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