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/* vi: set sw=4 ts=4: */
/*
* Mini readlink implementation for busybox
*
* Copyright (C) 2000,2001 Matt Kraai <kraai@alumni.carnegiemellon.edu>
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config READLINK
//config: bool "readlink (4 kb)"
//config: default y
//config: help
//config: This program reads a symbolic link and returns the name
//config: of the file it points to
//config:
//config:config FEATURE_READLINK_FOLLOW
//config: bool "Enable canonicalization by following all symlinks (-f)"
//config: default y
//config: depends on READLINK
//config: help
//config: Enable the readlink option (-f).
//applet:IF_READLINK(APPLET_NOFORK(readlink, readlink, BB_DIR_USR_BIN, BB_SUID_DROP, readlink))
//kbuild:lib-$(CONFIG_READLINK) += readlink.o
//usage:#define readlink_trivial_usage
//usage: IF_FEATURE_READLINK_FOLLOW("[-fnv] ") "FILE"
//usage:#define readlink_full_usage "\n\n"
//usage: "Display the value of a symlink"
//usage: IF_FEATURE_READLINK_FOLLOW( "\n"
//usage: "\n -f Canonicalize by following all symlinks"
//usage: "\n -n Don't add newline"
//usage: "\n -v Verbose"
//usage: )
#include "libbb.h"
/*
* # readlink --version
* readlink (GNU coreutils) 6.10
* # readlink --help
* -f, --canonicalize
* canonicalize by following every symlink in
* every component of the given name recursively;
* all but the last component must exist
* -e, --canonicalize-existing
* canonicalize by following every symlink in
* every component of the given name recursively,
* all components must exist
* -m, --canonicalize-missing
* canonicalize by following every symlink in
* every component of the given name recursively,
* without requirements on components existence
* -n, --no-newline do not output the trailing newline
* -q, --quiet, -s, --silent suppress most error messages
* -v, --verbose report error messages
*
* bbox supports: -f (partially) -n -v (fully), -q -s (accepts but ignores)
* Note: we export the -f flag, but our -f behaves like coreutils' -e.
* Unfortunately, there isn't a C lib function we can leverage to get this
* behavior which means we'd have to implement the full stack ourselves :(.
*/
int readlink_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int readlink_main(int argc UNUSED_PARAM, char **argv)
{
char *buf;
char *fname;
IF_FEATURE_READLINK_FOLLOW(
unsigned opt;
/* We need exactly one non-option argument. */
opt = getopt32(argv, "^" "fnvsq" "\0" "=1");
fname = argv[optind];
)
IF_NOT_FEATURE_READLINK_FOLLOW(
const unsigned opt = 0;
if (argc != 2) bb_show_usage();
fname = argv[1];
)
/* compat: coreutils readlink reports errors silently via exit code */
if (!(opt & 4)) /* not -v */
logmode = LOGMODE_NONE;
/* NOFORK: only one alloc is allowed; must free */
if (opt & 1) { /* -f */
buf = xmalloc_realpath_coreutils(fname);
} else {
buf = xmalloc_readlink_or_warn(fname);
}
if (!buf)
return EXIT_FAILURE;
printf((opt & 2) ? "%s" : "%s\n", buf);
free(buf);
fflush_stdout_and_exit(EXIT_SUCCESS);
}
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