1/* Emulate waitpid on systems that just have wait.
2   Copyright (C) 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   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
18
19#if HAVE_CONFIG_H
20# include <config.h>
21#endif
22
23#include <sys/types.h>
24#include <errno.h>
25#ifndef errno
26extern int errno;
27#endif
28
29#define WAITPID_CHILDREN 8
30static pid_t waited_pid[WAITPID_CHILDREN];
31static int waited_status[WAITPID_CHILDREN];
32
33pid_t
34waitpid (pid_t pid, int *stat_loc, int options)
35{
36  int i;
37  pid_t p;
38
39  if (!options && (pid == -1 || 0 < pid))
40    {
41      /* If we have already waited for this child, return it immediately.  */
42      for (i = 0;  i < WAITPID_CHILDREN;  i++)
43	{
44	  p = waited_pid[i];
45	  if (p && (p == pid || pid == -1))
46	    {
47	      waited_pid[i] = 0;
48	      goto success;
49	    }
50	}
51
52      /* The child has not returned yet; wait for it, accumulating status.  */
53      for (i = 0;  i < WAITPID_CHILDREN;  i++)
54	if (! waited_pid[i])
55	  {
56	    p = wait (&waited_status[i]);
57	    if (p < 0)
58	      return p;
59	    if (p == pid || pid == -1)
60	      goto success;
61	    waited_pid[i] = p;
62	  }
63    }
64
65  /* We cannot emulate this wait call, e.g. because of too many children.  */
66  errno = EINVAL;
67  return -1;
68
69success:
70  if (stat_loc)
71    *stat_loc = waited_status[i];
72  return p;
73}
74