[Bug 6895] New: Wrong ReadFile timeout reading from serial (COM) port

[Wine Bugs]

http://bugs.winehq.org/show_bug.cgi?id=6895

Summary: Wrong ReadFile timeout reading from serial (COM) port
           Product: Wine
           Version: 0.9.27.
          Platform: PC
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: wine-kernel
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]

In Windows, there is a special combination of COMMTIMEOUTS (SetCommTimeouts
function) settings for reading from serial devices:

if an application sets the elements ReadIntervalTimeout and
ReadTotalTimeoutMultiplier to MAXDWORD and sets ReadTotalTimeoutConstant to a
value greater than zero and less than MAXDWORD, one of the following occurs when
the ReadFile function is called:

1. If there are characters in the input buffer, ReadFile returns immediately
with the characters in the buffer.
2. If there are no characters in the input buffer, ReadFile waits until a
character arrives and then returns immediately.
3. If no characters arrive within the time specified by
ReadTotalTimeoutConstant, ReadFile times out.

This does not work correctly in wine (version 0.9.27), the ReadFile always waits
the timeout specified by ReadTotalTimeoutConstant in case 1 and 2 above if the
number of characters in the input buffer is less than the number of characters
expected.

This can result in a very slow communication in applications which use this feature.