mirror of
https://github.com/darlinghq/darling-JavaScriptCore.git
synced 2024-11-23 04:09:40 +00:00
100 lines
3.8 KiB
C++
100 lines
3.8 KiB
C++
/*
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* Copyright (C) 2012-2020 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include "CodeBlockHash.h"
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#include "SourceCode.h"
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#include <wtf/SHA1.h>
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#include <wtf/SixCharacterHash.h>
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namespace JSC {
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CodeBlockHash::CodeBlockHash(const char* string)
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: m_hash(sixCharacterHashStringToInteger(string))
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{
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}
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CodeBlockHash::CodeBlockHash(const SourceCode& sourceCode, CodeSpecializationKind kind)
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: m_hash(0)
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{
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SHA1 sha1;
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// The maxSourceCodeLengthToHash is a heuristic to avoid crashing fuzzers
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// due to resource exhaustion. This is OK to do because:
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// 1. CodeBlockHash is not a critical hash.
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// 2. In practice, reasonable source code are not 500 MB or more long.
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// 3. And if they are that long, then we are still diversifying the hash on
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// their length. But if they do collide, it's OK.
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// The only invariant here is that we should always produce the same hash
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// for the same source string. The algorithm below achieves that.
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ASSERT(sourceCode.length() >= 0);
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constexpr unsigned maxSourceCodeLengthToHash = 500 * MB;
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if (static_cast<unsigned>(sourceCode.length()) < maxSourceCodeLengthToHash)
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sha1.addBytes(sourceCode.toUTF8());
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else {
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// Just hash with the length and samples of the source string instead.
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StringView str = sourceCode.provider()->source();
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unsigned index = 0;
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unsigned oldIndex = 0;
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unsigned length = str.length();
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unsigned step = (length >> 10) + 1;
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sha1.addBytes(bitwise_cast<uint8_t*>(&length), sizeof(length));
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do {
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UChar character = str[index];
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sha1.addBytes(bitwise_cast<uint8_t*>(&character), sizeof(character));
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oldIndex = index;
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index += step;
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} while (index > oldIndex && index < length);
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}
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SHA1::Digest digest;
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sha1.computeHash(digest);
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m_hash = digest[0] | (digest[1] << 8) | (digest[2] << 16) | (digest[3] << 24);
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if (m_hash == 0 || m_hash == 1)
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m_hash += 0x2d5a93d0; // Ensures a non-zero hash, and gets us #Azero0 for CodeForCall and #Azero1 for CodeForConstruct.
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static_assert(static_cast<unsigned>(CodeForCall) == 0, "");
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static_assert(static_cast<unsigned>(CodeForConstruct) == 1, "");
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m_hash ^= static_cast<unsigned>(kind);
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ASSERT(m_hash);
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}
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void CodeBlockHash::dump(PrintStream& out) const
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{
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std::array<char, 7> buffer = integerToSixCharacterHashString(m_hash);
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#if ASSERT_ENABLED
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CodeBlockHash recompute(buffer.data());
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ASSERT(recompute == *this);
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#endif // ASSERT_ENABLED
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out.print(buffer.data());
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}
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} // namespace JSC
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