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execvp.c revision 1.23 
      1 /*	$NetBSD: execvp.c,v 1.23 2003/03/15 04:41:17 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. 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 1.23 2003/03/15 04:41:17 christos 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 
     62 int
     63 execvp(const char *name, char * const *argv)
     64 {
     65 	const char **memp;
     66 	int cnt;
     67 	size_t lp, ln;
     68 	int eacces = 0;
     69 	unsigned int etxtbsy = 0;
     70 	char buf[PATH_MAX];
     71 	const char *bp, *path, *p;
     72 
     73 	_DIAGASSERT(name != NULL);
     74 
     75 	/* "" is not a valid filename; check this before traversing PATH. */
     76 	if (name[0] == '\0') {
     77 		errno = ENOENT;
     78 		goto done;
     79 	}
     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 	ln = strlen(name);
     93 	do {
     94 		/* Find the end of this path element. */
     95 		for (p = path; *path != 0 && *path != ':'; path++)
     96 			continue;
     97 		/*
     98 		 * It's a SHELL path -- double, leading and trailing colons
     99 		 * mean the current directory.
    100 		 */
    101 		if (p == path) {
    102 			p = ".";
    103 			lp = 1;
    104 		} else
    105 			lp = path - p;
    106 
    107 		/*
    108 		 * If the path is too long complain.  This is a possible
    109 		 * security issue; given a way to make the path too long
    110 		 * the user may execute the wrong program.
    111 		 */
    112 		if (lp + ln + 2 > sizeof(buf)) {
    113 			(void)write(STDERR_FILENO, "execvp: ", 8);
    114 			(void)write(STDERR_FILENO, p, lp);
    115 			(void)write(STDERR_FILENO, ": path too long\n", 16);
    116 			continue;
    117 		}
    118 		memcpy(buf, p, lp);
    119 		buf[lp] = '/';
    120 		memcpy(buf + lp + 1, name, ln);
    121 		buf[lp + ln + 1] = '\0';
    122 
    123 retry:		(void)execve(bp, argv, environ);
    124 		switch (errno) {
    125 		case EACCES:
    126 			eacces = 1;
    127 			break;
    128 		case ENOTDIR:
    129 		case ENOENT:
    130 			break;
    131 		case ENOEXEC:
    132 			for (cnt = 0; argv[cnt] != NULL; ++cnt)
    133 				continue;
    134 			if ((memp = alloca((cnt + 2) * sizeof(*memp))) == NULL)
    135 				goto done;
    136 			memp[0] = _PATH_BSHELL;
    137 			memp[1] = bp;
    138 			(void)memcpy(&memp[2], &argv[1], cnt * sizeof(*memp));
    139 			(void)execve(_PATH_BSHELL, (char * const *)memp,
    140 			    environ);
    141 			goto done;
    142 		case ETXTBSY:
    143 			if (etxtbsy < 3)
    144 				(void)sleep(++etxtbsy);
    145 			goto retry;
    146 		default:
    147 			goto done;
    148 		}
    149 	} while (*path++ == ':');	/* Otherwise, *path was NUL */
    150 	if (eacces)
    151 		errno = EACCES;
    152 	else if (!errno)
    153 		errno = ENOENT;
    154 done:
    155 	return (-1);
    156 }
    157