release/src/router/busybox/libbb/executable.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) 2006 Gabriel Somlo <somlo at cmu.edu>
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9
  10 #include "libbb.h"
  11
  12 /* check if path points to an executable file;
  13  * return 1 if found;
  14  * return 0 otherwise;
  15  */
  16 int FAST_FUNC file_is_executable(const char *name)
  17 {
  18         struct stat s;
  19         return (!access(name, X_OK) && !stat(name, &s) && S_ISREG(s.st_mode));
  20 }
  21
  22 /* search (*PATHp) for an executable file;
  23  * return allocated string containing full path if found;
  24  *  PATHp points to the component after the one where it was found
  25  *  (or NULL),
  26  *  you may call find_executable again with this PATHp to continue
  27  *  (if it's not NULL).
  28  * return NULL otherwise; (PATHp is undefined)
  29  * in all cases (*PATHp) contents will be trashed (s/:/NUL/).
  30  */
  31 char* FAST_FUNC find_executable(const char *filename, char **PATHp)
  32 {
  33         /* About empty components in $PATH:
  34          * http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html
  35          * 8.3 Other Environment Variables - PATH
  36          * A zero-length prefix is a legacy feature that indicates the current
  37          * working directory. It appears as two adjacent colons ( "::" ), as an
  38          * initial colon preceding the rest of the list, or as a trailing colon
  39          * following the rest of the list.
  40          */
  41         char *p, *n;
  42
  43         p = *PATHp;
  44         while (p) {
  45                 n = strchr(p, ':');
  46                 if (n)
  47                         *n++ = '\0';
  48                 p = concat_path_file(
  49                         p[0] ? p : ".", /* handle "::" case */
  50                         filename
  51                 );
  52                 if (file_is_executable(p)) {
  53                         *PATHp = n;
  54                         return p;
  55                 }
  56                 free(p);
  57                 p = n;
  58         } /* on loop exit p == NULL */
  59         return p;
  60 }
  61
  62 /* search $PATH for an executable file;
  63  * return 1 if found;
  64  * return 0 otherwise;
  65  */
  66 int FAST_FUNC executable_exists(const char *filename)
  67 {
  68         char *path = xstrdup(getenv("PATH"));
  69         char *tmp = path;
  70         char *ret = find_executable(filename, &tmp);
  71         free(path);
  72         free(ret);
  73         return ret != NULL;
  74 }
  75
  76 #if ENABLE_FEATURE_PREFER_APPLETS
  77 /* just like the real execvp, but try to launch an applet named 'file' first */
  78 int FAST_FUNC BB_EXECVP(const char *file, char *const argv[])
  79 {
  80         if (find_applet_by_name(file) >= 0)
  81                 execvp(bb_busybox_exec_path, argv);
  82         return execvp(file, argv);
  83 }
  84 #endif
  85
  86 int FAST_FUNC BB_EXECVP_or_die(char **argv)
  87 {
  88         BB_EXECVP(argv[0], argv);
  89         /* SUSv3-mandated exit codes */
  90         xfunc_error_retval = (errno == ENOENT) ? 127 : 126;
  91         bb_perror_msg_and_die("can't execute '%s'", argv[0]);
  92 }