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