lib/strnlen.c

   1 /* Find the length of STRING, but scan at most MAXLEN characters.
   2    Copyright (C) 2005-2007, 2009-2025 Free Software Foundation, Inc.
   3
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation; either version 2.1 of the
   7    License, or (at your option) any later version.
   8
   9    This file 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 Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 #include <string.h>
  20
  21 /* Find the length of S, but scan at most MAXLEN bytes.
  22    S must be a string if it starts with fewer than MAXLEN initialized bytes.
  23    If no '\0' terminator is found in that many bytes, return MAXLEN.  */
  24
  25 size_t
  26 strnlen (const char *s, size_t maxlen)
  27 {
  28   /* Do not use memchr, because on some platforms memchr has
  29      undefined behavior if MAXLEN exceeds the number of bytes in S.  */
  30   size_t i;
  31   for (i = 0; i < maxlen && s[i]; i++)
  32     continue;
  33   return i;
  34 }