b20.1: fhandler_serial.cc: stuck error: fAbortOnError & ClearCommError is never called

[Stas Maximov]

Description:

If parity error INPCK & !IGNPAR and parity error happens on serial port
(replugged cables on the fly, while app holds the port's descriptor),
all further read/write calls fail with EACCES.

Explanation:

fhandler_serial::tcsetattr sets Win32 DCB::fAbortOnError that means that
any error condition on the port (and parity is one of them) will abort
IO operation ReadFile/WriteFile with ERROR_OPERATION_ABORTED(995) and
all further IO operations will fail with the same error till
ClearCommError is called.

fhandler_serial::tcsetattr sets DCB::fAbortOnError, but never calls
ClearCommError to clear the error condition.

Another thing is that fhandler_serial::open does not set
DCB::fAbortOnError, so the behavior is different when you use default
settings and try to set the default settings using tcsetattr.

Solution:

1. Make fhandler_serial::open to be consistent with
fhandler_serial::tcsetattr, i.e. both of them will set
DCB::fAbortOnError.

2. Modify fhandler_serial::raw_read/raw_write that will basically use
fhandler_base::raw_read/raw_write, but in case ERROR_OPERATION_ABORTED
happens, they will proceed according to termios settings on the device.

3. Add termios as a member to fhandler_serial. Check if fhandle_union is
still fhsndle_console after that!

Question:

I am willing to fix it. Do I have to subscribe to cygwin-developers
list?

Stas.



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