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Inside Macintosh: Files /

Chapter 2 - File Manager / File Manager Reference

Low-Level File Access Routines / Allocating File Blocks

PBAllocContig

You can use the PBAllocContig function to allocate additional contiguous blocks to an open file.

FUNCTION PBAllocContig (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 requested.
<--	ioActCount	LongInt	The number of bytes allocated, rounded up to the nearest multiple of the allocation block size.

DESCRIPTION

The PBAllocContig function is identical to the PBAllocate function except that if there isn't enough contiguous empty space on the volume to satisfy the allocation request, PBAllocContig does nothing and returns dskFulErr as its function result. If you want to allocate whatever space is available, even when the entire request cannot be filled by the allocation of a contiguous piece, call PBAllocate instead.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro for PBAllocContig is _AllocContig.

RESULT CODES

noErr	0	No error
dskFulErr	-34	Disk full
ioErr	-36	I/O error
fnOpnErr	-38	File not open
wPrErr	-44	Hardware volume lock
fLckdErr	-45	File is locked
vLckdErr	-46	Software volume lock
rfNumErr	-51	Bad reference number
wrPermErr	-61	Read/write permission doesn't allow writing