Throw a "quit" on a KeyboardException in py-framefilter.c

If a C-c comes while the Python code for a frame filter is running, it
will be turned into a Python KeyboardException.  It seems good for
this to be treated like a GDB quit, so this patch changes
py-framefilter.c to notice this situation and call throw_quit in this
case.

gdb/ChangeLog
2018-03-26  Tom Tromey  <tom@tromey.com>

	* python/py-framefilter.c (throw_quit_or_print_exception): New
	function.
	(gdbpy_apply_frame_filter): Use it.

gdb/testsuite/ChangeLog
2018-03-26  Tom Tromey  <tom@tromey.com>

	* gdb.python/py-framefilter.exp: Add test for KeyboardInterrupt.
	* gdb.python/py-framefilter.py (name_error): New global.
	(ErrorInName.function): Use name_error.

gdb/ChangeLog

@@ -1,3 +1,9 @@
+2018-03-26  Tom Tromey  <tom@tromey.com>
+
+	* python/py-framefilter.c (throw_quit_or_print_exception): New
+	function.
+	(gdbpy_apply_frame_filter): Use it.
+
 2018-03-26  Tom Tromey  <tom@tromey.com>
 
 	PR cli/17716:

gdb/python/py-framefilter.c

@@ -1305,6 +1305,21 @@ bootstrap_python_frame_filters (struct frame_info *frame,
     return iterable.release ();
 }
 
+/* A helper function that will either print an exception or, if it is
+   a KeyboardException, throw a quit.  This can only be called when
+   the Python exception is set.  */
+
+static void
+throw_quit_or_print_exception ()
+{
+  if (PyErr_ExceptionMatches (PyExc_KeyboardInterrupt))
+    {
+      PyErr_Clear ();
+      throw_quit ("Quit");
+    }
+  gdbpy_print_stack ();
+}
+
 /*  This is the only publicly exported function in this file.  FRAME
     is the source frame to start frame-filter invocation.  FLAGS is an
     integer holding the flags for printing.  The following elements of
@@ -1375,7 +1390,7 @@ gdbpy_apply_frame_filter (const struct extension_language_defn *extlang,
 	 initialization error.  This return code will trigger a
 	 default backtrace.  */
 
-      gdbpy_print_stack ();
+      throw_quit_or_print_exception ();
       return EXT_LANG_BT_NO_FILTERS;
     }
 
@@ -1398,7 +1413,7 @@ gdbpy_apply_frame_filter (const struct extension_language_defn *extlang,
 	{
 	  if (PyErr_Occurred ())
 	    {
-	      gdbpy_print_stack ();
+	      throw_quit_or_print_exception ();
 	      return EXT_LANG_BT_ERROR;
 	    }
 	  break;
@@ -1423,7 +1438,7 @@ gdbpy_apply_frame_filter (const struct extension_language_defn *extlang,
       /* Do not exit on error printing a single frame.  Print the
 	 error and continue with other frames.  */
       if (success == EXT_LANG_BT_ERROR)
-	gdbpy_print_stack ();
+	throw_quit_or_print_exception ();
     }
 
   return success;

gdb/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2018-03-26  Tom Tromey  <tom@tromey.com>
+
+	* gdb.python/py-framefilter.exp: Add test for KeyboardInterrupt.
+	* gdb.python/py-framefilter.py (name_error): New global.
+	(ErrorInName.function): Use name_error.
+
 2018-03-26  Tom Tromey  <tom@tromey.com>
 
 	PR backtrace/15582:

gdb/testsuite/gdb.python/py-framefilter.exp

@@ -213,6 +213,12 @@ gdb_test_multiple "bt 1" $test {
     }
 }
 
+# Now verify that we can see a quit.
+gdb_test_no_output "python name_error = KeyboardInterrupt" \
+    "Change ErrorFilter to throw KeyboardInterrupt"
+gdb_test "bt 1" "Quit" "bt 1 with KeyboardInterrupt"
+
+
 # Test with no debuginfo
 
 # We cannot use prepare_for_testing as we have to set the safe-patch

gdb/testsuite/gdb.python/py-framefilter.py

@@ -134,13 +134,17 @@ class FrameElider ():
     def filter (self, frame_iter):
         return ElidingIterator (frame_iter)
 
+# This is here so the test can change the kind of error that is
+# thrown.
+name_error = RuntimeError
+
 # A simple decorator that gives an error when computing the function.
 class ErrorInName(FrameDecorator):
     def __init__(self, frame):
         FrameDecorator.__init__(self, frame)
 
     def function(self):
-        raise RuntimeError('whoops')
+        raise name_error('whoops')
 
 # A filter that supplies buggy frames.  Disabled by default.
 class ErrorFilter():