内存映射的封装 包含读、写文件

#include "MemoryMapReader.h" #include <windows.h> #define memfile_block_size 64*1024 //------------------------------------------------------------------------------------ class CMemoryMapReader::Impl { unsigned int file_size_; HANDLE handle_file_; HANDLE handle_map_; unsigned int cur_block_size_; unsigned int cur_block_pos_; char* cur_block_ptr_; unsigned int cur_block_offset_; public: Impl(); ~Impl(); public: bool Open(const TCHAR* path); void Close(); bool IsEOF(); unsigned int GetFileSize(); unsigned int GetReaderOffset(); bool SetReaderOffeset(const unsigned int& offset); unsigned int ReadData(void* data_buf, const unsigned int& read_len); private: bool i_OpenFile(const TCHAR* file); bool i_CreateFileMap(); bool i_MapNextBlock(); void i_CloseFileMap(); void i_CloseFile(); }; //------------------------------------------------------------------------------------ CMemoryMapReader::Impl::Impl() : handle_file_() , handle_map_() , file_size_() , cur_block_pos_() , cur_block_ptr_() , cur_block_size_() , cur_block_offset_() { } CMemoryMapReader::Impl::~Impl() { Close(); } void CMemoryMapReader::Impl::i_CloseFileMap() { if ( cur_block_ptr_ ) ::UnmapViewOfFile(cur_block_ptr_); if ( handle_map_ && (handle_map_ != INVALID_HANDLE_VALUE) ) ::CloseHandle(handle_map_); cur_block_ptr_ = 0; handle_map_ = 0; } void CMemoryMapReader::Impl::i_CloseFile() { if ( handle_file_ && (handle_file_ != INVALID_HANDLE_VALUE) ) CloseHandle(handle_file_); handle_file_ = 0; file_size_ = 0; cur_block_pos_ = 0; cur_block_ptr_ = 0; cur_block_size_ = 0; cur_block_offset_ = 0; } bool CMemoryMapReader::Impl::i_OpenFile(const TCHAR* file) { Close(); handle_file_ = ::CreateFile(file, GENERIC_READ|GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); if (handle_file_ == INVALID_HANDLE_VALUE) { return false; } file_size_ = ::GetFileSize(handle_file_, 0); // max file size : 4G return i_CreateFileMap(); } bool CMemoryMapReader::Impl::i_CreateFileMap() { do { if (file_size_ == 0xFFFFFFFF) break; handle_map_ = ::CreateFileMapping(handle_file_, 0, PAGE_READWRITE, 0, file_size_, 0); if (handle_map_ == INVALID_HANDLE_VALUE) break; cur_block_pos_ = 0; cur_block_size_ = memfile_block_size; if ((file_size_-cur_block_pos_) < memfile_block_size) { cur_block_size_ = file_size_-cur_block_pos_; // rest data of current block is less than 64K } cur_block_ptr_ = (char*)::MapViewOfFile(handle_map_, FILE_MAP_READ|FILE_MAP_WRITE, 0, cur_block_pos_, cur_block_size_); cur_block_offset_ = 0; return true; } while (0); Close(); return false; } bool CMemoryMapReader::Impl::i_MapNextBlock() { if (cur_block_ptr_) ::UnmapViewOfFile(cur_block_ptr_); cur_block_ptr_ = 0; cur_block_pos_ += cur_block_size_; if (file_size_ <= cur_block_pos_) { return false;//end of file } cur_block_size_ = memfile_block_size; if (file_size_ - cur_block_pos_ < memfile_block_size) { cur_block_size_ = file_size_ - cur_block_pos_; } cur_block_ptr_ = (char*)::MapViewOfFile(handle_map_, FILE_MAP_READ|FILE_MAP_WRITE, 0, cur_block_pos_, cur_block_size_); cur_block_offset_ = 0; return (cur_block_ptr_ != NULL); } bool CMemoryMapReader::Impl::Open(const TCHAR* path) { if (!path) return false; bool flag = i_OpenFile( path ); if (false == flag) return false; return SetReaderOffeset(0); } void CMemoryMapReader::Impl::Close() { i_CloseFileMap(); i_CloseFile(); } unsigned int CMemoryMapReader::Impl::GetFileSize() { return file_size_; } unsigned int CMemoryMapReader::Impl::GetReaderOffset() { return (cur_block_pos_ + cur_block_offset_); } bool CMemoryMapReader::Impl::IsEOF() { return (GetReaderOffset() >= file_size_); } bool CMemoryMapReader::Impl::SetReaderOffeset(const unsigned int& offset) { if (!handle_map_ || handle_map_==INVALID_HANDLE_VALUE) return false; if (file_size_ < offset) return false; unsigned int offTemp = offset; if (cur_block_ptr_) ::UnmapViewOfFile(cur_block_ptr_); cur_block_ptr_ = 0; unsigned int real_set = offTemp; if (offTemp % memfile_block_size) { offTemp = memfile_block_size * (offTemp/memfile_block_size); } real_set -= offTemp; // real_set == offset of one block cur_block_pos_ = offTemp; cur_block_size_ = memfile_block_size; if (file_size_ - cur_block_pos_ < memfile_block_size) { cur_block_size_ = file_size_ - cur_block_pos_; // rest data of current block is less than 64K } cur_block_ptr_ = (char*)::MapViewOfFile(handle_map_, FILE_MAP_READ|FILE_MAP_WRITE, 0, cur_block_pos_, cur_block_size_); cur_block_offset_ = real_set; return (cur_block_ptr_ != NULL); } unsigned int CMemoryMapReader::Impl::ReadData(void* data_buf, const unsigned int& read_len) { if (!cur_block_ptr_ || !data_buf) return 0; char* dst_buf = (char*)data_buf; unsigned int len = read_len; unsigned int rest_data; // rest len of current block while (len > 0) { rest_data = cur_block_size_ - cur_block_offset_; if (rest_data > len) rest_data = len; memcpy(dst_buf, cur_block_ptr_+cur_block_offset_, rest_data); cur_block_offset_ += rest_data; dst_buf += rest_data; len -= rest_data; if (cur_block_size_ == cur_block_offset_) { if (false == i_MapNextBlock()) { break; } } } return read_len - len; } //=================================================================================================== CMemoryMapReader::CMemoryMapReader() { self = new Impl(); } CMemoryMapReader::~CMemoryMapReader() { delete self; } bool CMemoryMapReader::Open(const TCHAR* path) { return self->Open(path); } void CMemoryMapReader::Close() { self->Close(); } unsigned int CMemoryMapReader::GetFileSize() { return self->GetFileSize(); } unsigned int CMemoryMapReader::GetReaderOffset() { return self->GetReaderOffset(); } bool CMemoryMapReader::SetReaderOffeset(const unsigned int& offset) { return self->SetReaderOffeset(offset); } bool CMemoryMapReader::IsEOF() { return self->IsEOF(); } unsigned int CMemoryMapReader::ReadData(void* data_buf, const unsigned int& read_len) { return self->ReadData(data_buf, read_len); }