1/* readlink -- display value of a symbolic link.
2   Copyright (C) 2002-2010 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 3 of the License, or
7   (at your option) 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, see <http://www.gnu.org/licenses/>.  */
16
17/* Written by Dmitry V. Levin */
18
19#include <config.h>
20#include <stdio.h>
21#include <getopt.h>
22#include <sys/types.h>
23
24#include "system.h"
25#include "canonicalize.h"
26#include "error.h"
27#include "areadlink.h"
28#include "quote.h"
29
30/* The official name of this program (e.g., no `g' prefix).  */
31#define PROGRAM_NAME "readlink"
32
33#define AUTHORS proper_name ("Dmitry V. Levin")
34
35/* If true, do not output the trailing newline.  */
36static bool no_newline;
37
38/* If true, report error messages.  */
39static bool verbose;
40
41static struct option const longopts[] =
42{
43  {"canonicalize", no_argument, NULL, 'f'},
44  {"canonicalize-existing", no_argument, NULL, 'e'},
45  {"canonicalize-missing", no_argument, NULL, 'm'},
46  {"no-newline", no_argument, NULL, 'n'},
47  {"quiet", no_argument, NULL, 'q'},
48  {"silent", no_argument, NULL, 's'},
49  {"verbose", no_argument, NULL, 'v'},
50  {GETOPT_HELP_OPTION_DECL},
51  {GETOPT_VERSION_OPTION_DECL},
52  {NULL, 0, NULL, 0}
53};
54
55void
56usage (int status)
57{
58  if (status != EXIT_SUCCESS)
59    fprintf (stderr, _("Try `%s --help' for more information.\n"),
60             program_name);
61  else
62    {
63      printf (_("Usage: %s [OPTION]... FILE\n"), program_name);
64      fputs (_("Print value of a symbolic link or canonical file name\n\n"),
65             stdout);
66      fputs (_("\
67  -f, --canonicalize            canonicalize by following every symlink in\n\
68                                every component of the given name recursively;\n\
69                                all but the last component must exist\n\
70  -e, --canonicalize-existing   canonicalize by following every symlink in\n\
71                                every component of the given name recursively,\n\
72                                all components must exist\n\
73"), stdout);
74      fputs (_("\
75  -m, --canonicalize-missing    canonicalize by following every symlink in\n\
76                                every component of the given name recursively,\n\
77                                without requirements on components existence\n\
78  -n, --no-newline              do not output the trailing newline\n\
79  -q, --quiet,\n\
80  -s, --silent                  suppress most error messages\n\
81  -v, --verbose                 report error messages\n\
82"), stdout);
83      fputs (HELP_OPTION_DESCRIPTION, stdout);
84      fputs (VERSION_OPTION_DESCRIPTION, stdout);
85      emit_ancillary_info ();
86    }
87  exit (status);
88}
89
90int
91main (int argc, char **argv)
92{
93  /* If not -1, use this method to canonicalize.  */
94  int can_mode = -1;
95
96  /* File name to canonicalize.  */
97  const char *fname;
98
99  /* Result of canonicalize.  */
100  char *value;
101
102  int optc;
103
104  initialize_main (&argc, &argv);
105  set_program_name (argv[0]);
106  setlocale (LC_ALL, "");
107  bindtextdomain (PACKAGE, LOCALEDIR);
108  textdomain (PACKAGE);
109
110  atexit (close_stdout);
111
112  while ((optc = getopt_long (argc, argv, "efmnqsv", longopts, NULL)) != -1)
113    {
114      switch (optc)
115        {
116        case 'e':
117          can_mode = CAN_EXISTING;
118          break;
119        case 'f':
120          can_mode = CAN_ALL_BUT_LAST;
121          break;
122        case 'm':
123          can_mode = CAN_MISSING;
124          break;
125        case 'n':
126          no_newline = true;
127          break;
128        case 'q':
129        case 's':
130          verbose = false;
131          break;
132        case 'v':
133          verbose = true;
134          break;
135        case_GETOPT_HELP_CHAR;
136        case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
137        default:
138          usage (EXIT_FAILURE);
139        }
140    }
141
142  if (optind >= argc)
143    {
144      error (0, 0, _("missing operand"));
145      usage (EXIT_FAILURE);
146    }
147
148  fname = argv[optind++];
149
150  if (optind < argc)
151    {
152      error (0, 0, _("extra operand %s"), quote (argv[optind]));
153      usage (EXIT_FAILURE);
154    }
155
156  value = (can_mode != -1
157           ? canonicalize_filename_mode (fname, can_mode)
158           : areadlink_with_size (fname, 63));
159  if (value)
160    {
161      printf ("%s%s", value, (no_newline ? "" : "\n"));
162      free (value);
163      return EXIT_SUCCESS;
164    }
165
166  if (verbose)
167    error (EXIT_FAILURE, errno, "%s", fname);
168
169  return EXIT_FAILURE;
170}
171