FSpOpenDF

Create an access path to the data fork of a file

#include <Files.h> File Manager

OSErr FSpOpenDF(spec, permission , refNum);

FSSpec *spec; a pointer to n FSSpec record

char permission ; permission level

short *refNum ; points to a path reference number

returns Error Code; 0=no error

FSpOpenDF creates an access path to the data fork of a file. It is the FSSpec

version of the new function HOpenDF, which replaces the functions FSOpen

and HOpen. The difference is that HOpenDF opens only the data fork of a file;

FSOpen and HOpen can open either a driver or the data fork of a file. Using

FSpOpenDF eliminates the ambiguity and ensures that you can open even a

file whose name begins with a period (.)

spec is a pointer to an FSSpec record specifying the file to be opened.

permission specifies the kind of access path permission you want. In most

cases, you can simply set the permission parameter to fsCurPerm.

See the notes section below for addtional information on the

permission parameter.

refNum is a pointer to the path reference number. FSpOpenDF opens the

data fork and places the path reference number in the refNum

parameter.

Returns: an operating system Error Code. It will be one of:

noErr (0) No error

bdNamErr (-37) Bad name

extFSErr (-58) External file system

ioErr (-36) I/O error

nsvErr (-35) No such volume

opWrErr (-49) File already open for writing

tmfoErr (-42) Too many files open

Notes: FSpOpenDF takes a permission parameter

In most cases, you can simply set the permission parameter to fsCurPerm.

Some applications request fsRdWrPerm, to ensure that they can both read

and write to a file. The constants that can be passed in this field are the

following:

fsCurPerm exclusive read/write permission if it is available;

otherwise, exclusive read, if that is available

fsRdPerm exclusive read permission

fsWrPerm exclusive write permission

fsRdWrPerm exclusive read/write permission

fsRdWrShPerm shared read/write permission

In shared environments, permission requests are translated into the

"deny-mode" permissions defined by AppleShare.

Referenced by (11):