Input - Output

Files API Files are too managed with the help of handles. When handle is set it is possible to use it in input/output operations That goes for all I/O operations

CreateFile Returns file handle? What about: streams disks communications pipes etc?

lpFileName – file name dwDesiredAccess – generic access rights dwShareMode – sharing mode lpSecurityAttributes – inheritant rights dwCreationDisposition – creation mode dwFlagsAndAttributes – flags and attributes hTemplateFile – template handle

dwDesiredAccess Shows what can be done with file: GENERIC_READ GENERIC_WRITE GENERIC_EXECUTE GENERIC_ALL

dwShareMode Sharing mode of the file or device: 0 – file cannot be shared until handle is closed FILE_SHARE_READ FILE_SHARE_WRITE FILE_SHARE_DELETE

lpSecurityAttributes – saugumo požymis Protects against unwanted access NULL – handle cannot be inherited by child processes Pointer to SECURITY_ATTRIBUTES pointer to SECURITY_DESCRIPTOR recommended not to modify structure directly

dwCreationDisposition Action to take: CREATE_ALWAYS CREATE_NEW OPEN_ALWAYS OPEN_EXISTING TRUNCATE_EXISTING requires GENERIC_WRITE

dwFlagsAndAttributes File or device flags and attributes. Some flags and attributes apply to files only 0 – device is not a file Other most common flags and attributes: FILE_ATTRIBUTE_NORMAL FILE_ATTRIBUTE_HIDDEN FILE_ATTRIBUTE_READONLY FILE_ATTRIBUTE_ARCHIVE

hTemplateFile GENERIC_READ Supplies file attributes for file being created NULL – if not used Ignored when opening existing file

CreateFile2

ReadFile

ReadFileEx

Overlapped I/O Asynchronous I/O Complexity OVERLAPPED structure FileIOCompletionRoutine callback function

WriteFile

WriteFileEx

File attributes (GetFileAttributes) Commonly used attributes: FILE_ATTRIBUTE_ARCHIVE FILE_ATTRIBUTE_HIDDEN FILE_ATTRIBUTE_NORMAL FILE_ATTRIBUTE_READONLY FILE_ATTRIBUTE_SYSTEM

CopyFile lpExistingFileName – name of an existing file lpNewFileName – name of new file bFailIfExists – if TRUE existing file will not be overwritten

CopyFile2

CopyFileEx (1)

CopyFileEx (2) lpProgressRoutine – callback function (CopyProgressRoutine) lpData – argument to be passed to callback function (can be NULL) pbCancel – operation canceled if it is set to TRUE dwCopyFlags – specify, how file is to be copied

CopyProgressRoutine (1)

CopyProgressRoutine (2) TotalFileSize – file size in bytes TotalBytesTransferred – number of bytes already transferred StreamSize – size of current stream in bytes SteramBytesTransferred – number of bytes already transferred from current stream dwStreamNumber – handle to current stream dwCallbackReason – reason this function was called hSourceFile – handle to the source file hDestinationFile – handle to the destination file lpData – data from CopyFileEx function

dwCallbackReason There are two reasons: CALLBACK_CHUNK_FINISHED – part of data was copied CALLBACK_STREAM_SWITCH – another stream created and is about to be copied

CopyProgressRoutine (3) This function returns: PROGRESS_CONTINUE – continue copying PROGRESS_CANCEL – cancel copying and delete destination file PROGRESS_STOP – stop copying (can be restarted later) PROGRES_QUIET – continue copying without invoking callback function

MoveFile[Ex]

DeleteFile & RemoveDirectory

Other features Enumeration Locking Encoding Archiving Memory-mapping etc.

CloseHandle Handles must be closed When program is closing, OS automatically closes all associated handles expensive operation handle leak For sockets – closesocket For registry keys - RegCloseKey

Handle leaks When closing handle fails: Memory isn’t freed Kernel keeps all information about handle Sluggish system Crash