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Inside Macintosh: Files /

Chapter 2 - File Manager / File Manager Reference

Utility Routines / Obtaining File Control Block Information

PBGetFCBInfo

You can use PBGetFCBInfo to get information about an open file.

FUNCTION PBGetFCBInfo (paramBlock: FCBPBPtr; async: Boolean): 
                        OSErr;

paramBlock

A pointer to a file control block parameter block.

async

A Boolean value that specifies asynchronous (TRUE) or synchronous (FALSE) execution.

-->	ioCompletion	ProcPtr	A pointer to a completion routine.
<--	ioResult	OSErr	The result code of the function.
<->	ioNamePtr	StringPtr	A pointer to a pathname.
-->	ioVRefNum	Integer	A volume specification.
<->	ioRefNum	Integer	The file reference number.
-->	ioFCBIndx	Integer	An index.
<--	ioFCBFlNm	LongInt	The file ID.
<--	ioFCBFlags	Integer	File status flags.
<--	ioFCBStBlk	Integer	The first allocation block of the file.
<--	ioFCBEOF	LongInt	The logical end-of-file.
<--	ioFCBPLen	LongInt	The physical end-of-file.
<--	ioFCBCrPs	LongInt	The position of the file mark.
<--	ioFCBVRefNum	Integer	The volume reference number.
<--	ioFCBClpSiz	LongInt	The file clump size.
<--	ioFCBParID	LongInt	The parent directory ID.

DESCRIPTION

The PBGetFCBInfo function returns information about the specified open file. If the value of ioFCBIndx is positive, the File Manager returns information about the file whose index in the FCB buffer is ioFCBIndx and that is located on the volume specified by ioVRefNum (which may contain a drive number, volume reference number, or working directory reference number). If the value of ioVRefNum is 0, all open files are indexed; otherwise, only open files on the specified volume are indexed.

If the value of ioFCBIndx is 0, the File Manager returns information about the file whose file reference number is specified by the ioRefNum field. If the value of ioFCBIndx is positive, the ioRefNum field is ignored on input and contains the file reference number on output.

If PBGetFCBInfo executes successfully, the ioNamePtr field contains the name of the specified open file. You should pass a pointer to a Str31 value if you want that name returned. If you pass NIL in the ioNamePtr field, no filename is returned.

The ioFCBFlags field returns status information about the specified open file. See
"File Control Block Parameter Blocks" beginning on page 2-107 for a description of
the meaning of the bits in this field.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for PBGetFCBInfo are

Trap macro	Selector
_HFSDispatch	$0008

RESULT CODES

noErr	0	No error
nsvErr	-35	Specified volume doesn't exist
fnOpnErr	-38	File not open
rfNumErr	-51	Reference number specifies nonexistent access path