/***********************************************************************

*                                                                      *

*               This software is part of the ast package               *

*          Copyright (c) 1985-2012 AT&T Intellectual Property          *

*                      and is licensed under the                       *

*                 Eclipse Public License, Version 1.0                  *

*                    by AT&T Intellectual Property                     *

*                                                                      *

*                A copy of the License is available at                 *

*          http://www.eclipse.org/org/documents/epl-v10.html           *

*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *

*                                                                      *

*              Information and Software Systems Research               *

*                            AT&T Research                             *

*                           Florham Park NJ                            *

*                                                                      *

*                 Glenn Fowler <gsf@research.att.com>                  *

*                  David Korn <dgk@research.att.com>                   *

*                   Phong Vo <kpv@research.att.com>                    *

*                                                                      *

***********************************************************************/

#pragma prototyped

/*

 * spawnveg -- spawnve with process group or session control

 *

 *	pgid	<0	setsid()	[session group leader]

 *		 0	nothing		[retain session and process group]

 *		 1	setpgid(0,0)	[process group leader]

 *		>1	setpgid(0,pgid)	[join process group]

 */

#include <ast.h>

#if _lib_spawnveg

NoN(spawnveg)

#else

#if _lib_posix_spawn > 1	/* reports underlying exec() errors */

#include <spawn.h>

#include <error.h>

#include <wait.h>

pid_t

spawnveg(const char* path, char* const argv[], char* const envv[], pid_t pgid)

{

	int			err;

	pid_t			pid;

	posix_spawnattr_t	attr;

	if (err = posix_spawnattr_init(&attr))

		goto nope;

	if (pgid)

	{

		if (pgid <= 1)

			pgid = 0;

		if (err = posix_spawnattr_setpgroup(&attr, pgid))

			goto bad;

		if (err = posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETPGROUP))

			goto bad;

	}

	if (err = posix_spawn(&pid, path, NiL, &attr, argv, envv ? envv : environ))

		goto bad;

	posix_spawnattr_destroy(&attr);

#if _lib_posix_spawn < 2

	if (waitpid(pid, &err, WNOHANG|WNOWAIT) == pid && EXIT_STATUS(err) == 127)

	{

		while (waitpid(pid, NiL, 0) == -1 && errno == EINTR);

		if (!access(path, X_OK))

			errno = ENOEXEC;

		pid = -1;

	}

#endif

	return pid;

 bad:

	posix_spawnattr_destroy(&attr);

 nope:

	errno = err;

	return -1;

}

#else

#if _lib_spawn_mode

#include <process.h>

#ifndef P_NOWAIT

#define P_NOWAIT	_P_NOWAIT

#endif

#ifndef P_DETACH

#define P_DETACH	_P_DETACH

#endif

pid_t

spawnveg(const char* path, char* const argv[], char* const envv[], pid_t pgid)

{

	return spawnve(pgid ? P_DETACH : P_NOWAIT, path, argv, envv ? envv : environ);

}

#else

#if _lib_spawn && _hdr_spawn && _mem_pgroup_inheritance

#include <spawn.h>

/*

 * open-edition/mvs/zos fork+exec+(setpgid)

 */

pid_t

spawnveg(const char* path, char* const argv[], char* const envv[], pid_t pgid)

{

	struct inheritance	inherit;

	inherit.flags = 0;

	if (pgid)

	{

		inherit.flags |= SPAWN_SETGROUP;

		inherit.pgroup = (pgid > 1) ? pgid : SPAWN_NEWPGROUP;

	}

	return spawn(path, 0, (int*)0, &inherit, (const char**)argv, (const char**)envv);

}

#else

#include <error.h>

#include <wait.h>

#include <sig.h>

#include <ast_tty.h>

#include <ast_vfork.h>

#ifndef ENOSYS

#define ENOSYS	EINVAL

#endif

#if _lib_spawnve && _hdr_process

#include <process.h>

#if defined(P_NOWAIT) || defined(_P_NOWAIT)

#undef	_lib_spawnve

#endif

#endif

#if !_lib_vfork

#undef	_real_vfork

#endif

/*

 * fork+exec+(setsid|setpgid)

 */

pid_t

spawnveg(const char* path, char* const argv[], char* const envv[], pid_t pgid)

{

#if _lib_fork || _lib_vfork

	int			n;

	int			m;

	pid_t			pid;

	pid_t			rid;

#if _real_vfork

	volatile int		exec_errno;

	volatile int* volatile	exec_errno_ptr;

#else

	int			err[2];

#endif

#endif

#if 0

	if (access(path, X_OK))

		return -1;

#endif

	if (!envv)

		envv = environ;

#if _lib_spawnve

#if _lib_fork || _lib_vfork

	if (!pgid)

#endif

		return spawnve(path, argv, envv);

#endif

#if _lib_fork || _lib_vfork

	n = errno;

#if _real_vfork

	exec_errno = 0;

	exec_errno_ptr = &exec_errno;

#else

	if (pipe(err) < 0)

		err[0] = -1;

	else

	{

		fcntl(err[0], F_SETFD, FD_CLOEXEC);

		fcntl(err[1], F_SETFD, FD_CLOEXEC);

	}

#endif

	sigcritical(SIG_REG_EXEC|SIG_REG_PROC);

#if _lib_vfork

	pid = vfork();

#else

	pid = fork();

#endif

	if (pid == -1)

		n = errno;

	else if (!pid)

	{

		sigcritical(0);

		if (pgid == -1)

			setsid();

		else if (pgid)

		{

			m = 0;

			if (pgid == 1 || pgid == -2 && (m = 1))

				pgid = getpid();

			if (setpgid(0, pgid) < 0 && errno == EPERM)

				setpgid(pgid, 0);

#if _lib_tcgetpgrp

			if (m)

				tcsetpgrp(2, pgid);

#else

#ifdef TIOCSPGRP

			if (m)

				ioctl(2, TIOCSPGRP, &pgid);

#endif

#endif

		}

		execve(path, argv, envv);

#if _real_vfork

		*exec_errno_ptr = errno;

#else

		if (err[0] != -1)

		{

			m = errno;

			write(err[1], &m, sizeof(m));

		}

#endif

		_exit(errno == ENOENT ? EXIT_NOTFOUND : EXIT_NOEXEC);

	}

	rid = pid;

#if _real_vfork

	if (pid != -1 && (m = *exec_errno_ptr))

	{

		while (waitpid(pid, NiL, 0) == -1 && errno == EINTR);

		rid = pid = -1;

		n = m;

	}

#else

	if (err[0] != -1)

	{

		close(err[1]);

		if (pid != -1)

		{

			m = 0;

			while (read(err[0], &m, sizeof(m)) == -1)

				if (errno != EINTR)

				{

					m = errno;

					break;

				}

			if (m)

			{

				while (waitpid(pid, &n, 0) && errno == EINTR);

				rid = pid = -1;

				n = m;

			}

		}

		close(err[0]);

	}

#endif

	sigcritical(0);

	if (pid != -1 && pgid > 0)

	{

		/*

		 * parent and child are in a race here

		 */

		if (pgid == 1)

			pgid = pid;

		if (setpgid(pid, pgid) < 0 && pid != pgid && errno == EPERM)

			setpgid(pid, pid);

	}

	errno = n;

	return rid;

#else

	errno = ENOSYS;

	return -1;

#endif

}

#endif

#endif

#endif

#endif