/* c-strcasestr.c -- case insensitive substring search in C locale Copyright (C) 2005-2024 Free Software Foundation, Inc. Written by Bruno Haible , 2005. This file is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This file is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see . */ #include /* Specification. */ #include "c-strcasestr.h" #include #include "c-ctype.h" #include "c-strcase.h" /* Two-Way algorithm. */ #define RETURN_TYPE char * #define AVAILABLE(h, h_l, j, n_l) \ (!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l)) \ && ((h_l) = (j) + (n_l))) #define CANON_ELEMENT c_tolower #define CMP_FUNC(p1, p2, l) \ c_strncasecmp ((const char *) (p1), (const char *) (p2), l) #include "str-two-way.h" /* Find the first occurrence of NEEDLE in HAYSTACK, using case-insensitive comparison from the C locale, regardless of the current locale. */ char * c_strcasestr (const char *haystack_start, const char *needle_start) { const char *haystack = haystack_start; const char *needle = needle_start; size_t needle_len; /* Length of NEEDLE. */ size_t haystack_len; /* Known minimum length of HAYSTACK. */ bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */ /* Determine length of NEEDLE, and in the process, make sure HAYSTACK is at least as long (no point processing all of a long NEEDLE if HAYSTACK is too short). */ while (*haystack && *needle) ok &= (c_tolower ((unsigned char) *haystack++) == c_tolower ((unsigned char) *needle++)); if (*needle) return NULL; if (ok) return (char *) haystack_start; needle_len = needle - needle_start; haystack = haystack_start + 1; haystack_len = needle_len - 1; /* Perform the search. Abstract memory is considered to be an array of 'unsigned char' values, not an array of 'char' values. See ISO C 99 section 6.2.6.1. */ if (needle_len < LONG_NEEDLE_THRESHOLD) return two_way_short_needle ((const unsigned char *) haystack, haystack_len, (const unsigned char *) needle_start, needle_len); return two_way_long_needle ((const unsigned char *) haystack, haystack_len, (const unsigned char *) needle_start, needle_len); } #undef LONG_NEEDLE_THRESHOLD