src/safe_strncat.c

   1 /*
   2     Copyright (C) 2011 Ben Kibbey <bjk@luxsci.net>
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02110-1301  USA
  17 */
  18 #ifdef HAVE_CONFIG_H
  19 #include <config.h>
  20 #endif
  21
  22 #include <string.h>
  23 #include <stdio.h>
  24
  25 size_t safe_strncat(char *dst, const char *src, size_t n)
  26 {
  27     char *dp;
  28     const char *sp;
  29     size_t len;
  30
  31     if (!n)
  32         return strlen(dst)+strlen(src)+1;
  33
  34     for (dp = dst, len = 0; *dp; dp++, len++);
  35
  36     for (sp = src; *sp && len < n-1; len++, sp++)
  37         *dp++ = *sp;
  38
  39     *dp = 0;
  40
  41     if (*sp) {
  42         while (*sp++)
  43             len++;
  44     }
  45
  46     return len;
  47 }