OFInflateStream.m

/*
 * Copyright (c) 2008-2026 Jonathan Schleifer <js@nil.im>
 *
 * All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License version 3.0 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * version 3.0 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * version 3.0 along with this program. If not, see
 * <https://www.gnu.org/licenses/>.
 */
 
#include "config.h"
 
#include <stdlib.h>
#include <string.h>
 
#ifndef OF_INFLATE64_STREAM_M
# import "OFInflateStream.h"
#else
# import "OFInflate64Stream.h"
# define OFInflateStream OFInflate64Stream
#endif
#import "OFHuffmanTree.h"
 
#import "OFInitializationFailedException.h"
#import "OFInvalidFormatException.h"
#import "OFNotOpenException.h"
#import "OFOutOfMemoryException.h"
 
#ifndef OF_INFLATE64_STREAM_M
# define bufferSize OFInflateStreamBufferSize
#else
# define bufferSize OFInflate64StreamBufferSize
#endif
 
enum State {
    stateBlockHeader,
    stateUncompressedBlockHeader,
    stateUncompressedBlock,
    stateHuffmanTree,
    stateHuffmanBlock
};
 
enum HuffmanState {
    huffmanStateWriteValue,
    huffmanStateAwaitCode,
    huffmanStateAwaitLengthExtraBits,
    huffmanStateAwaitDistance,
    huffmanStateAwaitDistanceExtraBits,
    huffmanStateProcessPair
};
 
#ifndef OF_INFLATE64_STREAM_M
static const uint8_t numDistanceCodes = 30;
static const uint8_t lengthCodes[29] = {
    /* indices are -257, values -3 */
    0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
    64, 80, 96, 112, 128, 160, 192, 224, 255
};
static const uint8_t lengthExtraBits[29] = {
    0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4,
    5, 5, 5, 5, 0
};
static const uint16_t distanceCodes[30] = {
    1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385,
    513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577
};
static const uint8_t distanceExtraBits[30] = {
    0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10,
    10, 11, 11, 12, 12, 13, 13
};
#else
static const uint8_t numDistanceCodes = 32;
static const uint8_t lengthCodes[29] = {
    /* indices are -257, values -3 */
    0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
    64, 80, 96, 112, 128, 160, 192, 224, 0
};
static const uint8_t lengthExtraBits[29] = {
    0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4,
    5, 5, 5, 5, 16
};
static const uint16_t distanceCodes[32] = {
    1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385,
    513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577,
    32769, 49153
};
static const uint8_t distanceExtraBits[32] = {
    0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10,
    10, 11, 11, 12, 12, 13, 13, 14, 14
};
#endif
static const uint8_t codeLengthsOrder[19] = {
    16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
};
static OFHuffmanTree fixedLitLenTree, fixedDistTree;
 
@implementation OFInflateStream
@synthesize underlyingStream = _stream;
 
static OF_INLINE bool
tryReadBits(OFInflateStream *stream, uint16_t *bits, uint8_t count)
{
    uint16_t ret = stream->_savedBits;
 
    OFAssert(stream->_savedBitsLength < count);
 
    for (uint_fast8_t i = stream->_savedBitsLength; i < count; i++) {
        if OF_UNLIKELY (stream->_bitIndex == 8) {
            if OF_LIKELY (stream->_bufferIndex <
                stream->_bufferLength)
                stream->_byte =
                    stream->_buffer[stream->_bufferIndex++];
            else {
                size_t length = [stream->_stream
                    readIntoBuffer: stream->_buffer
                        length: bufferSize];
 
                if OF_UNLIKELY (length < 1) {
                    stream->_savedBits = ret;
                    stream->_savedBitsLength = i;
                    return false;
                }
 
                stream->_byte = stream->_buffer[0];
                stream->_bufferIndex = 1;
                stream->_bufferLength = (uint16_t)length;
            }
 
            stream->_bitIndex = 0;
        }
 
        ret |= ((stream->_byte >> stream->_bitIndex++) & 1) << i;
    }
 
    stream->_savedBits = 0;
    stream->_savedBitsLength = 0;
    *bits = ret;
 
    return true;
}
 
+ (void)initialize
{
    uint8_t lengths[288];
 
    if (self != [OFInflateStream class])
        return;
 
    for (uint16_t i = 0; i <= 143; i++)
        lengths[i] = 8;
    for (uint16_t i = 144; i <= 255; i++)
        lengths[i] = 9;
    for (uint16_t i = 256; i <= 279; i++)
        lengths[i] = 7;
    for (uint16_t i = 280; i <= 287; i++)
        lengths[i] = 8;
 
    fixedLitLenTree = _OFHuffmanTreeNew(lengths, 288);
 
    for (uint16_t i = 0; i <= 31; i++)
        lengths[i] = 5;
 
    fixedDistTree = _OFHuffmanTreeNew(lengths, 32);
}
 
+ (instancetype)streamWithStream: (OFStream *)stream
{
    return objc_autoreleaseReturnValue(
        [[self alloc] initWithStream: stream]);
}
 
- (instancetype)init
{
    OF_INVALID_INIT_METHOD
}
 
- (instancetype)initWithStream: (OFStream *)stream
{
    self = [super init];
 
    @try {
        _stream = objc_retain(stream);
 
        /* 0-7 address the bit, 8 means fetch next byte */
        _bitIndex = 8;
 
#ifdef OF_INFLATE64_STREAM_M
        _slidingWindowMask = 0xFFFF;
#else
        _slidingWindowMask = 0x7FFF;
#endif
        _slidingWindow = OFAllocZeroedMemory(_slidingWindowMask + 1, 1);
    } @catch (id e) {
        objc_release(self);
        @throw e;
    }
 
    return self;
}
 
- (void)dealloc
{
    if (_stream != nil)
        [self close];
 
    OFFreeMemory(_slidingWindow);
 
    if (_state == stateHuffmanTree) {
        OFFreeMemory(_context.huffmanTree.lengths);
 
        if (_context.huffmanTree.codeLenTree != NULL)
            _OFHuffmanTreeFree(_context.huffmanTree.codeLenTree);
    }
 
    if (_state == stateHuffmanTree || _state == stateHuffmanBlock) {
        if (_context.huffman.litLenTree != fixedLitLenTree)
            _OFHuffmanTreeFree(_context.huffman.litLenTree);
        if (_context.huffman.distTree != fixedDistTree)
            _OFHuffmanTreeFree(_context.huffman.distTree);
    }
 
    [super dealloc];
}
 
- (size_t)lowlevelReadIntoBuffer: (void *)buffer_
              length: (size_t)length
{
    unsigned char *buffer = buffer_;
    uint16_t bits = 0, tmp, value = 0;
    size_t bytesWritten = 0;
    unsigned char *slidingWindow;
    uint16_t slidingWindowIndex;
 
    if (_stream == nil)
        @throw [OFNotOpenException exceptionWithObject: self];
 
    if (_atEndOfStream)
        return 0;
 
start:
    switch ((enum State)_state) {
    case stateBlockHeader:
        if OF_UNLIKELY (_inLastBlock) {
            [_stream unreadFromBuffer: _buffer + _bufferIndex
                       length: _bufferLength -
                           _bufferIndex];
            _bufferIndex = _bufferLength = 0;
 
            _atEndOfStream = true;
            return bytesWritten;
        }
 
        if OF_UNLIKELY (!tryReadBits(self, &bits, 3))
            return bytesWritten;
 
        _inLastBlock = (bits & 1);
 
        switch (bits >> 1) {
        case 0: /* No compression */
            _state = stateUncompressedBlockHeader;
            _bitIndex = 8;
            _context.uncompressedHeader.position = 0;
            memset(_context.uncompressedHeader.length, 0, 4);
            break;
        case 1: /* Fixed Huffman */
            _state = stateHuffmanBlock;
            _context.huffman.state = huffmanStateAwaitCode;
            _context.huffman.litLenTree = fixedLitLenTree;
            _context.huffman.distTree = fixedDistTree;
            _context.huffman.treeIter = fixedLitLenTree;
            break;
        case 2: /* Dynamic Huffman */
            _state = stateHuffmanTree;
            _context.huffmanTree.lengths = NULL;
            _context.huffmanTree.receivedCount = 0;
            _context.huffmanTree.value = 0xFE;
            _context.huffmanTree.litLenCodesCount = 0xFF;
            _context.huffmanTree.distCodesCount = 0xFF;
            _context.huffmanTree.codeLenCodesCount = 0xFF;
            break;
        default:
            @throw [OFInvalidFormatException exception];
        }
 
        goto start;
    case stateUncompressedBlockHeader:
#define CTX _context.uncompressedHeader
        /* FIXME: This can be done more efficiently than unreading */
        [_stream unreadFromBuffer: _buffer + _bufferIndex
                   length: _bufferLength - _bufferIndex];
        _bufferIndex = _bufferLength = 0;
 
        CTX.position += [_stream
            readIntoBuffer: CTX.length + CTX.position
                length: 4 - CTX.position];
 
        if OF_UNLIKELY (CTX.position < 4)
            return bytesWritten;
 
        if OF_UNLIKELY ((CTX.length[0] | (CTX.length[1] << 8)) !=
            (uint16_t)~(CTX.length[2] | (CTX.length[3] << 8)))
            @throw [OFInvalidFormatException exception];
 
        _state = stateUncompressedBlock;
 
        /*
         * Do not reorder! _context.uncompressed.position and
         * _context.uncompressedHeader.length overlap!
         */
        _context.uncompressed.length =
            CTX.length[0] | (CTX.length[1] << 8);
        _context.uncompressed.position = 0;
 
        goto start;
#undef CTX
    case stateUncompressedBlock:
#define CTX _context.uncompressed
        if OF_UNLIKELY (length == 0)
            return bytesWritten;
 
        tmp = (length < (size_t)CTX.length - CTX.position
            ? (uint16_t)length : CTX.length - CTX.position);
 
        tmp = (uint16_t)[_stream readIntoBuffer: buffer + bytesWritten
                         length: tmp];
 
        if OF_UNLIKELY (tmp == 0)
            return bytesWritten;
 
        slidingWindow = _slidingWindow;
        slidingWindowIndex = _slidingWindowIndex;
        for (uint_fast16_t i = 0; i < tmp; i++) {
            slidingWindow[slidingWindowIndex] =
                buffer[bytesWritten + i];
            slidingWindowIndex = (slidingWindowIndex + 1) &
                _slidingWindowMask;
        }
        _slidingWindowIndex = slidingWindowIndex;
 
        length -= tmp;
        bytesWritten += tmp;
 
        CTX.position += tmp;
        if OF_UNLIKELY (CTX.position == CTX.length)
            _state = stateBlockHeader;
 
        goto start;
#undef CTX
    case stateHuffmanTree:
#define CTX _context.huffmanTree
        if OF_LIKELY (CTX.value == 0xFE) {
            if OF_LIKELY (CTX.litLenCodesCount == 0xFF) {
                if OF_UNLIKELY (!tryReadBits(self, &bits, 5))
                    return bytesWritten;
 
                if OF_UNLIKELY (bits > 29)
                    @throw [OFInvalidFormatException
                        exception];
 
                CTX.litLenCodesCount = bits;
            }
 
            if OF_LIKELY (CTX.distCodesCount == 0xFF) {
                if OF_UNLIKELY (!tryReadBits(self, &bits, 5))
                    return bytesWritten;
 
                CTX.distCodesCount = bits;
            }
 
            if OF_LIKELY (CTX.codeLenCodesCount == 0xFF) {
                if OF_UNLIKELY (!tryReadBits(self, &bits, 4))
                    return bytesWritten;
 
                CTX.codeLenCodesCount = bits;
            }
 
            if OF_LIKELY (CTX.lengths == NULL)
                CTX.lengths = OFAllocZeroedMemory(19, 1);
 
            for (uint16_t i = CTX.receivedCount;
                i < CTX.codeLenCodesCount + 4; i++) {
                if OF_UNLIKELY (!tryReadBits(self, &bits, 3)) {
                    CTX.receivedCount = i;
                    return bytesWritten;
                }
 
                CTX.lengths[codeLengthsOrder[i]] = bits;
            }
 
            CTX.codeLenTree = _OFHuffmanTreeNew(CTX.lengths, 19);
            CTX.treeIter = CTX.codeLenTree;
 
            OFFreeMemory(CTX.lengths);
            CTX.lengths = NULL;
            CTX.receivedCount = 0;
            CTX.value = 0xFF;
        }
 
        if OF_LIKELY (CTX.lengths == NULL)
            CTX.lengths = OFAllocMemory(
                CTX.litLenCodesCount + CTX.distCodesCount + 258, 1);
 
        for (uint16_t i = CTX.receivedCount;
            i < CTX.litLenCodesCount + CTX.distCodesCount + 258;) {
            uint8_t j, count;
 
            if OF_LIKELY (CTX.value == 0xFF) {
                if OF_UNLIKELY (!_OFHuffmanTreeWalk(self,
                    tryReadBits, &CTX.treeIter, &value)) {
                    CTX.receivedCount = i;
                    return bytesWritten;
                }
 
                CTX.treeIter = CTX.codeLenTree;
 
                if (value < 16) {
                    CTX.lengths[i++] = value;
                    continue;
                }
            } else
                value = CTX.value;
 
            switch (value) {
            case 16:
                if OF_UNLIKELY (i < 1)
                    @throw [OFInvalidFormatException
                        exception];
 
                if OF_UNLIKELY (!tryReadBits(self, &bits, 2)) {
                    CTX.receivedCount = i;
                    CTX.value = value;
                    return bytesWritten;
                }
 
                value = CTX.lengths[i - 1];
                count = bits + 3;
 
                break;
            case 17:
                if OF_UNLIKELY (!tryReadBits(self, &bits, 3)) {
                    CTX.receivedCount = i;
                    CTX.value = value;
                    return bytesWritten;
                }
 
                value = 0;
                count = bits + 3;
 
                break;
            case 18:
                if OF_UNLIKELY (!tryReadBits(self, &bits, 7)) {
                    CTX.receivedCount = i;
                    CTX.value = value;
                    return bytesWritten;
                }
 
                value = 0;
                count = bits + 11;
 
                break;
            default:
                @throw [OFInvalidFormatException exception];
            }
 
            if OF_UNLIKELY (i + count >
                CTX.litLenCodesCount + CTX.distCodesCount + 258)
                @throw [OFInvalidFormatException exception];
 
            for (j = 0; j < count; j++)
                CTX.lengths[i++] = value;
 
            CTX.value = 0xFF;
        }
 
        _OFHuffmanTreeFree(CTX.codeLenTree);
        CTX.codeLenTree = NULL;
 
        CTX.litLenTree = _OFHuffmanTreeNew(CTX.lengths,
            CTX.litLenCodesCount + 257);
        CTX.distTree = _OFHuffmanTreeNew(
            CTX.lengths + CTX.litLenCodesCount + 257,
            CTX.distCodesCount + 1);
 
        OFFreeMemory(CTX.lengths);
 
        /*
         * litLenTree and distTree are at the same location in
         * _context.huffman and _context.huffmanTree, thus no need to
         * set them.
         */
        _state = stateHuffmanBlock;
        _context.huffman.state = huffmanStateAwaitCode;
        _context.huffman.treeIter = CTX.litLenTree;
 
        goto start;
#undef CTX
    case stateHuffmanBlock:
#define CTX _context.huffman
        for (;;) {
            uint8_t extraBits, lengthCodeIndex;
 
            if OF_UNLIKELY (CTX.state == huffmanStateWriteValue) {
                if OF_UNLIKELY (length == 0)
                    return bytesWritten;
 
                buffer[bytesWritten++] = CTX.value;
                length--;
 
                _slidingWindow[_slidingWindowIndex] = CTX.value;
                _slidingWindowIndex =
                    (_slidingWindowIndex + 1) &
                    _slidingWindowMask;
 
                CTX.state = huffmanStateAwaitCode;
                CTX.treeIter = CTX.litLenTree;
            }
 
            if OF_UNLIKELY (CTX.state ==
                huffmanStateAwaitLengthExtraBits) {
                if OF_UNLIKELY (!tryReadBits(self, &bits,
                    CTX.extraBits))
                    return bytesWritten;
 
                CTX.length += bits;
 
                CTX.state = huffmanStateAwaitDistance;
                CTX.treeIter = CTX.distTree;
            }
 
            /* Distance of length distance pair */
            if (CTX.state == huffmanStateAwaitDistance) {
                if OF_UNLIKELY (!_OFHuffmanTreeWalk(self,
                    tryReadBits, &CTX.treeIter, &value))
                    return bytesWritten;
 
                if OF_UNLIKELY (value >= numDistanceCodes)
                    @throw [OFInvalidFormatException
                        exception];
 
                CTX.distance = distanceCodes[value];
                extraBits = distanceExtraBits[value];
 
                if (extraBits > 0) {
                    if OF_UNLIKELY (!tryReadBits(self,
                        &bits, extraBits)) {
#define HSADEB huffmanStateAwaitDistanceExtraBits
                        CTX.state = HSADEB;
#undef HSADEB
                        CTX.extraBits = extraBits;
                        return bytesWritten;
                    }
 
                    CTX.distance += bits;
                }
 
                CTX.state = huffmanStateProcessPair;
            } else if (CTX.state ==
                huffmanStateAwaitDistanceExtraBits) {
                if OF_UNLIKELY (!tryReadBits(self, &bits,
                    CTX.extraBits))
                    return bytesWritten;
 
                CTX.distance += bits;
 
                CTX.state = huffmanStateProcessPair;
            }
 
            /* Length distance pair */
            if (CTX.state == huffmanStateProcessPair) {
                for (uint_fast16_t j = 0; j < CTX.length; j++) {
                    uint16_t idx;
 
                    if OF_UNLIKELY (length == 0) {
                        CTX.length -= j;
                        return bytesWritten;
                    }
 
                    idx = (_slidingWindowIndex -
                        CTX.distance) & _slidingWindowMask;
                    value = _slidingWindow[idx];
 
                    buffer[bytesWritten++] = value;
                    length--;
 
                    _slidingWindow[_slidingWindowIndex] =
                        value;
                    _slidingWindowIndex =
                        (_slidingWindowIndex + 1) &
                        _slidingWindowMask;
                }
 
                CTX.state = huffmanStateAwaitCode;
                CTX.treeIter = CTX.litLenTree;
            }
 
            if OF_UNLIKELY (!_OFHuffmanTreeWalk(self, tryReadBits,
                &CTX.treeIter, &value))
                return bytesWritten;
 
            /* End of block */
            if OF_UNLIKELY (value == 256) {
                if (CTX.litLenTree != fixedLitLenTree)
                    _OFHuffmanTreeFree(CTX.litLenTree);
                if (CTX.distTree != fixedDistTree)
                    _OFHuffmanTreeFree(CTX.distTree);
 
                _state = stateBlockHeader;
                goto start;
            }
 
            /* Literal byte */
            if OF_LIKELY (value < 256) {
                if OF_UNLIKELY (length == 0) {
                    CTX.state = huffmanStateWriteValue;
                    CTX.value = value;
                    return bytesWritten;
                }
 
                buffer[bytesWritten++] = value;
                length--;
 
                _slidingWindow[_slidingWindowIndex] = value;
                _slidingWindowIndex =
                    (_slidingWindowIndex + 1) &
                    _slidingWindowMask;
 
                CTX.treeIter = CTX.litLenTree;
                continue;
            }
 
            if OF_UNLIKELY (value > 285)
                @throw [OFInvalidFormatException exception];
 
            /* Length of length distance pair */
            lengthCodeIndex = value - 257;
            CTX.length = lengthCodes[lengthCodeIndex] + 3;
            extraBits = lengthExtraBits[lengthCodeIndex];
 
            if (extraBits > 0) {
                if OF_UNLIKELY (!tryReadBits(self, &bits,
                    extraBits)) {
                    CTX.extraBits = extraBits;
                    CTX.state =
                        huffmanStateAwaitLengthExtraBits;
                    return bytesWritten;
                }
 
                CTX.length += bits;
            }
 
            CTX.treeIter = CTX.distTree;
            CTX.state = huffmanStateAwaitDistance;
        }
 
        break;
#undef CTX
    }
 
    OF_UNREACHABLE
}
 
- (bool)lowlevelIsAtEndOfStream
{
    if (_stream == nil)
        @throw [OFNotOpenException exceptionWithObject: self];
 
    return _atEndOfStream;
}
 
- (int)fileDescriptorForReading
{
    return ((id <OFReadyForReadingObserving>)_stream)
        .fileDescriptorForReading;
}
 
- (bool)lowlevelHasDataInReadBuffer
{
    return (_stream.hasDataInReadBuffer ||
        _bufferLength - _bufferIndex > 0);
}
 
- (void)close
{
    if (_stream == nil)
        @throw [OFNotOpenException exceptionWithObject: self];
 
    /* Give back our buffer to the stream, in case it's shared */
    [_stream unreadFromBuffer: _buffer + _bufferIndex
               length: _bufferLength - _bufferIndex];
    _bufferIndex = _bufferLength = 0;
 
    objc_release(_stream);
    _stream = nil;
 
    [super close];
}
@end