[PATCH] winhttp: Process end of read data before sending callback in read_data().

[Paul Gofman]

On 10/15/21 13:04, Hans Leidekker wrote:
> On Thu, 2021-10-14 at 18:17 +0300, Paul Gofman wrote:
>> Signed-off-by: Paul Gofman <pgofman at codeweavers.com>
>> ---
>>      The read completion callback may call WineHttpReadData(). Which may either run
>>      synchronously (if the data is available and recursion depth limit is not reached)
>>      or queued to thread pool. Fallout76 always proceeds with last WinHttpReadData of
>>      size 0 with recursion limit reached, and finished_reading() is racing between the
>>      (synchronous) call which has read the last portion of data and the queued
>>      WinHttpReadData called with zero size sometimes causing a crash in cache_connection
>>      which may be called with NULL connection in this case.
>>
>>   dlls/winhttp/request.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/dlls/winhttp/request.c b/dlls/winhttp/request.c
>> index 2c064bb767b..a9c65d15fa8 100644
>> --- a/dlls/winhttp/request.c
>> +++ b/dlls/winhttp/request.c
>> @@ -1850,6 +1850,7 @@ static DWORD read_data( struct request *request, void *buffer, DWORD size, DWORD
>>   
>>
>>   done:
>>       TRACE( "retrieved %u bytes (%u/%u)\n", bytes_read, request->content_read, request->content_length );
>> +    if (end_of_read_data( request )) finished_reading( request );
>>       if (async)
>>       {
>>           if (!ret) send_callback( &request->hdr, WINHTTP_CALLBACK_STATUS_READ_COMPLETE, buffer, bytes_read );
>> @@ -1863,7 +1864,6 @@ done:
>>       }
>>   
>>
>>       if (!ret && read) *read = bytes_read;
>> -    if (end_of_read_data( request )) finished_reading( request );
>>       return ret;
>>   }
> This could use a test because it changes the order of notifications.
> When finished_reading() closes the connection
> WINHTTP_CALLBACK_STATUS_CLOSING_CONNECTION will now be sent before
> WINHTTP_CALLBACK_STATUS_READ_COMPLETE.
>
>
Yes, I thought of that but found there is already 
read_allow_close_test[] used from test_persistent_connection(). This 
test lists connection close notifications before 
WINHTTP_CALLBACK_STATUS_READ_COMPLETE (which seems to be inlined with my 
change), although these are marked with NF_ALLOW and test succeeds both 
with and without my changes. Do you think I should try to make the test 
more conclusive?