1 /* c-strcasestr.c -- case insensitive substring search in C locale 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 of the License, or ~bb8 (at your option) 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 "c-strcasestr.h" 22 23 #include <stdbool.h> 24 #include <string.h> 25 26 #include "c-ctype.h" 27 #include "c-strcase.h" 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 35 #define CMP_FUNC(p1, p2, l) \ 36 c_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 case-insensitive 40 comparison from the C locale, regardless of the current locale. */ 41 char * 42 c_strcasestr (const char *haystack_start, const char *needle_start) 43 { 44 const char *haystack = haystack_start; 45 const char *needle = needle_start; 46 size_t needle_len; /* Length of NEEDLE. */ 47 size_t haystack_len; /* Known minimum length of HAYSTACK. */ 48 bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */ 49 50 /* Determine length of NEEDLE, and in the process, make sure 51 HAYSTACK is at least as long (no point processing all of a long 52 NEEDLE if HAYSTACK is too short). */ 53 while (*haystack && *needle) 54 ok &= (c_tolower ((unsigned char) *haystack++) 55 == c_tolower ((unsigned char) *needle++)); 56 if (*needle) 57 return NULL; 58 if (ok) 59 return (char *) haystack_start; 60 needle_len = needle - needle_start; 61 haystack = haystack_start + 1; 62 haystack_len = needle_len - 1; 63 64 /* Perform the search. Abstract memory is considered to be an array 65 of 'unsigned char' values, not an array of 'char' values. See 66 ISO C 99 section 6.2.6.1. */ 67 if (needle_len < LONG_NEEDLE_THRESHOLD) 68 return two_way_short_needle ((const unsigned char *) haystack, 69 haystack_len, 70 (const unsigned char *) needle_start, 71 needle_len); 72 return two_way_long_needle ((const unsigned char *) haystack, haystack_len, 73 (const unsigned char *) needle_start, 74 needle_len); 75 } 76 77 #undef LONG_NEEDLE_THRESHOLD 78