All Databases Inside Mac - Basic Toolbox

PBHOpenDFSync

PBHOpenDF

Open the data fork of a file on a hierarchical volume

#include <Files.h> File Manager

OSErr PBHOpenDF(pb, async );

HParmBlkPtr pb ; address of an ParamBlockRec record

Boolean async ; 0=await completion; 1=immediate return

returns Error Code; 0=no error

Use the PBHOpenDF function to open the data fork of a file on a hierarchical

volume. PBHOpenDF replaces PBHOpen , which can open either a driver or

the data fork of a file.

pb is a pointer to a IOParam structure.The relevant fields are as

follows:

Out-InName Type Size Offset Description

Æ ioCompletion ProcPtr 4 12 Completion routine address (if async =TRUE)

¨ ioResult short 2 16 Error Code (0=no error, 1=not done yet)

Æ ioNamePtr StringPtr 4 18 pointer to file or directory name

Æ ioVRefNum short 2 22 Volume reference

¨ ioRefNum short 2 24 access path number

Æ ioPermssn char 1 27 permission

Æ ioDirID long 4 48 parent directory ID

async is a Boolean value. Use FALSE for normal (synchronous) operation

or TRUE to enqueue the request and resume control immediately. See

Async I/O.

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

noErr (0) No error

nsvErr (-35) Volume not found

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

extFSErr (-58) External file system

dirNFErr (-120) Directory not found

Notes: PBHOpenDF creates an access path to the data fork of a file. It is almost

identical to PBHOpen . The difference is that PBHOpen can open both files

and drivers, but PBHOpenDF can open only files. Using PBHOpenDF

instead of PBHOpen when your application is opening a file pr events

naming conflicts or ambiguities and ensures that your application can open

files whose names begin with a period (.).

PBHOpenDF 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.