tdlight/tdutils/td/utils/Gzip.cpp

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "td/utils/Gzip.h"
char disable_linker_warning_about_empty_file_gzip_cpp TD_UNUSED;
#if TD_HAVE_ZLIB
#include "td/utils/logging.h"
#include <cstring>
#include <limits>
#include <utility>
#include <zlib.h>
namespace td {
class Gzip::Impl {
public:
z_stream stream_;
// z_stream is not copyable nor movable
Impl() = default;
Impl(const Impl &other) = delete;
Impl &operator=(const Impl &other) = delete;
Impl(Impl &&other) = delete;
Impl &operator=(Impl &&other) = delete;
~Impl() = default;
};
Status Gzip::init_encode() {
CHECK(mode_ == Mode::Empty);
init_common();
mode_ = Mode::Encode;
int ret = deflateInit2(&impl_->stream_, 6, Z_DEFLATED, 15, MAX_MEM_LEVEL, Z_DEFAULT_STRATEGY);
if (ret != Z_OK) {
return Status::Error(PSLICE() << "zlib deflate init failed: " << ret);
}
return Status::OK();
}
Status Gzip::init_decode() {
CHECK(mode_ == Mode::Empty);
init_common();
mode_ = Mode::Decode;
int ret = inflateInit2(&impl_->stream_, MAX_WBITS + 32);
if (ret != Z_OK) {
return Status::Error(PSLICE() << "zlib inflate init failed: " << ret);
}
return Status::OK();
}
void Gzip::set_input(Slice input) {
CHECK(input_size_ == 0);
CHECK(!close_input_flag_);
CHECK(input.size() <= std::numeric_limits<uInt>::max());
CHECK(impl_->stream_.avail_in == 0);
input_size_ = input.size();
impl_->stream_.avail_in = static_cast<uInt>(input.size());
impl_->stream_.next_in = reinterpret_cast<Bytef *>(const_cast<char *>(input.data()));
}
void Gzip::set_output(MutableSlice output) {
CHECK(output_size_ == 0);
CHECK(output.size() <= std::numeric_limits<uInt>::max());
CHECK(impl_->stream_.avail_out == 0);
output_size_ = output.size();
impl_->stream_.avail_out = static_cast<uInt>(output.size());
impl_->stream_.next_out = reinterpret_cast<Bytef *>(output.data());
}
Result<Gzip::State> Gzip::run() {
while (true) {
int ret;
if (mode_ == Mode::Decode) {
ret = inflate(&impl_->stream_, Z_NO_FLUSH);
} else {
ret = deflate(&impl_->stream_, close_input_flag_ ? Z_FINISH : Z_NO_FLUSH);
}
if (ret == Z_OK) {
return State::Running;
}
if (ret == Z_STREAM_END) {
// TODO(now): fail if input is not empty;
clear();
return State::Done;
}
clear();
return Status::Error(PSLICE() << "zlib error " << ret);
}
}
size_t Gzip::left_input() const {
return impl_->stream_.avail_in;
}
size_t Gzip::left_output() const {
return impl_->stream_.avail_out;
}
void Gzip::init_common() {
std::memset(&impl_->stream_, 0, sizeof(impl_->stream_));
impl_->stream_.zalloc = Z_NULL;
impl_->stream_.zfree = Z_NULL;
impl_->stream_.opaque = Z_NULL;
impl_->stream_.avail_in = 0;
impl_->stream_.next_in = nullptr;
impl_->stream_.avail_out = 0;
impl_->stream_.next_out = nullptr;
input_size_ = 0;
output_size_ = 0;
close_input_flag_ = false;
}
void Gzip::clear() {
if (mode_ == Mode::Decode) {
inflateEnd(&impl_->stream_);
} else if (mode_ == Mode::Encode) {
deflateEnd(&impl_->stream_);
}
mode_ = Mode::Empty;
}
Gzip::Gzip() : impl_(make_unique<Impl>()) {
}
Gzip::Gzip(Gzip &&other) : Gzip() {
swap(other);
}
Gzip &Gzip::operator=(Gzip &&other) {
CHECK(this != &other);
clear();
swap(other);
return *this;
}
void Gzip::swap(Gzip &other) {
using std::swap;
swap(impl_, other.impl_);
swap(input_size_, other.input_size_);
swap(output_size_, other.output_size_);
swap(close_input_flag_, other.close_input_flag_);
swap(mode_, other.mode_);
}
Gzip::~Gzip() {
clear();
}
BufferSlice gzdecode(Slice s) {
Gzip gzip;
gzip.init_decode().ensure();
ChainBufferWriter message;
gzip.set_input(s);
gzip.close_input();
double k = 2;
gzip.set_output(message.prepare_append(static_cast<size_t>(static_cast<double>(s.size()) * k)));
while (true) {
auto r_state = gzip.run();
if (r_state.is_error()) {
return BufferSlice();
}
auto state = r_state.ok();
if (state == Gzip::State::Done) {
message.confirm_append(gzip.flush_output());
break;
}
if (gzip.need_input()) {
return BufferSlice();
}
if (gzip.need_output()) {
message.confirm_append(gzip.flush_output());
k *= 1.5;
gzip.set_output(message.prepare_append(static_cast<size_t>(static_cast<double>(gzip.left_input()) * k)));
}
}
return message.extract_reader().move_as_buffer_slice();
}
BufferSlice gzencode(Slice s, double max_compression_ratio) {
Gzip gzip;
gzip.init_encode().ensure();
gzip.set_input(s);
gzip.close_input();
size_t max_size = static_cast<size_t>(static_cast<double>(s.size()) * max_compression_ratio);
BufferWriter message{max_size};
gzip.set_output(message.prepare_append());
auto r_state = gzip.run();
if (r_state.is_error()) {
return BufferSlice();
}
auto state = r_state.ok();
if (state != Gzip::State::Done) {
return BufferSlice();
}
message.confirm_append(gzip.flush_output());
return message.as_buffer_slice();
}
} // namespace td
#endif