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execvp.c revision 1.31 
      1 /*	$NetBSD: execvp.c,v 1.31 2014/09/26 19:28:03 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 1.31 2014/09/26 19:28:03 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 #include "reentrant.h"
     51 
     52 #ifdef __weak_alias
     53 __weak_alias(execvp,_execvp)
     54 __weak_alias(execvpe,_execvpe)
     55 #endif
     56 
     57 int
     58 execvpe(const char *name, char * const *argv, char * const * envp)
     59 {
     60 	const char **memp;
     61 	int cnt;
     62 	size_t lp, ln;
     63 	int eacces = 0;
     64 	unsigned int etxtbsy = 0;
     65 	char buf[PATH_MAX];
     66 	const char *bp, *path, *p;
     67 
     68 	_DIAGASSERT(name != NULL);
     69 
     70 	/* "" is not a valid filename; check this before traversing PATH. */
     71 	if (name[0] == '\0') {
     72 		errno = ENOENT;
     73 		goto done;
     74 	}
     75 	ln = strlen(name);
     76 	/* If it's an absolute or relative path name, it's easy. */
     77 	if (strchr(name, '/')) {
     78 		bp = name;
     79 		path = "";
     80 		goto retry;
     81 	}
     82 	bp = buf;
     83 
     84 	/* Get the path we're searching. */
     85 	if (!(path = getenv("PATH")))
     86 		path = _PATH_DEFPATH;
     87 
     88 	do {
     89 		/* Find the end of this path element. */
     90 		for (p = path; *path != 0 && *path != ':'; path++)
     91 			continue;
     92 		/*
     93 		 * It's a SHELL path -- double, leading and trailing colons
     94 		 * mean the current directory.
     95 		 */
     96 		if (p == path) {
     97 			p = ".";
     98 			lp = 1;
     99 		} else
    100 			lp = path - p;
    101 
    102 		/*
    103 		 * If the path is too long complain.  This is a possible
    104 		 * security issue; given a way to make the path too long
    105 		 * the user may execute the wrong program.
    106 		 */
    107 		if (lp + ln + 2 > sizeof(buf)) {
    108 			(void)write(STDERR_FILENO, "execvp: ", 8);
    109 			(void)write(STDERR_FILENO, p, lp);
    110 			(void)write(STDERR_FILENO, ": path too long\n", 16);
    111 			continue;
    112 		}
    113 		memcpy(buf, p, lp);
    114 		buf[lp] = '/';
    115 		memcpy(buf + lp + 1, name, ln);
    116 		buf[lp + ln + 1] = '\0';
    117 
    118 retry:		(void)execve(bp, argv, envp);
    119 		switch (errno) {
    120 		case EACCES:
    121 			eacces = 1;
    122 			break;
    123 		case ENOTDIR:
    124 		case ENOENT:
    125 			break;
    126 		case ENOEXEC:
    127 			for (cnt = 0; argv[cnt] != NULL; ++cnt)
    128 				continue;
    129 			/*
    130 			 * we can't use malloc here because, if we are doing
    131 			 * vfork+exec, it leaks memory in the parent.
    132 			 */
    133 			if ((memp = alloca((cnt + 2) * sizeof(*memp))) == NULL)
    134 				goto done;
    135 			memp[0] = _PATH_BSHELL;
    136 			memp[1] = bp;
    137 			(void)memcpy(&memp[2], &argv[1], cnt * sizeof(*memp));
    138 			(void)execve(_PATH_BSHELL, __UNCONST(memp), envp);
    139 			goto done;
    140 		case ETXTBSY:
    141 			if (etxtbsy < 3)
    142 				(void)sleep(++etxtbsy);
    143 			goto retry;
    144 		default:
    145 			goto done;
    146 		}
    147 	} while (*path++ == ':');	/* Otherwise, *path was NUL */
    148 	if (eacces)
    149 		errno = EACCES;
    150 	else if (!errno)
    151 		errno = ENOENT;
    152 done:
    153 	return (-1);
    154 }
    155 
    156 extern char **environ;
    157 
    158 int
    159 execvp(const char *name, char * const *argv)
    160 {
    161 	return execvpe(name, argv, environ);
    162 }
    163