[PATCH 5/5] Python unwinder sniffer: PyExc_KeyboardInterrupt -> Quit
Pedro Alves
palves@redhat.com
Mon Nov 6 23:22:00 GMT 2017
If you happen to press Ctrl-C while GDB is running the Python unwinder
machinery, the Ctrl-C is swallowed by the Python unwinder machinery.
For example, with:
break foo
commands
> c
> end
and
while (1)
foo ();
and then let the inferior hit "foo" repeatedly, sometimes Ctrl-C
results in:
~~~
23 usleep (100);
Breakpoint 2, foo () at gdb.base/bp-cmds-continue-ctrl-c.c:23
23 usleep (100);
^C
Breakpoint 2, Python Exception <class 'KeyboardInterrupt'> <class 'KeyboardInterrupt'>:
foo () at gdb.base/bp-cmds-continue-ctrl-c.c:23
23 usleep (100);
Breakpoint 2, foo () at gdb.base/bp-cmds-continue-ctrl-c.c:23
23 usleep (100);
Breakpoint 2, foo () at gdb.base/bp-cmds-continue-ctrl-c.c:23
23 usleep (100);
~~~
Notice the Python exception above. The interesting thing here is that
GDB continues as if nothing happened, doesn't really stop and give
back control to the user. Instead, the Ctrl-C aborted the Python
unwinder sniffer and GDB moved on to just use another unwinder.
Fix this by translating a PyExc_KeyboardInterrupt back into a Quit
exception once back in GDB.
This was exposed by the new gdb.base/bp-cmds-continue-ctrl-c.exp
testcase added later in the series.
gdb/ChangeLog:
yyyy-mm-dd Pedro Alves <palves@redhat.com>
* python/py-unwind.c (pyuw_sniffer): Translate
PyExc_KeyboardInterrupt to a GDB Quit exception.
---
gdb/python/py-unwind.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/gdb/python/py-unwind.c b/gdb/python/py-unwind.c
index acfce7d..b578373 100644
--- a/gdb/python/py-unwind.c
+++ b/gdb/python/py-unwind.c
@@ -539,6 +539,13 @@ pyuw_sniffer (const struct frame_unwind *self, struct frame_info *this_frame,
pyo_pending_frame.get (), NULL));
if (pyo_unwind_info == NULL)
{
+ /* If the unwinder is cancelled due to a Ctrl-C, then propagate
+ the Ctrl-C as a GDB exception instead of swallowing it. */
+ if (PyErr_ExceptionMatches (PyExc_KeyboardInterrupt))
+ {
+ PyErr_Clear ();
+ quit ();
+ }
gdbpy_print_stack ();
return 0;
}
--
2.5.5
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