Hello folks,
I'm trying to intercept the insertion of a memory card and to scan its
contents. Here is what I'm doing:
1) On sysAppLaunchCmdSystemReset and sysAppLaunchCmdSyncNotify I register to
receive notifications about the sysNotifyVolumeMountedEvent event:
UInt32 PilotMain (UInt16 cmd, MemPtr cmdPBP, UInt16 launchFlags)
{
UInt16 cardNo;
LocalID dbID;
UInt32 romVersion;
switch (cmd)
{
case sysAppLaunchCmdNormalLaunch:
AppStart ();
FrmGotoForm (kMainForm);
AppEventLoop ();
AppStop ();
break;
case sysAppLaunchCmdSystemReset:
case sysAppLaunchCmdSyncNotify:
FtrGet (sysFtrCreator, sysFtrNumROMVersion, &romVersion);
if (romVersion >= version40)
SysNotifyRegister (cardNo, dbID, sysNotifyVolumeMountedEvent,
NULL, sysNotifyNormalPriority, NULL);
break;
case sysAppLaunchCmdNotify:
HandleNotification ((SysNotifyParamType *) cmdPBP);
break;
default:
break;
}
return 0;
}
2) When the notification arrives, I basically do
void HandleNotification (SysNotifyParamType *np)
{
switch (np->notifyType)
{
case sysNotifyVolumeMountedEvent:
AppStart ();
FrmGotoForm (kScanningMemoryCardForm);
AppEventLoop ();
AppStop ();
break;
default:
break;
}
}
The code is written so that it doesn't use any global or static variables. This
works fine on the Tungsten E simulator, using HostFS to simulate a card with a
directory on the PC. True, I can't "insert a card" in the simulator - but the
sysNotifyVolumeMountedEvent event is broadcast on soft reset too (makes sense -
the volume has to be mounted during reset), and when I reset the simulator, my
application is launched and it scans the card.
However, when I try it on a real device (Tungsten E), as soon as I insert a
card (or during reset, if a card is left in the slot) I get a system crash with
the memory manager complaining about a NULL pointer. I've been using a
FrmCustomAlert to display debugging messages and, interestingly, the custom
alert is flashed on the screen - but there is no waiting for the user to tap on
its button; instead I immediately get the message for the crash.
Another thing. The crash does not happen and the application scans the inserted
card properly, if the application was running at the moment when the card was
inserted.
Any hints what might be the problem? The documentation explicitly says that you
*can* use the user interface during notifications. Yet the program crashes as
if there is no current form or something. And why doesn't it crash under the
simulator? Is there anything obviuous that I might be missing?
Regards,
Vesselin
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