| /* Copyright (C) 1991-2019 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; |
| } |