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59 lines
1.9 KiB
C
59 lines
1.9 KiB
C
/* Copyright (C) 1991,92,93,94,96,97,98,2000,2004 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <stddef.h>
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#include <string.h>
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#ifndef _LIBC
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# define __builtin_expect(expr, val) (expr)
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#endif
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#undef memmem
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/* Return the first occurrence of NEEDLE in HAYSTACK. */
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void *
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memmem (haystack, haystack_len, needle, needle_len)
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const void *haystack;
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size_t haystack_len;
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const void *needle;
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size_t needle_len;
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{
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const char *begin;
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const char *const last_possible
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= (const char *) haystack + haystack_len - needle_len;
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if (needle_len == 0)
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/* The first occurrence of the empty string is deemed to occur at
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the beginning of the string. */
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return (void *) haystack;
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/* Sanity check, otherwise the loop might search through the whole
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memory. */
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if (__builtin_expect (haystack_len < needle_len, 0))
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return NULL;
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for (begin = (const char *) haystack; begin <= last_possible; ++begin)
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if (begin[0] == ((const char *) needle)[0] &&
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!memcmp ((const void *) &begin[1],
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(const void *) ((const char *) needle + 1),
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needle_len - 1))
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return (void *) begin;
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return NULL;
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}
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