/*  $OpenBSD: strlcat.c,v 1.15 2015/03/02 21:41:08 millert Exp $  */

/*

 * Copyright (c) 1998, 2015 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 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.

 */

#include "ruby/missing.h"

#include <sys/types.h>

#include <string.h>

/*

 * Appends src to string dst of size dsize (unlike strncat, dsize is the

 * full size of dst, not space left).  At most dsize-1 characters

 * will be copied.  Always NUL terminates (unless dsize <= strlen(dst)).

 * Returns strlen(src) + MIN(dsize, strlen(initial dst)).

 * If retval >= dsize, truncation occurred.

 */

size_t

strlcat(char *dst, const char *src, size_t dsize)

{

  const char *odst = dst;

  const char *osrc = src;

  size_t n = dsize;

  size_t dlen;

  /* Find the end of dst and adjust bytes left but don't go past end. */

  while (n-- != 0 && *dst != '\0')

    dst++;

  dlen = dst - odst;

  n = dsize - dlen;

  if (n-- == 0)

    return(dlen + strlen(src));

  while (*src != '\0') {

    if (n != 0) {

      *dst++ = *src;

      n--;

    }

    src++;

  }

  *dst = '\0';

  return(dlen + (src - osrc));  /* count does not include NUL */

}