common/lib/libc/string/strlcat.c

   1 /*      $NetBSD: strlcat.c,v 1.4 2013/01/23 07:57:27 matt Exp $ */
   2 /*      $OpenBSD: strlcat.c,v 1.10 2003/04/12 21:56:39 millert Exp $    */
   3
   4 /*
   5  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
   6  *
   7  * Permission to use, copy, modify, and distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND TODD C. MILLER DISCLAIMS ALL
  12  * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  13  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL TODD C. MILLER BE LIABLE
  14  * FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  16  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  17  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 #if !defined(_KERNEL) && !defined(_STANDALONE)
  21 #if HAVE_NBTOOL_CONFIG_H
  22 #include "nbtool_config.h"
  23 #endif
  24
  25 #include <sys/cdefs.h>
  26 #if defined(LIBC_SCCS) && !defined(lint)
  27 __RCSID("$NetBSD: strlcat.c,v 1.4 2013/01/23 07:57:27 matt Exp $");
  28 #endif /* LIBC_SCCS and not lint */
  29
  30 #ifdef _LIBC
  31 #include "namespace.h"
  32 #endif
  33 #include <sys/types.h>
  34 #include <assert.h>
  35 #include <string.h>
  36
  37 #ifdef _LIBC
  38 # ifdef __weak_alias
  39 __weak_alias(strlcat, _strlcat)
  40 # endif
  41 #endif
  42
  43 #else
  44 #include <lib/libkern/libkern.h>
  45 #endif /* !_KERNEL && !_STANDALONE */
  46
  47 #if !HAVE_STRLCAT
  48 /*
  49  * Appends src to string dst of size siz (unlike strncat, siz is the
  50  * full size of dst, not space left).  At most siz-1 characters
  51  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
  52  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
  53  * If retval >= siz, truncation occurred.
  54  */
  55 size_t
  56 strlcat(char *dst, const char *src, size_t siz)
  57 {
  58 #if 1
  59         char *d = dst;
  60         const char *s = src;
  61         size_t n = siz;
  62         size_t dlen;
  63
  64         _DIAGASSERT(dst != NULL);
  65         _DIAGASSERT(src != NULL);
  66
  67         /* Find the end of dst and adjust bytes left but don't go past end */
  68         while (n-- != 0 && *d != '\0')
  69                 d++;
  70         dlen = d - dst;
  71         n = siz - dlen;
  72
  73         if (n == 0)
  74                 return(dlen + strlen(s));
  75         while (*s != '\0') {
  76                 if (n != 1) {
  77                         *d++ = *s;
  78                         n--;
  79                 }
  80                 s++;
  81         }
  82         *d = '\0';
  83
  84         return(dlen + (s - src));       /* count does not include NUL */
  85 #else
  86         _DIAGASSERT(dst != NULL);
  87         _DIAGASSERT(src != NULL);
  88
  89         /*
  90          * Find length of string in dst (maxing out at siz).
  91          */
  92         size_t dlen = strnlen(dst, siz);
  93
  94         /*
  95          * Copy src into any remaining space in dst (truncating if needed).
  96          * Note strlcpy(dst, src, 0) returns strlen(src).
  97          */
  98         return dlen + strlcpy(dst + dlen, src, siz - dlen);
  99 #endif
 100 }
 101 #endif