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/*
* Copyright (C) 2022 Apple 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,
* 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.
*/
#include "config.h"
#include "CompressionStreamEncoder.h"
#include "BufferSource.h"
#include "Exception.h"
#include "SharedBuffer.h"
#include <JavaScriptCore/GenericTypedArrayViewInlines.h>
#include <JavaScriptCore/JSCInlines.h>
#include <JavaScriptCore/JSGenericTypedArrayViewInlines.h>
namespace WebCore {
ExceptionOr<RefPtr<Uint8Array>> CompressionStreamEncoder::encode(const BufferSource&& input)
{
auto* data = input.data();
if (!data)
return Exception { TypeError, "No data provided"_s };
auto compressedDataCheck = compress(data, input.length());
if (compressedDataCheck.hasException())
return compressedDataCheck.releaseException();
auto compressedData = compressedDataCheck.returnValue();
if (!compressedData->byteLength())
return nullptr;
return Uint8Array::tryCreate(static_cast<uint8_t *>(compressedData->data()), compressedData->byteLength());
}
ExceptionOr<RefPtr<Uint8Array>> CompressionStreamEncoder::flush()
{
m_didFinish = true;
auto compressedDataCheck = compress(0, 0);
if (compressedDataCheck.hasException())
return compressedDataCheck.releaseException();
auto compressedData = compressedDataCheck.returnValue();
if (!compressedData->byteLength())
return nullptr;
return Uint8Array::tryCreate(static_cast<uint8_t *>(compressedData->data()), compressedData->byteLength());
}
ExceptionOr<bool> CompressionStreamEncoder::initialize()
{
int result = Z_OK;
m_initialized = true;
switch (m_format) {
// Values chosen here are based off
// https://developer.apple.com/documentation/compression/compression_algorithm/compression_zlib?language=objc
case Formats::CompressionFormat::Deflate:
result = deflateInit2(&m_zstream, 5, Z_DEFLATED, -15, 8, Z_DEFAULT_STRATEGY);
break;
case Formats::CompressionFormat::Zlib:
result = deflateInit2(&m_zstream, 5, Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
break;
case Formats::CompressionFormat::Gzip:
result = deflateInit2(&m_zstream, 5, Z_DEFLATED, 15 + 16, 8, Z_DEFAULT_STRATEGY);
break;
default:
RELEASE_ASSERT_NOT_REACHED();
break;
}
if (result != Z_OK)
return Exception { TypeError, "Initialization Failed."_s };
return true;
}
// The compression algorithm is broken up into 2 steps.
// 1. Compression of Data
// 2. Flush Remaining Data
//
// When avail_in is empty we can normally exit performing compression, but during the flush
// step we may have data buffered and will need to continue to keep flushing out the rest.
bool CompressionStreamEncoder::didDeflateFinish(int result) const
{
return !m_zstream.avail_in && (!m_didFinish || (m_didFinish && result == Z_STREAM_END));
}
// See https://www.zlib.net/manual.html#Constants
static bool didDeflateFail(int result)
{
return result != Z_OK && result != Z_STREAM_END && result != Z_BUF_ERROR;
}
ExceptionOr<RefPtr<JSC::ArrayBuffer>> CompressionStreamEncoder::compress(const uint8_t* input, const size_t inputLength)
{
size_t allocateSize = (inputLength < startingAllocationSize) ? startingAllocationSize : inputLength;
auto storage = SharedBufferBuilder();
int result;
bool shouldCompress = true;
m_zstream.next_in = const_cast<z_const Bytef*>(input);
m_zstream.avail_in = inputLength;
if (!m_initialized) {
auto initializeResult = initialize();
if (initializeResult.hasException())
return initializeResult.releaseException();
}
while (shouldCompress) {
auto output = Vector<uint8_t>();
if (!output.tryReserveInitialCapacity(allocateSize)) {
allocateSize /= 4;
if (allocateSize < startingAllocationSize)
return Exception { OutOfMemoryError };
continue;
}
output.resize(allocateSize);
m_zstream.next_out = output.data();
m_zstream.avail_out = output.size();
result = deflate(&m_zstream, m_didFinish ? Z_FINISH : Z_NO_FLUSH);
if (didDeflateFail(result))
return Exception { TypeError, "Failed to compress data."_s };
if (didDeflateFinish(result)) {
shouldCompress = false;
output.resize(allocateSize - m_zstream.avail_out);
}
else {
if (allocateSize < maxAllocationSize)
allocateSize *= 2;
}
storage.append(output);
}
auto compressedData = storage.takeAsArrayBuffer();
if (!compressedData)
return Exception { OutOfMemoryError };
return compressedData;
}
} // namespace WebCore
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