[gdb] Handle SIGTERM in run_events

While reviewing "catch (...)" uses I came across:
...
  for (auto &item : local)
    {
      try
	{
	  item ();
	}
      catch (...)
	{
	  /* Ignore exceptions in the callback.  */
	}
    }
...

This means that when an item throws a gdb_exception_forced_quit,
the exception is ignored and following items are executed.

Fix this by handling gdb_exception_forced_quit explicity, and immediately
rethrowing it.

I wondered about ^C, and couldn't decide whether current behaviour is ok, so
I left this alone, but I made the issue explicit in the source code.

As for the "catch (...)", I think that it should let a non-gdb_exception
propagate, so I've narrowed it to "catch (const gdb_exception &)".

My rationale for this is as follows.

There seem to be a few ways that "catch (...)" is allowed in gdb:
- clean-up and rethrow (basically the SCOPE_EXIT pattern)
- catch and handle an exception from a call into an external c++ library

Since we're dealing with neither of those here, we remove the "catch (...)".

Tested on aarch64-linux.

Approved-By: Tom Tromey <tom@tromey.com>

diff --git a/gdb/run-on-main-thread.c b/gdb/run-on-main-thread.c
index e30dabaff03267b6d10c2f64d2ac16bc921adf17..a6213d4d85eea88111bd528f212c4d7596578121 100644 (file)
--- a/gdb/run-on-main-thread.c
+++ b/gdb/run-on-main-thread.c
@@ -74,7 +74,20 @@ run_events (int error, gdb_client_data client_data)
        {
          item ();
        }
-      catch (...)
+      catch (const gdb_exception_forced_quit &e)
+       {
+         /* GDB is terminating, so:
+            - make sure this is propagated, and
+            - no need to keep running things, so propagate immediately.  */
+         throw;
+       }
+      catch (const gdb_exception_quit &e)
+       {
+         /* Should cancelation of a runnable event cancel the execution of
+            the following one?  The answer is not clear, so keep doing what
+            we've done sofar: ignore this exception.  */
+       }
+      catch (const gdb_exception &)
        {
          /* Ignore exceptions in the callback.  */
        }