2014-09-24 Paul Eggert <eggert@cs.ucla.edu>
+ Avoid signed integer overflow when converting Time to ptrdiff_t.
+ * keyboard.c (INPUT_EVENT_POS_MAX, INPUT_EVENT_POS_MIN):
+ New macros.
+ (position_to_Time, Time_to_position): New functions.
+ (gen_help_event, kbd_buffer_get_event): Use them.
+ * systime.h (Time) [emacs && !HAVE_X_WINDOWS]:
+ Go back to plain 'unsigned long', so that 'Time' is the same
+ for both X and non-X builds; this is less likely to cause surprise.
+ * termhooks.h: Remove compile-time check that Time and ptrdiff_t
+ are the same size; this is no longer required.
+
* keyboard.c (make_lispy_event): Avoid unnecessary tests
of bit 28 and of whether an unsigned value is negative.
This simplifies the code a bit, and pacifies clang 3.4.
}
}
+/* Limit help event positions to this range, to avoid overflow problems. */
+#define INPUT_EVENT_POS_MAX \
+ ((ptrdiff_t) min (PTRDIFF_MAX, min (TYPE_MAXIMUM (Time) / 2, \
+ MOST_POSITIVE_FIXNUM)))
+#define INPUT_EVENT_POS_MIN (-1 - INPUT_EVENT_POS_MAX)
+
+/* Return a Time that encodes position POS. POS must be in range. */
+
+static Time
+position_to_Time (ptrdiff_t pos)
+{
+ eassert (INPUT_EVENT_POS_MIN <= pos && pos <= INPUT_EVENT_POS_MAX);
+ return pos;
+}
+
+/* Return the position that ENCODED_POS encodes.
+ Avoid signed integer overflow. */
+
+static ptrdiff_t
+Time_to_position (Time encoded_pos)
+{
+ if (encoded_pos <= INPUT_EVENT_POS_MAX)
+ return encoded_pos;
+ Time encoded_pos_min = INPUT_EVENT_POS_MIN;
+ eassert (encoded_pos_min <= encoded_pos);
+ ptrdiff_t notpos = -1 - encoded_pos;
+ return -1 - notpos;
+}
/* Generate a HELP_EVENT input_event and store it in the keyboard
buffer.
event.arg = object;
event.x = WINDOWP (window) ? window : frame;
event.y = help;
- event.timestamp = pos;
+ event.timestamp = position_to_Time (pos);
kbd_buffer_store_event (&event);
}
frame = event->frame_or_window;
object = event->arg;
- position = make_number (event->timestamp);
+ position = make_number (Time_to_position (event->timestamp));
window = event->x;
help = event->y;
clear_event (event);
Lisp_Object arg;
};
-/* To make sure we don't break HELP_EVENT. */
-verify (sizeof (Time) == sizeof (ptrdiff_t));
-
#define EVENT_INIT(event) memset (&(event), 0, sizeof (struct input_event))
/* Bits in the modifiers member of the input_event structure.