Re: [RFC 3/3] [gdb/dap] Ignore OSError on stream.flush in JSON writer

[Tom de Vries <tdevries@suse.de>]

On 2/7/24 10:02, Tom de Vries wrote:
> Due to the previous two fixes, I can now run test-case gdb.dap/eof.exp without
> coredumps happening.
> 
> However, I do run into:
> ...
> FAIL: gdb.dap/eof.exp: exceptions in log file
> ...
> due to:
> ...
> JSON writer: caught exception: err=OSError(5, 'Input/output error'),
>    type(err)=<class 'OSError'>
> Traceback (most recent call last):
>    File "python/gdb/dap/startup.py", line 72, in thread_wrapper
>      target(*args)
>    File "python/gdb/dap/io.py", line 80, in _json_writer
>      stream.flush()
> OSError: [Errno 5] Input/output error
> ...
> 
> I can image that the stream.flush would throw an OSError if it races with the
> gdb main thread handling a SIGHUP and finalizing python in the process.
> 
> Handle this is in the simplest way I can think of: ignore the OSError, and
> terminate the DAP thread.

I just found that the JSON reader thread does:
...
     except OSError:
         # Reading can also possibly throw an exception.  Treat this as 

         # EOF. 

         log_stack(LogLevel.FULL)
         return None
...

If we however threat this is in the JSON writer thread the same way, we 
get a FAIL from dap_check_log_file, because it checks for ^Traceback, 
which is generated by the log_stack.

Thanks,
- Tom