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[aat] Limit number of DontAdvance transitions

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Remove the faulty loop-detection logic. Use max-ops for breaking
out of infinite loops or heavy work.

https://twitter.com/behdadesfahbod/status/958065026262183936
This commit is contained in:
Behdad Esfahbod 2018-01-30 10:58:44 -08:00
parent e00743b47d
commit e89df6e1ae
1 changed files with 2 additions and 31 deletions
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33
src/hb-aat-layout-common-private.hh
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@ -615,13 +615,7 @@ struct StateTableDriver
machine (machine_),
buffer (buffer_),
num_glyphs (face_->get_num_glyphs ()),
last_zero (0),
dont_advance_set (nullptr) {}
inline ~StateTableDriver (void)
{
hb_set_destroy (dont_advance_set);
}
last_zero (0) {}
template <typename context_t>
inline void drive (context_t *c)
@ -648,27 +642,7 @@ struct StateTableDriver
if (unlikely (!c->transition (this, entry)))
break;
if (entry->flags & context_t::DontAdvance)
{
if (!last_was_dont_advance)
{
if (dont_advance_set)
dont_advance_set->clear ();
else
dont_advance_set = hb_set_create ();
}
unsigned int key = info[buffer->idx].codepoint ^ (state << 16);
if (likely (!dont_advance_set->has (key)))
{
dont_advance_set->add (key);
last_was_dont_advance = true;
}
else
last_was_dont_advance = false;
}
else
last_was_dont_advance = false;
last_was_dont_advance = (entry->flags & context_t::DontAdvance) && buffer->max_ops--;
state = entry->newState;
@ -692,9 +666,6 @@ struct StateTableDriver
hb_buffer_t *buffer;
unsigned int num_glyphs;
unsigned int last_zero;
private:
hb_set_t *dont_advance_set; /* Infinite-loop detection */
};