> Is a free handle an invalid handle? A freed handle?
It's the latter. It's a handle that has been passed to MemHandleFree.
> Doesn't DmGetRecord() return a handle?
It does it if has one to give. But imagine the following (buggy) code:
recordH = DmGetRecord(dbToUse, indexToGet);
MemHandleFree (recordH); /* Oops! Need to call DmDetachRecord first! */
/* lot's of other stuff */
recordH = DmGetRecord(dbToUse, indexToGet);
if (recordH == NULL)
ErrDisplay("Can retrieve record");
recText = (Char*)MemHandleLock(recordH);
Under this scenario, the second call to DmGetRecord will return a handle to a
chunk of memory that has been freed.
-- Keith
[EMAIL PROTECTED] on 07/06/2000 01:13:45 AM
Please respond to "Palm Developer Forum" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
To: "Palm Developer Forum" <[EMAIL PROTECTED]>
cc: (Keith Rollin/US/PALM)
Subject: Free handle, what is it?
Hi all,
I need help debugging this little code snippet.
/*global*/ DmOpenRef dbToUse;
void static MyFunction();
MemHandle recordH;
Char *recText;
{
recordH = DmGetRecord(dbToUse, indexToGet);
if (recordH == NULL)
ErrDisplay("Can retrieve record");
recText = (Char*)MemHandleLock(recordH);
}
dbToUse has been opened by
DmOpenDatabaseByTypeCreator(MenuProtoUserDBType, CreatorID, mode);
elsewhere. I'm pretty sure the dbToUse is opened for reading, I've even
checked it with
error = DmOpenDatabaseInfo(dbToUse, &dbID, &openCount, &mode, &cardNo,
&resDB);
ErrFatalDisplayIf(error, "Database not opened");
The problem is whenever I try to lock recordH with
MemHandleLock(recordH); I get "MemoryMgrNew.c, Line:4177, Free handle"
on the log window.
recText would then point to some invalid address space.
Is a free handle an invalid handle? A freed handle? Doesn't
DmGetRecord() return a handle? Or do I have to explicitly use a
recordH=MemHandleNew(x)? But I wouldn't know how much memory to assign
for DmGetRecord.
Any help would be greatly appreciated. Thanks!!
Wee Meng CHONG
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