DEFINITION MODULE IOErrorCodes;

	(********************************************************)
	(*							*)
	(*		I/O subsystem error codes.		*)
	(*							*)
	(*  This module defines a set of error codes which may	*)
	(*  be used uniformly throughout the file system.	*)
	(*							*)
	(*  Programmer:		P. Moylan			*)
	(*  Last edited:	11 May 1994			*)
	(*  Status:		OK				*)
	(*							*)
	(********************************************************)


TYPE
    ErrorCode = (

	OK,			(* Normal return, no error	*)
	OperationAborted,	(* Operator forced abort	*)

	(* Error codes from module Files.	*)

	FileNotOpen,		(* Should have opened file first  *)

	(* Error codes from module Devices.	*)

	NoSuchDevice,		(* Illegal device *)
	NoSuchUnit,		(* Illegal unit number *)

	(* Error codes from module Directories.	*)

	FeatureNotImplemented,	(* Cannot yet handle this case *)
	InvalidFileNameString,	(* Could not parse filename string *)
	DirectoryNotFound,	(* Subdirectory name not found *)
	NotADirectory,		(* Supposed directory name is not a dir	*)
	NameNotFound,		(* File name not found in directory *)
	DuplicateFileName,	(* File name already exists *)
	DeviceFull,		(* No room to create/extend file *)
	DirectoryFull,		(* No room to create new directory entry *)

	(* Error codes from the disk device drivers.	*)

	BadDMAAddress,		(* Operation uses a memory buffer which	*)
				(* the DMA hardware cannot handle	*)
	IllegalBlockNumber,	(* The caller requested an operation on	*)
				(*  a non-existent disk block.		*)
	BadCommand,		(* We tried to do something illegal.	*)
	ControllerNotListening,	(* Could not get the disk controller	*)
				(*  to accept a command.		*)
	ControllerOutOfSync,	(* Status information from the disk	*)
				(*  controller does not make sense.	*)
	TimeoutError,		(* Data request interrupt did not	*)
				(*  arrive within a reasonable time.	*)
	CalibrationFailure,	(* Did not succeed in driving the head	*)
				(*  back to its home position.		*)
	SeekFailure,		(* Failed to seek to the desired track.	*)
	DriveNotReady,		(* Could be an equipment failure, but	*)
				(*  more commonly means that the drive	*)
				(*  door is open or there is no disk in	*)
				(*  the drive.				*)
	SectorNotFound,		(* Missing sector, cylinder mismatch,	*)
				(*  and similar errors.  This could	*)
				(*  mean a badly formatted disk, it	*)
				(*  could be just one faulty block, or	*)
				(*  it could mean that a recalibration	*)
				(*  is needed.				*)
	BadBlock,		(* The sector has its "bad block"	*)
				(*  mark set - should not be used.	*)
	BadData,		(* Something on the disk is corrupted.	*)
				(*  Could be a transient error, e.g.	*)
				(*  read error caused by a speck of	*)
				(*  dust, but it could also be true	*)
				(*  corruption of the medium.		*)
	WriteFault,		(* Occurs only with hard disk, reflects	*)
				(*  a hardware fault signal.		*)
	WriteProtected,		(* Attempted write to a write-protected	*)
				(*  disk.				*)
	UndiagnosedFailure	(* Miscellaneous error.			*)

	);		(* End of the list of error codes *)

(************************************************************************)

PROCEDURE TranslateErrorCode (code: ErrorCode;
				VAR (*OUT*) string: ARRAY OF CHAR);

    (* Converts code to its textual representation. *)

END IOErrorCodes.