release/src/router/busybox/libbb/execable.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 execable_file(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_execable 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_execable(const char *filename, char **PATHp)
  32 {
  33         char *p, *n;
  34
  35         p = *PATHp;
  36         while (p) {
  37                 n = strchr(p, ':');
  38                 if (n)
  39                         *n++ = '\0';
  40                 if (*p != '\0') { /* it's not a PATH="foo::bar" situation */
  41                         p = concat_path_file(p, filename);
  42                         if (execable_file(p)) {
  43                                 *PATHp = n;
  44                                 return p;
  45                         }
  46                         free(p);
  47                 }
  48                 p = n;
  49         } /* on loop exit p == NULL */
  50         return p;
  51 }
  52
  53 /* search $PATH for an executable file;
  54  * return 1 if found;
  55  * return 0 otherwise;
  56  */
  57 int FAST_FUNC exists_execable(const char *filename)
  58 {
  59         char *path = xstrdup(getenv("PATH"));
  60         char *tmp = path;
  61         char *ret = find_execable(filename, &tmp);
  62         free(path);
  63         if (ret) {
  64                 free(ret);
  65                 return 1;
  66         }
  67         return 0;
  68 }
  69
  70 #if ENABLE_FEATURE_PREFER_APPLETS
  71 /* just like the real execvp, but try to launch an applet named 'file' first */
  72 int FAST_FUNC BB_EXECVP(const char *file, char *const argv[])
  73 {
  74         if (find_applet_by_name(file) >= 0)
  75                 execvp(bb_busybox_exec_path, argv);
  76         return execvp(file, argv);
  77 }
  78 #endif
  79
  80 int FAST_FUNC BB_EXECVP_or_die(char **argv)
  81 {
  82         BB_EXECVP(argv[0], argv);
  83         /* SUSv3-mandated exit codes */
  84         xfunc_error_retval = (errno == ENOENT) ? 127 : 126;
  85         bb_perror_msg_and_die("can't execute '%s'", argv[0]);
  86 }