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LibCompress: Don't assume zlib header is available right away

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Instead of checking the header in ZlibDecompressor::create(), we now
check it in read_some() when it is called for the first time. This
resolves a FIXME in the new DecompressionStream implementation.
This commit is contained in:
Valtteri Koskivuori 2024-11-18 20:16:55 +02:00 • committed by Tim Flynn
commit 135daeb8bb
Notes: github-actions[bot] 2024-11-19 00:56:46 +00:00
6 changed files with 45 additions and 24 deletions
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38
Libraries/LibCompress/Zlib.cpp
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@ -17,31 +17,35 @@ namespace Compress {
ErrorOr<NonnullOwnPtr<ZlibDecompressor>> ZlibDecompressor::create(MaybeOwned<Stream> stream)
{
auto header = TRY(stream->read_value<ZlibHeader>());
if (header.compression_method != ZlibCompressionMethod::Deflate || header.compression_info > 7)
return Error::from_string_literal("Non-DEFLATE compression inside Zlib is not supported");
if (header.present_dictionary)
return Error::from_string_literal("Zlib compression with a pre-defined dictionary is currently not supported");
if (header.as_u16 % 31 != 0)
return Error::from_string_literal("Zlib error correction code does not match");
auto bit_stream = make<LittleEndianInputBitStream>(move(stream));
auto deflate_stream = TRY(Compress::DeflateDecompressor::construct(move(bit_stream)));
return adopt_nonnull_own_or_enomem(new (nothrow) ZlibDecompressor(header, move(deflate_stream)));
return adopt_nonnull_own_or_enomem(new (nothrow) ZlibDecompressor(move(stream)));
}
ZlibDecompressor::ZlibDecompressor(ZlibHeader header, NonnullOwnPtr<Stream> stream)
: m_header(header)
ZlibDecompressor::ZlibDecompressor(MaybeOwned<Stream> stream)
: m_has_seen_header(false)
, m_stream(move(stream))
{
}
ErrorOr<Bytes> ZlibDecompressor::read_some(Bytes bytes)
{
if (!m_has_seen_header) {
auto header = TRY(m_stream->read_value<ZlibHeader>());
if (header.compression_method != ZlibCompressionMethod::Deflate || header.compression_info > 7)
return Error::from_string_literal("Non-DEFLATE compression inside Zlib is not supported");
if (header.present_dictionary)
return Error::from_string_literal("Zlib compression with a pre-defined dictionary is currently not supported");
if (header.as_u16 % 31 != 0)
return Error::from_string_literal("Zlib error correction code does not match");
auto bit_stream = make<LittleEndianInputBitStream>(move(m_stream));
auto deflate_stream = TRY(Compress::DeflateDecompressor::construct(move(bit_stream)));
m_stream = move(deflate_stream);
m_has_seen_header = true;
}
return m_stream->read_some(bytes);
}