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Inside Macintosh: Files /

Chapter 2 - File Manager / File Manager Reference

Shared Environment Routines / Locking and Unlocking File Ranges

PBUnlockRange

You can use the PBUnlockRange function to unlock a portion of a file that was previously locked by a call to PBLockRange.

FUNCTION PBUnlockRange (paramBlock: ParmBlkPtr; async: Boolean): 
                        OSErr;

paramBlock

A pointer to a basic File Manager 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.
-->	ioRefNum	Integer	A file reference number.
-->	ioReqCount	LongInt	The number of bytes in the range.
-->	ioPosMode	Integer	The positioning mode.
-->	ioPosOffset	LongInt	The positioning offset.

DESCRIPTION

The PBUnlockRange function unlocks a portion of a file that you locked with PBLockRange. You specify the range by filling in the ioReqCount, ioPosMode,
and ioPosOffset fields as described in the preceding discussion of PBLockRange. The range of bytes to be unlocked must be the exact same range locked by a previous
call to PBLockRange.

If for some reason you need to unlock a range whose beginning or length is unknown, you can simply close the file. When a file is closed, all locked ranges held by the user
are unlocked.

SPECIAL CONSIDERATIONS

The PBUnlockRange function does nothing if the file specified in the ioRefNum field is open with shared read/write permission but is not located on a remote server volume or is not located under a share point on a local volume.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for PBUnlockRange are

Trap macro	Selector
_HFSDispatch	$0011

RESULT CODES

noErr	0	No error
ioErr	-36	I/O error
fnOpnErr	-38	File not open
eofErr	-39	Logical end-of-file reached
paramErr	-50	Negative ioReqCount
rfNumErr	-51	Bad reference number
extFSErr	-58	External file system
volGoneErr	-124	Server volume has been disconnected
afpRangeNotLocked	-5020	Specified range was not locked