |
1125 | children of Emacs. @xref{System Processes}. | |
0b128ac4 | 1126 | @end deffn |
b8d4c8d0 GM |
1127 | |
1128 | @node Output from Processes | |
1129 | @section Receiving Output from Processes | |
1130 | @cindex process output | |
1131 | @cindex output from processes | |
1132 | ||
1133 | There are two ways to receive the output that a subprocess writes to | |
1134 | its standard output stream. The output can be inserted in a buffer, | |
62f4b18c GM |
1135 | which is called the associated buffer of the process (@pxref{Process |
1136 | Buffers}), or a function called the @dfn{filter function} can be | |
1137 | called to act on the output. If the process has no buffer and no | |
1138 | filter function, its output is discarded. | |
b8d4c8d0 GM |
1139 | |
1140 | When a subprocess terminates, Emacs reads any pending output, | |
1141 | then stops reading output from that subprocess. Therefore, if the | |
1142 | subprocess has children that are still live and still producing | |
1143 | output, Emacs won't receive that output. | |
1144 | ||
1145 | Output from a subprocess can arrive only while Emacs is waiting: when | |
016a35df GM |
1146 | reading terminal input (see the function @code{waiting-for-user-input-p}), |
1147 | in @code{sit-for} and @code{sleep-for} (@pxref{Waiting}), and in | |
1148 | @code{accept-process-output} (@pxref{Accepting Output}). This | |
1149 | minimizes the problem of timing errors that usually plague parallel | |
1150 | programming. For example, you can safely create a process and only | |
1151 | then specify its buffer or filter function; no output can arrive | |
1152 | before you finish, if the code in between does not call any primitive | |
1153 | that waits. | |
b8d4c8d0 GM |
1154 | |
1155 | @defvar process-adaptive-read-buffering | |
1156 | On some systems, when Emacs reads the output from a subprocess, the | |
1157 | output data is read in very small blocks, potentially resulting in | |
1158 | very poor performance. This behavior can be remedied to some extent | |
62f4b18c | 1159 | by setting the variable @code{process-adaptive-read-buffering} to a |
b8d4c8d0 GM |
1160 | non-@code{nil} value (the default), as it will automatically delay reading |
1161 | from such processes, thus allowing them to produce more output before | |
1162 | Emacs tries to read it. | |
1163 | @end defvar | |
1164 | ||
1165 | It is impossible to separate the standard output and standard error | |
1166 | streams of the subprocess, because Emacs normally spawns the subprocess | |
1167 | inside a pseudo-TTY, and a pseudo-TTY has only one output channel. If | |
1168 | you want to keep the output to those streams separate, you should | |
1169 | redirect one of them to a file---for example, by using an appropriate | |
1170 | shell command. | |
1171 | ||
1172 | @menu | |
1173 | * Process Buffers:: If no filter, output is put in a buffer. | |
1174 | * Filter Functions:: Filter functions accept output from the process. | |
1175 | * Decoding Output:: Filters can get unibyte or multibyte strings. | |
1176 | * Accepting Output:: How to wait until process output arrives. | |
1177 | @end menu | |
1178 | ||
1179 | @node Process Buffers | |
1180 | @subsection Process Buffers | |
1181 | ||
1182 | A process can (and usually does) have an @dfn{associated buffer}, | |
1183 | which is an ordinary Emacs buffer that is used for two purposes: storing | |
1184 | the output from the process, and deciding when to kill the process. You | |
1185 | can also use the buffer to identify a process to operate on, since in | |
1186 | normal practice only one process is associated with any given buffer. | |
1187 | Many applications of processes also use the buffer for editing input to | |
1188 | be sent to the process, but this is not built into Emacs Lisp. | |
1189 | ||
1190 | Unless the process has a filter function (@pxref{Filter Functions}), | |
1191 | its output is inserted in the associated buffer. The position to insert | |
1192 | the output is determined by the @code{process-mark}, which is then | |
1193 | updated to point to the end of the text just inserted. Usually, but not | |
1194 | always, the @code{process-mark} is at the end of the buffer. | |
1195 | ||
16d1ff5f CY |
1196 | @findex process-kill-buffer-query-function |
1197 | Killing the associated buffer of a process also kills the process. | |
1198 | Emacs asks for confirmation first, if the process's | |
1199 | @code{process-query-on-exit-flag} is non-@code{nil} (@pxref{Query | |
1200 | Before Exit}). This confirmation is done by the function | |
1201 | @code{process-kill-buffer-query-function}, which is run from | |
1202 | @code{kill-buffer-query-functions} (@pxref{Killing Buffers}). | |
1203 | ||
b8d4c8d0 GM |
1204 | @defun process-buffer process |
1205 | This function returns the associated buffer of the process | |
1206 | @var{process}. | |
1207 | ||
1208 | @smallexample | |
1209 | @group | |
1210 | (process-buffer (get-process "shell")) | |
1211 | @result{} #<buffer *shell*> | |
1212 | @end group | |
1213 | @end smallexample | |
1214 | @end defun | |
1215 | ||
1216 | @defun process-mark process | |
1217 | This function returns the process marker for @var{process}, which is the | |
1218 | marker that says where to insert output from the process. | |
1219 | ||
1220 | If @var{process} does not have a buffer, @code{process-mark} returns a | |
1221 | marker that points nowhere. | |
1222 | ||
1223 | Insertion of process output in a buffer uses this marker to decide where | |
1224 | to insert, and updates it to point after the inserted text. That is why | |
1225 | successive batches of output are inserted consecutively. | |
1226 | ||
1227 | Filter functions normally should use this marker in the same fashion | |
62f4b18c GM |
1228 | as is done by direct insertion of output in the buffer. For an |
1229 | example of a filter function that uses @code{process-mark}, | |
1230 | @pxref{Process Filter Example}. | |
b8d4c8d0 GM |
1231 | |
1232 | When the user is expected to enter input in the process buffer for | |
1233 | transmission to the process, the process marker separates the new input | |
1234 | from previous output. | |
1235 | @end defun | |
1236 | ||
1237 | @defun set-process-buffer process buffer | |
1238 | This function sets the buffer associated with @var{process} to | |
1239 | @var{buffer}. If @var{buffer} is @code{nil}, the process becomes | |
1240 | associated with no buffer. | |
1241 | @end defun | |
1242 | ||
1243 | @defun get-buffer-process buffer-or-name | |
1244 | This function returns a nondeleted process associated with the buffer | |
1245 | specified by @var{buffer-or-name}. If there are several processes | |
1246 | associated with it, this function chooses one (currently, the one most | |
1247 | recently created, but don't count on that). Deletion of a process | |
1248 | (see @code{delete-process}) makes it ineligible for this function to | |
1249 | return. | |
1250 | ||
1251 | It is usually a bad idea to have more than one process associated with | |
1252 | the same buffer. | |
1253 | ||
1254 | @smallexample | |
1255 | @group | |
1256 | (get-buffer-process "*shell*") | |
1257 | @result{} #<process shell> | |
1258 | @end group | |
1259 | @end smallexample | |
1260 | ||
1261 | Killing the process's buffer deletes the process, which kills the | |
1262 | subprocess with a @code{SIGHUP} signal (@pxref{Signals to Processes}). | |
1263 | @end defun | |
1264 | ||
1265 | @node Filter Functions | |
1266 | @subsection Process Filter Functions | |
1267 | @cindex filter function | |
1268 | @cindex process filter | |
1269 | ||
1270 | A process @dfn{filter function} is a function that receives the | |
1271 | standard output from the associated process. If a process has a filter, | |
1272 | then @emph{all} output from that process is passed to the filter. The | |
1273 | process buffer is used directly for output from the process only when | |
1274 | there is no filter. | |
1275 | ||
1276 | The filter function can only be called when Emacs is waiting for | |
1277 | something, because process output arrives only at such times. Emacs | |
016a35df GM |
1278 | waits when reading terminal input (see the function |
1279 | @code{waiting-for-user-input-p}), in @code{sit-for} and | |
1280 | @code{sleep-for} (@pxref{Waiting}), and in | |
1281 | @code{accept-process-output} (@pxref{Accepting Output}). | |
b8d4c8d0 GM |
1282 | |
1283 | A filter function must accept two arguments: the associated process | |
1284 | and a string, which is output just received from it. The function is | |
1285 | then free to do whatever it chooses with the output. | |
1286 | ||
016a35df | 1287 | @c Note this text is duplicated in the sentinels section. |
b8d4c8d0 GM |
1288 | Quitting is normally inhibited within a filter function---otherwise, |
1289 | the effect of typing @kbd{C-g} at command level or to quit a user | |
1290 | command would be unpredictable. If you want to permit quitting inside | |
1291 | a filter function, bind @code{inhibit-quit} to @code{nil}. In most | |
1292 | cases, the right way to do this is with the macro | |
1293 | @code{with-local-quit}. @xref{Quitting}. | |
1294 | ||
1295 | If an error happens during execution of a filter function, it is | |
1296 | caught automatically, so that it doesn't stop the execution of whatever | |
1297 | program was running when the filter function was started. However, if | |
62f4b18c GM |
1298 | @code{debug-on-error} is non-@code{nil}, errors are not caught. |
1299 | This makes it possible to use the Lisp debugger to debug the | |
b8d4c8d0 GM |
1300 | filter function. @xref{Debugger}. |
1301 | ||
62f4b18c | 1302 | Many filter functions sometimes (or always) insert the output in the |
b8d4c8d0 | 1303 | process's buffer, mimicking the actions of Emacs when there is no |
62f4b18c GM |
1304 | filter. Such filter functions need to make sure that they save the |
1305 | current buffer, select the correct buffer (if different) before | |
1306 | inserting output, and then restore the original buffer. | |
1307 | They should also check whether the buffer is still alive, update the | |
1308 | process marker, and in some cases update the value of point. Here is | |
1309 | how to do these things: | |
1310 | ||
1311 | @anchor{Process Filter Example} | |
b8d4c8d0 GM |
1312 | @smallexample |
1313 | @group | |
1314 | (defun ordinary-insertion-filter (proc string) | |
78e33835 CY |
1315 | (when (buffer-live-p (process-buffer proc)) |
1316 | (with-current-buffer (process-buffer proc) | |
1317 | (let ((moving (= (point) (process-mark proc)))) | |
b8d4c8d0 GM |
1318 | @end group |
1319 | @group | |
78e33835 | 1320 | (save-excursion |
62f4b18c | 1321 | ;; @r{Insert the text, advancing the process marker.} |
78e33835 CY |
1322 | (goto-char (process-mark proc)) |
1323 | (insert string) | |
1324 | (set-marker (process-mark proc) (point))) | |
1325 | (if moving (goto-char (process-mark proc))))))) | |
b8d4c8d0 GM |
1326 | @end group |
1327 | @end smallexample | |
1328 | ||
b8d4c8d0 | 1329 | To make the filter force the process buffer to be visible whenever new |
62f4b18c | 1330 | text arrives, you could insert a line like the following just before the |
b8d4c8d0 GM |
1331 | @code{with-current-buffer} construct: |
1332 | ||
1333 | @smallexample | |
1334 | (display-buffer (process-buffer proc)) | |
1335 | @end smallexample | |
1336 | ||
1337 | To force point to the end of the new output, no matter where it was | |
1338 | previously, eliminate the variable @code{moving} and call | |
1339 | @code{goto-char} unconditionally. | |
1340 | ||
62f4b18c | 1341 | @ignore |
b8d4c8d0 GM |
1342 | In earlier Emacs versions, every filter function that did regular |
1343 | expression searching or matching had to explicitly save and restore the | |
1344 | match data. Now Emacs does this automatically for filter functions; | |
62f4b18c GM |
1345 | they never need to do it explicitly. |
1346 | @end ignore | |
1347 | Note that Emacs automatically saves and restores the match data | |
1348 | while executing filter functions. @xref{Match Data}. | |
b8d4c8d0 | 1349 | |
62f4b18c | 1350 | The output to the filter may come in chunks of any size. A program |
b8d4c8d0 GM |
1351 | that produces the same output twice in a row may send it as one batch of |
1352 | 200 characters one time, and five batches of 40 characters the next. If | |
1353 | the filter looks for certain text strings in the subprocess output, make | |
1354 | sure to handle the case where one of these strings is split across two | |
fd211f0b CY |
1355 | or more batches of output; one way to do this is to insert the |
1356 | received text into a temporary buffer, which can then be searched. | |
b8d4c8d0 GM |
1357 | |
1358 | @defun set-process-filter process filter | |
1359 | This function gives @var{process} the filter function @var{filter}. If | |
1360 | @var{filter} is @code{nil}, it gives the process no filter. | |
1361 | @end defun | |
1362 | ||
1363 | @defun process-filter process | |
1364 | This function returns the filter function of @var{process}, or @code{nil} | |
1365 | if it has none. | |
1366 | @end defun | |
1367 | ||
62f4b18c | 1368 | Here is an example of the use of a filter function: |
b8d4c8d0 GM |
1369 | |
1370 | @smallexample | |
1371 | @group | |
1372 | (defun keep-output (process output) | |
1373 | (setq kept (cons output kept))) | |
1374 | @result{} keep-output | |
1375 | @end group | |
1376 | @group | |
1377 | (setq kept nil) | |
1378 | @result{} nil | |
1379 | @end group | |
1380 | @group | |
1381 | (set-process-filter (get-process "shell") 'keep-output) | |
1382 | @result{} keep-output | |
1383 | @end group | |
1384 | @group | |
1385 | (process-send-string "shell" "ls ~/other\n") | |
1386 | @result{} nil | |
1387 | kept | |
62f4b18c | 1388 | @result{} ("lewis@@slug:$ " |
b8d4c8d0 GM |
1389 | @end group |
1390 | @group | |
1391 | "FINAL-W87-SHORT.MSS backup.otl kolstad.mss~ | |
1392 | address.txt backup.psf kolstad.psf | |
1393 | backup.bib~ david.mss resume-Dec-86.mss~ | |
1394 | backup.err david.psf resume-Dec.psf | |
1395 | backup.mss dland syllabus.mss | |
1396 | " | |
1397 | "#backups.mss# backup.mss~ kolstad.mss | |
1398 | ") | |
1399 | @end group | |
1400 | @end smallexample | |
1401 | ||
1402 | @ignore @c The code in this example doesn't show the right way to do things. | |
1403 | Here is another, more realistic example, which demonstrates how to use | |
1404 | the process mark to do insertion in the same fashion as is done when | |
1405 | there is no filter function: | |
1406 | ||
1407 | @smallexample | |
1408 | @group | |
1409 | ;; @r{Insert input in the buffer specified by @code{my-shell-buffer}} | |
1410 | ;; @r{and make sure that buffer is shown in some window.} | |
1411 | (defun my-process-filter (proc str) | |
1412 | (let ((cur (selected-window)) | |
1413 | (pop-up-windows t)) | |
1414 | (pop-to-buffer my-shell-buffer) | |
1415 | @end group | |
1416 | @group | |
1417 | (goto-char (point-max)) | |
1418 | (insert str) | |
1419 | (set-marker (process-mark proc) (point-max)) | |
1420 | (select-window cur))) | |
1421 | @end group | |
1422 | @end smallexample | |
1423 | @end ignore | |
1424 | ||
1425 | @node Decoding Output | |
1426 | @subsection Decoding Process Output | |
1427 | @cindex decode process output | |
1428 | ||
1429 | When Emacs writes process output directly into a multibyte buffer, | |
1430 | it decodes the output according to the process output coding system. | |
1431 | If the coding system is @code{raw-text} or @code{no-conversion}, Emacs | |
1432 | converts the unibyte output to multibyte using | |
1433 | @code{string-to-multibyte}, and inserts the resulting multibyte text. | |
1434 | ||
1435 | You can use @code{set-process-coding-system} to specify which coding | |
1436 | system to use (@pxref{Process Information}). Otherwise, the coding | |
1437 | system comes from @code{coding-system-for-read}, if that is | |
1438 | non-@code{nil}; or else from the defaulting mechanism (@pxref{Default | |
3355f04d EZ |
1439 | Coding Systems}). If the text output by a process contains null |
1440 | bytes, Emacs by default uses @code{no-conversion} for it; see | |
1441 | @ref{Lisp and Coding Systems, inhibit-null-byte-detection}, for how to | |
1442 | control this behavior. | |
b8d4c8d0 | 1443 | |
62f4b18c GM |
1444 | @strong{Warning:} Coding systems such as @code{undecided}, which |
1445 | determine the coding system from the data, do not work entirely | |
b8d4c8d0 GM |
1446 | reliably with asynchronous subprocess output. This is because Emacs |
1447 | has to process asynchronous subprocess output in batches, as it | |
1448 | arrives. Emacs must try to detect the proper coding system from one | |
1449 | batch at a time, and this does not always work. Therefore, if at all | |
1450 | possible, specify a coding system that determines both the character | |
1451 | code conversion and the end of line conversion---that is, one like | |
1452 | @code{latin-1-unix}, rather than @code{undecided} or @code{latin-1}. | |
1453 | ||
4972c361 SM |
1454 | @c Let's keep the index entries that were there for |
1455 | @c set-process-filter-multibyte and process-filter-multibyte-p, | |
b8d4c8d0 GM |
1456 | @cindex filter multibyte flag, of process |
1457 | @cindex process filter multibyte flag | |
1458 | When Emacs calls a process filter function, it provides the process | |
1459 | output as a multibyte string or as a unibyte string according to the | |
4972c361 SM |
1460 | process's filter coding system. Emacs |
1461 | decodes the output according to the process output coding system, | |
1462 | which usually produces a multibyte string, except for coding systems | |
62f4b18c | 1463 | such as @code{binary} and @code{raw-text}. |
b8d4c8d0 GM |
1464 | |
1465 | @node Accepting Output | |
1466 | @subsection Accepting Output from Processes | |
1467 | @cindex accept input from processes | |
1468 | ||
1469 | Output from asynchronous subprocesses normally arrives only while | |
1470 | Emacs is waiting for some sort of external event, such as elapsed time | |
1471 | or terminal input. Occasionally it is useful in a Lisp program to | |
1472 | explicitly permit output to arrive at a specific point, or even to wait | |
1473 | until output arrives from a process. | |
1474 | ||
1475 | @defun accept-process-output &optional process seconds millisec just-this-one | |
1476 | This function allows Emacs to read pending output from processes. The | |
1477 | output is inserted in the associated buffers or given to their filter | |
1478 | functions. If @var{process} is non-@code{nil} then this function does | |
1479 | not return until some output has been received from @var{process}. | |
1480 | ||
b8d4c8d0 GM |
1481 | The arguments @var{seconds} and @var{millisec} let you specify timeout |
1482 | periods. The former specifies a period measured in seconds and the | |
1483 | latter specifies one measured in milliseconds. The two time periods | |
1484 | thus specified are added together, and @code{accept-process-output} | |
1485 | returns after that much time, whether or not there has been any | |
1486 | subprocess output. | |
1487 | ||
4f5d565f GM |
1488 | The argument @var{millisec} is obsolete (and should not be used), |
1489 | because @var{seconds} can be a floating point number to specify | |
1490 | waiting a fractional number of seconds. If @var{seconds} is 0, the | |
1491 | function accepts whatever output is pending but does not wait. | |
b8d4c8d0 GM |
1492 | |
1493 | @c Emacs 22.1 feature | |
1494 | If @var{process} is a process, and the argument @var{just-this-one} is | |
1495 | non-@code{nil}, only output from that process is handled, suspending output | |
1496 | from other processes until some output has been received from that | |
1497 | process or the timeout expires. If @var{just-this-one} is an integer, | |
1498 | also inhibit running timers. This feature is generally not | |
1499 | recommended, but may be necessary for specific applications, such as | |
1500 | speech synthesis. | |
1501 | ||
1502 | The function @code{accept-process-output} returns non-@code{nil} if it | |
1503 | did get some output, or @code{nil} if the timeout expired before output | |
1504 | arrived. | |
1505 | @end defun | |
1506 | ||
1507 | @node Sentinels | |
1508 | @section Sentinels: Detecting Process Status Changes | |
1509 | @cindex process sentinel | |
1510 | @cindex sentinel (of process) | |
1511 | ||
1512 | A @dfn{process sentinel} is a function that is called whenever the | |
1513 | associated process changes status for any reason, including signals | |
1514 | (whether sent by Emacs or caused by the process's own actions) that | |
1515 | terminate, stop, or continue the process. The process sentinel is | |
1516 | also called if the process exits. The sentinel receives two | |
1517 | arguments: the process for which the event occurred, and a string | |
1518 | describing the type of event. | |
1519 | ||
1520 | The string describing the event looks like one of the following: | |
1521 | ||
016a35df | 1522 | @c FIXME? Also "killed\n" - see example below? |
b8d4c8d0 GM |
1523 | @itemize @bullet |
1524 | @item | |
1525 | @code{"finished\n"}. | |
1526 | ||
1527 | @item | |
1528 | @code{"exited abnormally with code @var{exitcode}\n"}. | |
1529 | ||
1530 | @item | |
1531 | @code{"@var{name-of-signal}\n"}. | |
1532 | ||
1533 | @item | |
1534 | @code{"@var{name-of-signal} (core dumped)\n"}. | |
1535 | @end itemize | |
1536 | ||
1537 | A sentinel runs only while Emacs is waiting (e.g., for terminal | |
1538 | input, or for time to elapse, or for process output). This avoids the | |
016a35df | 1539 | timing errors that could result from running sentinels at random places in |
b8d4c8d0 GM |
1540 | the middle of other Lisp programs. A program can wait, so that |
1541 | sentinels will run, by calling @code{sit-for} or @code{sleep-for} | |
1542 | (@pxref{Waiting}), or @code{accept-process-output} (@pxref{Accepting | |
1543 | Output}). Emacs also allows sentinels to run when the command loop is | |
1544 | reading input. @code{delete-process} calls the sentinel when it | |
1545 | terminates a running process. | |
1546 | ||
1547 | Emacs does not keep a queue of multiple reasons to call the sentinel | |
1548 | of one process; it records just the current status and the fact that | |
1549 | there has been a change. Therefore two changes in status, coming in | |
1550 | quick succession, can call the sentinel just once. However, process | |
1551 | termination will always run the sentinel exactly once. This is | |
1552 | because the process status can't change again after termination. | |
1553 | ||
1554 | Emacs explicitly checks for output from the process before running | |
1555 | the process sentinel. Once the sentinel runs due to process | |
1556 | termination, no further output can arrive from the process. | |
1557 | ||
1558 | A sentinel that writes the output into the buffer of the process | |
1559 | should check whether the buffer is still alive. If it tries to insert | |
1560 | into a dead buffer, it will get an error. If the buffer is dead, | |
1561 | @code{(buffer-name (process-buffer @var{process}))} returns @code{nil}. | |
1562 | ||
016a35df | 1563 | @c Note this text is duplicated in the filter functions section. |
b8d4c8d0 GM |
1564 | Quitting is normally inhibited within a sentinel---otherwise, the |
1565 | effect of typing @kbd{C-g} at command level or to quit a user command | |
1566 | would be unpredictable. If you want to permit quitting inside a | |
1567 | sentinel, bind @code{inhibit-quit} to @code{nil}. In most cases, the | |
1568 | right way to do this is with the macro @code{with-local-quit}. | |
1569 | @xref{Quitting}. | |
1570 | ||
1571 | If an error happens during execution of a sentinel, it is caught | |
1572 | automatically, so that it doesn't stop the execution of whatever | |
1573 | programs was running when the sentinel was started. However, if | |
016a35df GM |
1574 | @code{debug-on-error} is non-@code{nil}, errors are not caught. |
1575 | This makes it possible to use the Lisp debugger to debug the | |
b8d4c8d0 GM |
1576 | sentinel. @xref{Debugger}. |
1577 | ||
1578 | While a sentinel is running, the process sentinel is temporarily | |
1579 | set to @code{nil} so that the sentinel won't run recursively. | |
1580 | For this reason it is not possible for a sentinel to specify | |
1581 | a new sentinel. | |
1582 | ||
016a35df | 1583 | @ignore |
b8d4c8d0 GM |
1584 | In earlier Emacs versions, every sentinel that did regular expression |
1585 | searching or matching had to explicitly save and restore the match data. | |
1586 | Now Emacs does this automatically for sentinels; they never need to do | |
016a35df GM |
1587 | it explicitly. |
1588 | @end ignore | |
1589 | Note that Emacs automatically saves and restores the match data | |
1590 | while executing sentinels. @xref{Match Data}. | |
b8d4c8d0 GM |
1591 | |
1592 | @defun set-process-sentinel process sentinel | |
1593 | This function associates @var{sentinel} with @var{process}. If | |
1594 | @var{sentinel} is @code{nil}, then the process will have no sentinel. | |
1595 | The default behavior when there is no sentinel is to insert a message in | |
1596 | the process's buffer when the process status changes. | |
1597 | ||
016a35df | 1598 | Changes in process sentinels take effect immediately---if the sentinel |
b8d4c8d0 GM |
1599 | is slated to be run but has not been called yet, and you specify a new |
1600 | sentinel, the eventual call to the sentinel will use the new one. | |
1601 | ||
1602 | @smallexample | |
1603 | @group | |
1604 | (defun msg-me (process event) | |
1605 | (princ | |
1606 | (format "Process: %s had the event `%s'" process event))) | |
1607 | (set-process-sentinel (get-process "shell") 'msg-me) | |
1608 | @result{} msg-me | |
1609 | @end group | |
1610 | @group | |
1611 | (kill-process (get-process "shell")) | |
1612 | @print{} Process: #<process shell> had the event `killed' | |
1613 | @result{} #<process shell> | |
1614 | @end group | |
1615 | @end smallexample | |
1616 | @end defun | |
1617 | ||
1618 | @defun process-sentinel process | |
1619 | This function returns the sentinel of @var{process}, or @code{nil} if it | |
1620 | has none. | |
1621 | @end defun | |
1622 | ||
1623 | @defun waiting-for-user-input-p | |
1624 | While a sentinel or filter function is running, this function returns | |
1625 | non-@code{nil} if Emacs was waiting for keyboard input from the user at | |
016a35df | 1626 | the time the sentinel or filter function was called, or @code{nil} if it |
b8d4c8d0 GM |
1627 | was not. |
1628 | @end defun | |
1629 | ||
1630 | @node Query Before Exit | |
1631 | @section Querying Before Exit | |
1632 | ||
1633 | When Emacs exits, it terminates all its subprocesses by sending them | |
1634 | the @code{SIGHUP} signal. Because subprocesses may be doing | |
1635 | valuable work, Emacs normally asks the user to confirm that it is ok | |
016a35df | 1636 | to terminate them. Each process has a query flag, which, if |
b8d4c8d0 GM |
1637 | non-@code{nil}, says that Emacs should ask for confirmation before |
1638 | exiting and thus killing that process. The default for the query flag | |
1639 | is @code{t}, meaning @emph{do} query. | |
1640 | ||
1641 | @defun process-query-on-exit-flag process | |
1642 | This returns the query flag of @var{process}. | |
1643 | @end defun | |
1644 | ||
1645 | @defun set-process-query-on-exit-flag process flag | |
1646 | This function sets the query flag of @var{process} to @var{flag}. It | |
1647 | returns @var{flag}. | |
1648 | ||
9fe9631c CY |
1649 | Here is an example of using @code{set-process-query-on-exit-flag} on a |
1650 | shell process to avoid querying: | |
1651 | ||
b8d4c8d0 GM |
1652 | @smallexample |
1653 | @group | |
b8d4c8d0 | 1654 | (set-process-query-on-exit-flag (get-process "shell") nil) |
016a35df | 1655 | @result{} nil |
b8d4c8d0 GM |
1656 | @end group |
1657 | @end smallexample | |
1658 | @end defun | |
1659 | ||
23dd4ecd EZ |
1660 | @node System Processes |
1661 | @section Accessing Other Processes | |
1662 | @cindex system processes | |
1663 | ||
1664 | In addition to accessing and manipulating processes that are | |
1665 | subprocesses of the current Emacs session, Emacs Lisp programs can | |
1666 | also access other processes running on the same machine. We call | |
016a35df | 1667 | these @dfn{system processes}, to distinguish them from Emacs |
23dd4ecd EZ |
1668 | subprocesses. |
1669 | ||
1670 | Emacs provides several primitives for accessing system processes. | |
1671 | Not all platforms support these primitives; on those which don't, | |
1672 | these primitives return @code{nil}. | |
1673 | ||
1674 | @defun list-system-processes | |
1675 | This function returns a list of all the processes running on the | |
1676 | system. Each process is identified by its @acronym{PID}, a numerical | |
1677 | process ID that is assigned by the OS and distinguishes the process | |
1678 | from all the other processes running on the same machine at the same | |
1679 | time. | |
1680 | @end defun | |
1681 | ||
a20878b6 | 1682 | @defun process-attributes pid |
23dd4ecd EZ |
1683 | This function returns an alist of attributes for the process specified |
1684 | by its process ID @var{pid}. Each association in the alist is of the | |
1685 | form @code{(@var{key} . @var{value})}, where @var{key} designates the | |
1686 | attribute and @var{value} is the value of that attribute. The various | |
016a35df | 1687 | attribute @var{key}s that this function can return are listed below. |
23dd4ecd EZ |
1688 | Not all platforms support all of these attributes; if an attribute is |
1689 | not supported, its association will not appear in the returned alist. | |
1690 | Values that are numbers can be either integer or floating-point, | |
1691 | depending on the magnitude of the value. | |
1692 | ||
1693 | @table @code | |
1694 | @item euid | |
1695 | The effective user ID of the user who invoked the process. The | |
1696 | corresponding @var{value} is a number. If the process was invoked by | |
1697 | the same user who runs the current Emacs session, the value is | |
1698 | identical to what @code{user-uid} returns (@pxref{User | |
1699 | Identification}). | |
1700 | ||
1701 | @item user | |
1702 | User name corresponding to the process's effective user ID, a string. | |
1703 | ||
1704 | @item egid | |
1705 | The group ID of the effective user ID, a number. | |
1706 | ||
1707 | @item group | |
1708 | Group name corresponding to the effective user's group ID, a string. | |
1709 | ||
1710 | @item comm | |
1711 | The name of the command that runs in the process. This is a string | |
1712 | that usually specifies the name of the executable file of the process, | |
1713 | without the leading directories. However, some special system | |
1714 | processes can report strings that do not correspond to an executable | |
1715 | file of a program. | |
1716 | ||
1717 | @item state | |
1718 | The state code of the process. This is a short string that encodes | |
1719 | the scheduling state of the process. Here's a list of the most | |
1720 | frequently seen codes: | |
1721 | ||
1722 | @table @code | |
1dca458f | 1723 | @item "D" |
23dd4ecd | 1724 | uninterruptible sleep (usually I/O) |
1dca458f | 1725 | @item "R" |
23dd4ecd | 1726 | running |
1dca458f | 1727 | @item "S" |
23dd4ecd | 1728 | interruptible sleep (waiting for some event) |
1dca458f | 1729 | @item "T" |
23dd4ecd | 1730 | stopped, e.g., by a job control signal |
1dca458f EZ |
1731 | @item "Z" |
1732 | ``zombie'': a process that terminated, but was not reaped by its parent | |
23dd4ecd EZ |
1733 | @end table |
1734 | ||
1735 | @noindent | |
1736 | For the full list of the possible states, see the manual page of the | |
1737 | @command{ps} command. | |
1738 | ||
1739 | @item ppid | |
1740 | The process ID of the parent process, a number. | |
1741 | ||
1742 | @item pgrp | |
1743 | The process group ID of the process, a number. | |
1744 | ||
1745 | @item sess | |
1746 | The session ID of the process. This is a number that is the process | |
1747 | ID of the process's @dfn{session leader}. | |
1748 | ||
1749 | @item ttname | |
1750 | A string that is the name of the process's controlling terminal. On | |
1751 | Unix and GNU systems, this is normally the file name of the | |
1752 | corresponding terminal device, such as @file{/dev/pts65}. | |
1753 | ||
1754 | @item tpgid | |
1755 | The numerical process group ID of the foreground process group that | |
1756 | uses the process's terminal. | |
1757 | ||
1758 | @item minflt | |
1759 | The number of minor page faults caused by the process since its | |
1760 | beginning. (Minor page faults are those that don't involve reading | |
1761 | from disk.) | |
1762 | ||
1763 | @item majflt | |
1764 | The number of major page faults caused by the process since its | |
1765 | beginning. (Major page faults require a disk to be read, and are thus | |
1766 | more expensive than minor page faults.) | |
1767 | ||
1768 | @item cminflt | |
1769 | @itemx cmajflt | |
1770 | Like @code{minflt} and @code{majflt}, but include the number of page | |
1771 | faults for all the child processes of the given process. | |
1772 | ||
1773 | @item utime | |
1774 | Time spent by the process in the user context, for running the | |
1775 | application's code. The corresponding @var{value} is in the | |
d35af63c | 1776 | @w{@code{(@var{high} @var{low} @var{microsec} @var{picosec})}} format, the same |
23dd4ecd EZ |
1777 | format used by functions @code{current-time} (@pxref{Time of Day, |
1778 | current-time}) and @code{file-attributes} (@pxref{File Attributes}). | |
1779 | ||
1780 | @item stime | |
1781 | Time spent by the process in the system (kernel) context, for | |
1782 | processing system calls. The corresponding @var{value} is in the same | |
1783 | format as for @code{utime}. | |
1784 | ||
af34ad36 EZ |
1785 | @item time |
1786 | The sum of @code{utime} and @code{stime}. The corresponding | |
1787 | @var{value} is in the same format as for @code{utime}. | |
1788 | ||
23dd4ecd EZ |
1789 | @item cutime |
1790 | @itemx cstime | |
af34ad36 EZ |
1791 | @itemx ctime |
1792 | Like @code{utime}, @code{stime}, and @code{time}, but include the | |
1793 | times of all the child processes of the given process. | |
23dd4ecd EZ |
1794 | |
1795 | @item pri | |
1796 | The numerical priority of the process. | |
1797 | ||
1798 | @item nice | |
1dca458f EZ |
1799 | The @dfn{nice value} of the process, a number. (Processes with smaller |
1800 | nice values get scheduled more favorably.) | |
23dd4ecd EZ |
1801 | |
1802 | @item thcount | |
1803 | The number of threads in the process. | |
1804 | ||
1805 | @item start | |
049bcbcb | 1806 | The time when the process was started, in the same |
d35af63c | 1807 | @w{@code{(@var{high} @var{low} @var{microsec} @var{picosec})}} format used by |
84f4a531 | 1808 | @code{current-time} and by @code{file-attributes}. |
23dd4ecd EZ |
1809 | |
1810 | @item etime | |
1811 | The time elapsed since the process started, in the @w{@code{(@var{high} | |
d35af63c | 1812 | @var{low} @var{microsec} @var{picosec})}} format. |
23dd4ecd EZ |
1813 | |
1814 | @item vsize | |
1815 | The virtual memory size of the process, measured in kilobytes. | |
1816 | ||
1817 | @item rss | |
1818 | The size of the process's @dfn{resident set}, the number of kilobytes | |
1819 | occupied by the process in the machine's physical memory. | |
1820 | ||
1821 | @item pcpu | |
1822 | The percentage of the CPU time used by the process since it started. | |
1823 | The corresponding @var{value} is a floating-point number between 0 and | |
1824 | 100. | |
1825 | ||
1826 | @item pmem | |
1827 | The percentage of the total physical memory installed on the machine | |
1828 | used by the process's resident set. The value is a floating-point | |
1829 | number between 0 and 100. | |
1830 | ||
1831 | @item args | |
1832 | The command-line with which the process was invoked. This is a string | |
1833 | in which individual command-line arguments are separated by blanks; | |
1834 | whitespace characters that are embedded in the arguments are quoted as | |
1835 | appropriate for the system's shell: escaped by backslash characters on | |
1836 | GNU and Unix, and enclosed in double quote characters on Windows. | |
1837 | Thus, this command-line string can be directly used in primitives such | |
1838 | as @code{shell-command}. | |
1839 | @end table | |
1840 | ||
1841 | @end defun | |
1842 | ||
1843 | ||
b8d4c8d0 GM |
1844 | @node Transaction Queues |
1845 | @section Transaction Queues | |
1846 | @cindex transaction queue | |
1847 | ||
016a35df GM |
1848 | @c That's not very informative. What is a transaction, and when might |
1849 | @c I want to use one? | |
b8d4c8d0 GM |
1850 | You can use a @dfn{transaction queue} to communicate with a subprocess |
1851 | using transactions. First use @code{tq-create} to create a transaction | |
1852 | queue communicating with a specified process. Then you can call | |
1853 | @code{tq-enqueue} to send a transaction. | |
1854 | ||
1855 | @defun tq-create process | |
1856 | This function creates and returns a transaction queue communicating with | |
1857 | @var{process}. The argument @var{process} should be a subprocess | |
1858 | capable of sending and receiving streams of bytes. It may be a child | |
1859 | process, or it may be a TCP connection to a server, possibly on another | |
1860 | machine. | |
1861 | @end defun | |
1862 | ||
1863 | @defun tq-enqueue queue question regexp closure fn &optional delay-question | |
1864 | This function sends a transaction to queue @var{queue}. Specifying the | |
1865 | queue has the effect of specifying the subprocess to talk to. | |
1866 | ||
1867 | The argument @var{question} is the outgoing message that starts the | |
1868 | transaction. The argument @var{fn} is the function to call when the | |
1869 | corresponding answer comes back; it is called with two arguments: | |
1870 | @var{closure}, and the answer received. | |
1871 | ||
1872 | The argument @var{regexp} is a regular expression that should match | |
1873 | text at the end of the entire answer, but nothing before; that's how | |
1874 | @code{tq-enqueue} determines where the answer ends. | |
1875 | ||
4185820c CY |
1876 | If the argument @var{delay-question} is non-@code{nil}, delay sending |
1877 | this question until the process has finished replying to any previous | |
b8d4c8d0 | 1878 | questions. This produces more reliable results with some processes. |
016a35df | 1879 | @ignore |
b8d4c8d0 | 1880 | |
016a35df | 1881 | @c Let's not mention it then. |
b8d4c8d0 | 1882 | The return value of @code{tq-enqueue} itself is not meaningful. |
016a35df | 1883 | @end ignore |
b8d4c8d0 GM |
1884 | @end defun |
1885 | ||
1886 | @defun tq-close queue | |
1887 | Shut down transaction queue @var{queue}, waiting for all pending transactions | |
1888 | to complete, and then terminate the connection or child process. | |
1889 | @end defun | |
1890 | ||
1891 | Transaction queues are implemented by means of a filter function. | |
1892 | @xref{Filter Functions}. | |
1893 | ||
1894 | @node Network | |
1895 | @section Network Connections | |
1896 | @cindex network connection | |
1897 | @cindex TCP | |
1898 | @cindex UDP | |
1899 | ||
1900 | Emacs Lisp programs can open stream (TCP) and datagram (UDP) network | |
016a35df GM |
1901 | connections (@pxref{Datagrams}) to other processes on the same machine |
1902 | or other machines. | |
b8d4c8d0 GM |
1903 | A network connection is handled by Lisp much like a subprocess, and is |
1904 | represented by a process object. However, the process you are | |
016a35df | 1905 | communicating with is not a child of the Emacs process, has no |
b8d4c8d0 GM |
1906 | process @acronym{ID}, and you can't kill it or send it signals. All you |
1907 | can do is send and receive data. @code{delete-process} closes the | |
1908 | connection, but does not kill the program at the other end; that | |
1909 | program must decide what to do about closure of the connection. | |
1910 | ||
1911 | Lisp programs can listen for connections by creating network | |
1912 | servers. A network server is also represented by a kind of process | |
1913 | object, but unlike a network connection, the network server never | |
1914 | transfers data itself. When it receives a connection request, it | |
1915 | creates a new network connection to represent the connection just | |
1916 | made. (The network connection inherits certain information, including | |
1917 | the process plist, from the server.) The network server then goes | |
1918 | back to listening for more connection requests. | |
1919 | ||
1920 | Network connections and servers are created by calling | |
1921 | @code{make-network-process} with an argument list consisting of | |
1922 | keyword/argument pairs, for example @code{:server t} to create a | |
1923 | server process, or @code{:type 'datagram} to create a datagram | |
1924 | connection. @xref{Low-Level Network}, for details. You can also use | |
1925 | the @code{open-network-stream} function described below. | |
1926 | ||
c73e02fa GM |
1927 | To distinguish the different types of processes, the |
1928 | @code{process-type} function returns the symbol @code{network} for a | |
1929 | network connection or server, @code{serial} for a serial port | |
1930 | connection, or @code{real} for a real subprocess. | |
1931 | ||
1932 | The @code{process-status} function returns @code{open}, | |
016a35df | 1933 | @code{closed}, @code{connect}, or @code{failed} for network |
c73e02fa | 1934 | connections. For a network server, the status is always |
b8d4c8d0 GM |
1935 | @code{listen}. None of those values is possible for a real |
1936 | subprocess. @xref{Process Information}. | |
1937 | ||
1938 | You can stop and resume operation of a network process by calling | |
1939 | @code{stop-process} and @code{continue-process}. For a server | |
1940 | process, being stopped means not accepting new connections. (Up to 5 | |
1941 | connection requests will be queued for when you resume the server; you | |
1942 | can increase this limit, unless it is imposed by the operating | |
016a35df GM |
1943 | system---see the @code{:server} keyword of @code{make-network-process}, |
1944 | @ref{Network Processes}.) For a network stream connection, being | |
1945 | stopped means not processing input (any arriving input waits until you | |
1946 | resume the connection). For a datagram connection, some number of | |
1947 | packets may be queued but input may be lost. You can use the function | |
b8d4c8d0 GM |
1948 | @code{process-command} to determine whether a network connection or |
1949 | server is stopped; a non-@code{nil} value means yes. | |
1950 | ||
fcacfa8d | 1951 | @cindex network connection, encrypted |
d7dbb11a | 1952 | @cindex encrypted network connections |
016a35df GM |
1953 | @cindex @acronym{TLS} network connections |
1954 | @cindex @acronym{STARTTLS} network connections | |
1955 | Emacs can create encrypted network connections, using either built-in | |
1956 | or external support. The built-in support uses the GnuTLS | |
1957 | (``Transport Layer Security'') library; see | |
1958 | @uref{http://www.gnu.org/software/gnutls/, the GnuTLS project page}. | |
1959 | If your Emacs was compiled with GnuTLS support, the function | |
1960 | @code{gnutls-available-p} is defined and returns non-@code{nil}. For | |
1961 | more details, @pxref{Top,, Overview, emacs-gnutls, The Emacs-GnuTLS manual}. | |
1962 | The external support uses the @file{starttls.el} library, which | |
1963 | requires a helper utility such as @command{gnutls-cli} to be installed | |
1964 | on the system. The @code{open-network-stream} function can | |
1965 | transparently handle the details of creating encrypted connections for | |
1966 | you, using whatever support is available. | |
1967 | ||
1968 | @defun open-network-stream name buffer host service &rest parameters | |
d7dbb11a GM |
1969 | This function opens a TCP connection, with optional encryption, and |
1970 | returns a process object that represents the connection. | |
b8d4c8d0 GM |
1971 | |
1972 | The @var{name} argument specifies the name for the process object. It | |
1973 | is modified as necessary to make it unique. | |
1974 | ||
016a35df | 1975 | The @var{buffer} argument is the buffer to associate with the |
b8d4c8d0 GM |
1976 | connection. Output from the connection is inserted in the buffer, |
1977 | unless you specify a filter function to handle the output. If | |
016a35df | 1978 | @var{buffer} is @code{nil}, it means that the connection is not |
b8d4c8d0 GM |
1979 | associated with any buffer. |
1980 | ||
1981 | The arguments @var{host} and @var{service} specify where to connect to; | |
1982 | @var{host} is the host name (a string), and @var{service} is the name of | |
1983 | a defined network service (a string) or a port number (an integer). | |
d7dbb11a | 1984 | |
d7dbb11a GM |
1985 | The remaining arguments @var{parameters} are keyword/argument pairs |
1986 | that are mainly relevant to encrypted connections: | |
1987 | ||
1988 | @table @code | |
1989 | ||
1990 | @item :nowait @var{boolean} | |
1991 | If non-@code{nil}, try to make an asynchronous connection. | |
1992 | ||
1993 | @item :type @var{type} | |
1994 | The type of connection. Options are: | |
1995 | ||
1996 | @table @code | |
1997 | @item plain | |
1998 | An ordinary, unencrypted connection. | |
1999 | @item tls | |
2000 | @itemx ssl | |
016a35df | 2001 | A @acronym{TLS} (``Transport Layer Security'') connection. |
d7dbb11a GM |
2002 | @item nil |
2003 | @itemx network | |
2004 | Start with a plain connection, and if parameters @samp{:success} | |
2005 | and @samp{:capability-command} are supplied, try to upgrade to an encrypted | |
016a35df GM |
2006 | connection via @acronym{STARTTLS}. If that fails, retain the |
2007 | unencrypted connection. | |
d7dbb11a | 2008 | @item starttls |
016a35df | 2009 | As for @code{nil}, but if @acronym{STARTTLS} fails drop the connection. |
d7dbb11a GM |
2010 | @item shell |
2011 | A shell connection. | |
2012 | @end table | |
2013 | ||
2014 | @item :always-query-capabilities @var{boolean} | |
2015 | If non-@code{nil}, always ask for the server's capabilities, even when | |
2016 | doing a @samp{plain} connection. | |
2017 | ||
2018 | @item :capability-command @var{capability-command} | |
2019 | Command string to query the host capabilities. | |
2020 | ||
2021 | @item :end-of-command @var{regexp} | |
2022 | @itemx :end-of-capability @var{regexp} | |
2023 | Regular expression matching the end of a command, or the end of the | |
2024 | command @var{capability-command}. The latter defaults to the former. | |
2025 | ||
2026 | @item :starttls-function @var{function} | |
2027 | Function of one argument (the response to @var{capability-command}), | |
016a35df | 2028 | which returns either @code{nil}, or the command to activate @acronym{STARTTLS} |
d7dbb11a GM |
2029 | if supported. |
2030 | ||
2031 | @item :success @var{regexp} | |
016a35df | 2032 | Regular expression matching a successful @acronym{STARTTLS} negotiation. |
d7dbb11a GM |
2033 | |
2034 | @item :use-starttls-if-possible @var{boolean} | |
016a35df GM |
2035 | If non-@code{nil}, do opportunistic @acronym{STARTTLS} upgrades even if Emacs |
2036 | doesn't have built-in @acronym{TLS} support. | |
d7dbb11a GM |
2037 | |
2038 | @item :client-certificate @var{list-or-t} | |
2039 | Either a list of the form @code{(@var{key-file} @var{cert-file})}, | |
2040 | naming the certificate key file and certificate file itself, or | |
2041 | @code{t}, meaning to query @code{auth-source} for this information | |
016a35df GM |
2042 | (@pxref{Top,,Overview, auth, The Auth-Source Manual}). |
2043 | Only used for @acronym{TLS} or @acronym{STARTTLS}. | |
d7dbb11a GM |
2044 | |
2045 | @item :return-list @var{cons-or-nil} | |
2046 | The return value of this function. If omitted or @code{nil}, return a | |
2047 | process object. Otherwise, a cons of the form @code{(@var{process-object} | |
2048 | . @var{plist})}, where @var{plist} has keywords: | |
2049 | ||
2050 | @table @code | |
2051 | @item :greeting @var{string-or-nil} | |
2052 | If non-@code{nil}, the greeting string returned by the host. | |
2053 | @item :capabilities @var{string-or-nil} | |
2054 | If non-@code{nil}, the host's capability string. | |
2055 | @item :type @var{symbol} | |
2056 | The connection type: @samp{plain} or @samp{tls}. | |
2057 | @end table | |
2058 | ||
2059 | @end table | |
2060 | ||
b8d4c8d0 GM |
2061 | @end defun |
2062 | ||
b8d4c8d0 GM |
2063 | @node Network Servers |
2064 | @section Network Servers | |
2065 | @cindex network servers | |
2066 | ||
016a35df GM |
2067 | You create a server by calling @code{make-network-process} |
2068 | (@pxref{Network Processes}) with @code{:server t}. The server will | |
2069 | listen for connection requests from clients. When it accepts a client | |
2070 | connection request, that creates a new network connection, itself a | |
2071 | process object, with the following parameters: | |
b8d4c8d0 GM |
2072 | |
2073 | @itemize @bullet | |
2074 | @item | |
2075 | The connection's process name is constructed by concatenating the | |
9364727b | 2076 | server process's @var{name} with a client identification string. The |
016a35df | 2077 | @c FIXME? What about IPv6? Say briefly what the difference is? |
b8d4c8d0 | 2078 | client identification string for an IPv4 connection looks like |
016a35df GM |
2079 | @samp{<@var{a}.@var{b}.@var{c}.@var{d}:@var{p}>}, which represents an |
2080 | address and port number. Otherwise, it is a | |
b8d4c8d0 GM |
2081 | unique number in brackets, as in @samp{<@var{nnn}>}. The number |
2082 | is unique for each connection in the Emacs session. | |
2083 | ||
2084 | @item | |
2085 | If the server's filter is non-@code{nil}, the connection process does | |
2086 | not get a separate process buffer; otherwise, Emacs creates a new | |
2087 | buffer for the purpose. The buffer name is the server's buffer name | |
2088 | or process name, concatenated with the client identification string. | |
2089 | ||
cec2eab8 JB |
2090 | The server's process buffer value is never used directly, but the log |
2091 | function can retrieve it and use it to log connections by inserting | |
2092 | text there. | |
b8d4c8d0 GM |
2093 | |
2094 | @item | |
2095 | The communication type and the process filter and sentinel are | |
2096 | inherited from those of the server. The server never directly | |
2097 | uses its filter and sentinel; their sole purpose is to initialize | |
2098 | connections made to the server. | |
2099 | ||
2100 | @item | |
016a35df | 2101 | The connection's process contact information is set according to the client's |
b8d4c8d0 GM |
2102 | addressing information (typically an IP address and a port number). |
2103 | This information is associated with the @code{process-contact} | |
2104 | keywords @code{:host}, @code{:service}, @code{:remote}. | |
2105 | ||
2106 | @item | |
2107 | The connection's local address is set up according to the port | |
2108 | number used for the connection. | |
2109 | ||
2110 | @item | |
9364727b | 2111 | The client process's plist is initialized from the server's plist. |
b8d4c8d0 GM |
2112 | @end itemize |
2113 | ||
2114 | @node Datagrams | |
2115 | @section Datagrams | |
2116 | @cindex datagrams | |
2117 | ||
016a35df | 2118 | A @dfn{datagram} connection communicates with individual packets rather |
b8d4c8d0 GM |
2119 | than streams of data. Each call to @code{process-send} sends one |
2120 | datagram packet (@pxref{Input to Processes}), and each datagram | |
2121 | received results in one call to the filter function. | |
2122 | ||
2123 | The datagram connection doesn't have to talk with the same remote | |
2124 | peer all the time. It has a @dfn{remote peer address} which specifies | |
2125 | where to send datagrams to. Each time an incoming datagram is passed | |
2126 | to the filter function, the peer address is set to the address that | |
2127 | datagram came from; that way, if the filter function sends a datagram, | |
2128 | it will go back to that place. You can specify the remote peer | |
2129 | address when you create the datagram connection using the | |
2130 | @code{:remote} keyword. You can change it later on by calling | |
2131 | @code{set-process-datagram-address}. | |
2132 | ||
2133 | @defun process-datagram-address process | |
2134 | If @var{process} is a datagram connection or server, this function | |
2135 | returns its remote peer address. | |
2136 | @end defun | |
2137 | ||
2138 | @defun set-process-datagram-address process address | |
2139 | If @var{process} is a datagram connection or server, this function | |
2140 | sets its remote peer address to @var{address}. | |
2141 | @end defun | |
2142 | ||
2143 | @node Low-Level Network | |
2144 | @section Low-Level Network Access | |
2145 | ||
2146 | You can also create network connections by operating at a lower | |
2147 | level than that of @code{open-network-stream}, using | |
2148 | @code{make-network-process}. | |
2149 | ||
2150 | @menu | |
2151 | * Proc: Network Processes. Using @code{make-network-process}. | |
2152 | * Options: Network Options. Further control over network connections. | |
2153 | * Features: Network Feature Testing. | |
2154 | Determining which network features work on | |
2155 | the machine you are using. | |
2156 | @end menu | |
2157 | ||
2158 | @node Network Processes | |
2159 | @subsection @code{make-network-process} | |
2160 | ||
2161 | The basic function for creating network connections and network | |
2162 | servers is @code{make-network-process}. It can do either of those | |
2163 | jobs, depending on the arguments you give it. | |
2164 | ||
2165 | @defun make-network-process &rest args | |
2166 | This function creates a network connection or server and returns the | |
2167 | process object that represents it. The arguments @var{args} are a | |
2168 | list of keyword/argument pairs. Omitting a keyword is always | |
2169 | equivalent to specifying it with value @code{nil}, except for | |
2170 | @code{:coding}, @code{:filter-multibyte}, and @code{:reuseaddr}. Here | |
016a35df GM |
2171 | are the meaningful keywords (those corresponding to network options |
2172 | are listed in the following section): | |
b8d4c8d0 GM |
2173 | |
2174 | @table @asis | |
2175 | @item :name @var{name} | |
2176 | Use the string @var{name} as the process name. It is modified if | |
2177 | necessary to make it unique. | |
2178 | ||
2179 | @item :type @var{type} | |
2180 | Specify the communication type. A value of @code{nil} specifies a | |
2181 | stream connection (the default); @code{datagram} specifies a datagram | |
f7704e26 CY |
2182 | connection; @code{seqpacket} specifies a ``sequenced packet stream'' |
2183 | connection. Both connections and servers can be of these types. | |
b8d4c8d0 GM |
2184 | |
2185 | @item :server @var{server-flag} | |
2186 | If @var{server-flag} is non-@code{nil}, create a server. Otherwise, | |
2187 | create a connection. For a stream type server, @var{server-flag} may | |
016a35df | 2188 | be an integer, which then specifies the length of the queue of pending |
b8d4c8d0 GM |
2189 | connections to the server. The default queue length is 5. |
2190 | ||
2191 | @item :host @var{host} | |
2192 | Specify the host to connect to. @var{host} should be a host name or | |
2193 | Internet address, as a string, or the symbol @code{local} to specify | |
2194 | the local host. If you specify @var{host} for a server, it must | |
2195 | specify a valid address for the local host, and only clients | |
2196 | connecting to that address will be accepted. | |
2197 | ||
2198 | @item :service @var{service} | |
016a35df | 2199 | @var{service} specifies a port number to connect to; or, for a server, |
b8d4c8d0 GM |
2200 | the port number to listen on. It should be a service name that |
2201 | translates to a port number, or an integer specifying the port number | |
2202 | directly. For a server, it can also be @code{t}, which means to let | |
2203 | the system select an unused port number. | |
2204 | ||
2205 | @item :family @var{family} | |
2206 | @var{family} specifies the address (and protocol) family for | |
2207 | communication. @code{nil} means determine the proper address family | |
2208 | automatically for the given @var{host} and @var{service}. | |
2209 | @code{local} specifies a Unix socket, in which case @var{host} is | |
016a35df | 2210 | ignored. @code{ipv4} and @code{ipv6} specify to use IPv4 and IPv6, |
b8d4c8d0 GM |
2211 | respectively. |
2212 | ||
2213 | @item :local @var{local-address} | |
2214 | For a server process, @var{local-address} is the address to listen on. | |
016a35df GM |
2215 | It overrides @var{family}, @var{host} and @var{service}, so you |
2216 | might as well not specify them. | |
b8d4c8d0 GM |
2217 | |
2218 | @item :remote @var{remote-address} | |
2219 | For a connection, @var{remote-address} is the address to connect to. | |
016a35df GM |
2220 | It overrides @var{family}, @var{host} and @var{service}, so you |
2221 | might as well not specify them. | |
b8d4c8d0 GM |
2222 | |
2223 | For a datagram server, @var{remote-address} specifies the initial | |
2224 | setting of the remote datagram address. | |
2225 | ||
2226 | The format of @var{local-address} or @var{remote-address} depends on | |
2227 | the address family: | |
2228 | ||
2229 | @itemize - | |
2230 | @item | |
2231 | An IPv4 address is represented as a five-element vector of four 8-bit | |
2232 | integers and one 16-bit integer | |
2233 | @code{[@var{a} @var{b} @var{c} @var{d} @var{p}]} corresponding to | |
2234 | numeric IPv4 address @var{a}.@var{b}.@var{c}.@var{d} and port number | |
2235 | @var{p}. | |
2236 | ||
2237 | @item | |
2238 | An IPv6 address is represented as a nine-element vector of 16-bit | |
2239 | integers @code{[@var{a} @var{b} @var{c} @var{d} @var{e} @var{f} | |
2240 | @var{g} @var{h} @var{p}]} corresponding to numeric IPv6 address | |
2241 | @var{a}:@var{b}:@var{c}:@var{d}:@var{e}:@var{f}:@var{g}:@var{h} and | |
2242 | port number @var{p}. | |
2243 | ||
2244 | @item | |
016a35df | 2245 | A local address is represented as a string, which specifies the address |
b8d4c8d0 GM |
2246 | in the local address space. |
2247 | ||
2248 | @item | |
2249 | An ``unsupported family'' address is represented by a cons | |
2250 | @code{(@var{f} . @var{av})}, where @var{f} is the family number and | |
2251 | @var{av} is a vector specifying the socket address using one element | |
2252 | per address data byte. Do not rely on this format in portable code, | |
2253 | as it may depend on implementation defined constants, data sizes, and | |
2254 | data structure alignment. | |
2255 | @end itemize | |
2256 | ||
2257 | @item :nowait @var{bool} | |
2258 | If @var{bool} is non-@code{nil} for a stream connection, return | |
2259 | without waiting for the connection to complete. When the connection | |
2260 | succeeds or fails, Emacs will call the sentinel function, with a | |
2261 | second argument matching @code{"open"} (if successful) or | |
2262 | @code{"failed"}. The default is to block, so that | |
2263 | @code{make-network-process} does not return until the connection | |
2264 | has succeeded or failed. | |
2265 | ||
2266 | @item :stop @var{stopped} | |
016a35df GM |
2267 | If @var{stopped} is non-@code{nil}, start the network connection or |
2268 | server in the ``stopped'' state. | |
b8d4c8d0 GM |
2269 | |
2270 | @item :buffer @var{buffer} | |
2271 | Use @var{buffer} as the process buffer. | |
2272 | ||
2273 | @item :coding @var{coding} | |
2274 | Use @var{coding} as the coding system for this process. To specify | |
2275 | different coding systems for decoding data from the connection and for | |
2276 | encoding data sent to it, specify @code{(@var{decoding} . | |
2277 | @var{encoding})} for @var{coding}. | |
2278 | ||
2279 | If you don't specify this keyword at all, the default | |
2280 | is to determine the coding systems from the data. | |
2281 | ||
2282 | @item :noquery @var{query-flag} | |
2283 | Initialize the process query flag to @var{query-flag}. | |
2284 | @xref{Query Before Exit}. | |
2285 | ||
2286 | @item :filter @var{filter} | |
2287 | Initialize the process filter to @var{filter}. | |
2288 | ||
016a35df GM |
2289 | @item :filter-multibyte @var{multibyte} |
2290 | If @var{multibyte} is non-@code{nil}, strings given to the process | |
2291 | filter are multibyte, otherwise they are unibyte. The default is the | |
2292 | default value of @code{enable-multibyte-characters}. | |
2293 | ||
b8d4c8d0 GM |
2294 | @item :sentinel @var{sentinel} |
2295 | Initialize the process sentinel to @var{sentinel}. | |
2296 | ||
2297 | @item :log @var{log} | |
2298 | Initialize the log function of a server process to @var{log}. The log | |
2299 | function is called each time the server accepts a network connection | |
2300 | from a client. The arguments passed to the log function are | |
016a35df | 2301 | @var{server}, @var{connection}, and @var{message}; where @var{server} |
b8d4c8d0 GM |
2302 | is the server process, @var{connection} is the new process for the |
2303 | connection, and @var{message} is a string describing what has | |
2304 | happened. | |
2305 | ||
2306 | @item :plist @var{plist} | |
2307 | Initialize the process plist to @var{plist}. | |
2308 | @end table | |
2309 | ||
2310 | The original argument list, modified with the actual connection | |
2311 | information, is available via the @code{process-contact} function. | |
2312 | @end defun | |
2313 | ||
2314 | @node Network Options | |
2315 | @subsection Network Options | |
2316 | ||
2317 | The following network options can be specified when you create a | |
2318 | network process. Except for @code{:reuseaddr}, you can also set or | |
2319 | modify these options later, using @code{set-network-process-option}. | |
2320 | ||
2321 | For a server process, the options specified with | |
2322 | @code{make-network-process} are not inherited by the client | |
2323 | connections, so you will need to set the necessary options for each | |
2324 | child connection as it is created. | |
2325 | ||
2326 | @table @asis | |
2327 | @item :bindtodevice @var{device-name} | |
2328 | If @var{device-name} is a non-empty string identifying a network | |
2329 | interface name (see @code{network-interface-list}), only handle | |
2330 | packets received on that interface. If @var{device-name} is @code{nil} | |
2331 | (the default), handle packets received on any interface. | |
2332 | ||
2333 | Using this option may require special privileges on some systems. | |
2334 | ||
2335 | @item :broadcast @var{broadcast-flag} | |
2336 | If @var{broadcast-flag} is non-@code{nil} for a datagram process, the | |
2337 | process will receive datagram packet sent to a broadcast address, and | |
016a35df | 2338 | be able to send packets to a broadcast address. This is ignored for a stream |
b8d4c8d0 GM |
2339 | connection. |
2340 | ||
2341 | @item :dontroute @var{dontroute-flag} | |
2342 | If @var{dontroute-flag} is non-@code{nil}, the process can only send | |
2343 | to hosts on the same network as the local host. | |
2344 | ||
2345 | @item :keepalive @var{keepalive-flag} | |
2346 | If @var{keepalive-flag} is non-@code{nil} for a stream connection, | |
2347 | enable exchange of low-level keep-alive messages. | |
2348 | ||
2349 | @item :linger @var{linger-arg} | |
2350 | If @var{linger-arg} is non-@code{nil}, wait for successful | |
2351 | transmission of all queued packets on the connection before it is | |
2352 | deleted (see @code{delete-process}). If @var{linger-arg} is an | |
2353 | integer, it specifies the maximum time in seconds to wait for queued | |
016a35df GM |
2354 | packets to be sent before closing the connection. The default is |
2355 | @code{nil}, which means to discard unsent queued packets when the | |
b8d4c8d0 GM |
2356 | process is deleted. |
2357 | ||
016a35df | 2358 | @c FIXME Where out-of-band data is ...? |
b8d4c8d0 GM |
2359 | @item :oobinline @var{oobinline-flag} |
2360 | If @var{oobinline-flag} is non-@code{nil} for a stream connection, | |
2361 | receive out-of-band data in the normal data stream. Otherwise, ignore | |
2362 | out-of-band data. | |
2363 | ||
2364 | @item :priority @var{priority} | |
2365 | Set the priority for packets sent on this connection to the integer | |
2366 | @var{priority}. The interpretation of this number is protocol | |
016a35df | 2367 | specific; such as setting the TOS (type of service) field on IP |
b8d4c8d0 GM |
2368 | packets sent on this connection. It may also have system dependent |
2369 | effects, such as selecting a specific output queue on the network | |
2370 | interface. | |
2371 | ||
2372 | @item :reuseaddr @var{reuseaddr-flag} | |
2373 | If @var{reuseaddr-flag} is non-@code{nil} (the default) for a stream | |
2374 | server process, allow this server to reuse a specific port number (see | |
016a35df | 2375 | @code{:service}), unless another process on this host is already |
b8d4c8d0 GM |
2376 | listening on that port. If @var{reuseaddr-flag} is @code{nil}, there |
2377 | may be a period of time after the last use of that port (by any | |
016a35df | 2378 | process on the host) where it is not possible to make a new server on |
b8d4c8d0 GM |
2379 | that port. |
2380 | @end table | |
2381 | ||
106e6894 | 2382 | @defun set-network-process-option process option value &optional no-error |
b8d4c8d0 | 2383 | This function sets or modifies a network option for network process |
016a35df GM |
2384 | @var{process}. The accepted options and values are as for |
2385 | @code{make-network-process}. If @var{no-error} is non-@code{nil}, | |
2386 | this function returns @code{nil} instead of signaling an error if | |
2387 | @var{option} is not a supported option. If the function successfully | |
2388 | completes, it returns @code{t}. | |
b8d4c8d0 GM |
2389 | |
2390 | The current setting of an option is available via the | |
2391 | @code{process-contact} function. | |
2392 | @end defun | |
2393 | ||
2394 | @node Network Feature Testing | |
2395 | @subsection Testing Availability of Network Features | |
2396 | ||
2397 | To test for the availability of a given network feature, use | |
2398 | @code{featurep} like this: | |
2399 | ||
2400 | @example | |
2401 | (featurep 'make-network-process '(@var{keyword} @var{value})) | |
2402 | @end example | |
2403 | ||
2404 | @noindent | |
016a35df | 2405 | The result of this form is @code{t} if it works to specify |
b8d4c8d0 | 2406 | @var{keyword} with value @var{value} in @code{make-network-process}. |
016a35df | 2407 | Here are some of the @var{keyword}---@var{value} pairs you can test in |
b8d4c8d0 GM |
2408 | this way. |
2409 | ||
2410 | @table @code | |
2411 | @item (:nowait t) | |
2412 | Non-@code{nil} if non-blocking connect is supported. | |
2413 | @item (:type datagram) | |
2414 | Non-@code{nil} if datagrams are supported. | |
2415 | @item (:family local) | |
2416 | Non-@code{nil} if local (a.k.a.@: ``UNIX domain'') sockets are supported. | |
2417 | @item (:family ipv6) | |
2418 | Non-@code{nil} if IPv6 is supported. | |
2419 | @item (:service t) | |
2420 | Non-@code{nil} if the system can select the port for a server. | |
2421 | @end table | |
2422 | ||
2423 | To test for the availability of a given network option, use | |
2424 | @code{featurep} like this: | |
2425 | ||
2426 | @example | |
2427 | (featurep 'make-network-process '@var{keyword}) | |
2428 | @end example | |
2429 | ||
2430 | @noindent | |
016a35df GM |
2431 | The accepted @var{keyword} values are @code{:bindtodevice}, etc. |
2432 | For the complete list, @pxref{Network Options}. This form returns | |
2433 | non-@code{nil} if that particular network option is supported by | |
2434 | @code{make-network-process} (or @code{set-network-process-option}). | |
b8d4c8d0 GM |
2435 | |
2436 | @node Misc Network | |
2437 | @section Misc Network Facilities | |
2438 | ||
2439 | These additional functions are useful for creating and operating | |
305a7ef2 EZ |
2440 | on network connections. Note that they are supported only on some |
2441 | systems. | |
b8d4c8d0 GM |
2442 | |
2443 | @defun network-interface-list | |
2444 | This function returns a list describing the network interfaces | |
2445 | of the machine you are using. The value is an alist whose | |
2446 | elements have the form @code{(@var{name} . @var{address})}. | |
2447 | @var{address} has the same form as the @var{local-address} | |
2448 | and @var{remote-address} arguments to @code{make-network-process}. | |
2449 | @end defun | |
2450 | ||
2451 | @defun network-interface-info ifname | |
2452 | This function returns information about the network interface named | |
2453 | @var{ifname}. The value is a list of the form | |
2454 | @code{(@var{addr} @var{bcast} @var{netmask} @var{hwaddr} @var{flags})}. | |
2455 | ||
2456 | @table @var | |
2457 | @item addr | |
2458 | The Internet protocol address. | |
2459 | @item bcast | |
2460 | The broadcast address. | |
2461 | @item netmask | |
2462 | The network mask. | |
2463 | @item hwaddr | |
2464 | The layer 2 address (Ethernet MAC address, for instance). | |
2465 | @item flags | |
2466 | The current flags of the interface. | |
2467 | @end table | |
2468 | @end defun | |
2469 | ||
2470 | @defun format-network-address address &optional omit-port | |
2471 | This function converts the Lisp representation of a network address to | |
2472 | a string. | |
2473 | ||
2474 | A five-element vector @code{[@var{a} @var{b} @var{c} @var{d} @var{p}]} | |
2475 | represents an IPv4 address @var{a}.@var{b}.@var{c}.@var{d} and port | |
2476 | number @var{p}. @code{format-network-address} converts that to the | |
2477 | string @code{"@var{a}.@var{b}.@var{c}.@var{d}:@var{p}"}. | |
2478 | ||
2479 | A nine-element vector @code{[@var{a} @var{b} @var{c} @var{d} @var{e} | |
2480 | @var{f} @var{g} @var{h} @var{p}]} represents an IPv6 address along | |
2481 | with a port number. @code{format-network-address} converts that to | |
2482 | the string | |
2483 | @code{"[@var{a}:@var{b}:@var{c}:@var{d}:@var{e}:@var{f}:@var{g}:@var{h}]:@var{p}"}. | |
2484 | ||
2485 | If the vector does not include the port number, @var{p}, or if | |
2486 | @var{omit-port} is non-@code{nil}, the result does not include the | |
2487 | @code{:@var{p}} suffix. | |
2488 | @end defun | |
2489 | ||
c73e02fa GM |
2490 | @node Serial Ports |
2491 | @section Communicating with Serial Ports | |
2492 | @cindex @file{/dev/tty} | |
2493 | @cindex @file{COM1} | |
545c2782 | 2494 | @cindex serial connections |
c73e02fa GM |
2495 | |
2496 | Emacs can communicate with serial ports. For interactive use, | |
2497 | @kbd{M-x serial-term} opens a terminal window. In a Lisp program, | |
2498 | @code{make-serial-process} creates a process object. | |
2499 | ||
2500 | The serial port can be configured at run-time, without having to | |
2501 | close and re-open it. The function @code{serial-process-configure} | |
2502 | lets you change the speed, bytesize, and other parameters. In a | |
2503 | terminal window created by @code{serial-term}, you can click on the | |
2504 | mode line for configuration. | |
2505 | ||
4373fd43 GM |
2506 | A serial connection is represented by a process object, which can be |
2507 | used in a similar way to a subprocess or network process. You can send and | |
2508 | receive data, and configure the serial port. A serial process object | |
2509 | has no process ID, however, and you can't send signals to it, and the | |
2510 | status codes are different from other types of processes. | |
c73e02fa GM |
2511 | @code{delete-process} on the process object or @code{kill-buffer} on |
2512 | the process buffer close the connection, but this does not affect the | |
2513 | device connected to the serial port. | |
2514 | ||
2515 | The function @code{process-type} returns the symbol @code{serial} | |
80e6b6df | 2516 | for a process object representing a serial port connection. |
c73e02fa | 2517 | |
4373fd43 | 2518 | Serial ports are available on GNU/Linux, Unix, and MS Windows systems. |
c73e02fa | 2519 | |
80e6b6df | 2520 | @deffn Command serial-term port speed |
c73e02fa | 2521 | Start a terminal-emulator for a serial port in a new buffer. |
4373fd43 GM |
2522 | @var{port} is the name of the serial port to connect to. For |
2523 | example, this could be @file{/dev/ttyS0} on Unix. On MS Windows, this | |
80e6b6df EZ |
2524 | could be @file{COM1}, or @file{\\.\COM10} (double the backslashes in |
2525 | Lisp strings). | |
c73e02fa | 2526 | |
4373fd43 GM |
2527 | @c FIXME is 9600 still the most common value, or is it 115200 now? |
2528 | @c (Same value, 9600, appears below as well.) | |
c73e02fa | 2529 | @var{speed} is the speed of the serial port in bits per second. 9600 |
80e6b6df EZ |
2530 | is a common value. The buffer is in Term mode; see @ref{Term Mode,,, |
2531 | emacs, The GNU Emacs Manual}, for the commands to use in that buffer. | |
2532 | You can change the speed and the configuration in the mode line menu. | |
2533 | @end deffn | |
c73e02fa GM |
2534 | |
2535 | @defun make-serial-process &rest args | |
80e6b6df | 2536 | This function creates a process and a buffer. Arguments are specified |
4373fd43 GM |
2537 | as keyword/argument pairs. Here's the list of the meaningful |
2538 | keywords, with the first two (@var{port} and @var{speed}) being mandatory: | |
c73e02fa GM |
2539 | |
2540 | @table @code | |
4373fd43 | 2541 | @item :port @var{port} |
80e6b6df EZ |
2542 | This is the name of the serial port. On Unix and GNU systems, this is |
2543 | a file name such as @file{/dev/ttyS0}. On Windows, this could be | |
2544 | @file{COM1}, or @file{\\.\COM10} for ports higher than @file{COM9} | |
2545 | (double the backslashes in Lisp strings). | |
2546 | ||
4373fd43 | 2547 | @item :speed @var{speed} |
80e6b6df | 2548 | The speed of the serial port in bits per second. This function calls |
4373fd43 GM |
2549 | @code{serial-process-configure} to handle the speed; see the |
2550 | following documentation of that function for more details. | |
80e6b6df EZ |
2551 | |
2552 | @item :name @var{name} | |
2553 | The name of the process. If @var{name} is not given, @var{port} will | |
2554 | serve as the process name as well. | |
2555 | ||
2556 | @item :buffer @var{buffer} | |
4373fd43 | 2557 | The buffer to associate with the process. The value can be either a |
80e6b6df EZ |
2558 | buffer or a string that names a buffer. Process output goes at the |
2559 | end of that buffer, unless you specify an output stream or filter | |
2560 | function to handle the output. If @var{buffer} is not given, the | |
2561 | process buffer's name is taken from the value of the @code{:name} | |
2562 | keyword. | |
2563 | ||
2564 | @item :coding @var{coding} | |
c73e02fa GM |
2565 | If @var{coding} is a symbol, it specifies the coding system used for |
2566 | both reading and writing for this process. If @var{coding} is a cons | |
4373fd43 GM |
2567 | @code{(@var{decoding} . @var{encoding})}, @var{decoding} is used for |
2568 | reading, and @var{encoding} is used for writing. If not specified, | |
2569 | the default is to determine the coding systems from the data itself. | |
c73e02fa | 2570 | |
80e6b6df EZ |
2571 | @item :noquery @var{query-flag} |
2572 | Initialize the process query flag to @var{query-flag}. @xref{Query | |
2573 | Before Exit}. The flags defaults to @code{nil} if unspecified. | |
c73e02fa | 2574 | |
80e6b6df | 2575 | @item :stop @var{bool} |
016a35df | 2576 | Start process in the ``stopped'' state if @var{bool} is |
c73e02fa GM |
2577 | non-@code{nil}. In the stopped state, a serial process does not |
2578 | accept incoming data, but you can send outgoing data. The stopped | |
2579 | state is cleared by @code{continue-process} and set by | |
2580 | @code{stop-process}. | |
2581 | ||
80e6b6df | 2582 | @item :filter @var{filter} |
c73e02fa GM |
2583 | Install @var{filter} as the process filter. |
2584 | ||
80e6b6df | 2585 | @item :sentinel @var{sentinel} |
c73e02fa GM |
2586 | Install @var{sentinel} as the process sentinel. |
2587 | ||
80e6b6df | 2588 | @item :plist @var{plist} |
c73e02fa GM |
2589 | Install @var{plist} as the initial plist of the process. |
2590 | ||
4373fd43 | 2591 | @item :bytesize |
c73e02fa GM |
2592 | @itemx :parity |
2593 | @itemx :stopbits | |
2594 | @itemx :flowcontrol | |
049bcbcb CY |
2595 | These are handled by @code{serial-process-configure}, which is called |
2596 | by @code{make-serial-process}. | |
c73e02fa GM |
2597 | @end table |
2598 | ||
2599 | The original argument list, possibly modified by later configuration, | |
2600 | is available via the function @code{process-contact}. | |
2601 | ||
049bcbcb | 2602 | Here is an example: |
c73e02fa GM |
2603 | |
2604 | @example | |
2605 | (make-serial-process :port "/dev/ttyS0" :speed 9600) | |
c73e02fa GM |
2606 | @end example |
2607 | @end defun | |
2608 | ||
2609 | @defun serial-process-configure &rest args | |
80e6b6df EZ |
2610 | @cindex baud, in serial connections |
2611 | @cindex bytesize, in serial connections | |
2612 | @cindex parity, in serial connections | |
2613 | @cindex stopbits, in serial connections | |
2614 | @cindex flowcontrol, in serial connections | |
2615 | ||
2616 | This functions configures a serial port connection. Arguments are | |
2617 | specified as keyword/argument pairs. Attributes that are not given | |
2618 | are re-initialized from the process's current configuration (available | |
4373fd43 | 2619 | via the function @code{process-contact}), or set to reasonable default |
80e6b6df | 2620 | values. The following arguments are defined: |
c73e02fa GM |
2621 | |
2622 | @table @code | |
80e6b6df EZ |
2623 | @item :process @var{process} |
2624 | @itemx :name @var{name} | |
2625 | @itemx :buffer @var{buffer} | |
2626 | @itemx :port @var{port} | |
c73e02fa GM |
2627 | Any of these arguments can be given to identify the process that is to |
2628 | be configured. If none of these arguments is given, the current | |
2629 | buffer's process is used. | |
2630 | ||
2631 | @item :speed @var{speed} | |
545c2782 EZ |
2632 | The speed of the serial port in bits per second, a.k.a.@: @dfn{baud |
2633 | rate}. The value can be any number, but most serial ports work only | |
2634 | at a few defined values between 1200 and 115200, with 9600 being the | |
2635 | most common value. If @var{speed} is @code{nil}, the function ignores | |
2636 | all other arguments and does not configure the port. This may be | |
4373fd43 GM |
2637 | useful for special serial ports such as Bluetooth-to-serial converters, |
2638 | which can only be configured through @samp{AT} commands sent through the | |
538395d9 EZ |
2639 | connection. The value of @code{nil} for @var{speed} is valid only for |
2640 | connections that were already opened by a previous call to | |
80e6b6df | 2641 | @code{make-serial-process} or @code{serial-term}. |
c73e02fa GM |
2642 | |
2643 | @item :bytesize @var{bytesize} | |
80e6b6df EZ |
2644 | The number of bits per byte, which can be 7 or 8. If @var{bytesize} |
2645 | is not given or @code{nil}, it defaults to 8. | |
c73e02fa GM |
2646 | |
2647 | @item :parity @var{parity} | |
80e6b6df | 2648 | The value can be @code{nil} (don't use parity), the symbol |
c73e02fa | 2649 | @code{odd} (use odd parity), or the symbol @code{even} (use even |
80e6b6df | 2650 | parity). If @var{parity} is not given, it defaults to no parity. |
c73e02fa GM |
2651 | |
2652 | @item :stopbits @var{stopbits} | |
80e6b6df EZ |
2653 | The number of stopbits used to terminate a transmission |
2654 | of each byte. @var{stopbits} can be 1 or 2. If @var{stopbits} is not | |
2655 | given or @code{nil}, it defaults to 1. | |
c73e02fa GM |
2656 | |
2657 | @item :flowcontrol @var{flowcontrol} | |
80e6b6df EZ |
2658 | The type of flow control to use for this connection, which is either |
2659 | @code{nil} (don't use flow control), the symbol @code{hw} (use RTS/CTS | |
2660 | hardware flow control), or the symbol @code{sw} (use XON/XOFF software | |
2661 | flow control). If @var{flowcontrol} is not given, it defaults to no | |
2662 | flow control. | |
c73e02fa GM |
2663 | @end table |
2664 | ||
4373fd43 GM |
2665 | Internally, @code{make-serial-process} calls |
2666 | @code{serial-process-configure} for the initial configuration of the | |
2667 | serial port. | |
c73e02fa GM |
2668 | @end defun |
2669 | ||
b8d4c8d0 GM |
2670 | @node Byte Packing |
2671 | @section Packing and Unpacking Byte Arrays | |
2672 | @cindex byte packing and unpacking | |
2673 | ||
2674 | This section describes how to pack and unpack arrays of bytes, | |
2675 | usually for binary network protocols. These functions convert byte arrays | |
2676 | to alists, and vice versa. The byte array can be represented as a | |
4373fd43 | 2677 | @c FIXME? No multibyte? |
b8d4c8d0 GM |
2678 | unibyte string or as a vector of integers, while the alist associates |
2679 | symbols either with fixed-size objects or with recursive sub-alists. | |
4373fd43 GM |
2680 | To use the functions referred to in this section, load the |
2681 | @code{bindat} library. | |
2682 | @c It doesn't have any autoloads. | |
b8d4c8d0 GM |
2683 | |
2684 | @cindex serializing | |
2685 | @cindex deserializing | |
2686 | @cindex packing | |
2687 | @cindex unpacking | |
2688 | Conversion from byte arrays to nested alists is also known as | |
2689 | @dfn{deserializing} or @dfn{unpacking}, while going in the opposite | |
2690 | direction is also known as @dfn{serializing} or @dfn{packing}. | |
2691 | ||
2692 | @menu | |
2693 | * Bindat Spec:: Describing data layout. | |
2694 | * Bindat Functions:: Doing the unpacking and packing. | |
2695 | * Bindat Examples:: Samples of what bindat.el can do for you! | |
2696 | @end menu | |
2697 | ||
2698 | @node Bindat Spec | |
2699 | @subsection Describing Data Layout | |
2700 | ||
2701 | To control unpacking and packing, you write a @dfn{data layout | |
2702 | specification}, a special nested list describing named and typed | |
4373fd43 | 2703 | @dfn{fields}. This specification controls the length of each field to be |
b8d4c8d0 GM |
2704 | processed, and how to pack or unpack it. We normally keep bindat specs |
2705 | in variables whose names end in @samp{-bindat-spec}; that kind of name | |
e153c136 | 2706 | is automatically recognized as ``risky''. |
b8d4c8d0 GM |
2707 | |
2708 | @cindex endianness | |
2709 | @cindex big endian | |
2710 | @cindex little endian | |
2711 | @cindex network byte ordering | |
2712 | A field's @dfn{type} describes the size (in bytes) of the object | |
2713 | that the field represents and, in the case of multibyte fields, how | |
2714 | the bytes are ordered within the field. The two possible orderings | |
2715 | are ``big endian'' (also known as ``network byte ordering'') and | |
e153c136 | 2716 | ``little endian''. For instance, the number @code{#x23cd} (decimal |
b8d4c8d0 GM |
2717 | 9165) in big endian would be the two bytes @code{#x23} @code{#xcd}; |
2718 | and in little endian, @code{#xcd} @code{#x23}. Here are the possible | |
2719 | type values: | |
2720 | ||
2721 | @table @code | |
2722 | @item u8 | |
2723 | @itemx byte | |
2724 | Unsigned byte, with length 1. | |
2725 | ||
2726 | @item u16 | |
2727 | @itemx word | |
2728 | @itemx short | |
2729 | Unsigned integer in network byte order, with length 2. | |
2730 | ||
2731 | @item u24 | |
2732 | Unsigned integer in network byte order, with length 3. | |
2733 | ||
2734 | @item u32 | |
2735 | @itemx dword | |
2736 | @itemx long | |
2737 | Unsigned integer in network byte order, with length 4. | |
44e97401 | 2738 | Note: These values may be limited by Emacs's integer implementation limits. |
b8d4c8d0 GM |
2739 | |
2740 | @item u16r | |
2741 | @itemx u24r | |
2742 | @itemx u32r | |
2743 | Unsigned integer in little endian order, with length 2, 3 and 4, respectively. | |
2744 | ||
2745 | @item str @var{len} | |
2746 | String of length @var{len}. | |
2747 | ||
2748 | @item strz @var{len} | |
2749 | Zero-terminated string, in a fixed-size field with length @var{len}. | |
2750 | ||
2751 | @item vec @var{len} [@var{type}] | |
4373fd43 | 2752 | Vector of @var{len} elements of type @var{type}, defaulting to bytes. |
b8d4c8d0 | 2753 | The @var{type} is any of the simple types above, or another vector |
4373fd43 | 2754 | specified as a list of the form @code{(vec @var{len} [@var{type}])}. |
b8d4c8d0 GM |
2755 | |
2756 | @item ip | |
4373fd43 | 2757 | @c FIXME? IPv6? |
b8d4c8d0 GM |
2758 | Four-byte vector representing an Internet address. For example: |
2759 | @code{[127 0 0 1]} for localhost. | |
2760 | ||
2761 | @item bits @var{len} | |
2762 | List of set bits in @var{len} bytes. The bytes are taken in big | |
2763 | endian order and the bits are numbered starting with @code{8 * | |
2764 | @var{len} @minus{} 1} and ending with zero. For example: @code{bits | |
2765 | 2} unpacks @code{#x28} @code{#x1c} to @code{(2 3 4 11 13)} and | |
2766 | @code{#x1c} @code{#x28} to @code{(3 5 10 11 12)}. | |
2767 | ||
2768 | @item (eval @var{form}) | |
2769 | @var{form} is a Lisp expression evaluated at the moment the field is | |
2770 | unpacked or packed. The result of the evaluation should be one of the | |
2771 | above-listed type specifications. | |
2772 | @end table | |
2773 | ||
2774 | For a fixed-size field, the length @var{len} is given as an integer | |
2775 | specifying the number of bytes in the field. | |
2776 | ||
2777 | When the length of a field is not fixed, it typically depends on the | |
2778 | value of a preceding field. In this case, the length @var{len} can be | |
2779 | given either as a list @code{(@var{name} ...)} identifying a | |
2780 | @dfn{field name} in the format specified for @code{bindat-get-field} | |
2781 | below, or by an expression @code{(eval @var{form})} where @var{form} | |
2782 | should evaluate to an integer, specifying the field length. | |
2783 | ||
2784 | A field specification generally has the form @code{([@var{name}] | |
4373fd43 GM |
2785 | @var{handler})}, where @var{name} is optional. Don't use names that |
2786 | are symbols meaningful as type specifications (above) or handler | |
2787 | specifications (below), since that would be ambiguous. @var{name} can | |
2788 | be a symbol or an expression @code{(eval @var{form})}, in which case | |
2789 | @var{form} should evaluate to a symbol. | |
b8d4c8d0 GM |
2790 | |
2791 | @var{handler} describes how to unpack or pack the field and can be one | |
2792 | of the following: | |
2793 | ||
2794 | @table @code | |
2795 | @item @var{type} | |
2796 | Unpack/pack this field according to the type specification @var{type}. | |
2797 | ||
2798 | @item eval @var{form} | |
2799 | Evaluate @var{form}, a Lisp expression, for side-effect only. If the | |
2800 | field name is specified, the value is bound to that field name. | |
2801 | ||
2802 | @item fill @var{len} | |
2803 | Skip @var{len} bytes. In packing, this leaves them unchanged, | |
2804 | which normally means they remain zero. In unpacking, this means | |
2805 | they are ignored. | |
2806 | ||
2807 | @item align @var{len} | |
2808 | Skip to the next multiple of @var{len} bytes. | |
2809 | ||
2810 | @item struct @var{spec-name} | |
2811 | Process @var{spec-name} as a sub-specification. This describes a | |
2812 | structure nested within another structure. | |
2813 | ||
2814 | @item union @var{form} (@var{tag} @var{spec})@dots{} | |
2815 | @c ??? I don't see how one would actually use this. | |
2816 | @c ??? what kind of expression would be useful for @var{form}? | |
2817 | Evaluate @var{form}, a Lisp expression, find the first @var{tag} | |
2818 | that matches it, and process its associated data layout specification | |
2819 | @var{spec}. Matching can occur in one of three ways: | |
2820 | ||
2821 | @itemize | |
2822 | @item | |
2823 | If a @var{tag} has the form @code{(eval @var{expr})}, evaluate | |
2824 | @var{expr} with the variable @code{tag} dynamically bound to the value | |
2825 | of @var{form}. A non-@code{nil} result indicates a match. | |
2826 | ||
2827 | @item | |
2828 | @var{tag} matches if it is @code{equal} to the value of @var{form}. | |
2829 | ||
2830 | @item | |
2831 | @var{tag} matches unconditionally if it is @code{t}. | |
2832 | @end itemize | |
2833 | ||
2834 | @item repeat @var{count} @var{field-specs}@dots{} | |
2835 | Process the @var{field-specs} recursively, in order, then repeat | |
4373fd43 | 2836 | starting from the first one, processing all the specifications @var{count} |
b8d4c8d0 GM |
2837 | times overall. The @var{count} is given using the same formats as a |
2838 | field length---if an @code{eval} form is used, it is evaluated just once. | |
4373fd43 GM |
2839 | For correct operation, each specification in @var{field-specs} must |
2840 | include a name. | |
b8d4c8d0 GM |
2841 | @end table |
2842 | ||
2843 | For the @code{(eval @var{form})} forms used in a bindat specification, | |
2844 | the @var{form} can access and update these dynamically bound variables | |
2845 | during evaluation: | |
2846 | ||
2847 | @table @code | |
2848 | @item last | |
2849 | Value of the last field processed. | |
2850 | ||
2851 | @item bindat-raw | |
2852 | The data as a byte array. | |
2853 | ||
2854 | @item bindat-idx | |
2855 | Current index (within @code{bindat-raw}) for unpacking or packing. | |
2856 | ||
2857 | @item struct | |
2858 | The alist containing the structured data that have been unpacked so | |
2859 | far, or the entire structure being packed. You can use | |
2860 | @code{bindat-get-field} to access specific fields of this structure. | |
2861 | ||
2862 | @item count | |
2863 | @itemx index | |
2864 | Inside a @code{repeat} block, these contain the maximum number of | |
2865 | repetitions (as specified by the @var{count} parameter), and the | |
2866 | current repetition number (counting from 0). Setting @code{count} to | |
2867 | zero will terminate the inner-most repeat block after the current | |
2868 | repetition has completed. | |
2869 | @end table | |
2870 | ||
2871 | @node Bindat Functions | |
2872 | @subsection Functions to Unpack and Pack Bytes | |
2873 | ||
2874 | In the following documentation, @var{spec} refers to a data layout | |
2875 | specification, @code{bindat-raw} to a byte array, and @var{struct} to an | |
2876 | alist representing unpacked field data. | |
2877 | ||
2878 | @defun bindat-unpack spec bindat-raw &optional bindat-idx | |
4373fd43 | 2879 | @c FIXME? Again, no multibyte? |
b8d4c8d0 GM |
2880 | This function unpacks data from the unibyte string or byte |
2881 | array @code{bindat-raw} | |
4373fd43 | 2882 | according to @var{spec}. Normally, this starts unpacking at the |
b8d4c8d0 GM |
2883 | beginning of the byte array, but if @var{bindat-idx} is non-@code{nil}, it |
2884 | specifies a zero-based starting position to use instead. | |
2885 | ||
2886 | The value is an alist or nested alist in which each element describes | |
2887 | one unpacked field. | |
2888 | @end defun | |
2889 | ||
2890 | @defun bindat-get-field struct &rest name | |
2891 | This function selects a field's data from the nested alist | |
2892 | @var{struct}. Usually @var{struct} was returned by | |
2893 | @code{bindat-unpack}. If @var{name} corresponds to just one argument, | |
2894 | that means to extract a top-level field value. Multiple @var{name} | |
2895 | arguments specify repeated lookup of sub-structures. An integer name | |
2896 | acts as an array index. | |
2897 | ||
2898 | For example, if @var{name} is @code{(a b 2 c)}, that means to find | |
2899 | field @code{c} in the third element of subfield @code{b} of field | |
2900 | @code{a}. (This corresponds to @code{struct.a.b[2].c} in C.) | |
2901 | @end defun | |
2902 | ||
2903 | Although packing and unpacking operations change the organization of | |
2904 | data (in memory), they preserve the data's @dfn{total length}, which is | |
2905 | the sum of all the fields' lengths, in bytes. This value is not | |
2906 | generally inherent in either the specification or alist alone; instead, | |
2907 | both pieces of information contribute to its calculation. Likewise, the | |
2908 | length of a string or array being unpacked may be longer than the data's | |
2909 | total length as described by the specification. | |
2910 | ||
2911 | @defun bindat-length spec struct | |
2912 | This function returns the total length of the data in @var{struct}, | |
2913 | according to @var{spec}. | |
2914 | @end defun | |
2915 | ||
2916 | @defun bindat-pack spec struct &optional bindat-raw bindat-idx | |
2917 | This function returns a byte array packed according to @var{spec} from | |
4373fd43 | 2918 | the data in the alist @var{struct}. It normally creates and fills a |
b8d4c8d0 GM |
2919 | new byte array starting at the beginning. However, if @var{bindat-raw} |
2920 | is non-@code{nil}, it specifies a pre-allocated unibyte string or vector to | |
2921 | pack into. If @var{bindat-idx} is non-@code{nil}, it specifies the starting | |
2922 | offset for packing into @code{bindat-raw}. | |
2923 | ||
2924 | When pre-allocating, you should make sure @code{(length @var{bindat-raw})} | |
2925 | meets or exceeds the total length to avoid an out-of-range error. | |
2926 | @end defun | |
2927 | ||
2928 | @defun bindat-ip-to-string ip | |
2929 | Convert the Internet address vector @var{ip} to a string in the usual | |
2930 | dotted notation. | |
4373fd43 | 2931 | @c FIXME? Does it do IPv6? |
b8d4c8d0 GM |
2932 | |
2933 | @example | |
2934 | (bindat-ip-to-string [127 0 0 1]) | |
2935 | @result{} "127.0.0.1" | |
2936 | @end example | |
2937 | @end defun | |
2938 | ||
2939 | @node Bindat Examples | |
2940 | @subsection Examples of Byte Unpacking and Packing | |
4373fd43 GM |
2941 | @c FIXME? This seems a very long example for something that is not used |
2942 | @c very often. As of 24.1, gdb-mi.el is the only user of bindat.el in Emacs. | |
2943 | @c Maybe one or both of these examples should just be moved to the | |
2944 | @c commentary of bindat.el. | |
b8d4c8d0 GM |
2945 | |
2946 | Here is a complete example of byte unpacking and packing: | |
2947 | ||
2948 | @lisp | |
4373fd43 GM |
2949 | (require 'bindat) |
2950 | ||
b8d4c8d0 GM |
2951 | (defvar fcookie-index-spec |
2952 | '((:version u32) | |
2953 | (:count u32) | |
2954 | (:longest u32) | |
2955 | (:shortest u32) | |
2956 | (:flags u32) | |
2957 | (:delim u8) | |
2958 | (:ignored fill 3) | |
4373fd43 | 2959 | (:offset repeat (:count) (:foo u32))) |
b8d4c8d0 GM |
2960 | "Description of a fortune cookie index file's contents.") |
2961 | ||
2962 | (defun fcookie (cookies &optional index) | |
2963 | "Display a random fortune cookie from file COOKIES. | |
2964 | Optional second arg INDEX specifies the associated index | |
4373fd43 GM |
2965 | filename, by default \"COOKIES.dat\". Display cookie text |
2966 | in buffer \"*Fortune Cookie: BASENAME*\", where BASENAME | |
b8d4c8d0 GM |
2967 | is COOKIES without the directory part." |
2968 | (interactive "fCookies file: ") | |
2969 | (let* ((info (with-temp-buffer | |
2970 | (insert-file-contents-literally | |
2971 | (or index (concat cookies ".dat"))) | |
2972 | (bindat-unpack fcookie-index-spec | |
2973 | (buffer-string)))) | |
2974 | (sel (random (bindat-get-field info :count))) | |
2975 | (beg (cdar (bindat-get-field info :offset sel))) | |
2976 | (end (or (cdar (bindat-get-field info | |
2977 | :offset (1+ sel))) | |
2978 | (nth 7 (file-attributes cookies))))) | |
2979 | (switch-to-buffer | |
2980 | (get-buffer-create | |
2981 | (format "*Fortune Cookie: %s*" | |
2982 | (file-name-nondirectory cookies)))) | |
2983 | (erase-buffer) | |
2984 | (insert-file-contents-literally | |
2985 | cookies nil beg (- end 3)))) | |
2986 | ||
2987 | (defun fcookie-create-index (cookies &optional index delim) | |
2988 | "Scan file COOKIES, and write out its index file. | |
4373fd43 GM |
2989 | Optional arg INDEX specifies the index filename, which by |
2990 | default is \"COOKIES.dat\". Optional arg DELIM specifies the | |
2991 | unibyte character that, when found on a line of its own in | |
b8d4c8d0 GM |
2992 | COOKIES, indicates the border between entries." |
2993 | (interactive "fCookies file: ") | |
2994 | (setq delim (or delim ?%)) | |
2995 | (let ((delim-line (format "\n%c\n" delim)) | |
2996 | (count 0) | |
2997 | (max 0) | |
2998 | min p q len offsets) | |
2999 | (unless (= 3 (string-bytes delim-line)) | |
3000 | (error "Delimiter cannot be represented in one byte")) | |
3001 | (with-temp-buffer | |
3002 | (insert-file-contents-literally cookies) | |
3003 | (while (and (setq p (point)) | |
3004 | (search-forward delim-line (point-max) t) | |
3005 | (setq len (- (point) 3 p))) | |
3006 | (setq count (1+ count) | |
3007 | max (max max len) | |
3008 | min (min (or min max) len) | |
3009 | offsets (cons (1- p) offsets)))) | |
3010 | (with-temp-buffer | |
3011 | (set-buffer-multibyte nil) | |
3012 | (insert | |
3013 | (bindat-pack | |
3014 | fcookie-index-spec | |
3015 | `((:version . 2) | |
3016 | (:count . ,count) | |
3017 | (:longest . ,max) | |
3018 | (:shortest . ,min) | |
3019 | (:flags . 0) | |
3020 | (:delim . ,delim) | |
3021 | (:offset . ,(mapcar (lambda (o) | |
3022 | (list (cons :foo o))) | |
3023 | (nreverse offsets)))))) | |
3024 | (let ((coding-system-for-write 'raw-text-unix)) | |
3025 | (write-file (or index (concat cookies ".dat"))))))) | |
3026 | @end lisp | |
3027 | ||
4373fd43 GM |
3028 | The following is an example of defining and unpacking a complex |
3029 | structure. Consider the following C structures: | |
b8d4c8d0 GM |
3030 | |
3031 | @example | |
3032 | struct header @{ | |
3033 | unsigned long dest_ip; | |
3034 | unsigned long src_ip; | |
3035 | unsigned short dest_port; | |
3036 | unsigned short src_port; | |
3037 | @}; | |
3038 | ||
3039 | struct data @{ | |
3040 | unsigned char type; | |
3041 | unsigned char opcode; | |
4373fd43 | 3042 | unsigned short length; /* in network byte order */ |
b8d4c8d0 GM |
3043 | unsigned char id[8]; /* null-terminated string */ |
3044 | unsigned char data[/* (length + 3) & ~3 */]; | |
3045 | @}; | |
3046 | ||
3047 | struct packet @{ | |
3048 | struct header header; | |
4373fd43 | 3049 | unsigned long counters[2]; /* in little endian order */ |
b8d4c8d0 GM |
3050 | unsigned char items; |
3051 | unsigned char filler[3]; | |
3052 | struct data item[/* items */]; | |
3053 | ||
3054 | @}; | |
3055 | @end example | |
3056 | ||
4373fd43 | 3057 | The corresponding data layout specification is: |
b8d4c8d0 GM |
3058 | |
3059 | @lisp | |
3060 | (setq header-spec | |
3061 | '((dest-ip ip) | |
3062 | (src-ip ip) | |
3063 | (dest-port u16) | |
3064 | (src-port u16))) | |
3065 | ||
3066 | (setq data-spec | |
3067 | '((type u8) | |
3068 | (opcode u8) | |
4373fd43 | 3069 | (length u16) ; network byte order |
b8d4c8d0 GM |
3070 | (id strz 8) |
3071 | (data vec (length)) | |
3072 | (align 4))) | |
3073 | ||
3074 | (setq packet-spec | |
3075 | '((header struct header-spec) | |
4373fd43 | 3076 | (counters vec 2 u32r) ; little endian order |
b8d4c8d0 GM |
3077 | (items u8) |
3078 | (fill 3) | |
3079 | (item repeat (items) | |
3080 | (struct data-spec)))) | |
3081 | @end lisp | |
3082 | ||
4373fd43 | 3083 | A binary data representation is: |
b8d4c8d0 GM |
3084 | |
3085 | @lisp | |
3086 | (setq binary-data | |
3087 | [ 192 168 1 100 192 168 1 101 01 28 21 32 | |
3088 | 160 134 1 0 5 1 0 0 2 0 0 0 | |
3089 | 2 3 0 5 ?A ?B ?C ?D ?E ?F 0 0 1 2 3 4 5 0 0 0 | |
3090 | 1 4 0 7 ?B ?C ?D ?E ?F ?G 0 0 6 7 8 9 10 11 12 0 ]) | |
3091 | @end lisp | |
3092 | ||
4373fd43 | 3093 | The corresponding decoded structure is: |
b8d4c8d0 GM |
3094 | |
3095 | @lisp | |
3096 | (setq decoded (bindat-unpack packet-spec binary-data)) | |
3097 | @result{} | |
3098 | ((header | |
3099 | (dest-ip . [192 168 1 100]) | |
3100 | (src-ip . [192 168 1 101]) | |
3101 | (dest-port . 284) | |
3102 | (src-port . 5408)) | |
3103 | (counters . [100000 261]) | |
3104 | (items . 2) | |
3105 | (item ((data . [1 2 3 4 5]) | |
3106 | (id . "ABCDEF") | |
3107 | (length . 5) | |
3108 | (opcode . 3) | |
3109 | (type . 2)) | |
3110 | ((data . [6 7 8 9 10 11 12]) | |
3111 | (id . "BCDEFG") | |
3112 | (length . 7) | |
3113 | (opcode . 4) | |
3114 | (type . 1)))) | |
3115 | @end lisp | |
3116 | ||
4373fd43 | 3117 | An example of fetching data from this structure: |
b8d4c8d0 GM |
3118 | |
3119 | @lisp | |
3120 | (bindat-get-field decoded 'item 1 'id) | |
3121 | @result{} "BCDEFG" | |
3122 | @end lisp |