/* Copyright (C) 1991-2020 Free Software Foundation, Inc. This file is part of the GNU C Library. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ /* @deftypefn Supplemental void* memmem (const void *@var{haystack}, @ size_t @var{haystack_len} const void *@var{needle}, size_t @var{needle_len}) Returns a pointer to the first occurrence of @var{needle} (length @var{needle_len}) in @var{haystack} (length @var{haystack_len}). Returns @code{NULL} if not found. @end deftypefn */ #ifndef _LIBC # include <config.h> #endif #include <stddef.h> #include <string.h> #ifndef _LIBC # define __builtin_expect(expr, val) (expr) #endif #undef memmem /* Return the first occurrence of NEEDLE in HAYSTACK. */ void * memmem (const void *haystack, size_t haystack_len, const void *needle, size_t needle_len) { const char *begin; const char *const last_possible = (const char *) haystack + haystack_len - needle_len; if (needle_len == 0) /* The first occurrence of the empty string is deemed to occur at the beginning of the string. */ return (void *) haystack; /* Sanity check, otherwise the loop might search through the whole memory. */ if (__builtin_expect (haystack_len < needle_len, 0)) return NULL; for (begin = (const char *) haystack; begin <= last_possible; ++begin) if (begin[0] == ((const char *) needle)[0] && !memcmp ((const void *) &begin[1], (const void *) ((const char *) needle + 1), needle_len - 1)) return (void *) begin; return NULL; }