PBGetFPosSync

PBGetFPos Query current position of an open file's file mark

#include <Files.h> File Manager (PBxxx)

OSErr PBGetFPos(pb, async );

ParmBlkPtr pb ; address of a 50-byte IOParam structure

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

returns Error Code; 0=no error

PBGetFPos obtains the current value of an open file's mark.

pb is the address of a 50-byte IOParam structure. The relevant fields

are:

Out-In Name Type Size Offset Description

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

-> ioRefNum short 2 24 File reference number

<- ioResult OSErr 2 16 Error Code (0=no error, 1=not done yet)

<- ioReqCount long 4 36 Gets set to 0

<- ioActCount long 4 40 Gets set to 0

<- ioPosMode short 2 44 Gets set to 0

<- ioPosOffset long 4 46 Receives file mark (bytes from start of file)

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

fnOpnErr (-38) File not open

gfpErr (-52) Get file position error

ioErr (-36) I/O error

rfNumErr (-51) Bad ioRefNum

Notes: After each read or write operation, the current file position is returned in

ioPosOffset; so PBGetFPos may not be needed often.

If you follow this call with a call to PBGetEOF, you can compare ioMisc to

ioPosOffset to see if you are at the end-of-file.

Referenced by (1):