debianutils/which.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Which implementation for busybox
   4  *
   5  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
   6  *
   7  * Licensed under the GPL v2, see the file LICENSE in this tarball.
   8  *
   9  * Based on which from debianutils
  10  */
  11
  12 #include "busybox.h"
  13 #include <string.h>
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <unistd.h>
  17 #include <sys/stat.h>
  18
  19
  20 static int is_executable_file(const char const * a, struct stat *b)
  21 {
  22         return (!access(a,X_OK) && !stat(a, b) && S_ISREG(b->st_mode));
  23 }
  24
  25 int which_main(int argc, char **argv)
  26 {
  27         int status;
  28         size_t i, count;
  29         char *path_list;
  30
  31         if (argc <= 1 || **(argv + 1) == '-') {
  32                 bb_show_usage();
  33         }
  34         argc--;
  35
  36         path_list = getenv("PATH");
  37         if (path_list != NULL) {
  38                 size_t path_len = strlen(path_list);
  39                 char *new_list = NULL;
  40                 count = 1;
  41
  42                 for (i = 0; i <= path_len; i++) {
  43                         char *this_i = &path_list[i];
  44                         if (*this_i == ':') {
  45                                 /* ^::[^:] == \.: */
  46                                 if (!i && (*(this_i + 1) == ':')) {
  47                                         *this_i = '.';
  48                                         continue;
  49                                 }
  50                                 *this_i = 0;
  51                                 count++;
  52                                 /* ^:[^:] == \.0 and [^:]::[^:] == 0\.0 and [^:]:$ == 0\.0 */
  53                                 if (!i || (*(this_i + 1) == ':') || (i == path_len-1)) {
  54                                         new_list = xrealloc(new_list, path_len += 1);
  55                                         if (i) {
  56                                                 memmove(&new_list[i+2], &path_list[i+1], path_len-i);
  57                                                 new_list[i+1] = '.';
  58                                                 memmove(new_list, path_list, i);
  59                                         } else {
  60                                                 memmove(&new_list[i+1], &path_list[i], path_len-i);
  61                                                 new_list[i] = '.';
  62                                         }
  63                                         path_list = new_list;
  64                                 }
  65                         }
  66                 }
  67         } else {
  68                 path_list = "/bin\0/sbin\0/usr/bin\0/usr/sbin\0/usr/local/bin";
  69                 count = 5;
  70         }
  71
  72         status = EXIT_SUCCESS;
  73         while (argc-- > 0) {
  74                 struct stat stat_b;
  75                 char *buf;
  76                 char *path_n;
  77                 int found = 0;
  78
  79                 argv++;
  80                 path_n = path_list;
  81                 buf = *argv;
  82
  83                 /* if filename is either absolute or contains slashes,
  84                  * stat it */
  85                 if (strchr(buf, '/') != NULL && is_executable_file(buf, &stat_b)) {
  86                         found++;
  87                 } else {
  88                         /* Couldn't access file and file doesn't contain slashes */
  89                         for (i = 0; i < count; i++) {
  90                                 buf = concat_path_file(path_n, *argv);
  91                                 if (is_executable_file(buf, &stat_b)) {
  92                                         found++;
  93                                         break;
  94                                 }
  95                                 free(buf);
  96                                 path_n += (strlen(path_n) + 1);
  97                         }
  98                 }
  99                 if (found) {
 100                         puts(buf);
 101                 } else {
 102                         status = EXIT_FAILURE;
 103                 }
 104         }
 105         bb_fflush_stdout_and_exit(status);
 106 }