Prex Home / Browse Source - Prex Version: 0.9.0

root/usr/lib/libc/gen/execvp.c

DEFINITIONS

1. execvp

   1 /*-
   2  * Copyright (c) 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  30 #include <sys/cdefs.h>
  31 #include <assert.h>
  32 #include <errno.h>
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include <limits.h>
  37 #include <paths.h>
  38 #include <unistd.h>
  40 extern char **environ;
  42 int
execvp(const char *name, char * const *argv)
  44 {
  45         const char **memp;
  46         int cnt;
size_t lp, ln = 0;
  48         int eacces = 0;
  49         unsigned int etxtbsy = 0;
  50         char buf[PATH_MAX];
  51         const char *bp, *path, *p;
  53         /* "" is not a valid filename; check this before traversing PATH. */
  54         if (name[0] == '\0') {
errno = ENOENT;
  56                 goto done;
  57         }
  58         /* If it's an absolute or relative path name, it's easy. */
  59         if (strchr(name, '/')) {
bp = name;
path = "";
  62                 goto retry;
  63         }
bp = buf;
  66         /* Get the path we're searching. */
  67         if (!(path = getenv("PATH")))
path = _PATH_DEFPATH;
ln = strlen(name);
  71         do {
  72                 /* Find the end of this path element. */
  73                 for (p = path; *path != 0 && *path != ':'; path++)
  74                         continue;
  75                 /*
  76                  * It's a SHELL path -- double, leading and trailing colons
  77                  * mean the current directory.
  78                  */
  79                 if (p == path) {
p = ".";
lp = 1;
  82                 } else
lp = path - p;
  85                 /*
  86                  * If the path is too long complain.  This is a possible
  87                  * security issue; given a way to make the path too long
  88                  * the user may execute the wrong program.
  89                  */
  90                 if (lp + ln + 2 > sizeof(buf))
  91                         continue;
memcpy(buf, p, lp);
buf[lp] = '/';
memcpy(buf + lp + 1, name, ln);
buf[lp + ln + 1] = '\0';
retry:          (void)execve(bp, argv, environ);
  98                 switch (errno) {
  99                 case EACCES:
eacces = 1;
 101                         break;
 102                 case ENOTDIR:
 103                 case ENOENT:
 104                         break;
 105                 case ENOEXEC:
 106                         for (cnt = 0; argv[cnt] != NULL; ++cnt)
 107                                 continue;
 108                         if ((memp = (const char **)(alloca((cnt + 2) * sizeof(*memp)))) == NULL)
 109                                 goto done;
memp[0] = _PATH_BSHELL;
memp[1] = bp;
 112                         (void)memcpy(&memp[2], &argv[1], cnt * sizeof(*memp));
 113                         (void)execve(_PATH_BSHELL, (char * const *)memp,
environ);
 115                         goto done;
 116                 case ETXTBSY:
 117                         if (etxtbsy < 3)
 118                                 (void)sleep(++etxtbsy);
 119                         goto retry;
 120                 default:
 121                         goto done;
 122                 }
 123         } while (*path++ == ':');       /* Otherwise, *path was NUL */
 124         if (eacces)
errno = EACCES;
 126         else if (!errno)
errno = ENOENT;
done:
 129         return (-1);
 130 }