1 // SPDX-License-Identifier: BSD-3-Clause 2 /* 3 * Copyright (c) 1994-2009 Red Hat, Inc. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions are met: 8 * 9 * 1. Redistributions of source code must retain the above copyright notice, 10 * this list of conditions and the following disclaimer. 11 * 12 * 2. Redistributions in binary form must reproduce the above copyright notice, 13 * this list of conditions and the following disclaimer in the documentation 14 * and/or other materials provided with the distribution. 15 * 16 * 3. Neither the name of the copyright holder nor the names of its 17 * contributors may be used to endorse or promote products derived from this 18 * software without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 21 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 FUNCTION 35 <<strnlen>>---character string length 36 37 INDEX 38 strnlen 39 40 ANSI_SYNOPSIS 41 #include <string.h> 42 size_t strnlen(const char *<[str]>, size_t <[n]>); 43 44 TRAD_SYNOPSIS 45 #include <string.h> 46 size_t strnlen(<[str]>, <[n]>) 47 char *<[src]>; 48 size_t <[n]>; 49 50 DESCRIPTION 51 The <<strnlen>> function works out the length of the string 52 starting at <<*<[str]>>> by counting chararacters until it 53 reaches a NUL character or the maximum: <[n]> number of 54 characters have been inspected. 55 56 RETURNS 57 <<strnlen>> returns the character count or <[n]>. 58 59 PORTABILITY 60 <<strnlen>> is a GNU extension. 61 62 <<strnlen>> requires no supporting OS subroutines. 63 64 */ 65 66 #undef __STRICT_ANSI__ 67 #include "_ansi.h" 68 #include <string.h> 69 70 size_t 71 _DEFUN (strnlen, (str, n), 72 _CONST char *str _AND 73 size_t n) 74 { 75 _CONST char *start = str; 76 77 while (n-- > 0 && *str) 78 str++; 79 80 return str - start; 81 } 82