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LibCompress: Convert GzipDecompressor from recursive to iterative

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This way a gzip compressed file that contains a large amount of small
blocks wont cause a stack overflow.
This commit is contained in:
Idan Horowitz 2021-03-21 15:13:19 +02:00 • committed by Andreas Kling
parent 00bbe76c94
commit b3b8c01ebf
1 changed files with 77 additions and 69 deletions
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146
Userland/Libraries/LibCompress/Gzip.cpp
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@ -70,86 +70,94 @@ GzipDecompressor::~GzipDecompressor()
// FIXME: Again, there are surely a ton of bugs because the code doesn't check for read errors. // FIXME: Again, there are surely a ton of bugs because the code doesn't check for read errors.
size_t GzipDecompressor::read(Bytes bytes) size_t GzipDecompressor::read(Bytes bytes)
{ {
if (has_any_error() || m_eof) size_t total_read = 0;
return 0; while (total_read < bytes.size()) {
if (has_any_error() || m_eof)
break;
if (m_current_member.has_value()) { auto slice = bytes.slice(total_read);
size_t nread = current_member().m_stream.read(bytes);
current_member().m_checksum.update(bytes.trim(nread));
current_member().m_nread += nread;
if (current_member().m_stream.handle_any_error()) { if (m_current_member.has_value()) {
set_fatal_error(); size_t nread = current_member().m_stream.read(slice);
return 0; current_member().m_checksum.update(slice.trim(nread));
} current_member().m_nread += nread;
if (nread < bytes.size()) {
LittleEndian<u32> crc32, input_size;
m_input_stream >> crc32 >> input_size;
if (crc32 != current_member().m_checksum.digest()) {
// FIXME: Somehow the checksum is incorrect?
if (current_member().m_stream.handle_any_error()) {
set_fatal_error(); set_fatal_error();
return 0; break;
} }
if (input_size != current_member().m_nread) { if (nread < slice.size()) {
set_fatal_error(); LittleEndian<u32> crc32, input_size;
return 0; m_input_stream >> crc32 >> input_size;
if (crc32 != current_member().m_checksum.digest()) {
// FIXME: Somehow the checksum is incorrect?
set_fatal_error();
break;
}
if (input_size != current_member().m_nread) {
set_fatal_error();
break;
}
m_current_member.clear();
total_read += nread;
continue;
} }
m_current_member.clear(); total_read += nread;
continue;
} else {
m_partial_header_offset += m_input_stream.read(Bytes { m_partial_header, sizeof(BlockHeader) }.slice(m_partial_header_offset));
return nread + read(bytes.slice(nread)); if (m_input_stream.handle_any_error() || m_input_stream.unreliable_eof()) {
m_eof = true;
break;
}
if (m_partial_header_offset < sizeof(BlockHeader)) {
break; // partial header read
}
m_partial_header_offset = 0;
BlockHeader header = *(reinterpret_cast<BlockHeader*>(m_partial_header));
if (!header.valid_magic_number() || !header.supported_by_implementation()) {
set_fatal_error();
break;
}
if (header.flags & Flags::FEXTRA) {
LittleEndian<u16> subfield_id, length;
m_input_stream >> subfield_id >> length;
m_input_stream.discard_or_error(length);
}
if (header.flags & Flags::FNAME) {
String original_filename;
m_input_stream >> original_filename;
}
if (header.flags & Flags::FCOMMENT) {
String comment;
m_input_stream >> comment;
}
if (header.flags & Flags::FHCRC) {
LittleEndian<u16> crc16;
m_input_stream >> crc16;
// FIXME: we should probably verify this instead of just assuming it matches
}
m_current_member.emplace(header, m_input_stream);
continue;
} }
return nread;
} else {
m_partial_header_offset += m_input_stream.read(Bytes { m_partial_header, sizeof(BlockHeader) }.slice(m_partial_header_offset));
if (m_input_stream.handle_any_error() || m_input_stream.unreliable_eof()) {
m_eof = true;
return 0;
}
if (m_partial_header_offset < sizeof(BlockHeader)) {
return 0; // partial header read
}
m_partial_header_offset = 0;
BlockHeader header = *(reinterpret_cast<BlockHeader*>(m_partial_header));
if (!header.valid_magic_number() || !header.supported_by_implementation()) {
set_fatal_error();
return 0;
}
if (header.flags & Flags::FEXTRA) {
LittleEndian<u16> subfield_id, length;
m_input_stream >> subfield_id >> length;
m_input_stream.discard_or_error(length);
}
if (header.flags & Flags::FNAME) {
String original_filename;
m_input_stream >> original_filename;
}
if (header.flags & Flags::FCOMMENT) {
String comment;
m_input_stream >> comment;
}
if (header.flags & Flags::FHCRC) {
LittleEndian<u16> crc16;
m_input_stream >> crc16;
// FIXME: we should probably verify this instead of just assuming it matches
}
m_current_member.emplace(header, m_input_stream);
return read(bytes);
} }
return total_read;
} }
bool GzipDecompressor::read_or_error(Bytes bytes) bool GzipDecompressor::read_or_error(Bytes bytes)