gnu/dist/gettext/gettext-tools/lib/wait-process.c

   1 /* Waiting for a subprocess to finish.
   2    Copyright (C) 2001-2003 Free Software Foundation, Inc.
   3    Written by Bruno Haible <haible@clisp.cons.org>, 2001.
   4
   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)
   8    any later version.
   9
  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.
  14
  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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  18
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include "config.h"
  22 #endif
  23
  24 /* Specification.  */
  25 #include "wait-process.h"
  26
  27 #include <errno.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30 #include <signal.h>
  31
  32 #include <sys/types.h>
  33
  34 #if defined _MSC_VER || defined __MINGW32__
  35
  36 /* Native Woe32 API.  */
  37 #include <process.h>
  38 #define waitpid(pid,statusp,options) _cwait (statusp, pid, WAIT_CHILD)
  39 #define WAIT_T int
  40 #define WTERMSIG(x) ((x) & 0xff) /* or: SIGABRT ?? */
  41 #define WCOREDUMP(x) 0
  42 #define WEXITSTATUS(x) (((x) >> 8) & 0xff) /* or: (x) ?? */
  43 #define WIFSIGNALED(x) (WTERMSIG (x) != 0) /* or: ((x) == 3) ?? */
  44 #define WIFEXITED(x) (WTERMSIG (x) == 0) /* or: ((x) != 3) ?? */
  45 #define WIFSTOPPED(x) 0
  46
  47 #else
  48
  49 /* Unix API.  */
  50 #include <sys/wait.h>
  51 /* On Linux, WEXITSTATUS are bits 15..8 and WTERMSIG are bits 7..0, while
  52    BeOS uses the contrary.  Therefore we use the abstract macros.  */
  53 #if HAVE_UNION_WAIT
  54 # define WAIT_T union wait
  55 # ifndef WTERMSIG
  56 #  define WTERMSIG(x) ((x).w_termsig)
  57 # endif
  58 # ifndef WCOREDUMP
  59 #  define WCOREDUMP(x) ((x).w_coredump)
  60 # endif
  61 # ifndef WEXITSTATUS
  62 #  define WEXITSTATUS(x) ((x).w_retcode)
  63 # endif
  64 #else
  65 # define WAIT_T int
  66 # ifndef WTERMSIG
  67 #  define WTERMSIG(x) ((x) & 0x7f)
  68 # endif
  69 # ifndef WCOREDUMP
  70 #  define WCOREDUMP(x) ((x) & 0x80)
  71 # endif
  72 # ifndef WEXITSTATUS
  73 #  define WEXITSTATUS(x) (((x) >> 8) & 0xff)
  74 # endif
  75 #endif
  76 /* For valid x, exactly one of WIFSIGNALED(x), WIFEXITED(x), WIFSTOPPED(x)
  77    is true.  */
  78 #ifndef WIFSIGNALED
  79 # define WIFSIGNALED(x) (WTERMSIG (x) != 0 && WTERMSIG(x) != 0x7f)
  80 #endif
  81 #ifndef WIFEXITED
  82 # define WIFEXITED(x) (WTERMSIG (x) == 0)
  83 #endif
  84 #ifndef WIFSTOPPED
  85 # define WIFSTOPPED(x) (WTERMSIG (x) == 0x7f)
  86 #endif
  87 /* Note that portable applications may access
  88    WTERMSIG(x) only if WIFSIGNALED(x) is true, and
  89    WEXITSTATUS(x) only if WIFEXITED(x) is true.  */
  90
  91 #endif
  92
  93 #include "error.h"
  94 #include "exit.h"
  95 #include "fatal-signal.h"
  96 #include "xalloc.h"
  97 #include "gettext.h"
  98
  99 #define _(str) gettext (str)
 100
 101 #define SIZEOF(a) (sizeof(a) / sizeof(a[0]))
 102
 103
 104 #if defined _MSC_VER || defined __MINGW32__
 105
 106 #define WIN32_LEAN_AND_MEAN
 107 #include <windows.h>
 108
 109 /* The return value of spawnvp() is really a process handle as returned
 110    by CreateProcess().  Therefore we can kill it using TerminateProcess.  */
 111 #define kill(pid,sig) TerminateProcess ((HANDLE) (pid), sig)
 112
 113 #endif
 114
 115
 116 /* Type of an entry in the slaves array.
 117    The 'used' bit determines whether this entry is currently in use.
 118    (If pid_t was an atomic type like sig_atomic_t, we could just set the
 119    'child' field to 0 when unregistering a slave process, and wouldn't need
 120    the 'used' field.)
 121    The 'used' and 'child' fields are accessed from within the cleanup_slaves()
 122    action, therefore we mark them as 'volatile'.  */
 123 typedef struct
 124 {
 125   volatile sig_atomic_t used;
 126   volatile pid_t child;
 127 }
 128 slaves_entry_t;
 129
 130 /* The registered slave subprocesses.  */
 131 static slaves_entry_t static_slaves[32];
 132 static slaves_entry_t * volatile slaves = static_slaves;
 133 static sig_atomic_t volatile slaves_count = 0;
 134 static size_t slaves_allocated = SIZEOF (static_slaves);
 135
 136 /* The termination signal for slave subprocesses.
 137    2003-10-07:  Terminator becomes Governator.  */
 138 #ifdef SIGHUP
 139 # define TERMINATOR SIGHUP
 140 #else
 141 # define TERMINATOR SIGTERM
 142 #endif
 143
 144 /* The cleanup action.  It gets called asynchronously.  */
 145 static void
 146 cleanup_slaves (void)
 147 {
 148   for (;;)
 149     {
 150       /* Get the last registered slave.  */
 151       size_t n = slaves_count;
 152       if (n == 0)
 153         break;
 154       n--;
 155       slaves_count = n;
 156       /* Skip unused entries in the slaves array.  */
 157       if (slaves[n].used)
 158         {
 159           pid_t slave = slaves[n].child;
 160
 161           /* Kill the slave.  */
 162           kill (slave, TERMINATOR);
 163         }
 164     }
 165 }
 166
 167 /* Register a subprocess as being a slave process.  This means that the
 168    subprocess will be terminated when its creator receives a catchable fatal
 169    signal or exits normally.  Registration ends when wait_subprocess()
 170    notices that the subprocess has exited.  */
 171 void
 172 register_slave_subprocess (pid_t child)
 173 {
 174   static bool cleanup_slaves_registered = false;
 175   if (!cleanup_slaves_registered)
 176     {
 177       atexit (cleanup_slaves);
 178       at_fatal_signal (cleanup_slaves);
 179       cleanup_slaves_registered = true;
 180     }
 181
 182   /* Try to store the new slave in an unused entry of the slaves array.  */
 183   {
 184     slaves_entry_t *s = slaves;
 185     slaves_entry_t *s_end = s + slaves_count;
 186
 187     for (; s < s_end; s++)
 188       if (!s->used)
 189         {
 190           /* The two uses of 'volatile' in the slaves_entry_t type above
 191              (and ISO C 99 section 5.1.2.3.(5)) ensure that we mark the
 192              entry as used only after the child pid has been written to the
 193              memory location s->child.  */
 194           s->child = child;
 195           s->used = 1;
 196           return;
 197         }
 198   }
 199
 200   if (slaves_count == slaves_allocated)
 201     {
 202       /* Extend the slaves array.  Note that we cannot use xrealloc(),
 203          because then the cleanup_slaves() function could access an already
 204          deallocated array.  */
 205       slaves_entry_t *old_slaves = slaves;
 206       size_t new_slaves_allocated = 2 * slaves_allocated;
 207       slaves_entry_t *new_slaves =
 208         malloc (new_slaves_allocated * sizeof (slaves_entry_t));
 209       if (new_slaves == NULL)
 210         {
 211           /* xalloc_die() will call exit() which will invoke cleanup_slaves().
 212              Additionally we need to kill child, because it's not yet among
 213              the slaves list.  */
 214           kill (child, TERMINATOR);
 215           xalloc_die ();
 216         }
 217       memcpy (new_slaves, old_slaves,
 218               slaves_allocated * sizeof (slaves_entry_t));
 219       slaves = new_slaves;
 220       slaves_allocated = new_slaves_allocated;
 221       /* Now we can free the old slaves array.  */
 222       if (old_slaves != static_slaves)
 223         free (old_slaves);
 224     }
 225   /* The three uses of 'volatile' in the types above (and ISO C 99 section
 226      5.1.2.3.(5)) ensure that we increment the slaves_count only after the
 227      new slave and its 'used' bit have been written to the memory locations
 228      that make up slaves[slaves_count].  */
 229   slaves[slaves_count].child = child;
 230   slaves[slaves_count].used = 1;
 231   slaves_count++;
 232 }
 233
 234 /* Unregister a child from the list of slave subprocesses.  */
 235 static inline void
 236 unregister_slave_subprocess (pid_t child)
 237 {
 238   /* The easiest way to remove an entry from a list that can be used by
 239      an asynchronous signal handler is just to mark it as unused.  For this,
 240      we rely on sig_atomic_t.  */
 241   slaves_entry_t *s = slaves;
 242   slaves_entry_t *s_end = s + slaves_count;
 243
 244   for (; s < s_end; s++)
 245     if (s->used && s->child == child)
 246       s->used = 0;
 247 }
 248
 249
 250 /* Wait for a subprocess to finish.  Return its exit code.
 251    If it didn't terminate correctly, exit if exit_on_error is true, otherwise
 252    return 127.  */
 253 int
 254 wait_subprocess (pid_t child, const char *progname,
 255                  bool ignore_sigpipe, bool null_stderr,
 256                  bool slave_process, bool exit_on_error)
 257 {
 258 #if HAVE_WAITID && defined WNOWAIT && 0
 259   /* Commented out because waitid() with WNOWAIT doesn't work: On Solaris 7
 260      and OSF/1 4.0, it returns -1 and sets errno = ECHILD, and on HP-UX 10.20
 261      it just hangs.  */
 262   /* Use of waitid() with WNOWAIT avoids a race condition: If slave_process is
 263      true, and this process sleeps a very long time between the return from
 264      waitpid() and the execution of unregister_slave_subprocess(), and
 265      meanwhile another process acquires the same PID as child, and then - still
 266      before unregister_slave_subprocess() - this process gets a fatal signal,
 267      it would kill the other totally unrelated process.  */
 268   siginfo_t info;
 269   for (;;)
 270     {
 271       if (waitid (P_PID, child, &info, slave_process ? WNOWAIT : 0) < 0)
 272         {
 273 # ifdef EINTR
 274           if (errno == EINTR)
 275             continue;
 276 # endif
 277           if (exit_on_error || !null_stderr)
 278             error (exit_on_error ? EXIT_FAILURE : 0, errno,
 279                    _("%s subprocess"), progname);
 280           return 127;
 281         }
 282
 283       /* info.si_code is set to one of CLD_EXITED, CLD_KILLED, CLD_DUMPED,
 284          CLD_TRAPPED, CLD_STOPPED, CLD_CONTINUED.  Loop until the program
 285          terminates.  */
 286       if (info.si_code == CLD_EXITED
 287           || info.si_code == CLD_KILLED || info.si_code == CLD_DUMPED)
 288         break;
 289     }
 290
 291   /* The child process has exited or was signalled.  */
 292
 293   if (slave_process)
 294     {
 295       /* Unregister the child from the list of slave subprocesses, so that
 296          later, when we exit, we don't kill a totally unrelated process which
 297          may have acquired the same pid.  */
 298       unregister_slave_subprocess (child);
 299
 300       /* Now remove the zombie from the process list.  */
 301       for (;;)
 302         {
 303           if (waitid (P_PID, child, &info, 0) < 0)
 304             {
 305 # ifdef EINTR
 306               if (errno == EINTR)
 307                 continue;
 308 # endif
 309               if (exit_on_error || !null_stderr)
 310                 error (exit_on_error ? EXIT_FAILURE : 0, errno,
 311                        _("%s subprocess"), progname);
 312               return 127;
 313             }
 314           break;
 315         }
 316     }
 317
 318   switch (info.si_code)
 319     {
 320     case CLD_KILLED:
 321     case CLD_DUMPED:
 322 # ifdef SIGPIPE
 323       if (info.si_status == SIGPIPE && ignore_sigpipe)
 324         return 0;
 325 # endif
 326       if (exit_on_error || !null_stderr)
 327         error (exit_on_error ? EXIT_FAILURE : 0, 0,
 328                _("%s subprocess got fatal signal %d"),
 329                progname, info.si_status);
 330       return 127;
 331     case CLD_EXITED:
 332       if (info.si_status == 127)
 333         {
 334           if (exit_on_error || !null_stderr)
 335             error (exit_on_error ? EXIT_FAILURE : 0, 0,
 336                    _("%s subprocess failed"), progname);
 337           return 127;
 338         }
 339       return info.si_status;
 340     default:
 341       abort ();
 342     }
 343 #else
 344   /* waitpid() is just as portable as wait() nowadays.  */
 345   WAIT_T status;
 346
 347   *(int *) &status = 0;
 348   for (;;)
 349     {
 350       int result = waitpid (child, &status, 0);
 351
 352       if (result != child)
 353         {
 354 # ifdef EINTR
 355           if (errno == EINTR)
 356             continue;
 357 # endif
 358 # if 0 /* defined ECHILD */
 359           if (errno == ECHILD)
 360             {
 361               /* Child process nonexistent?! Assume it terminated
 362                  successfully.  */
 363               *(int *) &status = 0;
 364               break;
 365             }
 366 # endif
 367           if (exit_on_error || !null_stderr)
 368             error (exit_on_error ? EXIT_FAILURE : 0, errno,
 369                    _("%s subprocess"), progname);
 370           return 127;
 371         }
 372
 373       /* One of WIFSIGNALED (status), WIFEXITED (status), WIFSTOPPED (status)
 374          must always be true.  Loop until the program terminates.  */
 375       if (!WIFSTOPPED (status))
 376         break;
 377     }
 378
 379   /* The child process has exited or was signalled.  */
 380
 381   if (slave_process)
 382     /* Unregister the child from the list of slave subprocesses, so that
 383        later, when we exit, we don't kill a totally unrelated process which
 384        may have acquired the same pid.  */
 385     unregister_slave_subprocess (child);
 386
 387   if (WIFSIGNALED (status))
 388     {
 389 # ifdef SIGPIPE
 390       if (WTERMSIG (status) == SIGPIPE && ignore_sigpipe)
 391         return 0;
 392 # endif
 393       if (exit_on_error || !null_stderr)
 394         error (exit_on_error ? EXIT_FAILURE : 0, 0,
 395                _("%s subprocess got fatal signal %d"),
 396                progname, (int) WTERMSIG (status));
 397       return 127;
 398     }
 399   if (WEXITSTATUS (status) == 127)
 400     {
 401       if (exit_on_error || !null_stderr)
 402         error (exit_on_error ? EXIT_FAILURE : 0, 0,
 403                _("%s subprocess failed"), progname);
 404       return 127;
 405     }
 406   return WEXITSTATUS (status);
 407 #endif
 408 }