// ***************************************************************************** // * This file is part of the FreeFileSync project. It is distributed under * // * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0 * // * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved * // ***************************************************************************** #ifndef ZLIB_WRAP_H_428597064566 #define ZLIB_WRAP_H_428597064566 #include "serialize.h" #include "sys_error.h" namespace zen { // compression level must be between 0 and 9: // 0: no compression // 9: best compression template <class BinContainer> //as specified in serialize.h BinContainer compress(const BinContainer& stream, int level); //throw SysError //caveat: output stream is physically larger than input! => strip additional reserved space if needed: "BinContainer(output.begin(), output.end())" template <class BinContainer> BinContainer decompress(const BinContainer& stream); //throw SysError class InputStreamAsGzip //convert input stream into gzip on the fly { public: explicit InputStreamAsGzip( //throw SysError const std::function<size_t(void* buffer, size_t bytesToRead)>& readBlock /*throw X; returning 0 signals EOF: Posix read() semantics*/); ~InputStreamAsGzip(); size_t read(void* buffer, size_t bytesToRead); //throw SysError, X; return "bytesToRead" bytes unless end of stream! private: class Impl; const std::unique_ptr<Impl> pimpl_; }; std::string compressAsGzip(const void* buffer, size_t bufSize); //throw SysError //######################## implementation ########################## namespace impl { size_t zlib_compressBound(size_t len); size_t zlib_compress (const void* src, size_t srcLen, void* trg, size_t trgLen, int level); //throw SysError size_t zlib_decompress(const void* src, size_t srcLen, void* trg, size_t trgLen); //throw SysError } template <class BinContainer> BinContainer compress(const BinContainer& stream, int level) //throw SysError { BinContainer contOut; if (!stream.empty()) //don't dereference iterator into empty container! { //save uncompressed stream size for decompression const uint64_t uncompressedSize = stream.size(); //use portable number type! contOut.resize(sizeof(uncompressedSize)); std::memcpy(&contOut[0], &uncompressedSize, sizeof(uncompressedSize)); const size_t bufferEstimate = impl::zlib_compressBound(stream.size()); //upper limit for buffer size, larger than input size!!! contOut.resize(contOut.size() + bufferEstimate); const size_t bytesWritten = impl::zlib_compress(&*stream.begin(), stream.size(), &*contOut.begin() + contOut.size() - bufferEstimate, bufferEstimate, level); //throw SysError if (bytesWritten < bufferEstimate) contOut.resize(contOut.size() - (bufferEstimate - bytesWritten)); //caveat: unsigned arithmetics //caveat: physical memory consumption still *unchanged*! } return contOut; } template <class BinContainer> BinContainer decompress(const BinContainer& stream) //throw SysError { BinContainer contOut; if (!stream.empty()) //don't dereference iterator into empty container! { //retrieve size of uncompressed data uint64_t uncompressedSize = 0; //use portable number type! if (stream.size() < sizeof(uncompressedSize)) throw SysError(L"zlib error: stream size < 8"); std::memcpy(&uncompressedSize, &*stream.begin(), sizeof(uncompressedSize)); //attention: contOut MUST NOT be empty! Else it will pass a nullptr to zlib_decompress() => Z_STREAM_ERROR although "uncompressedSize == 0"!!! //secondary bug: don't dereference iterator into empty container! if (uncompressedSize == 0) //cannot be 0: compress() directly maps empty -> empty container skipping zlib! throw SysError(L"zlib error: uncompressed size == 0"); try { contOut.resize(static_cast<size_t>(uncompressedSize)); //throw std::bad_alloc } //most likely this is due to data corruption: catch (const std::length_error& e) { throw SysError(L"zlib error: " + _("Out of memory.") + L' ' + utfTo<std::wstring>(e.what())); } catch (const std::bad_alloc& e) { throw SysError(L"zlib error: " + _("Out of memory.") + L' ' + utfTo<std::wstring>(e.what())); } const size_t bytesWritten = impl::zlib_decompress(&*stream.begin() + sizeof(uncompressedSize), stream.size() - sizeof(uncompressedSize), &*contOut.begin(), static_cast<size_t>(uncompressedSize)); //throw SysError if (bytesWritten != static_cast<size_t>(uncompressedSize)) throw SysError(formatSystemError("zlib_decompress", L"", L"bytes written != uncompressed size.")); } return contOut; } } #endif //ZLIB_WRAP_H_428597064566