summaryrefslogtreecommitdiff
path: root/src/readlink.c
blob: d63f07b40578c111d7a59b43abf1098acde021e8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
/* readlink -- display value of a symbolic link.
   Copyright (C) 2002-2014 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Written by Dmitry V. Levin */

#include <config.h>
#include <stdio.h>
#include <getopt.h>
#include <sys/types.h>

#include "system.h"
#include "canonicalize.h"
#include "error.h"
#include "areadlink.h"

/* The official name of this program (e.g., no 'g' prefix).  */
#define PROGRAM_NAME "readlink"

#define AUTHORS proper_name ("Dmitry V. Levin")

/* If true, do not output the trailing newline.  */
static bool no_newline;

/* If true, report error messages.  */
static bool verbose;

static struct option const longopts[] =
{
  {"canonicalize", no_argument, NULL, 'f'},
  {"canonicalize-existing", no_argument, NULL, 'e'},
  {"canonicalize-missing", no_argument, NULL, 'm'},
  {"no-newline", no_argument, NULL, 'n'},
  {"quiet", no_argument, NULL, 'q'},
  {"silent", no_argument, NULL, 's'},
  {"verbose", no_argument, NULL, 'v'},
  {"zero", no_argument, NULL, 'z'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    emit_try_help ();
  else
    {
      printf (_("Usage: %s [OPTION]... FILE...\n"), program_name);
      fputs (_("Print value of a symbolic link or canonical file name\n\n"),
             stdout);
      fputs (_("\
  -f, --canonicalize            canonicalize by following every symlink in\n\
                                every component of the given name recursively;\
\n\
                                all but the last component must exist\n\
  -e, --canonicalize-existing   canonicalize by following every symlink in\n\
                                every component of the given name recursively,\
\n\
                                all components must exist\n\
"), stdout);
      fputs (_("\
  -m, --canonicalize-missing    canonicalize by following every symlink in\n\
                                every component of the given name recursively,\
\n\
                                without requirements on components existence\n\
  -n, --no-newline              do not output the trailing delimiter\n\
  -q, --quiet,\n\
  -s, --silent                  suppress most error messages\n\
  -v, --verbose                 report error messages\n\
  -z, --zero                    end each output line with NUL, not newline\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      emit_ancillary_info ();
    }
  exit (status);
}

int
main (int argc, char **argv)
{
  /* If not -1, use this method to canonicalize.  */
  int can_mode = -1;
  int status = EXIT_SUCCESS;
  int optc;
  bool use_nuls = false;

  initialize_main (&argc, &argv);
  set_program_name (argv[0]);
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  while ((optc = getopt_long (argc, argv, "efmnqsvz", longopts, NULL)) != -1)
    {
      switch (optc)
        {
        case 'e':
          can_mode = CAN_EXISTING;
          break;
        case 'f':
          can_mode = CAN_ALL_BUT_LAST;
          break;
        case 'm':
          can_mode = CAN_MISSING;
          break;
        case 'n':
          no_newline = true;
          break;
        case 'q':
        case 's':
          verbose = false;
          break;
        case 'v':
          verbose = true;
          break;
        case 'z':
          use_nuls = true;
          break;
        case_GETOPT_HELP_CHAR;
        case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
        default:
          usage (EXIT_FAILURE);
        }
    }

  if (optind >= argc)
    {
      error (0, 0, _("missing operand"));
      usage (EXIT_FAILURE);
    }

  if (argc - optind > 1)
    {
      if (no_newline)
        error (0, 0, _("ignoring --no-newline with multiple arguments"));
      no_newline = false;
    }

  for (; optind < argc; ++optind)
    {
      const char *fname = argv[optind];
      char *value = (can_mode != -1
                     ? canonicalize_filename_mode (fname, can_mode)
                     : areadlink_with_size (fname, 63));
      if (value)
        {
          fputs (value, stdout);
          if (! no_newline)
            putchar (use_nuls ? '\0' : '\n');
          free (value);
        }
      else
        {
          status = EXIT_FAILURE;
          if (verbose)
            error (0, errno, "%s", fname);
        }
    }

  return status;
}