1/*	$NetBSD: waitpid.c,v 1.1.1.1 2016/01/13 03:15:30 christos Exp $	*/
2
3/* Emulate waitpid on systems that just have wait.
4   Copyright (C) 1994, 1995, 1998, 1999 Free Software Foundation, Inc.
5
6   This program is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 2, or (at your option)
9   any later version.
10
11   This program is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with this program; see the file COPYING.
18   If not, write to the Free Software Foundation,
19   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
20
21#if HAVE_CONFIG_H
22# include <config.h>
23#endif
24
25#include <errno.h>
26#ifndef errno
27extern int errno;
28#endif
29
30#define WAITPID_CHILDREN 8
31static pid_t waited_pid[WAITPID_CHILDREN];
32static int waited_status[WAITPID_CHILDREN];
33
34pid_t
35waitpid (pid_t pid, int *stat_loc, int options)
36{
37  int i;
38  pid_t p;
39
40  if (!options && (pid == -1 || 0 < pid))
41    {
42      /* If we have already waited for this child, return it immediately.  */
43      for (i = 0;  i < WAITPID_CHILDREN;  i++)
44	{
45	  p = waited_pid[i];
46	  if (p && (p == pid || pid == -1))
47	    {
48	      waited_pid[i] = 0;
49	      goto success;
50	    }
51	}
52
53      /* The child has not returned yet; wait for it, accumulating status.  */
54      for (i = 0;  i < WAITPID_CHILDREN;  i++)
55	if (! waited_pid[i])
56	  {
57	    p = wait (&waited_status[i]);
58	    if (p < 0)
59	      return p;
60	    if (p == pid || pid == -1)
61	      goto success;
62	    waited_pid[i] = p;
63	  }
64    }
65
66  /* We cannot emulate this wait call, e.g. because of too many children.  */
67  errno = EINVAL;
68  return -1;
69
70success:
71  if (stat_loc)
72    *stat_loc = waited_status[i];
73  return p;
74}
75