Source/WTF/wtf/StringExtras.h

/*
 * Copyright (C) 2006-2017 Apple Inc. All rights reserved.
 * Copyright (C) 2015 Electronic Arts, Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#pragma once

#include <string.h>

#if !HAVE(STRNSTR)

inline char* strnstr(const char* buffer, const char* target, size_t bufferLength)
{
    size_t targetLength = strlen(target);
    if (targetLength == 0)
        return const_cast<char*>(buffer);
    for (const char* start = buffer; *start && start + targetLength <= buffer + bufferLength; start++) {
        if (*start == *target && strncmp(start + 1, target + 1, targetLength - 1) == 0)
            return const_cast<char*>(start);
    }
    return nullptr;
}

#endif

#if !HAVE(MEMMEM)

inline const void* memmem(const void* haystack, size_t haystackLength, const void* needle, size_t needleLength)
{
    const char* pointer = static_cast<const char*>(haystack);
    while (haystackLength >= needleLength) {
        if (!memcmp(pointer, needle, needleLength))
            return pointer;
        pointer++;
        haystackLength--;
    }
    return nullptr;
}

#endif