mirror of
https://github.com/mozilla/gecko-dev.git
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355 lines
11 KiB
C++
355 lines
11 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "mozilla/SnappyUncompressInputStream.h"
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#include <algorithm>
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#include "nsIAsyncInputStream.h"
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#include "nsStreamUtils.h"
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#include "snappy/snappy.h"
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namespace mozilla {
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NS_IMPL_ISUPPORTS(SnappyUncompressInputStream,
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nsIInputStream);
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static size_t kCompressedBufferLength =
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detail::SnappyFrameUtils::MaxCompressedBufferLength(snappy::kBlockSize);
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SnappyUncompressInputStream::SnappyUncompressInputStream(nsIInputStream* aBaseStream)
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: mBaseStream(aBaseStream)
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, mUncompressedBytes(0)
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, mNextByte(0)
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, mNextChunkType(Unknown)
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, mNextChunkDataLength(0)
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, mNeedFirstStreamIdentifier(true)
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{
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// This implementation only supports sync base streams. Verify this in debug
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// builds. Note, this is a bit complicated because the streams we support
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// advertise different capabilities:
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// - nsFileInputStream - blocking and sync
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// - nsStringInputStream - non-blocking and sync
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// - nsPipeInputStream - can be blocking, but provides async interface
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#ifdef DEBUG
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bool baseNonBlocking;
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nsresult rv = mBaseStream->IsNonBlocking(&baseNonBlocking);
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MOZ_ASSERT(NS_SUCCEEDED(rv));
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if (baseNonBlocking) {
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nsCOMPtr<nsIAsyncInputStream> async = do_QueryInterface(mBaseStream);
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MOZ_ASSERT(!async);
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}
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#endif
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}
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NS_IMETHODIMP
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SnappyUncompressInputStream::Close()
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{
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if (!mBaseStream) {
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return NS_OK;
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}
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mBaseStream->Close();
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mBaseStream = nullptr;
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mUncompressedBuffer = nullptr;
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mCompressedBuffer = nullptr;
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return NS_OK;
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}
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NS_IMETHODIMP
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SnappyUncompressInputStream::Available(uint64_t* aLengthOut)
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{
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if (!mBaseStream) {
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return NS_BASE_STREAM_CLOSED;
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}
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// If we have uncompressed bytes, then we are done.
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*aLengthOut = UncompressedLength();
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if (*aLengthOut > 0) {
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return NS_OK;
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}
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// Otherwise, attempt to uncompress bytes until we get something or the
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// underlying stream is drained. We loop here because some chunks can
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// be StreamIdentifiers, padding, etc with no data.
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uint32_t bytesRead;
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do {
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nsresult rv = ParseNextChunk(&bytesRead);
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if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
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*aLengthOut = UncompressedLength();
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} while(*aLengthOut == 0 && bytesRead);
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return NS_OK;
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}
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NS_IMETHODIMP
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SnappyUncompressInputStream::Read(char* aBuf, uint32_t aCount,
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uint32_t* aBytesReadOut)
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{
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return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, aBytesReadOut);
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}
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NS_IMETHODIMP
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SnappyUncompressInputStream::ReadSegments(nsWriteSegmentFun aWriter,
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void* aClosure, uint32_t aCount,
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uint32_t* aBytesReadOut)
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{
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*aBytesReadOut = 0;
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if (!mBaseStream) {
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return NS_BASE_STREAM_CLOSED;
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}
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nsresult rv;
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// Do not try to use the base stream's ReadSegements here. Its very
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// unlikely we will get a single buffer that contains all of the compressed
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// data and therefore would have to copy into our own buffer anyways.
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// Instead, focus on making efficient use of the Read() interface.
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while (aCount > 0) {
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// We have some decompressed data in our buffer. Provide it to the
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// callers writer function.
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if (mUncompressedBytes > 0) {
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MOZ_ASSERT(mUncompressedBuffer);
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uint32_t remaining = UncompressedLength();
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uint32_t numToWrite = std::min(aCount, remaining);
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uint32_t numWritten;
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rv = aWriter(this, aClosure, &mUncompressedBuffer[mNextByte], *aBytesReadOut,
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numToWrite, &numWritten);
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// As defined in nsIInputputStream.idl, do not pass writer func errors.
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if (NS_FAILED(rv)) {
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return NS_OK;
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}
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// End-of-file
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if (numWritten == 0) {
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return NS_OK;
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}
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*aBytesReadOut += numWritten;
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mNextByte += numWritten;
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MOZ_ASSERT(mNextByte <= mUncompressedBytes);
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if (mNextByte == mUncompressedBytes) {
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mNextByte = 0;
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mUncompressedBytes = 0;
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}
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aCount -= numWritten;
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continue;
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}
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// Otherwise uncompress the next chunk and loop. Any resulting data
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// will set mUncompressedBytes which we check at the top of the loop.
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uint32_t bytesRead;
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rv = ParseNextChunk(&bytesRead);
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if (NS_FAILED(rv)) { return rv; }
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// If we couldn't read anything and there is no more data to provide
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// to the caller, then this is eof.
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if (bytesRead == 0 && mUncompressedBytes == 0) {
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return NS_OK;
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}
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}
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return NS_OK;
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}
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NS_IMETHODIMP
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SnappyUncompressInputStream::IsNonBlocking(bool* aNonBlockingOut)
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{
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*aNonBlockingOut = false;
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return NS_OK;
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}
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SnappyUncompressInputStream::~SnappyUncompressInputStream()
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{
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Close();
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}
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nsresult
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SnappyUncompressInputStream::ParseNextChunk(uint32_t* aBytesReadOut)
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{
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// There must not be any uncompressed data already in mUncompressedBuffer.
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MOZ_ASSERT(mUncompressedBytes == 0);
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MOZ_ASSERT(mNextByte == 0);
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nsresult rv;
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*aBytesReadOut = 0;
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// Lazily create our two buffers so we can report OOM during stream
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// operation. These allocations only happens once. The buffers are reused
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// until the stream is closed.
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if (!mUncompressedBuffer) {
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mUncompressedBuffer.reset(new (fallible) char[snappy::kBlockSize]);
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if (NS_WARN_IF(!mUncompressedBuffer)) {
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return NS_ERROR_OUT_OF_MEMORY;
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}
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}
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if (!mCompressedBuffer) {
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mCompressedBuffer.reset(new (fallible) char[kCompressedBufferLength]);
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if (NS_WARN_IF(!mCompressedBuffer)) {
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return NS_ERROR_OUT_OF_MEMORY;
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}
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}
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// We have no decompressed data and we also have not seen the start of stream
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// yet. Read and validate the StreamIdentifier chunk. Also read the next
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// header to determine the size of the first real data chunk.
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if (mNeedFirstStreamIdentifier) {
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const uint32_t firstReadLength = kHeaderLength +
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kStreamIdentifierDataLength +
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kHeaderLength;
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MOZ_ASSERT(firstReadLength <= kCompressedBufferLength);
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rv = ReadAll(mCompressedBuffer.get(), firstReadLength, firstReadLength,
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aBytesReadOut);
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if (NS_WARN_IF(NS_FAILED(rv)) || *aBytesReadOut == 0) { return rv; }
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rv = ParseHeader(mCompressedBuffer.get(), kHeaderLength,
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&mNextChunkType, &mNextChunkDataLength);
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if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
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if (NS_WARN_IF(mNextChunkType != StreamIdentifier ||
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mNextChunkDataLength != kStreamIdentifierDataLength)) {
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return NS_ERROR_CORRUPTED_CONTENT;
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}
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size_t offset = kHeaderLength;
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mNeedFirstStreamIdentifier = false;
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size_t numRead;
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size_t numWritten;
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rv = ParseData(mUncompressedBuffer.get(), snappy::kBlockSize, mNextChunkType,
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&mCompressedBuffer[offset],
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mNextChunkDataLength, &numWritten, &numRead);
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if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
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MOZ_ASSERT(numWritten == 0);
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MOZ_ASSERT(numRead == mNextChunkDataLength);
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offset += numRead;
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rv = ParseHeader(&mCompressedBuffer[offset], *aBytesReadOut - offset,
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&mNextChunkType, &mNextChunkDataLength);
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if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
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return NS_OK;
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}
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// We have no compressed data and we don't know how big the next chunk is.
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// This happens when we get an EOF pause in the middle of a stream and also
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// at the end of the stream. Simply read the next header and return. The
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// chunk body will be read on the next entry into this method.
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if (mNextChunkType == Unknown) {
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rv = ReadAll(mCompressedBuffer.get(), kHeaderLength, kHeaderLength,
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aBytesReadOut);
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if (NS_WARN_IF(NS_FAILED(rv)) || *aBytesReadOut == 0) { return rv; }
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rv = ParseHeader(mCompressedBuffer.get(), kHeaderLength,
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&mNextChunkType, &mNextChunkDataLength);
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if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
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return NS_OK;
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}
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// We have no decompressed data, but we do know the size of the next chunk.
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// Read at least that much from the base stream.
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uint32_t readLength = mNextChunkDataLength;
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MOZ_ASSERT(readLength <= kCompressedBufferLength);
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// However, if there is enough data in the base stream, also read the next
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// chunk header. This helps optimize the stream by avoiding many small reads.
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uint64_t avail;
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rv = mBaseStream->Available(&avail);
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if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
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if (avail >= (readLength + kHeaderLength)) {
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readLength += kHeaderLength;
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MOZ_ASSERT(readLength <= kCompressedBufferLength);
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}
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rv = ReadAll(mCompressedBuffer.get(), readLength, mNextChunkDataLength,
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aBytesReadOut);
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if (NS_WARN_IF(NS_FAILED(rv)) || *aBytesReadOut == 0) { return rv; }
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size_t numRead;
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size_t numWritten;
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rv = ParseData(mUncompressedBuffer.get(), snappy::kBlockSize, mNextChunkType,
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mCompressedBuffer.get(), mNextChunkDataLength,
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&numWritten, &numRead);
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if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
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MOZ_ASSERT(numRead == mNextChunkDataLength);
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mUncompressedBytes = numWritten;
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// If we were unable to directly read the next chunk header, then clear
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// our internal state. We will have to perform a small read to get the
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// header the next time we enter this method.
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if (*aBytesReadOut <= mNextChunkDataLength) {
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mNextChunkType = Unknown;
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mNextChunkDataLength = 0;
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return NS_OK;
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}
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// We got the next chunk header. Parse it so that we are ready to for the
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// next call into this method.
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rv = ParseHeader(&mCompressedBuffer[numRead], *aBytesReadOut - numRead,
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&mNextChunkType, &mNextChunkDataLength);
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if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
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return NS_OK;
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}
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nsresult
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SnappyUncompressInputStream::ReadAll(char* aBuf, uint32_t aCount,
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uint32_t aMinValidCount,
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uint32_t* aBytesReadOut)
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{
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MOZ_ASSERT(aCount >= aMinValidCount);
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*aBytesReadOut = 0;
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if (!mBaseStream) {
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return NS_BASE_STREAM_CLOSED;
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}
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uint32_t offset = 0;
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while (aCount > 0) {
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uint32_t bytesRead = 0;
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nsresult rv = mBaseStream->Read(aBuf + offset, aCount, &bytesRead);
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if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
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// EOF, but don't immediately return. We need to validate min read bytes
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// below.
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if (bytesRead == 0) {
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break;
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}
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*aBytesReadOut += bytesRead;
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offset += bytesRead;
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aCount -= bytesRead;
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}
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// Reading zero bytes is not an error. Its the expected EOF condition.
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// Only compare to the minimum valid count if we read at least one byte.
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if (*aBytesReadOut != 0 && *aBytesReadOut < aMinValidCount) {
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return NS_ERROR_CORRUPTED_CONTENT;
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}
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return NS_OK;
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}
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size_t
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SnappyUncompressInputStream::UncompressedLength() const
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{
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MOZ_ASSERT(mNextByte <= mUncompressedBytes);
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return mUncompressedBytes - mNextByte;
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}
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} // namespace mozilla
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