BOOL BackupRead ( HANDLE hFile, LPBYTE lpBuffer, DWORD nNumberOfBytesToRead, LPDWORD lpNumberOfBytesRead, BOOL bAbort, BOOL bProcessSecurity, LPVOID* lpContext); BOOL BackupWrite ( HANDLE hFile, LPBYTE lpBuffer, DWORD nNumberOfBytesToWrite, LPDWORD lpNumberOfBytesWritten, BOOL bAbort, BOOL bProcessSecurity, LPVOID* lpContext); BOOL BackupSeek ( HANDLE hFile, DWORD dwLowBytesToSeek, DWORD dwHighBytesToSeek, LPDWORD lpdwLowByteSeeked, LPDWORD lpdwHighByteSeeked, LPVOID* lpContext);
bAbort - last call, free the context structure
lpContext - the context structure, allocated on first call