Legacy Document

Inside Macintosh: Files /

Chapter 2 - File Manager / File Manager Reference

High-Level HFS Routines / Opening Files

HOpen

You can use the HOpen function to open the data fork of a file. Because HOpen also opens devices, it's safer to use the HOpenDF function instead.

FUNCTION HOpen (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 HOpen function creates an access path to the data fork of the specified file. A file reference number for that file is returned in the refNum parameter.

WARNING

If you use HOpen to try to open a file whose name begins with a period, you might mistakenly open a driver instead; subsequent attempts to write data might corrupt data on the target device. To avoid these problems, you should always use HOpenDF instead of HOpen.

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