/* Return the offset of one string within another. Copyright (C) 1994-2024 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library 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. The GNU C Library 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 the GNU C Library; if not, see . */ /* * My personal strstr() implementation that beats most other algorithms. * Until someone tells me otherwise, I assume that this is the * fastest implementation of strstr() in C. * I deliberately chose not to comment it. You should have at least * as much fun trying to understand it, as I had to write it :-). * * Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de */ /* Specification. */ #include #include #include #include #define TOLOWER(Ch) tolower (Ch) /* Two-Way algorithm. */ #define RETURN_TYPE char * #define AVAILABLE(h, h_l, j, n_l) \ (((j) + (n_l) <= (h_l)) \ || ((h_l) += __strnlen ((void*)((h) + (h_l)), (n_l) + 512), \ (j) + (n_l) <= (h_l))) #define CHECK_EOL (1) #define RET0_IF_0(a) if (!a) goto ret0 #define CANON_ELEMENT(c) TOLOWER (c) #define CMP_FUNC(p1, p2, l) \ __strncasecmp ((const char *) (p1), (const char *) (p2), l) #include "str-two-way.h" #undef strcasestr #undef __strcasestr #ifndef STRCASESTR #define STRCASESTR __strcasestr #endif /* Find the first occurrence of NEEDLE in HAYSTACK, using case-insensitive comparison. This function gives unspecified results in multibyte locales. */ char * STRCASESTR (const char *haystack, const char *needle) { size_t needle_len; /* Length of NEEDLE. */ size_t haystack_len; /* Known minimum length of HAYSTACK. */ /* Handle empty NEEDLE special case. */ if (needle[0] == '\0') return (char *) haystack; /* Ensure HAYSTACK length is at least as long as NEEDLE length. Since a match may occur early on in a huge HAYSTACK, use strnlen and read ahead a few cachelines for improved performance. */ needle_len = strlen (needle); haystack_len = __strnlen (haystack, needle_len + 256); if (haystack_len < needle_len) return NULL; /* 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, needle_len); return two_way_long_needle ((const unsigned char *) haystack, haystack_len, (const unsigned char *) needle, needle_len); } #undef LONG_NEEDLE_THRESHOLD #ifndef NO_ALIAS weak_alias (__strcasestr, strcasestr) #endif