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	1	/*
	2	* Copyright (c) 2006-2012 Apple Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. Please obtain a copy of the License at
	10	* http://www.opensource.apple.com/apsl/ and read it before using this
	11	* file.
	12	*
	13	* The Original Code and all software distributed under the License are
	14	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	15	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	16	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	17	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	18	* Please see the License for the specific language governing rights and
	19	* limitations under the License.
	20	*
	21	* @APPLE_LICENSE_HEADER_END@
	22	*/
	23
	24	/*
	25	* [SPN] Support for _POSIX_SPAWN
	26	*/
	27
	28	#include <spawn.h>
	29	#include <spawn_private.h>
	30	#include <sys/spawn_internal.h>
	31	#include <stdlib.h>
	32	#include <errno.h>
	33	#include <limits.h> /* for OPEN_MAX, PATH_MAX */
	34	#include <string.h> /* for strlcpy() */
	35	#include <paths.h> /* for _PATH_DEFPATH */
	36	#include <sys/stat.h> /* for struct stat */
	37
	38	/*
	39	* posix_spawnp
	40	*
	41	* Description: Create a new process from the process image corresponding to
	42	* the supplied 'file' argument and the parent processes path
	43	* environment.
	44	*
	45	* Parameters: pid Pointer to pid_t to receive the
	46	* PID of the spawned process, if
	47	* successful and 'pid' != NULL
	48	* file Name of image file to spawn
	49	* file_actions spawn file actions object which
	50	* describes file actions to be
	51	* performed during the spawn
	52	* attrp spawn attributes object which
	53	* describes attributes to be
	54	* applied during the spawn
	55	* argv argument vector array; NULL
	56	* terminated
	57	* envp environment vector array; NULL
	58	* terminated
	59	*
	60	* Returns: 0 Success
	61	* !0 An errno value indicating the
	62	* cause of the failure to spawn
	63	*
	64	* Notes: Much of this function is derived from code from execvP() from
	65	* exec.c in libc; this common code should be factored out at
	66	* some point to prevent code duplication or desynchronization vs.
	67	* bug fixes applied to one set of code but not the other.
	68	*/
	69	int
	70	posix_spawnp(pid_t * __restrict pid, const char * __restrict file,
	71	const posix_spawn_file_actions_t *file_actions,
	72	const posix_spawnattr_t * __restrict attrp,
	73	char const argv[ __restrict], char const envp[ __restrict])
	74	{
	75	const char *env_path;
	76	char *bp;
	77	char *cur;
	78	char *p;
	79	char **memp;
	80	int lp;
	81	int ln;
	82	int cnt;
	83	int err = 0;
	84	int eacces = 0;
	85	struct stat sb;
	86	char path_buf[PATH_MAX];
	87
	88	if ((env_path = getenv("PATH")) == NULL)
	89	env_path = _PATH_DEFPATH;
	90
	91	/* If it's an absolute or relative path name, it's easy. */
	92	if (index(file, '/')) {
	93	bp = (char *)file;
	94	cur = NULL;
	95	goto retry;
	96	}
	97	bp = path_buf;
	98
	99	/* If it's an empty path name, fail in the usual POSIX way. */
	100	if (*file == '\0')
	101	return (ENOENT);
	102
	103	if ((cur = alloca(strlen(env_path) + 1)) == NULL)
	104	return ENOMEM;
	105	strcpy(cur, env_path);
	106	while ((p = strsep(&cur, ":")) != NULL) {
	107	/*
	108	* It's a SHELL path -- double, leading and trailing colons
	109	* mean the current directory.
	110	*/
	111	if (*p == '\0') {
	112	p = ".";
	113	lp = 1;
	114	} else {
	115	lp = strlen(p);
	116	}
	117	ln = strlen(file);
	118
	119	/*
	120	* If the path is too long complain. This is a possible
	121	* security issue; given a way to make the path too long
	122	* the user may spawn the wrong program.
	123	*/
	124	if (lp + ln + 2 > sizeof(path_buf)) {
	125	err = ENAMETOOLONG;
	126	goto done;
	127	}
	128	bcopy(p, path_buf, lp);
	129	path_buf[lp] = '/';
	130	bcopy(file, path_buf + lp + 1, ln);
	131	path_buf[lp + ln + 1] = '\0';
	132
	133	retry: err = posix_spawn(pid, bp, file_actions, attrp, argv, envp);
	134	switch (err) {
	135	case E2BIG:
	136	case ENOMEM:
	137	case ETXTBSY:
	138	goto done;
	139	case ELOOP:
	140	case ENAMETOOLONG:
	141	case ENOENT:
	142	case ENOTDIR:
	143	break;
	144	case ENOEXEC:
	145	for (cnt = 0; argv[cnt]; ++cnt)
	146	;
	147	memp = alloca((cnt + 2) * sizeof(char *));
	148	if (memp == NULL) {
	149	/* errno = ENOMEM; XXX override ENOEXEC? */
	150	goto done;
	151	}
	152	memp[0] = "sh";
	153	memp[1] = bp;
	154	bcopy(argv + 1, memp + 2, cnt * sizeof(char *));
	155	err = posix_spawn(pid, _PATH_BSHELL, file_actions, attrp, memp, envp);
	156	goto done;
	157	default:
	158	/*
	159	* EACCES may be for an inaccessible directory or
	160	* a non-executable file. Call stat() to decide
	161	* which. This also handles ambiguities for EFAULT
	162	* and EIO, and undocumented errors like ESTALE.
	163	* We hope that the race for a stat() is unimportant.
	164	*/
	165	if (stat(bp, &sb) != 0)
	166	break;
	167	if (err == EACCES) {
	168	eacces = 1;
	169	continue;
	170	}
	171	goto done;
	172	}
	173	}
	174	if (eacces)
	175	err = EACCES;
	176	else
	177	err = ENOENT;
	178	done:
	179	return (err);
	180	}