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

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

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.

Tested on aarch64-linux.
---
 gdb/python/lib/gdb/dap/io.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gdb/python/lib/gdb/dap/io.py b/gdb/python/lib/gdb/dap/io.py
index 4edd504c727..e5547bd1072 100644
--- a/gdb/python/lib/gdb/dap/io.py
+++ b/gdb/python/lib/gdb/dap/io.py
@@ -77,6 +77,9 @@ def start_json_writer(stream, queue):
             header_bytes = header.encode("ASCII")
             stream.write(header_bytes)
             stream.write(body_bytes)
-            stream.flush()
+            try:
+                stream.flush()
+            except OSError:
+                break
 
     start_thread("JSON writer", _json_writer)
-- 
2.35.3