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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
651f374c TTN |
3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2002, 2003, |
4 | @c 2004, 2005 Free Software Foundation, Inc. | |
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5 | @c See the file elisp.texi for copying conditions. |
6 | @setfilename ../info/processes | |
969fe9b5 | 7 | @node Processes, Display, Abbrevs, Top |
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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 | |
32 | This function returns @code{t} if @var{object} is a process, | |
33 | @code{nil} otherwise. | |
34 | @end defun | |
35 | ||
36 | @menu | |
37 | * Subprocess Creation:: Functions that start subprocesses. | |
a9f0a989 | 38 | * Shell Arguments:: Quoting an argument to pass it to a shell. |
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39 | * Synchronous Processes:: Details of using synchronous subprocesses. |
40 | * Asynchronous Processes:: Starting up an asynchronous subprocess. | |
41 | * Deleting Processes:: Eliminating an asynchronous subprocess. | |
42 | * Process Information:: Accessing run-status and other attributes. | |
43 | * Input to Processes:: Sending input to an asynchronous subprocess. | |
44 | * Signals to Processes:: Stopping, continuing or interrupting | |
45 | an asynchronous subprocess. | |
46 | * Output from Processes:: Collecting output from an asynchronous subprocess. | |
47 | * Sentinels:: Sentinels run when process run-status changes. | |
edc590bb | 48 | * Query Before Exit:: Whether to query if exiting will kill a process. |
73804d4b | 49 | * Transaction Queues:: Transaction-based communication with subprocesses. |
bfe721d1 | 50 | * Network:: Opening network connections. |
4bb24054 | 51 | * Network Servers:: Network servers let Emacs accept net connections. |
b4b2903b | 52 | * Datagrams:: UDP network connections. |
4bb24054 RS |
53 | * Low-Level Network:: Lower-level but more general function |
54 | to create connections and servers. | |
088767cb | 55 | * Misc Network:: Additional relevant functions for network connections. |
377ddd88 | 56 | * Byte Packing:: Using bindat to pack and unpack binary data. |
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57 | @end menu |
58 | ||
59 | @node Subprocess Creation | |
60 | @section Functions that Create Subprocesses | |
61 | ||
62 | There are three functions that create a new subprocess in which to run | |
63 | a program. One of them, @code{start-process}, creates an asynchronous | |
64 | process and returns a process object (@pxref{Asynchronous Processes}). | |
65 | The other two, @code{call-process} and @code{call-process-region}, | |
66 | create a synchronous process and do not return a process object | |
67 | (@pxref{Synchronous Processes}). | |
68 | ||
8241495d | 69 | Synchronous and asynchronous processes are explained in the following |
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70 | sections. Since the three functions are all called in a similar |
71 | fashion, their common arguments are described here. | |
72 | ||
73 | @cindex execute program | |
74 | @cindex @code{PATH} environment variable | |
75 | @cindex @code{HOME} environment variable | |
76 | In all cases, the function's @var{program} argument specifies the | |
77 | program to be run. An error is signaled if the file is not found or | |
78 | cannot be executed. If the file name is relative, the variable | |
79 | @code{exec-path} contains a list of directories to search. Emacs | |
80 | initializes @code{exec-path} when it starts up, based on the value of | |
81 | the environment variable @code{PATH}. The standard file name | |
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82 | constructs, @samp{~}, @samp{.}, and @samp{..}, are interpreted as |
83 | usual in @code{exec-path}, but environment variable substitutions | |
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84 | (@samp{$HOME}, etc.) are not recognized; use |
85 | @code{substitute-in-file-name} to perform them (@pxref{File Name | |
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86 | Expansion}). @code{nil} in this list refers to |
87 | @code{default-directory}. | |
73804d4b | 88 | |
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89 | Executing a program can also try adding suffixes to the specified |
90 | name: | |
91 | ||
92 | @defvar exec-suffixes | |
93 | This variable is a list of suffixes (strings) to try adding to the | |
94 | specified program file name. The list should include @code{""} if you | |
95 | want the name to be tried exactly as specified. The default value is | |
96 | system-dependent. | |
97 | @end defvar | |
98 | ||
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99 | @strong{Please note:} The argument @var{program} contains only the |
100 | name of the program; it may not contain any command-line arguments. You | |
101 | must use @var{args} to provide those. | |
102 | ||
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103 | Each of the subprocess-creating functions has a @var{buffer-or-name} |
104 | argument which specifies where the standard output from the program will | |
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105 | go. It should be a buffer or a buffer name; if it is a buffer name, |
106 | that will create the buffer if it does not already exist. It can also | |
107 | be @code{nil}, which says to discard the output unless a filter function | |
108 | handles it. (@xref{Filter Functions}, and @ref{Read and Print}.) | |
109 | Normally, you should avoid having multiple processes send output to the | |
110 | same buffer because their output would be intermixed randomly. | |
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111 | |
112 | @cindex program arguments | |
113 | All three of the subprocess-creating functions have a @code{&rest} | |
114 | argument, @var{args}. The @var{args} must all be strings, and they are | |
115 | supplied to @var{program} as separate command line arguments. Wildcard | |
f9f59935 | 116 | characters and other shell constructs have no special meanings in these |
fea5a6d5 | 117 | strings, since the strings are passed directly to the specified program. |
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118 | |
119 | The subprocess gets its current directory from the value of | |
120 | @code{default-directory} (@pxref{File Name Expansion}). | |
121 | ||
122 | @cindex environment variables, subprocesses | |
1911e6e5 | 123 | The subprocess inherits its environment from Emacs, but you can |
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124 | specify overrides for it with @code{process-environment}. @xref{System |
125 | Environment}. | |
126 | ||
177c0ea7 | 127 | @defvar exec-directory |
a9042418 | 128 | @pindex movemail |
8241495d | 129 | The value of this variable is a string, the name of a directory that |
1911e6e5 | 130 | contains programs that come with GNU Emacs, programs intended for Emacs |
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131 | to invoke. The program @code{movemail} is an example of such a program; |
132 | Rmail uses it to fetch new mail from an inbox. | |
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133 | @end defvar |
134 | ||
135 | @defopt exec-path | |
136 | The value of this variable is a list of directories to search for | |
137 | programs to run in subprocesses. Each element is either the name of a | |
138 | directory (i.e., a string), or @code{nil}, which stands for the default | |
139 | directory (which is the value of @code{default-directory}). | |
140 | @cindex program directories | |
141 | ||
142 | The value of @code{exec-path} is used by @code{call-process} and | |
143 | @code{start-process} when the @var{program} argument is not an absolute | |
144 | file name. | |
145 | @end defopt | |
146 | ||
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147 | @node Shell Arguments |
148 | @section Shell Arguments | |
149 | ||
150 | Lisp programs sometimes need to run a shell and give it a command | |
8241495d | 151 | that contains file names that were specified by the user. These |
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152 | programs ought to be able to support any valid file name. But the shell |
153 | gives special treatment to certain characters, and if these characters | |
154 | occur in the file name, they will confuse the shell. To handle these | |
155 | characters, use the function @code{shell-quote-argument}: | |
156 | ||
157 | @defun shell-quote-argument argument | |
158 | This function returns a string which represents, in shell syntax, | |
159 | an argument whose actual contents are @var{argument}. It should | |
160 | work reliably to concatenate the return value into a shell command | |
161 | and then pass it to a shell for execution. | |
162 | ||
163 | Precisely what this function does depends on your operating system. The | |
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164 | function is designed to work with the syntax of your system's standard |
165 | shell; if you use an unusual shell, you will need to redefine this | |
166 | function. | |
969fe9b5 RS |
167 | |
168 | @example | |
169 | ;; @r{This example shows the behavior on GNU and Unix systems.} | |
170 | (shell-quote-argument "foo > bar") | |
171 | @result{} "foo\\ \\>\\ bar" | |
8241495d | 172 | |
342fd6cd | 173 | ;; @r{This example shows the behavior on MS-DOS and MS-Windows.} |
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174 | (shell-quote-argument "foo > bar") |
175 | @result{} "\"foo > bar\"" | |
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176 | @end example |
177 | ||
178 | Here's an example of using @code{shell-quote-argument} to construct | |
179 | a shell command: | |
180 | ||
181 | @example | |
182 | (concat "diff -c " | |
183 | (shell-quote-argument oldfile) | |
184 | " " | |
185 | (shell-quote-argument newfile)) | |
186 | @end example | |
187 | @end defun | |
188 | ||
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189 | @node Synchronous Processes |
190 | @section Creating a Synchronous Process | |
191 | @cindex synchronous subprocess | |
192 | ||
193 | After a @dfn{synchronous process} is created, Emacs waits for the | |
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194 | process to terminate before continuing. Starting Dired on GNU or |
195 | Unix@footnote{On other systems, Emacs uses a Lisp emulation of | |
196 | @code{ls}; see @ref{Contents of Directories}.} is an example of this: it | |
197 | runs @code{ls} in a synchronous process, then modifies the output | |
198 | slightly. Because the process is synchronous, the entire directory | |
199 | listing arrives in the buffer before Emacs tries to do anything with it. | |
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200 | |
201 | While Emacs waits for the synchronous subprocess to terminate, the | |
202 | user can quit by typing @kbd{C-g}. The first @kbd{C-g} tries to kill | |
203 | the subprocess with a @code{SIGINT} signal; but it waits until the | |
204 | subprocess actually terminates before quitting. If during that time the | |
205 | user types another @kbd{C-g}, that kills the subprocess instantly with | |
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206 | @code{SIGKILL} and quits immediately (except on MS-DOS, where killing |
207 | other processes doesn't work). @xref{Quitting}. | |
73804d4b | 208 | |
969fe9b5 RS |
209 | The synchronous subprocess functions return an indication of how the |
210 | process terminated. | |
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211 | |
212 | The output from a synchronous subprocess is generally decoded using a | |
213 | coding system, much like text read from a file. The input sent to a | |
214 | subprocess by @code{call-process-region} is encoded using a coding | |
215 | system, much like text written into a file. @xref{Coding Systems}. | |
73804d4b | 216 | |
22697dac | 217 | @defun call-process program &optional infile destination display &rest args |
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218 | This function calls @var{program} in a separate process and waits for |
219 | it to finish. | |
220 | ||
221 | The standard input for the process comes from file @var{infile} if | |
8241495d | 222 | @var{infile} is not @code{nil}, and from the null device otherwise. |
22697dac KH |
223 | The argument @var{destination} says where to put the process output. |
224 | Here are the possibilities: | |
225 | ||
226 | @table @asis | |
227 | @item a buffer | |
228 | Insert the output in that buffer, before point. This includes both the | |
229 | standard output stream and the standard error stream of the process. | |
230 | ||
231 | @item a string | |
969fe9b5 | 232 | Insert the output in a buffer with that name, before point. |
22697dac KH |
233 | |
234 | @item @code{t} | |
235 | Insert the output in the current buffer, before point. | |
236 | ||
237 | @item @code{nil} | |
238 | Discard the output. | |
239 | ||
240 | @item 0 | |
8241495d | 241 | Discard the output, and return @code{nil} immediately without waiting |
22697dac KH |
242 | for the subprocess to finish. |
243 | ||
244 | In this case, the process is not truly synchronous, since it can run in | |
245 | parallel with Emacs; but you can think of it as synchronous in that | |
246 | Emacs is essentially finished with the subprocess as soon as this | |
247 | function returns. | |
248 | ||
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249 | MS-DOS doesn't support asynchronous subprocesses, so this option doesn't |
250 | work there. | |
251 | ||
1911e6e5 | 252 | @item @code{(@var{real-destination} @var{error-destination})} |
22697dac KH |
253 | Keep the standard output stream separate from the standard error stream; |
254 | deal with the ordinary output as specified by @var{real-destination}, | |
255 | and dispose of the error output according to @var{error-destination}. | |
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256 | If @var{error-destination} is @code{nil}, that means to discard the |
257 | error output, @code{t} means mix it with the ordinary output, and a | |
258 | string specifies a file name to redirect error output into. | |
22697dac KH |
259 | |
260 | You can't directly specify a buffer to put the error output in; that is | |
261 | too difficult to implement. But you can achieve this result by sending | |
262 | the error output to a temporary file and then inserting the file into a | |
263 | buffer. | |
264 | @end table | |
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265 | |
266 | If @var{display} is non-@code{nil}, then @code{call-process} redisplays | |
a9f0a989 RS |
267 | the buffer as output is inserted. (However, if the coding system chosen |
268 | for decoding output is @code{undecided}, meaning deduce the encoding | |
269 | from the actual data, then redisplay sometimes cannot continue once | |
ad800164 | 270 | non-@acronym{ASCII} characters are encountered. There are fundamental |
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271 | reasons why it is hard to fix this; see @ref{Output from Processes}.) |
272 | ||
273 | Otherwise the function @code{call-process} does no redisplay, and the | |
274 | results become visible on the screen only when Emacs redisplays that | |
275 | buffer in the normal course of events. | |
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276 | |
277 | The remaining arguments, @var{args}, are strings that specify command | |
278 | line arguments for the program. | |
279 | ||
280 | The value returned by @code{call-process} (unless you told it not to | |
281 | wait) indicates the reason for process termination. A number gives the | |
282 | exit status of the subprocess; 0 means success, and any other value | |
283 | means failure. If the process terminated with a signal, | |
284 | @code{call-process} returns a string describing the signal. | |
285 | ||
286 | In the examples below, the buffer @samp{foo} is current. | |
287 | ||
288 | @smallexample | |
289 | @group | |
290 | (call-process "pwd" nil t) | |
8241495d | 291 | @result{} 0 |
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292 | |
293 | ---------- Buffer: foo ---------- | |
294 | /usr/user/lewis/manual | |
295 | ---------- Buffer: foo ---------- | |
296 | @end group | |
297 | ||
298 | @group | |
299 | (call-process "grep" nil "bar" nil "lewis" "/etc/passwd") | |
8241495d | 300 | @result{} 0 |
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301 | |
302 | ---------- Buffer: bar ---------- | |
303 | lewis:5LTsHm66CSWKg:398:21:Bil Lewis:/user/lewis:/bin/csh | |
304 | ||
305 | ---------- Buffer: bar ---------- | |
306 | @end group | |
307 | @end smallexample | |
308 | ||
969fe9b5 RS |
309 | Here is a good example of the use of @code{call-process}, which used to |
310 | be found in the definition of @code{insert-directory}: | |
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311 | |
312 | @smallexample | |
313 | @group | |
969fe9b5 | 314 | (call-process insert-directory-program nil t nil @var{switches} |
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315 | (if full-directory-p |
316 | (concat (file-name-as-directory file) ".") | |
317 | file)) | |
318 | @end group | |
319 | @end smallexample | |
320 | @end defun | |
321 | ||
bb5d6d34 KG |
322 | @defun process-file program &optional infile buffer display &rest args |
323 | This function processes files synchronously in a separate process. It | |
324 | is similar to @code{call-process} but may invoke a file handler based | |
325 | on the value of the variable @code{default-directory}. The current | |
326 | working directory of the subprocess is @code{default-directory}. | |
327 | ||
328 | The arguments are handled in almost the same way as for | |
329 | @code{call-process}, with the following differences: | |
330 | ||
331 | Some file handlers may not support all combinations and forms of the | |
332 | arguments @var{infile}, @var{buffer}, and @var{display}. For example, | |
f8684c07 | 333 | some file handlers might behave as if @var{display} were @code{nil}, |
bb5d6d34 KG |
334 | regardless of the value actually passed. As another example, some |
335 | file handlers might not support separating standard output and error | |
336 | output by way of the @var{buffer} argument. | |
337 | ||
338 | If a file handler is invoked, it determines the program to run based | |
339 | on the first argument @var{program}. For instance, consider that a | |
340 | handler for remote files is invoked. Then the path that is used for | |
341 | searching the program might be different than @code{exec-path}. | |
342 | ||
343 | The second argument @var{infile} may invoke a file handler. The file | |
344 | handler could be different from the handler chosen for the | |
345 | @code{process-file} function itself. (For example, | |
346 | @code{default-directory} could be on a remote host, whereas | |
347 | @var{infile} is on another remote host. Or @code{default-directory} | |
348 | could be non-special, whereas @var{infile} is on a remote host.) | |
349 | ||
350 | If @var{buffer} has the form @code{(@var{real-destination} | |
351 | @var{error-destination})}, and @var{error-destination} names a file, | |
352 | then the same remarks as for @var{infile} apply. | |
353 | ||
354 | The remaining arguments (@var{args}) will be passed to the process | |
355 | verbatim. Emacs is not involved in processing file names that are | |
356 | present in @var{args}. To avoid confusion, it may be best to avoid | |
357 | absolute file names in @var{args}, but rather to specify all file | |
358 | names as relative to @code{default-directory}. The function | |
359 | @code{file-relative-name} is useful for constructing such relative | |
360 | file names. | |
361 | @end defun | |
362 | ||
22697dac | 363 | @defun call-process-region start end program &optional delete destination display &rest args |
8241495d | 364 | This function sends the text from @var{start} to @var{end} as |
73804d4b | 365 | standard input to a process running @var{program}. It deletes the text |
f9f59935 RS |
366 | sent if @var{delete} is non-@code{nil}; this is useful when |
367 | @var{destination} is @code{t}, to insert the output in the current | |
368 | buffer in place of the input. | |
73804d4b | 369 | |
22697dac | 370 | The arguments @var{destination} and @var{display} control what to do |
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371 | with the output from the subprocess, and whether to update the display |
372 | as it comes in. For details, see the description of | |
22697dac | 373 | @code{call-process}, above. If @var{destination} is the integer 0, |
73804d4b | 374 | @code{call-process-region} discards the output and returns @code{nil} |
8241495d | 375 | immediately, without waiting for the subprocess to finish (this only |
4f939ab8 | 376 | works if asynchronous subprocesses are supported). |
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377 | |
378 | The remaining arguments, @var{args}, are strings that specify command | |
379 | line arguments for the program. | |
380 | ||
381 | The return value of @code{call-process-region} is just like that of | |
382 | @code{call-process}: @code{nil} if you told it to return without | |
383 | waiting; otherwise, a number or string which indicates how the | |
384 | subprocess terminated. | |
385 | ||
386 | In the following example, we use @code{call-process-region} to run the | |
387 | @code{cat} utility, with standard input being the first five characters | |
388 | in buffer @samp{foo} (the word @samp{input}). @code{cat} copies its | |
389 | standard input into its standard output. Since the argument | |
22697dac | 390 | @var{destination} is @code{t}, this output is inserted in the current |
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391 | buffer. |
392 | ||
393 | @smallexample | |
394 | @group | |
395 | ---------- Buffer: foo ---------- | |
396 | input@point{} | |
397 | ---------- Buffer: foo ---------- | |
398 | @end group | |
399 | ||
400 | @group | |
401 | (call-process-region 1 6 "cat" nil t) | |
8241495d | 402 | @result{} 0 |
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403 | |
404 | ---------- Buffer: foo ---------- | |
405 | inputinput@point{} | |
406 | ---------- Buffer: foo ---------- | |
407 | @end group | |
408 | @end smallexample | |
409 | ||
410 | The @code{shell-command-on-region} command uses | |
411 | @code{call-process-region} like this: | |
412 | ||
413 | @smallexample | |
414 | @group | |
177c0ea7 JB |
415 | (call-process-region |
416 | start end | |
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417 | shell-file-name ; @r{Name of program.} |
418 | nil ; @r{Do not delete region.} | |
419 | buffer ; @r{Send output to @code{buffer}.} | |
420 | nil ; @r{No redisplay during output.} | |
421 | "-c" command) ; @r{Arguments for the shell.} | |
422 | @end group | |
423 | @end smallexample | |
424 | @end defun | |
425 | ||
4bb24054 RS |
426 | @defun call-process-shell-command command &optional infile destination display &rest args |
427 | This function executes the shell command @var{command} synchronously | |
38e82e48 | 428 | in a separate process. The final arguments @var{args} are additional |
4bb24054 RS |
429 | arguments to add at the end of @var{command}. The other arguments |
430 | are handled as in @code{call-process}. | |
431 | @end defun | |
432 | ||
f9f59935 RS |
433 | @defun shell-command-to-string command |
434 | This function executes @var{command} (a string) as a shell command, | |
435 | then returns the command's output as a string. | |
436 | @end defun | |
437 | ||
73804d4b RS |
438 | @node Asynchronous Processes |
439 | @section Creating an Asynchronous Process | |
440 | @cindex asynchronous subprocess | |
441 | ||
1911e6e5 RS |
442 | After an @dfn{asynchronous process} is created, Emacs and the subprocess |
443 | both continue running immediately. The process thereafter runs | |
a9f0a989 | 444 | in parallel with Emacs, and the two can communicate with each other |
8241495d | 445 | using the functions described in the following sections. However, |
a9f0a989 RS |
446 | communication is only partially asynchronous: Emacs sends data to the |
447 | process only when certain functions are called, and Emacs accepts data | |
448 | from the process only when Emacs is waiting for input or for a time | |
449 | delay. | |
450 | ||
451 | Here we describe how to create an asynchronous process. | |
73804d4b RS |
452 | |
453 | @defun start-process name buffer-or-name program &rest args | |
454 | This function creates a new asynchronous subprocess and starts the | |
455 | program @var{program} running in it. It returns a process object that | |
456 | stands for the new subprocess in Lisp. The argument @var{name} | |
457 | specifies the name for the process object; if a process with this name | |
f9f59935 RS |
458 | already exists, then @var{name} is modified (by appending @samp{<1>}, |
459 | etc.) to be unique. The buffer @var{buffer-or-name} is the buffer to | |
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460 | associate with the process. |
461 | ||
462 | The remaining arguments, @var{args}, are strings that specify command | |
463 | line arguments for the program. | |
464 | ||
465 | In the example below, the first process is started and runs (rather, | |
466 | sleeps) for 100 seconds. Meanwhile, the second process is started, and | |
467 | given the name @samp{my-process<1>} for the sake of uniqueness. It | |
468 | inserts the directory listing at the end of the buffer @samp{foo}, | |
469 | before the first process finishes. Then it finishes, and a message to | |
470 | that effect is inserted in the buffer. Much later, the first process | |
471 | finishes, and another message is inserted in the buffer for it. | |
472 | ||
473 | @smallexample | |
474 | @group | |
475 | (start-process "my-process" "foo" "sleep" "100") | |
476 | @result{} #<process my-process> | |
477 | @end group | |
478 | ||
479 | @group | |
480 | (start-process "my-process" "foo" "ls" "-l" "/user/lewis/bin") | |
481 | @result{} #<process my-process<1>> | |
482 | ||
483 | ---------- Buffer: foo ---------- | |
484 | total 2 | |
485 | lrwxrwxrwx 1 lewis 14 Jul 22 10:12 gnuemacs --> /emacs | |
486 | -rwxrwxrwx 1 lewis 19 Jul 30 21:02 lemon | |
487 | ||
488 | Process my-process<1> finished | |
489 | ||
490 | Process my-process finished | |
491 | ---------- Buffer: foo ---------- | |
492 | @end group | |
493 | @end smallexample | |
494 | @end defun | |
495 | ||
496 | @defun start-process-shell-command name buffer-or-name command &rest command-args | |
497 | This function is like @code{start-process} except that it uses a shell | |
498 | to execute the specified command. The argument @var{command} is a shell | |
499 | command name, and @var{command-args} are the arguments for the shell | |
f9f59935 RS |
500 | command. The variable @code{shell-file-name} specifies which shell to |
501 | use. | |
969fe9b5 RS |
502 | |
503 | The point of running a program through the shell, rather than directly | |
504 | with @code{start-process}, is so that you can employ shell features such | |
505 | as wildcards in the arguments. It follows that if you include an | |
8241495d | 506 | arbitrary user-specified arguments in the command, you should quote it |
969fe9b5 | 507 | with @code{shell-quote-argument} first, so that any special shell |
8241495d RS |
508 | characters do @emph{not} have their special shell meanings. @xref{Shell |
509 | Arguments}. | |
73804d4b RS |
510 | @end defun |
511 | ||
512 | @defvar process-connection-type | |
513 | @cindex pipes | |
ad800164 | 514 | @cindex @acronym{PTY}s |
73804d4b | 515 | This variable controls the type of device used to communicate with |
ad800164 | 516 | asynchronous subprocesses. If it is non-@code{nil}, then @acronym{PTY}s are |
bfe721d1 | 517 | used, when available. Otherwise, pipes are used. |
73804d4b | 518 | |
ad800164 | 519 | @acronym{PTY}s are usually preferable for processes visible to the user, as |
73804d4b | 520 | in Shell mode, because they allow job control (@kbd{C-c}, @kbd{C-z}, |
f9f59935 RS |
521 | etc.) to work between the process and its children, whereas pipes do |
522 | not. For subprocesses used for internal purposes by programs, it is | |
523 | often better to use a pipe, because they are more efficient. In | |
ad800164 | 524 | addition, the total number of @acronym{PTY}s is limited on many systems and |
f9f59935 | 525 | it is good not to waste them. |
73804d4b | 526 | |
edc590bb | 527 | The value of @code{process-connection-type} takes effect when |
73804d4b RS |
528 | @code{start-process} is called. So you can specify how to communicate |
529 | with one subprocess by binding the variable around the call to | |
530 | @code{start-process}. | |
531 | ||
532 | @smallexample | |
533 | @group | |
534 | (let ((process-connection-type nil)) ; @r{Use a pipe.} | |
535 | (start-process @dots{})) | |
536 | @end group | |
537 | @end smallexample | |
22697dac KH |
538 | |
539 | To determine whether a given subprocess actually got a pipe or a | |
ad800164 | 540 | @acronym{PTY}, use the function @code{process-tty-name} (@pxref{Process |
22697dac | 541 | Information}). |
73804d4b RS |
542 | @end defvar |
543 | ||
544 | @node Deleting Processes | |
545 | @section Deleting Processes | |
546 | @cindex deleting processes | |
547 | ||
548 | @dfn{Deleting a process} disconnects Emacs immediately from the | |
5517ea8a RS |
549 | subprocess. Processes are deleted automatically after they terminate, |
550 | but not necessarily right away. You can delete a process explicitly | |
551 | at any time. If you delete a terminated process explicitly before it | |
fea5a6d5 | 552 | is deleted automatically, no harm results. Deleting a running |
edc590bb | 553 | process sends a signal to terminate it (and its child processes if |
fea5a6d5 | 554 | any), and calls the process sentinel if it has one. @xref{Sentinels}. |
5517ea8a | 555 | |
fea5a6d5 RS |
556 | When a process is deleted, the process object itself continues to |
557 | exist as long as other Lisp objects point to it. All the Lisp | |
558 | primitives that work on process objects accept deleted processes, but | |
559 | those that do I/O or send signals will report an error. The process | |
560 | mark continues to point to the same place as before, usually into a | |
561 | buffer where output from the process was being inserted. | |
73804d4b | 562 | |
1911e6e5 | 563 | @defopt delete-exited-processes |
73804d4b RS |
564 | This variable controls automatic deletion of processes that have |
565 | terminated (due to calling @code{exit} or to a signal). If it is | |
566 | @code{nil}, then they continue to exist until the user runs | |
567 | @code{list-processes}. Otherwise, they are deleted immediately after | |
568 | they exit. | |
1911e6e5 | 569 | @end defopt |
73804d4b | 570 | |
fea5a6d5 RS |
571 | @defun delete-process process |
572 | This function deletes a process, killing it with a @code{SIGKILL} | |
573 | signal. The argument may be a process, the name of a process, a | |
574 | buffer, or the name of a buffer. (A buffer or buffer-name stands for | |
575 | the process that @code{get-buffer-process} returns.) Calling | |
576 | @code{delete-process} on a running process terminates it, updates the | |
577 | process status, and runs the sentinel (if any) immediately. If the | |
578 | process has already terminated, calling @code{delete-process} has no | |
579 | effect on its status, or on the running of its sentinel (which will | |
580 | happen sooner or later). | |
73804d4b RS |
581 | |
582 | @smallexample | |
583 | @group | |
584 | (delete-process "*shell*") | |
585 | @result{} nil | |
586 | @end group | |
587 | @end smallexample | |
588 | @end defun | |
589 | ||
73804d4b RS |
590 | @node Process Information |
591 | @section Process Information | |
592 | ||
593 | Several functions return information about processes. | |
594 | @code{list-processes} is provided for interactive use. | |
595 | ||
4bb24054 | 596 | @deffn Command list-processes &optional query-only |
73804d4b RS |
597 | This command displays a listing of all living processes. In addition, |
598 | it finally deletes any process whose status was @samp{Exited} or | |
599 | @samp{Signaled}. It returns @code{nil}. | |
4bb24054 RS |
600 | |
601 | If @var{query-only} is non-@code{nil} then it lists only processes | |
602 | whose query flag is non-@code{nil}. @xref{Query Before Exit}. | |
73804d4b RS |
603 | @end deffn |
604 | ||
605 | @defun process-list | |
606 | This function returns a list of all processes that have not been deleted. | |
607 | ||
608 | @smallexample | |
609 | @group | |
610 | (process-list) | |
611 | @result{} (#<process display-time> #<process shell>) | |
612 | @end group | |
613 | @end smallexample | |
614 | @end defun | |
615 | ||
616 | @defun get-process name | |
617 | This function returns the process named @var{name}, or @code{nil} if | |
618 | there is none. An error is signaled if @var{name} is not a string. | |
619 | ||
620 | @smallexample | |
621 | @group | |
622 | (get-process "shell") | |
623 | @result{} #<process shell> | |
624 | @end group | |
625 | @end smallexample | |
626 | @end defun | |
627 | ||
628 | @defun process-command process | |
629 | This function returns the command that was executed to start | |
630 | @var{process}. This is a list of strings, the first string being the | |
631 | program executed and the rest of the strings being the arguments that | |
632 | were given to the program. | |
633 | ||
634 | @smallexample | |
635 | @group | |
636 | (process-command (get-process "shell")) | |
637 | @result{} ("/bin/csh" "-i") | |
638 | @end group | |
639 | @end smallexample | |
640 | @end defun | |
641 | ||
642 | @defun process-id process | |
ad800164 | 643 | This function returns the @acronym{PID} of @var{process}. This is an |
78608595 | 644 | integer that distinguishes the process @var{process} from all other |
73804d4b | 645 | processes running on the same computer at the current time. The |
ad800164 | 646 | @acronym{PID} of a process is chosen by the operating system kernel when the |
73804d4b RS |
647 | process is started and remains constant as long as the process exists. |
648 | @end defun | |
649 | ||
650 | @defun process-name process | |
651 | This function returns the name of @var{process}. | |
652 | @end defun | |
653 | ||
654 | @defun process-status process-name | |
655 | This function returns the status of @var{process-name} as a symbol. | |
656 | The argument @var{process-name} must be a process, a buffer, a | |
657 | process name (string) or a buffer name (string). | |
658 | ||
659 | The possible values for an actual subprocess are: | |
660 | ||
661 | @table @code | |
662 | @item run | |
663 | for a process that is running. | |
664 | @item stop | |
665 | for a process that is stopped but continuable. | |
666 | @item exit | |
667 | for a process that has exited. | |
668 | @item signal | |
669 | for a process that has received a fatal signal. | |
670 | @item open | |
671 | for a network connection that is open. | |
672 | @item closed | |
673 | for a network connection that is closed. Once a connection | |
674 | is closed, you cannot reopen it, though you might be able to open | |
675 | a new connection to the same place. | |
4bb24054 RS |
676 | @item connect |
677 | for a non-blocking connection that is waiting to complete. | |
678 | @item failed | |
679 | for a non-blocking connection that has failed to complete. | |
680 | @item listen | |
681 | for a network server that is listening. | |
73804d4b RS |
682 | @item nil |
683 | if @var{process-name} is not the name of an existing process. | |
684 | @end table | |
685 | ||
686 | @smallexample | |
687 | @group | |
688 | (process-status "shell") | |
689 | @result{} run | |
690 | @end group | |
691 | @group | |
692 | (process-status (get-buffer "*shell*")) | |
693 | @result{} run | |
694 | @end group | |
695 | @group | |
696 | x | |
697 | @result{} #<process xx<1>> | |
698 | (process-status x) | |
699 | @result{} exit | |
700 | @end group | |
701 | @end smallexample | |
702 | ||
703 | For a network connection, @code{process-status} returns one of the symbols | |
704 | @code{open} or @code{closed}. The latter means that the other side | |
705 | closed the connection, or Emacs did @code{delete-process}. | |
73804d4b RS |
706 | @end defun |
707 | ||
708 | @defun process-exit-status process | |
709 | This function returns the exit status of @var{process} or the signal | |
710 | number that killed it. (Use the result of @code{process-status} to | |
711 | determine which of those it is.) If @var{process} has not yet | |
712 | terminated, the value is 0. | |
713 | @end defun | |
714 | ||
22697dac KH |
715 | @defun process-tty-name process |
716 | This function returns the terminal name that @var{process} is using for | |
717 | its communication with Emacs---or @code{nil} if it is using pipes | |
718 | instead of a terminal (see @code{process-connection-type} in | |
719 | @ref{Asynchronous Processes}). | |
720 | @end defun | |
721 | ||
f9f59935 | 722 | @defun process-coding-system process |
7baeca0c | 723 | @anchor{Coding systems for a subprocess} |
f9f59935 RS |
724 | This function returns a cons cell describing the coding systems in use |
725 | for decoding output from @var{process} and for encoding input to | |
726 | @var{process} (@pxref{Coding Systems}). The value has this form: | |
727 | ||
728 | @example | |
969fe9b5 | 729 | (@var{coding-system-for-decoding} . @var{coding-system-for-encoding}) |
f9f59935 RS |
730 | @end example |
731 | @end defun | |
732 | ||
fea5a6d5 | 733 | @defun set-process-coding-system process &optional decoding-system encoding-system |
f9f59935 RS |
734 | This function specifies the coding systems to use for subsequent output |
735 | from and input to @var{process}. It will use @var{decoding-system} to | |
736 | decode subprocess output, and @var{encoding-system} to encode subprocess | |
737 | input. | |
4bb24054 RS |
738 | @end defun |
739 | ||
740 | Every process also has a property list that you can use to store | |
741 | miscellaneous values associated with the process. | |
742 | ||
743 | @defun process-get process propname | |
744 | This function returns the value of the @var{propname} property | |
745 | of @var{process}. | |
746 | @end defun | |
747 | ||
748 | @defun process-put process propname value | |
749 | This function sets the value of the @var{propname} property | |
750 | of @var{process} to @var{value}. | |
751 | @end defun | |
752 | ||
753 | @defun process-plist process | |
754 | This function returns the process plist of @var{process}. | |
755 | @end defun | |
756 | ||
757 | @defun set-process-plist process plist | |
758 | This function sets the process plist of @var{process} to @var{plist}. | |
f9f59935 RS |
759 | @end defun |
760 | ||
73804d4b RS |
761 | @node Input to Processes |
762 | @section Sending Input to Processes | |
763 | @cindex process input | |
764 | ||
765 | Asynchronous subprocesses receive input when it is sent to them by | |
766 | Emacs, which is done with the functions in this section. You must | |
767 | specify the process to send input to, and the input data to send. The | |
768 | data appears on the ``standard input'' of the subprocess. | |
769 | ||
770 | Some operating systems have limited space for buffered input in a | |
3f7fab24 LT |
771 | @acronym{PTY}. On these systems, Emacs sends an @acronym{EOF} |
772 | periodically amidst the other characters, to force them through. For | |
773 | most programs, these @acronym{EOF}s do no harm. | |
73804d4b | 774 | |
f9f59935 | 775 | Subprocess input is normally encoded using a coding system before the |
a9f0a989 RS |
776 | subprocess receives it, much like text written into a file. You can use |
777 | @code{set-process-coding-system} to specify which coding system to use | |
778 | (@pxref{Process Information}). Otherwise, the coding system comes from | |
779 | @code{coding-system-for-write}, if that is non-@code{nil}; or else from | |
780 | the defaulting mechanism (@pxref{Default Coding Systems}). | |
f9f59935 | 781 | |
b6954afd RS |
782 | Sometimes the system is unable to accept input for that process, |
783 | because the input buffer is full. When this happens, the send functions | |
784 | wait a short while, accepting output from subprocesses, and then try | |
785 | again. This gives the subprocess a chance to read more of its pending | |
786 | input and make space in the buffer. It also allows filters, sentinels | |
787 | and timers to run---so take account of that in writing your code. | |
788 | ||
fea5a6d5 RS |
789 | In these functions, the @var{process} argument can be a process or |
790 | the name of a process, or a buffer or buffer name (which stands | |
791 | for a process via @code{get-buffer-process}). @code{nil} means | |
792 | the current buffer's process. | |
793 | ||
794 | @defun process-send-string process string | |
795 | This function sends @var{process} the contents of @var{string} as | |
796 | standard input. If it is @code{nil}, the current buffer's process is used. | |
73804d4b RS |
797 | |
798 | The function returns @code{nil}. | |
799 | ||
800 | @smallexample | |
801 | @group | |
802 | (process-send-string "shell<1>" "ls\n") | |
803 | @result{} nil | |
804 | @end group | |
805 | ||
806 | ||
807 | @group | |
808 | ---------- Buffer: *shell* ---------- | |
809 | ... | |
810 | introduction.texi syntax-tables.texi~ | |
811 | introduction.texi~ text.texi | |
812 | introduction.txt text.texi~ | |
813 | ... | |
814 | ---------- Buffer: *shell* ---------- | |
815 | @end group | |
816 | @end smallexample | |
817 | @end defun | |
818 | ||
fea5a6d5 | 819 | @defun process-send-region process start end |
73804d4b | 820 | This function sends the text in the region defined by @var{start} and |
fea5a6d5 | 821 | @var{end} as standard input to @var{process}. |
73804d4b RS |
822 | |
823 | An error is signaled unless both @var{start} and @var{end} are | |
824 | integers or markers that indicate positions in the current buffer. (It | |
825 | is unimportant which number is larger.) | |
8241495d | 826 | @end defun |
73804d4b | 827 | |
fea5a6d5 RS |
828 | @defun process-send-eof &optional process |
829 | This function makes @var{process} see an end-of-file in its | |
ad800164 | 830 | input. The @acronym{EOF} comes after any text already sent to it. |
73804d4b | 831 | |
fea5a6d5 | 832 | The function returns @var{process}. |
73804d4b RS |
833 | |
834 | @smallexample | |
835 | @group | |
836 | (process-send-eof "shell") | |
837 | @result{} "shell" | |
838 | @end group | |
839 | @end smallexample | |
840 | @end defun | |
841 | ||
b6954afd RS |
842 | @defun process-running-child-p process |
843 | @tindex process-running-child-p process | |
844 | This function will tell you whether a subprocess has given control of | |
845 | its terminal to its own child process. The value is @code{t} if this is | |
846 | true, or if Emacs cannot tell; it is @code{nil} if Emacs can be certain | |
847 | that this is not so. | |
848 | @end defun | |
849 | ||
73804d4b RS |
850 | @node Signals to Processes |
851 | @section Sending Signals to Processes | |
852 | @cindex process signals | |
853 | @cindex sending signals | |
854 | @cindex signals | |
855 | ||
856 | @dfn{Sending a signal} to a subprocess is a way of interrupting its | |
857 | activities. There are several different signals, each with its own | |
858 | meaning. The set of signals and their names is defined by the operating | |
859 | system. For example, the signal @code{SIGINT} means that the user has | |
860 | typed @kbd{C-c}, or that some analogous thing has happened. | |
861 | ||
862 | Each signal has a standard effect on the subprocess. Most signals | |
863 | kill the subprocess, but some stop or resume execution instead. Most | |
864 | signals can optionally be handled by programs; if the program handles | |
865 | the signal, then we can say nothing in general about its effects. | |
866 | ||
867 | You can send signals explicitly by calling the functions in this | |
868 | section. Emacs also sends signals automatically at certain times: | |
869 | killing a buffer sends a @code{SIGHUP} signal to all its associated | |
870 | processes; killing Emacs sends a @code{SIGHUP} signal to all remaining | |
871 | processes. (@code{SIGHUP} is a signal that usually indicates that the | |
872 | user hung up the phone.) | |
873 | ||
874 | Each of the signal-sending functions takes two optional arguments: | |
f91aa2aa | 875 | @var{process} and @var{current-group}. |
73804d4b | 876 | |
fea5a6d5 RS |
877 | The argument @var{process} must be either a process, a process |
878 | name, a buffer, a buffer name, or @code{nil}. A buffer or buffer name | |
879 | stands for a process through @code{get-buffer-process}. @code{nil} | |
880 | stands for the process associated with the current buffer. An error | |
881 | is signaled if @var{process} does not identify a process. | |
73804d4b RS |
882 | |
883 | The argument @var{current-group} is a flag that makes a difference | |
884 | when you are running a job-control shell as an Emacs subprocess. If it | |
885 | is non-@code{nil}, then the signal is sent to the current process-group | |
78608595 | 886 | of the terminal that Emacs uses to communicate with the subprocess. If |
73804d4b RS |
887 | the process is a job-control shell, this means the shell's current |
888 | subjob. If it is @code{nil}, the signal is sent to the process group of | |
889 | the immediate subprocess of Emacs. If the subprocess is a job-control | |
890 | shell, this is the shell itself. | |
891 | ||
892 | The flag @var{current-group} has no effect when a pipe is used to | |
893 | communicate with the subprocess, because the operating system does not | |
894 | support the distinction in the case of pipes. For the same reason, | |
895 | job-control shells won't work when a pipe is used. See | |
896 | @code{process-connection-type} in @ref{Asynchronous Processes}. | |
897 | ||
fea5a6d5 RS |
898 | @defun interrupt-process &optional process current-group |
899 | This function interrupts the process @var{process} by sending the | |
73804d4b RS |
900 | signal @code{SIGINT}. Outside of Emacs, typing the ``interrupt |
901 | character'' (normally @kbd{C-c} on some systems, and @code{DEL} on | |
902 | others) sends this signal. When the argument @var{current-group} is | |
903 | non-@code{nil}, you can think of this function as ``typing @kbd{C-c}'' | |
904 | on the terminal by which Emacs talks to the subprocess. | |
905 | @end defun | |
906 | ||
fea5a6d5 RS |
907 | @defun kill-process &optional process current-group |
908 | This function kills the process @var{process} by sending the | |
73804d4b RS |
909 | signal @code{SIGKILL}. This signal kills the subprocess immediately, |
910 | and cannot be handled by the subprocess. | |
911 | @end defun | |
912 | ||
fea5a6d5 | 913 | @defun quit-process &optional process current-group |
73804d4b | 914 | This function sends the signal @code{SIGQUIT} to the process |
fea5a6d5 | 915 | @var{process}. This signal is the one sent by the ``quit |
73804d4b RS |
916 | character'' (usually @kbd{C-b} or @kbd{C-\}) when you are not inside |
917 | Emacs. | |
918 | @end defun | |
919 | ||
fea5a6d5 RS |
920 | @defun stop-process &optional process current-group |
921 | This function stops the process @var{process} by sending the | |
73804d4b RS |
922 | signal @code{SIGTSTP}. Use @code{continue-process} to resume its |
923 | execution. | |
924 | ||
969fe9b5 | 925 | Outside of Emacs, on systems with job control, the ``stop character'' |
f9f59935 RS |
926 | (usually @kbd{C-z}) normally sends this signal. When |
927 | @var{current-group} is non-@code{nil}, you can think of this function as | |
928 | ``typing @kbd{C-z}'' on the terminal Emacs uses to communicate with the | |
929 | subprocess. | |
73804d4b RS |
930 | @end defun |
931 | ||
fea5a6d5 | 932 | @defun continue-process &optional process current-group |
73804d4b | 933 | This function resumes execution of the process @var{process} by sending |
fea5a6d5 | 934 | it the signal @code{SIGCONT}. This presumes that @var{process} was |
73804d4b RS |
935 | stopped previously. |
936 | @end defun | |
937 | ||
938 | @c Emacs 19 feature | |
4bb24054 RS |
939 | @defun signal-process process signal |
940 | This function sends a signal to process @var{process}. The argument | |
941 | @var{signal} specifies which signal to send; it should be an integer. | |
942 | ||
fea5a6d5 RS |
943 | The @var{process} argument can be a system process @acronym{ID}; that |
944 | allows you to send signals to processes that are not children of | |
945 | Emacs. | |
73804d4b RS |
946 | @end defun |
947 | ||
948 | @node Output from Processes | |
949 | @section Receiving Output from Processes | |
950 | @cindex process output | |
951 | @cindex output from processes | |
952 | ||
953 | There are two ways to receive the output that a subprocess writes to | |
954 | its standard output stream. The output can be inserted in a buffer, | |
955 | which is called the associated buffer of the process, or a function | |
78608595 RS |
956 | called the @dfn{filter function} can be called to act on the output. If |
957 | the process has no buffer and no filter function, its output is | |
958 | discarded. | |
177c0ea7 | 959 | |
edc590bb RS |
960 | When a subprocess terminates, Emacs reads any pending output, |
961 | then stops reading output from that subprocess. Therefore, if the | |
962 | subprocess has children that are still live and still producing | |
963 | output, Emacs won't receive that output. | |
964 | ||
a9f0a989 RS |
965 | Output from a subprocess can arrive only while Emacs is waiting: when |
966 | reading terminal input, in @code{sit-for} and @code{sleep-for} | |
967 | (@pxref{Waiting}), and in @code{accept-process-output} (@pxref{Accepting | |
968 | Output}). This minimizes the problem of timing errors that usually | |
969 | plague parallel programming. For example, you can safely create a | |
970 | process and only then specify its buffer or filter function; no output | |
971 | can arrive before you finish, if the code in between does not call any | |
972 | primitive that waits. | |
973 | ||
bfa96fa2 KS |
974 | @defvar process-adaptive-read-buffering |
975 | On some systems, when Emacs reads the output from a subprocess, the | |
976 | output data is read in very small blocks, potentially resulting in | |
3f7fab24 | 977 | very poor performance. This behavior can be remedied to some extent |
bfa96fa2 | 978 | by setting the variable @var{process-adaptive-read-buffering} to a |
c1aa4864 | 979 | non-@code{nil} value (the default), as it will automatically delay reading |
bfa96fa2 KS |
980 | from such processes, thus allowing them to produce more output before |
981 | Emacs tries to read it. | |
982 | @end defvar | |
983 | ||
8f3efb4e RS |
984 | It is impossible to separate the standard output and standard error |
985 | streams of the subprocess, because Emacs normally spawns the subprocess | |
986 | inside a pseudo-TTY, and a pseudo-TTY has only one output channel. If | |
987 | you want to keep the output to those streams separate, you should | |
4810d170 | 988 | redirect one of them to a file---for example, by using an appropriate |
8f3efb4e RS |
989 | shell command. |
990 | ||
73804d4b | 991 | @menu |
582ef186 RS |
992 | * Process Buffers:: If no filter, output is put in a buffer. |
993 | * Filter Functions:: Filter functions accept output from the process. | |
591a3500 | 994 | * Decoding Output:: Filters can get unibyte or multibyte strings. |
582ef186 | 995 | * Accepting Output:: How to wait until process output arrives. |
73804d4b RS |
996 | @end menu |
997 | ||
998 | @node Process Buffers | |
999 | @subsection Process Buffers | |
1000 | ||
1001 | A process can (and usually does) have an @dfn{associated buffer}, | |
1002 | which is an ordinary Emacs buffer that is used for two purposes: storing | |
1003 | the output from the process, and deciding when to kill the process. You | |
1004 | can also use the buffer to identify a process to operate on, since in | |
1005 | normal practice only one process is associated with any given buffer. | |
1006 | Many applications of processes also use the buffer for editing input to | |
1007 | be sent to the process, but this is not built into Emacs Lisp. | |
1008 | ||
1009 | Unless the process has a filter function (@pxref{Filter Functions}), | |
1010 | its output is inserted in the associated buffer. The position to insert | |
78608595 RS |
1011 | the output is determined by the @code{process-mark}, which is then |
1012 | updated to point to the end of the text just inserted. Usually, but not | |
1013 | always, the @code{process-mark} is at the end of the buffer. | |
73804d4b RS |
1014 | |
1015 | @defun process-buffer process | |
1016 | This function returns the associated buffer of the process | |
1017 | @var{process}. | |
1018 | ||
1019 | @smallexample | |
1020 | @group | |
1021 | (process-buffer (get-process "shell")) | |
1022 | @result{} #<buffer *shell*> | |
1023 | @end group | |
1024 | @end smallexample | |
1025 | @end defun | |
1026 | ||
1027 | @defun process-mark process | |
1028 | This function returns the process marker for @var{process}, which is the | |
1029 | marker that says where to insert output from the process. | |
1030 | ||
1031 | If @var{process} does not have a buffer, @code{process-mark} returns a | |
1032 | marker that points nowhere. | |
1033 | ||
1034 | Insertion of process output in a buffer uses this marker to decide where | |
1035 | to insert, and updates it to point after the inserted text. That is why | |
1036 | successive batches of output are inserted consecutively. | |
1037 | ||
1038 | Filter functions normally should use this marker in the same fashion | |
1039 | as is done by direct insertion of output in the buffer. A good | |
1040 | example of a filter function that uses @code{process-mark} is found at | |
1041 | the end of the following section. | |
1042 | ||
1043 | When the user is expected to enter input in the process buffer for | |
f9f59935 RS |
1044 | transmission to the process, the process marker separates the new input |
1045 | from previous output. | |
73804d4b RS |
1046 | @end defun |
1047 | ||
1048 | @defun set-process-buffer process buffer | |
1049 | This function sets the buffer associated with @var{process} to | |
1050 | @var{buffer}. If @var{buffer} is @code{nil}, the process becomes | |
1051 | associated with no buffer. | |
1052 | @end defun | |
1053 | ||
1054 | @defun get-buffer-process buffer-or-name | |
5517ea8a RS |
1055 | This function returns a nondeleted process associated with the buffer |
1056 | specified by @var{buffer-or-name}. If there are several processes | |
1057 | associated with it, this function chooses one (currently, the one most | |
1058 | recently created, but don't count on that). Deletion of a process | |
1059 | (see @code{delete-process}) makes it ineligible for this function to | |
1060 | return. | |
1061 | ||
1062 | It is usually a bad idea to have more than one process associated with | |
1063 | the same buffer. | |
73804d4b RS |
1064 | |
1065 | @smallexample | |
1066 | @group | |
1067 | (get-buffer-process "*shell*") | |
1068 | @result{} #<process shell> | |
1069 | @end group | |
1070 | @end smallexample | |
1071 | ||
1072 | Killing the process's buffer deletes the process, which kills the | |
1073 | subprocess with a @code{SIGHUP} signal (@pxref{Signals to Processes}). | |
1074 | @end defun | |
1075 | ||
1076 | @node Filter Functions | |
1077 | @subsection Process Filter Functions | |
1078 | @cindex filter function | |
1079 | @cindex process filter | |
1080 | ||
1081 | A process @dfn{filter function} is a function that receives the | |
1082 | standard output from the associated process. If a process has a filter, | |
78608595 RS |
1083 | then @emph{all} output from that process is passed to the filter. The |
1084 | process buffer is used directly for output from the process only when | |
1085 | there is no filter. | |
73804d4b | 1086 | |
a9f0a989 RS |
1087 | The filter function can only be called when Emacs is waiting for |
1088 | something, because process output arrives only at such times. Emacs | |
1089 | waits when reading terminal input, in @code{sit-for} and | |
1090 | @code{sleep-for} (@pxref{Waiting}), and in @code{accept-process-output} | |
1091 | (@pxref{Accepting Output}). | |
1092 | ||
f9f59935 RS |
1093 | A filter function must accept two arguments: the associated process |
1094 | and a string, which is output just received from it. The function is | |
1095 | then free to do whatever it chooses with the output. | |
73804d4b | 1096 | |
73804d4b RS |
1097 | Quitting is normally inhibited within a filter function---otherwise, |
1098 | the effect of typing @kbd{C-g} at command level or to quit a user | |
75c0692f RS |
1099 | command would be unpredictable. If you want to permit quitting inside |
1100 | a filter function, bind @code{inhibit-quit} to @code{nil}. In most | |
1101 | cases, the right way to do this is with the macro | |
1102 | @code{with-local-quit}. @xref{Quitting}. | |
73804d4b | 1103 | |
22697dac KH |
1104 | If an error happens during execution of a filter function, it is |
1105 | caught automatically, so that it doesn't stop the execution of whatever | |
eaac2be1 | 1106 | program was running when the filter function was started. However, if |
22697dac KH |
1107 | @code{debug-on-error} is non-@code{nil}, the error-catching is turned |
1108 | off. This makes it possible to use the Lisp debugger to debug the | |
1109 | filter function. @xref{Debugger}. | |
1110 | ||
73804d4b RS |
1111 | Many filter functions sometimes or always insert the text in the |
1112 | process's buffer, mimicking the actions of Emacs when there is no | |
1113 | filter. Such filter functions need to use @code{set-buffer} in order to | |
1114 | be sure to insert in that buffer. To avoid setting the current buffer | |
f9f59935 RS |
1115 | semipermanently, these filter functions must save and restore the |
1116 | current buffer. They should also update the process marker, and in some | |
1117 | cases update the value of point. Here is how to do these things: | |
73804d4b RS |
1118 | |
1119 | @smallexample | |
1120 | @group | |
1121 | (defun ordinary-insertion-filter (proc string) | |
f9f59935 RS |
1122 | (with-current-buffer (process-buffer proc) |
1123 | (let ((moving (= (point) (process-mark proc)))) | |
73804d4b RS |
1124 | @end group |
1125 | @group | |
f9f59935 RS |
1126 | (save-excursion |
1127 | ;; @r{Insert the text, advancing the process marker.} | |
1128 | (goto-char (process-mark proc)) | |
1129 | (insert string) | |
1130 | (set-marker (process-mark proc) (point))) | |
1131 | (if moving (goto-char (process-mark proc)))))) | |
73804d4b RS |
1132 | @end group |
1133 | @end smallexample | |
1134 | ||
1135 | @noindent | |
f9f59935 RS |
1136 | The reason to use @code{with-current-buffer}, rather than using |
1137 | @code{save-excursion} to save and restore the current buffer, is so as | |
1138 | to preserve the change in point made by the second call to | |
1139 | @code{goto-char}. | |
73804d4b RS |
1140 | |
1141 | To make the filter force the process buffer to be visible whenever new | |
1142 | text arrives, insert the following line just before the | |
f9f59935 | 1143 | @code{with-current-buffer} construct: |
73804d4b RS |
1144 | |
1145 | @smallexample | |
1146 | (display-buffer (process-buffer proc)) | |
1147 | @end smallexample | |
1148 | ||
f9f59935 RS |
1149 | To force point to the end of the new output, no matter where it was |
1150 | previously, eliminate the variable @code{moving} and call | |
73804d4b RS |
1151 | @code{goto-char} unconditionally. |
1152 | ||
f9f59935 RS |
1153 | In earlier Emacs versions, every filter function that did regular |
1154 | expression searching or matching had to explicitly save and restore the | |
1155 | match data. Now Emacs does this automatically for filter functions; | |
1156 | they never need to do it explicitly. @xref{Match Data}. | |
73804d4b RS |
1157 | |
1158 | A filter function that writes the output into the buffer of the | |
bfe721d1 | 1159 | process should check whether the buffer is still alive. If it tries to |
f9f59935 RS |
1160 | insert into a dead buffer, it will get an error. The expression |
1161 | @code{(buffer-name (process-buffer @var{process}))} returns @code{nil} | |
1162 | if the buffer is dead. | |
73804d4b RS |
1163 | |
1164 | The output to the function may come in chunks of any size. A program | |
f9f59935 RS |
1165 | that produces the same output twice in a row may send it as one batch of |
1166 | 200 characters one time, and five batches of 40 characters the next. If | |
1167 | the filter looks for certain text strings in the subprocess output, make | |
1168 | sure to handle the case where one of these strings is split across two | |
1169 | or more batches of output. | |
73804d4b RS |
1170 | |
1171 | @defun set-process-filter process filter | |
1172 | This function gives @var{process} the filter function @var{filter}. If | |
1173 | @var{filter} is @code{nil}, it gives the process no filter. | |
1174 | @end defun | |
1175 | ||
1176 | @defun process-filter process | |
1177 | This function returns the filter function of @var{process}, or @code{nil} | |
1178 | if it has none. | |
1179 | @end defun | |
1180 | ||
1181 | Here is an example of use of a filter function: | |
1182 | ||
1183 | @smallexample | |
1184 | @group | |
1185 | (defun keep-output (process output) | |
1186 | (setq kept (cons output kept))) | |
1187 | @result{} keep-output | |
1188 | @end group | |
1189 | @group | |
1190 | (setq kept nil) | |
1191 | @result{} nil | |
1192 | @end group | |
1193 | @group | |
1194 | (set-process-filter (get-process "shell") 'keep-output) | |
1195 | @result{} keep-output | |
1196 | @end group | |
1197 | @group | |
1198 | (process-send-string "shell" "ls ~/other\n") | |
1199 | @result{} nil | |
1200 | kept | |
1201 | @result{} ("lewis@@slug[8] % " | |
1202 | @end group | |
1203 | @group | |
1204 | "FINAL-W87-SHORT.MSS backup.otl kolstad.mss~ | |
1205 | address.txt backup.psf kolstad.psf | |
1206 | backup.bib~ david.mss resume-Dec-86.mss~ | |
1207 | backup.err david.psf resume-Dec.psf | |
1208 | backup.mss dland syllabus.mss | |
1209 | " | |
1210 | "#backups.mss# backup.mss~ kolstad.mss | |
1211 | ") | |
1212 | @end group | |
1213 | @end smallexample | |
1214 | ||
1215 | @ignore @c The code in this example doesn't show the right way to do things. | |
1216 | Here is another, more realistic example, which demonstrates how to use | |
1217 | the process mark to do insertion in the same fashion as is done when | |
1218 | there is no filter function: | |
1219 | ||
1220 | @smallexample | |
1221 | @group | |
1222 | ;; @r{Insert input in the buffer specified by @code{my-shell-buffer}} | |
1223 | ;; @r{and make sure that buffer is shown in some window.} | |
1224 | (defun my-process-filter (proc str) | |
f9f59935 RS |
1225 | (let ((cur (selected-window)) |
1226 | (pop-up-windows t)) | |
1227 | (pop-to-buffer my-shell-buffer) | |
73804d4b RS |
1228 | @end group |
1229 | @group | |
f9f59935 RS |
1230 | (goto-char (point-max)) |
1231 | (insert str) | |
1232 | (set-marker (process-mark proc) (point-max)) | |
1233 | (select-window cur))) | |
73804d4b RS |
1234 | @end group |
1235 | @end smallexample | |
1236 | @end ignore | |
1237 | ||
582ef186 RS |
1238 | @node Decoding Output |
1239 | @subsection Decoding Process Output | |
1240 | ||
1241 | When Emacs writes process output directly into a multibyte buffer, | |
1242 | it decodes the output according to the process output coding system. | |
1243 | If the coding system is @code{raw-text} or @code{no-conversion}, Emacs | |
1244 | converts the unibyte output to multibyte using | |
fea5a6d5 | 1245 | @code{string-to-multibyte}, and inserts the resulting multibyte text. |
582ef186 RS |
1246 | |
1247 | You can use @code{set-process-coding-system} to specify which coding | |
1248 | system to use (@pxref{Process Information}). Otherwise, the coding | |
1249 | system comes from @code{coding-system-for-read}, if that is | |
1250 | non-@code{nil}; or else from the defaulting mechanism (@pxref{Default | |
1251 | Coding Systems}). | |
1252 | ||
1253 | @strong{Warning:} Coding systems such as @code{undecided} which | |
1254 | determine the coding system from the data do not work entirely | |
1255 | reliably with asynchronous subprocess output. This is because Emacs | |
1256 | has to process asynchronous subprocess output in batches, as it | |
1257 | arrives. Emacs must try to detect the proper coding system from one | |
1258 | batch at a time, and this does not always work. Therefore, if at all | |
1259 | possible, specify a coding system that determines both the character | |
1260 | code conversion and the end of line conversion---that is, one like | |
1261 | @code{latin-1-unix}, rather than @code{undecided} or @code{latin-1}. | |
1262 | ||
1263 | @cindex filter multibyte flag, of process | |
1264 | @cindex process filter multibyte flag | |
1265 | When Emacs calls a process filter function, it provides the process | |
1266 | output as a multibyte string or as a unibyte string according to the | |
1267 | process's filter multibyte flag. If the flag is non-@code{nil}, Emacs | |
1268 | decodes the output according to the process output coding system to | |
1269 | produce a multibyte string, and passes that to the process. If the | |
1270 | flag is @code{nil}, Emacs puts the output into a unibyte string, with | |
1271 | no decoding, and passes that. | |
1272 | ||
1273 | When you create a process, the filter multibyte flag takes its | |
1274 | initial value from @code{default-enable-multibyte-characters}. If you | |
1275 | want to change the flag later on, use | |
1276 | @code{set-process-filter-multibyte}. | |
1277 | ||
1278 | @defun set-process-filter-multibyte process multibyte | |
1279 | This function sets the filter multibyte flag of @var{process} | |
1280 | to @var{multibyte}. | |
1281 | @end defun | |
1282 | ||
1283 | @defun process-filter-multibyte-p process | |
1284 | This function returns the filter multibyte flag of @var{process}. | |
1285 | @end defun | |
1286 | ||
73804d4b RS |
1287 | @node Accepting Output |
1288 | @subsection Accepting Output from Processes | |
1289 | ||
1290 | Output from asynchronous subprocesses normally arrives only while | |
1291 | Emacs is waiting for some sort of external event, such as elapsed time | |
1292 | or terminal input. Occasionally it is useful in a Lisp program to | |
1293 | explicitly permit output to arrive at a specific point, or even to wait | |
1294 | until output arrives from a process. | |
1295 | ||
410bcc31 | 1296 | @defun accept-process-output &optional process seconds millisec just-this-one |
73804d4b RS |
1297 | This function allows Emacs to read pending output from processes. The |
1298 | output is inserted in the associated buffers or given to their filter | |
1299 | functions. If @var{process} is non-@code{nil} then this function does | |
1300 | not return until some output has been received from @var{process}. | |
1301 | ||
1302 | @c Emacs 19 feature | |
1303 | The arguments @var{seconds} and @var{millisec} let you specify timeout | |
1304 | periods. The former specifies a period measured in seconds and the | |
1305 | latter specifies one measured in milliseconds. The two time periods | |
1306 | thus specified are added together, and @code{accept-process-output} | |
1307 | returns after that much time whether or not there has been any | |
1308 | subprocess output. | |
1309 | ||
bfe721d1 KH |
1310 | The argument @var{seconds} need not be an integer. If it is a floating |
1311 | point number, this function waits for a fractional number of seconds. | |
1312 | Some systems support only a whole number of seconds; on these systems, | |
1911e6e5 | 1313 | @var{seconds} is rounded down. |
bfe721d1 | 1314 | |
73804d4b RS |
1315 | Not all operating systems support waiting periods other than multiples |
1316 | of a second; on those that do not, you get an error if you specify | |
1317 | nonzero @var{millisec}. | |
1318 | ||
bf247b6e | 1319 | @c Emacs 22.1 feature |
410bcc31 | 1320 | If @var{process} is a process, and the argument @var{just-this-one} is |
c1aa4864 | 1321 | non-@code{nil}, only output from that process is handled, suspending output |
410bcc31 KS |
1322 | from other processes until some output has been received from that |
1323 | process or the timeout expires. If @var{just-this-one} is an integer, | |
1324 | also inhibit running timers. This feature is generally not | |
1325 | recommended, but may be necessary for specific applications, such as | |
1326 | speech synthesis. | |
1327 | ||
73804d4b RS |
1328 | The function @code{accept-process-output} returns non-@code{nil} if it |
1329 | did get some output, or @code{nil} if the timeout expired before output | |
1330 | arrived. | |
1331 | @end defun | |
1332 | ||
1333 | @node Sentinels | |
1334 | @section Sentinels: Detecting Process Status Changes | |
1335 | @cindex process sentinel | |
1336 | @cindex sentinel | |
1337 | ||
1338 | A @dfn{process sentinel} is a function that is called whenever the | |
1339 | associated process changes status for any reason, including signals | |
1340 | (whether sent by Emacs or caused by the process's own actions) that | |
5517ea8a RS |
1341 | terminate, stop, or continue the process. The process sentinel is |
1342 | also called if the process exits. The sentinel receives two | |
1343 | arguments: the process for which the event occurred, and a string | |
1344 | describing the type of event. | |
73804d4b RS |
1345 | |
1346 | The string describing the event looks like one of the following: | |
1347 | ||
1348 | @itemize @bullet | |
177c0ea7 | 1349 | @item |
73804d4b RS |
1350 | @code{"finished\n"}. |
1351 | ||
1352 | @item | |
1353 | @code{"exited abnormally with code @var{exitcode}\n"}. | |
1354 | ||
1355 | @item | |
1356 | @code{"@var{name-of-signal}\n"}. | |
1357 | ||
1358 | @item | |
1359 | @code{"@var{name-of-signal} (core dumped)\n"}. | |
1360 | @end itemize | |
1361 | ||
5517ea8a RS |
1362 | A sentinel runs only while Emacs is waiting (e.g., for terminal |
1363 | input, or for time to elapse, or for process output). This avoids the | |
1364 | timing errors that could result from running them at random places in | |
1365 | the middle of other Lisp programs. A program can wait, so that | |
1366 | sentinels will run, by calling @code{sit-for} or @code{sleep-for} | |
78608595 | 1367 | (@pxref{Waiting}), or @code{accept-process-output} (@pxref{Accepting |
a9f0a989 | 1368 | Output}). Emacs also allows sentinels to run when the command loop is |
5517ea8a RS |
1369 | reading input. @code{delete-process} calls the sentinel when it |
1370 | terminates a running process. | |
1371 | ||
1372 | Emacs does not keep a queue of multiple reasons to call the sentinel | |
1373 | of one process; it records just the current status and the fact that | |
1374 | there has been a change. Therefore two changes in status, coming in | |
1375 | quick succession, can call the sentinel just once. However, process | |
1376 | termination will always run the sentinel exactly once. This is | |
1377 | because the process status can't change again after termination. | |
73804d4b | 1378 | |
75c0692f RS |
1379 | Emacs explicitly checks for output from the process before running |
1380 | the process sentinel. Once the sentinel runs due to process | |
1381 | termination, no further output can arrive from the process. | |
73804d4b RS |
1382 | |
1383 | A sentinel that writes the output into the buffer of the process | |
bfe721d1 | 1384 | should check whether the buffer is still alive. If it tries to insert |
73804d4b RS |
1385 | into a dead buffer, it will get an error. If the buffer is dead, |
1386 | @code{(buffer-name (process-buffer @var{process}))} returns @code{nil}. | |
1387 | ||
75c0692f RS |
1388 | Quitting is normally inhibited within a sentinel---otherwise, the |
1389 | effect of typing @kbd{C-g} at command level or to quit a user command | |
1390 | would be unpredictable. If you want to permit quitting inside a | |
1391 | sentinel, bind @code{inhibit-quit} to @code{nil}. In most cases, the | |
1392 | right way to do this is with the macro @code{with-local-quit}. | |
1393 | @xref{Quitting}. | |
1394 | ||
22697dac KH |
1395 | If an error happens during execution of a sentinel, it is caught |
1396 | automatically, so that it doesn't stop the execution of whatever | |
1397 | programs was running when the sentinel was started. However, if | |
1398 | @code{debug-on-error} is non-@code{nil}, the error-catching is turned | |
1399 | off. This makes it possible to use the Lisp debugger to debug the | |
1400 | sentinel. @xref{Debugger}. | |
1401 | ||
8a56d8ed RS |
1402 | While a sentinel is running, the process sentinel is temporarily |
1403 | set to @code{nil} so that the sentinel won't run recursively. | |
1404 | For this reason it is not possible for a sentinel to specify | |
1405 | a new sentinel. | |
1406 | ||
f9f59935 RS |
1407 | In earlier Emacs versions, every sentinel that did regular expression |
1408 | searching or matching had to explicitly save and restore the match data. | |
1409 | Now Emacs does this automatically for sentinels; they never need to do | |
1410 | it explicitly. @xref{Match Data}. | |
bfe721d1 | 1411 | |
73804d4b RS |
1412 | @defun set-process-sentinel process sentinel |
1413 | This function associates @var{sentinel} with @var{process}. If | |
1414 | @var{sentinel} is @code{nil}, then the process will have no sentinel. | |
1415 | The default behavior when there is no sentinel is to insert a message in | |
1416 | the process's buffer when the process status changes. | |
1417 | ||
5517ea8a RS |
1418 | Changes in process sentinel take effect immediately---if the sentinel |
1419 | is slated to be run but has not been called yet, and you specify a new | |
1420 | sentinel, the eventual call to the sentinel will use the new one. | |
1421 | ||
73804d4b RS |
1422 | @smallexample |
1423 | @group | |
1424 | (defun msg-me (process event) | |
1425 | (princ | |
1426 | (format "Process: %s had the event `%s'" process event))) | |
1427 | (set-process-sentinel (get-process "shell") 'msg-me) | |
1428 | @result{} msg-me | |
1429 | @end group | |
1430 | @group | |
1431 | (kill-process (get-process "shell")) | |
1432 | @print{} Process: #<process shell> had the event `killed' | |
1433 | @result{} #<process shell> | |
1434 | @end group | |
1435 | @end smallexample | |
1436 | @end defun | |
1437 | ||
1438 | @defun process-sentinel process | |
1439 | This function returns the sentinel of @var{process}, or @code{nil} if it | |
1440 | has none. | |
1441 | @end defun | |
1442 | ||
1443 | @defun waiting-for-user-input-p | |
1444 | While a sentinel or filter function is running, this function returns | |
1445 | non-@code{nil} if Emacs was waiting for keyboard input from the user at | |
1446 | the time the sentinel or filter function was called, @code{nil} if it | |
1447 | was not. | |
1448 | @end defun | |
1449 | ||
edc590bb | 1450 | @node Query Before Exit |
177c0ea7 | 1451 | @section Querying Before Exit |
edc590bb RS |
1452 | |
1453 | When Emacs exits, it terminates all its subprocesses by sending them | |
fea5a6d5 | 1454 | the @code{SIGHUP} signal. Because subprocesses may be doing |
edc590bb RS |
1455 | valuable work, Emacs normally asks the user to confirm that it is ok |
1456 | to terminate them. Each process has a query flag which, if | |
1457 | non-@code{nil}, says that Emacs should ask for confirmation before | |
1458 | exiting and thus killing that process. The default for the query flag | |
1459 | is @code{t}, meaning @emph{do} query. | |
1460 | ||
1461 | @tindex process-query-on-exit-flag | |
1462 | @defun process-query-on-exit-flag process | |
1463 | This returns the query flag of @var{process}. | |
1464 | @end defun | |
1465 | ||
1466 | @tindex set-process-query-on-exit-flag | |
1467 | @defun set-process-query-on-exit-flag process flag | |
1468 | This function sets the query flag of @var{process} to @var{flag}. It | |
1469 | returns @var{flag}. | |
1470 | ||
1471 | @smallexample | |
1472 | @group | |
1473 | ;; @r{Don't query about the shell process} | |
1474 | (set-process-query-on-exit-flag (get-process "shell") nil) | |
1475 | @result{} t | |
1476 | @end group | |
1477 | @end smallexample | |
1478 | @end defun | |
1479 | ||
1480 | @defun process-kill-without-query process &optional do-query | |
1481 | This function clears the query flag of @var{process}, so that | |
1482 | Emacs will not query the user on account of that process. | |
1483 | ||
1484 | Actually, the function does more than that: it returns the old value of | |
1485 | the process's query flag, and sets the query flag to @var{do-query}. | |
1486 | Please don't use this function to do those things any more---please | |
1487 | use the newer, cleaner functions @code{process-query-on-exit-flag} and | |
1488 | @code{set-process-query-on-exit-flag} in all but the simplest cases. | |
1489 | The only way you should use @code{process-kill-without-query} nowadays | |
1490 | is like this: | |
1491 | ||
1492 | @smallexample | |
1493 | @group | |
1494 | ;; @r{Don't query about the shell process} | |
1495 | (process-kill-without-query (get-process "shell")) | |
1496 | @end group | |
1497 | @end smallexample | |
1498 | @end defun | |
1499 | ||
73804d4b RS |
1500 | @node Transaction Queues |
1501 | @section Transaction Queues | |
1502 | @cindex transaction queue | |
1503 | ||
f9f59935 RS |
1504 | You can use a @dfn{transaction queue} to communicate with a subprocess |
1505 | using transactions. First use @code{tq-create} to create a transaction | |
1506 | queue communicating with a specified process. Then you can call | |
1507 | @code{tq-enqueue} to send a transaction. | |
73804d4b RS |
1508 | |
1509 | @defun tq-create process | |
1510 | This function creates and returns a transaction queue communicating with | |
1511 | @var{process}. The argument @var{process} should be a subprocess | |
1512 | capable of sending and receiving streams of bytes. It may be a child | |
78608595 | 1513 | process, or it may be a TCP connection to a server, possibly on another |
73804d4b RS |
1514 | machine. |
1515 | @end defun | |
1516 | ||
1517 | @defun tq-enqueue queue question regexp closure fn | |
1518 | This function sends a transaction to queue @var{queue}. Specifying the | |
1519 | queue has the effect of specifying the subprocess to talk to. | |
1520 | ||
78608595 | 1521 | The argument @var{question} is the outgoing message that starts the |
73804d4b RS |
1522 | transaction. The argument @var{fn} is the function to call when the |
1523 | corresponding answer comes back; it is called with two arguments: | |
1524 | @var{closure}, and the answer received. | |
1525 | ||
6f6fd5ef RS |
1526 | The argument @var{regexp} is a regular expression that should match |
1527 | text at the end of the entire answer, but nothing before; that's how | |
1528 | @code{tq-enqueue} determines where the answer ends. | |
73804d4b RS |
1529 | |
1530 | The return value of @code{tq-enqueue} itself is not meaningful. | |
1531 | @end defun | |
1532 | ||
1533 | @defun tq-close queue | |
1534 | Shut down transaction queue @var{queue}, waiting for all pending transactions | |
1535 | to complete, and then terminate the connection or child process. | |
1536 | @end defun | |
1537 | ||
1538 | Transaction queues are implemented by means of a filter function. | |
1539 | @xref{Filter Functions}. | |
1540 | ||
bfe721d1 KH |
1541 | @node Network |
1542 | @section Network Connections | |
1543 | @cindex network connection | |
73804d4b | 1544 | @cindex TCP |
0bbffed7 | 1545 | @cindex UDP |
73804d4b | 1546 | |
0bbffed7 KS |
1547 | Emacs Lisp programs can open stream (TCP) and datagram (UDP) network |
1548 | connections to other processes on the same machine or other machines. | |
1549 | A network connection is handled by Lisp much like a subprocess, and is | |
4bb24054 RS |
1550 | represented by a process object. However, the process you are |
1551 | communicating with is not a child of the Emacs process, so it has no | |
ad800164 | 1552 | process @acronym{ID}, and you can't kill it or send it signals. All you |
4bb24054 RS |
1553 | can do is send and receive data. @code{delete-process} closes the |
1554 | connection, but does not kill the program at the other end; that | |
1555 | program must decide what to do about closure of the connection. | |
1556 | ||
1557 | Lisp programs can listen for connections by creating network | |
1558 | servers. A network server is also represented by a kind of process | |
1559 | object, but unlike a network connection, the network server never | |
1560 | transfers data itself. When it receives a connection request, it | |
1561 | creates a new network connection to represent the connection just | |
1562 | made. (The network connection inherits certain information, including | |
1563 | the process plist, from the server.) The network server then goes | |
1564 | back to listening for more connection requests. | |
73804d4b | 1565 | |
78e54e2d KS |
1566 | Network connections and servers are created by calling |
1567 | @code{make-network-process} with an argument list consisting of | |
1568 | keyword/argument pairs, for example @code{:server t} to create a | |
1569 | server process, or @code{:type 'datagram} to create a datagram | |
30f4318d | 1570 | connection. @xref{Low-Level Network}, for details. You can also use |
3f7fab24 | 1571 | the @code{open-network-stream} function described below. |
78e54e2d | 1572 | |
73804d4b | 1573 | You can distinguish process objects representing network connections |
4bb24054 RS |
1574 | and servers from those representing subprocesses with the |
1575 | @code{process-status} function. The possible status values for | |
1576 | network connections are @code{open}, @code{closed}, @code{connect}, | |
1577 | and @code{failed}. For a network server, the status is always | |
1578 | @code{listen}. None of those values is possible for a real | |
1579 | subprocess. @xref{Process Information}. | |
1580 | ||
38e82e48 | 1581 | You can stop and resume operation of a network process by calling |
4bb24054 RS |
1582 | @code{stop-process} and @code{continue-process}. For a server |
1583 | process, being stopped means not accepting new connections. (Up to 5 | |
0bbffed7 KS |
1584 | connection requests will be queued for when you resume the server; you |
1585 | can increase this limit, unless it is imposed by the operating | |
c4a00aa2 | 1586 | system.) For a network stream connection, being stopped means not |
0bbffed7 | 1587 | processing input (any arriving input waits until you resume the |
312660e0 RS |
1588 | connection). For a datagram connection, some number of packets may be |
1589 | queued but input may be lost. You can use the function | |
1590 | @code{process-command} to determine whether a network connection or | |
1591 | server is stopped; a non-@code{nil} value means yes. | |
73804d4b RS |
1592 | |
1593 | @defun open-network-stream name buffer-or-name host service | |
4bb24054 RS |
1594 | This function opens a TCP connection, and returns a process object |
1595 | that represents the connection. | |
73804d4b RS |
1596 | |
1597 | The @var{name} argument specifies the name for the process object. It | |
1598 | is modified as necessary to make it unique. | |
1599 | ||
1600 | The @var{buffer-or-name} argument is the buffer to associate with the | |
1601 | connection. Output from the connection is inserted in the buffer, | |
1602 | unless you specify a filter function to handle the output. If | |
1603 | @var{buffer-or-name} is @code{nil}, it means that the connection is not | |
1604 | associated with any buffer. | |
1605 | ||
1606 | The arguments @var{host} and @var{service} specify where to connect to; | |
1607 | @var{host} is the host name (a string), and @var{service} is the name of | |
1608 | a defined network service (a string) or a port number (an integer). | |
1609 | @end defun | |
ab5796a9 | 1610 | |
4bb24054 RS |
1611 | @defun process-contact process &optional key |
1612 | This function returns information about how a network process was set | |
1613 | up. For a connection, when @var{key} is @code{nil}, it returns | |
1614 | @code{(@var{hostname} @var{service})} which specifies what you | |
1615 | connected to. | |
1616 | ||
1617 | If @var{key} is @code{t}, the value is the complete status information | |
1618 | for the connection or server; that is, the list of keywords and values | |
1619 | specified in @code{make-network-process}, except that some of the | |
1620 | values represent the current status instead of what you specified: | |
1621 | ||
1622 | @table @code | |
1623 | @item :buffer | |
1624 | The associated value is the process buffer. | |
1625 | @item :filter | |
1626 | The associated value is the process filter function. | |
1627 | @item :sentinel | |
0bbffed7 | 1628 | The associated value is the process sentinel function. |
4bb24054 RS |
1629 | @item :remote |
1630 | In a connection, this is the address in internal format of the remote peer. | |
1631 | @item :local | |
1632 | The local address, in internal format. | |
1633 | @item :service | |
1634 | In a server, if you specified @code{t} for @var{service}, | |
1635 | this value is the actual port number. | |
1636 | @end table | |
1637 | ||
1638 | @code{:local} and @code{:remote} are included even if they were not | |
1639 | specified explicitly in @code{make-network-process}. | |
1640 | ||
1641 | If @var{key} is a keyword, the function returns the value corresponding | |
1642 | to that keyword. | |
1643 | ||
1644 | For an ordinary child process, this function always returns @code{t}. | |
1645 | @end defun | |
1646 | ||
1647 | @node Network Servers | |
1648 | @section Network Servers | |
1649 | ||
1650 | You create a server by calling @code{make-network-process} with | |
1651 | @code{:server t}. The server will listen for connection requests from | |
1652 | clients. When it accepts a client connection request, that creates a | |
1653 | new network connection, itself a process object, with the following | |
1654 | parameters: | |
1655 | ||
1656 | @itemize @bullet | |
1657 | @item | |
1658 | The connection's process name is constructed by concatenating the | |
1659 | server process' @var{name} with a client identification string. The | |
1660 | client identification string for an IPv4 connection looks like | |
1661 | @samp{<@var{a}.@var{b}.@var{c}.@var{d}:@var{p}>}. Otherwise, it is a | |
0bbffed7 | 1662 | unique number in brackets, as in @samp{<@var{nnn}>}. The number |
4bb24054 RS |
1663 | is unique for each connection in the Emacs session. |
1664 | ||
1665 | @item | |
1666 | If the server's filter is non-@code{nil}, the connection process does | |
0bbffed7 | 1667 | not get a separate process buffer; otherwise, Emacs creates a new |
4bb24054 RS |
1668 | buffer for the purpose. The buffer name is the server's buffer name |
1669 | or process name, concatenated with the client identification string. | |
1670 | ||
1671 | The server's process buffer value is never used directly by Emacs, but | |
1672 | it is passed to the log function, which can log connections by | |
1673 | inserting text there. | |
1674 | ||
1675 | @item | |
1676 | The communication type and the process filter and sentinel are | |
1677 | inherited from those of the server. The server never directly | |
1678 | uses its filter and sentinel; their sole purpose is to initialize | |
1679 | connections made to the server. | |
1680 | ||
1681 | @item | |
1682 | The connection's process contact info is set according to the client's | |
1683 | addressing information (typically an IP address and a port number). | |
1684 | This information is associated with the @code{process-contact} | |
1685 | keywords @code{:host}, @code{:service}, @code{:remote}. | |
1686 | ||
1687 | @item | |
1688 | The connection's local address is set up according to the port | |
1689 | number used for the connection. | |
1690 | ||
1691 | @item | |
1692 | The client process' plist is initialized from the server's plist. | |
1693 | @end itemize | |
1694 | ||
4bb24054 | 1695 | @node Datagrams |
410bcc31 | 1696 | @section Datagrams |
4bb24054 RS |
1697 | @cindex datagrams |
1698 | ||
38e82e48 RS |
1699 | A datagram connection communicates with individual packets rather |
1700 | than streams of data. Each call to @code{process-send} sends one | |
1701 | datagram packet (@pxref{Input to Processes}), and each datagram | |
1702 | received results in one call to the filter function. | |
4bb24054 RS |
1703 | |
1704 | The datagram connection doesn't have to talk with the same remote | |
1705 | peer all the time. It has a @dfn{remote peer address} which specifies | |
1706 | where to send datagrams to. Each time an incoming datagram is passed | |
1707 | to the filter function, the peer address is set to the address that | |
1708 | datagram came from; that way, if the filter function sends a datagram, | |
1709 | it will go back to that place. You can specify the remote peer | |
1710 | address when you create the datagram connection using the | |
1711 | @code{:remote} keyword. You can change it later on by calling | |
1712 | @code{set-process-datagram-address}. | |
1713 | ||
1714 | @defun process-datagram-address process | |
1715 | If @var{process} is a datagram connection or server, this function | |
1716 | returns its remote peer address. | |
1717 | @end defun | |
1718 | ||
1719 | @defun set-process-datagram-address process address | |
1720 | If @var{process} is a datagram connection or server, this function | |
1721 | sets its remote peer address to @var{address}. | |
1722 | @end defun | |
1723 | ||
1724 | @node Low-Level Network | |
1725 | @section Low-Level Network Access | |
1726 | ||
088767cb RS |
1727 | You can also create network connections by operating at a lower |
1728 | level that that of @code{open-network-stream}, using | |
1729 | @code{make-network-process}. | |
1730 | ||
1731 | @menu | |
1732 | * Make Network:: Using @code{make-network-process}. | |
1733 | * Network Options:: Further control over network connections. | |
1734 | * Network Feature Testing:: Determining which network features work on | |
1735 | the machine you are using. | |
1736 | @end menu | |
1737 | ||
1738 | @node Make Network | |
1739 | @subsection @code{make-network-process} | |
1740 | ||
4bb24054 RS |
1741 | The basic function for creating network connections and network |
1742 | servers is @code{make-network-process}. It can do either of those | |
1743 | jobs, depending on the arguments you give it. | |
1744 | ||
1745 | @defun make-network-process &rest args | |
1746 | This function creates a network connection or server and returns the | |
1747 | process object that represents it. The arguments @var{args} are a | |
1748 | list of keyword/argument pairs. Omitting a keyword is always | |
1749 | equivalent to specifying it with value @code{nil}, except for | |
0bbffed7 KS |
1750 | @code{:coding}, @code{:filter-multibyte}, and @code{:reuseaddr}. Here |
1751 | are the meaningful keywords: | |
4bb24054 RS |
1752 | |
1753 | @table @asis | |
138ed6bc | 1754 | @item :name @var{name} |
4bb24054 RS |
1755 | Use the string @var{name} as the process name. It is modified if |
1756 | necessary to make it unique. | |
1757 | ||
1758 | @item :type @var{type} | |
1759 | Specify the communication type. A value of @code{nil} specifies a | |
1760 | stream connection (the default); @code{datagram} specifies a datagram | |
1761 | connection. Both connections and servers can be of either type. | |
1762 | ||
1763 | @item :server @var{server-flag} | |
1764 | If @var{server-flag} is non-@code{nil}, create a server. Otherwise, | |
0bbffed7 KS |
1765 | create a connection. For a stream type server, @var{server-flag} may |
1766 | be an integer which then specifies the length of the queue of pending | |
1767 | connections to the server. The default queue length is 5. | |
4bb24054 RS |
1768 | |
1769 | @item :host @var{host} | |
1770 | Specify the host to connect to. @var{host} should be a host name or | |
1771 | internet address, as a string, or the symbol @code{local} to specify | |
1772 | the local host. If you specify @var{host} for a server, it must | |
1773 | specify a valid address for the local host, and only clients | |
1774 | connecting to that address will be accepted. | |
1775 | ||
1776 | @item :service @var{service} | |
1777 | @var{service} specifies a port number to connect to, or, for a server, | |
1778 | the port number to listen on. It should be a service name that | |
1779 | translates to a port number, or an integer specifying the port number | |
1780 | directly. For a server, it can also be @code{t}, which means to let | |
1781 | the system select an unused port number. | |
1782 | ||
1783 | @item :family @var{family} | |
1784 | @var{family} specifies the address (and protocol) family for | |
d9043ddf RS |
1785 | communication. @code{nil} means determine the proper address family |
1786 | automatically for the given @var{host} and @var{service}. | |
1787 | @code{local} specifies a Unix socket, in which case @var{host} is | |
1788 | ignored. @code{ipv4} and @code{ipv6} specify to use IPv4 and IPv6 | |
1789 | respectively. | |
4bb24054 RS |
1790 | |
1791 | @item :local @var{local-address} | |
1792 | For a server process, @var{local-address} is the address to listen on. | |
1793 | It overrides @var{family}, @var{host} and @var{service}, and you | |
1794 | may as well not specify them. | |
1795 | ||
1796 | @item :remote @var{remote-address} | |
1797 | For a connection, @var{remote-address} is the address to connect to. | |
1798 | It overrides @var{family}, @var{host} and @var{service}, and you | |
1799 | may as well not specify them. | |
1800 | ||
1801 | For a datagram server, @var{remote-address} specifies the initial | |
1802 | setting of the remote datagram address. | |
1803 | ||
1804 | The format of @var{local-address} or @var{remote-address} depends on | |
1805 | the address family: | |
1806 | ||
1807 | @itemize - | |
1808 | @item | |
b944a155 KS |
1809 | An IPv4 address is represented as a five-element vector of four 8-bit |
1810 | integers and one 16-bit integer | |
1811 | @code{[@var{a} @var{b} @var{c} @var{d} @var{p}]} corresponding to | |
1812 | numeric IPv4 address @var{a}.@var{b}.@var{c}.@var{d} and port number | |
1813 | @var{p}. | |
1814 | ||
1815 | @item | |
1816 | An IPv6 address is represented as a nine-element vector of 16-bit | |
1817 | integers @code{[@var{a} @var{b} @var{c} @var{d} @var{e} @var{f} | |
1818 | @var{g} @var{h} @var{p}]} corresponding to numeric IPv6 address | |
1819 | @var{a}:@var{b}:@var{c}:@var{d}:@var{e}:@var{f}:@var{g}:@var{h} and | |
1820 | port number @var{p}. | |
4bb24054 RS |
1821 | |
1822 | @item | |
1823 | A local address is represented as a string which specifies the address | |
1824 | in the local address space. | |
1825 | ||
1826 | @item | |
1827 | An ``unsupported family'' address is represented by a cons | |
1828 | @code{(@var{f} . @var{av})}, where @var{f} is the family number and | |
38e82e48 RS |
1829 | @var{av} is a vector specifying the socket address using one element |
1830 | per address data byte. Do not rely on this format in portable code, | |
1831 | as it may depend on implementation defined constants, data sizes, and | |
1832 | data structure alignment. | |
4bb24054 RS |
1833 | @end itemize |
1834 | ||
1835 | @item :nowait @var{bool} | |
1836 | If @var{bool} is non-@code{nil} for a stream connection, return | |
1837 | without waiting for the connection to complete. When the connection | |
1838 | succeeds or fails, Emacs will call the sentinel function, with a | |
1839 | second argument matching @code{"open"} (if successful) or | |
1840 | @code{"failed"}. The default is to block, so that | |
1841 | @code{make-network-process} does not return until the connection | |
1842 | has succeeded or failed. | |
1843 | ||
1844 | @item :stop @var{stopped} | |
1845 | Start the network connection or server in the `stopped' state if | |
1846 | @var{stopped} is non-@code{nil}. | |
1847 | ||
1848 | @item :buffer @var{buffer} | |
1849 | Use @var{buffer} as the process buffer. | |
1850 | ||
1851 | @item :coding @var{coding} | |
1852 | Use @var{coding} as the coding system for this process. To specify | |
1853 | different coding systems for decoding data from the connection and for | |
1854 | encoding data sent to it, specify @code{(@var{decoding} . | |
1855 | @var{encoding})} for @var{coding}. | |
1856 | ||
1857 | If you don't specify this keyword at all, the default | |
0bbffed7 | 1858 | is to determine the coding systems from the data. |
4bb24054 RS |
1859 | |
1860 | @item :noquery @var{query-flag} | |
3f7fab24 LT |
1861 | Initialize the process query flag to @var{query-flag}. |
1862 | @xref{Query Before Exit}. | |
4bb24054 RS |
1863 | |
1864 | @item :filter @var{filter} | |
1865 | Initialize the process filter to @var{filter}. | |
1866 | ||
1867 | @item :filter-multibyte @var{bool} | |
1868 | If @var{bool} is non-@code{nil}, strings given to the process filter | |
1869 | are multibyte, otherwise they are unibyte. If you don't specify this | |
1870 | keyword at all, the default is that the strings are multibyte if | |
1871 | @code{default-enable-multibyte-characters} is non-@code{nil}. | |
1872 | ||
1873 | @item :sentinel @var{sentinel} | |
1874 | Initialize the process sentinel to @var{sentinel}. | |
1875 | ||
1876 | @item :log @var{log} | |
1877 | Initialize the log function of a server process to @var{log}. The log | |
1878 | function is called each time the server accepts a network connection | |
1879 | from a client. The arguments passed to the log function are | |
1880 | @var{server}, @var{connection}, and @var{message}, where @var{server} | |
1881 | is the server process, @var{connection} is the new process for the | |
1882 | connection, and @var{message} is a string describing what has | |
1883 | happened. | |
1884 | ||
1885 | @item :plist @var{plist} | |
1886 | Initialize the process plist to @var{plist}. | |
1887 | @end table | |
1888 | ||
088767cb RS |
1889 | The original argument list, modified with the actual connection |
1890 | information, is available via the @code{process-contact} function. | |
1891 | @end defun | |
1892 | ||
1893 | @node Network Options | |
1894 | @subsection Network Options | |
0bbffed7 | 1895 | |
088767cb RS |
1896 | The following network options can be specified when you create a |
1897 | network process. Except for @code{:reuseaddr}, you can also set or | |
1898 | modify these options later, using @code{set-network-process-option}. | |
1899 | ||
1900 | For a server process, the options specified with | |
0bbffed7 KS |
1901 | @code{make-network-process} are not inherited by the client |
1902 | connections, so you will need to set the necessary options for each | |
088767cb | 1903 | child connection as it is created. |
0bbffed7 | 1904 | |
41beda59 | 1905 | @table @asis |
0bbffed7 KS |
1906 | @item :bindtodevice @var{device-name} |
1907 | If @var{device-name} is a non-empty string identifying a network | |
1908 | interface name (see @code{network-interface-list}), only handle | |
00991494 JH |
1909 | packets received on that interface. If @var{device-name} is @code{nil} |
1910 | (the default), handle packets received on any interface. | |
0bbffed7 KS |
1911 | |
1912 | Using this option may require special privileges on some systems. | |
1913 | ||
1914 | @item :broadcast @var{broadcast-flag} | |
1915 | If @var{broadcast-flag} is non-@code{nil} for a datagram process, the | |
1916 | process will receive datagram packet sent to a broadcast address, and | |
1917 | be able to send packets to a broadcast address. Ignored for a stream | |
1918 | connection. | |
1919 | ||
1920 | @item :dontroute @var{dontroute-flag} | |
1921 | If @var{dontroute-flag} is non-@code{nil}, the process can only send | |
1922 | to hosts on the same network as the local host. | |
1923 | ||
1924 | @item :keepalive @var{keepalive-flag} | |
1925 | If @var{keepalive-flag} is non-@code{nil} for a stream connection, | |
491cd154 | 1926 | enable exchange of low-level keep-alive messages. |
0bbffed7 KS |
1927 | |
1928 | @item :linger @var{linger-arg} | |
1929 | If @var{linger-arg} is non-@code{nil}, wait for successful | |
1930 | transmission of all queued packets on the connection before it is | |
1931 | deleted (see @code{delete-process}). If @var{linger-arg} is an | |
1932 | integer, it specifies the maximum time in seconds to wait for queued | |
1933 | packets to be sent before closing the connection. Default is | |
1934 | @code{nil} which means to discard unsent queued packets when the | |
1935 | process is deleted. | |
1936 | ||
1937 | @item :oobinline @var{oobinline-flag} | |
1938 | If @var{oobinline-flag} is non-@code{nil} for a stream connection, | |
1939 | receive out-of-band data in the normal data stream. Otherwise, ignore | |
1940 | out-of-band data. | |
1941 | ||
1942 | @item :priority @var{priority} | |
1943 | Set the priority for packets sent on this connection to the integer | |
1944 | @var{priority}. The interpretation of this number is protocol | |
1945 | specific, such as setting the TOS (type of service) field on IP | |
1946 | packets sent on this connection. It may also have system dependent | |
1947 | effects, such as selecting a specific output queue on the network | |
1948 | interface. | |
1949 | ||
1950 | @item :reuseaddr @var{reuseaddr-flag} | |
1951 | If @var{reuseaddr-flag} is non-@code{nil} (the default) for a stream | |
1952 | server process, allow this server to reuse a specific port number (see | |
1953 | @code{:service}) unless another process on this host is already | |
1954 | listening on that port. If @var{reuseaddr-flag} is @code{nil}, there | |
1955 | may be a period of time after the last use of that port (by any | |
1956 | process on the host), where it is not possible to make a new server on | |
1957 | that port. | |
0bbffed7 KS |
1958 | @end table |
1959 | ||
0bbffed7 KS |
1960 | @defun set-network-process-option process option value |
1961 | This function sets or modifies a network option for network process | |
1962 | @var{process}. See @code{make-network-process} for details of options | |
1963 | @var{option} and their corresponding values @var{value}. | |
1964 | ||
1965 | The current setting of an option is available via the | |
f3544d11 | 1966 | @code{process-contact} function. |
0bbffed7 KS |
1967 | @end defun |
1968 | ||
088767cb RS |
1969 | @node Network Feature Testing |
1970 | @subsection Testing Availability of Network Features | |
4bb24054 RS |
1971 | |
1972 | To test for the availability of a given network feature, use | |
1973 | @code{featurep} like this: | |
1974 | ||
1975 | @example | |
1976 | (featurep 'make-network-process '(@var{keyword} @var{value})) | |
410bcc31 | 1977 | @end example |
4bb24054 RS |
1978 | |
1979 | @noindent | |
0bbffed7 KS |
1980 | The result of the first form is @code{t} if it works to specify |
1981 | @var{keyword} with value @var{value} in @code{make-network-process}. | |
1982 | The result of the second form is @code{t} if @var{keyword} is | |
1983 | supported by @code{make-network-process}. Here are some of the | |
1984 | @var{keyword}---@var{value} pairs you can test in | |
1985 | this way. | |
4bb24054 RS |
1986 | |
1987 | @table @code | |
1988 | @item (:nowait t) | |
1989 | Non-@code{nil} if non-blocking connect is supported. | |
1990 | @item (:type datagram) | |
1991 | Non-@code{nil} if datagrams are supported. | |
1992 | @item (:family local) | |
1993 | Non-@code{nil} if local (aka ``UNIX domain'') sockets are supported. | |
b944a155 KS |
1994 | @item (:family ipv6) |
1995 | Non-@code{nil} if IPv6 is supported. | |
4bb24054 RS |
1996 | @item (:service t) |
1997 | Non-@code{nil} if the system can select the port for a server. | |
0bbffed7 KS |
1998 | @end table |
1999 | ||
2000 | To test for the availability of a given network option, use | |
2001 | @code{featurep} like this: | |
2002 | ||
2003 | @example | |
2004 | (featurep 'make-network-process '@var{keyword}) | |
410bcc31 | 2005 | @end example |
0bbffed7 | 2006 | |
088767cb RS |
2007 | @noindent |
2008 | Here are some of the options you can test in this way. | |
0bbffed7 KS |
2009 | |
2010 | @table @code | |
2011 | @item :bindtodevice | |
2012 | @itemx :broadcast | |
2013 | @itemx :dontroute | |
2014 | @itemx :keepalive | |
2015 | @itemx :linger | |
2016 | @itemx :oobinline | |
2017 | @itemx :priority | |
2018 | @itemx :reuseaddr | |
2019 | That particular network option is supported by | |
2020 | @code{make-network-process} and @code{set-network-process-option}. | |
4bb24054 RS |
2021 | @end table |
2022 | ||
088767cb RS |
2023 | @node Misc Network |
2024 | @section Misc Network Facilities | |
2025 | ||
2026 | These additional functions are useful for creating and operating | |
2027 | on network connections. | |
2028 | ||
2029 | @defun network-interface-list | |
2030 | This function returns a list describing the network interfaces | |
2031 | of the machine you are using. The value is an alist whose | |
2032 | elements have the form @code{(@var{name} . @var{address})}. | |
2033 | @var{address} has the same form as the @var{local-address} | |
2034 | and @var{remote-address} arguments to @code{make-network-process}. | |
2035 | @end defun | |
2036 | ||
2037 | @defun network-interface-info ifname | |
2038 | This function returns information about the network interface named | |
2039 | @var{ifname}. The value is a list of the form | |
2040 | @code{(@var{addr} @var{bcast} @var{netmask} @var{hwaddr} @var{flags})}. | |
2041 | ||
2042 | @table @var | |
2043 | @item addr | |
2044 | The internet protocol address. | |
2045 | @item bcast | |
2046 | The broadcast address. | |
2047 | @item netmask | |
2048 | The network mask. | |
2049 | @item hwaddr | |
2050 | The layer 2 address (Ethernet MAC address, for instance). | |
2051 | @item flags | |
2052 | The current flags of the interface. | |
2053 | @end table | |
2054 | @end defun | |
2055 | ||
2056 | @defun format-network-address address &optional omit-port | |
2057 | This function converts the Lisp representation of a network address to | |
b944a155 | 2058 | a string. |
d9043ddf RS |
2059 | |
2060 | A five-element vector @code{[@var{a} @var{b} @var{c} @var{d} @var{p}]} | |
2061 | represents an IPv4 address @var{a}.@var{b}.@var{c}.@var{d} and port | |
2062 | number @var{p}. @code{format-network-address} converts that to the | |
2063 | string @code{"@var{a}.@var{b}.@var{c}.@var{d}:@var{p}"}. | |
2064 | ||
2065 | A nine-element vector @code{[@var{a} @var{b} @var{c} @var{d} @var{e} | |
b944a155 KS |
2066 | @var{f} @var{g} @var{h} @var{p}]} represents an IPv6 address and port |
2067 | number. @code{format-network-address} converts that to the string | |
2068 | @code{"[@var{a}:@var{b}:@var{c}:@var{d}:@var{e}:@var{f}:@var{g}:@var{h}]:@var{p}"}. | |
088767cb | 2069 | |
d9043ddf RS |
2070 | If the vector does not include the port number, @var{p}, or if |
2071 | @var{omit-port} is non-@code{nil}, the result does not include the | |
2072 | @code{:@var{p}} suffix. | |
088767cb RS |
2073 | @end defun |
2074 | ||
377ddd88 RS |
2075 | @node Byte Packing |
2076 | @section Packing and Unpacking Byte Arrays | |
2077 | ||
2078 | This section describes how to pack and unpack arrays of bytes, | |
926c4c9b LT |
2079 | usually for binary network protocols. These functions convert byte arrays |
2080 | to alists, and vice versa. The byte array can be represented as a | |
377ddd88 RS |
2081 | unibyte string or as a vector of integers, while the alist associates |
2082 | symbols either with fixed-size objects or with recursive sub-alists. | |
2083 | ||
2084 | @cindex serializing | |
2085 | @cindex deserializing | |
2086 | @cindex packing | |
2087 | @cindex unpacking | |
2088 | Conversion from byte arrays to nested alists is also known as | |
2089 | @dfn{deserializing} or @dfn{unpacking}, while going in the opposite | |
2090 | direction is also known as @dfn{serializing} or @dfn{packing}. | |
2091 | ||
2092 | @menu | |
2093 | * Bindat Spec:: Describing data layout. | |
2094 | * Bindat Functions:: Doing the unpacking and packing. | |
2095 | * Bindat Examples:: Samples of what bindat.el can do for you! | |
2096 | @end menu | |
2097 | ||
2098 | @node Bindat Spec | |
2099 | @subsection Describing Data Layout | |
2100 | ||
2101 | To control unpacking and packing, you write a @dfn{data layout | |
2102 | specification}, a special nested list describing named and typed | |
b9646a71 | 2103 | @dfn{fields}. This specification controls length of each field to be |
377ddd88 RS |
2104 | processed, and how to pack or unpack it. |
2105 | ||
2106 | @cindex endianness | |
2107 | @cindex big endian | |
2108 | @cindex little endian | |
2109 | @cindex network byte ordering | |
2110 | A field's @dfn{type} describes the size (in bytes) of the object | |
2111 | that the field represents and, in the case of multibyte fields, how | |
3f7fab24 | 2112 | the bytes are ordered within the field. The two possible orderings |
377ddd88 RS |
2113 | are ``big endian'' (also known as ``network byte ordering'') and |
2114 | ``little endian''. For instance, the number @code{#x23cd} (decimal | |
2115 | 9165) in big endian would be the two bytes @code{#x23} @code{#xcd}; | |
2116 | and in little endian, @code{#xcd} @code{#x23}. Here are the possible | |
2117 | type values: | |
2118 | ||
2119 | @table @code | |
2120 | @item u8 | |
2121 | @itemx byte | |
2122 | Unsigned byte, with length 1. | |
2123 | ||
2124 | @item u16 | |
2125 | @itemx word | |
2126 | @itemx short | |
2127 | Unsigned integer in network byte order, with length 2. | |
2128 | ||
2129 | @item u24 | |
2130 | Unsigned integer in network byte order, with length 3. | |
2131 | ||
2132 | @item u32 | |
2133 | @itemx dword | |
2134 | @itemx long | |
2135 | Unsigned integer in network byte order, with length 4. | |
2136 | Note: These values may be limited by Emacs' integer implementation limits. | |
2137 | ||
2138 | @item u16r | |
2139 | @itemx u24r | |
2140 | @itemx u32r | |
2141 | Unsigned integer in little endian order, with length 2, 3 and 4, respectively. | |
2142 | ||
2143 | @item str @var{len} | |
2144 | String of length @var{len}. | |
2145 | ||
2146 | @item strz @var{len} | |
2147 | Zero-terminated string of length @var{len}. | |
2148 | ||
2149 | @item vec @var{len} | |
2150 | Vector of @var{len} bytes. | |
2151 | ||
2152 | @item ip | |
2153 | Four-byte vector representing an Internet address. For example: | |
2154 | @code{[127 0 0 1]} for localhost. | |
2155 | ||
2156 | @item bits @var{len} | |
2157 | List of set bits in @var{len} bytes. The bytes are taken in big | |
2158 | endian order and the bits are numbered starting with @code{8 * | |
3f7fab24 | 2159 | @var{len} @minus{} 1} and ending with zero. For example: @code{bits |
377ddd88 RS |
2160 | 2} unpacks @code{#x28} @code{#x1c} to @code{(2 3 4 11 13)} and |
2161 | @code{#x1c} @code{#x28} to @code{(3 5 10 11 12)}. | |
2162 | ||
2163 | @item (eval @var{form}) | |
2164 | @var{form} is a Lisp expression evaluated at the moment the field is | |
2165 | unpacked or packed. The result of the evaluation should be one of the | |
2166 | above-listed type specifications. | |
2167 | @end table | |
2168 | ||
2169 | A field specification generally has the form @code{([@var{name}] | |
2170 | @var{handler})}. The square braces indicate that @var{name} is | |
2171 | optional. (Don't use names that are symbols meaningful as type | |
2172 | specifications (above) or handler specifications (below), since that | |
2173 | would be ambiguous.) @var{name} can be a symbol or the expression | |
2174 | @code{(eval @var{form})}, in which case @var{form} should evaluate to | |
2175 | a symbol. | |
2176 | ||
2177 | @var{handler} describes how to unpack or pack the field and can be one | |
2178 | of the following: | |
2179 | ||
2180 | @table @code | |
2181 | @item @var{type} | |
2182 | Unpack/pack this field according to the type specification @var{type}. | |
2183 | ||
2184 | @item eval @var{form} | |
2185 | Evaluate @var{form}, a Lisp expression, for side-effect only. If the | |
2186 | field name is specified, the value is bound to that field name. | |
2187 | @var{form} can access and update these dynamically bound variables: | |
2188 | ||
2189 | @table @code | |
2190 | @item raw-data | |
2191 | The data as a byte array. | |
2192 | ||
2193 | @item pos | |
2194 | Current position of the unpacking or packing operation. | |
2195 | ||
2196 | @item struct | |
2197 | Alist. | |
2198 | ||
2199 | @item last | |
2200 | Value of the last field processed. | |
2201 | @end table | |
2202 | ||
2203 | @item fill @var{len} | |
2204 | Skip @var{len} bytes. In packing, this leaves them unchanged, | |
2205 | which normally means they remain zero. In unpacking, this means | |
2206 | they are ignored. | |
2207 | ||
2208 | @item align @var{len} | |
2209 | Skip to the next multiple of @var{len} bytes. | |
2210 | ||
2211 | @item struct @var{spec-name} | |
3f7fab24 | 2212 | Process @var{spec-name} as a sub-specification. This describes a |
377ddd88 RS |
2213 | structure nested within another structure. |
2214 | ||
2215 | @item union @var{form} (@var{tag} @var{spec})@dots{} | |
2216 | @c ??? I don't see how one would actually use this. | |
2217 | @c ??? what kind of expression would be useful for @var{form}? | |
2218 | Evaluate @var{form}, a Lisp expression, find the first @var{tag} | |
2219 | that matches it, and process its associated data layout specification | |
2220 | @var{spec}. Matching can occur in one of three ways: | |
2221 | ||
2222 | @itemize | |
2223 | @item | |
2224 | If a @var{tag} has the form @code{(eval @var{expr})}, evaluate | |
2225 | @var{expr} with the variable @code{tag} dynamically bound to the value | |
2226 | of @var{form}. A non-@code{nil} result indicates a match. | |
2227 | ||
2228 | @item | |
2229 | @var{tag} matches if it is @code{equal} to the value of @var{form}. | |
2230 | ||
2231 | @item | |
2232 | @var{tag} matches unconditionally if it is @code{t}. | |
2233 | @end itemize | |
2234 | ||
2235 | @item repeat @var{count} @var{field-spec}@dots{} | |
2236 | @var{count} may be an integer, or a list of one element naming a | |
2237 | previous field. For correct operation, each @var{field-spec} must | |
2238 | include a name. | |
2239 | @c ??? What does it MEAN? | |
2240 | @end table | |
2241 | ||
2242 | @node Bindat Functions | |
2243 | @subsection Functions to Unpack and Pack Bytes | |
2244 | ||
2245 | In the following documentation, @var{spec} refers to a data layout | |
2246 | specification, @code{raw-data} to a byte array, and @var{struct} to an | |
2247 | alist representing unpacked field data. | |
2248 | ||
2249 | @defun bindat-unpack spec raw-data &optional pos | |
2250 | This function unpacks data from the byte array @code{raw-data} | |
2251 | according to @var{spec}. Normally this starts unpacking at the | |
2252 | beginning of the byte array, but if @var{pos} is non-@code{nil}, it | |
2253 | specifies a zero-based starting position to use instead. | |
2254 | ||
2255 | The value is an alist or nested alist in which each element describes | |
2256 | one unpacked field. | |
2257 | @end defun | |
2258 | ||
2259 | @defun bindat-get-field struct &rest name | |
2260 | This function selects a field's data from the nested alist | |
2261 | @var{struct}. Usually @var{struct} was returned by | |
2262 | @code{bindat-unpack}. If @var{name} corresponds to just one argument, | |
2263 | that means to extract a top-level field value. Multiple @var{name} | |
2264 | arguments specify repeated lookup of sub-structures. An integer name | |
2265 | acts as an array index. | |
2266 | ||
2267 | For example, if @var{name} is @code{(a b 2 c)}, that means to find | |
cbce0752 | 2268 | field @code{c} in the third element of subfield @code{b} of field |
377ddd88 RS |
2269 | @code{a}. (This corresponds to @code{struct.a.b[2].c} in C.) |
2270 | @end defun | |
2271 | ||
2272 | @defun bindat-length spec struct | |
2273 | @c ??? I don't understand this at all -- rms | |
2274 | This function returns the length in bytes of @var{struct}, according | |
2275 | to @var{spec}. | |
2276 | @end defun | |
2277 | ||
2278 | @defun bindat-pack spec struct &optional raw-data pos | |
2279 | This function returns a byte array packed according to @var{spec} from | |
2280 | the data in the alist @var{struct}. Normally it creates and fills a | |
2281 | new byte array starting at the beginning. However, if @var{raw-data} | |
3f7fab24 | 2282 | is non-@code{nil}, it specifies a pre-allocated string or vector to |
377ddd88 RS |
2283 | pack into. If @var{pos} is non-@code{nil}, it specifies the starting |
2284 | offset for packing into @code{raw-data}. | |
2285 | ||
3f7fab24 | 2286 | @c ??? Isn't this a bug? Shouldn't it always be unibyte? |
377ddd88 RS |
2287 | Note: The result is a multibyte string; use @code{string-make-unibyte} |
2288 | on it to make it unibyte if necessary. | |
2289 | @end defun | |
2290 | ||
2291 | @defun bindat-ip-to-string ip | |
2292 | Convert the Internet address vector @var{ip} to a string in the usual | |
2293 | dotted notation. | |
2294 | ||
2295 | @example | |
2296 | (bindat-ip-to-string [127 0 0 1]) | |
2297 | @result{} "127.0.0.1" | |
2298 | @end example | |
2299 | @end defun | |
2300 | ||
2301 | @node Bindat Examples | |
2302 | @subsection Examples of Byte Unpacking and Packing | |
2303 | ||
2304 | Here is a complete example of byte unpacking and packing: | |
2305 | ||
be87af26 | 2306 | @lisp |
377ddd88 RS |
2307 | (defvar fcookie-index-spec |
2308 | '((:version u32) | |
2309 | (:count u32) | |
2310 | (:longest u32) | |
2311 | (:shortest u32) | |
2312 | (:flags u32) | |
2313 | (:delim u8) | |
2314 | (:ignored fill 3) | |
2315 | (:offset repeat (:count) | |
2316 | (:foo u32))) | |
2317 | "Description of a fortune cookie index file's contents.") | |
2318 | ||
2319 | (defun fcookie (cookies &optional index) | |
2320 | "Display a random fortune cookie from file COOKIES. | |
2321 | Optional second arg INDEX specifies the associated index | |
2322 | filename, which is by default constructed by appending | |
2323 | \".dat\" to COOKIES. Display cookie text in possibly | |
2324 | new buffer \"*Fortune Cookie: BASENAME*\" where BASENAME | |
2325 | is COOKIES without the directory part." | |
2326 | (interactive "fCookies file: ") | |
2327 | (let* ((info (with-temp-buffer | |
2328 | (insert-file-contents-literally | |
2329 | (or index (concat cookies ".dat"))) | |
2330 | (bindat-unpack fcookie-index-spec | |
2331 | (buffer-string)))) | |
2332 | (sel (random (bindat-get-field info :count))) | |
2333 | (beg (cdar (bindat-get-field info :offset sel))) | |
342fd6cd RS |
2334 | (end (or (cdar (bindat-get-field info |
2335 | :offset (1+ sel))) | |
377ddd88 | 2336 | (nth 7 (file-attributes cookies))))) |
342fd6cd RS |
2337 | (switch-to-buffer |
2338 | (get-buffer-create | |
2339 | (format "*Fortune Cookie: %s*" | |
2340 | (file-name-nondirectory cookies)))) | |
377ddd88 | 2341 | (erase-buffer) |
342fd6cd RS |
2342 | (insert-file-contents-literally |
2343 | cookies nil beg (- end 3)))) | |
377ddd88 RS |
2344 | |
2345 | (defun fcookie-create-index (cookies &optional index delim) | |
2346 | "Scan file COOKIES, and write out its index file. | |
2347 | Optional second arg INDEX specifies the index filename, | |
2348 | which is by default constructed by appending \".dat\" to | |
2349 | COOKIES. Optional third arg DELIM specifies the unibyte | |
2350 | character which, when found on a line of its own in | |
2351 | COOKIES, indicates the border between entries." | |
2352 | (interactive "fCookies file: ") | |
2353 | (setq delim (or delim ?%)) | |
2354 | (let ((delim-line (format "\n%c\n" delim)) | |
2355 | (count 0) | |
2356 | (max 0) | |
2357 | min p q len offsets) | |
2358 | (unless (= 3 (string-bytes delim-line)) | |
2359 | (error "Delimiter cannot be represented in one byte")) | |
2360 | (with-temp-buffer | |
2361 | (insert-file-contents-literally cookies) | |
2362 | (while (and (setq p (point)) | |
2363 | (search-forward delim-line (point-max) t) | |
2364 | (setq len (- (point) 3 p))) | |
2365 | (setq count (1+ count) | |
2366 | max (max max len) | |
2367 | min (min (or min max) len) | |
2368 | offsets (cons (1- p) offsets)))) | |
2369 | (with-temp-buffer | |
2370 | (set-buffer-multibyte nil) | |
342fd6cd RS |
2371 | (insert |
2372 | (string-make-unibyte | |
2373 | (bindat-pack | |
2374 | fcookie-index-spec | |
2375 | `((:version . 2) | |
2376 | (:count . ,count) | |
2377 | (:longest . ,max) | |
2378 | (:shortest . ,min) | |
2379 | (:flags . 0) | |
2380 | (:delim . ,delim) | |
2381 | (:offset . ,(mapcar (lambda (o) | |
2382 | (list (cons :foo o))) | |
2383 | (nreverse offsets))))))) | |
377ddd88 RS |
2384 | (let ((coding-system-for-write 'raw-text-unix)) |
2385 | (write-file (or index (concat cookies ".dat"))))))) | |
2386 | @end lisp | |
2387 | ||
2388 | Following is an example of defining and unpacking a complex structure. | |
2389 | Consider the following C structures: | |
2390 | ||
2391 | @example | |
2392 | struct header @{ | |
2393 | unsigned long dest_ip; | |
2394 | unsigned long src_ip; | |
2395 | unsigned short dest_port; | |
2396 | unsigned short src_port; | |
2397 | @}; | |
2398 | ||
2399 | struct data @{ | |
2400 | unsigned char type; | |
2401 | unsigned char opcode; | |
2402 | unsigned long length; /* In little endian order */ | |
3f7fab24 | 2403 | unsigned char id[8]; /* null-terminated string */ |
377ddd88 RS |
2404 | unsigned char data[/* (length + 3) & ~3 */]; |
2405 | @}; | |
2406 | ||
2407 | struct packet @{ | |
2408 | struct header header; | |
2409 | unsigned char items; | |
2410 | unsigned char filler[3]; | |
2411 | struct data item[/* items */]; | |
2412 | ||
2413 | @}; | |
2414 | @end example | |
2415 | ||
2416 | The corresponding data layout specification: | |
2417 | ||
2418 | @lisp | |
2419 | (setq header-spec | |
2420 | '((dest-ip ip) | |
2421 | (src-ip ip) | |
2422 | (dest-port u16) | |
2423 | (src-port u16))) | |
2424 | ||
2425 | (setq data-spec | |
2426 | '((type u8) | |
2427 | (opcode u8) | |
2428 | (length u16r) ;; little endian order | |
2429 | (id strz 8) | |
2430 | (data vec (length)) | |
2431 | (align 4))) | |
2432 | ||
2433 | (setq packet-spec | |
2434 | '((header struct header-spec) | |
2435 | (items u8) | |
2436 | (fill 3) | |
2437 | (item repeat (items) | |
2438 | (struct data-spec)))) | |
2439 | @end lisp | |
2440 | ||
2441 | A binary data representation: | |
2442 | ||
2443 | @lisp | |
2444 | (setq binary-data | |
2445 | [ 192 168 1 100 192 168 1 101 01 28 21 32 2 0 0 0 | |
2446 | 2 3 5 0 ?A ?B ?C ?D ?E ?F 0 0 1 2 3 4 5 0 0 0 | |
2447 | 1 4 7 0 ?B ?C ?D ?E ?F ?G 0 0 6 7 8 9 10 11 12 0 ]) | |
2448 | @end lisp | |
2449 | ||
2450 | The corresponding decoded structure: | |
2451 | ||
2452 | @lisp | |
342fd6cd | 2453 | (setq decoded (bindat-unpack packet-spec binary-data)) |
377ddd88 RS |
2454 | @result{} |
2455 | ((header | |
2456 | (dest-ip . [192 168 1 100]) | |
2457 | (src-ip . [192 168 1 101]) | |
2458 | (dest-port . 284) | |
2459 | (src-port . 5408)) | |
2460 | (items . 2) | |
2461 | (item ((data . [1 2 3 4 5]) | |
2462 | (id . "ABCDEF") | |
2463 | (length . 5) | |
2464 | (opcode . 3) | |
2465 | (type . 2)) | |
2466 | ((data . [6 7 8 9 10 11 12]) | |
2467 | (id . "BCDEFG") | |
2468 | (length . 7) | |
2469 | (opcode . 4) | |
2470 | (type . 1)))) | |
2471 | @end lisp | |
2472 | ||
2473 | Fetching data from this structure: | |
2474 | ||
2475 | @lisp | |
342fd6cd | 2476 | (bindat-get-field decoded 'item 1 'id) |
377ddd88 RS |
2477 | @result{} "BCDEFG" |
2478 | @end lisp | |
2479 | ||
ab5796a9 MB |
2480 | @ignore |
2481 | arch-tag: ba9da253-e65f-4e7f-b727-08fba0a1df7a | |
2482 | @end ignore |