Do not allow recursiving to same position and same lookup

This is just to make it harder to be extremely slow.  There definitely
are ways still, just harder.  Oh well... how do we tame this problem
without solving halting problem?!

Fixes https://github.com/behdad/harfbuzz/issues/174
This commit is contained in:
Behdad Esfahbod 2015-11-19 12:39:09 -08:00
parent 7d75eee799
commit 9cc1ed4fa6
4 changed files with 7 additions and 0 deletions

View File

@ -971,6 +971,11 @@ static inline bool apply_lookup (hb_apply_context_t *c,
if (idx >= count)
continue;
/* Don't recurse to ourself at same position.
* Note that this test is too naive, it doesn't catch longer loops. */
if (idx == 0 && lookupRecord[i].lookupListIndex == c->lookup_index)
continue;
buffer->move_to (match_positions[idx]);
unsigned int orig_len = buffer->backtrack_len () + buffer->lookahead_len ();

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@ -34,3 +34,4 @@ df768b9c257e0c9c35786c47cae15c46571d56be.ttf
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