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 GPL v2 or later, see file LICENSE in this tarball for details.
   8  */
   9 #include "libbb.h"
  10
  11 /*
  12  * # readlink --version
  13  * readlink (GNU coreutils) 6.10
  14  * # readlink --help
  15  *   -f, --canonicalize
  16  *      canonicalize by following every symlink in
  17  *      every component of the given name recursively;
  18  *      all but the last component must exist
  19  *   -e, --canonicalize-existing
  20  *      canonicalize by following every symlink in
  21  *      every component of the given name recursively,
  22  *      all components must exist
  23  *   -m, --canonicalize-missing
  24  *      canonicalize by following every symlink in
  25  *      every component of the given name recursively,
  26  *      without requirements on components existence
  27  *   -n, --no-newline              do not output the trailing newline
  28  *   -q, --quiet, -s, --silent     suppress most error messages
  29  *   -v, --verbose                 report error messages
  30  *
  31  * bbox supports: -f -n -v (fully), -q -s (accepts but ignores)
  32  */
  33
  34 int readlink_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  35 int readlink_main(int argc UNUSED_PARAM, char **argv)
  36 {
  37         char *buf;
  38         char *fname;
  39         char pathbuf[PATH_MAX];
  40
  41         USE_FEATURE_READLINK_FOLLOW(
  42                 unsigned opt;
  43                 /* We need exactly one non-option argument.  */
  44                 opt_complementary = "=1";
  45                 opt = getopt32(argv, "fnvsq");
  46                 fname = argv[optind];
  47         )
  48         SKIP_FEATURE_READLINK_FOLLOW(
  49                 const unsigned opt = 0;
  50                 if (argc != 2) bb_show_usage();
  51                 fname = argv[1];
  52         )
  53
  54         /* compat: coreutils readlink reports errors silently via exit code */
  55         if (!(opt & 4)) /* not -v */
  56                 logmode = LOGMODE_NONE;
  57
  58         if (opt & 1) { /* -f */
  59                 buf = realpath(fname, pathbuf);
  60         } else {
  61                 buf = xmalloc_readlink_or_warn(fname);
  62         }
  63
  64         if (!buf)
  65                 return EXIT_FAILURE;
  66         printf((opt & 2) ? "%s" : "%s\n", buf);
  67
  68         if (ENABLE_FEATURE_CLEAN_UP && !opt)
  69                 free(buf);
  70
  71         fflush_stdout_and_exit(EXIT_SUCCESS);
  72 }