arch/um/os-Linux/execvp.c

   1 /* Copyright (C) 2006 by Paolo Giarrusso - modified from glibc' execvp.c.
   2    Original copyright notice follows:
   3
   4    Copyright (C) 1991,92,1995-99,2002,2004 Free Software Foundation, Inc.
   5    This file is part of the GNU C Library.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, write to the Free
  19    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20    02111-1307 USA.  */
  21 #include <unistd.h>
  22
  23 #include <stdbool.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <errno.h>
  27 #include <limits.h>
  28
  29 #ifndef TEST
  30 #include "um_malloc.h"
  31 #else
  32 #include <stdio.h>
  33 #define um_kmalloc malloc
  34 #endif
  35 #include "os.h"
  36
  37 /* Execute FILE, searching in the `PATH' environment variable if it contains
  38    no slashes, with arguments ARGV and environment from `environ'.  */
  39 int execvp_noalloc(char *buf, const char *file, char *const argv[])
  40 {
  41         if (*file == '\0') {
  42                 return -ENOENT;
  43         }
  44
  45         if (strchr (file, '/') != NULL) {
  46                 /* Don't search when it contains a slash.  */
  47                 execv(file, argv);
  48         } else {
  49                 int got_eacces;
  50                 size_t len, pathlen;
  51                 char *name, *p;
  52                 char *path = getenv("PATH");
  53                 if (path == NULL)
  54                         path = ":/bin:/usr/bin";
  55
  56                 len = strlen(file) + 1;
  57                 pathlen = strlen(path);
  58                 /* Copy the file name at the top.  */
  59                 name = memcpy(buf + pathlen + 1, file, len);
  60                 /* And add the slash.  */
  61                 *--name = '/';
  62
  63                 got_eacces = 0;
  64                 p = path;
  65                 do {
  66                         char *startp;
  67
  68                         path = p;
  69                         //Let's avoid this GNU extension.
  70                         //p = strchrnul (path, ':');
  71                         p = strchr(path, ':');
  72                         if (!p)
  73                                 p = strchr(path, '\0');
  74
  75                         if (p == path)
  76                                 /* Two adjacent colons, or a colon at the beginning or the end
  77                                    of `PATH' means to search the current directory.  */
  78                                 startp = name + 1;
  79                         else
  80                                 startp = memcpy(name - (p - path), path, p - path);
  81
  82                         /* Try to execute this name.  If it works, execv will not return.  */
  83                         execv(startp, argv);
  84
  85                         /*
  86                         if (errno == ENOEXEC) {
  87                         }
  88                         */
  89
  90                         switch (errno) {
  91                                 case EACCES:
  92                                         /* Record the we got a `Permission denied' error.  If we end
  93                                            up finding no executable we can use, we want to diagnose
  94                                            that we did find one but were denied access.  */
  95                                         got_eacces = 1;
  96                                 case ENOENT:
  97                                 case ESTALE:
  98                                 case ENOTDIR:
  99                                         /* Those errors indicate the file is missing or not executable
 100                                            by us, in which case we want to just try the next path
 101                                            directory.  */
 102                                 case ENODEV:
 103                                 case ETIMEDOUT:
 104                                         /* Some strange filesystems like AFS return even
 105                                            stranger error numbers.  They cannot reasonably mean
 106                                            anything else so ignore those, too.  */
 107                                 case ENOEXEC:
 108                                         /* We won't go searching for the shell
 109                                          * if it is not executable - the Linux
 110                                          * kernel already handles this enough,
 111                                          * for us. */
 112                                         break;
 113
 114                                 default:
 115                                         /* Some other error means we found an executable file, but
 116                                            something went wrong executing it; return the error to our
 117                                            caller.  */
 118                                         return -errno;
 119                         }
 120                 } while (*p++ != '\0');
 121
 122                 /* We tried every element and none of them worked.  */
 123                 if (got_eacces)
 124                         /* At least one failure was due to permissions, so report that
 125                            error.  */
 126                         return -EACCES;
 127         }
 128
 129         /* Return the error from the last attempt (probably ENOENT).  */
 130         return -errno;
 131 }
 132 #ifdef TEST
 133 int main(int argc, char**argv)
 134 {
 135         char buf[PATH_MAX];
 136         int ret;
 137         argc--;
 138         if (!argc) {
 139                 fprintf(stderr, "Not enough arguments\n");
 140                 return 1;
 141         }
 142         argv++;
 143         if (ret = execvp_noalloc(buf, argv[0], argv)) {
 144                 errno = -ret;
 145                 perror("execvp_noalloc");
 146         }
 147         return 0;
 148 }
 149 #endif