Home | History | Annotate | Line # | Download | only in gen
posix_spawnp.c revision 1.4 
      1 /*	$NetBSD: posix_spawnp.c,v 1.4 2020/05/11 14:54:34 kre Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2011 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Martin Husemann <martin (at) NetBSD.org>.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 __RCSID("$NetBSD: posix_spawnp.c,v 1.4 2020/05/11 14:54:34 kre Exp $");
     35 #endif /* LIBC_SCCS and not lint */
     36 
     37 #include "namespace.h"
     38 
     39 #include <assert.h>
     40 #include <errno.h>
     41 #include <paths.h>
     42 #include <spawn.h>
     43 #include <stdio.h>
     44 #include <stdlib.h>
     45 #include <string.h>
     46 #include <unistd.h>
     47 
     48 
     49 int posix_spawnp(pid_t * __restrict pid, const char * __restrict file,
     50     const posix_spawn_file_actions_t *fa,
     51     const posix_spawnattr_t * __restrict sa,
     52     char * const *__restrict cav, char * const *__restrict env)
     53 {
     54 	char fpath[FILENAME_MAX];
     55 	const char *path, *p;
     56 	size_t lp, ln;
     57 	int err;
     58 
     59 	_DIAGASSERT(file != NULL);
     60 
     61 	/*
     62 	 * If there is a / in the name, fall straight through to posix_spawn().
     63 	 */
     64 	if (strchr(file, '/') != NULL)
     65 		return posix_spawn(pid, file, fa, sa, cav, env);
     66 
     67 	/* Get the path we're searching. */
     68 	if ((path = getenv("PATH")) == NULL)
     69 		path = _PATH_DEFPATH;
     70 
     71 	/*
     72 	 * Find an executable image with the given name in the PATH
     73 	 */
     74 
     75 	ln = strlen(file);
     76 	err = 0;
     77 	do {
     78 		/* Find the end of this path element. */
     79 		for (p = path; *path != 0 && *path != ':'; path++)
     80 			continue;
     81 		/*
     82 		 * It's a SHELL path -- double, leading and trailing colons
     83 		 * mean the current directory.
     84 		 */
     85 		if (p == path) {
     86 			p = ".";
     87 			lp = 1;
     88 		} else
     89 			lp = (size_t)(path - p);
     90 
     91 		/*
     92 		 * Once we gain chdir/fchdir file actions, this will need
     93 		 * serious work, as we must treat "." relative to the
     94 		 * target of the (final) chdir performed.
     95 		 *
     96 		 * Fortunately, that day is yet to come.
     97 		 */
     98 
     99 		/*
    100 		 * If the path is too long complain.  This is a possible
    101 		 * security issue; given a way to make the path too long
    102 		 * the user may execute the wrong program.
    103 		 */
    104 		if (lp + ln + 2 > sizeof(fpath)) {
    105 			(void)write(STDERR_FILENO, "posix_spawnp: ", 14);
    106 			(void)write(STDERR_FILENO, p, lp);
    107 			(void)write(STDERR_FILENO, ": path too long\n", 16);
    108 			continue;
    109 		}
    110 		memcpy(fpath, p, lp);
    111 		fpath[lp] = '/';
    112 		memcpy(fpath + lp + 1, file, ln);
    113 		fpath[lp + ln + 1] = '\0';
    114 
    115 		/*
    116 		 * It would be nice (much better) to try posix_spawn()
    117 		 * here, using the current fpath as the filename, but
    118 		 * there's no guarantee that it is safe to execute it
    119 		 * twice (the file actions may screw us) so that we
    120 		 * cannot do.   This test is weak, barely even adequate.
    121 		 * but unless we are forced into making posix_spawmp()
    122 		 * become a system call (with PATH as an arg, or an array
    123 		 * of possible paths to try, based upon PATH and file)
    124 		 * we really have no better method.
    125 		 */
    126 		if (access(fpath, X_OK) == 0)
    127 			break;
    128 
    129 		if (err == 0)
    130 			err = errno;
    131 
    132 		fpath[0] = '\0';
    133 
    134 
    135 	} while (*path++ == ':');	/* Otherwise, *path was NUL */
    136 
    137 	if (fpath[0] == '\0')
    138 		return err;
    139 
    140 	/*
    141 	 * Use posix_spawn() with the found binary
    142 	 */
    143 	return posix_spawn(pid, fpath, fa, sa, cav, env);
    144 }
    145