oleaut - SysAllocString/SysFreeString

[Markus Stockhausen]

Hi,

maybe this topic has discussed before but I did not find any threads in
the devel mailing list for the last months. Additionally i followed wine
development for only a few weeks. So here we go ...

oleaut.c in native Windows has some type of "heap reusage" when working
with strings. This can be unconvered when placing debug messages into
IMalloc_xxx functions. A sequence of SysAllocString, SysFreeString will
show something like that:

Alloc
  olemalloc:IMalloc_fnAlloc (0x7ec47df8, 16) - addr is 0x12a1b8
Free
  olemalloc:IMalloc_fnGetSize (0x12a1b8) - 16
Alloc
  nothing
Free
  olemalloc:IMalloc_fnGetSize (0x12a1b8) - 16

When exiting the program one can see a message like this

olemalloc:IMalloc_fnFree (0x7ec47df8, 0x12a1b8)

In Wine the heap will be released immediately. Why sould that be of any
concern you may ask. This behaviour makes some buggy applications run
with native oleaut32 (see bug 12460). In this case the application
copies the contents of a string directly after it has been freed. Wine
corrupts the heap in between and the application will crash.

My question is: Should this behaviour declared as "application is buggy
& will not be fixed" or has a patch a chance to find its way into git?
An idea would be an deferred free like this.

- TlsAlloc on entry of dll.

- SysFreeString
  TlsGetValue for last address
  if value is set FreeHeap(address)
  TlsSetValue for current address

- on exit of dll do some cleanup (heap & Tls)

Of course this behaviour is far away from the oleaut implementation and
will consume some more CPU cycles.

Thanks for your feedback in inadvance.

Markus