libc/string/strlcat.c

   1 /*
   2  * Copyright (C) 2002     Manuel Novoa III
   3  * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
   4  *
   5  * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
   6  */
   7
   8 /* OpenBSD function:
   9  * Append at most n-1-strlen(dst) chars from src to dst and nul-terminate dst.
  10  * Returns strlen(src) + strlen({original} dst), so truncation occurred if the
  11  * return val is >= n.
  12  * Note: If dst doesn't contain a nul in the first n chars, strlen(dst) is
  13  *       taken as n. */
  14
  15 #include "_string.h"
  16
  17 size_t strlcat(register char *__restrict dst,
  18                            register const char *__restrict src,
  19                            size_t n)
  20 {
  21         size_t len;
  22         char dummy[1];
  23
  24         len = 0;
  25
  26         while (1) {
  27                 if (len >= n) {
  28                         dst = dummy;
  29                         break;
  30                 }
  31                 if (!*dst) {
  32                         break;
  33                 }
  34                 ++dst;
  35                 ++len;
  36         }
  37
  38         while ((*dst = *src) != 0) {
  39                 if (++len < n) {
  40                         ++dst;
  41                 }
  42                 ++src;
  43         }
  44
  45         return len;
  46 }
  47 libc_hidden_def(strlcat)