busybox/coreutils/readlink.c
Jeremie Koenig b175462422 readlink: use xmalloc_realpath()
Using realpath() directly with a non-NULL output buffer is unsafe because its
behavior is unspecified on systems which don't have PATH_MAX (ie. Hurd)

I beleive this also fixes a small bug whereby 'buf' would not be freed
on 'readlink -v' with ENABLE_FEATURE_CLEANUP.

Signed-off-by: Jeremie Koenig <jk@jk.fr.eu.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2010-07-19 00:43:05 +02:00

72 lines
1.9 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini readlink implementation for busybox
*
* Copyright (C) 2000,2001 Matt Kraai <kraai@alumni.carnegiemellon.edu>
*
* Licensed under GPL v2 or later, see file LICENSE in this tarball for details.
*/
#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 -n -v (fully), -q -s (accepts but ignores)
*/
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_complementary = "=1";
opt = getopt32(argv, "fnvsq");
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;
if (opt & 1) { /* -f */
buf = xmalloc_realpath(fname);
} else {
buf = xmalloc_readlink_or_warn(fname);
}
if (!buf)
return EXIT_FAILURE;
printf((opt & 2) ? "%s" : "%s\n", buf);
if (ENABLE_FEATURE_CLEAN_UP)
free(buf);
fflush_stdout_and_exit(EXIT_SUCCESS);
}