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/* readlink -- display value of a symbolic link.
Copyright (C) 2002-2020 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 <https://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 (on by default)\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 (PROGRAM_NAME);
}
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", quotef (fname));
}
}
return status;
}
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