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execvp.c revision 1.28 
      1 /*	$NetBSD: execvp.c,v 1.28 2006/11/09 02:51:52 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1991, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)exec.c	8.1 (Berkeley) 6/4/93";
     36 #else
     37 __RCSID("$NetBSD: execvp.c,v 1.28 2006/11/09 02:51:52 christos Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include <assert.h>
     43 #include <errno.h>
     44 #include <stdio.h>
     45 #include <stdlib.h>
     46 #include <string.h>
     47 #include <limits.h>
     48 #include <unistd.h>
     49 #include <paths.h>
     50 #if defined(__SSP__) || defined(__SSP_ALL__)
     51 #include <sys/mman.h>
     52 #endif
     53 #include "reentrant.h"
     54 
     55 #ifdef __weak_alias
     56 __weak_alias(execvp,_execvp)
     57 #endif
     58 
     59 extern char **environ;
     60 
     61 int
     62 execvp(const char *name, char * const *argv)
     63 {
     64 	const char **memp;
     65 	int cnt;
     66 	size_t lp, ln;
     67 	int eacces = 0;
     68 	unsigned int etxtbsy = 0;
     69 	char buf[PATH_MAX];
     70 	const char *bp, *path, *p;
     71 
     72 	_DIAGASSERT(name != NULL);
     73 
     74 	/* "" is not a valid filename; check this before traversing PATH. */
     75 	if (name[0] == '\0') {
     76 		errno = ENOENT;
     77 		goto done;
     78 	}
     79 	ln = strlen(name);
     80 	/* If it's an absolute or relative path name, it's easy. */
     81 	if (strchr(name, '/')) {
     82 		bp = name;
     83 		path = "";
     84 		goto retry;
     85 	}
     86 	bp = buf;
     87 
     88 	/* Get the path we're searching. */
     89 	if (!(path = getenv("PATH")))
     90 		path = _PATH_DEFPATH;
     91 
     92 	do {
     93 		/* Find the end of this path element. */
     94 		for (p = path; *path != 0 && *path != ':'; path++)
     95 			continue;
     96 		/*
     97 		 * It's a SHELL path -- double, leading and trailing colons
     98 		 * mean the current directory.
     99 		 */
    100 		if (p == path) {
    101 			p = ".";
    102 			lp = 1;
    103 		} else
    104 			lp = path - p;
    105 
    106 		/*
    107 		 * If the path is too long complain.  This is a possible
    108 		 * security issue; given a way to make the path too long
    109 		 * the user may execute the wrong program.
    110 		 */
    111 		if (lp + ln + 2 > sizeof(buf)) {
    112 			(void)write(STDERR_FILENO, "execvp: ", 8);
    113 			(void)write(STDERR_FILENO, p, lp);
    114 			(void)write(STDERR_FILENO, ": path too long\n", 16);
    115 			continue;
    116 		}
    117 		memcpy(buf, p, lp);
    118 		buf[lp] = '/';
    119 		memcpy(buf + lp + 1, name, ln);
    120 		buf[lp + ln + 1] = '\0';
    121 
    122 retry:		(void)execve(bp, argv, environ);
    123 		switch (errno) {
    124 		case EACCES:
    125 			eacces = 1;
    126 			break;
    127 		case ENOTDIR:
    128 		case ENOENT:
    129 			break;
    130 		case ENOEXEC:
    131 			for (cnt = 0; argv[cnt] != NULL; ++cnt)
    132 				continue;
    133 			ln = (cnt + 2) * sizeof(*memp);
    134 #if defined(__SSP__) || defined(__SSP_ALL__)
    135 			if ((memp = mmap(NULL, ln, PROT_READ|PROT_WRITE,
    136 			    MAP_ANON, -1, 0)) == MAP_FAILED)
    137 				goto done;
    138 #else
    139 			if ((memp = alloca(ln)) == NULL)
    140 				goto done;
    141 #endif
    142 			memp[0] = _PATH_BSHELL;
    143 			memp[1] = bp;
    144 			(void)memcpy(&memp[2], &argv[1], cnt * sizeof(*memp));
    145 			(void)execve(_PATH_BSHELL, __UNCONST(memp), environ);
    146 #if defined(__SSP__) || defined(__SSP_ALL__)
    147 			eacces = errno;
    148 			(void)munmap(memp, ln);
    149 			errno = eacces;
    150 #endif
    151 			goto done;
    152 		case ETXTBSY:
    153 			if (etxtbsy < 3)
    154 				(void)sleep(++etxtbsy);
    155 			goto retry;
    156 		default:
    157 			goto done;
    158 		}
    159 	} while (*path++ == ':');	/* Otherwise, *path was NUL */
    160 	if (eacces)
    161 		errno = EACCES;
    162 	else if (!errno)
    163 		errno = ENOENT;
    164 done:
    165 	return (-1);
    166 }
    167