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 3 of the License, or
   7    (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17 #include <config.h>
  18
  19
  20 #include <errno.h>
  21 #ifndef errno
  22 extern int errno;
  23 #endif
  24
  25
  26 #if defined _MSC_VER || defined __MINGW32__
  27 /* Native Woe32 API.  */
  28 #include <process.h>
  29 #else
  30 /* Unix API.  */
  31 #include "wait.h"
  32 #endif
  33
  34 #define WAITPID_CHILDREN 8
  35 static pid_t waited_pid[WAITPID_CHILDREN];
  36 static int waited_status[WAITPID_CHILDREN];
  37
  38 pid_t
  39 waitpid (pid_t pid, int *stat_loc, int options)
  40 {
  41   int i;
  42   pid_t p;
  43
  44   if (!options && (pid == -1 || 0 < pid))
  45     {
  46       /* If we have already waited for this child, return it immediately.  */
  47       for (i = 0;  i < WAITPID_CHILDREN;  i++)
  48         {
  49           p = waited_pid[i];
  50           if (p && (p == pid || pid == -1))
  51             {
  52               waited_pid[i] = 0;
  53               goto success;
  54             }
  55         }
  56
  57       /* The child has not returned yet; wait for it, accumulating status.  */
  58       for (i = 0;  i < WAITPID_CHILDREN;  i++)
  59         if (! waited_pid[i])
  60           {
  61             p = wait (&waited_status[i]);
  62             if (p < 0)
  63               return p;
  64             if (p == pid || pid == -1)
  65               goto success;
  66             waited_pid[i] = p;
  67           }
  68     }
  69
  70   /* We cannot emulate this wait call, e.g. because of too many children.  */
  71   errno = EINVAL;
  72   return -1;
  73
  74 success:
  75   if (stat_loc)
  76     *stat_loc = waited_status[i];
  77   return p;
  78 }