Object IOFile

Object IOFile serves for realization of interaction with:

• Consoles
• Communications resources
• Directories (open only)
• Disk devices
• Files
• Mailslots
• Pipes 

Server subroutines

Communications Resource

A process uses the OPENCOMFILE function to open a handle to a communications resource. For example, specifying COM1 opens a handle to a serial port, and LPT1 opens a handle to a parallel port. If the specified resource is currently being used by another process, CreateFile fails. Any thread of the process can use the handle returned by CreateFile to identify the resource in any of the functions that access the resource.

When using CreateFile to open a handle directly to a device, an application must use the special characters " \\ .\" to identify the device. For example, to open a handle to drive A, specify " \\ .\a:" for the lpszName parameter of CreateFile. The calling process can use the handle in the DeviceIoControl function to send control codes to the device.

When the process calls CreateFile to open a communications resource, it specifies the following attributes:

• What type of read/write access exists for the specified resource.
• Whether the handle can be inherited by child processes.
• Whether the handle can be used in overlapped (asynchronous) I/O operations. (For a description of overlapped operations, see Synchronization.)

When the process uses OPENCOMFILE TO OPEN A COMMUNICATIONS resource, it must specify certain values for the following parameters:

• The fdwShareMode parameter must be zero, opening the resource for exclusive access.
• The fdwCreate parameter must specify the OPEN_EXISTING flag.
• The hTemplateFile parameter must be NULL.

Methods

GETTYPE	Returns type IOFile
OPENCOMFILE	Opens communication port.
CLOSEHANDLE	Closing of the communication port open by method  OPENCOMFILE
SETSTYLE	Sets styles
GetStyle	Returns styles
SETSUBNAME	Sets a name of the server subroutine which will be caused at occurrence of events
GETSUBNAME	Retrieves a name of the server subroutine
READ	Reads the information
WRITE	Writes the information
WRITESTR	Writes a string, coming to an end line feed.
WRITECHAR	Writes the symbol
READSTR	Reads the string
ReadChar	Reads  the symbol
WRITEBLOCK	Writes the block
READBLOCK	Reads the block
SETDCB	Sets the current configuration of a communications device.
GETDCB	Retrieves the current configuration of a communications device.
SetCommState	Configures a communications device according to the specifications in a device-control block.
PURGECOMM	Discards all characters from the output or input buffer of a specified communications resource.
FlushFileBuffers	Clears the buffers for the specified file and causes all buffered data to be written to the file.
ClearCommBreak	Suspends character transmission for a specified communications device and places the transmission line in a break state.
BUILDCOMMDCB	Fills a specified DCB structure with values specified in a device-control string.
BUILDCOMMTIMEOUTS	Translates a device-definition string into appropriate device-control block codes and places them into a device control block.
SETTIMEOUTS	Sets the time-out parameters for all read and write operations on a specified communications device.
GetTimeouts	Retrieves the time-out parameters for all read and write operations on a specified communications device.
ClearCommError	Retrieves information about a communications error and reports the current status of a communications device.
COMMCONFIGDIALOG	Displays a driver-supplied configuration dialog box.
GETCOMMCONFIG	Retrieves the current configuration of a communications device.
ESCAPECOMMFUNCTION	Directs a specified communications device to perform an extended function.
GetCommMask	Retrieves the value of the event mask for a specified communications device.
SETCOMMMASK	Specifies a set of events to be monitored for a communications device.
GetCommModemStatus	Retrieves modem control-register values.
GetCommProperties	Retrieves information about the communications properties for a specified communications device.
GetCommState	Retrieves the current control settings for a specified communications device.
GetDefaultCommConfig	Retrieves the default configuration for the specified communications device.
SETCOMMBREAK	Suspends character transmission for a specified communications device and places the transmission line in a break state.
SETCOMMCONFIG	Sets the current configuration of a communications device.
SETDEFAULTCOMMCONFIG	Sets the default configuration for a communications device.
SETUPCOMM	Initializes the communications parameters for a specified communications device.
TRANSMITCOMMCHAR	Transmits a specified character ahead of any pending data in the output buffer of the specified communications device.
SETERRORMODE	Controls whether the system will handle the specified types of serious errors, or whether the process will handle them.
CANCELIO	Cancels all pending I/O operations that were issued by the calling thread for the specified file handle.
GetFileInformation	Retrieves file information for a specified file.
LOCKFILE	Locks a region in an open file.
GetFileSizeEx	Retrieves the size of a specified file.
GetFileType	Retrieves the file type of the specified file.
UNLOCKFILE	Unlocks a previously locked region in an open file.
SETFILEVALIDDATA	Sets the valid data length of the specified file.
SETFILESHORTNAME	Sets the short name for the specified file.
SetEndOfFile	Moves the end-of-file position for the specified file.
SETFILEPOINTER	Moves the file pointer of an open file.
READDIRECTORYCHANGES	Retrieves information describing the changes occurring within a directory.
SetBookMark	Sets the bookmark indicating certain item
DeleteBookMark	Deletes the bookmark
GETCRC16	Returns a check sum on algorithm CRC16 on an existing array
MOVEBOOKMARK	Moves a bookmark
ClearReadBuffer	Clears the buffer
GetArrCRC16	Returns a check sum on algorithm CRC16, after transfer to a file of an array