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Inside Macintosh: Files /

Chapter 2 - File Manager / File Manager Reference

High-Level File Access Routines / Allocating File Blocks

Allocate

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

FUNCTION Allocate (refNum: Integer; VAR count: LongInt): OSErr;

refNum

The file reference number of an open file.

count

On input, the number of additional bytes to allocate to the file; on output, the number of bytes actually allocated, rounded up to the nearest multiple of the allocation block size.

DESCRIPTION

The Allocate function adds the specified number of bytes to the specified file and sets the physical end-of-file to 1 byte beyond the last block allocated. If there isn't enough empty space on the volume to satisfy the allocation request, Allocate allocates the rest of the space on the volume and returns dskFulErr as its function result.

The Allocate function always attempts to allocate contiguous blocks. If the total number of requested bytes is unavailable, Allocate allocates whatever space, contiguous or not, is available. To force the allocation of the entire requested space as a contiguous piece, call AllocContig instead.

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