private static void CopyUncompressedData(BrotliState state)
{
BitReader br = state.br;
byte[] ringBuffer = state.ringBuffer;
// Could happen if block ends at ring buffer end.
if (state.metaBlockLength <= 0)
{
BitReader.Reload(br);
state.runningState = RunningState.BlockStart;
return;
}
int chunkLength = Math.Min(state.ringBufferSize - state.pos, state.metaBlockLength);
BitReader.CopyBytes(br, ringBuffer, state.pos, chunkLength);
state.metaBlockLength -= chunkLength;
state.pos += chunkLength;
if (state.pos == state.ringBufferSize)
{
state.nextRunningState = RunningState.CopyUncompressed;
state.bytesToWrite = state.ringBufferSize;
state.bytesWritten = 0;
state.runningState = RunningState.Write;
return;
}
BitReader.Reload(br);
state.runningState = RunningState.BlockStart;
}
/// <summary>
/// Creates a <see cref="Stream"/> wrapper that decompresses brotli data.
/// <para> For byte-by-byte reading (<see cref="ReadByte()"/>) internal buffer of specified size is
/// allocated and used.</para>
/// <para> Will block the thread until first kilobyte of data of source is available.</para>
/// </summary>
/// <param name="source">compressed data source</param>
/// <param name="byteReadBufferSize">size of internal buffer used in case of byte-by-byte reading</param>
/// <param name="customDictionary">custom dictionary data; <see langword="null"/> if not used</param>
/// <exception cref="IOException">in case of corrupted data or source stream problems</exception>
public BrotliInputStream(Stream source, int byteReadBufferSize, byte[] customDictionary)
{
if (byteReadBufferSize <= 0)
{
throw new ArgumentException("Bad buffer size:" + byteReadBufferSize);
}
else if (source == null)
{
throw new ArgumentException("source is null");
}
_buffer = new byte[byteReadBufferSize];
_remainingBufferBytes = 0;
_bufferOffset = 0;
try
{
BrotliState.SetInput(_state, source);
}
catch (BrotliRuntimeException ex)
{
throw new IOException("Brotli decoder initialization failed", ex);
}
if (customDictionary != null && customDictionary.Length != 0)
{
BrotliDecode.SetCustomDictionary(_state, customDictionary);
}
}
private static void DecodeBlockTypeAndLength(BrotliState state, int treeType)
{
BitReader br = state.br;
int[] ringBuffers = state.blockTypeRb;
int offset = treeType * 2;
BitReader.FillBitWindow(br);
int blockType = ReadSymbol(state.blockTypeTrees, treeType * Huffman.HuffmanMaxTableSize, br);
state.blockLength[treeType] = ReadBlockLength(state.blockLenTrees, treeType * Huffman.HuffmanMaxTableSize, br);
if (blockType == 1)
{
blockType = ringBuffers[offset + 1] + 1;
}
else if (blockType == 0)
{
blockType = ringBuffers[offset];
}
else
{
blockType -= 2;
}
if (blockType >= state.numBlockTypes[treeType])
{
blockType -= state.numBlockTypes[treeType];
}
ringBuffers[offset] = ringBuffers[offset + 1];
ringBuffers[offset + 1] = blockType;
}
private static void DecodeMetaBlockLength(BitReader br, BrotliState state)
{
state.inputEnd = BitReader.ReadBits(br, 1) == 1;
state.metaBlockLength = 0;
state.isUncompressed = false;
state.isMetadata = false;
if (state.inputEnd && BitReader.ReadBits(br, 1) != 0)
{
return;
}
int sizeNibbles = BitReader.ReadBits(br, 2) + 4;
if (sizeNibbles == 7)
{
state.isMetadata = true;
if (BitReader.ReadBits(br, 1) != 0)
{
throw new BrotliRuntimeException("Corrupted reserved bit");
}
int sizeBytes = BitReader.ReadBits(br, 2);
if (sizeBytes == 0)
{
return;
}
for (int i = 0; i < sizeBytes; i++)
{
int bits = BitReader.ReadBits(br, 8);
if (bits == 0 && i + 1 == sizeBytes && sizeBytes > 1)
{
throw new BrotliRuntimeException("Exuberant nibble");
}
state.metaBlockLength |= bits << (i * 8);
}
}
else
{
for (int i = 0; i < sizeNibbles; i++)
{
int bits = BitReader.ReadBits(br, 4);
if (bits == 0 && i + 1 == sizeNibbles && sizeNibbles > 4)
{
throw new BrotliRuntimeException("Exuberant nibble");
}
state.metaBlockLength |= bits << (i * 4);
}
}
state.metaBlockLength++;
if (!state.inputEnd)
{
state.isUncompressed = BitReader.ReadBits(br, 1) == 1;
}
}
private static void DecodeLiteralBlockSwitch(BrotliState state)
{
DecodeBlockTypeAndLength(state, 0);
int literalBlockType = state.blockTypeRb[1];
state.contextMapSlice = literalBlockType << LiteralContextBits;
state.literalTreeIndex = state.contextMap[state.contextMapSlice] & unchecked ((int)(0xFF));
state.literalTree = state.hGroup0.trees[state.literalTreeIndex];
int contextMode = state.contextModes[literalBlockType];
state.contextLookupOffset1 = Context.LookupOffsets[contextMode];
state.contextLookupOffset2 = Context.LookupOffsets[contextMode + 1];
}
/// <exception cref="IOException"/>
internal static void Close(BrotliState state)
{
if (state.runningState == RunningState.Uninitialized)
{
throw new InvalidOperationException("State MUST be initialized");
}
if (state.runningState == RunningState.Closed)
{
return;
}
state.runningState = RunningState.Closed;
BitReader.Close(state.br);
}
private static void MaybeReallocateRingBuffer(BrotliState state)
{
int newSize = state.maxRingBufferSize;
if ((long)newSize > state.expectedTotalSize)
{
/* TODO: Handle 2GB+ cases more gracefully. */
int minimalNewSize = (int)state.expectedTotalSize + state.customDictionary.Length;
while ((newSize >> 1) > minimalNewSize)
{
newSize >>= 1;
}
if (!state.inputEnd && newSize < 16384 && state.maxRingBufferSize >= 16384)
{
newSize = 16384;
}
}
if (newSize <= state.ringBufferSize)
{
return;
}
int ringBufferSizeWithSlack = newSize + Dictionary.MaxTransformedWordLength;
byte[] newBuffer = new byte[ringBufferSizeWithSlack];
if (state.ringBuffer != null)
{
Array.Copy(state.ringBuffer, 0, newBuffer, 0, state.ringBufferSize);
}
else if (state.customDictionary.Length != 0)
{
/* Prepend custom dictionary, if any. */
int length = state.customDictionary.Length;
int offset = 0;
if (length > state.maxBackwardDistance)
{
offset = length - state.maxBackwardDistance;
length = state.maxBackwardDistance;
}
Array.Copy(state.customDictionary, offset, newBuffer, 0, length);
state.pos = length;
state.bytesToIgnore = length;
}
state.ringBuffer = newBuffer;
state.ringBufferSize = newSize;
}
private static bool WriteRingBuffer(BrotliState state)
{
/* Ignore custom dictionary bytes. */
if (state.bytesToIgnore != 0)
{
state.bytesWritten += state.bytesToIgnore;
state.bytesToIgnore = 0;
}
int toWrite = Math.Min(state.outputLength - state.outputUsed, state.bytesToWrite - state.bytesWritten);
if (toWrite != 0)
{
Array.Copy(state.ringBuffer, state.bytesWritten, state.output, state.outputOffset + state.outputUsed, toWrite);
state.outputUsed += toWrite;
state.bytesWritten += toWrite;
}
return(state.outputUsed < state.outputLength);
}
/// <summary>Associate input with decoder state.</summary>
/// <param name="state">uninitialized state without associated input</param>
/// <param name="input">compressed data source</param>
internal static void SetInput(BrotliState state, Stream input)
{
if (state.runningState != RunningState.Uninitialized)
{
throw new InvalidOperationException("State MUST be uninitialized");
}
BitReader.Init(state.br, input);
int windowBits = DecodeWindowBits(state.br);
if (windowBits == 9)
{
/* Reserved case for future expansion. */
throw new BrotliRuntimeException("Invalid 'windowBits' code");
}
state.maxRingBufferSize = 1 << windowBits;
state.maxBackwardDistance = state.maxRingBufferSize - 16;
state.runningState = RunningState.BlockStart;
}
/// <summary>Reads next metablock header.</summary>
/// <param name="state">decoding state</param>
private static void ReadMetablockInfo(BrotliState state)
{
BitReader br = state.br;
if (state.inputEnd)
{
state.nextRunningState = RunningState.Finished;
state.bytesToWrite = state.pos;
state.bytesWritten = 0;
state.runningState = RunningState.Write;
return;
}
// TODO: Reset? Do we need this?
state.hGroup0.codes = null;
state.hGroup0.trees = null;
state.hGroup1.codes = null;
state.hGroup1.trees = null;
state.hGroup2.codes = null;
state.hGroup2.trees = null;
BitReader.ReadMoreInput(br);
DecodeMetaBlockLength(br, state);
if (state.metaBlockLength == 0 && !state.isMetadata)
{
return;
}
if (state.isUncompressed || state.isMetadata)
{
BitReader.JumpToByteBoundary(br);
state.runningState = state.isMetadata ? RunningState.ReadMetadata : RunningState.CopyUncompressed;
}
else
{
state.runningState = RunningState.CompressedBlockStart;
}
if (state.isMetadata)
{
return;
}
state.expectedTotalSize += state.metaBlockLength;
if (state.ringBufferSize < state.maxRingBufferSize)
{
MaybeReallocateRingBuffer(state);
}
}
/// <summary><inheritDoc/></summary>
/// <exception cref="IOException"/>
public override void Close()
{
BrotliState.Close(_state);
}
/// <summary>Actual decompress implementation.</summary>
internal static void Decompress(BrotliState state)
{
if (state.runningState == RunningState.Uninitialized)
{
throw new InvalidOperationException("Can't decompress until initialized");
}
if (state.runningState == RunningState.Closed)
{
throw new InvalidOperationException("Can't decompress after close");
}
BitReader br = state.br;
int ringBufferMask = state.ringBufferSize - 1;
byte[] ringBuffer = state.ringBuffer;
while (state.runningState != RunningState.Finished)
{
switch (state.runningState)
{
case RunningState.BlockStart:
{
// TODO: extract cases to methods for the better readability.
if (state.metaBlockLength < 0)
{
throw new BrotliRuntimeException("Invalid metablock length");
}
ReadMetablockInfo(state);
/* Ring-buffer would be reallocated here. */
ringBufferMask = state.ringBufferSize - 1;
ringBuffer = state.ringBuffer;
continue;
}
case RunningState.CompressedBlockStart:
{
ReadMetablockHuffmanCodesAndContextMaps(state);
state.runningState = RunningState.MainLoop;
goto case RunningState.MainLoop;
}
case RunningState.MainLoop:
{
// Fall through
if (state.metaBlockLength <= 0)
{
state.runningState = RunningState.BlockStart;
continue;
}
BitReader.ReadMoreInput(br);
if (state.blockLength[1] == 0)
{
DecodeCommandBlockSwitch(state);
}
state.blockLength[1]--;
BitReader.FillBitWindow(br);
int cmdCode = ReadSymbol(state.hGroup1.codes, state.treeCommandOffset, br);
int rangeIdx = (int)(((uint)cmdCode) >> 6);
state.distanceCode = 0;
if (rangeIdx >= 2)
{
rangeIdx -= 2;
state.distanceCode = -1;
}
int insertCode = Prefix.InsertRangeLut[rangeIdx] + (((int)(((uint)cmdCode) >> 3)) & 7);
int copyCode = Prefix.CopyRangeLut[rangeIdx] + (cmdCode & 7);
state.insertLength = Prefix.InsertLengthOffset[insertCode] + BitReader.ReadBits(br, Prefix.InsertLengthNBits[insertCode]);
state.copyLength = Prefix.CopyLengthOffset[copyCode] + BitReader.ReadBits(br, Prefix.CopyLengthNBits[copyCode]);
state.j = 0;
state.runningState = RunningState.InsertLoop;
goto case RunningState.InsertLoop;
}
case RunningState.InsertLoop:
{
// Fall through
if (state.trivialLiteralContext)
{
while (state.j < state.insertLength)
{
BitReader.ReadMoreInput(br);
if (state.blockLength[0] == 0)
{
DecodeLiteralBlockSwitch(state);
}
state.blockLength[0]--;
BitReader.FillBitWindow(br);
ringBuffer[state.pos] = unchecked ((byte)ReadSymbol(state.hGroup0.codes, state.literalTree, br));
state.j++;
if (state.pos++ == ringBufferMask)
{
state.nextRunningState = RunningState.InsertLoop;
state.bytesToWrite = state.ringBufferSize;
state.bytesWritten = 0;
state.runningState = RunningState.Write;
break;
}
}
}
else
{
int prevByte1 = ringBuffer[(state.pos - 1) & ringBufferMask] & unchecked ((int)(0xFF));
int prevByte2 = ringBuffer[(state.pos - 2) & ringBufferMask] & unchecked ((int)(0xFF));
while (state.j < state.insertLength)
{
BitReader.ReadMoreInput(br);
if (state.blockLength[0] == 0)
{
DecodeLiteralBlockSwitch(state);
}
int literalTreeIndex = state.contextMap[state.contextMapSlice + (Context.Lookup[state.contextLookupOffset1 + prevByte1] | Context.Lookup[state.contextLookupOffset2 + prevByte2])] & unchecked ((int)(0xFF));
state.blockLength[0]--;
prevByte2 = prevByte1;
BitReader.FillBitWindow(br);
prevByte1 = ReadSymbol(state.hGroup0.codes, state.hGroup0.trees[literalTreeIndex], br);
ringBuffer[state.pos] = unchecked ((byte)prevByte1);
state.j++;
if (state.pos++ == ringBufferMask)
{
state.nextRunningState = RunningState.InsertLoop;
state.bytesToWrite = state.ringBufferSize;
state.bytesWritten = 0;
state.runningState = RunningState.Write;
break;
}
}
}
if (state.runningState != RunningState.InsertLoop)
{
continue;
}
state.metaBlockLength -= state.insertLength;
if (state.metaBlockLength <= 0)
{
state.runningState = RunningState.MainLoop;
continue;
}
if (state.distanceCode < 0)
{
BitReader.ReadMoreInput(br);
if (state.blockLength[2] == 0)
{
DecodeDistanceBlockSwitch(state);
}
state.blockLength[2]--;
BitReader.FillBitWindow(br);
state.distanceCode = ReadSymbol(state.hGroup2.codes,
state.hGroup2.trees[state.distContextMap[state.distContextMapSlice + (state.copyLength > 4 ? 3 : state.copyLength - 2)] & unchecked ((int)(0xFF))], br);
if (state.distanceCode >= state.numDirectDistanceCodes)
{
state.distanceCode -= state.numDirectDistanceCodes;
int postfix = state.distanceCode & state.distancePostfixMask;
state.distanceCode = (int)(((uint)state.distanceCode) >> state.distancePostfixBits);
int n = ((int)(((uint)state.distanceCode) >> 1)) + 1;
int offset = ((2 + (state.distanceCode & 1)) << n) - 4;
state.distanceCode = state.numDirectDistanceCodes + postfix + ((offset + BitReader.ReadBits(br, n)) << state.distancePostfixBits);
}
}
// Convert the distance code to the actual distance by possibly looking up past distances
// from the ringBuffer.
state.distance = TranslateShortCodes(state.distanceCode, state.distRb, state.distRbIdx);
if (state.distance < 0)
{
throw new BrotliRuntimeException("Negative distance");
}
// COV_NF_LINE
if (state.maxDistance != state.maxBackwardDistance && state.pos < state.maxBackwardDistance)
{
state.maxDistance = state.pos;
}
else
{
state.maxDistance = state.maxBackwardDistance;
}
state.copyDst = state.pos;
if (state.distance > state.maxDistance)
{
state.runningState = RunningState.Transform;
continue;
}
if (state.distanceCode > 0)
{
state.distRb[state.distRbIdx & 3] = state.distance;
state.distRbIdx++;
}
if (state.copyLength > state.metaBlockLength)
{
throw new BrotliRuntimeException("Invalid backward reference");
}
// COV_NF_LINE
state.j = 0;
state.runningState = RunningState.CopyLoop;
goto case RunningState.CopyLoop;
}
case RunningState.CopyLoop:
{
// fall through
int src = (state.pos - state.distance) & ringBufferMask;
int dst = state.pos;
int copyLength = state.copyLength - state.j;
if ((src + copyLength < ringBufferMask) && (dst + copyLength < ringBufferMask))
{
for (int k = 0; k < copyLength; ++k)
{
ringBuffer[dst++] = ringBuffer[src++];
}
state.j += copyLength;
state.metaBlockLength -= copyLength;
state.pos += copyLength;
}
else
{
for (; state.j < state.copyLength;)
{
ringBuffer[state.pos] = ringBuffer[(state.pos - state.distance) & ringBufferMask];
state.metaBlockLength--;
state.j++;
if (state.pos++ == ringBufferMask)
{
state.nextRunningState = RunningState.CopyLoop;
state.bytesToWrite = state.ringBufferSize;
state.bytesWritten = 0;
state.runningState = RunningState.Write;
break;
}
}
}
if (state.runningState == RunningState.CopyLoop)
{
state.runningState = RunningState.MainLoop;
}
continue;
}
case RunningState.Transform:
{
if (state.copyLength >= Dictionary.MinWordLength && state.copyLength <= Dictionary.MaxWordLength)
{
int offset = Dictionary.OffsetsByLength[state.copyLength];
int wordId = state.distance - state.maxDistance - 1;
int shift = Dictionary.SizeBitsByLength[state.copyLength];
int mask = (1 << shift) - 1;
int wordIdx = wordId & mask;
int transformIdx = (int)(((uint)wordId) >> shift);
offset += wordIdx * state.copyLength;
if (transformIdx < BrotliTransform.Transforms.Length)
{
int len = BrotliTransform.TransformDictionaryWord(ringBuffer, state.copyDst,
Dictionary.GetData(), offset, state.copyLength, BrotliTransform.Transforms[transformIdx]);
state.copyDst += len;
state.pos += len;
state.metaBlockLength -= len;
if (state.copyDst >= state.ringBufferSize)
{
state.nextRunningState = RunningState.CopyWrapBuffer;
state.bytesToWrite = state.ringBufferSize;
state.bytesWritten = 0;
state.runningState = RunningState.Write;
continue;
}
}
else
{
throw new BrotliRuntimeException("Invalid backward reference");
}
}
else
{
// COV_NF_LINE
throw new BrotliRuntimeException("Invalid backward reference");
}
// COV_NF_LINE
state.runningState = RunningState.MainLoop;
continue;
}
case RunningState.CopyWrapBuffer:
{
Array.Copy(ringBuffer, state.ringBufferSize, ringBuffer, 0,
state.copyDst - state.ringBufferSize);
state.runningState = RunningState.MainLoop;
continue;
}
case RunningState.ReadMetadata:
{
while (state.metaBlockLength > 0)
{
BitReader.ReadMoreInput(br);
// Optimize
BitReader.ReadBits(br, 8);
state.metaBlockLength--;
}
state.runningState = RunningState.BlockStart;
continue;
}
case RunningState.CopyUncompressed:
{
CopyUncompressedData(state);
continue;
}
case RunningState.Write:
{
if (!WriteRingBuffer(state))
{
// Output buffer is full.
return;
}
if (state.pos >= state.maxBackwardDistance)
{
state.maxDistance = state.maxBackwardDistance;
}
state.pos &= ringBufferMask;
state.runningState = state.nextRunningState;
continue;
}
default:
{
throw new BrotliRuntimeException("Unexpected state " + state.runningState);
}
}
}
if (state.runningState == RunningState.Finished)
{
if (state.metaBlockLength < 0)
{
throw new BrotliRuntimeException("Invalid metablock length");
}
BitReader.JumpToByteBoundary(br);
BitReader.CheckHealth(state.br, true);
}
}
internal static void SetCustomDictionary(BrotliState state, byte[] data)
{
state.customDictionary = (data == null) ? new byte[0] : data;
}
private static void ReadMetablockHuffmanCodesAndContextMaps(BrotliState state)
{
BitReader br = state.br;
for (int i = 0; i < 3; i++)
{
state.numBlockTypes[i] = DecodeVarLenUnsignedByte(br) + 1;
state.blockLength[i] = 1 << 28;
if (state.numBlockTypes[i] > 1)
{
ReadHuffmanCode(state.numBlockTypes[i] + 2, state.blockTypeTrees, i * Huffman.HuffmanMaxTableSize, br);
ReadHuffmanCode(NumBlockLengthCodes, state.blockLenTrees, i * Huffman.HuffmanMaxTableSize, br);
state.blockLength[i] = ReadBlockLength(state.blockLenTrees, i * Huffman.HuffmanMaxTableSize, br);
}
}
BitReader.ReadMoreInput(br);
state.distancePostfixBits = BitReader.ReadBits(br, 2);
state.numDirectDistanceCodes = NumDistanceShortCodes + (BitReader.ReadBits(br, 4) << state.distancePostfixBits);
state.distancePostfixMask = (1 << state.distancePostfixBits) - 1;
int numDistanceCodes = state.numDirectDistanceCodes + (48 << state.distancePostfixBits);
// TODO: Reuse?
state.contextModes = new byte[state.numBlockTypes[0]];
for (int i = 0; i < state.numBlockTypes[0];)
{
/* Ensure that less than 256 bits read between readMoreInput. */
int limit = Math.Min(i + 96, state.numBlockTypes[0]);
for (; i < limit; ++i)
{
state.contextModes[i] = unchecked ((byte)(BitReader.ReadBits(br, 2) << 1));
}
BitReader.ReadMoreInput(br);
}
// TODO: Reuse?
state.contextMap = new byte[state.numBlockTypes[0] << LiteralContextBits];
int numLiteralTrees = DecodeContextMap(state.numBlockTypes[0] << LiteralContextBits, state.contextMap, br);
state.trivialLiteralContext = true;
for (int j = 0; j < state.numBlockTypes[0] << LiteralContextBits; j++)
{
if (state.contextMap[j] != j >> LiteralContextBits)
{
state.trivialLiteralContext = false;
break;
}
}
// TODO: Reuse?
state.distContextMap = new byte[state.numBlockTypes[2] << DistanceContextBits];
int numDistTrees = DecodeContextMap(state.numBlockTypes[2] << DistanceContextBits, state.distContextMap, br);
HuffmanTreeGroup.Init(state.hGroup0, NumLiteralCodes, numLiteralTrees);
HuffmanTreeGroup.Init(state.hGroup1, NumInsertAndCopyCodes, state.numBlockTypes[1]);
HuffmanTreeGroup.Init(state.hGroup2, numDistanceCodes, numDistTrees);
HuffmanTreeGroup.Decode(state.hGroup0, br);
HuffmanTreeGroup.Decode(state.hGroup1, br);
HuffmanTreeGroup.Decode(state.hGroup2, br);
state.contextMapSlice = 0;
state.distContextMapSlice = 0;
state.contextLookupOffset1 = Context.LookupOffsets[state.contextModes[0]];
state.contextLookupOffset2 = Context.LookupOffsets[state.contextModes[0] + 1];
state.literalTreeIndex = 0;
state.literalTree = state.hGroup0.trees[0];
state.treeCommandOffset = state.hGroup1.trees[0];
// TODO: == 0?
state.blockTypeRb[0] = state.blockTypeRb[2] = state.blockTypeRb[4] = 1;
state.blockTypeRb[1] = state.blockTypeRb[3] = state.blockTypeRb[5] = 0;
}
private static void DecodeDistanceBlockSwitch(BrotliState state)
{
DecodeBlockTypeAndLength(state, 2);
state.distContextMapSlice = state.blockTypeRb[5] << DistanceContextBits;
}
private static void DecodeCommandBlockSwitch(BrotliState state)
{
DecodeBlockTypeAndLength(state, 1);
state.treeCommandOffset = state.hGroup1.trees[state.blockTypeRb[3]];
}