1 /* Waiting for a subprocess to finish.
2 Copyright (C) 2001-2003, 2005-2007 Free Software Foundation, Inc.
3 Written by Bruno Haible <haible@clisp.cons.org>, 2001.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
23 #include "wait-process.h"
30 #include <sys/types.h>
32 #if defined _MSC_VER || defined __MINGW32__
34 /* Native Woe32 API. */
36 #define waitpid(pid,statusp,options) _cwait (statusp, pid, WAIT_CHILD)
38 #define WTERMSIG(x) ((x) & 0xff) /* or: SIGABRT ?? */
39 #define WCOREDUMP(x) 0
40 #define WEXITSTATUS(x) (((x) >> 8) & 0xff) /* or: (x) ?? */
41 #define WIFSIGNALED(x) (WTERMSIG (x) != 0) /* or: ((x) == 3) ?? */
42 #define WIFEXITED(x) (WTERMSIG (x) == 0) /* or: ((x) != 3) ?? */
43 #define WIFSTOPPED(x) 0
49 /* On Linux, WEXITSTATUS are bits 15..8 and WTERMSIG are bits 7..0, while
50 BeOS uses the contrary. Therefore we use the abstract macros. */
52 # define WAIT_T union wait
54 # define WTERMSIG(x) ((x).w_termsig)
57 # define WCOREDUMP(x) ((x).w_coredump)
60 # define WEXITSTATUS(x) ((x).w_retcode)
65 # define WTERMSIG(x) ((x) & 0x7f)
68 # define WCOREDUMP(x) ((x) & 0x80)
71 # define WEXITSTATUS(x) (((x) >> 8) & 0xff)
74 /* For valid x, exactly one of WIFSIGNALED(x), WIFEXITED(x), WIFSTOPPED(x)
77 # define WIFSIGNALED(x) (WTERMSIG (x) != 0 && WTERMSIG(x) != 0x7f)
80 # define WIFEXITED(x) (WTERMSIG (x) == 0)
83 # define WIFSTOPPED(x) (WTERMSIG (x) == 0x7f)
85 /* Note that portable applications may access
86 WTERMSIG(x) only if WIFSIGNALED(x) is true, and
87 WEXITSTATUS(x) only if WIFEXITED(x) is true. */
92 #include "fatal-signal.h"
96 #define _(str) gettext (str)
98 #define SIZEOF(a) (sizeof(a) / sizeof(a[0]))
101 #if defined _MSC_VER || defined __MINGW32__
103 #define WIN32_LEAN_AND_MEAN
106 /* The return value of spawnvp() is really a process handle as returned
107 by CreateProcess(). Therefore we can kill it using TerminateProcess. */
108 #define kill(pid,sig) TerminateProcess ((HANDLE) (pid), sig)
113 /* Type of an entry in the slaves array.
114 The 'used' bit determines whether this entry is currently in use.
115 (If pid_t was an atomic type like sig_atomic_t, we could just set the
116 'child' field to 0 when unregistering a slave process, and wouldn't need
118 The 'used' and 'child' fields are accessed from within the cleanup_slaves()
119 action, therefore we mark them as 'volatile'. */
122 volatile sig_atomic_t used;
123 volatile pid_t child;
127 /* The registered slave subprocesses. */
128 static slaves_entry_t static_slaves[32];
129 static slaves_entry_t * volatile slaves = static_slaves;
130 static sig_atomic_t volatile slaves_count = 0;
131 static size_t slaves_allocated = SIZEOF (static_slaves);
133 /* The termination signal for slave subprocesses.
134 2003-10-07: Terminator becomes Governator. */
136 # define TERMINATOR SIGHUP
138 # define TERMINATOR SIGTERM
141 /* The cleanup action. It gets called asynchronously. */
143 cleanup_slaves (void)
147 /* Get the last registered slave. */
148 size_t n = slaves_count;
153 /* Skip unused entries in the slaves array. */
156 pid_t slave = slaves[n].child;
158 /* Kill the slave. */
159 kill (slave, TERMINATOR);
164 /* Register a subprocess as being a slave process. This means that the
165 subprocess will be terminated when its creator receives a catchable fatal
166 signal or exits normally. Registration ends when wait_subprocess()
167 notices that the subprocess has exited. */
169 register_slave_subprocess (pid_t child)
171 static bool cleanup_slaves_registered = false;
172 if (!cleanup_slaves_registered)
174 atexit (cleanup_slaves);
175 at_fatal_signal (cleanup_slaves);
176 cleanup_slaves_registered = true;
179 /* Try to store the new slave in an unused entry of the slaves array. */
181 slaves_entry_t *s = slaves;
182 slaves_entry_t *s_end = s + slaves_count;
184 for (; s < s_end; s++)
187 /* The two uses of 'volatile' in the slaves_entry_t type above
188 (and ISO C 99 section 5.1.2.3.(5)) ensure that we mark the
189 entry as used only after the child pid has been written to the
190 memory location s->child. */
197 if (slaves_count == slaves_allocated)
199 /* Extend the slaves array. Note that we cannot use xrealloc(),
200 because then the cleanup_slaves() function could access an already
201 deallocated array. */
202 slaves_entry_t *old_slaves = slaves;
203 size_t new_slaves_allocated = 2 * slaves_allocated;
204 slaves_entry_t *new_slaves =
206 malloc (new_slaves_allocated * sizeof (slaves_entry_t));
207 if (new_slaves == NULL)
209 /* xalloc_die() will call exit() which will invoke cleanup_slaves().
210 Additionally we need to kill child, because it's not yet among
212 kill (child, TERMINATOR);
215 memcpy (new_slaves, old_slaves,
216 slaves_allocated * sizeof (slaves_entry_t));
218 slaves_allocated = new_slaves_allocated;
219 /* Now we can free the old slaves array. */
220 if (old_slaves != static_slaves)
223 /* The three uses of 'volatile' in the types above (and ISO C 99 section
224 5.1.2.3.(5)) ensure that we increment the slaves_count only after the
225 new slave and its 'used' bit have been written to the memory locations
226 that make up slaves[slaves_count]. */
227 slaves[slaves_count].child = child;
228 slaves[slaves_count].used = 1;
232 /* Unregister a child from the list of slave subprocesses. */
234 unregister_slave_subprocess (pid_t child)
236 /* The easiest way to remove an entry from a list that can be used by
237 an asynchronous signal handler is just to mark it as unused. For this,
238 we rely on sig_atomic_t. */
239 slaves_entry_t *s = slaves;
240 slaves_entry_t *s_end = s + slaves_count;
242 for (; s < s_end; s++)
243 if (s->used && s->child == child)
248 /* Wait for a subprocess to finish. Return its exit code.
249 If it didn't terminate correctly, exit if exit_on_error is true, otherwise
252 wait_subprocess (pid_t child, const char *progname,
253 bool ignore_sigpipe, bool null_stderr,
254 bool slave_process, bool exit_on_error)
256 #if HAVE_WAITID && defined WNOWAIT && 0
257 /* Commented out because waitid() with WNOWAIT doesn't work: On Solaris 7
258 and OSF/1 4.0, it returns -1 and sets errno = ECHILD, and on HP-UX 10.20
260 /* Use of waitid() with WNOWAIT avoids a race condition: If slave_process is
261 true, and this process sleeps a very long time between the return from
262 waitpid() and the execution of unregister_slave_subprocess(), and
263 meanwhile another process acquires the same PID as child, and then - still
264 before unregister_slave_subprocess() - this process gets a fatal signal,
265 it would kill the other totally unrelated process. */
269 if (waitid (P_PID, child, &info, slave_process ? WNOWAIT : 0) < 0)
275 if (exit_on_error || !null_stderr)
276 error (exit_on_error ? EXIT_FAILURE : 0, errno,
277 _("%s subprocess"), progname);
281 /* info.si_code is set to one of CLD_EXITED, CLD_KILLED, CLD_DUMPED,
282 CLD_TRAPPED, CLD_STOPPED, CLD_CONTINUED. Loop until the program
284 if (info.si_code == CLD_EXITED
285 || info.si_code == CLD_KILLED || info.si_code == CLD_DUMPED)
289 /* The child process has exited or was signalled. */
293 /* Unregister the child from the list of slave subprocesses, so that
294 later, when we exit, we don't kill a totally unrelated process which
295 may have acquired the same pid. */
296 unregister_slave_subprocess (child);
298 /* Now remove the zombie from the process list. */
301 if (waitid (P_PID, child, &info, 0) < 0)
307 if (exit_on_error || !null_stderr)
308 error (exit_on_error ? EXIT_FAILURE : 0, errno,
309 _("%s subprocess"), progname);
316 switch (info.si_code)
321 if (info.si_status == SIGPIPE && ignore_sigpipe)
324 if (exit_on_error || !null_stderr)
325 error (exit_on_error ? EXIT_FAILURE : 0, 0,
326 _("%s subprocess got fatal signal %d"),
327 progname, info.si_status);
330 if (info.si_status == 127)
332 if (exit_on_error || !null_stderr)
333 error (exit_on_error ? EXIT_FAILURE : 0, 0,
334 _("%s subprocess failed"), progname);
337 return info.si_status;
342 /* waitpid() is just as portable as wait() nowadays. */
345 *(int *) &status = 0;
348 int result = waitpid (child, &status, 0);
356 # if 0 /* defined ECHILD */
359 /* Child process nonexistent?! Assume it terminated
361 *(int *) &status = 0;
365 if (exit_on_error || !null_stderr)
366 error (exit_on_error ? EXIT_FAILURE : 0, errno,
367 _("%s subprocess"), progname);
371 /* One of WIFSIGNALED (status), WIFEXITED (status), WIFSTOPPED (status)
372 must always be true. Loop until the program terminates. */
373 if (!WIFSTOPPED (status))
377 /* The child process has exited or was signalled. */
380 /* Unregister the child from the list of slave subprocesses, so that
381 later, when we exit, we don't kill a totally unrelated process which
382 may have acquired the same pid. */
383 unregister_slave_subprocess (child);
385 if (WIFSIGNALED (status))
388 if (WTERMSIG (status) == SIGPIPE && ignore_sigpipe)
391 if (exit_on_error || !null_stderr)
392 error (exit_on_error ? EXIT_FAILURE : 0, 0,
393 _("%s subprocess got fatal signal %d"),
394 progname, (int) WTERMSIG (status));
397 if (WEXITSTATUS (status) == 127)
399 if (exit_on_error || !null_stderr)
400 error (exit_on_error ? EXIT_FAILURE : 0, 0,
401 _("%s subprocess failed"), progname);
404 return WEXITSTATUS (status);