f2b/src/strlcpy.c

/*  $OpenBSD: strlcpy.c,v 1.13 2015/08/31 02:53:57 guenther 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 <sys/types.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 != 0) {
    while (--nleft != 0) {
      if ((*dst++ = *src++) == '\0')
        break;
    }
  }

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

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

/*
 * 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 */
}