lib/libc/gen/execvp.c

   1 /*      $NetBSD: execvp.c,v 1.29 2006/11/09 03:57:26 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 1.29 2006/11/09 03:57:26 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 #endif
  55
  56 extern char **environ;
  57
  58 int
  59 execvp(const char *name, char * const *argv)
  60 {
  61         const char **memp;
  62         int cnt;
  63         size_t lp, ln;
  64         int eacces = 0;
  65         unsigned int etxtbsy = 0;
  66         char buf[PATH_MAX];
  67         const char *bp, *path, *p;
  68
  69         _DIAGASSERT(name != NULL);
  70
  71         /* "" is not a valid filename; check this before traversing PATH. */
  72         if (name[0] == '\0') {
  73                 errno = ENOENT;
  74                 goto done;
  75         }
  76         ln = strlen(name);
  77         /* If it's an absolute or relative path name, it's easy. */
  78         if (strchr(name, '/')) {
  79                 bp = name;
  80                 path = "";
  81                 goto retry;
  82         }
  83         bp = buf;
  84
  85         /* Get the path we're searching. */
  86         if (!(path = getenv("PATH")))
  87                 path = _PATH_DEFPATH;
  88
  89         do {
  90                 /* Find the end of this path element. */
  91                 for (p = path; *path != 0 && *path != ':'; path++)
  92                         continue;
  93                 /*
  94                  * It's a SHELL path -- double, leading and trailing colons
  95                  * mean the current directory.
  96                  */
  97                 if (p == path) {
  98                         p = ".";
  99                         lp = 1;
 100                 } else
 101                         lp = path - p;
 102
 103                 /*
 104                  * If the path is too long complain.  This is a possible
 105                  * security issue; given a way to make the path too long
 106                  * the user may execute the wrong program.
 107                  */
 108                 if (lp + ln + 2 > sizeof(buf)) {
 109                         (void)write(STDERR_FILENO, "execvp: ", 8);
 110                         (void)write(STDERR_FILENO, p, lp);
 111                         (void)write(STDERR_FILENO, ": path too long\n", 16);
 112                         continue;
 113                 }
 114                 memcpy(buf, p, lp);
 115                 buf[lp] = '/';
 116                 memcpy(buf + lp + 1, name, ln);
 117                 buf[lp + ln + 1] = '\0';
 118
 119 retry:          (void)execve(bp, argv, environ);
 120                 switch (errno) {
 121                 case EACCES:
 122                         eacces = 1;
 123                         break;
 124                 case ENOTDIR:
 125                 case ENOENT:
 126                         break;
 127                 case ENOEXEC:
 128                         for (cnt = 0; argv[cnt] != NULL; ++cnt)
 129                                 continue;
 130                         /*
 131                          * we can't use malloc here because, if we are doing
 132                          * vfork+exec, it leaks memory in the parent.
 133                          */
 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, __UNCONST(memp), environ);
 140                         goto done;
 141                 case ETXTBSY:
 142                         if (etxtbsy < 3)
 143                                 (void)sleep(++etxtbsy);
 144                         goto retry;
 145                 default:
 146                         goto done;
 147                 }
 148         } while (*path++ == ':');       /* Otherwise, *path was NUL */
 149         if (eacces)
 150                 errno = EACCES;
 151         else if (!errno)
 152                 errno = ENOENT;
 153 done:
 154         return (-1);
 155 }