> Is recPtr in DmWrite() a valid pointer?
Yes, I know that it is because if I change the FldGetTextPtr call to
a combination of FldGetTextHandle and MemHandleLock, then
the problem goes away.
The below info might be useful, thanks for finding it...
-Gabe
Palm Creations
>That said, I found some old mail from Ken Krugler regarding FldGetTextPtr():
>
>>>>
>If you've got a typical editable field, then the pointer returned by
>FldGetTextPtr should be valid until:
>
>a. You make another call to the field code. Some of the Field APIs
>would seem safe to call, but given the dynamic nature of the rom code,
>you're better off not relying on the pointer staying valid.
>
>b. You make a call to something that in turn calls a field routine.
>For example, the form code will call the field code to dispose of the
>handle when the form is being tossed.
>
>c. The field's text handle gets munged by you or some other routine
>which knows about it. Obviously if you mess with the handle then all bets
>are off.
>
>Note that if the field is empty, then the call to FldGetTextPtr can return
>null if the text handle never had to be allocated.
><<<
>
>Michael Yam
>Y Technology, Inc.
>[EMAIL PROTECTED]
>
>
>-----Original Message-----
>From: Gabe Dalbec <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
>Date: Friday, May 07, 1999 1:36 AM
>Subject: FldGetTextPtr - not a good pointer?
>
>
>
>I am seeing some strange results from the Emulator when I use
>FldGetTextPtr. The following code snip shows this:
>
>{
> CharPtr fldVal;
> Char saveVal[100];
>
> fldVal = FldGetTextPtr(fieldP);
> if(fldVal)
> {
> int len = StrLen(fldVal);
> if(len < 100)
> {
> StrCopy(saveVal, fldVal);
> DmWrite(recPtr, 0, fldVal, len);
> }
> }
>}
>
>When this runs, the Emulator reports an error on the DmWrite, saying
>that I "have just read directly from memory manager data structures".
>Why does it report this on the DmWrite but not on the StrLen or the
>ScrCopy, both of which access the same fldVal. If I change the code to
>use FldGetTextHandle and MemHandleLock instead of going straight to the
>pointer with FldGetTextPtr, then it works fine, no complaints from the
>emulator. Either way runs fine on the device.
>
>Is this a bug in the emulator or maybe the OS, or am I missing
>something?
>
>Thanks,
>-Gabe
>Palm Creations
