1 /* Copyright (C) 1989, 1990, 1991, 1992, 2000, 2002
2 * Free Software Foundation, Inc.
3 * Copyright (C) 2003, 2004, 2005, 2007, 2008 Colin Watson.
4 * Written for groff by James Clark (jjc@jclark.com)
5 * Adapted for man-db by Colin Watson.
7 * This file is part of libpipeline.
9 * libpipeline is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or (at
12 * your option) any later version.
14 * libpipeline is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with libpipeline; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
34 #include <sys/types.h>
36 /* GCC version checking borrowed from glibc. */
37 #if defined(__GNUC__) && defined(__GNUC_MINOR__)
38 # define PIPELINE_GNUC_PREREQ(maj,min) \
39 ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
41 # define PIPELINE_GNUC_PREREQ(maj,min) 0
44 /* Does this compiler support format string checking? */
45 #if PIPELINE_GNUC_PREREQ(2,0)
46 # define PIPELINE_ATTR_FORMAT_PRINTF(a,b) \
47 __attribute__ ((__format__ (__printf__, a, b)))
49 # define PIPELINE_ATTR_FORMAT_PRINTF(a,b)
52 /* Does this compiler support marking variables as unused? */
53 #if PIPELINE_GNUC_PREREQ(2,4)
54 # define PIPELINE_ATTR_UNUSED __attribute__ ((__unused__))
56 # define PIPELINE_ATTR_UNUSED
59 /* Does this compiler support marking functions as non-returning? */
60 #if PIPELINE_GNUC_PREREQ(2,5)
61 # define PIPELINE_ATTR_NORETURN __attribute__ ((__noreturn__))
63 # define PIPELINE_ATTR_NORETURN
66 /* Does this compiler support unused result checking? */
67 #if PIPELINE_GNUC_PREREQ(3,4)
68 # define PIPELINE_ATTR_WARN_UNUSED_RESULT \
69 __attribute__ ((__warn_unused_result__))
71 # define PIPELINE_ATTR_WARN_UNUSED_RESULT
74 /* Does this compiler support sentinel checking? */
75 #if PIPELINE_GNUC_PREREQ(4,0)
76 # define PIPELINE_ATTR_SENTINEL __attribute__ ((__sentinel__))
78 # define PIPELINE_ATTR_SENTINEL
81 typedef void pipecmd_function_type (void *);
82 typedef void pipecmd_function_free_type (void *);
85 typedef struct pipecmd pipecmd;
88 typedef struct pipeline pipeline;
90 /* ---------------------------------------------------------------------- */
92 /* Functions to build individual commands. */
94 /* Construct a new command. */
95 pipecmd *pipecmd_new (const char *name);
97 /* Convenience constructors wrapping pipecmd_new() and pipecmd_arg().
98 * Terminate arguments with NULL.
100 pipecmd *pipecmd_new_argv (const char *name, va_list argv);
101 pipecmd *pipecmd_new_args (const char *name, ...) PIPELINE_ATTR_SENTINEL;
103 /* Split argstr on whitespace to construct a command and arguments,
104 * honouring shell-style single-quoting, double-quoting, and backslashes,
105 * but not other shell evil like wildcards, semicolons, or backquotes. This
106 * is a backward-compatibility hack to support old configuration file
107 * directives; please try to avoid using it in new code.
109 pipecmd *pipecmd_new_argstr (const char *argstr);
111 /* Construct a new command that calls a given function rather than executing
112 * a process. The data argument is passed as the function's only argument,
113 * and will be freed before returning using free_func (if non-NULL).
115 * pipecmd_* functions that deal with arguments cannot be used with the
116 * command returned by this function.
118 pipecmd *pipecmd_new_function (const char *name,
119 pipecmd_function_type *func,
120 pipecmd_function_free_type *free_func,
123 /* Construct a new command that runs a sequence of commands. The commands
124 * will be executed in forked children; if any exits non-zero then it will
125 * terminate the sequence, as with "&&" in shell.
127 * pipecmd_* functions that deal with arguments cannot be used with the
128 * command returned by this function.
130 pipecmd *pipecmd_new_sequencev (const char *name, va_list cmdv);
131 pipecmd *pipecmd_new_sequence (const char *name, ...) PIPELINE_ATTR_SENTINEL;
133 /* Return a new command that just passes data from its input to its output. */
134 pipecmd *pipecmd_new_passthrough (void);
136 /* Return a duplicate of a command. */
137 pipecmd *pipecmd_dup (pipecmd *cmd);
139 /* Add an argument to a command. */
140 void pipecmd_arg (pipecmd *cmd, const char *arg);
142 /* Convenience function to add an argument with printf substitutions. */
143 void pipecmd_argf (pipecmd *cmd, const char *format, ...)
144 PIPELINE_ATTR_FORMAT_PRINTF(2, 3);
146 /* Convenience functions wrapping pipecmd_arg().
147 * Terminate arguments with NULL.
149 void pipecmd_argv (pipecmd *cmd, va_list argv);
150 void pipecmd_args (pipecmd *cmd, ...) PIPELINE_ATTR_SENTINEL;
152 /* Split argstr on whitespace to add a list of arguments, honouring
153 * shell-style single-quoting, double-quoting, and backslashes, but not
154 * other shell evil like wildcards, semicolons, or backquotes. This is a
155 * backward-compatibility hack to support old configuration file directives;
156 * please try to avoid using it in new code.
158 void pipecmd_argstr (pipecmd *cmd, const char *argstr);
160 /* Return the number of arguments to this command. Note that this includes
161 * the command name as the first argument, so the command 'echo foo bar' is
162 * counted as having three arguments.
164 int pipecmd_get_nargs (pipecmd *cmd);
166 /* Set the nice(3) value for this command. Defaults to 0. Errors while
167 * attempting to set the nice value are ignored, aside from emitting a debug
170 void pipecmd_nice (pipecmd *cmd, int nice);
172 /* If discard_err is non-zero, redirect this command's standard error to
173 * /dev/null. Otherwise, and by default, pass it through.
175 void pipecmd_discard_err (pipecmd *cmd, int discard_err);
177 /* Set an environment variable while running this command. */
178 void pipecmd_setenv (pipecmd *cmd, const char *name, const char *value);
180 /* Unset an environment variable while running this command. */
181 void pipecmd_unsetenv (pipecmd *cmd, const char *name);
183 /* Clear the environment while running this command. (Note that environment
184 * operations work in sequence; pipecmd_clearenv followed by pipecmd_setenv
185 * causes the command to have just a single environment variable set.)
187 void pipecmd_clearenv (pipecmd *cmd);
189 /* Add a command to a sequence. */
190 void pipecmd_sequence_command (pipecmd *cmd, pipecmd *child);
192 /* Dump a string representation of a command to stream. */
193 void pipecmd_dump (pipecmd *cmd, FILE *stream);
195 /* Return a string representation of a command. The caller should free the
198 char *pipecmd_tostring (pipecmd *cmd);
200 /* Execute a single command, replacing the current process. Never returns,
201 * instead exiting non-zero on failure.
203 void pipecmd_exec (pipecmd *cmd) PIPELINE_ATTR_NORETURN;
205 /* Destroy a command. Safely does nothing on NULL. */
206 void pipecmd_free (pipecmd *cmd);
208 /* ---------------------------------------------------------------------- */
210 /* Functions to build pipelines. */
212 /* Construct a new pipeline. */
213 pipeline *pipeline_new (void);
215 /* Convenience constructors wrapping pipeline_new() and pipeline_command().
216 * Terminate commands with NULL.
218 pipeline *pipeline_new_commandv (pipecmd *cmd1, va_list cmdv);
219 pipeline *pipeline_new_commands (pipecmd *cmd1, ...) PIPELINE_ATTR_SENTINEL;
221 /* Construct a new pipeline and add a single command to it. */
222 pipeline *pipeline_new_command_argv (const char *name, va_list argv);
223 pipeline *pipeline_new_command_args (const char *name, ...)
224 PIPELINE_ATTR_SENTINEL;
226 /* Joins two pipelines, neither of which are allowed to be started. Discards
227 * want_out, want_outfile, and outfd from p1, and want_in, want_infile, and
230 pipeline *pipeline_join (pipeline *p1, pipeline *p2);
232 /* Connect the input of one or more sink pipelines to the output of a source
233 * pipeline. The source pipeline may be started, but in that case want_out
234 * must be negative; otherwise, discards want_out from source. In any event,
235 * discards want_in from all sinks, none of which are allowed to be started.
236 * Terminate arguments with NULL.
238 * This is an application-level connection; data may be intercepted between
239 * the pipelines by the program before calling pipeline_pump(), which sets
240 * data flowing from the source to the sinks. It is primarily useful when
241 * more than one sink pipeline is involved, in which case the pipelines
242 * cannot simply be concatenated into one.
244 void pipeline_connect (pipeline *source, pipeline *sink, ...)
245 PIPELINE_ATTR_SENTINEL;
247 /* Add a command to a pipeline. */
248 void pipeline_command (pipeline *p, pipecmd *cmd);
250 /* Construct a new command and add it to a pipeline in one go. */
251 void pipeline_command_argv (pipeline *p, const char *name, va_list argv);
252 void pipeline_command_args (pipeline *p, const char *name, ...)
253 PIPELINE_ATTR_SENTINEL;
255 /* Construct a new command from a shell-quoted string and add it to a
256 * pipeline in one go. See the comment against pipecmd_new_argstr() above if
257 * you're tempted to use this function.
259 void pipeline_command_argstr (pipeline *p, const char *argstr);
261 /* Convenience functions wrapping pipeline_command().
262 * Terminate commands with NULL.
264 void pipeline_commandv (pipeline *p, va_list cmdv);
265 void pipeline_commands (pipeline *p, ...) PIPELINE_ATTR_SENTINEL;
267 /* Return the number of commands in this pipeline. */
268 int pipeline_get_ncommands (pipeline *p);
270 /* Return command number n from this pipeline, counting from zero, or NULL
271 * if n is out of range.
273 pipecmd *pipeline_get_command (pipeline *p, int n);
275 /* Set command number n in this pipeline, counting from zero, to cmd, and
276 * return the previous command in that position. Do nothing and return NULL
277 * if n is out of range.
279 pipecmd *pipeline_set_command (pipeline *p, int n, pipecmd *cmd);
281 /* Return the process ID of command number n from this pipeline, counting
282 * from zero. The pipeline must be started. Return -1 if n is out of range
283 * or if the command has already exited and been reaped.
285 pid_t pipeline_get_pid (pipeline *p, int n);
287 /* Set file descriptors to use as the input and output of the whole
288 * pipeline. If non-negative, fd is used directly as a file descriptor. If
289 * negative, pipeline_start will create pipes and store the input writing
290 * half and the output reading half in the pipeline's infd or outfd field as
291 * appropriate. The default is to leave input and output as stdin and
292 * stdout unless pipeline_want_infile or pipeline_want_outfile respectively
295 * Calling these functions supersedes any previous call to
296 * pipeline_want_infile or pipeline_want_outfile respectively.
298 void pipeline_want_in (pipeline *p, int fd);
299 void pipeline_want_out (pipeline *p, int fd);
301 /* Set file names to open and use as the input and output of the whole
302 * pipeline. This may be more convenient than supplying file descriptors,
303 * and guarantees that the files are opened with the same privileges under
304 * which the pipeline is run.
306 * Calling these functions (even with NULL, which returns to the default of
307 * leaving input and output as stdin and stdout) supersedes any previous
308 * call to pipeline_want_in or pipeline_want_outfile respectively.
310 * The given files will be opened when the pipeline is started. If an
311 * output file does not already exist, it is created (with mode 0666
312 * modified in the usual way by umask); if it does exist, then it is
315 void pipeline_want_infile (pipeline *p, const char *file);
316 void pipeline_want_outfile (pipeline *p, const char *file);
318 /* If ignore_signals is non-zero (which is the default), ignore SIGINT and
319 * SIGQUIT while the pipeline is running, like system(). Otherwise, leave
320 * their dispositions unchanged.
322 void pipeline_ignore_signals (pipeline *p, int ignore_signals);
324 /* Get streams corresponding to infd and outfd respectively. The pipeline
327 FILE *pipeline_get_infile (pipeline *p);
328 FILE *pipeline_get_outfile (pipeline *p);
330 /* Dump a string representation of p to stream. */
331 void pipeline_dump (pipeline *p, FILE *stream);
333 /* Return a string representation of p. The caller should free the result. */
334 char *pipeline_tostring (pipeline *p);
336 /* Destroy a pipeline and all its commands. Safely does nothing on NULL.
337 * May wait for the pipeline to complete if it has not already done so.
339 void pipeline_free (pipeline *p);
341 /* ---------------------------------------------------------------------- */
343 /* Functions to run pipelines and handle signals. */
345 typedef void pipeline_post_fork_fn (void);
347 /* Install a post-fork handler. This will be run in any child process
348 * immediately after it is forked. For instance, this may be used for
349 * cleaning up application-specific signal handlers. Pass NULL to clear any
350 * existing post-fork handler.
352 void pipeline_install_post_fork (pipeline_post_fork_fn *fn);
354 /* Start the processes in a pipeline. Installs this library's SIGCHLD
355 * handler if not already installed. Calls error(FATAL) on error. */
356 void pipeline_start (pipeline *p);
358 /* Wait for a pipeline to complete. Set *statuses to a newly-allocated
359 * array of wait statuses, as returned by waitpid, and *n_statuses to the
360 * length of that array. The return value is similar to the exit status
361 * that a shell would return, with some modifications. If the last command
362 * exits with a signal (other than SIGPIPE, which is considered equivalent
363 * to exiting zero), then the return value is 128 plus the signal number; if
364 * the last command exits normally but non-zero, then the return value is
365 * its exit status; if any other command exits non-zero, then the return
366 * value is 127; otherwise, the return value is 0. This means that the
367 * return value is only 0 if all commands in the pipeline exit successfully.
369 int pipeline_wait_all (pipeline *p, int **statuses, int *n_statuses);
371 /* Wait for a pipeline to complete and return its combined exit status,
372 * calculated as for pipeline_wait_all().
374 int pipeline_wait (pipeline *p);
376 /* Start a pipeline, wait for it to complete, and free it, all in one go. */
377 int pipeline_run (pipeline *p);
379 /* Pump data among one or more pipelines connected using pipeline_connect()
380 * until all source pipelines have reached end-of-file and all data has been
381 * written to all sinks (or failed). All relevant pipelines must be
382 * supplied: that is, no pipeline that has been connected to a source
383 * pipeline may be supplied unless that source pipeline is also supplied.
384 * Automatically starts all pipelines if they are not already started, but
385 * does not wait for them. Terminate arguments with NULL.
387 void pipeline_pump (pipeline *p, ...) PIPELINE_ATTR_SENTINEL;
389 /* ---------------------------------------------------------------------- */
391 /* Functions to read output from pipelines. */
393 /* Read len bytes of data from the pipeline, returning the data block. len
394 * is updated with the number of bytes read.
396 const char *pipeline_read (pipeline *p, size_t *len);
398 /* Look ahead in the pipeline's output for len bytes of data, returning the
399 * data block. len is updated with the number of bytes read. The starting
400 * position of the next read or peek is not affected by this call.
402 const char *pipeline_peek (pipeline *p, size_t *len);
404 /* Return the number of bytes of data that can be read using pipeline_read
405 * or pipeline_peek solely from the peek cache, without having to read from
406 * the pipeline itself (and thus potentially block).
408 size_t pipeline_peek_size (pipeline *p);
410 /* Skip over and discard len bytes of data from the peek cache. Asserts that
411 * enough data is available to skip, so you may want to check using
412 * pipeline_peek_size first.
414 void pipeline_peek_skip (pipeline *p, size_t len);
416 /* Read a line of data from the pipeline, returning it. */
417 const char *pipeline_readline (pipeline *p);
419 /* Look ahead in the pipeline's output for a line of data, returning it. The
420 * starting position of the next read or peek is not affected by this call.
422 const char *pipeline_peekline (pipeline *p);
428 #endif /* PIPELINE_H */