47026978bf
This fixes calls like memmem("hello", 5, "lo", 2);
Also zero-length needle is deemed to exist at beginning of haystack.
This behavior matches memmem() on Linux, FreeBSD, NetBSD and OpenBSD.
Signed-off-by: Juha Niskanen <juha.niskanen@haltian.com>
78 lines
2.5 KiB
C
78 lines
2.5 KiB
C
/****************************************************************************
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* libs/libc/string/lib_memmem.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <string.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: memmem
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*
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* Description:
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* The memmem() function finds the start of the first occurrence of the
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* substring needle of length needlelen in the memory area haystack of
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* length haystacklen.
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*
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* Returned Value:
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* The memmem() function returns a pointer to the beginning of the
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* substring, or NULL if the substring is not found.
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*
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****************************************************************************/
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#undef memmem /* See mm/README.txt */
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FAR void *memmem(FAR const void *haystack, size_t haystacklen,
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FAR const void *needle, size_t needlelen)
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{
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FAR const unsigned char *h = haystack;
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FAR const unsigned char *n = needle;
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size_t i;
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size_t y;
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if (needlelen == 0)
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{
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return (void *)haystack;
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}
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if (needlelen > haystacklen)
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{
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return NULL;
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}
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for (i = 0; i <= haystacklen - needlelen; i++)
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{
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y = 0;
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while (h[i + y] == n[y])
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{
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if (++y == needlelen)
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{
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return (void *)(h + i);
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}
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}
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}
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return NULL;
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}
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