Commit 203a9eb0 authored by Paul Eggert's avatar Paul Eggert

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.
parent 0e176389
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.
......
......@@ -3729,6 +3729,34 @@ kbd_buffer_unget_event (register struct input_event *event)
}
}
/* 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.
......@@ -3752,7 +3780,7 @@ gen_help_event (Lisp_Object help, Lisp_Object frame, Lisp_Object window,
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);
}
......@@ -4084,7 +4112,7 @@ kbd_buffer_get_event (KBOARD **kbp,
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);
......
......@@ -19,7 +19,6 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#ifndef EMACS_SYSTIME_H
#define EMACS_SYSTIME_H
#include <sys/types.h>
#include <timespec.h>
INLINE_HEADER_BEGIN
......@@ -28,7 +27,7 @@ INLINE_HEADER_BEGIN
# ifdef HAVE_X_WINDOWS
# include <X11/X.h>
# else
typedef size_t Time;
typedef unsigned long Time;
# endif
#endif
......
......@@ -288,9 +288,6 @@ struct input_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.
......
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