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-rw-r--r--libc/string/generic/memmem.c50
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diff --git a/libc/string/generic/memmem.c b/libc/string/generic/memmem.c
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+/* Copyright (C) 1991,92,93,94,96,97,98,2000 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <string.h>
+#include <stddef.h>
+
+#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;
+}