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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* 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.
*/
#include <AK/ByteBuffer.h>
#include <AK/Optional.h>
#include <LibCore/Gzip.h>
#include <LibCore/puff.h>
#include <limits.h>
#include <stddef.h>
//#define DEBUG_GZIP
namespace Core {
bool Gzip::is_compressed(const ByteBuffer& data)
{
return data.size() > 2 && data[0] == 0x1F && data[1] == 0x8b;
}
// skips the gzip header
// see: https://tools.ietf.org/html/rfc1952#page-5
static Optional<ByteBuffer> get_gzip_payload(const ByteBuffer& data)
{
size_t current = 0;
auto read_byte = [&]() {
if (current >= data.size()) {
ASSERT_NOT_REACHED();
return (u8)0;
}
// dbg() << "read_byte: " << String::format("%x", data[current]);
return data[current++];
};
#ifdef DEBUG_GZIP
dbgln("get_gzip_payload: Skipping over gzip header.");
#endif
// Magic Header
if (read_byte() != 0x1F || read_byte() != 0x8B) {
dbgln("get_gzip_payload: Wrong magic number.");
return Optional<ByteBuffer>();
}
// Compression method
auto method = read_byte();
if (method != 8) {
dbg() << "get_gzip_payload: Wrong compression method = " << method;
return Optional<ByteBuffer>();
}
u8 flags = read_byte();
// Timestamp, Extra flags, OS
current += 6;
// FEXTRA
if (flags & 4) {
u16 length = read_byte() & read_byte() << 8;
dbg() << "get_gzip_payload: Header has FEXTRA flag set. Length = " << length;
current += length;
}
// FNAME
if (flags & 8) {
dbgln("get_gzip_payload: Header has FNAME flag set.");
while (read_byte() != '\0')
;
}
// FCOMMENT
if (flags & 16) {
dbgln("get_gzip_payload: Header has FCOMMENT flag set.");
while (read_byte() != '\0')
;
}
// FHCRC
if (flags & 2) {
dbgln("get_gzip_payload: Header has FHCRC flag set.");
current += 2;
}
auto new_size = data.size() - current;
#ifdef DEBUG_GZIP
dbg() << "get_gzip_payload: Returning slice from " << current << " with size " << new_size;
#endif
return data.slice(current, new_size);
}
Optional<ByteBuffer> Gzip::decompress(const ByteBuffer& data)
{
ASSERT(is_compressed(data));
#ifdef DEBUG_GZIP
dbg() << "Gzip::decompress: Decompressing gzip compressed data. Size = " << data.size();
#endif
auto optional_payload = get_gzip_payload(data);
if (!optional_payload.has_value()) {
return Optional<ByteBuffer>();
}
auto source = optional_payload.value();
unsigned long source_len = source.size();
auto destination = ByteBuffer::create_uninitialized(1024);
while (true) {
unsigned long destination_len = destination.size();
#ifdef DEBUG_GZIP
dbg() << "Gzip::decompress: Calling puff()\n"
<< " destination_data = " << destination.data() << "\n"
<< " destination_len = " << destination_len << "\n"
<< " source_data = " << source.data() << "\n"
<< " source_len = " << source_len;
#endif
auto puff_ret = puff(
destination.data(), &destination_len,
source.data(), &source_len);
if (puff_ret == 0) {
#ifdef DEBUG_GZIP
dbgln("Gzip::decompress: Decompression success.");
#endif
destination.trim(destination_len);
break;
}
if (puff_ret == 1) {
// FIXME: Find a better way of decompressing without needing to try over and over again.
#ifdef DEBUG_GZIP
dbgln("Gzip::decompress: Output buffer exhausted. Growing.");
#endif
destination.grow(destination.size() * 2);
} else {
dbg() << "Gzip::decompress: Error. puff() returned: " << puff_ret;
ASSERT_NOT_REACHED();
}
}
return destination;
}
}
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