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LibCompress: Implement GZip compression

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This commit implements a stream compressor for the gzip
specification (RFC 1952), which is essentially a thin
wrapper around the DEFLATE compression format.
This commit is contained in:
Idan Horowitz 2021-03-13 01:26:44 +02:00 • committed by Andreas Kling
parent 02569bec11
commit 135751c3a2
2 changed files with 94 additions and 25 deletions
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60
Userland/Libraries/LibCompress/Gzip.h
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@ -1,5 +1,6 @@
/*
* Copyright (c) 2020, the SerenityOS developers.
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -33,6 +34,28 @@ namespace Compress {
constexpr u8 gzip_magic_1 = 0x1f;
constexpr u8 gzip_magic_2 = 0x8b;
struct [[gnu::packed]] BlockHeader {
u8 identification_1;
u8 identification_2;
u8 compression_method;
u8 flags;
LittleEndian<u32> modification_time;
u8 extra_flags;
u8 operating_system;
bool valid_magic_number() const;
bool supported_by_implementation() const;
};
struct Flags {
static constexpr u8 FTEXT = 1 << 0;
static constexpr u8 FHCRC = 1 << 1;
static constexpr u8 FEXTRA = 1 << 2;
static constexpr u8 FNAME = 1 << 3;
static constexpr u8 FCOMMENT = 1 << 4;
static constexpr u8 MAX = FTEXT | FHCRC | FEXTRA | FNAME | FCOMMENT;
};
class GzipDecompressor final : public InputStream {
public:
@ -49,29 +72,6 @@ public:
static bool is_likely_compressed(ReadonlyBytes bytes);
private:
struct [[gnu::packed]] BlockHeader {
u8 identification_1;
u8 identification_2;
u8 compression_method;
u8 flags;
LittleEndian<u32> modification_time;
u8 extra_flags;
u8 operating_system;
bool valid_magic_number() const;
bool supported_by_implementation() const;
};
struct Flags {
static constexpr u8 FTEXT = 1 << 0;
static constexpr u8 FHCRC = 1 << 1;
static constexpr u8 FEXTRA = 1 << 2;
static constexpr u8 FNAME = 1 << 3;
static constexpr u8 FCOMMENT = 1 << 4;
static constexpr u8 MAX = FTEXT | FHCRC | FEXTRA | FNAME | FCOMMENT;
};
class Member {
public:
Member(BlockHeader header, InputStream& stream)
@ -95,4 +95,18 @@ private:
bool m_eof { false };
};
class GzipCompressor final : public OutputStream {
public:
GzipCompressor(OutputStream&);
~GzipCompressor();
size_t write(ReadonlyBytes) override;
bool write_or_error(ReadonlyBytes) override;
static Optional<ByteBuffer> compress_all(const ReadonlyBytes& bytes);
private:
OutputStream& m_output_stream;
};
}