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execvp.c revision 1.13 
      1 /*	$NetBSD: execvp.c,v 1.13 1999/09/16 11:36:19 lukem 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 1.13 1999/09/16 11:36:19 lukem Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include "namespace.h"
     46 #include <errno.h>
     47 #include <stdio.h>
     48 #include <stdlib.h>
     49 #include <string.h>
     50 #include <limits.h>
     51 #include <unistd.h>
     52 #include <paths.h>
     53 #include "reentrant.h"
     54 
     55 #ifdef __weak_alias
     56 __weak_alias(execvp,_execvp);
     57 #endif
     58 
     59 extern char **environ;
     60 #ifdef _REENT
     61 extern rwlock_t __environ_lock;
     62 #endif
     63 
     64 int
     65 execvp(name, argv)
     66 	const char *name;
     67 	char * const *argv;
     68 {
     69 	const char **memp;
     70 	int cnt;
     71 	size_t lp, ln;
     72 	char *p;
     73 	int eacces = 0;
     74 	unsigned int etxtbsy = 0;
     75 	char *cur, *path, buf[PATH_MAX];
     76 	const char *bp;
     77 
     78 	/* "" is not a valid filename; check this before traversing PATH. */
     79 	if (name[0] == '\0') {
     80 		errno = ENOENT;
     81 		path = NULL;
     82 		goto done;
     83 	}
     84 	/* If it's an absolute or relative path name, it's easy. */
     85 	if (strchr(name, '/')) {
     86 		bp = name;
     87 		cur = path = NULL;
     88 		goto retry;
     89 	}
     90 	bp = buf;
     91 
     92 	/* Get the path we're searching. */
     93 	if (!(path = getenv("PATH")))
     94 		path = _PATH_DEFPATH;
     95 	cur = path = strdup(path);
     96 
     97 	while ((p = strsep(&cur, ":")) != NULL) {
     98 		/*
     99 		 * It's a SHELL path -- double, leading and trailing colons
    100 		 * mean the current directory.
    101 		 */
    102 		if (!*p) {
    103 			p = ".";
    104 			lp = 1;
    105 		} else
    106 			lp = strlen(p);
    107 		ln = strlen(name);
    108 
    109 		/*
    110 		 * If the path is too long complain.  This is a possible
    111 		 * security issue; given a way to make the path too long
    112 		 * the user may execute the wrong program.
    113 		 */
    114 		if (lp + ln + 2 > sizeof(buf)) {
    115 			(void)write(STDERR_FILENO, "execvp: ", 8);
    116 			(void)write(STDERR_FILENO, p, lp);
    117 			(void)write(STDERR_FILENO, ": path too long\n", 16);
    118 			continue;
    119 		}
    120 		memmove(buf, p, lp);
    121 		buf[lp] = '/';
    122 		memmove(buf + lp + 1, name, ln);
    123 		buf[lp + ln + 1] = '\0';
    124 
    125 retry:		rwlock_rdlock(&__environ_lock);
    126 		(void)execve(bp, argv, environ);
    127 		rwlock_unlock(&__environ_lock);
    128 		switch (errno) {
    129 		case EACCES:
    130 			eacces = 1;
    131 			break;
    132 		case ENOENT:
    133 			break;
    134 		case ENOEXEC:
    135 			for (cnt = 0; argv[cnt] != NULL; ++cnt);
    136 			if ((memp = malloc((cnt + 2) * sizeof (*memp))) == NULL)
    137 				goto done;
    138 			memp[0] = _PATH_BSHELL;
    139 			memp[1] = bp;
    140 			(void)memmove(&memp[2], &argv[1], cnt * sizeof (*memp));
    141 			rwlock_rdlock(&__environ_lock);
    142 			(void)execve(_PATH_BSHELL, (char * const *)memp, environ);
    143 			rwlock_unlock(&__environ_lock);
    144 			free(memp);
    145 			goto done;
    146 		case ETXTBSY:
    147 			if (etxtbsy < 3)
    148 				(void)sleep(++etxtbsy);
    149 			goto retry;
    150 		default:
    151 			goto done;
    152 		}
    153 	}
    154 	if (eacces)
    155 		errno = EACCES;
    156 	else if (!errno)
    157 		errno = ENOENT;
    158 done:	if (path)
    159 		free(path);
    160 	return (-1);
    161 }
    162