lib/waitpid.c

   1 /* Emulate waitpid on systems that just have wait.
   2    Copyright 1994, 1995, 1998, 1999 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; see the file COPYING.
  16    If not, write to the Free Software Foundation,
  17    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 #include <config.h>
  20
  21
  22 #include <errno.h>
  23 #ifndef errno
  24 extern int errno;
  25 #endif
  26
  27
  28 #if defined _MSC_VER || defined __MINGW32__
  29 /* Native Woe32 API.  */
  30 #include <process.h>
  31 #else
  32 /* Unix API.  */
  33 #include "wait.h"
  34 #endif
  35
  36 #define WAITPID_CHILDREN 8
  37 static pid_t waited_pid[WAITPID_CHILDREN];
  38 static int waited_status[WAITPID_CHILDREN];
  39
  40 pid_t
  41 waitpid (pid_t pid, int *stat_loc, int options)
  42 {
  43   int i;
  44   pid_t p;
  45
  46   if (!options && (pid == -1 || 0 < pid))
  47     {
  48       /* If we have already waited for this child, return it immediately.  */
  49       for (i = 0;  i < WAITPID_CHILDREN;  i++)
  50         {
  51           p = waited_pid[i];
  52           if (p && (p == pid || pid == -1))
  53             {
  54               waited_pid[i] = 0;
  55               goto success;
  56             }
  57         }
  58
  59       /* The child has not returned yet; wait for it, accumulating status.  */
  60       for (i = 0;  i < WAITPID_CHILDREN;  i++)
  61         if (! waited_pid[i])
  62           {
  63             p = wait (&waited_status[i]);
  64             if (p < 0)
  65               return p;
  66             if (p == pid || pid == -1)
  67               goto success;
  68             waited_pid[i] = p;
  69           }
  70     }
  71
  72   /* We cannot emulate this wait call, e.g. because of too many children.  */
  73   errno = EINVAL;
  74   return -1;
  75
  76 success:
  77   if (stat_loc)
  78     *stat_loc = waited_status[i];
  79   return p;
  80 }