Legacy Document

Inside Macintosh: Files /

Chapter 2 - File Manager / File Manager Reference

Low-Level HFS Routines / Opening Files

PBHOpenRF

You can use the PBHOpenRF function to open the resource fork of file.

FUNCTION PBHOpenRF (paramBlock: HParmBlkPtr; async: Boolean): 
                     OSErr;

paramBlock

A pointer to a basic HFS 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	A file reference number.
-->	ioPermssn	SignedByte	The read/write permission.
-->	ioDirID	LongInt	A directory ID.

DESCRIPTION

The PBHOpenRF function creates an access path to the resource fork of a file and returns a file reference number in the ioRefNum field.

SPECIAL CONSIDERATIONS

Generally your application should use Resource Manager routines rather than File Manager routines to access a file's resource fork. The PBHOpenRF function does not read the resource map into memory and is generally useful only for applications (such as utilities that copy files) that need block-level access to a resource fork. In particular, you should not use the resource fork of a file to hold nonresource data. Many parts of the system software assume that a resource fork always contains resource data.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro for PBHOpenRF is _HOpenRF.

RESULT CODES

noErr	0	No error
nsvErr	-35	No such volume
ioErr	-36	I/O error
bdNamErr	-37	Bad filename
tmfoErr	-42	Too many files open
fnfErr	-43	File not found
opWrErr	-49	File already open for writing
permErr	-54	Attempt to open locked file for writing
dirNFErr	-120	Directory not found or incomplete pathname
afpAccessDenied	-5000	User does not have the correct access to the file