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 <string.h>
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <sys/stat.h>
  17 #include "busybox.h"
  18
  19 int which_main(int argc, char **argv)
  20 {
  21         int status = EXIT_SUCCESS;
  22         size_t i, count;
  23         char *path_list;
  24
  25         if (argc <= 1 || **(argv + 1) == '-') {
  26                 bb_show_usage();
  27         }
  28         argc--;
  29
  30         path_list = getenv("PATH");
  31         if (path_list != NULL) {
  32                 size_t path_len = bb_strlen(path_list);
  33                 char *new_list = NULL;
  34                 count = 1;
  35
  36                 for (i = 0; i <= path_len; i++) {
  37                         char *this_i = &path_list[i];
  38                         if (*this_i == ':') {
  39                                 /* ^::[^:] == \.: */
  40                                 if (!i && (*(this_i + 1) == ':')) {
  41                                         *this_i = '.';
  42                                         continue;
  43                                 }
  44                                 *this_i = 0;
  45                                 count++;
  46                                 /* ^:[^:] == \.0 and [^:]::[^:] == 0\.0 and [^:]:$ == 0\.0 */
  47                                 if (!i || (*(this_i + 1) == ':') || (i == path_len-1)) {
  48                                         new_list = xrealloc(new_list, path_len += 1);
  49                                         if (i) {
  50                                                 memmove(&new_list[i+2], &path_list[i+1], path_len-i);
  51                                                 new_list[i+1] = '.';
  52                                                 memmove(new_list, path_list, i);
  53                                         } else {
  54                                                 memmove(&new_list[i+1], &path_list[i], path_len-i);
  55                                                 new_list[i] = '.';
  56                                         }
  57                                         path_list = new_list;
  58                                 }
  59                         }
  60                 }
  61         } else {
  62                 path_list = "/bin\0/sbin\0/usr/bin\0/usr/sbin\0/usr/local/bin";
  63                 count = 5;
  64         }
  65
  66         while (argc-- > 0) {
  67                 struct stat stat_b;
  68                 char *buf;
  69                 char *path_n;
  70                 char found = 0;
  71 #define is_executable_file(a, b) (!access(a,X_OK) && !stat(a, &b) && \
  72                 S_ISREG(b.st_mode))
  73
  74                 argv++;
  75                 path_n = path_list;
  76                 buf = *argv;
  77
  78                 /* if filename is either absolute or contains slashes,
  79                  * stat it */
  80                 if (strchr(buf, '/') != NULL && is_executable_file(buf, stat_b)) {
  81                         found = 1;
  82                 } else {
  83                         /* Couldn't access file and file doesn't contain slashes */
  84                         for (i = 0; i < count; i++) {
  85                                 buf = concat_path_file(path_n, *argv);
  86                                 if (is_executable_file(buf, stat_b)) {
  87                                         found = 1;
  88                                         break;
  89                                 }
  90                                 free(buf);
  91                                 path_n += (bb_strlen(path_n) + 1);
  92                         }
  93                 }
  94                 if (found) {
  95                         puts(buf);
  96                 } else {
  97                         status = EXIT_FAILURE;
  98                 }
  99         }
 100         bb_fflush_stdout_and_exit(status);
 101 }
 102
 103 /*
 104 Local Variables:
 105 c-file-style: "linux"
 106 c-basic-offset: 4
 107 tab-width: 4
 108 End:
 109 */