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execvp.c revision 1.17 
      1 /*	$NetBSD: execvp.c,v 1.17 2001/09/18 05:09:37 simonb 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. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)exec.c	8.1 (Berkeley) 6/4/93";
     40 #else
     41 __RCSID("$NetBSD: execvp.c,v 1.17 2001/09/18 05:09:37 simonb Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include "namespace.h"
     46 #include <assert.h>
     47 #include <errno.h>
     48 #include <stdio.h>
     49 #include <stdlib.h>
     50 #include <string.h>
     51 #include <limits.h>
     52 #include <unistd.h>
     53 #include <paths.h>
     54 #include "reentrant.h"
     55 
     56 #ifdef __weak_alias
     57 __weak_alias(execvp,_execvp)
     58 #endif
     59 
     60 extern char **environ;
     61 #ifdef _REENT
     62 extern rwlock_t __environ_lock;
     63 #endif
     64 
     65 int
     66 execvp(name, argv)
     67 	const char *name;
     68 	char * const *argv;
     69 {
     70 	const char **memp;
     71 	int cnt;
     72 	size_t lp, ln;
     73 	char *p;
     74 	int eacces = 0;
     75 	unsigned int etxtbsy = 0;
     76 	char *cur, *path, buf[PATH_MAX];
     77 	const char *bp;
     78 
     79 	_DIAGASSERT(name != NULL);
     80 
     81 	/* "" is not a valid filename; check this before traversing PATH. */
     82 	if (name[0] == '\0') {
     83 		errno = ENOENT;
     84 		path = NULL;
     85 		goto done;
     86 	}
     87 	/* If it's an absolute or relative path name, it's easy. */
     88 	if (strchr(name, '/')) {
     89 		bp = name;
     90 		cur = path = NULL;
     91 		goto retry;
     92 	}
     93 	bp = buf;
     94 
     95 	/* Get the path we're searching. */
     96 	if (!(path = getenv("PATH")))
     97 		path = _PATH_DEFPATH;
     98 	cur = alloca(strlen(path) + 1);
     99 	strcpy(cur, path);
    100 	path = cur;
    101 
    102 	while ((p = strsep(&cur, ":")) != NULL) {
    103 		/*
    104 		 * It's a SHELL path -- double, leading and trailing colons
    105 		 * mean the current directory.
    106 		 */
    107 		if (!*p) {
    108 			p = ".";
    109 			lp = 1;
    110 		} else
    111 			lp = strlen(p);
    112 		ln = strlen(name);
    113 
    114 		/*
    115 		 * If the path is too long complain.  This is a possible
    116 		 * security issue; given a way to make the path too long
    117 		 * the user may execute the wrong program.
    118 		 */
    119 		if (lp + ln + 2 > sizeof(buf)) {
    120 			(void)write(STDERR_FILENO, "execvp: ", 8);
    121 			(void)write(STDERR_FILENO, p, lp);
    122 			(void)write(STDERR_FILENO, ": path too long\n", 16);
    123 			continue;
    124 		}
    125 		memmove(buf, p, lp);
    126 		buf[lp] = '/';
    127 		memmove(buf + lp + 1, name, ln);
    128 		buf[lp + ln + 1] = '\0';
    129 
    130 retry:		rwlock_rdlock(&__environ_lock);
    131 		(void)execve(bp, argv, environ);
    132 		rwlock_unlock(&__environ_lock);
    133 		switch (errno) {
    134 		case EACCES:
    135 			eacces = 1;
    136 			break;
    137 		case ENOENT:
    138 			break;
    139 		case ENOEXEC:
    140 			for (cnt = 0; argv[cnt] != NULL; ++cnt);
    141 			if ((memp = alloca((cnt + 2) * sizeof (*memp))) == NULL)
    142 				goto done;
    143 			memp[0] = _PATH_BSHELL;
    144 			memp[1] = bp;
    145 			(void)memmove(&memp[2], &argv[1], cnt * sizeof (*memp));
    146 			rwlock_rdlock(&__environ_lock);
    147 			(void)execve(_PATH_BSHELL, (char * const *)memp, environ);
    148 			rwlock_unlock(&__environ_lock);
    149 			goto done;
    150 		case ETXTBSY:
    151 			if (etxtbsy < 3)
    152 				(void)sleep(++etxtbsy);
    153 			goto retry;
    154 		default:
    155 			goto done;
    156 		}
    157 	}
    158 	if (eacces)
    159 		errno = EACCES;
    160 	else if (!errno)
    161 		errno = ENOENT;
    162 done:
    163 	return (-1);
    164 }
    165