Merge pull request #2057 from donaldsharp/fix_1916

[mirror_frr.git] / lib / strlcpy.c

/* Copy a null-terminated string to a fixed-size buffer, with length checking.
 * Copyright (C) 2016 Free Software Foundation, Inc.
 * This file is part of the GNU C Library.
 *
 * The GNU C Library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * The GNU C Library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with the GNU C Library; if not, see
 * <http://www.gnu.org/licenses/>.
 */

/* adapted for Quagga from glibc patch submission originally from
 * Florian Weimer <fweimer@redhat.com>, 2016-05-18 */

#include <string.h>

#include "config.h"

#ifndef HAVE_STRLCPY
#undef strlcpy

size_t strlcpy(char *__restrict dest,
	       const char *__restrict src, size_t destsize);

size_t strlcpy(char *__restrict dest,
	       const char *__restrict src, size_t destsize)
{
	size_t src_length = strlen(src);

	if (__builtin_expect(src_length >= destsize, 0)) {
		if (destsize > 0) {
			/*
			 * Copy the leading portion of the string.  The last
			 * character is subsequently overwritten with the NUL
			 * terminator, but the destination destsize is usually
			 * a multiple of a small power of two, so writing it
			 * twice should be more efficient than copying an odd
			 * number of bytes.
			 */
			memcpy(dest, src, destsize);
			dest[destsize - 1] = '\0';
		}
	} else
		/* Copy the string and its terminating NUL character.  */
		memcpy(dest, src, src_length + 1);
	return src_length;
}
#endif /* HAVE_STRLCPY */