[OLE #94] Correctly marshal NULL ppUnk refptrs in NdrPointerMarshall
Robert Shearman
rob at codeweavers.com
Mon Jun 6 11:11:36 CDT 2005
Mike Hearn wrote:
>On Mon, 2005-06-06 at 10:26 -0500, Robert Shearman wrote:
>
>
>>> switch (type) {
>>>- case RPC_FC_RP: /* ref pointer (always non-null) */
>>>-#if 0 /* this causes problems for InstallShield so is disabled - we
>>>
>>>
>>need more tests */
>>
>>
>>>- if (!Pointer)
>>>- RpcRaiseException(RPC_X_NULL_REF_POINTER);
>>>-#endif
>>>+ case RPC_FC_RP: /* ref pointer (always non-null but may point to
>>>
>>>
>>null) */
>>
>>
>>> break;
>>> case RPC_FC_UP: /* unique pointer */
>>> case RPC_FC_OP: /* object pointer - same as unique here */
>>>
>>>
>>>
>>>
>>>
>>This looks wrong. A ref pointer shouldn't be treated as a unique
>>pointer in any circumstances AFAIK. I'll add this case to my mini test
>>suite to confirm or deny this hypothesis.
>>
>>
>
>This is wire-sizing, the full code is:
>
> switch (type) {
> case RPC_FC_RP:
> case RPC_FC_OP:
> case RPC_FC_UP:
> pStubMsg->BufferLength += 4;
> /* NULL pointer has no further representation */
> if (!Pointer)
> return;
> break;
> case RPC_FC_FP:
> default:
> FIXME("unhandled ptr type=%02x\n", type);
> RpcRaiseException(RPC_X_BAD_STUB_DATA);
> }
>
> m = NdrBufferSizer[*desc & NDR_TABLE_MASK];
> if (m) m(pStubMsg, Pointer, desc);
> else FIXME("no buffersizer for data type=%02x\n", *desc);
>
>In this case, we need to reserve space for a refptr on the wire to be
>able to tell the difference between NULL and non-NULL. So it reserves 4
>bytes in the buffer.
>
>
Exactly. A refptr shouldn't have those extra 4 bytes because it should
never be NULL. I would be very surprised if Microsoft have chosen to be
inconsistent here.
--
Rob Shearman
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