[aat] Improve unsafe-to-break logic
Reduces false-positives. See comments for new logic. Fixes https://github.com/harfbuzz/harfbuzz/issues/2860 Adjusts run-tests.sh to allow unhashed absolute filenames.
This commit is contained in:
Behdad Esfahbod
parent
cf203936d7
commit
d8ea552d10
@ -730,6 +730,7 @@ template <typename Types, typename EntryData>
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struct StateTableDriver
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{
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using StateTableT = StateTable<Types, EntryData>;
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using EntryT = Entry<EntryData>;
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StateTableDriver (const StateTableT &machine_,
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hb_buffer_t *buffer_,
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@ -751,33 +752,79 @@ struct StateTableDriver
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machine.get_class (buffer->info[buffer->idx].codepoint, num_glyphs) :
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(unsigned) StateTableT::CLASS_END_OF_TEXT;
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DEBUG_MSG (APPLY, nullptr, "c%u at %u", klass, buffer->idx);
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const Entry<EntryData> &entry = machine.get_entry (state, klass);
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const EntryT &entry = machine.get_entry (state, klass);
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const int next_state = machine.new_state (entry.newState);
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/* Unsafe-to-break before this if not in state 0, as things might
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* go differently if we start from state 0 here.
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/* Conditions under which it's guaranteed safe-to-break before current glyph:
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*
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* Ugh. The indexing here is ugly... */
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if (state && buffer->backtrack_len () && buffer->idx < buffer->len)
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{
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/* If there's no action and we're just epsilon-transitioning to state 0,
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* safe to break. */
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if (c->is_actionable (this, entry) ||
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!(entry.newState == StateTableT::STATE_START_OF_TEXT &&
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entry.flags == context_t::DontAdvance))
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buffer->unsafe_to_break_from_outbuffer (buffer->backtrack_len () - 1, buffer->idx + 1);
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}
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* 1. There was no action in this transition; and
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*
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* 2. If we break before current glyph, the results will be the same. That
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* is guaranteed if:
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*
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* 2a. We were already in start-of-text state; or
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*
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* 2b. We are epsilon-transitioning to start-of-text state; or
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*
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* 2c. Starting from start-of-text state seeing current glyph:
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*
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* 2c'. There won't be any actions; and
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*
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* 2c". We would end up in the same state that we were going to end up
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* in now, including whether epsilon-transitioning.
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*
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* and
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*
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* 3. If we break before current glyph, there won't be any end-of-text action
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* after previous glyph.
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*
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* This triples the transitions we need to look up, but is worth returning
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* granular unsafe-to-break results. See eg.:
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*
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* https://github.com/harfbuzz/harfbuzz/issues/2860
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*/
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const EntryT *wouldbe_entry;
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bool safe_to_break =
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/* 1. */
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!c->is_actionable (this, entry)
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&&
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/* 2. */
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(
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/* 2a. */
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state == StateTableT::STATE_START_OF_TEXT
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/* 2b. */
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(
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(entry.flags & context_t::DontAdvance) &&
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next_state == StateTableT::STATE_START_OF_TEXT
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)
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/* 2c. */
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(
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wouldbe_entry = &machine.get_entry (StateTableT::STATE_START_OF_TEXT, klass)
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,
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/* 2c'. */
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!c->is_actionable (this, *wouldbe_entry)
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&&
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/* 2c". */
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(
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next_state == machine.new_state (wouldbe_entry->newState)
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&&
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(entry.flags & context_t::DontAdvance) == (wouldbe_entry->flags & context_t::DontAdvance)
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)
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)
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)
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&&
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/* 3. */
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!c->is_actionable (this, machine.get_entry (state, StateTableT::CLASS_END_OF_TEXT))
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;
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/* Unsafe-to-break if end-of-text would kick in here. */
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if (buffer->backtrack_len () && buffer->idx < buffer->len)
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{
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const Entry<EntryData> &end_entry = machine.get_entry (state, StateTableT::CLASS_END_OF_TEXT);
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if (c->is_actionable (this, end_entry))
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buffer->unsafe_to_break_from_outbuffer (buffer->backtrack_len () - 1, buffer->idx + 1);
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}
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if (!safe_to_break && buffer->backtrack_len () && buffer->idx < buffer->len)
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buffer->unsafe_to_break_from_outbuffer (buffer->backtrack_len () - 1, buffer->idx + 1);
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c->transition (this, entry);
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state = machine.new_state (entry.newState);
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state = next_state;
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DEBUG_MSG (APPLY, nullptr, "s%d", state);
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if (buffer->idx == buffer->len || unlikely (!buffer->successful))
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@ -1,3 +1,6 @@
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# https://github.com/harfbuzz/harfbuzz/pull/2871
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/System/Library/Fonts/LucidaGrande.ttc:--font-funcs ot --show-flags:U+0041,U+0042,U+0043,U+0044:[A=0+1413|B=1+1178|C=2+1417|D=3+1534]
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# 10.12.6 https://gist.github.com/ebraminio/1704341fa16b06979e605aafd88198cf
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/System/Library/Fonts/Helvetica.dfont@c7bec2785a4c402b7809b5e35337c3d24c18e281:--font-funcs ot:U+006D,U+0300:[m=0+1706|gravecmb=0@-284,10+0]
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/System/Library/Fonts/LucidaGrande.ttc@d89a9d7e57767bfe3b5a4cfd22bb1e9dbe03a062:--font-funcs ot:U+006D,U+0300:[mgrave=0+1912]
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@ -67,17 +67,18 @@ for filename in args:
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if os.name == 'nt': # Skip on Windows
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continue
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fontfile, expected_hash = fontfile.split('@')
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fontfile, expected_hash = (fontfile.split('@') + [''])[:2]
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try:
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with open (fontfile, 'rb') as ff:
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actual_hash = hashlib.sha1 (ff.read()).hexdigest ().strip ()
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if actual_hash != expected_hash:
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print ('different version of %s found; Expected hash %s, got %s; skipping.' %
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(fontfile, expected_hash, actual_hash))
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skips += 1
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continue
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except:
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if expected_hash:
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actual_hash = hashlib.sha1 (ff.read()).hexdigest ().strip ()
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if actual_hash != expected_hash:
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print ('different version of %s found; Expected hash %s, got %s; skipping.' %
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(fontfile, expected_hash, actual_hash))
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skips += 1
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continue
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except IOError:
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print ('%s not found, skip.' % fontfile)
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skips += 1
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continue
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