Canceling an Asynchronous File Read Operation

Hi All,

I have one requirement like, I want to issue Asychronous File Read/Write operation. Then if the request is still pending, I want o cancel that operation. This in deed should make sure that File pointer will be proper, in the sense that its still pointing to the same offset which it was before calling my Async Read/Write.

May be my code looks something like this:

_LIT( KFileName, "C:\\NewFile.txt");
RFs fileSession;
User::LeaveIfError(fileSession.Connect());
RFile file;
User::LeaveIFError(file.Open(Open(fileSession, KFileName, EFileRead | EFileShareAny));

//Get the current offset.
TInt offset = 0;
User::LeaveIfError(file.Seek(ESeekCurrent, offset));

//Read Data
TBuf8<600> readData;
TRequestStatus readStatus;
file.Read(readData, readCount, readStatus);

if(readStatus == KRequestPending)
{
/*
Now cancel the Read operation.
I dont know how to implement this part. Some one please help me.
I have tried with this code,
   TRequestStatus* sp = &readStatus;
   //User::RequestComplete(sp, KErrCancel);
   RThread().RequestComplete(sp, KErrCancel);
After this readStatus was KErrCancel, but after sometimes it changes to KErrNone as Server complets Asyn Read successfully.
*/
   TInt newOffset = 0;
   User::LeaveIfError(file.Seek(ESeekCurrent, newOffset));
   if(newOffset != offset)
      {
      //It was not properly cancelled !!!
      }
}



Now, please please..  some one help me implementing the Read Cancel, if its practically possible


Thanks a lot in advance
Girish