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LibCompress: Convert DeflateDecompressor from recursive to iterative

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This way a deflate blob that contains a large amount of small blocks
wont cause a stack overflow.
This commit is contained in:
Idan Horowitz 2021-03-19 16:20:00 +02:00 • committed by Andreas Kling
parent b02be11a6f
commit 974a981ded
1 changed files with 92 additions and 84 deletions
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176
Userland/Libraries/LibCompress/Deflate.cpp
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@ -223,113 +223,121 @@ DeflateDecompressor::~DeflateDecompressor()
size_t DeflateDecompressor::read(Bytes bytes)
{
if (has_any_error())
return 0;
size_t total_read = 0;
while (total_read < bytes.size()) {
if (has_any_error())
break;
if (m_state == State::Idle) {
if (m_read_final_bock)
return 0;
auto slice = bytes.slice(total_read);
m_read_final_bock = m_input_stream.read_bit();
const auto block_type = m_input_stream.read_bits(2);
if (m_state == State::Idle) {
if (m_read_final_bock)
break;
if (m_input_stream.has_any_error()) {
set_fatal_error();
return 0;
}
if (block_type == 0b00) {
m_input_stream.align_to_byte_boundary();
LittleEndian<u16> length, negated_length;
m_input_stream >> length >> negated_length;
m_read_final_bock = m_input_stream.read_bit();
const auto block_type = m_input_stream.read_bits(2);
if (m_input_stream.has_any_error()) {
set_fatal_error();
return 0;
break;
}
if ((length ^ 0xffff) != negated_length) {
set_fatal_error();
return 0;
if (block_type == 0b00) {
m_input_stream.align_to_byte_boundary();
LittleEndian<u16> length, negated_length;
m_input_stream >> length >> negated_length;
if (m_input_stream.has_any_error()) {
set_fatal_error();
break;
}
if ((length ^ 0xffff) != negated_length) {
set_fatal_error();
break;
}
m_state = State::ReadingUncompressedBlock;
new (&m_uncompressed_block) UncompressedBlock(*this, length);
continue;
}
m_state = State::ReadingUncompressedBlock;
new (&m_uncompressed_block) UncompressedBlock(*this, length);
if (block_type == 0b01) {
m_state = State::ReadingCompressedBlock;
new (&m_compressed_block) CompressedBlock(*this, CanonicalCode::fixed_literal_codes(), CanonicalCode::fixed_distance_codes());
return read(bytes);
continue;
}
if (block_type == 0b10) {
CanonicalCode literal_codes;
Optional<CanonicalCode> distance_codes;
decode_codes(literal_codes, distance_codes);
if (m_input_stream.has_any_error()) {
set_fatal_error();
break;
}
m_state = State::ReadingCompressedBlock;
new (&m_compressed_block) CompressedBlock(*this, literal_codes, distance_codes);
continue;
}
set_fatal_error();
break;
}
if (block_type == 0b01) {
m_state = State::ReadingCompressedBlock;
new (&m_compressed_block) CompressedBlock(*this, CanonicalCode::fixed_literal_codes(), CanonicalCode::fixed_distance_codes());
if (m_state == State::ReadingCompressedBlock) {
auto nread = m_output_stream.read(slice);
return read(bytes);
}
if (block_type == 0b10) {
CanonicalCode literal_codes;
Optional<CanonicalCode> distance_codes;
decode_codes(literal_codes, distance_codes);
while (nread < slice.size() && m_compressed_block.try_read_more()) {
nread += m_output_stream.read(slice.slice(nread));
}
if (m_input_stream.has_any_error()) {
set_fatal_error();
return 0;
break;
}
m_state = State::ReadingCompressedBlock;
new (&m_compressed_block) CompressedBlock(*this, literal_codes, distance_codes);
total_read += nread;
if (nread == slice.size())
break;
return read(bytes);
m_compressed_block.~CompressedBlock();
m_state = State::Idle;
continue;
}
set_fatal_error();
return 0;
if (m_state == State::ReadingUncompressedBlock) {
auto nread = m_output_stream.read(slice);
while (nread < slice.size() && m_uncompressed_block.try_read_more()) {
nread += m_output_stream.read(slice.slice(nread));
}
if (m_input_stream.has_any_error()) {
set_fatal_error();
break;
}
total_read += nread;
if (nread == slice.size())
break;
m_uncompressed_block.~UncompressedBlock();
m_state = State::Idle;
continue;
}
VERIFY_NOT_REACHED();
}
if (m_state == State::ReadingCompressedBlock) {
auto nread = m_output_stream.read(bytes);
while (nread < bytes.size() && m_compressed_block.try_read_more()) {
nread += m_output_stream.read(bytes.slice(nread));
}
if (m_input_stream.has_any_error()) {
set_fatal_error();
return 0;
}
if (nread == bytes.size())
return nread;
m_compressed_block.~CompressedBlock();
m_state = State::Idle;
return nread + read(bytes.slice(nread));
}
if (m_state == State::ReadingUncompressedBlock) {
auto nread = m_output_stream.read(bytes);
while (nread < bytes.size() && m_uncompressed_block.try_read_more()) {
nread += m_output_stream.read(bytes.slice(nread));
}
if (m_input_stream.has_any_error()) {
set_fatal_error();
return 0;
}
if (nread == bytes.size())
return nread;
m_uncompressed_block.~UncompressedBlock();
m_state = State::Idle;
return nread + read(bytes.slice(nread));
}
VERIFY_NOT_REACHED();
return total_read;
}
bool DeflateDecompressor::read_or_error(Bytes bytes)