lib/libc/src/strlcpy.c

/*
 * SPDX-License-Identifier: ISC
 * SPDX-FileCopyrightText: Copyright Todd C. Miller <Todd.Miller@courtesan.com>
 * SPDX-FileCopyrightText: Copyright TF-RMM Contributors.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * OpenBSD: strlcpy.c,v 1.12 2015/01/15 03:54:12 millert Exp $
 */

#include <stdint.h>
#include <string.h>

/*
 * Copy string src to buffer dst of size dsize.  At most dsize-1
 * chars will be copied.  Always NUL terminates (unless dsize == 0).
 * Returns strlen(src); if retval >= dsize, truncation occurred.
 */
size_t strlcpy(char *dst, const char *src, size_t dsize)
{
	const char *osrc = src;
	size_t nleft = dsize;

	/* Copy as many bytes as will fit. */
	if (nleft != 0UL) {
		while (--nleft != 0UL) {
			*dst++ = *src++;
			if (*(dst - 1) == '\0') {
				break;
			}
		}
	}

	/* Not enough room in dst, add NUL and traverse rest of src. */
	if (nleft == 0UL) {
		if (dsize != 0UL) {
			*dst = '\0'; /* NUL-terminate dst */
		}
		while (*src++) {
			;
		}
	}

	return (src - osrc - 1); /* count does not include NUL */
}