/* Utilities to execute a program in a subprocess (possibly linked by pipes
   with other subprocesses), and wait for it.  DJGPP specialization.
   Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2003
   Free Software Foundation, Inc.

This file is part of the libiberty library.
Libiberty is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.

Libiberty is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with libiberty; see the file COPYING.LIB.  If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include "pex-common.h"

#include <stdio.h>
#include <errno.h>
#ifdef NEED_DECLARATION_ERRNO
extern int errno;
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#include <process.h>

/* Use ECHILD if available, otherwise use EINVAL.  */
#ifdef ECHILD
#define PWAIT_ERROR ECHILD
#else
#define PWAIT_ERROR EINVAL
#endif

/* MSDOS doesn't multitask, but for the sake of a consistent interface
   the code behaves like it does.  pexecute runs the program, tucks the
   exit code away, and returns a "pid".  pwait must be called to fetch the
   exit code.  */

/* For communicating information from pexecute to pwait.  */
static int last_pid = 0;
static int last_status = 0;
static int last_reaped = 0;

int
pexecute (const char *program, char * const *argv, const char *this_pname,
          const char *temp_base, char **errmsg_fmt,
          char **errmsg_arg, int flags)
{
  int rc;

  last_pid++;
  if (last_pid < 0)
    last_pid = 1;

  if ((flags & PEXECUTE_ONE) != PEXECUTE_ONE)
    abort ();

  /* ??? What are the possible return values from spawnv?  */
  rc = (flags & PEXECUTE_SEARCH ? spawnvp : spawnv) (P_WAIT, program, argv);

  if (rc == -1)
    {
      *errmsg_fmt = install_error_msg;
      *errmsg_arg = (char *)program;
      return -1;
    }

  /* Tuck the status away for pwait, and return a "pid".  */
  last_status = rc << 8;
  return last_pid;
}

int
pwait (int pid, int *status, int flags)
{
  /* On MSDOS each pexecute must be followed by its associated pwait.  */
  if (pid != last_pid
      /* Called twice for the same child?  */
      || pid == last_reaped)
    {
      errno = PWAIT_ERROR;
      return -1;
    }
  /* ??? Here's an opportunity to canonicalize the values in STATUS.
     Needed?  */
  *status = (last_status >> 8);
  last_reaped = last_pid;
  return last_pid;
}