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Deal gracefully with up-events (Bug#19746)

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* keyboard.c (apply_modifiers_uncached, parse_solitary_modifier)
(parse_modifiers_uncached): React gracefully to "up-" modifiers:
those may easily be injected by user-level Lisp code.
(read_key_sequence): Discard unbound up-events like unbound
down-events: they are even more likely only relevant for special
purposes.

While Emacs will not produce up-events on its own currently (those are
converted to drag or click events before being converted to
Lisp-readable structures), the input queue can be made to contain them
by synthesizing events to `unread-command-events'.  Emacs should deal
consistently with such events.
This commit is contained in:
David Kastrup 2015-01-28 11:53:54 +01:00
parent b367d7fc7b
commit ad0b6dd05a
1 changed files with 24 additions and 11 deletions
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35
src/keyboard.c
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@ -6241,6 +6241,10 @@ parse_modifiers_uncached (Lisp_Object symbol, ptrdiff_t *modifier_end)
case 't':
MULTI_LETTER_MOD (triple_modifier, "triple", 6);
break;
case 'u':
MULTI_LETTER_MOD (up_modifier, "up", 2);
break;
#undef MULTI_LETTER_MOD
}
@ -6288,16 +6292,19 @@ apply_modifiers_uncached (int modifiers, char *base, int base_len, int base_len_
/* Since BASE could contain nulls, we can't use intern here; we have
to use Fintern, which expects a genuine Lisp_String, and keeps a
reference to it. */
char new_mods[sizeof "A-C-H-M-S-s-down-drag-double-triple-"];
char new_mods[sizeof "A-C-H-M-S-s-up-down-drag-double-triple-"];
int mod_len;
{
char *p = new_mods;
/* Only the event queue may use the `up' modifier; it should always
be turned into a click or drag event before presented to lisp code. */
if (modifiers & up_modifier)
emacs_abort ();
/* Mouse events should not exhibit the `up' modifier once they
leave the event queue only accessible to C code; `up' will
always be turned into a click or drag event before being
presented to lisp code. But since lisp events can be
synthesized bypassing the event queue and pushed into
`unread-command-events' or its companions, it's better to just
deal with unexpected modifier combinations. */
if (modifiers & alt_modifier) { *p++ = 'A'; *p++ = '-'; }
if (modifiers & ctrl_modifier) { *p++ = 'C'; *p++ = '-'; }
@ -6307,6 +6314,7 @@ apply_modifiers_uncached (int modifiers, char *base, int base_len, int base_len_
if (modifiers & super_modifier) { *p++ = 's'; *p++ = '-'; }
if (modifiers & double_modifier) p = stpcpy (p, "double-");
if (modifiers & triple_modifier) p = stpcpy (p, "triple-");
if (modifiers & up_modifier) p = stpcpy (p, "up-");
if (modifiers & down_modifier) p = stpcpy (p, "down-");
if (modifiers & drag_modifier) p = stpcpy (p, "drag-");
/* The click modifier is denoted by the absence of other modifiers. */
@ -6426,8 +6434,7 @@ DEFUN ("internal-event-symbol-parse-modifiers", Fevent_symbol_parse_modifiers,
BASE must be unmodified.
This is like apply_modifiers_uncached, but uses BASE's
Qmodifier_cache property, if present. It also builds
Qevent_symbol_elements properties, since it has that info anyway.
Qmodifier_cache property, if present.
apply_modifiers copies the value of BASE's Qevent_kind property to
the modified symbol. */
@ -6773,6 +6780,10 @@ parse_solitary_modifier (Lisp_Object symbol)
MULTI_LETTER_MOD (triple_modifier, "triple", 6);
break;
case 'u':
MULTI_LETTER_MOD (up_modifier, "up", 2);
break;
#undef SINGLE_LETTER_MOD
#undef MULTI_LETTER_MOD
}
@ -9486,14 +9497,16 @@ read_key_sequence (Lisp_Object *keybuf, int bufsize, Lisp_Object prompt,
Drags reduce to clicks.
Double-clicks reduce to clicks.
Triple-clicks reduce to double-clicks, then to clicks.
Down-clicks are eliminated.
Up/Down-clicks are eliminated.
Double-downs reduce to downs, then are eliminated.
Triple-downs reduce to double-downs, then to downs,
then are eliminated. */
if (modifiers & (down_modifier | drag_modifier
if (modifiers & (up_modifier | down_modifier
| drag_modifier
| double_modifier | triple_modifier))
{
while (modifiers & (down_modifier | drag_modifier
while (modifiers & (up_modifier | down_modifier
| drag_modifier
| double_modifier | triple_modifier))
{
Lisp_Object new_head, new_click;
@ -9505,7 +9518,7 @@ read_key_sequence (Lisp_Object *keybuf, int bufsize, Lisp_Object prompt,
modifiers &= ~drag_modifier;
else
{
/* Dispose of this `down' event by simply jumping
/* Dispose of this `up/down' event by simply jumping
back to replay_key, to get another event.
Note that if this event came from mock input,