lib/strnlen.c

   1 /* Find the length of STRING, but scan at most MAXLEN characters.
   2    Copyright (C) 1996, 1997, 1998, 2000-2002 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #if HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #if HAVE_STRING_H
  25 # if !STDC_HEADERS && HAVE_MEMORY_H
  26 #  include <memory.h>
  27 # endif
  28 /* Temporarily redefine strnlen so that an inconsistent prototype
  29    (on at least AIX4.3.2.0 w/gcc-2.95.3) doesn't cause trouble.  */
  30 # define strnlen system_strnlen
  31 # include <string.h>
  32 # undef strnlen
  33 #else
  34 # include <strings.h>
  35 #endif
  36
  37 #ifndef HAVE_DECL_MEMCHR
  38 "this configure-time declaration test was not run"
  39 #endif
  40 #if !HAVE_DECL_MEMCHR
  41 char *memchr ();
  42 #endif
  43
  44 #undef __strnlen
  45 #undef strnlen
  46
  47 #ifndef weak_alias
  48 # define __strnlen strnlen
  49 #endif
  50
  51 /* Find the length of STRING, but scan at most MAXLEN characters.
  52    If no '\0' terminator is found in that many characters, return MAXLEN.  */
  53
  54 size_t
  55 __strnlen (const char *string, size_t maxlen)
  56 {
  57   const char *end = memchr (string, '\0', maxlen);
  58   return end ? (size_t) (end - string) : maxlen;
  59 }
  60 #ifdef weak_alias
  61 weak_alias (__strnlen, strnlen)
  62 #endif