strlcat.c

/*      $NetBSD: strlcat.c,v 1.3 2007/06/04 18:19:27 christos Exp $     */
/*      $OpenBSD: strlcat.c,v 1.10 2003/04/12 21:56:39 millert Exp $    */

/*
 * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
 *
 * 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 TODD C. MILLER DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL TODD C. MILLER 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.
 */

#if !defined(_KERNEL) && !defined(_STANDALONE)
#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#else
#include "config.h"
#endif

#if defined(LIBC_SCCS) && !defined(lint)
#endif /* LIBC_SCCS and not lint */

#ifdef _LIBC
#include "namespace.h"
#endif
#include <sys/types.h>
#include <assert.h>
#include <string.h>

#ifdef _LIBC
# ifdef __weak_alias
__weak_alias(strlcat, _strlcat)
# endif
#endif

#else
#include <lib/libkern/libkern.h>
#endif /* !_KERNEL && !_STANDALONE */

#if !HAVE_STRLCAT
/*
 * Appends src to string dst of size siz (unlike strncat, siz is the
 * full size of dst, not space left).  At most siz-1 characters
 * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
 * Returns strlen(src) + MIN(siz, strlen(initial dst)).
 * If retval >= siz, truncation occurred.
 */
size_t
strlcat(char *dst, const char *src, size_t siz)
{
        char *d = dst;
        const char *s = src;
        size_t n = siz;
        size_t dlen;

        _DIAGASSERT(dst != NULL);
        _DIAGASSERT(src != NULL);

        /* Find the end of dst and adjust bytes left but don't go past end */
        while (n-- != 0 && *d != '\0')
                d++;
        dlen = d - dst;
        n = siz - dlen;

        if (n == 0)
                return(dlen + strlen(s));
        while (*s != '\0') {
                if (n != 1) {
                        *d++ = *s;
                        n--;
                }
                s++;
        }
        *d = '\0';

        return(dlen + (s - src));       /* count does not include NUL */
}
#endif