/* Return the offset of one string within another. Copyright (C) 1994-2019 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 . */ /* This particular implementation was written by Eric Blake, 2008. */ #ifndef _LIBC # include #endif /* Specification of strstr. */ #include #include #ifndef _LIBC # define __builtin_expect(expr, val) (expr) #endif #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 FASTSEARCH(S,C,N) (void*) strchr ((void*)(S), (C)) #include "str-two-way.h" #undef strstr #ifndef STRSTR #define STRSTR strstr #endif /* Return the first occurrence of NEEDLE in HAYSTACK. Return HAYSTACK if NEEDLE is empty, otherwise NULL if NEEDLE is not found in HAYSTACK. */ char * STRSTR (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; /* Skip until we find the first matching char from NEEDLE. */ haystack = strchr (haystack, needle[0]); if (haystack == NULL || needle[1] == '\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; /* Check whether we have a match. This improves performance since we avoid the initialization overhead of the two-way algorithm. */ if (memcmp (haystack, needle, needle_len) == 0) return (char *) haystack; /* 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); } libc_hidden_builtin_def (strstr) #undef LONG_NEEDLE_THRESHOLD