LibCompress: Implement gzip.

1 files changed, 92 insertions, 0 deletions

diff --git a/Libraries/LibCompress/Gzip.h b/Libraries/LibCompress/Gzip.h
new file mode 100644
index 0000000000..72e5e49aba
--- /dev/null
+++ b/Libraries/LibCompress/Gzip.h
@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <LibCompress/Deflate.h>
+#include <LibCrypto/Checksum/CRC32.h>
+
+namespace Compress {
+
+class GzipDecompressor final : public InputStream {
+public:
+    GzipDecompressor(InputStream&);
+    ~GzipDecompressor();
+
+    size_t read(Bytes) override;
+    bool read_or_error(Bytes) override;
+    bool discard_or_error(size_t) override;
+    bool eof() const override;
+
+    static ByteBuffer decompress_all(ReadonlyBytes);
+
+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)
+            : m_header(header)
+            , m_stream(stream)
+        {
+        }
+
+        BlockHeader m_header;
+        DeflateDecompressor m_stream;
+        Crypto::Checksum::CRC32 m_checksum;
+        size_t m_nread { 0 };
+    };
+
+    const Member& current_member() const { return m_current_member.value(); }
+    Member& current_member() { return m_current_member.value(); }
+
+    InputStream& m_input_stream;
+    Optional<Member> m_current_member;
+};
+
+}