Legacy Document

Inside Macintosh: Files /

Chapter 2 - File Manager / File Manager Reference

High-Level HFS Routines / Opening Files

HOpenRF

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

FUNCTION HOpenRF (vRefNum: Integer; dirID: LongInt; 
                  fileName: Str255; permission: SignedByte; 
                  VAR refNum: Integer): OSErr;

vRefNum

A volume reference number, a working directory reference number, or 0 for the default volume.

dirID

A directory ID.

fileName

The name of the file.

permission

The access mode under which to open the file.

refNum

The file reference number of the opened file.

DESCRIPTION

The HOpenRF function creates an access path to the resource fork of a file. A file reference number for that file is returned in the refNum parameter.

SPECIAL CONSIDERATIONS

Generally, your application should use Resource Manager routines rather than File Manager routines to access a file's resource fork. The HOpenRF 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.

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