1/* Case-insensitive searching in a string. 2 Copyright (C) 2005-2014 Free Software Foundation, Inc. 3 Written by Bruno Haible <bruno@clisp.org>, 2005. 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3, or (at your option) 8 any later version. 9 10 This program 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 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program; if not, see <http://www.gnu.org/licenses/>. */ 17 18#include <config.h> 19 20/* Specification. */ 21#include <string.h> 22 23#include <ctype.h> 24#include <stdbool.h> 25#include <strings.h> 26 27#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch)) 28 29/* Two-Way algorithm. */ 30#define RETURN_TYPE char * 31#define AVAILABLE(h, h_l, j, n_l) \ 32 (!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l)) \ 33 && ((h_l) = (j) + (n_l))) 34#define CANON_ELEMENT(c) TOLOWER (c) 35#define CMP_FUNC(p1, p2, l) \ 36 strncasecmp ((const char *) (p1), (const char *) (p2), l) 37#include "str-two-way.h" 38 39/* Find the first occurrence of NEEDLE in HAYSTACK, using 40 case-insensitive comparison. This function gives unspecified 41 results in multibyte locales. */ 42char * 43strcasestr (const char *haystack_start, const char *needle_start) 44{ 45 const char *haystack = haystack_start; 46 const char *needle = needle_start; 47 size_t needle_len; /* Length of NEEDLE. */ 48 size_t haystack_len; /* Known minimum length of HAYSTACK. */ 49 bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */ 50 51 /* Determine length of NEEDLE, and in the process, make sure 52 HAYSTACK is at least as long (no point processing all of a long 53 NEEDLE if HAYSTACK is too short). */ 54 while (*haystack && *needle) 55 { 56 ok &= (TOLOWER ((unsigned char) *haystack) 57 == TOLOWER ((unsigned char) *needle)); 58 haystack++; 59 needle++; 60 } 61 if (*needle) 62 return NULL; 63 if (ok) 64 return (char *) haystack_start; 65 needle_len = needle - needle_start; 66 haystack = haystack_start + 1; 67 haystack_len = needle_len - 1; 68 69 /* Perform the search. Abstract memory is considered to be an array 70 of 'unsigned char' values, not an array of 'char' values. See 71 ISO C 99 section 6.2.6.1. */ 72 if (needle_len < LONG_NEEDLE_THRESHOLD) 73 return two_way_short_needle ((const unsigned char *) haystack, 74 haystack_len, 75 (const unsigned char *) needle_start, 76 needle_len); 77 return two_way_long_needle ((const unsigned char *) haystack, haystack_len, 78 (const unsigned char *) needle_start, 79 needle_len); 80} 81 82#undef LONG_NEEDLE_THRESHOLD 83