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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001, | |
57ebf0be | 4 | @c 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc. |
b8d4c8d0 | 5 | @c See the file elisp.texi for copying conditions. |
6336d8c3 | 6 | @setfilename ../../info/processes |
b8d4c8d0 GM |
7 | @node Processes, Display, Abbrevs, Top |
8 | @chapter Processes | |
9 | @cindex child process | |
10 | @cindex parent process | |
11 | @cindex subprocess | |
12 | @cindex process | |
13 | ||
14 | In the terminology of operating systems, a @dfn{process} is a space in | |
15 | which a program can execute. Emacs runs in a process. Emacs Lisp | |
16 | programs can invoke other programs in processes of their own. These are | |
17 | called @dfn{subprocesses} or @dfn{child processes} of the Emacs process, | |
18 | which is their @dfn{parent process}. | |
19 | ||
20 | A subprocess of Emacs may be @dfn{synchronous} or @dfn{asynchronous}, | |
21 | depending on how it is created. When you create a synchronous | |
22 | subprocess, the Lisp program waits for the subprocess to terminate | |
23 | before continuing execution. When you create an asynchronous | |
24 | subprocess, it can run in parallel with the Lisp program. This kind of | |
25 | subprocess is represented within Emacs by a Lisp object which is also | |
26 | called a ``process.'' Lisp programs can use this object to communicate | |
27 | with the subprocess or to control it. For example, you can send | |
28 | signals, obtain status information, receive output from the process, or | |
29 | send input to it. | |
30 | ||
31 | @defun processp object | |
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32 | This function returns @code{t} if @var{object} represents an Emacs |
33 | subprocess, @code{nil} otherwise. | |
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34 | @end defun |
35 | ||
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36 | In addition to subprocesses of the current Emacs session, you can |
37 | also access other processes running on your machine. @xref{System | |
38 | Processes}. | |
39 | ||
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40 | @menu |
41 | * Subprocess Creation:: Functions that start subprocesses. | |
42 | * Shell Arguments:: Quoting an argument to pass it to a shell. | |
43 | * Synchronous Processes:: Details of using synchronous subprocesses. | |
44 | * Asynchronous Processes:: Starting up an asynchronous subprocess. | |
45 | * Deleting Processes:: Eliminating an asynchronous subprocess. | |
46 | * Process Information:: Accessing run-status and other attributes. | |
47 | * Input to Processes:: Sending input to an asynchronous subprocess. | |
48 | * Signals to Processes:: Stopping, continuing or interrupting | |
49 | an asynchronous subprocess. | |
50 | * Output from Processes:: Collecting output from an asynchronous subprocess. | |
51 | * Sentinels:: Sentinels run when process run-status changes. | |
52 | * Query Before Exit:: Whether to query if exiting will kill a process. | |
23dd4ecd | 53 | * System Processes:: Accessing other processes running on your system. |
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54 | * Transaction Queues:: Transaction-based communication with subprocesses. |
55 | * Network:: Opening network connections. | |
56 | * Network Servers:: Network servers let Emacs accept net connections. | |
57 | * Datagrams:: UDP network connections. | |
58 | * Low-Level Network:: Lower-level but more general function | |
59 | to create connections and servers. | |
60 | * Misc Network:: Additional relevant functions for network connections. | |
c73e02fa | 61 | * Serial Ports:: Communicating with serial ports. |
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62 | * Byte Packing:: Using bindat to pack and unpack binary data. |
63 | @end menu | |
64 | ||
65 | @node Subprocess Creation | |
66 | @section Functions that Create Subprocesses | |
67 | ||
583d8b3c | 68 | There are three primitives that create a new subprocess in which to run |
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69 | a program. One of them, @code{start-process}, creates an asynchronous |
70 | process and returns a process object (@pxref{Asynchronous Processes}). | |
71 | The other two, @code{call-process} and @code{call-process-region}, | |
72 | create a synchronous process and do not return a process object | |
73 | (@pxref{Synchronous Processes}). | |
74 | ||
75 | Synchronous and asynchronous processes are explained in the following | |
76 | sections. Since the three functions are all called in a similar | |
77 | fashion, their common arguments are described here. | |
78 | ||
79 | @cindex execute program | |
80 | @cindex @code{PATH} environment variable | |
81 | @cindex @code{HOME} environment variable | |
82 | In all cases, the function's @var{program} argument specifies the | |
83 | program to be run. An error is signaled if the file is not found or | |
84 | cannot be executed. If the file name is relative, the variable | |
85 | @code{exec-path} contains a list of directories to search. Emacs | |
86 | initializes @code{exec-path} when it starts up, based on the value of | |
87 | the environment variable @code{PATH}. The standard file name | |
88 | constructs, @samp{~}, @samp{.}, and @samp{..}, are interpreted as | |
89 | usual in @code{exec-path}, but environment variable substitutions | |
90 | (@samp{$HOME}, etc.) are not recognized; use | |
91 | @code{substitute-in-file-name} to perform them (@pxref{File Name | |
92 | Expansion}). @code{nil} in this list refers to | |
93 | @code{default-directory}. | |
94 | ||
95 | Executing a program can also try adding suffixes to the specified | |
96 | name: | |
97 | ||
98 | @defvar exec-suffixes | |
99 | This variable is a list of suffixes (strings) to try adding to the | |
100 | specified program file name. The list should include @code{""} if you | |
101 | want the name to be tried exactly as specified. The default value is | |
102 | system-dependent. | |
103 | @end defvar | |
104 | ||
105 | @strong{Please note:} The argument @var{program} contains only the | |
106 | name of the program; it may not contain any command-line arguments. You | |
107 | must use @var{args} to provide those. | |
108 | ||
109 | Each of the subprocess-creating functions has a @var{buffer-or-name} | |
110 | argument which specifies where the standard output from the program will | |
111 | go. It should be a buffer or a buffer name; if it is a buffer name, | |
112 | that will create the buffer if it does not already exist. It can also | |
113 | be @code{nil}, which says to discard the output unless a filter function | |
114 | handles it. (@xref{Filter Functions}, and @ref{Read and Print}.) | |
115 | Normally, you should avoid having multiple processes send output to the | |
116 | same buffer because their output would be intermixed randomly. | |
117 | ||
118 | @cindex program arguments | |
119 | All three of the subprocess-creating functions have a @code{&rest} | |
120 | argument, @var{args}. The @var{args} must all be strings, and they are | |
121 | supplied to @var{program} as separate command line arguments. Wildcard | |
122 | characters and other shell constructs have no special meanings in these | |
123 | strings, since the strings are passed directly to the specified program. | |
124 | ||
125 | The subprocess gets its current directory from the value of | |
126 | @code{default-directory} (@pxref{File Name Expansion}). | |
127 | ||
128 | @cindex environment variables, subprocesses | |
129 | The subprocess inherits its environment from Emacs, but you can | |
130 | specify overrides for it with @code{process-environment}. @xref{System | |
131 | Environment}. | |
132 | ||
133 | @defvar exec-directory | |
134 | @pindex movemail | |
135 | The value of this variable is a string, the name of a directory that | |
136 | contains programs that come with GNU Emacs, programs intended for Emacs | |
137 | to invoke. The program @code{movemail} is an example of such a program; | |
138 | Rmail uses it to fetch new mail from an inbox. | |
139 | @end defvar | |
140 | ||
141 | @defopt exec-path | |
142 | The value of this variable is a list of directories to search for | |
143 | programs to run in subprocesses. Each element is either the name of a | |
144 | directory (i.e., a string), or @code{nil}, which stands for the default | |
145 | directory (which is the value of @code{default-directory}). | |
146 | @cindex program directories | |
147 | ||
148 | The value of @code{exec-path} is used by @code{call-process} and | |
149 | @code{start-process} when the @var{program} argument is not an absolute | |
150 | file name. | |
151 | @end defopt | |
152 | ||
153 | @node Shell Arguments | |
154 | @section Shell Arguments | |
155 | @cindex arguments for shell commands | |
156 | @cindex shell command arguments | |
157 | ||
158 | Lisp programs sometimes need to run a shell and give it a command | |
159 | that contains file names that were specified by the user. These | |
160 | programs ought to be able to support any valid file name. But the shell | |
161 | gives special treatment to certain characters, and if these characters | |
162 | occur in the file name, they will confuse the shell. To handle these | |
163 | characters, use the function @code{shell-quote-argument}: | |
164 | ||
165 | @defun shell-quote-argument argument | |
166 | This function returns a string which represents, in shell syntax, | |
167 | an argument whose actual contents are @var{argument}. It should | |
168 | work reliably to concatenate the return value into a shell command | |
169 | and then pass it to a shell for execution. | |
170 | ||
171 | Precisely what this function does depends on your operating system. The | |
172 | function is designed to work with the syntax of your system's standard | |
173 | shell; if you use an unusual shell, you will need to redefine this | |
174 | function. | |
175 | ||
176 | @example | |
177 | ;; @r{This example shows the behavior on GNU and Unix systems.} | |
178 | (shell-quote-argument "foo > bar") | |
179 | @result{} "foo\\ \\>\\ bar" | |
180 | ||
181 | ;; @r{This example shows the behavior on MS-DOS and MS-Windows.} | |
182 | (shell-quote-argument "foo > bar") | |
183 | @result{} "\"foo > bar\"" | |
184 | @end example | |
185 | ||
186 | Here's an example of using @code{shell-quote-argument} to construct | |
187 | a shell command: | |
188 | ||
189 | @example | |
190 | (concat "diff -c " | |
191 | (shell-quote-argument oldfile) | |
192 | " " | |
193 | (shell-quote-argument newfile)) | |
194 | @end example | |
195 | @end defun | |
196 | ||
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197 | @cindex quoting and unquoting shell command line |
198 | The following two functions help creating shell commands from | |
199 | individual argument strings and taking shell command lines apart into | |
200 | individual arguments. | |
201 | ||
202 | @defun split-string-and-unquote string &optional separators | |
203 | This function splits @var{string} into substrings at matches for the | |
204 | regular expression @var{separators}, like @code{split-string} does | |
205 | (@pxref{Creating Strings}), but it additionally removes quoting from | |
206 | the substrings. It then makes a list of the substrings and returns | |
207 | it. | |
208 | ||
209 | If @var{separators} is omitted or nil, it defaults to @code{"\\s-+"}, | |
210 | which is a regular expression that matches one or more characters with | |
211 | whitespace syntax (@pxref{Syntax Class Table}). | |
212 | ||
213 | The quoting this function supports is of 2 styles: by enclosing a | |
214 | whole string in double quotes @code{"@dots{}"}, or by quoting | |
215 | individual characters with a backslash escape @samp{\}. The latter is | |
216 | also used in Lisp strings, so this function can handle those as well. | |
217 | @end defun | |
218 | ||
219 | @defun combine-and-quote-strings list-of-strings &optional separator | |
220 | This function concatenates @var{list-of-strings} into a single string, | |
221 | quoting each string in the list that needs quoting as it goes. It | |
222 | also sticks the @var{separator} string in between each pair of strings | |
223 | in the result, and returns that result. If @var{separator} is omitted | |
224 | or @code{nil}, it defaults to a blank @code{" "}. | |
225 | ||
226 | The strings in @var{list-of-strings} that need quoting are those that | |
227 | include @var{separator} as their substring. Quoting a string encloses | |
228 | it in double quotes @code{"@dots{}"}. In the simplest case, if you | |
229 | are consing a shell command from the individual command-line | |
230 | arguments, every argument that includes embedded blanks will be | |
231 | quoted. | |
232 | @end defun | |
233 | ||
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234 | @node Synchronous Processes |
235 | @section Creating a Synchronous Process | |
236 | @cindex synchronous subprocess | |
237 | ||
238 | After a @dfn{synchronous process} is created, Emacs waits for the | |
239 | process to terminate before continuing. Starting Dired on GNU or | |
240 | Unix@footnote{On other systems, Emacs uses a Lisp emulation of | |
241 | @code{ls}; see @ref{Contents of Directories}.} is an example of this: it | |
242 | runs @code{ls} in a synchronous process, then modifies the output | |
243 | slightly. Because the process is synchronous, the entire directory | |
244 | listing arrives in the buffer before Emacs tries to do anything with it. | |
245 | ||
246 | While Emacs waits for the synchronous subprocess to terminate, the | |
247 | user can quit by typing @kbd{C-g}. The first @kbd{C-g} tries to kill | |
248 | the subprocess with a @code{SIGINT} signal; but it waits until the | |
249 | subprocess actually terminates before quitting. If during that time the | |
250 | user types another @kbd{C-g}, that kills the subprocess instantly with | |
251 | @code{SIGKILL} and quits immediately (except on MS-DOS, where killing | |
252 | other processes doesn't work). @xref{Quitting}. | |
253 | ||
254 | The synchronous subprocess functions return an indication of how the | |
255 | process terminated. | |
256 | ||
257 | The output from a synchronous subprocess is generally decoded using a | |
258 | coding system, much like text read from a file. The input sent to a | |
259 | subprocess by @code{call-process-region} is encoded using a coding | |
260 | system, much like text written into a file. @xref{Coding Systems}. | |
261 | ||
262 | @defun call-process program &optional infile destination display &rest args | |
263 | This function calls @var{program} in a separate process and waits for | |
264 | it to finish. | |
265 | ||
266 | The standard input for the process comes from file @var{infile} if | |
267 | @var{infile} is not @code{nil}, and from the null device otherwise. | |
268 | The argument @var{destination} says where to put the process output. | |
269 | Here are the possibilities: | |
270 | ||
271 | @table @asis | |
272 | @item a buffer | |
273 | Insert the output in that buffer, before point. This includes both the | |
274 | standard output stream and the standard error stream of the process. | |
275 | ||
276 | @item a string | |
277 | Insert the output in a buffer with that name, before point. | |
278 | ||
279 | @item @code{t} | |
280 | Insert the output in the current buffer, before point. | |
281 | ||
282 | @item @code{nil} | |
283 | Discard the output. | |
284 | ||
285 | @item 0 | |
286 | Discard the output, and return @code{nil} immediately without waiting | |
287 | for the subprocess to finish. | |
288 | ||
289 | In this case, the process is not truly synchronous, since it can run in | |
290 | parallel with Emacs; but you can think of it as synchronous in that | |
291 | Emacs is essentially finished with the subprocess as soon as this | |
292 | function returns. | |
293 | ||
294 | MS-DOS doesn't support asynchronous subprocesses, so this option doesn't | |
295 | work there. | |
296 | ||
297 | @item @code{(@var{real-destination} @var{error-destination})} | |
298 | Keep the standard output stream separate from the standard error stream; | |
299 | deal with the ordinary output as specified by @var{real-destination}, | |
300 | and dispose of the error output according to @var{error-destination}. | |
301 | If @var{error-destination} is @code{nil}, that means to discard the | |
302 | error output, @code{t} means mix it with the ordinary output, and a | |
303 | string specifies a file name to redirect error output into. | |
304 | ||
305 | You can't directly specify a buffer to put the error output in; that is | |
306 | too difficult to implement. But you can achieve this result by sending | |
307 | the error output to a temporary file and then inserting the file into a | |
308 | buffer. | |
309 | @end table | |
310 | ||
311 | If @var{display} is non-@code{nil}, then @code{call-process} redisplays | |
312 | the buffer as output is inserted. (However, if the coding system chosen | |
313 | for decoding output is @code{undecided}, meaning deduce the encoding | |
314 | from the actual data, then redisplay sometimes cannot continue once | |
315 | non-@acronym{ASCII} characters are encountered. There are fundamental | |
316 | reasons why it is hard to fix this; see @ref{Output from Processes}.) | |
317 | ||
318 | Otherwise the function @code{call-process} does no redisplay, and the | |
319 | results become visible on the screen only when Emacs redisplays that | |
320 | buffer in the normal course of events. | |
321 | ||
322 | The remaining arguments, @var{args}, are strings that specify command | |
323 | line arguments for the program. | |
324 | ||
325 | The value returned by @code{call-process} (unless you told it not to | |
326 | wait) indicates the reason for process termination. A number gives the | |
327 | exit status of the subprocess; 0 means success, and any other value | |
328 | means failure. If the process terminated with a signal, | |
329 | @code{call-process} returns a string describing the signal. | |
330 | ||
331 | In the examples below, the buffer @samp{foo} is current. | |
332 | ||
333 | @smallexample | |
334 | @group | |
335 | (call-process "pwd" nil t) | |
336 | @result{} 0 | |
337 | ||
338 | ---------- Buffer: foo ---------- | |
339 | /usr/user/lewis/manual | |
340 | ---------- Buffer: foo ---------- | |
341 | @end group | |
342 | ||
343 | @group | |
344 | (call-process "grep" nil "bar" nil "lewis" "/etc/passwd") | |
345 | @result{} 0 | |
346 | ||
347 | ---------- Buffer: bar ---------- | |
348 | lewis:5LTsHm66CSWKg:398:21:Bil Lewis:/user/lewis:/bin/csh | |
349 | ||
350 | ---------- Buffer: bar ---------- | |
351 | @end group | |
352 | @end smallexample | |
353 | ||
354 | Here is a good example of the use of @code{call-process}, which used to | |
355 | be found in the definition of @code{insert-directory}: | |
356 | ||
357 | @smallexample | |
358 | @group | |
359 | (call-process insert-directory-program nil t nil @var{switches} | |
360 | (if full-directory-p | |
361 | (concat (file-name-as-directory file) ".") | |
362 | file)) | |
363 | @end group | |
364 | @end smallexample | |
365 | @end defun | |
366 | ||
367 | @defun process-file program &optional infile buffer display &rest args | |
368 | This function processes files synchronously in a separate process. It | |
369 | is similar to @code{call-process} but may invoke a file handler based | |
370 | on the value of the variable @code{default-directory}. The current | |
371 | working directory of the subprocess is @code{default-directory}. | |
372 | ||
373 | The arguments are handled in almost the same way as for | |
374 | @code{call-process}, with the following differences: | |
375 | ||
376 | Some file handlers may not support all combinations and forms of the | |
377 | arguments @var{infile}, @var{buffer}, and @var{display}. For example, | |
378 | some file handlers might behave as if @var{display} were @code{nil}, | |
379 | regardless of the value actually passed. As another example, some | |
380 | file handlers might not support separating standard output and error | |
381 | output by way of the @var{buffer} argument. | |
382 | ||
383 | If a file handler is invoked, it determines the program to run based | |
384 | on the first argument @var{program}. For instance, consider that a | |
385 | handler for remote files is invoked. Then the path that is used for | |
386 | searching the program might be different than @code{exec-path}. | |
387 | ||
388 | The second argument @var{infile} may invoke a file handler. The file | |
389 | handler could be different from the handler chosen for the | |
390 | @code{process-file} function itself. (For example, | |
391 | @code{default-directory} could be on a remote host, whereas | |
392 | @var{infile} is on another remote host. Or @code{default-directory} | |
393 | could be non-special, whereas @var{infile} is on a remote host.) | |
394 | ||
395 | If @var{buffer} is a list of the form @code{(@var{real-destination} | |
396 | @var{error-destination})}, and @var{error-destination} names a file, | |
397 | then the same remarks as for @var{infile} apply. | |
398 | ||
399 | The remaining arguments (@var{args}) will be passed to the process | |
400 | verbatim. Emacs is not involved in processing file names that are | |
401 | present in @var{args}. To avoid confusion, it may be best to avoid | |
402 | absolute file names in @var{args}, but rather to specify all file | |
403 | names as relative to @code{default-directory}. The function | |
404 | @code{file-relative-name} is useful for constructing such relative | |
405 | file names. | |
406 | @end defun | |
407 | ||
408 | @defun call-process-region start end program &optional delete destination display &rest args | |
409 | This function sends the text from @var{start} to @var{end} as | |
410 | standard input to a process running @var{program}. It deletes the text | |
411 | sent if @var{delete} is non-@code{nil}; this is useful when | |
412 | @var{destination} is @code{t}, to insert the output in the current | |
413 | buffer in place of the input. | |
414 | ||
415 | The arguments @var{destination} and @var{display} control what to do | |
416 | with the output from the subprocess, and whether to update the display | |
417 | as it comes in. For details, see the description of | |
418 | @code{call-process}, above. If @var{destination} is the integer 0, | |
419 | @code{call-process-region} discards the output and returns @code{nil} | |
420 | immediately, without waiting for the subprocess to finish (this only | |
421 | works if asynchronous subprocesses are supported). | |
422 | ||
423 | The remaining arguments, @var{args}, are strings that specify command | |
424 | line arguments for the program. | |
425 | ||
426 | The return value of @code{call-process-region} is just like that of | |
427 | @code{call-process}: @code{nil} if you told it to return without | |
428 | waiting; otherwise, a number or string which indicates how the | |
429 | subprocess terminated. | |
430 | ||
431 | In the following example, we use @code{call-process-region} to run the | |
432 | @code{cat} utility, with standard input being the first five characters | |
433 | in buffer @samp{foo} (the word @samp{input}). @code{cat} copies its | |
434 | standard input into its standard output. Since the argument | |
435 | @var{destination} is @code{t}, this output is inserted in the current | |
436 | buffer. | |
437 | ||
438 | @smallexample | |
439 | @group | |
440 | ---------- Buffer: foo ---------- | |
441 | input@point{} | |
442 | ---------- Buffer: foo ---------- | |
443 | @end group | |
444 | ||
445 | @group | |
446 | (call-process-region 1 6 "cat" nil t) | |
447 | @result{} 0 | |
448 | ||
449 | ---------- Buffer: foo ---------- | |
450 | inputinput@point{} | |
451 | ---------- Buffer: foo ---------- | |
452 | @end group | |
453 | @end smallexample | |
454 | ||
455 | The @code{shell-command-on-region} command uses | |
456 | @code{call-process-region} like this: | |
457 | ||
458 | @smallexample | |
459 | @group | |
460 | (call-process-region | |
461 | start end | |
462 | shell-file-name ; @r{Name of program.} | |
463 | nil ; @r{Do not delete region.} | |
464 | buffer ; @r{Send output to @code{buffer}.} | |
465 | nil ; @r{No redisplay during output.} | |
466 | "-c" command) ; @r{Arguments for the shell.} | |
467 | @end group | |
468 | @end smallexample | |
469 | @end defun | |
470 | ||
471 | @defun call-process-shell-command command &optional infile destination display &rest args | |
472 | This function executes the shell command @var{command} synchronously | |
473 | in a separate process. The final arguments @var{args} are additional | |
474 | arguments to add at the end of @var{command}. The other arguments | |
475 | are handled as in @code{call-process}. | |
476 | @end defun | |
477 | ||
478 | @defun process-file-shell-command command &optional infile destination display &rest args | |
479 | This function is like @code{call-process-shell-command}, but uses | |
480 | @code{process-file} internally. Depending on @code{default-directory}, | |
481 | @var{command} can be executed also on remote hosts. | |
482 | @end defun | |
483 | ||
484 | @defun shell-command-to-string command | |
485 | This function executes @var{command} (a string) as a shell command, | |
486 | then returns the command's output as a string. | |
487 | @end defun | |
488 | ||
583d8b3c EZ |
489 | @defun process-lines program &rest args |
490 | This function runs @var{program} in a separate process, waits for it | |
491 | to finish, and returns its output as a list of strings. Each string | |
492 | in the list holds a single line of text output by the program; the | |
493 | end-of-line characters are stripped from each line. The arguments | |
494 | beyond @var{program}, @var{args}, are strings that specify | |
495 | command-line arguments with which to run the program. | |
496 | ||
497 | If @var{program} exits with a non-zero exit status, this function | |
498 | signals an error. | |
499 | ||
500 | This function works by calling @code{call-process}, so program output | |
501 | is decoded in the same way as for @code{call-process}. | |
502 | @end defun | |
503 | ||
b8d4c8d0 GM |
504 | @node Asynchronous Processes |
505 | @section Creating an Asynchronous Process | |
506 | @cindex asynchronous subprocess | |
507 | ||
508 | After an @dfn{asynchronous process} is created, Emacs and the subprocess | |
509 | both continue running immediately. The process thereafter runs | |
510 | in parallel with Emacs, and the two can communicate with each other | |
511 | using the functions described in the following sections. However, | |
512 | communication is only partially asynchronous: Emacs sends data to the | |
513 | process only when certain functions are called, and Emacs accepts data | |
514 | from the process only when Emacs is waiting for input or for a time | |
515 | delay. | |
516 | ||
517 | Here we describe how to create an asynchronous process. | |
518 | ||
519 | @defun start-process name buffer-or-name program &rest args | |
520 | This function creates a new asynchronous subprocess and starts the | |
521 | program @var{program} running in it. It returns a process object that | |
522 | stands for the new subprocess in Lisp. The argument @var{name} | |
523 | specifies the name for the process object; if a process with this name | |
524 | already exists, then @var{name} is modified (by appending @samp{<1>}, | |
525 | etc.) to be unique. The buffer @var{buffer-or-name} is the buffer to | |
526 | associate with the process. | |
527 | ||
528 | The remaining arguments, @var{args}, are strings that specify command | |
529 | line arguments for the program. | |
530 | ||
531 | In the example below, the first process is started and runs (rather, | |
532 | sleeps) for 100 seconds. Meanwhile, the second process is started, and | |
533 | given the name @samp{my-process<1>} for the sake of uniqueness. It | |
534 | inserts the directory listing at the end of the buffer @samp{foo}, | |
535 | before the first process finishes. Then it finishes, and a message to | |
536 | that effect is inserted in the buffer. Much later, the first process | |
537 | finishes, and another message is inserted in the buffer for it. | |
538 | ||
539 | @smallexample | |
540 | @group | |
541 | (start-process "my-process" "foo" "sleep" "100") | |
542 | @result{} #<process my-process> | |
543 | @end group | |
544 | ||
545 | @group | |
546 | (start-process "my-process" "foo" "ls" "-l" "/user/lewis/bin") | |
547 | @result{} #<process my-process<1>> | |
548 | ||
549 | ---------- Buffer: foo ---------- | |
550 | total 2 | |
551 | lrwxrwxrwx 1 lewis 14 Jul 22 10:12 gnuemacs --> /emacs | |
552 | -rwxrwxrwx 1 lewis 19 Jul 30 21:02 lemon | |
553 | ||
554 | Process my-process<1> finished | |
555 | ||
556 | Process my-process finished | |
557 | ---------- Buffer: foo ---------- | |
558 | @end group | |
559 | @end smallexample | |
560 | @end defun | |
561 | ||
562 | @defun start-file-process name buffer-or-name program &rest args | |
563 | Like @code{start-process}, this function starts a new asynchronous | |
564 | subprocess running @var{program} in it, and returns its process | |
565 | object---when @code{default-directory} is not a magic file name. | |
566 | ||
567 | If @code{default-directory} is magic, the function invokes its file | |
568 | handler instead. This handler ought to run @var{program}, perhaps on | |
569 | the local host, perhaps on a remote host that corresponds to | |
570 | @code{default-directory}. In the latter case, the local part of | |
571 | @code{default-directory} becomes the working directory of the process. | |
572 | ||
573 | This function does not try to invoke file name handlers for | |
574 | @var{program} or for the @var{program-args}. | |
575 | ||
576 | Depending on the implementation of the file handler, it might not be | |
577 | possible to apply @code{process-filter} or @code{process-sentinel} to | |
578 | the resulting process object (@pxref{Filter Functions}, @pxref{Sentinels}). | |
579 | ||
580 | Some file handlers may not support @code{start-file-process} (for | |
581 | example @code{ange-ftp-hook-function}). In such cases, the function | |
582 | does nothing and returns @code{nil}. | |
583 | @end defun | |
584 | ||
585 | @defun start-process-shell-command name buffer-or-name command &rest command-args | |
586 | This function is like @code{start-process} except that it uses a shell | |
587 | to execute the specified command. The argument @var{command} is a shell | |
588 | command name, and @var{command-args} are the arguments for the shell | |
589 | command. The variable @code{shell-file-name} specifies which shell to | |
590 | use. | |
591 | ||
592 | The point of running a program through the shell, rather than directly | |
593 | with @code{start-process}, is so that you can employ shell features such | |
594 | as wildcards in the arguments. It follows that if you include an | |
595 | arbitrary user-specified arguments in the command, you should quote it | |
596 | with @code{shell-quote-argument} first, so that any special shell | |
597 | characters do @emph{not} have their special shell meanings. @xref{Shell | |
598 | Arguments}. | |
599 | @end defun | |
600 | ||
601 | @defun start-file-process-shell-command name buffer-or-name command &rest command-args | |
602 | This function is like @code{start-process-shell-command}, but uses | |
603 | @code{start-file-process} internally. By this, @var{command} can be | |
604 | executed also on remote hosts, depending on @code{default-directory}. | |
605 | @end defun | |
606 | ||
607 | @defvar process-connection-type | |
608 | @cindex pipes | |
609 | @cindex @acronym{PTY}s | |
610 | This variable controls the type of device used to communicate with | |
611 | asynchronous subprocesses. If it is non-@code{nil}, then @acronym{PTY}s are | |
612 | used, when available. Otherwise, pipes are used. | |
613 | ||
614 | @acronym{PTY}s are usually preferable for processes visible to the user, as | |
615 | in Shell mode, because they allow job control (@kbd{C-c}, @kbd{C-z}, | |
616 | etc.) to work between the process and its children, whereas pipes do | |
617 | not. For subprocesses used for internal purposes by programs, it is | |
618 | often better to use a pipe, because they are more efficient. In | |
619 | addition, the total number of @acronym{PTY}s is limited on many systems and | |
620 | it is good not to waste them. | |
621 | ||
622 | The value of @code{process-connection-type} takes effect when | |
623 | @code{start-process} is called. So you can specify how to communicate | |
624 | with one subprocess by binding the variable around the call to | |
625 | @code{start-process}. | |
626 | ||
627 | @smallexample | |
628 | @group | |
629 | (let ((process-connection-type nil)) ; @r{Use a pipe.} | |
630 | (start-process @dots{})) | |
631 | @end group | |
632 | @end smallexample | |
633 | ||
634 | To determine whether a given subprocess actually got a pipe or a | |
635 | @acronym{PTY}, use the function @code{process-tty-name} (@pxref{Process | |
636 | Information}). | |
637 | @end defvar | |
638 | ||
639 | @node Deleting Processes | |
640 | @section Deleting Processes | |
641 | @cindex deleting processes | |
642 | ||
643 | @dfn{Deleting a process} disconnects Emacs immediately from the | |
644 | subprocess. Processes are deleted automatically after they terminate, | |
645 | but not necessarily right away. You can delete a process explicitly | |
646 | at any time. If you delete a terminated process explicitly before it | |
647 | is deleted automatically, no harm results. Deleting a running | |
648 | process sends a signal to terminate it (and its child processes if | |
649 | any), and calls the process sentinel if it has one. @xref{Sentinels}. | |
650 | ||
651 | When a process is deleted, the process object itself continues to | |
652 | exist as long as other Lisp objects point to it. All the Lisp | |
653 | primitives that work on process objects accept deleted processes, but | |
654 | those that do I/O or send signals will report an error. The process | |
655 | mark continues to point to the same place as before, usually into a | |
656 | buffer where output from the process was being inserted. | |
657 | ||
658 | @defopt delete-exited-processes | |
659 | This variable controls automatic deletion of processes that have | |
660 | terminated (due to calling @code{exit} or to a signal). If it is | |
661 | @code{nil}, then they continue to exist until the user runs | |
662 | @code{list-processes}. Otherwise, they are deleted immediately after | |
663 | they exit. | |
664 | @end defopt | |
665 | ||
666 | @defun delete-process process | |
667 | This function deletes a process, killing it with a @code{SIGKILL} | |
668 | signal. The argument may be a process, the name of a process, a | |
669 | buffer, or the name of a buffer. (A buffer or buffer-name stands for | |
670 | the process that @code{get-buffer-process} returns.) Calling | |
671 | @code{delete-process} on a running process terminates it, updates the | |
672 | process status, and runs the sentinel (if any) immediately. If the | |
673 | process has already terminated, calling @code{delete-process} has no | |
674 | effect on its status, or on the running of its sentinel (which will | |
675 | happen sooner or later). | |
676 | ||
677 | @smallexample | |
678 | @group | |
679 | (delete-process "*shell*") | |
680 | @result{} nil | |
681 | @end group | |
682 | @end smallexample | |
683 | @end defun | |
684 | ||
685 | @node Process Information | |
686 | @section Process Information | |
687 | ||
688 | Several functions return information about processes. | |
689 | @code{list-processes} is provided for interactive use. | |
690 | ||
691 | @deffn Command list-processes &optional query-only | |
692 | This command displays a listing of all living processes. In addition, | |
693 | it finally deletes any process whose status was @samp{Exited} or | |
694 | @samp{Signaled}. It returns @code{nil}. | |
695 | ||
696 | If @var{query-only} is non-@code{nil} then it lists only processes | |
697 | whose query flag is non-@code{nil}. @xref{Query Before Exit}. | |
698 | @end deffn | |
699 | ||
700 | @defun process-list | |
701 | This function returns a list of all processes that have not been deleted. | |
702 | ||
703 | @smallexample | |
704 | @group | |
705 | (process-list) | |
706 | @result{} (#<process display-time> #<process shell>) | |
707 | @end group | |
708 | @end smallexample | |
709 | @end defun | |
710 | ||
711 | @defun get-process name | |
712 | This function returns the process named @var{name}, or @code{nil} if | |
713 | there is none. An error is signaled if @var{name} is not a string. | |
714 | ||
715 | @smallexample | |
716 | @group | |
717 | (get-process "shell") | |
718 | @result{} #<process shell> | |
719 | @end group | |
720 | @end smallexample | |
721 | @end defun | |
722 | ||
723 | @defun process-command process | |
724 | This function returns the command that was executed to start | |
725 | @var{process}. This is a list of strings, the first string being the | |
726 | program executed and the rest of the strings being the arguments that | |
727 | were given to the program. | |
728 | ||
729 | @smallexample | |
730 | @group | |
731 | (process-command (get-process "shell")) | |
732 | @result{} ("/bin/csh" "-i") | |
733 | @end group | |
734 | @end smallexample | |
735 | @end defun | |
736 | ||
c73e02fa GM |
737 | @defun process-contact process &optional key |
738 | ||
739 | This function returns information about how a network or serial | |
740 | process was set up. For a network process, when @var{key} is | |
741 | @code{nil}, it returns @code{(@var{hostname} @var{service})} which | |
742 | specifies what you connected to. For a serial process, when @var{key} | |
743 | is @code{nil}, it returns @code{(@var{port} @var{speed})}. For an | |
744 | ordinary child process, this function always returns @code{t}. | |
745 | ||
746 | If @var{key} is @code{t}, the value is the complete status information | |
747 | for the connection, server, or serial port; that is, the list of | |
748 | keywords and values specified in @code{make-network-process} or | |
749 | @code{make-serial-process}, except that some of the values represent | |
750 | the current status instead of what you specified. | |
751 | ||
752 | For a network process: | |
753 | ||
754 | @table @code | |
755 | @item :buffer | |
756 | The associated value is the process buffer. | |
757 | @item :filter | |
758 | The associated value is the process filter function. | |
759 | @item :sentinel | |
760 | The associated value is the process sentinel function. | |
761 | @item :remote | |
762 | In a connection, the address in internal format of the remote peer. | |
763 | @item :local | |
764 | The local address, in internal format. | |
765 | @item :service | |
766 | In a server, if you specified @code{t} for @var{service}, | |
767 | this value is the actual port number. | |
768 | @end table | |
769 | ||
770 | @code{:local} and @code{:remote} are included even if they were not | |
771 | specified explicitly in @code{make-network-process}. | |
772 | ||
773 | For a serial process, see @code{make-serial-process} and | |
774 | @code{serial-process-configure} for a list of keys. | |
775 | ||
776 | If @var{key} is a keyword, the function returns the value corresponding | |
777 | to that keyword. | |
778 | @end defun | |
779 | ||
b8d4c8d0 GM |
780 | @defun process-id process |
781 | This function returns the @acronym{PID} of @var{process}. This is an | |
782 | integer that distinguishes the process @var{process} from all other | |
783 | processes running on the same computer at the current time. The | |
784 | @acronym{PID} of a process is chosen by the operating system kernel when the | |
785 | process is started and remains constant as long as the process exists. | |
786 | @end defun | |
787 | ||
788 | @defun process-name process | |
789 | This function returns the name of @var{process}. | |
790 | @end defun | |
791 | ||
792 | @defun process-status process-name | |
793 | This function returns the status of @var{process-name} as a symbol. | |
794 | The argument @var{process-name} must be a process, a buffer, a | |
795 | process name (string) or a buffer name (string). | |
796 | ||
797 | The possible values for an actual subprocess are: | |
798 | ||
799 | @table @code | |
800 | @item run | |
801 | for a process that is running. | |
802 | @item stop | |
803 | for a process that is stopped but continuable. | |
804 | @item exit | |
805 | for a process that has exited. | |
806 | @item signal | |
807 | for a process that has received a fatal signal. | |
808 | @item open | |
809 | for a network connection that is open. | |
810 | @item closed | |
811 | for a network connection that is closed. Once a connection | |
812 | is closed, you cannot reopen it, though you might be able to open | |
813 | a new connection to the same place. | |
814 | @item connect | |
815 | for a non-blocking connection that is waiting to complete. | |
816 | @item failed | |
817 | for a non-blocking connection that has failed to complete. | |
818 | @item listen | |
819 | for a network server that is listening. | |
820 | @item nil | |
821 | if @var{process-name} is not the name of an existing process. | |
822 | @end table | |
823 | ||
824 | @smallexample | |
825 | @group | |
826 | (process-status "shell") | |
827 | @result{} run | |
828 | @end group | |
829 | @group | |
830 | (process-status (get-buffer "*shell*")) | |
831 | @result{} run | |
832 | @end group | |
833 | @group | |
834 | x | |
835 | @result{} #<process xx<1>> | |
836 | (process-status x) | |
837 | @result{} exit | |
838 | @end group | |
839 | @end smallexample | |
840 | ||
841 | For a network connection, @code{process-status} returns one of the symbols | |
842 | @code{open} or @code{closed}. The latter means that the other side | |
843 | closed the connection, or Emacs did @code{delete-process}. | |
844 | @end defun | |
845 | ||
c73e02fa GM |
846 | @defun process-type process |
847 | This function returns the symbol @code{network} for a network | |
848 | connection or server, @code{serial} for a serial port connection, or | |
849 | @code{real} for a real subprocess. | |
850 | @end defun | |
851 | ||
b8d4c8d0 GM |
852 | @defun process-exit-status process |
853 | This function returns the exit status of @var{process} or the signal | |
854 | number that killed it. (Use the result of @code{process-status} to | |
855 | determine which of those it is.) If @var{process} has not yet | |
856 | terminated, the value is 0. | |
857 | @end defun | |
858 | ||
859 | @defun process-tty-name process | |
860 | This function returns the terminal name that @var{process} is using for | |
861 | its communication with Emacs---or @code{nil} if it is using pipes | |
862 | instead of a terminal (see @code{process-connection-type} in | |
863 | @ref{Asynchronous Processes}). | |
864 | @end defun | |
865 | ||
866 | @defun process-coding-system process | |
867 | @anchor{Coding systems for a subprocess} | |
868 | This function returns a cons cell describing the coding systems in use | |
869 | for decoding output from @var{process} and for encoding input to | |
870 | @var{process} (@pxref{Coding Systems}). The value has this form: | |
871 | ||
872 | @example | |
873 | (@var{coding-system-for-decoding} . @var{coding-system-for-encoding}) | |
874 | @end example | |
875 | @end defun | |
876 | ||
877 | @defun set-process-coding-system process &optional decoding-system encoding-system | |
878 | This function specifies the coding systems to use for subsequent output | |
879 | from and input to @var{process}. It will use @var{decoding-system} to | |
880 | decode subprocess output, and @var{encoding-system} to encode subprocess | |
881 | input. | |
882 | @end defun | |
883 | ||
884 | Every process also has a property list that you can use to store | |
885 | miscellaneous values associated with the process. | |
886 | ||
887 | @defun process-get process propname | |
888 | This function returns the value of the @var{propname} property | |
889 | of @var{process}. | |
890 | @end defun | |
891 | ||
892 | @defun process-put process propname value | |
893 | This function sets the value of the @var{propname} property | |
894 | of @var{process} to @var{value}. | |
895 | @end defun | |
896 | ||
897 | @defun process-plist process | |
898 | This function returns the process plist of @var{process}. | |
899 | @end defun | |
900 | ||
901 | @defun set-process-plist process plist | |
902 | This function sets the process plist of @var{process} to @var{plist}. | |
903 | @end defun | |
904 | ||
905 | @node Input to Processes | |
906 | @section Sending Input to Processes | |
907 | @cindex process input | |
908 | ||
909 | Asynchronous subprocesses receive input when it is sent to them by | |
910 | Emacs, which is done with the functions in this section. You must | |
911 | specify the process to send input to, and the input data to send. The | |
912 | data appears on the ``standard input'' of the subprocess. | |
913 | ||
914 | Some operating systems have limited space for buffered input in a | |
915 | @acronym{PTY}. On these systems, Emacs sends an @acronym{EOF} | |
916 | periodically amidst the other characters, to force them through. For | |
917 | most programs, these @acronym{EOF}s do no harm. | |
918 | ||
919 | Subprocess input is normally encoded using a coding system before the | |
920 | subprocess receives it, much like text written into a file. You can use | |
921 | @code{set-process-coding-system} to specify which coding system to use | |
922 | (@pxref{Process Information}). Otherwise, the coding system comes from | |
923 | @code{coding-system-for-write}, if that is non-@code{nil}; or else from | |
924 | the defaulting mechanism (@pxref{Default Coding Systems}). | |
925 | ||
926 | Sometimes the system is unable to accept input for that process, | |
927 | because the input buffer is full. When this happens, the send functions | |
928 | wait a short while, accepting output from subprocesses, and then try | |
929 | again. This gives the subprocess a chance to read more of its pending | |
930 | input and make space in the buffer. It also allows filters, sentinels | |
931 | and timers to run---so take account of that in writing your code. | |
932 | ||
933 | In these functions, the @var{process} argument can be a process or | |
934 | the name of a process, or a buffer or buffer name (which stands | |
935 | for a process via @code{get-buffer-process}). @code{nil} means | |
936 | the current buffer's process. | |
937 | ||
938 | @defun process-send-string process string | |
939 | This function sends @var{process} the contents of @var{string} as | |
940 | standard input. If it is @code{nil}, the current buffer's process is used. | |
941 | ||
942 | The function returns @code{nil}. | |
943 | ||
944 | @smallexample | |
945 | @group | |
946 | (process-send-string "shell<1>" "ls\n") | |
947 | @result{} nil | |
948 | @end group | |
949 | ||
950 | ||
951 | @group | |
952 | ---------- Buffer: *shell* ---------- | |
953 | ... | |
954 | introduction.texi syntax-tables.texi~ | |
955 | introduction.texi~ text.texi | |
956 | introduction.txt text.texi~ | |
957 | ... | |
958 | ---------- Buffer: *shell* ---------- | |
959 | @end group | |
960 | @end smallexample | |
961 | @end defun | |
962 | ||
963 | @defun process-send-region process start end | |
964 | This function sends the text in the region defined by @var{start} and | |
965 | @var{end} as standard input to @var{process}. | |
966 | ||
967 | An error is signaled unless both @var{start} and @var{end} are | |
968 | integers or markers that indicate positions in the current buffer. (It | |
969 | is unimportant which number is larger.) | |
970 | @end defun | |
971 | ||
972 | @defun process-send-eof &optional process | |
973 | This function makes @var{process} see an end-of-file in its | |
974 | input. The @acronym{EOF} comes after any text already sent to it. | |
975 | ||
976 | The function returns @var{process}. | |
977 | ||
978 | @smallexample | |
979 | @group | |
980 | (process-send-eof "shell") | |
981 | @result{} "shell" | |
982 | @end group | |
983 | @end smallexample | |
984 | @end defun | |
985 | ||
986 | @defun process-running-child-p process | |
987 | This function will tell you whether a subprocess has given control of | |
988 | its terminal to its own child process. The value is @code{t} if this is | |
989 | true, or if Emacs cannot tell; it is @code{nil} if Emacs can be certain | |
990 | that this is not so. | |
991 | @end defun | |
992 | ||
993 | @node Signals to Processes | |
994 | @section Sending Signals to Processes | |
995 | @cindex process signals | |
996 | @cindex sending signals | |
997 | @cindex signals | |
998 | ||
999 | @dfn{Sending a signal} to a subprocess is a way of interrupting its | |
1000 | activities. There are several different signals, each with its own | |
1001 | meaning. The set of signals and their names is defined by the operating | |
1002 | system. For example, the signal @code{SIGINT} means that the user has | |
1003 | typed @kbd{C-c}, or that some analogous thing has happened. | |
1004 | ||
1005 | Each signal has a standard effect on the subprocess. Most signals | |
1006 | kill the subprocess, but some stop or resume execution instead. Most | |
1007 | signals can optionally be handled by programs; if the program handles | |
1008 | the signal, then we can say nothing in general about its effects. | |
1009 | ||
1010 | You can send signals explicitly by calling the functions in this | |
1011 | section. Emacs also sends signals automatically at certain times: | |
1012 | killing a buffer sends a @code{SIGHUP} signal to all its associated | |
1013 | processes; killing Emacs sends a @code{SIGHUP} signal to all remaining | |
1014 | processes. (@code{SIGHUP} is a signal that usually indicates that the | |
1015 | user hung up the phone.) | |
1016 | ||
1017 | Each of the signal-sending functions takes two optional arguments: | |
1018 | @var{process} and @var{current-group}. | |
1019 | ||
1020 | The argument @var{process} must be either a process, a process | |
1021 | name, a buffer, a buffer name, or @code{nil}. A buffer or buffer name | |
1022 | stands for a process through @code{get-buffer-process}. @code{nil} | |
1023 | stands for the process associated with the current buffer. An error | |
1024 | is signaled if @var{process} does not identify a process. | |
1025 | ||
1026 | The argument @var{current-group} is a flag that makes a difference | |
1027 | when you are running a job-control shell as an Emacs subprocess. If it | |
1028 | is non-@code{nil}, then the signal is sent to the current process-group | |
1029 | of the terminal that Emacs uses to communicate with the subprocess. If | |
1030 | the process is a job-control shell, this means the shell's current | |
1031 | subjob. If it is @code{nil}, the signal is sent to the process group of | |
1032 | the immediate subprocess of Emacs. If the subprocess is a job-control | |
1033 | shell, this is the shell itself. | |
1034 | ||
1035 | The flag @var{current-group} has no effect when a pipe is used to | |
1036 | communicate with the subprocess, because the operating system does not | |
1037 | support the distinction in the case of pipes. For the same reason, | |
1038 | job-control shells won't work when a pipe is used. See | |
1039 | @code{process-connection-type} in @ref{Asynchronous Processes}. | |
1040 | ||
1041 | @defun interrupt-process &optional process current-group | |
1042 | This function interrupts the process @var{process} by sending the | |
1043 | signal @code{SIGINT}. Outside of Emacs, typing the ``interrupt | |
1044 | character'' (normally @kbd{C-c} on some systems, and @code{DEL} on | |
1045 | others) sends this signal. When the argument @var{current-group} is | |
1046 | non-@code{nil}, you can think of this function as ``typing @kbd{C-c}'' | |
1047 | on the terminal by which Emacs talks to the subprocess. | |
1048 | @end defun | |
1049 | ||
1050 | @defun kill-process &optional process current-group | |
1051 | This function kills the process @var{process} by sending the | |
1052 | signal @code{SIGKILL}. This signal kills the subprocess immediately, | |
1053 | and cannot be handled by the subprocess. | |
1054 | @end defun | |
1055 | ||
1056 | @defun quit-process &optional process current-group | |
1057 | This function sends the signal @code{SIGQUIT} to the process | |
1058 | @var{process}. This signal is the one sent by the ``quit | |
1059 | character'' (usually @kbd{C-b} or @kbd{C-\}) when you are not inside | |
1060 | Emacs. | |
1061 | @end defun | |
1062 | ||
1063 | @defun stop-process &optional process current-group | |
1064 | This function stops the process @var{process} by sending the | |
1065 | signal @code{SIGTSTP}. Use @code{continue-process} to resume its | |
1066 | execution. | |
1067 | ||
1068 | Outside of Emacs, on systems with job control, the ``stop character'' | |
1069 | (usually @kbd{C-z}) normally sends this signal. When | |
1070 | @var{current-group} is non-@code{nil}, you can think of this function as | |
1071 | ``typing @kbd{C-z}'' on the terminal Emacs uses to communicate with the | |
1072 | subprocess. | |
1073 | @end defun | |
1074 | ||
1075 | @defun continue-process &optional process current-group | |
1076 | This function resumes execution of the process @var{process} by sending | |
1077 | it the signal @code{SIGCONT}. This presumes that @var{process} was | |
1078 | stopped previously. | |
1079 | @end defun | |
1080 | ||
1081 | @c Emacs 19 feature | |
1082 | @defun signal-process process signal | |
1083 | This function sends a signal to process @var{process}. The argument | |
1084 | @var{signal} specifies which signal to send; it should be an integer. | |
1085 | ||
1086 | The @var{process} argument can be a system process @acronym{ID}; that | |
1087 | allows you to send signals to processes that are not children of | |
23dd4ecd | 1088 | Emacs. @xref{System Processes}. |
b8d4c8d0 GM |
1089 | @end defun |
1090 | ||
1091 | @node Output from Processes | |
1092 | @section Receiving Output from Processes | |
1093 | @cindex process output | |
1094 | @cindex output from processes | |
1095 | ||
1096 | There are two ways to receive the output that a subprocess writes to | |
1097 | its standard output stream. The output can be inserted in a buffer, | |
1098 | which is called the associated buffer of the process, or a function | |
1099 | called the @dfn{filter function} can be called to act on the output. If | |
1100 | the process has no buffer and no filter function, its output is | |
1101 | discarded. | |
1102 | ||
1103 | When a subprocess terminates, Emacs reads any pending output, | |
1104 | then stops reading output from that subprocess. Therefore, if the | |
1105 | subprocess has children that are still live and still producing | |
1106 | output, Emacs won't receive that output. | |
1107 | ||
1108 | Output from a subprocess can arrive only while Emacs is waiting: when | |
1109 | reading terminal input, in @code{sit-for} and @code{sleep-for} | |
1110 | (@pxref{Waiting}), and in @code{accept-process-output} (@pxref{Accepting | |
1111 | Output}). This minimizes the problem of timing errors that usually | |
1112 | plague parallel programming. For example, you can safely create a | |
1113 | process and only then specify its buffer or filter function; no output | |
1114 | can arrive before you finish, if the code in between does not call any | |
1115 | primitive that waits. | |
1116 | ||
1117 | @defvar process-adaptive-read-buffering | |
1118 | On some systems, when Emacs reads the output from a subprocess, the | |
1119 | output data is read in very small blocks, potentially resulting in | |
1120 | very poor performance. This behavior can be remedied to some extent | |
1121 | by setting the variable @var{process-adaptive-read-buffering} to a | |
1122 | non-@code{nil} value (the default), as it will automatically delay reading | |
1123 | from such processes, thus allowing them to produce more output before | |
1124 | Emacs tries to read it. | |
1125 | @end defvar | |
1126 | ||
1127 | It is impossible to separate the standard output and standard error | |
1128 | streams of the subprocess, because Emacs normally spawns the subprocess | |
1129 | inside a pseudo-TTY, and a pseudo-TTY has only one output channel. If | |
1130 | you want to keep the output to those streams separate, you should | |
1131 | redirect one of them to a file---for example, by using an appropriate | |
1132 | shell command. | |
1133 | ||
1134 | @menu | |
1135 | * Process Buffers:: If no filter, output is put in a buffer. | |
1136 | * Filter Functions:: Filter functions accept output from the process. | |
1137 | * Decoding Output:: Filters can get unibyte or multibyte strings. | |
1138 | * Accepting Output:: How to wait until process output arrives. | |
1139 | @end menu | |
1140 | ||
1141 | @node Process Buffers | |
1142 | @subsection Process Buffers | |
1143 | ||
1144 | A process can (and usually does) have an @dfn{associated buffer}, | |
1145 | which is an ordinary Emacs buffer that is used for two purposes: storing | |
1146 | the output from the process, and deciding when to kill the process. You | |
1147 | can also use the buffer to identify a process to operate on, since in | |
1148 | normal practice only one process is associated with any given buffer. | |
1149 | Many applications of processes also use the buffer for editing input to | |
1150 | be sent to the process, but this is not built into Emacs Lisp. | |
1151 | ||
1152 | Unless the process has a filter function (@pxref{Filter Functions}), | |
1153 | its output is inserted in the associated buffer. The position to insert | |
1154 | the output is determined by the @code{process-mark}, which is then | |
1155 | updated to point to the end of the text just inserted. Usually, but not | |
1156 | always, the @code{process-mark} is at the end of the buffer. | |
1157 | ||
1158 | @defun process-buffer process | |
1159 | This function returns the associated buffer of the process | |
1160 | @var{process}. | |
1161 | ||
1162 | @smallexample | |
1163 | @group | |
1164 | (process-buffer (get-process "shell")) | |
1165 | @result{} #<buffer *shell*> | |
1166 | @end group | |
1167 | @end smallexample | |
1168 | @end defun | |
1169 | ||
1170 | @defun process-mark process | |
1171 | This function returns the process marker for @var{process}, which is the | |
1172 | marker that says where to insert output from the process. | |
1173 | ||
1174 | If @var{process} does not have a buffer, @code{process-mark} returns a | |
1175 | marker that points nowhere. | |
1176 | ||
1177 | Insertion of process output in a buffer uses this marker to decide where | |
1178 | to insert, and updates it to point after the inserted text. That is why | |
1179 | successive batches of output are inserted consecutively. | |
1180 | ||
1181 | Filter functions normally should use this marker in the same fashion | |
1182 | as is done by direct insertion of output in the buffer. A good | |
1183 | example of a filter function that uses @code{process-mark} is found at | |
1184 | the end of the following section. | |
1185 | ||
1186 | When the user is expected to enter input in the process buffer for | |
1187 | transmission to the process, the process marker separates the new input | |
1188 | from previous output. | |
1189 | @end defun | |
1190 | ||
1191 | @defun set-process-buffer process buffer | |
1192 | This function sets the buffer associated with @var{process} to | |
1193 | @var{buffer}. If @var{buffer} is @code{nil}, the process becomes | |
1194 | associated with no buffer. | |
1195 | @end defun | |
1196 | ||
1197 | @defun get-buffer-process buffer-or-name | |
1198 | This function returns a nondeleted process associated with the buffer | |
1199 | specified by @var{buffer-or-name}. If there are several processes | |
1200 | associated with it, this function chooses one (currently, the one most | |
1201 | recently created, but don't count on that). Deletion of a process | |
1202 | (see @code{delete-process}) makes it ineligible for this function to | |
1203 | return. | |
1204 | ||
1205 | It is usually a bad idea to have more than one process associated with | |
1206 | the same buffer. | |
1207 | ||
1208 | @smallexample | |
1209 | @group | |
1210 | (get-buffer-process "*shell*") | |
1211 | @result{} #<process shell> | |
1212 | @end group | |
1213 | @end smallexample | |
1214 | ||
1215 | Killing the process's buffer deletes the process, which kills the | |
1216 | subprocess with a @code{SIGHUP} signal (@pxref{Signals to Processes}). | |
1217 | @end defun | |
1218 | ||
1219 | @node Filter Functions | |
1220 | @subsection Process Filter Functions | |
1221 | @cindex filter function | |
1222 | @cindex process filter | |
1223 | ||
1224 | A process @dfn{filter function} is a function that receives the | |
1225 | standard output from the associated process. If a process has a filter, | |
1226 | then @emph{all} output from that process is passed to the filter. The | |
1227 | process buffer is used directly for output from the process only when | |
1228 | there is no filter. | |
1229 | ||
1230 | The filter function can only be called when Emacs is waiting for | |
1231 | something, because process output arrives only at such times. Emacs | |
1232 | waits when reading terminal input, in @code{sit-for} and | |
1233 | @code{sleep-for} (@pxref{Waiting}), and in @code{accept-process-output} | |
1234 | (@pxref{Accepting Output}). | |
1235 | ||
1236 | A filter function must accept two arguments: the associated process | |
1237 | and a string, which is output just received from it. The function is | |
1238 | then free to do whatever it chooses with the output. | |
1239 | ||
1240 | Quitting is normally inhibited within a filter function---otherwise, | |
1241 | the effect of typing @kbd{C-g} at command level or to quit a user | |
1242 | command would be unpredictable. If you want to permit quitting inside | |
1243 | a filter function, bind @code{inhibit-quit} to @code{nil}. In most | |
1244 | cases, the right way to do this is with the macro | |
1245 | @code{with-local-quit}. @xref{Quitting}. | |
1246 | ||
1247 | If an error happens during execution of a filter function, it is | |
1248 | caught automatically, so that it doesn't stop the execution of whatever | |
1249 | program was running when the filter function was started. However, if | |
1250 | @code{debug-on-error} is non-@code{nil}, the error-catching is turned | |
1251 | off. This makes it possible to use the Lisp debugger to debug the | |
1252 | filter function. @xref{Debugger}. | |
1253 | ||
1254 | Many filter functions sometimes or always insert the text in the | |
1255 | process's buffer, mimicking the actions of Emacs when there is no | |
1256 | filter. Such filter functions need to use @code{set-buffer} in order to | |
1257 | be sure to insert in that buffer. To avoid setting the current buffer | |
1258 | semipermanently, these filter functions must save and restore the | |
1259 | current buffer. They should also update the process marker, and in some | |
1260 | cases update the value of point. Here is how to do these things: | |
1261 | ||
1262 | @smallexample | |
1263 | @group | |
1264 | (defun ordinary-insertion-filter (proc string) | |
1265 | (with-current-buffer (process-buffer proc) | |
1266 | (let ((moving (= (point) (process-mark proc)))) | |
1267 | @end group | |
1268 | @group | |
1269 | (save-excursion | |
1270 | ;; @r{Insert the text, advancing the process marker.} | |
1271 | (goto-char (process-mark proc)) | |
1272 | (insert string) | |
1273 | (set-marker (process-mark proc) (point))) | |
1274 | (if moving (goto-char (process-mark proc)))))) | |
1275 | @end group | |
1276 | @end smallexample | |
1277 | ||
1278 | @noindent | |
1279 | The reason to use @code{with-current-buffer}, rather than using | |
1280 | @code{save-excursion} to save and restore the current buffer, is so as | |
1281 | to preserve the change in point made by the second call to | |
1282 | @code{goto-char}. | |
1283 | ||
1284 | To make the filter force the process buffer to be visible whenever new | |
1285 | text arrives, insert the following line just before the | |
1286 | @code{with-current-buffer} construct: | |
1287 | ||
1288 | @smallexample | |
1289 | (display-buffer (process-buffer proc)) | |
1290 | @end smallexample | |
1291 | ||
1292 | To force point to the end of the new output, no matter where it was | |
1293 | previously, eliminate the variable @code{moving} and call | |
1294 | @code{goto-char} unconditionally. | |
1295 | ||
1296 | In earlier Emacs versions, every filter function that did regular | |
1297 | expression searching or matching had to explicitly save and restore the | |
1298 | match data. Now Emacs does this automatically for filter functions; | |
1299 | they never need to do it explicitly. @xref{Match Data}. | |
1300 | ||
1301 | A filter function that writes the output into the buffer of the | |
1302 | process should check whether the buffer is still alive. If it tries to | |
1303 | insert into a dead buffer, it will get an error. The expression | |
1304 | @code{(buffer-name (process-buffer @var{process}))} returns @code{nil} | |
1305 | if the buffer is dead. | |
1306 | ||
1307 | The output to the function may come in chunks of any size. A program | |
1308 | that produces the same output twice in a row may send it as one batch of | |
1309 | 200 characters one time, and five batches of 40 characters the next. If | |
1310 | the filter looks for certain text strings in the subprocess output, make | |
1311 | sure to handle the case where one of these strings is split across two | |
1312 | or more batches of output. | |
1313 | ||
1314 | @defun set-process-filter process filter | |
1315 | This function gives @var{process} the filter function @var{filter}. If | |
1316 | @var{filter} is @code{nil}, it gives the process no filter. | |
1317 | @end defun | |
1318 | ||
1319 | @defun process-filter process | |
1320 | This function returns the filter function of @var{process}, or @code{nil} | |
1321 | if it has none. | |
1322 | @end defun | |
1323 | ||
1324 | Here is an example of use of a filter function: | |
1325 | ||
1326 | @smallexample | |
1327 | @group | |
1328 | (defun keep-output (process output) | |
1329 | (setq kept (cons output kept))) | |
1330 | @result{} keep-output | |
1331 | @end group | |
1332 | @group | |
1333 | (setq kept nil) | |
1334 | @result{} nil | |
1335 | @end group | |
1336 | @group | |
1337 | (set-process-filter (get-process "shell") 'keep-output) | |
1338 | @result{} keep-output | |
1339 | @end group | |
1340 | @group | |
1341 | (process-send-string "shell" "ls ~/other\n") | |
1342 | @result{} nil | |
1343 | kept | |
1344 | @result{} ("lewis@@slug[8] % " | |
1345 | @end group | |
1346 | @group | |
1347 | "FINAL-W87-SHORT.MSS backup.otl kolstad.mss~ | |
1348 | address.txt backup.psf kolstad.psf | |
1349 | backup.bib~ david.mss resume-Dec-86.mss~ | |
1350 | backup.err david.psf resume-Dec.psf | |
1351 | backup.mss dland syllabus.mss | |
1352 | " | |
1353 | "#backups.mss# backup.mss~ kolstad.mss | |
1354 | ") | |
1355 | @end group | |
1356 | @end smallexample | |
1357 | ||
1358 | @ignore @c The code in this example doesn't show the right way to do things. | |
1359 | Here is another, more realistic example, which demonstrates how to use | |
1360 | the process mark to do insertion in the same fashion as is done when | |
1361 | there is no filter function: | |
1362 | ||
1363 | @smallexample | |
1364 | @group | |
1365 | ;; @r{Insert input in the buffer specified by @code{my-shell-buffer}} | |
1366 | ;; @r{and make sure that buffer is shown in some window.} | |
1367 | (defun my-process-filter (proc str) | |
1368 | (let ((cur (selected-window)) | |
1369 | (pop-up-windows t)) | |
1370 | (pop-to-buffer my-shell-buffer) | |
1371 | @end group | |
1372 | @group | |
1373 | (goto-char (point-max)) | |
1374 | (insert str) | |
1375 | (set-marker (process-mark proc) (point-max)) | |
1376 | (select-window cur))) | |
1377 | @end group | |
1378 | @end smallexample | |
1379 | @end ignore | |
1380 | ||
1381 | @node Decoding Output | |
1382 | @subsection Decoding Process Output | |
1383 | @cindex decode process output | |
1384 | ||
1385 | When Emacs writes process output directly into a multibyte buffer, | |
1386 | it decodes the output according to the process output coding system. | |
1387 | If the coding system is @code{raw-text} or @code{no-conversion}, Emacs | |
1388 | converts the unibyte output to multibyte using | |
1389 | @code{string-to-multibyte}, and inserts the resulting multibyte text. | |
1390 | ||
1391 | You can use @code{set-process-coding-system} to specify which coding | |
1392 | system to use (@pxref{Process Information}). Otherwise, the coding | |
1393 | system comes from @code{coding-system-for-read}, if that is | |
1394 | non-@code{nil}; or else from the defaulting mechanism (@pxref{Default | |
1395 | Coding Systems}). | |
1396 | ||
1397 | @strong{Warning:} Coding systems such as @code{undecided} which | |
1398 | determine the coding system from the data do not work entirely | |
1399 | reliably with asynchronous subprocess output. This is because Emacs | |
1400 | has to process asynchronous subprocess output in batches, as it | |
1401 | arrives. Emacs must try to detect the proper coding system from one | |
1402 | batch at a time, and this does not always work. Therefore, if at all | |
1403 | possible, specify a coding system that determines both the character | |
1404 | code conversion and the end of line conversion---that is, one like | |
1405 | @code{latin-1-unix}, rather than @code{undecided} or @code{latin-1}. | |
1406 | ||
4972c361 SM |
1407 | @c Let's keep the index entries that were there for |
1408 | @c set-process-filter-multibyte and process-filter-multibyte-p, | |
b8d4c8d0 GM |
1409 | @cindex filter multibyte flag, of process |
1410 | @cindex process filter multibyte flag | |
1411 | When Emacs calls a process filter function, it provides the process | |
1412 | output as a multibyte string or as a unibyte string according to the | |
4972c361 SM |
1413 | process's filter coding system. Emacs |
1414 | decodes the output according to the process output coding system, | |
1415 | which usually produces a multibyte string, except for coding systems | |
1416 | such as @code{binary} and @code{raw-text} | |
b8d4c8d0 GM |
1417 | |
1418 | @node Accepting Output | |
1419 | @subsection Accepting Output from Processes | |
1420 | @cindex accept input from processes | |
1421 | ||
1422 | Output from asynchronous subprocesses normally arrives only while | |
1423 | Emacs is waiting for some sort of external event, such as elapsed time | |
1424 | or terminal input. Occasionally it is useful in a Lisp program to | |
1425 | explicitly permit output to arrive at a specific point, or even to wait | |
1426 | until output arrives from a process. | |
1427 | ||
1428 | @defun accept-process-output &optional process seconds millisec just-this-one | |
1429 | This function allows Emacs to read pending output from processes. The | |
1430 | output is inserted in the associated buffers or given to their filter | |
1431 | functions. If @var{process} is non-@code{nil} then this function does | |
1432 | not return until some output has been received from @var{process}. | |
1433 | ||
1434 | @c Emacs 19 feature | |
1435 | The arguments @var{seconds} and @var{millisec} let you specify timeout | |
1436 | periods. The former specifies a period measured in seconds and the | |
1437 | latter specifies one measured in milliseconds. The two time periods | |
1438 | thus specified are added together, and @code{accept-process-output} | |
1439 | returns after that much time, whether or not there has been any | |
1440 | subprocess output. | |
1441 | ||
1442 | The argument @var{millisec} is semi-obsolete nowadays because | |
1443 | @var{seconds} can be a floating point number to specify waiting a | |
1444 | fractional number of seconds. If @var{seconds} is 0, the function | |
1445 | accepts whatever output is pending but does not wait. | |
1446 | ||
1447 | @c Emacs 22.1 feature | |
1448 | If @var{process} is a process, and the argument @var{just-this-one} is | |
1449 | non-@code{nil}, only output from that process is handled, suspending output | |
1450 | from other processes until some output has been received from that | |
1451 | process or the timeout expires. If @var{just-this-one} is an integer, | |
1452 | also inhibit running timers. This feature is generally not | |
1453 | recommended, but may be necessary for specific applications, such as | |
1454 | speech synthesis. | |
1455 | ||
1456 | The function @code{accept-process-output} returns non-@code{nil} if it | |
1457 | did get some output, or @code{nil} if the timeout expired before output | |
1458 | arrived. | |
1459 | @end defun | |
1460 | ||
1461 | @node Sentinels | |
1462 | @section Sentinels: Detecting Process Status Changes | |
1463 | @cindex process sentinel | |
1464 | @cindex sentinel (of process) | |
1465 | ||
1466 | A @dfn{process sentinel} is a function that is called whenever the | |
1467 | associated process changes status for any reason, including signals | |
1468 | (whether sent by Emacs or caused by the process's own actions) that | |
1469 | terminate, stop, or continue the process. The process sentinel is | |
1470 | also called if the process exits. The sentinel receives two | |
1471 | arguments: the process for which the event occurred, and a string | |
1472 | describing the type of event. | |
1473 | ||
1474 | The string describing the event looks like one of the following: | |
1475 | ||
1476 | @itemize @bullet | |
1477 | @item | |
1478 | @code{"finished\n"}. | |
1479 | ||
1480 | @item | |
1481 | @code{"exited abnormally with code @var{exitcode}\n"}. | |
1482 | ||
1483 | @item | |
1484 | @code{"@var{name-of-signal}\n"}. | |
1485 | ||
1486 | @item | |
1487 | @code{"@var{name-of-signal} (core dumped)\n"}. | |
1488 | @end itemize | |
1489 | ||
1490 | A sentinel runs only while Emacs is waiting (e.g., for terminal | |
1491 | input, or for time to elapse, or for process output). This avoids the | |
1492 | timing errors that could result from running them at random places in | |
1493 | the middle of other Lisp programs. A program can wait, so that | |
1494 | sentinels will run, by calling @code{sit-for} or @code{sleep-for} | |
1495 | (@pxref{Waiting}), or @code{accept-process-output} (@pxref{Accepting | |
1496 | Output}). Emacs also allows sentinels to run when the command loop is | |
1497 | reading input. @code{delete-process} calls the sentinel when it | |
1498 | terminates a running process. | |
1499 | ||
1500 | Emacs does not keep a queue of multiple reasons to call the sentinel | |
1501 | of one process; it records just the current status and the fact that | |
1502 | there has been a change. Therefore two changes in status, coming in | |
1503 | quick succession, can call the sentinel just once. However, process | |
1504 | termination will always run the sentinel exactly once. This is | |
1505 | because the process status can't change again after termination. | |
1506 | ||
1507 | Emacs explicitly checks for output from the process before running | |
1508 | the process sentinel. Once the sentinel runs due to process | |
1509 | termination, no further output can arrive from the process. | |
1510 | ||
1511 | A sentinel that writes the output into the buffer of the process | |
1512 | should check whether the buffer is still alive. If it tries to insert | |
1513 | into a dead buffer, it will get an error. If the buffer is dead, | |
1514 | @code{(buffer-name (process-buffer @var{process}))} returns @code{nil}. | |
1515 | ||
1516 | Quitting is normally inhibited within a sentinel---otherwise, the | |
1517 | effect of typing @kbd{C-g} at command level or to quit a user command | |
1518 | would be unpredictable. If you want to permit quitting inside a | |
1519 | sentinel, bind @code{inhibit-quit} to @code{nil}. In most cases, the | |
1520 | right way to do this is with the macro @code{with-local-quit}. | |
1521 | @xref{Quitting}. | |
1522 | ||
1523 | If an error happens during execution of a sentinel, it is caught | |
1524 | automatically, so that it doesn't stop the execution of whatever | |
1525 | programs was running when the sentinel was started. However, if | |
1526 | @code{debug-on-error} is non-@code{nil}, the error-catching is turned | |
1527 | off. This makes it possible to use the Lisp debugger to debug the | |
1528 | sentinel. @xref{Debugger}. | |
1529 | ||
1530 | While a sentinel is running, the process sentinel is temporarily | |
1531 | set to @code{nil} so that the sentinel won't run recursively. | |
1532 | For this reason it is not possible for a sentinel to specify | |
1533 | a new sentinel. | |
1534 | ||
1535 | In earlier Emacs versions, every sentinel that did regular expression | |
1536 | searching or matching had to explicitly save and restore the match data. | |
1537 | Now Emacs does this automatically for sentinels; they never need to do | |
1538 | it explicitly. @xref{Match Data}. | |
1539 | ||
1540 | @defun set-process-sentinel process sentinel | |
1541 | This function associates @var{sentinel} with @var{process}. If | |
1542 | @var{sentinel} is @code{nil}, then the process will have no sentinel. | |
1543 | The default behavior when there is no sentinel is to insert a message in | |
1544 | the process's buffer when the process status changes. | |
1545 | ||
1546 | Changes in process sentinel take effect immediately---if the sentinel | |
1547 | is slated to be run but has not been called yet, and you specify a new | |
1548 | sentinel, the eventual call to the sentinel will use the new one. | |
1549 | ||
1550 | @smallexample | |
1551 | @group | |
1552 | (defun msg-me (process event) | |
1553 | (princ | |
1554 | (format "Process: %s had the event `%s'" process event))) | |
1555 | (set-process-sentinel (get-process "shell") 'msg-me) | |
1556 | @result{} msg-me | |
1557 | @end group | |
1558 | @group | |
1559 | (kill-process (get-process "shell")) | |
1560 | @print{} Process: #<process shell> had the event `killed' | |
1561 | @result{} #<process shell> | |
1562 | @end group | |
1563 | @end smallexample | |
1564 | @end defun | |
1565 | ||
1566 | @defun process-sentinel process | |
1567 | This function returns the sentinel of @var{process}, or @code{nil} if it | |
1568 | has none. | |
1569 | @end defun | |
1570 | ||
1571 | @defun waiting-for-user-input-p | |
1572 | While a sentinel or filter function is running, this function returns | |
1573 | non-@code{nil} if Emacs was waiting for keyboard input from the user at | |
1574 | the time the sentinel or filter function was called, @code{nil} if it | |
1575 | was not. | |
1576 | @end defun | |
1577 | ||
1578 | @node Query Before Exit | |
1579 | @section Querying Before Exit | |
1580 | ||
1581 | When Emacs exits, it terminates all its subprocesses by sending them | |
1582 | the @code{SIGHUP} signal. Because subprocesses may be doing | |
1583 | valuable work, Emacs normally asks the user to confirm that it is ok | |
1584 | to terminate them. Each process has a query flag which, if | |
1585 | non-@code{nil}, says that Emacs should ask for confirmation before | |
1586 | exiting and thus killing that process. The default for the query flag | |
1587 | is @code{t}, meaning @emph{do} query. | |
1588 | ||
1589 | @defun process-query-on-exit-flag process | |
1590 | This returns the query flag of @var{process}. | |
1591 | @end defun | |
1592 | ||
1593 | @defun set-process-query-on-exit-flag process flag | |
1594 | This function sets the query flag of @var{process} to @var{flag}. It | |
1595 | returns @var{flag}. | |
1596 | ||
1597 | @smallexample | |
1598 | @group | |
1599 | ;; @r{Don't query about the shell process} | |
1600 | (set-process-query-on-exit-flag (get-process "shell") nil) | |
1601 | @result{} t | |
1602 | @end group | |
1603 | @end smallexample | |
1604 | @end defun | |
1605 | ||
1606 | @defun process-kill-without-query process &optional do-query | |
1607 | This function clears the query flag of @var{process}, so that | |
1608 | Emacs will not query the user on account of that process. | |
1609 | ||
1610 | Actually, the function does more than that: it returns the old value of | |
1611 | the process's query flag, and sets the query flag to @var{do-query}. | |
1612 | Please don't use this function to do those things any more---please | |
1613 | use the newer, cleaner functions @code{process-query-on-exit-flag} and | |
1614 | @code{set-process-query-on-exit-flag} in all but the simplest cases. | |
1615 | The only way you should use @code{process-kill-without-query} nowadays | |
1616 | is like this: | |
1617 | ||
1618 | @smallexample | |
1619 | @group | |
1620 | ;; @r{Don't query about the shell process} | |
1621 | (process-kill-without-query (get-process "shell")) | |
1622 | @end group | |
1623 | @end smallexample | |
1624 | @end defun | |
1625 | ||
23dd4ecd EZ |
1626 | @node System Processes |
1627 | @section Accessing Other Processes | |
1628 | @cindex system processes | |
1629 | ||
1630 | In addition to accessing and manipulating processes that are | |
1631 | subprocesses of the current Emacs session, Emacs Lisp programs can | |
1632 | also access other processes running on the same machine. We call | |
1633 | these @dfn{system processes}, to distinguish between them and Emacs | |
1634 | subprocesses. | |
1635 | ||
1636 | Emacs provides several primitives for accessing system processes. | |
1637 | Not all platforms support these primitives; on those which don't, | |
1638 | these primitives return @code{nil}. | |
1639 | ||
1640 | @defun list-system-processes | |
1641 | This function returns a list of all the processes running on the | |
1642 | system. Each process is identified by its @acronym{PID}, a numerical | |
1643 | process ID that is assigned by the OS and distinguishes the process | |
1644 | from all the other processes running on the same machine at the same | |
1645 | time. | |
1646 | @end defun | |
1647 | ||
1648 | @defun system-process-attributes pid | |
1649 | This function returns an alist of attributes for the process specified | |
1650 | by its process ID @var{pid}. Each association in the alist is of the | |
1651 | form @code{(@var{key} . @var{value})}, where @var{key} designates the | |
1652 | attribute and @var{value} is the value of that attribute. The various | |
1653 | attribute @var{key}'s that this function can return are listed below. | |
1654 | Not all platforms support all of these attributes; if an attribute is | |
1655 | not supported, its association will not appear in the returned alist. | |
1656 | Values that are numbers can be either integer or floating-point, | |
1657 | depending on the magnitude of the value. | |
1658 | ||
1659 | @table @code | |
1660 | @item euid | |
1661 | The effective user ID of the user who invoked the process. The | |
1662 | corresponding @var{value} is a number. If the process was invoked by | |
1663 | the same user who runs the current Emacs session, the value is | |
1664 | identical to what @code{user-uid} returns (@pxref{User | |
1665 | Identification}). | |
1666 | ||
1667 | @item user | |
1668 | User name corresponding to the process's effective user ID, a string. | |
1669 | ||
1670 | @item egid | |
1671 | The group ID of the effective user ID, a number. | |
1672 | ||
1673 | @item group | |
1674 | Group name corresponding to the effective user's group ID, a string. | |
1675 | ||
1676 | @item comm | |
1677 | The name of the command that runs in the process. This is a string | |
1678 | that usually specifies the name of the executable file of the process, | |
1679 | without the leading directories. However, some special system | |
1680 | processes can report strings that do not correspond to an executable | |
1681 | file of a program. | |
1682 | ||
1683 | @item state | |
1684 | The state code of the process. This is a short string that encodes | |
1685 | the scheduling state of the process. Here's a list of the most | |
1686 | frequently seen codes: | |
1687 | ||
1688 | @table @code | |
1dca458f | 1689 | @item "D" |
23dd4ecd | 1690 | uninterruptible sleep (usually I/O) |
1dca458f | 1691 | @item "R" |
23dd4ecd | 1692 | running |
1dca458f | 1693 | @item "S" |
23dd4ecd | 1694 | interruptible sleep (waiting for some event) |
1dca458f | 1695 | @item "T" |
23dd4ecd | 1696 | stopped, e.g., by a job control signal |
1dca458f EZ |
1697 | @item "Z" |
1698 | ``zombie'': a process that terminated, but was not reaped by its parent | |
23dd4ecd EZ |
1699 | @end table |
1700 | ||
1701 | @noindent | |
1702 | For the full list of the possible states, see the manual page of the | |
1703 | @command{ps} command. | |
1704 | ||
1705 | @item ppid | |
1706 | The process ID of the parent process, a number. | |
1707 | ||
1708 | @item pgrp | |
1709 | The process group ID of the process, a number. | |
1710 | ||
1711 | @item sess | |
1712 | The session ID of the process. This is a number that is the process | |
1713 | ID of the process's @dfn{session leader}. | |
1714 | ||
1715 | @item ttname | |
1716 | A string that is the name of the process's controlling terminal. On | |
1717 | Unix and GNU systems, this is normally the file name of the | |
1718 | corresponding terminal device, such as @file{/dev/pts65}. | |
1719 | ||
1720 | @item tpgid | |
1721 | The numerical process group ID of the foreground process group that | |
1722 | uses the process's terminal. | |
1723 | ||
1724 | @item minflt | |
1725 | The number of minor page faults caused by the process since its | |
1726 | beginning. (Minor page faults are those that don't involve reading | |
1727 | from disk.) | |
1728 | ||
1729 | @item majflt | |
1730 | The number of major page faults caused by the process since its | |
1731 | beginning. (Major page faults require a disk to be read, and are thus | |
1732 | more expensive than minor page faults.) | |
1733 | ||
1734 | @item cminflt | |
1735 | @itemx cmajflt | |
1736 | Like @code{minflt} and @code{majflt}, but include the number of page | |
1737 | faults for all the child processes of the given process. | |
1738 | ||
1739 | @item utime | |
1740 | Time spent by the process in the user context, for running the | |
1741 | application's code. The corresponding @var{value} is in the | |
1742 | @w{@code{(@var{high} @var{low} @var{microsec})}} format, the same | |
1743 | format used by functions @code{current-time} (@pxref{Time of Day, | |
1744 | current-time}) and @code{file-attributes} (@pxref{File Attributes}). | |
1745 | ||
1746 | @item stime | |
1747 | Time spent by the process in the system (kernel) context, for | |
1748 | processing system calls. The corresponding @var{value} is in the same | |
1749 | format as for @code{utime}. | |
1750 | ||
1751 | @item cutime | |
1752 | @itemx cstime | |
1753 | Like @code{utime} and @code{stime}, but includes the times of all the | |
1754 | child processes of the given process. | |
1755 | ||
1756 | @item pri | |
1757 | The numerical priority of the process. | |
1758 | ||
1759 | @item nice | |
1dca458f EZ |
1760 | The @dfn{nice value} of the process, a number. (Processes with smaller |
1761 | nice values get scheduled more favorably.) | |
23dd4ecd EZ |
1762 | |
1763 | @item thcount | |
1764 | The number of threads in the process. | |
1765 | ||
1766 | @item start | |
1767 | The time the process was started, in the @w{@code{(@var{high} | |
1768 | @var{low} @var{microsec})}} format used by @code{current-time} and | |
1769 | @code{file-attributes}. | |
1770 | ||
1771 | @item etime | |
1772 | The time elapsed since the process started, in the @w{@code{(@var{high} | |
1773 | @var{low} @var{microsec})}} format. | |
1774 | ||
1775 | @item vsize | |
1776 | The virtual memory size of the process, measured in kilobytes. | |
1777 | ||
1778 | @item rss | |
1779 | The size of the process's @dfn{resident set}, the number of kilobytes | |
1780 | occupied by the process in the machine's physical memory. | |
1781 | ||
1782 | @item pcpu | |
1783 | The percentage of the CPU time used by the process since it started. | |
1784 | The corresponding @var{value} is a floating-point number between 0 and | |
1785 | 100. | |
1786 | ||
1787 | @item pmem | |
1788 | The percentage of the total physical memory installed on the machine | |
1789 | used by the process's resident set. The value is a floating-point | |
1790 | number between 0 and 100. | |
1791 | ||
1792 | @item args | |
1793 | The command-line with which the process was invoked. This is a string | |
1794 | in which individual command-line arguments are separated by blanks; | |
1795 | whitespace characters that are embedded in the arguments are quoted as | |
1796 | appropriate for the system's shell: escaped by backslash characters on | |
1797 | GNU and Unix, and enclosed in double quote characters on Windows. | |
1798 | Thus, this command-line string can be directly used in primitives such | |
1799 | as @code{shell-command}. | |
1800 | @end table | |
1801 | ||
1802 | @end defun | |
1803 | ||
1804 | ||
b8d4c8d0 GM |
1805 | @node Transaction Queues |
1806 | @section Transaction Queues | |
1807 | @cindex transaction queue | |
1808 | ||
1809 | You can use a @dfn{transaction queue} to communicate with a subprocess | |
1810 | using transactions. First use @code{tq-create} to create a transaction | |
1811 | queue communicating with a specified process. Then you can call | |
1812 | @code{tq-enqueue} to send a transaction. | |
1813 | ||
1814 | @defun tq-create process | |
1815 | This function creates and returns a transaction queue communicating with | |
1816 | @var{process}. The argument @var{process} should be a subprocess | |
1817 | capable of sending and receiving streams of bytes. It may be a child | |
1818 | process, or it may be a TCP connection to a server, possibly on another | |
1819 | machine. | |
1820 | @end defun | |
1821 | ||
1822 | @defun tq-enqueue queue question regexp closure fn &optional delay-question | |
1823 | This function sends a transaction to queue @var{queue}. Specifying the | |
1824 | queue has the effect of specifying the subprocess to talk to. | |
1825 | ||
1826 | The argument @var{question} is the outgoing message that starts the | |
1827 | transaction. The argument @var{fn} is the function to call when the | |
1828 | corresponding answer comes back; it is called with two arguments: | |
1829 | @var{closure}, and the answer received. | |
1830 | ||
1831 | The argument @var{regexp} is a regular expression that should match | |
1832 | text at the end of the entire answer, but nothing before; that's how | |
1833 | @code{tq-enqueue} determines where the answer ends. | |
1834 | ||
1835 | If the argument @var{delay-question} is non-nil, delay sending this | |
1836 | question until the process has finished replying to any previous | |
1837 | questions. This produces more reliable results with some processes. | |
1838 | ||
1839 | The return value of @code{tq-enqueue} itself is not meaningful. | |
1840 | @end defun | |
1841 | ||
1842 | @defun tq-close queue | |
1843 | Shut down transaction queue @var{queue}, waiting for all pending transactions | |
1844 | to complete, and then terminate the connection or child process. | |
1845 | @end defun | |
1846 | ||
1847 | Transaction queues are implemented by means of a filter function. | |
1848 | @xref{Filter Functions}. | |
1849 | ||
1850 | @node Network | |
1851 | @section Network Connections | |
1852 | @cindex network connection | |
1853 | @cindex TCP | |
1854 | @cindex UDP | |
1855 | ||
1856 | Emacs Lisp programs can open stream (TCP) and datagram (UDP) network | |
1857 | connections to other processes on the same machine or other machines. | |
1858 | A network connection is handled by Lisp much like a subprocess, and is | |
1859 | represented by a process object. However, the process you are | |
1860 | communicating with is not a child of the Emacs process, so it has no | |
1861 | process @acronym{ID}, and you can't kill it or send it signals. All you | |
1862 | can do is send and receive data. @code{delete-process} closes the | |
1863 | connection, but does not kill the program at the other end; that | |
1864 | program must decide what to do about closure of the connection. | |
1865 | ||
1866 | Lisp programs can listen for connections by creating network | |
1867 | servers. A network server is also represented by a kind of process | |
1868 | object, but unlike a network connection, the network server never | |
1869 | transfers data itself. When it receives a connection request, it | |
1870 | creates a new network connection to represent the connection just | |
1871 | made. (The network connection inherits certain information, including | |
1872 | the process plist, from the server.) The network server then goes | |
1873 | back to listening for more connection requests. | |
1874 | ||
1875 | Network connections and servers are created by calling | |
1876 | @code{make-network-process} with an argument list consisting of | |
1877 | keyword/argument pairs, for example @code{:server t} to create a | |
1878 | server process, or @code{:type 'datagram} to create a datagram | |
1879 | connection. @xref{Low-Level Network}, for details. You can also use | |
1880 | the @code{open-network-stream} function described below. | |
1881 | ||
c73e02fa GM |
1882 | To distinguish the different types of processes, the |
1883 | @code{process-type} function returns the symbol @code{network} for a | |
1884 | network connection or server, @code{serial} for a serial port | |
1885 | connection, or @code{real} for a real subprocess. | |
1886 | ||
1887 | The @code{process-status} function returns @code{open}, | |
1888 | @code{closed}, @code{connect}, and @code{failed} for network | |
1889 | connections. For a network server, the status is always | |
b8d4c8d0 GM |
1890 | @code{listen}. None of those values is possible for a real |
1891 | subprocess. @xref{Process Information}. | |
1892 | ||
1893 | You can stop and resume operation of a network process by calling | |
1894 | @code{stop-process} and @code{continue-process}. For a server | |
1895 | process, being stopped means not accepting new connections. (Up to 5 | |
1896 | connection requests will be queued for when you resume the server; you | |
1897 | can increase this limit, unless it is imposed by the operating | |
1898 | system.) For a network stream connection, being stopped means not | |
1899 | processing input (any arriving input waits until you resume the | |
1900 | connection). For a datagram connection, some number of packets may be | |
1901 | queued but input may be lost. You can use the function | |
1902 | @code{process-command} to determine whether a network connection or | |
1903 | server is stopped; a non-@code{nil} value means yes. | |
1904 | ||
1905 | @defun open-network-stream name buffer-or-name host service | |
1906 | This function opens a TCP connection, and returns a process object | |
1907 | that represents the connection. | |
1908 | ||
1909 | The @var{name} argument specifies the name for the process object. It | |
1910 | is modified as necessary to make it unique. | |
1911 | ||
1912 | The @var{buffer-or-name} argument is the buffer to associate with the | |
1913 | connection. Output from the connection is inserted in the buffer, | |
1914 | unless you specify a filter function to handle the output. If | |
1915 | @var{buffer-or-name} is @code{nil}, it means that the connection is not | |
1916 | associated with any buffer. | |
1917 | ||
1918 | The arguments @var{host} and @var{service} specify where to connect to; | |
1919 | @var{host} is the host name (a string), and @var{service} is the name of | |
1920 | a defined network service (a string) or a port number (an integer). | |
1921 | @end defun | |
1922 | ||
b8d4c8d0 GM |
1923 | @node Network Servers |
1924 | @section Network Servers | |
1925 | @cindex network servers | |
1926 | ||
1927 | You create a server by calling @code{make-network-process} with | |
1928 | @code{:server t}. The server will listen for connection requests from | |
1929 | clients. When it accepts a client connection request, that creates a | |
1930 | new network connection, itself a process object, with the following | |
1931 | parameters: | |
1932 | ||
1933 | @itemize @bullet | |
1934 | @item | |
1935 | The connection's process name is constructed by concatenating the | |
1936 | server process' @var{name} with a client identification string. The | |
1937 | client identification string for an IPv4 connection looks like | |
1938 | @samp{<@var{a}.@var{b}.@var{c}.@var{d}:@var{p}>}. Otherwise, it is a | |
1939 | unique number in brackets, as in @samp{<@var{nnn}>}. The number | |
1940 | is unique for each connection in the Emacs session. | |
1941 | ||
1942 | @item | |
1943 | If the server's filter is non-@code{nil}, the connection process does | |
1944 | not get a separate process buffer; otherwise, Emacs creates a new | |
1945 | buffer for the purpose. The buffer name is the server's buffer name | |
1946 | or process name, concatenated with the client identification string. | |
1947 | ||
1948 | The server's process buffer value is never used directly by Emacs, but | |
1949 | it is passed to the log function, which can log connections by | |
1950 | inserting text there. | |
1951 | ||
1952 | @item | |
1953 | The communication type and the process filter and sentinel are | |
1954 | inherited from those of the server. The server never directly | |
1955 | uses its filter and sentinel; their sole purpose is to initialize | |
1956 | connections made to the server. | |
1957 | ||
1958 | @item | |
1959 | The connection's process contact info is set according to the client's | |
1960 | addressing information (typically an IP address and a port number). | |
1961 | This information is associated with the @code{process-contact} | |
1962 | keywords @code{:host}, @code{:service}, @code{:remote}. | |
1963 | ||
1964 | @item | |
1965 | The connection's local address is set up according to the port | |
1966 | number used for the connection. | |
1967 | ||
1968 | @item | |
1969 | The client process' plist is initialized from the server's plist. | |
1970 | @end itemize | |
1971 | ||
1972 | @node Datagrams | |
1973 | @section Datagrams | |
1974 | @cindex datagrams | |
1975 | ||
1976 | A datagram connection communicates with individual packets rather | |
1977 | than streams of data. Each call to @code{process-send} sends one | |
1978 | datagram packet (@pxref{Input to Processes}), and each datagram | |
1979 | received results in one call to the filter function. | |
1980 | ||
1981 | The datagram connection doesn't have to talk with the same remote | |
1982 | peer all the time. It has a @dfn{remote peer address} which specifies | |
1983 | where to send datagrams to. Each time an incoming datagram is passed | |
1984 | to the filter function, the peer address is set to the address that | |
1985 | datagram came from; that way, if the filter function sends a datagram, | |
1986 | it will go back to that place. You can specify the remote peer | |
1987 | address when you create the datagram connection using the | |
1988 | @code{:remote} keyword. You can change it later on by calling | |
1989 | @code{set-process-datagram-address}. | |
1990 | ||
1991 | @defun process-datagram-address process | |
1992 | If @var{process} is a datagram connection or server, this function | |
1993 | returns its remote peer address. | |
1994 | @end defun | |
1995 | ||
1996 | @defun set-process-datagram-address process address | |
1997 | If @var{process} is a datagram connection or server, this function | |
1998 | sets its remote peer address to @var{address}. | |
1999 | @end defun | |
2000 | ||
2001 | @node Low-Level Network | |
2002 | @section Low-Level Network Access | |
2003 | ||
2004 | You can also create network connections by operating at a lower | |
2005 | level than that of @code{open-network-stream}, using | |
2006 | @code{make-network-process}. | |
2007 | ||
2008 | @menu | |
2009 | * Proc: Network Processes. Using @code{make-network-process}. | |
2010 | * Options: Network Options. Further control over network connections. | |
2011 | * Features: Network Feature Testing. | |
2012 | Determining which network features work on | |
2013 | the machine you are using. | |
2014 | @end menu | |
2015 | ||
2016 | @node Network Processes | |
2017 | @subsection @code{make-network-process} | |
2018 | ||
2019 | The basic function for creating network connections and network | |
2020 | servers is @code{make-network-process}. It can do either of those | |
2021 | jobs, depending on the arguments you give it. | |
2022 | ||
2023 | @defun make-network-process &rest args | |
2024 | This function creates a network connection or server and returns the | |
2025 | process object that represents it. The arguments @var{args} are a | |
2026 | list of keyword/argument pairs. Omitting a keyword is always | |
2027 | equivalent to specifying it with value @code{nil}, except for | |
2028 | @code{:coding}, @code{:filter-multibyte}, and @code{:reuseaddr}. Here | |
2029 | are the meaningful keywords: | |
2030 | ||
2031 | @table @asis | |
2032 | @item :name @var{name} | |
2033 | Use the string @var{name} as the process name. It is modified if | |
2034 | necessary to make it unique. | |
2035 | ||
2036 | @item :type @var{type} | |
2037 | Specify the communication type. A value of @code{nil} specifies a | |
2038 | stream connection (the default); @code{datagram} specifies a datagram | |
2039 | connection. Both connections and servers can be of either type. | |
2040 | ||
2041 | @item :server @var{server-flag} | |
2042 | If @var{server-flag} is non-@code{nil}, create a server. Otherwise, | |
2043 | create a connection. For a stream type server, @var{server-flag} may | |
2044 | be an integer which then specifies the length of the queue of pending | |
2045 | connections to the server. The default queue length is 5. | |
2046 | ||
2047 | @item :host @var{host} | |
2048 | Specify the host to connect to. @var{host} should be a host name or | |
2049 | Internet address, as a string, or the symbol @code{local} to specify | |
2050 | the local host. If you specify @var{host} for a server, it must | |
2051 | specify a valid address for the local host, and only clients | |
2052 | connecting to that address will be accepted. | |
2053 | ||
2054 | @item :service @var{service} | |
2055 | @var{service} specifies a port number to connect to, or, for a server, | |
2056 | the port number to listen on. It should be a service name that | |
2057 | translates to a port number, or an integer specifying the port number | |
2058 | directly. For a server, it can also be @code{t}, which means to let | |
2059 | the system select an unused port number. | |
2060 | ||
2061 | @item :family @var{family} | |
2062 | @var{family} specifies the address (and protocol) family for | |
2063 | communication. @code{nil} means determine the proper address family | |
2064 | automatically for the given @var{host} and @var{service}. | |
2065 | @code{local} specifies a Unix socket, in which case @var{host} is | |
2066 | ignored. @code{ipv4} and @code{ipv6} specify to use IPv4 and IPv6 | |
2067 | respectively. | |
2068 | ||
2069 | @item :local @var{local-address} | |
2070 | For a server process, @var{local-address} is the address to listen on. | |
2071 | It overrides @var{family}, @var{host} and @var{service}, and you | |
2072 | may as well not specify them. | |
2073 | ||
2074 | @item :remote @var{remote-address} | |
2075 | For a connection, @var{remote-address} is the address to connect to. | |
2076 | It overrides @var{family}, @var{host} and @var{service}, and you | |
2077 | may as well not specify them. | |
2078 | ||
2079 | For a datagram server, @var{remote-address} specifies the initial | |
2080 | setting of the remote datagram address. | |
2081 | ||
2082 | The format of @var{local-address} or @var{remote-address} depends on | |
2083 | the address family: | |
2084 | ||
2085 | @itemize - | |
2086 | @item | |
2087 | An IPv4 address is represented as a five-element vector of four 8-bit | |
2088 | integers and one 16-bit integer | |
2089 | @code{[@var{a} @var{b} @var{c} @var{d} @var{p}]} corresponding to | |
2090 | numeric IPv4 address @var{a}.@var{b}.@var{c}.@var{d} and port number | |
2091 | @var{p}. | |
2092 | ||
2093 | @item | |
2094 | An IPv6 address is represented as a nine-element vector of 16-bit | |
2095 | integers @code{[@var{a} @var{b} @var{c} @var{d} @var{e} @var{f} | |
2096 | @var{g} @var{h} @var{p}]} corresponding to numeric IPv6 address | |
2097 | @var{a}:@var{b}:@var{c}:@var{d}:@var{e}:@var{f}:@var{g}:@var{h} and | |
2098 | port number @var{p}. | |
2099 | ||
2100 | @item | |
2101 | A local address is represented as a string which specifies the address | |
2102 | in the local address space. | |
2103 | ||
2104 | @item | |
2105 | An ``unsupported family'' address is represented by a cons | |
2106 | @code{(@var{f} . @var{av})}, where @var{f} is the family number and | |
2107 | @var{av} is a vector specifying the socket address using one element | |
2108 | per address data byte. Do not rely on this format in portable code, | |
2109 | as it may depend on implementation defined constants, data sizes, and | |
2110 | data structure alignment. | |
2111 | @end itemize | |
2112 | ||
2113 | @item :nowait @var{bool} | |
2114 | If @var{bool} is non-@code{nil} for a stream connection, return | |
2115 | without waiting for the connection to complete. When the connection | |
2116 | succeeds or fails, Emacs will call the sentinel function, with a | |
2117 | second argument matching @code{"open"} (if successful) or | |
2118 | @code{"failed"}. The default is to block, so that | |
2119 | @code{make-network-process} does not return until the connection | |
2120 | has succeeded or failed. | |
2121 | ||
2122 | @item :stop @var{stopped} | |
2123 | Start the network connection or server in the `stopped' state if | |
2124 | @var{stopped} is non-@code{nil}. | |
2125 | ||
2126 | @item :buffer @var{buffer} | |
2127 | Use @var{buffer} as the process buffer. | |
2128 | ||
2129 | @item :coding @var{coding} | |
2130 | Use @var{coding} as the coding system for this process. To specify | |
2131 | different coding systems for decoding data from the connection and for | |
2132 | encoding data sent to it, specify @code{(@var{decoding} . | |
2133 | @var{encoding})} for @var{coding}. | |
2134 | ||
2135 | If you don't specify this keyword at all, the default | |
2136 | is to determine the coding systems from the data. | |
2137 | ||
2138 | @item :noquery @var{query-flag} | |
2139 | Initialize the process query flag to @var{query-flag}. | |
2140 | @xref{Query Before Exit}. | |
2141 | ||
2142 | @item :filter @var{filter} | |
2143 | Initialize the process filter to @var{filter}. | |
2144 | ||
2145 | @item :filter-multibyte @var{bool} | |
2146 | If @var{bool} is non-@code{nil}, strings given to the process filter | |
2147 | are multibyte, otherwise they are unibyte. If you don't specify this | |
2148 | keyword at all, the default is that the strings are multibyte if | |
2149 | @code{default-enable-multibyte-characters} is non-@code{nil}. | |
2150 | ||
2151 | @item :sentinel @var{sentinel} | |
2152 | Initialize the process sentinel to @var{sentinel}. | |
2153 | ||
2154 | @item :log @var{log} | |
2155 | Initialize the log function of a server process to @var{log}. The log | |
2156 | function is called each time the server accepts a network connection | |
2157 | from a client. The arguments passed to the log function are | |
2158 | @var{server}, @var{connection}, and @var{message}, where @var{server} | |
2159 | is the server process, @var{connection} is the new process for the | |
2160 | connection, and @var{message} is a string describing what has | |
2161 | happened. | |
2162 | ||
2163 | @item :plist @var{plist} | |
2164 | Initialize the process plist to @var{plist}. | |
2165 | @end table | |
2166 | ||
2167 | The original argument list, modified with the actual connection | |
2168 | information, is available via the @code{process-contact} function. | |
2169 | @end defun | |
2170 | ||
2171 | @node Network Options | |
2172 | @subsection Network Options | |
2173 | ||
2174 | The following network options can be specified when you create a | |
2175 | network process. Except for @code{:reuseaddr}, you can also set or | |
2176 | modify these options later, using @code{set-network-process-option}. | |
2177 | ||
2178 | For a server process, the options specified with | |
2179 | @code{make-network-process} are not inherited by the client | |
2180 | connections, so you will need to set the necessary options for each | |
2181 | child connection as it is created. | |
2182 | ||
2183 | @table @asis | |
2184 | @item :bindtodevice @var{device-name} | |
2185 | If @var{device-name} is a non-empty string identifying a network | |
2186 | interface name (see @code{network-interface-list}), only handle | |
2187 | packets received on that interface. If @var{device-name} is @code{nil} | |
2188 | (the default), handle packets received on any interface. | |
2189 | ||
2190 | Using this option may require special privileges on some systems. | |
2191 | ||
2192 | @item :broadcast @var{broadcast-flag} | |
2193 | If @var{broadcast-flag} is non-@code{nil} for a datagram process, the | |
2194 | process will receive datagram packet sent to a broadcast address, and | |
2195 | be able to send packets to a broadcast address. Ignored for a stream | |
2196 | connection. | |
2197 | ||
2198 | @item :dontroute @var{dontroute-flag} | |
2199 | If @var{dontroute-flag} is non-@code{nil}, the process can only send | |
2200 | to hosts on the same network as the local host. | |
2201 | ||
2202 | @item :keepalive @var{keepalive-flag} | |
2203 | If @var{keepalive-flag} is non-@code{nil} for a stream connection, | |
2204 | enable exchange of low-level keep-alive messages. | |
2205 | ||
2206 | @item :linger @var{linger-arg} | |
2207 | If @var{linger-arg} is non-@code{nil}, wait for successful | |
2208 | transmission of all queued packets on the connection before it is | |
2209 | deleted (see @code{delete-process}). If @var{linger-arg} is an | |
2210 | integer, it specifies the maximum time in seconds to wait for queued | |
2211 | packets to be sent before closing the connection. Default is | |
2212 | @code{nil} which means to discard unsent queued packets when the | |
2213 | process is deleted. | |
2214 | ||
2215 | @item :oobinline @var{oobinline-flag} | |
2216 | If @var{oobinline-flag} is non-@code{nil} for a stream connection, | |
2217 | receive out-of-band data in the normal data stream. Otherwise, ignore | |
2218 | out-of-band data. | |
2219 | ||
2220 | @item :priority @var{priority} | |
2221 | Set the priority for packets sent on this connection to the integer | |
2222 | @var{priority}. The interpretation of this number is protocol | |
2223 | specific, such as setting the TOS (type of service) field on IP | |
2224 | packets sent on this connection. It may also have system dependent | |
2225 | effects, such as selecting a specific output queue on the network | |
2226 | interface. | |
2227 | ||
2228 | @item :reuseaddr @var{reuseaddr-flag} | |
2229 | If @var{reuseaddr-flag} is non-@code{nil} (the default) for a stream | |
2230 | server process, allow this server to reuse a specific port number (see | |
2231 | @code{:service}) unless another process on this host is already | |
2232 | listening on that port. If @var{reuseaddr-flag} is @code{nil}, there | |
2233 | may be a period of time after the last use of that port (by any | |
2234 | process on the host), where it is not possible to make a new server on | |
2235 | that port. | |
2236 | @end table | |
2237 | ||
2238 | @defun set-network-process-option process option value | |
2239 | This function sets or modifies a network option for network process | |
2240 | @var{process}. See @code{make-network-process} for details of options | |
2241 | @var{option} and their corresponding values @var{value}. | |
2242 | ||
2243 | The current setting of an option is available via the | |
2244 | @code{process-contact} function. | |
2245 | @end defun | |
2246 | ||
2247 | @node Network Feature Testing | |
2248 | @subsection Testing Availability of Network Features | |
2249 | ||
2250 | To test for the availability of a given network feature, use | |
2251 | @code{featurep} like this: | |
2252 | ||
2253 | @example | |
2254 | (featurep 'make-network-process '(@var{keyword} @var{value})) | |
2255 | @end example | |
2256 | ||
2257 | @noindent | |
2258 | The result of the first form is @code{t} if it works to specify | |
2259 | @var{keyword} with value @var{value} in @code{make-network-process}. | |
2260 | The result of the second form is @code{t} if @var{keyword} is | |
2261 | supported by @code{make-network-process}. Here are some of the | |
2262 | @var{keyword}---@var{value} pairs you can test in | |
2263 | this way. | |
2264 | ||
2265 | @table @code | |
2266 | @item (:nowait t) | |
2267 | Non-@code{nil} if non-blocking connect is supported. | |
2268 | @item (:type datagram) | |
2269 | Non-@code{nil} if datagrams are supported. | |
2270 | @item (:family local) | |
2271 | Non-@code{nil} if local (a.k.a.@: ``UNIX domain'') sockets are supported. | |
2272 | @item (:family ipv6) | |
2273 | Non-@code{nil} if IPv6 is supported. | |
2274 | @item (:service t) | |
2275 | Non-@code{nil} if the system can select the port for a server. | |
2276 | @end table | |
2277 | ||
2278 | To test for the availability of a given network option, use | |
2279 | @code{featurep} like this: | |
2280 | ||
2281 | @example | |
2282 | (featurep 'make-network-process '@var{keyword}) | |
2283 | @end example | |
2284 | ||
2285 | @noindent | |
2286 | Here are some of the options you can test in this way. | |
2287 | ||
2288 | @table @code | |
2289 | @item :bindtodevice | |
2290 | @itemx :broadcast | |
2291 | @itemx :dontroute | |
2292 | @itemx :keepalive | |
2293 | @itemx :linger | |
2294 | @itemx :oobinline | |
2295 | @itemx :priority | |
2296 | @itemx :reuseaddr | |
2297 | That particular network option is supported by | |
2298 | @code{make-network-process} and @code{set-network-process-option}. | |
2299 | @end table | |
2300 | ||
2301 | @node Misc Network | |
2302 | @section Misc Network Facilities | |
2303 | ||
2304 | These additional functions are useful for creating and operating | |
305a7ef2 EZ |
2305 | on network connections. Note that they are supported only on some |
2306 | systems. | |
b8d4c8d0 GM |
2307 | |
2308 | @defun network-interface-list | |
2309 | This function returns a list describing the network interfaces | |
2310 | of the machine you are using. The value is an alist whose | |
2311 | elements have the form @code{(@var{name} . @var{address})}. | |
2312 | @var{address} has the same form as the @var{local-address} | |
2313 | and @var{remote-address} arguments to @code{make-network-process}. | |
2314 | @end defun | |
2315 | ||
2316 | @defun network-interface-info ifname | |
2317 | This function returns information about the network interface named | |
2318 | @var{ifname}. The value is a list of the form | |
2319 | @code{(@var{addr} @var{bcast} @var{netmask} @var{hwaddr} @var{flags})}. | |
2320 | ||
2321 | @table @var | |
2322 | @item addr | |
2323 | The Internet protocol address. | |
2324 | @item bcast | |
2325 | The broadcast address. | |
2326 | @item netmask | |
2327 | The network mask. | |
2328 | @item hwaddr | |
2329 | The layer 2 address (Ethernet MAC address, for instance). | |
2330 | @item flags | |
2331 | The current flags of the interface. | |
2332 | @end table | |
2333 | @end defun | |
2334 | ||
2335 | @defun format-network-address address &optional omit-port | |
2336 | This function converts the Lisp representation of a network address to | |
2337 | a string. | |
2338 | ||
2339 | A five-element vector @code{[@var{a} @var{b} @var{c} @var{d} @var{p}]} | |
2340 | represents an IPv4 address @var{a}.@var{b}.@var{c}.@var{d} and port | |
2341 | number @var{p}. @code{format-network-address} converts that to the | |
2342 | string @code{"@var{a}.@var{b}.@var{c}.@var{d}:@var{p}"}. | |
2343 | ||
2344 | A nine-element vector @code{[@var{a} @var{b} @var{c} @var{d} @var{e} | |
2345 | @var{f} @var{g} @var{h} @var{p}]} represents an IPv6 address along | |
2346 | with a port number. @code{format-network-address} converts that to | |
2347 | the string | |
2348 | @code{"[@var{a}:@var{b}:@var{c}:@var{d}:@var{e}:@var{f}:@var{g}:@var{h}]:@var{p}"}. | |
2349 | ||
2350 | If the vector does not include the port number, @var{p}, or if | |
2351 | @var{omit-port} is non-@code{nil}, the result does not include the | |
2352 | @code{:@var{p}} suffix. | |
2353 | @end defun | |
2354 | ||
c73e02fa GM |
2355 | @node Serial Ports |
2356 | @section Communicating with Serial Ports | |
2357 | @cindex @file{/dev/tty} | |
2358 | @cindex @file{COM1} | |
2359 | ||
2360 | Emacs can communicate with serial ports. For interactive use, | |
2361 | @kbd{M-x serial-term} opens a terminal window. In a Lisp program, | |
2362 | @code{make-serial-process} creates a process object. | |
2363 | ||
2364 | The serial port can be configured at run-time, without having to | |
2365 | close and re-open it. The function @code{serial-process-configure} | |
2366 | lets you change the speed, bytesize, and other parameters. In a | |
2367 | terminal window created by @code{serial-term}, you can click on the | |
2368 | mode line for configuration. | |
2369 | ||
2370 | A serial connection is represented by a process object which can be | |
2371 | used similar to a subprocess or network process. You can send and | |
2372 | receive data and configure the serial port. A serial process object | |
2373 | has no process ID, and you can't send signals to it. | |
2374 | @code{delete-process} on the process object or @code{kill-buffer} on | |
2375 | the process buffer close the connection, but this does not affect the | |
2376 | device connected to the serial port. | |
2377 | ||
2378 | The function @code{process-type} returns the symbol @code{serial} | |
2379 | for a process object representing a serial port. | |
2380 | ||
2381 | Serial ports are available on GNU/Linux, Unix, and Windows systems. | |
2382 | ||
2383 | @defun serial-term port speed | |
2384 | Start a terminal-emulator for a serial port in a new buffer. | |
2385 | @var{port} is the path or name of the serial port. For example, this | |
2386 | could be @file{/dev/ttyS0} on Unix. On Windows, this could be | |
2387 | @file{COM1}, or @file{\\.\COM10} (double the backslashes in strings). | |
2388 | ||
2389 | @var{speed} is the speed of the serial port in bits per second. 9600 | |
2390 | is a common value. The buffer is in Term mode; see @code{term-mode} | |
2391 | for the commands to use in that buffer. You can change the speed and | |
2392 | the configuration in the mode line menu. @end defun | |
2393 | ||
2394 | @defun make-serial-process &rest args | |
2395 | @code{make-serial-process} creates a process and a buffer. Arguments | |
2396 | are specified as keyword/argument pairs. The following arguments are | |
2397 | defined: | |
2398 | ||
2399 | @table @code | |
2400 | @item :port port | |
2401 | @var{port} (mandatory) is the path or name of the serial port. | |
2402 | For example, this could be @file{/dev/ttyS0} on Unix. On Windows, | |
2403 | this could be @file{COM1}, or @file{\\.\COM10} for ports higher than | |
2404 | @file{COM9} (double the backslashes in strings). | |
2405 | ||
2406 | @item :speed speed | |
2407 | @var{speed} (mandatory) is handled by @code{serial-process-configure}, | |
2408 | which is called by @code{make-serial-process}. | |
2409 | ||
2410 | @item :name name | |
2411 | @var{name} is the name of the process. If @var{name} is not given, the | |
2412 | value of @var{port} is used. | |
2413 | ||
2414 | @item :buffer buffer | |
2415 | @var{buffer} is the buffer (or buffer-name) to associate with the | |
2416 | process. Process output goes at the end of that buffer, unless you | |
2417 | specify an output stream or filter function to handle the output. If | |
2418 | @var{buffer} is not given, the value of @var{name} is used. | |
2419 | ||
2420 | @item :coding coding | |
2421 | If @var{coding} is a symbol, it specifies the coding system used for | |
2422 | both reading and writing for this process. If @var{coding} is a cons | |
2423 | @code{(decoding . encoding)}, @var{decoding} is used for reading, and | |
2424 | @var{encoding} is used for writing. | |
2425 | ||
2426 | @item :noquery bool | |
2427 | When exiting Emacs, query the user if @var{bool} is @code{nil} and the | |
2428 | process is running. If @var{bool} is not given, query before exiting. | |
2429 | ||
2430 | @item :stop bool | |
2431 | Start process in the @code{stopped} state if @var{bool} is | |
2432 | non-@code{nil}. In the stopped state, a serial process does not | |
2433 | accept incoming data, but you can send outgoing data. The stopped | |
2434 | state is cleared by @code{continue-process} and set by | |
2435 | @code{stop-process}. | |
2436 | ||
2437 | @item :filter filter | |
2438 | Install @var{filter} as the process filter. | |
2439 | ||
2440 | @item :sentinel sentinel | |
2441 | Install @var{sentinel} as the process sentinel. | |
2442 | ||
2443 | @item :plist plist | |
2444 | Install @var{plist} as the initial plist of the process. | |
2445 | ||
2446 | @item :speed | |
2447 | @itemx :bytesize | |
2448 | @itemx :parity | |
2449 | @itemx :stopbits | |
2450 | @itemx :flowcontrol | |
2451 | These arguments are handled by @code{serial-process-configure}, which | |
2452 | is called by @code{make-serial-process}. | |
2453 | @end table | |
2454 | ||
2455 | The original argument list, possibly modified by later configuration, | |
2456 | is available via the function @code{process-contact}. | |
2457 | ||
2458 | Examples: | |
2459 | ||
2460 | @example | |
2461 | (make-serial-process :port "/dev/ttyS0" :speed 9600) | |
2462 | ||
2463 | (make-serial-process :port "COM1" :speed 115200 :stopbits 2) | |
2464 | ||
2465 | (make-serial-process :port "\\\\.\\COM13" :speed 1200 :bytesize 7 :parity 'odd) | |
2466 | ||
2467 | (make-serial-process :port "/dev/tty.BlueConsole-SPP-1" :speed nil) | |
2468 | @end example | |
2469 | @end defun | |
2470 | ||
2471 | @defun serial-process-configure &rest args | |
2472 | @cindex baud | |
2473 | @cindex bytesize | |
2474 | @cindex parity | |
2475 | @cindex stopbits | |
2476 | @cindex flowcontrol | |
2477 | ||
2478 | Configure a serial port. Arguments are specified as keyword/argument | |
2479 | pairs. Attributes that are not given are re-initialized from the | |
2480 | process's current configuration (available via the function | |
2481 | @code{process-contact}) or set to reasonable default values. The | |
2482 | following arguments are defined: | |
2483 | ||
2484 | @table @code | |
2485 | @item :process process | |
2486 | @itemx :name name | |
2487 | @itemx :buffer buffer | |
2488 | @itemx :port port | |
2489 | Any of these arguments can be given to identify the process that is to | |
2490 | be configured. If none of these arguments is given, the current | |
2491 | buffer's process is used. | |
2492 | ||
2493 | @item :speed @var{speed} | |
2494 | @var{speed} is the speed of the serial port in bits per second, also | |
2495 | called baud rate. Any value can be given for @var{speed}, but most | |
2496 | serial ports work only at a few defined values between 1200 and | |
2497 | 115200, with 9600 being the most common value. If @var{speed} is | |
2498 | @code{nil}, the serial port is not configured any further, i.e., all | |
2499 | other arguments are ignored. This may be useful for special serial | |
2500 | ports such as Bluetooth-to-serial converters which can only be | |
2501 | configured through AT commands. A value of @code{nil} for @var{speed} | |
2502 | can be used only when passed through @code{make-serial-process} or | |
2503 | @code{serial-term}. | |
2504 | ||
2505 | @item :bytesize @var{bytesize} | |
2506 | @var{bytesize} is the number of bits per byte, which can be 7 or 8. | |
2507 | If @var{bytesize} is not given or @code{nil}, a value of 8 is used. | |
2508 | ||
2509 | @item :parity @var{parity} | |
2510 | @var{parity} can be @code{nil} (don't use parity), the symbol | |
2511 | @code{odd} (use odd parity), or the symbol @code{even} (use even | |
2512 | parity). If @var{parity} is not given, no parity is used. | |
2513 | ||
2514 | @item :stopbits @var{stopbits} | |
2515 | @var{stopbits} is the number of stopbits used to terminate a byte | |
2516 | transmission. @var{stopbits} can be 1 or 2. If @var{stopbits} is not | |
2517 | given or @code{nil}, 1 stopbit is used. | |
2518 | ||
2519 | @item :flowcontrol @var{flowcontrol} | |
2520 | @var{flowcontrol} determines the type of flowcontrol to be used, which | |
2521 | is either @code{nil} (don't use flowcontrol), the symbol @code{hw} | |
2522 | (use RTS/CTS hardware flowcontrol), or the symbol @code{sw} (use | |
2523 | XON/XOFF software flowcontrol). If @var{flowcontrol} is not given, no | |
2524 | flowcontrol is used. | |
2525 | @end table | |
2526 | ||
2527 | @code{serial-process-configure} is called by @code{make-serial-process} for the | |
2528 | initial configuration of the serial port. | |
2529 | ||
2530 | Examples: | |
2531 | ||
2532 | @example | |
2533 | (serial-process-configure :process "/dev/ttyS0" :speed 1200) | |
2534 | ||
2535 | (serial-process-configure :buffer "COM1" :stopbits 1 :parity 'odd :flowcontrol 'hw) | |
2536 | ||
2537 | (serial-process-configure :port "\\\\.\\COM13" :bytesize 7) | |
2538 | @end example | |
2539 | @end defun | |
2540 | ||
b8d4c8d0 GM |
2541 | @node Byte Packing |
2542 | @section Packing and Unpacking Byte Arrays | |
2543 | @cindex byte packing and unpacking | |
2544 | ||
2545 | This section describes how to pack and unpack arrays of bytes, | |
2546 | usually for binary network protocols. These functions convert byte arrays | |
2547 | to alists, and vice versa. The byte array can be represented as a | |
2548 | unibyte string or as a vector of integers, while the alist associates | |
2549 | symbols either with fixed-size objects or with recursive sub-alists. | |
2550 | ||
2551 | @cindex serializing | |
2552 | @cindex deserializing | |
2553 | @cindex packing | |
2554 | @cindex unpacking | |
2555 | Conversion from byte arrays to nested alists is also known as | |
2556 | @dfn{deserializing} or @dfn{unpacking}, while going in the opposite | |
2557 | direction is also known as @dfn{serializing} or @dfn{packing}. | |
2558 | ||
2559 | @menu | |
2560 | * Bindat Spec:: Describing data layout. | |
2561 | * Bindat Functions:: Doing the unpacking and packing. | |
2562 | * Bindat Examples:: Samples of what bindat.el can do for you! | |
2563 | @end menu | |
2564 | ||
2565 | @node Bindat Spec | |
2566 | @subsection Describing Data Layout | |
2567 | ||
2568 | To control unpacking and packing, you write a @dfn{data layout | |
2569 | specification}, a special nested list describing named and typed | |
2570 | @dfn{fields}. This specification controls length of each field to be | |
2571 | processed, and how to pack or unpack it. We normally keep bindat specs | |
2572 | in variables whose names end in @samp{-bindat-spec}; that kind of name | |
2573 | is automatically recognized as ``risky.'' | |
2574 | ||
2575 | @cindex endianness | |
2576 | @cindex big endian | |
2577 | @cindex little endian | |
2578 | @cindex network byte ordering | |
2579 | A field's @dfn{type} describes the size (in bytes) of the object | |
2580 | that the field represents and, in the case of multibyte fields, how | |
2581 | the bytes are ordered within the field. The two possible orderings | |
2582 | are ``big endian'' (also known as ``network byte ordering'') and | |
2583 | ``little endian.'' For instance, the number @code{#x23cd} (decimal | |
2584 | 9165) in big endian would be the two bytes @code{#x23} @code{#xcd}; | |
2585 | and in little endian, @code{#xcd} @code{#x23}. Here are the possible | |
2586 | type values: | |
2587 | ||
2588 | @table @code | |
2589 | @item u8 | |
2590 | @itemx byte | |
2591 | Unsigned byte, with length 1. | |
2592 | ||
2593 | @item u16 | |
2594 | @itemx word | |
2595 | @itemx short | |
2596 | Unsigned integer in network byte order, with length 2. | |
2597 | ||
2598 | @item u24 | |
2599 | Unsigned integer in network byte order, with length 3. | |
2600 | ||
2601 | @item u32 | |
2602 | @itemx dword | |
2603 | @itemx long | |
2604 | Unsigned integer in network byte order, with length 4. | |
2605 | Note: These values may be limited by Emacs' integer implementation limits. | |
2606 | ||
2607 | @item u16r | |
2608 | @itemx u24r | |
2609 | @itemx u32r | |
2610 | Unsigned integer in little endian order, with length 2, 3 and 4, respectively. | |
2611 | ||
2612 | @item str @var{len} | |
2613 | String of length @var{len}. | |
2614 | ||
2615 | @item strz @var{len} | |
2616 | Zero-terminated string, in a fixed-size field with length @var{len}. | |
2617 | ||
2618 | @item vec @var{len} [@var{type}] | |
2619 | Vector of @var{len} elements of type @var{type}, or bytes if not | |
2620 | @var{type} is specified. | |
2621 | The @var{type} is any of the simple types above, or another vector | |
2622 | specified as a list @code{(vec @var{len} [@var{type}])}. | |
2623 | ||
2624 | @item ip | |
2625 | Four-byte vector representing an Internet address. For example: | |
2626 | @code{[127 0 0 1]} for localhost. | |
2627 | ||
2628 | @item bits @var{len} | |
2629 | List of set bits in @var{len} bytes. The bytes are taken in big | |
2630 | endian order and the bits are numbered starting with @code{8 * | |
2631 | @var{len} @minus{} 1} and ending with zero. For example: @code{bits | |
2632 | 2} unpacks @code{#x28} @code{#x1c} to @code{(2 3 4 11 13)} and | |
2633 | @code{#x1c} @code{#x28} to @code{(3 5 10 11 12)}. | |
2634 | ||
2635 | @item (eval @var{form}) | |
2636 | @var{form} is a Lisp expression evaluated at the moment the field is | |
2637 | unpacked or packed. The result of the evaluation should be one of the | |
2638 | above-listed type specifications. | |
2639 | @end table | |
2640 | ||
2641 | For a fixed-size field, the length @var{len} is given as an integer | |
2642 | specifying the number of bytes in the field. | |
2643 | ||
2644 | When the length of a field is not fixed, it typically depends on the | |
2645 | value of a preceding field. In this case, the length @var{len} can be | |
2646 | given either as a list @code{(@var{name} ...)} identifying a | |
2647 | @dfn{field name} in the format specified for @code{bindat-get-field} | |
2648 | below, or by an expression @code{(eval @var{form})} where @var{form} | |
2649 | should evaluate to an integer, specifying the field length. | |
2650 | ||
2651 | A field specification generally has the form @code{([@var{name}] | |
2652 | @var{handler})}. The square braces indicate that @var{name} is | |
2653 | optional. (Don't use names that are symbols meaningful as type | |
2654 | specifications (above) or handler specifications (below), since that | |
2655 | would be ambiguous.) @var{name} can be a symbol or the expression | |
2656 | @code{(eval @var{form})}, in which case @var{form} should evaluate to | |
2657 | a symbol. | |
2658 | ||
2659 | @var{handler} describes how to unpack or pack the field and can be one | |
2660 | of the following: | |
2661 | ||
2662 | @table @code | |
2663 | @item @var{type} | |
2664 | Unpack/pack this field according to the type specification @var{type}. | |
2665 | ||
2666 | @item eval @var{form} | |
2667 | Evaluate @var{form}, a Lisp expression, for side-effect only. If the | |
2668 | field name is specified, the value is bound to that field name. | |
2669 | ||
2670 | @item fill @var{len} | |
2671 | Skip @var{len} bytes. In packing, this leaves them unchanged, | |
2672 | which normally means they remain zero. In unpacking, this means | |
2673 | they are ignored. | |
2674 | ||
2675 | @item align @var{len} | |
2676 | Skip to the next multiple of @var{len} bytes. | |
2677 | ||
2678 | @item struct @var{spec-name} | |
2679 | Process @var{spec-name} as a sub-specification. This describes a | |
2680 | structure nested within another structure. | |
2681 | ||
2682 | @item union @var{form} (@var{tag} @var{spec})@dots{} | |
2683 | @c ??? I don't see how one would actually use this. | |
2684 | @c ??? what kind of expression would be useful for @var{form}? | |
2685 | Evaluate @var{form}, a Lisp expression, find the first @var{tag} | |
2686 | that matches it, and process its associated data layout specification | |
2687 | @var{spec}. Matching can occur in one of three ways: | |
2688 | ||
2689 | @itemize | |
2690 | @item | |
2691 | If a @var{tag} has the form @code{(eval @var{expr})}, evaluate | |
2692 | @var{expr} with the variable @code{tag} dynamically bound to the value | |
2693 | of @var{form}. A non-@code{nil} result indicates a match. | |
2694 | ||
2695 | @item | |
2696 | @var{tag} matches if it is @code{equal} to the value of @var{form}. | |
2697 | ||
2698 | @item | |
2699 | @var{tag} matches unconditionally if it is @code{t}. | |
2700 | @end itemize | |
2701 | ||
2702 | @item repeat @var{count} @var{field-specs}@dots{} | |
2703 | Process the @var{field-specs} recursively, in order, then repeat | |
2704 | starting from the first one, processing all the specs @var{count} | |
2705 | times overall. The @var{count} is given using the same formats as a | |
2706 | field length---if an @code{eval} form is used, it is evaluated just once. | |
2707 | For correct operation, each spec in @var{field-specs} must include a name. | |
2708 | @end table | |
2709 | ||
2710 | For the @code{(eval @var{form})} forms used in a bindat specification, | |
2711 | the @var{form} can access and update these dynamically bound variables | |
2712 | during evaluation: | |
2713 | ||
2714 | @table @code | |
2715 | @item last | |
2716 | Value of the last field processed. | |
2717 | ||
2718 | @item bindat-raw | |
2719 | The data as a byte array. | |
2720 | ||
2721 | @item bindat-idx | |
2722 | Current index (within @code{bindat-raw}) for unpacking or packing. | |
2723 | ||
2724 | @item struct | |
2725 | The alist containing the structured data that have been unpacked so | |
2726 | far, or the entire structure being packed. You can use | |
2727 | @code{bindat-get-field} to access specific fields of this structure. | |
2728 | ||
2729 | @item count | |
2730 | @itemx index | |
2731 | Inside a @code{repeat} block, these contain the maximum number of | |
2732 | repetitions (as specified by the @var{count} parameter), and the | |
2733 | current repetition number (counting from 0). Setting @code{count} to | |
2734 | zero will terminate the inner-most repeat block after the current | |
2735 | repetition has completed. | |
2736 | @end table | |
2737 | ||
2738 | @node Bindat Functions | |
2739 | @subsection Functions to Unpack and Pack Bytes | |
2740 | ||
2741 | In the following documentation, @var{spec} refers to a data layout | |
2742 | specification, @code{bindat-raw} to a byte array, and @var{struct} to an | |
2743 | alist representing unpacked field data. | |
2744 | ||
2745 | @defun bindat-unpack spec bindat-raw &optional bindat-idx | |
2746 | This function unpacks data from the unibyte string or byte | |
2747 | array @code{bindat-raw} | |
2748 | according to @var{spec}. Normally this starts unpacking at the | |
2749 | beginning of the byte array, but if @var{bindat-idx} is non-@code{nil}, it | |
2750 | specifies a zero-based starting position to use instead. | |
2751 | ||
2752 | The value is an alist or nested alist in which each element describes | |
2753 | one unpacked field. | |
2754 | @end defun | |
2755 | ||
2756 | @defun bindat-get-field struct &rest name | |
2757 | This function selects a field's data from the nested alist | |
2758 | @var{struct}. Usually @var{struct} was returned by | |
2759 | @code{bindat-unpack}. If @var{name} corresponds to just one argument, | |
2760 | that means to extract a top-level field value. Multiple @var{name} | |
2761 | arguments specify repeated lookup of sub-structures. An integer name | |
2762 | acts as an array index. | |
2763 | ||
2764 | For example, if @var{name} is @code{(a b 2 c)}, that means to find | |
2765 | field @code{c} in the third element of subfield @code{b} of field | |
2766 | @code{a}. (This corresponds to @code{struct.a.b[2].c} in C.) | |
2767 | @end defun | |
2768 | ||
2769 | Although packing and unpacking operations change the organization of | |
2770 | data (in memory), they preserve the data's @dfn{total length}, which is | |
2771 | the sum of all the fields' lengths, in bytes. This value is not | |
2772 | generally inherent in either the specification or alist alone; instead, | |
2773 | both pieces of information contribute to its calculation. Likewise, the | |
2774 | length of a string or array being unpacked may be longer than the data's | |
2775 | total length as described by the specification. | |
2776 | ||
2777 | @defun bindat-length spec struct | |
2778 | This function returns the total length of the data in @var{struct}, | |
2779 | according to @var{spec}. | |
2780 | @end defun | |
2781 | ||
2782 | @defun bindat-pack spec struct &optional bindat-raw bindat-idx | |
2783 | This function returns a byte array packed according to @var{spec} from | |
2784 | the data in the alist @var{struct}. Normally it creates and fills a | |
2785 | new byte array starting at the beginning. However, if @var{bindat-raw} | |
2786 | is non-@code{nil}, it specifies a pre-allocated unibyte string or vector to | |
2787 | pack into. If @var{bindat-idx} is non-@code{nil}, it specifies the starting | |
2788 | offset for packing into @code{bindat-raw}. | |
2789 | ||
2790 | When pre-allocating, you should make sure @code{(length @var{bindat-raw})} | |
2791 | meets or exceeds the total length to avoid an out-of-range error. | |
2792 | @end defun | |
2793 | ||
2794 | @defun bindat-ip-to-string ip | |
2795 | Convert the Internet address vector @var{ip} to a string in the usual | |
2796 | dotted notation. | |
2797 | ||
2798 | @example | |
2799 | (bindat-ip-to-string [127 0 0 1]) | |
2800 | @result{} "127.0.0.1" | |
2801 | @end example | |
2802 | @end defun | |
2803 | ||
2804 | @node Bindat Examples | |
2805 | @subsection Examples of Byte Unpacking and Packing | |
2806 | ||
2807 | Here is a complete example of byte unpacking and packing: | |
2808 | ||
2809 | @lisp | |
2810 | (defvar fcookie-index-spec | |
2811 | '((:version u32) | |
2812 | (:count u32) | |
2813 | (:longest u32) | |
2814 | (:shortest u32) | |
2815 | (:flags u32) | |
2816 | (:delim u8) | |
2817 | (:ignored fill 3) | |
2818 | (:offset repeat (:count) | |
2819 | (:foo u32))) | |
2820 | "Description of a fortune cookie index file's contents.") | |
2821 | ||
2822 | (defun fcookie (cookies &optional index) | |
2823 | "Display a random fortune cookie from file COOKIES. | |
2824 | Optional second arg INDEX specifies the associated index | |
2825 | filename, which is by default constructed by appending | |
2826 | \".dat\" to COOKIES. Display cookie text in possibly | |
2827 | new buffer \"*Fortune Cookie: BASENAME*\" where BASENAME | |
2828 | is COOKIES without the directory part." | |
2829 | (interactive "fCookies file: ") | |
2830 | (let* ((info (with-temp-buffer | |
2831 | (insert-file-contents-literally | |
2832 | (or index (concat cookies ".dat"))) | |
2833 | (bindat-unpack fcookie-index-spec | |
2834 | (buffer-string)))) | |
2835 | (sel (random (bindat-get-field info :count))) | |
2836 | (beg (cdar (bindat-get-field info :offset sel))) | |
2837 | (end (or (cdar (bindat-get-field info | |
2838 | :offset (1+ sel))) | |
2839 | (nth 7 (file-attributes cookies))))) | |
2840 | (switch-to-buffer | |
2841 | (get-buffer-create | |
2842 | (format "*Fortune Cookie: %s*" | |
2843 | (file-name-nondirectory cookies)))) | |
2844 | (erase-buffer) | |
2845 | (insert-file-contents-literally | |
2846 | cookies nil beg (- end 3)))) | |
2847 | ||
2848 | (defun fcookie-create-index (cookies &optional index delim) | |
2849 | "Scan file COOKIES, and write out its index file. | |
2850 | Optional second arg INDEX specifies the index filename, | |
2851 | which is by default constructed by appending \".dat\" to | |
2852 | COOKIES. Optional third arg DELIM specifies the unibyte | |
2853 | character which, when found on a line of its own in | |
2854 | COOKIES, indicates the border between entries." | |
2855 | (interactive "fCookies file: ") | |
2856 | (setq delim (or delim ?%)) | |
2857 | (let ((delim-line (format "\n%c\n" delim)) | |
2858 | (count 0) | |
2859 | (max 0) | |
2860 | min p q len offsets) | |
2861 | (unless (= 3 (string-bytes delim-line)) | |
2862 | (error "Delimiter cannot be represented in one byte")) | |
2863 | (with-temp-buffer | |
2864 | (insert-file-contents-literally cookies) | |
2865 | (while (and (setq p (point)) | |
2866 | (search-forward delim-line (point-max) t) | |
2867 | (setq len (- (point) 3 p))) | |
2868 | (setq count (1+ count) | |
2869 | max (max max len) | |
2870 | min (min (or min max) len) | |
2871 | offsets (cons (1- p) offsets)))) | |
2872 | (with-temp-buffer | |
2873 | (set-buffer-multibyte nil) | |
2874 | (insert | |
2875 | (bindat-pack | |
2876 | fcookie-index-spec | |
2877 | `((:version . 2) | |
2878 | (:count . ,count) | |
2879 | (:longest . ,max) | |
2880 | (:shortest . ,min) | |
2881 | (:flags . 0) | |
2882 | (:delim . ,delim) | |
2883 | (:offset . ,(mapcar (lambda (o) | |
2884 | (list (cons :foo o))) | |
2885 | (nreverse offsets)))))) | |
2886 | (let ((coding-system-for-write 'raw-text-unix)) | |
2887 | (write-file (or index (concat cookies ".dat"))))))) | |
2888 | @end lisp | |
2889 | ||
2890 | Following is an example of defining and unpacking a complex structure. | |
2891 | Consider the following C structures: | |
2892 | ||
2893 | @example | |
2894 | struct header @{ | |
2895 | unsigned long dest_ip; | |
2896 | unsigned long src_ip; | |
2897 | unsigned short dest_port; | |
2898 | unsigned short src_port; | |
2899 | @}; | |
2900 | ||
2901 | struct data @{ | |
2902 | unsigned char type; | |
2903 | unsigned char opcode; | |
2904 | unsigned short length; /* In network byte order */ | |
2905 | unsigned char id[8]; /* null-terminated string */ | |
2906 | unsigned char data[/* (length + 3) & ~3 */]; | |
2907 | @}; | |
2908 | ||
2909 | struct packet @{ | |
2910 | struct header header; | |
2911 | unsigned long counters[2]; /* In little endian order */ | |
2912 | unsigned char items; | |
2913 | unsigned char filler[3]; | |
2914 | struct data item[/* items */]; | |
2915 | ||
2916 | @}; | |
2917 | @end example | |
2918 | ||
2919 | The corresponding data layout specification: | |
2920 | ||
2921 | @lisp | |
2922 | (setq header-spec | |
2923 | '((dest-ip ip) | |
2924 | (src-ip ip) | |
2925 | (dest-port u16) | |
2926 | (src-port u16))) | |
2927 | ||
2928 | (setq data-spec | |
2929 | '((type u8) | |
2930 | (opcode u8) | |
2931 | (length u16) ;; network byte order | |
2932 | (id strz 8) | |
2933 | (data vec (length)) | |
2934 | (align 4))) | |
2935 | ||
2936 | (setq packet-spec | |
2937 | '((header struct header-spec) | |
2938 | (counters vec 2 u32r) ;; little endian order | |
2939 | (items u8) | |
2940 | (fill 3) | |
2941 | (item repeat (items) | |
2942 | (struct data-spec)))) | |
2943 | @end lisp | |
2944 | ||
2945 | A binary data representation: | |
2946 | ||
2947 | @lisp | |
2948 | (setq binary-data | |
2949 | [ 192 168 1 100 192 168 1 101 01 28 21 32 | |
2950 | 160 134 1 0 5 1 0 0 2 0 0 0 | |
2951 | 2 3 0 5 ?A ?B ?C ?D ?E ?F 0 0 1 2 3 4 5 0 0 0 | |
2952 | 1 4 0 7 ?B ?C ?D ?E ?F ?G 0 0 6 7 8 9 10 11 12 0 ]) | |
2953 | @end lisp | |
2954 | ||
2955 | The corresponding decoded structure: | |
2956 | ||
2957 | @lisp | |
2958 | (setq decoded (bindat-unpack packet-spec binary-data)) | |
2959 | @result{} | |
2960 | ((header | |
2961 | (dest-ip . [192 168 1 100]) | |
2962 | (src-ip . [192 168 1 101]) | |
2963 | (dest-port . 284) | |
2964 | (src-port . 5408)) | |
2965 | (counters . [100000 261]) | |
2966 | (items . 2) | |
2967 | (item ((data . [1 2 3 4 5]) | |
2968 | (id . "ABCDEF") | |
2969 | (length . 5) | |
2970 | (opcode . 3) | |
2971 | (type . 2)) | |
2972 | ((data . [6 7 8 9 10 11 12]) | |
2973 | (id . "BCDEFG") | |
2974 | (length . 7) | |
2975 | (opcode . 4) | |
2976 | (type . 1)))) | |
2977 | @end lisp | |
2978 | ||
2979 | Fetching data from this structure: | |
2980 | ||
2981 | @lisp | |
2982 | (bindat-get-field decoded 'item 1 'id) | |
2983 | @result{} "BCDEFG" | |
2984 | @end lisp | |
2985 | ||
2986 | @ignore | |
2987 | arch-tag: ba9da253-e65f-4e7f-b727-08fba0a1df7a | |
2988 | @end ignore |