src/readlink.c

   1 /* readlink -- display value of a symbolic link.
   2    Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  17
  18 /* Written by Dmitry V. Levin */
  19
  20 #include <config.h>
  21 #include <stdio.h>
  22 #include <getopt.h>
  23 #include <sys/types.h>
  24
  25 #include "system.h"
  26 #include "canonicalize.h"
  27 #include "error.h"
  28 #include "xreadlink.h"
  29 #include "quote.h"
  30
  31 /* The official name of this program (e.g., no `g' prefix).  */
  32 #define PROGRAM_NAME "readlink"
  33
  34 #define AUTHORS "Dmitry V. Levin"
  35
  36 /* Name this program was run with.  */
  37 char *program_name;
  38
  39 /* If true, do not output the trailing newline.  */
  40 static bool no_newline;
  41
  42 /* If true, report error messages.  */
  43 static bool verbose;
  44
  45 static struct option const longopts[] =
  46 {
  47   {"canonicalize", no_argument, NULL, 'f'},
  48   {"canonicalize-existing", no_argument, NULL, 'e'},
  49   {"canonicalize-missing", no_argument, NULL, 'm'},
  50   {"no-newline", no_argument, NULL, 'n'},
  51   {"quiet", no_argument, NULL, 'q'},
  52   {"silent", no_argument, NULL, 's'},
  53   {"verbose", no_argument, NULL, 'v'},
  54   {GETOPT_HELP_OPTION_DECL},
  55   {GETOPT_VERSION_OPTION_DECL},
  56   {NULL, 0, NULL, 0}
  57 };
  58
  59 void
  60 usage (int status)
  61 {
  62   if (status != EXIT_SUCCESS)
  63     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  64              program_name);
  65   else
  66     {
  67       printf (_("Usage: %s [OPTION]... FILE\n"), program_name);
  68       fputs (_("Display value of a symbolic link on standard output.\n\n"),
  69              stdout);
  70       fputs (_("\
  71   -f, --canonicalize            canonicalize by following every symlink in\n\
  72                                 every component of the given name recursively;\n\
  73                                 all but the last component must exist\n\
  74   -e, --canonicalize-existing   canonicalize by following every symlink in\n\
  75                                 every component of the given name recursively,\n\
  76                                 all components must exist\n\
  77 "), stdout);
  78       fputs (_("\
  79   -m, --canonicalize-missing    canonicalize by following every symlink in\n\
  80                                 every component of the given name recursively,\n\
  81                                 without requirements on components existence\n\
  82   -n, --no-newline              do not output the trailing newline\n\
  83   -q, --quiet,\n\
  84   -s, --silent                  suppress most error messages\n\
  85   -v, --verbose                 report error messages\n\
  86 "), stdout);
  87       fputs (HELP_OPTION_DESCRIPTION, stdout);
  88       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  89       emit_bug_reporting_address ();
  90     }
  91   exit (status);
  92 }
  93
  94 int
  95 main (int argc, char **argv)
  96 {
  97   /* If not -1, use this method to canonicalize.  */
  98   int can_mode = -1;
  99
 100   /* File name to canonicalize.  */
 101   const char *fname;
 102
 103   /* Result of canonicalize.  */
 104   char *value;
 105
 106   int optc;
 107
 108   initialize_main (&argc, &argv);
 109   program_name = argv[0];
 110   setlocale (LC_ALL, "");
 111   bindtextdomain (PACKAGE, LOCALEDIR);
 112   textdomain (PACKAGE);
 113
 114   atexit (close_stdout);
 115
 116   while ((optc = getopt_long (argc, argv, "efmnqsv", longopts, NULL)) != -1)
 117     {
 118       switch (optc)
 119         {
 120         case 'e':
 121           can_mode = CAN_EXISTING;
 122           break;
 123         case 'f':
 124           can_mode = CAN_ALL_BUT_LAST;
 125           break;
 126         case 'm':
 127           can_mode = CAN_MISSING;
 128           break;
 129         case 'n':
 130           no_newline = true;
 131           break;
 132         case 'q':
 133         case 's':
 134           verbose = false;
 135           break;
 136         case 'v':
 137           verbose = true;
 138           break;
 139         case_GETOPT_HELP_CHAR;
 140         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 141         default:
 142           usage (EXIT_FAILURE);
 143         }
 144     }
 145
 146   if (optind >= argc)
 147     {
 148       error (0, 0, _("missing operand"));
 149       usage (EXIT_FAILURE);
 150     }
 151
 152   fname = argv[optind++];
 153
 154   if (optind < argc)
 155     {
 156       error (0, 0, _("extra operand %s"), quote (argv[optind]));
 157       usage (EXIT_FAILURE);
 158     }
 159
 160   value = (can_mode != -1
 161            ? canonicalize_filename_mode (fname, can_mode)
 162            : xreadlink (fname));
 163   if (value)
 164     {
 165       printf ("%s%s", value, (no_newline ? "" : "\n"));
 166       free (value);
 167       return EXIT_SUCCESS;
 168     }
 169
 170   if (verbose)
 171     error (EXIT_FAILURE, errno, "%s", fname);
 172
 173   return EXIT_FAILURE;
 174 }