release/src/router/busybox/coreutils/readlink.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini readlink implementation for busybox
   4  *
   5  * Copyright (C) 2000,2001 Matt Kraai <kraai@alumni.carnegiemellon.edu>
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9
  10 //usage:#define readlink_trivial_usage
  11 //usage:        IF_FEATURE_READLINK_FOLLOW("[-fnv] ") "FILE"
  12 //usage:#define readlink_full_usage "\n\n"
  13 //usage:       "Display the value of a symlink"
  14 //usage:        IF_FEATURE_READLINK_FOLLOW( "\n"
  15 //usage:     "\n        -f      Canonicalize by following all symlinks"
  16 //usage:     "\n        -n      Don't add newline"
  17 //usage:     "\n        -v      Verbose"
  18 //usage:        )
  19
  20 #include "libbb.h"
  21
  22 /*
  23  * # readlink --version
  24  * readlink (GNU coreutils) 6.10
  25  * # readlink --help
  26  *   -f, --canonicalize
  27  *      canonicalize by following every symlink in
  28  *      every component of the given name recursively;
  29  *      all but the last component must exist
  30  *   -e, --canonicalize-existing
  31  *      canonicalize by following every symlink in
  32  *      every component of the given name recursively,
  33  *      all components must exist
  34  *   -m, --canonicalize-missing
  35  *      canonicalize by following every symlink in
  36  *      every component of the given name recursively,
  37  *      without requirements on components existence
  38  *   -n, --no-newline              do not output the trailing newline
  39  *   -q, --quiet, -s, --silent     suppress most error messages
  40  *   -v, --verbose                 report error messages
  41  *
  42  * bbox supports: -f -n -v (fully), -q -s (accepts but ignores)
  43  */
  44
  45 int readlink_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  46 int readlink_main(int argc UNUSED_PARAM, char **argv)
  47 {
  48         char *buf;
  49         char *fname;
  50
  51         IF_FEATURE_READLINK_FOLLOW(
  52                 unsigned opt;
  53                 /* We need exactly one non-option argument.  */
  54                 opt_complementary = "=1";
  55                 opt = getopt32(argv, "fnvsq");
  56                 fname = argv[optind];
  57         )
  58         IF_NOT_FEATURE_READLINK_FOLLOW(
  59                 const unsigned opt = 0;
  60                 if (argc != 2) bb_show_usage();
  61                 fname = argv[1];
  62         )
  63
  64         /* compat: coreutils readlink reports errors silently via exit code */
  65         if (!(opt & 4)) /* not -v */
  66                 logmode = LOGMODE_NONE;
  67
  68         if (opt & 1) { /* -f */
  69                 buf = xmalloc_realpath(fname);
  70         } else {
  71                 buf = xmalloc_readlink_or_warn(fname);
  72         }
  73
  74         if (!buf)
  75                 return EXIT_FAILURE;
  76         printf((opt & 2) ? "%s" : "%s\n", buf);
  77
  78         if (ENABLE_FEATURE_CLEAN_UP)
  79                 free(buf);
  80
  81         fflush_stdout_and_exit(EXIT_SUCCESS);
  82 }