[AAT] Handle transition errors during machine operation

Before we used to give up.  Now, just ignore error and continue processing.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1531

src/hb-aat-layout-common.hh

@@ -777,8 +777,7 @@ struct StateTableDriver
 	  buffer->unsafe_to_break (buffer->idx, buffer->idx + 2);
       }
 
-      if (unlikely (!c->transition (this, entry)))
+      c->transition (this, entry);
-	;//break; Ignore error.
 
       state = machine.new_state (entry.newState);
       DEBUG_MSG (APPLY, nullptr, "s%d", state);

src/hb-aat-layout-kerx-table.hh

@@ -232,7 +232,7 @@ struct KerxSubTableFormat1
     {
       return Format1EntryT::performAction (entry);
     }
-    bool transition (StateTableDriver<Types, EntryData> *driver,
+    void transition (StateTableDriver<Types, EntryData> *driver,
 		     const Entry<EntryData> &entry)
     {
       hb_buffer_t *buffer = driver->buffer;
@@ -259,7 +259,7 @@ struct KerxSubTableFormat1
 	if (!c->sanitizer.check_array (actions, depth, tuple_count))
 	{
 	  depth = 0;
-	  return false;
+	  return;
 	}
 
 	hb_mask_t kern_mask = c->plan->kern_mask;
@@ -334,8 +334,6 @@ struct KerxSubTableFormat1
 	  }
 	}
       }
-
-      return true;
     }
 
     private:
@@ -502,7 +500,7 @@ struct KerxSubTableFormat4
     {
       return entry.data.ankrActionIndex != 0xFFFF;
     }
-    bool transition (StateTableDriver<Types, EntryData> *driver,
+    void transition (StateTableDriver<Types, EntryData> *driver,
 		     const Entry<EntryData> &entry)
     {
       hb_buffer_t *buffer = driver->buffer;
@@ -516,8 +514,7 @@ struct KerxSubTableFormat4
 	  {
 	    /* indexed into glyph outline. */
 	    const HBUINT16 *data = &ankrData[entry.data.ankrActionIndex];
-	    if (!c->sanitizer.check_array (data, 2))
+	    if (!c->sanitizer.check_array (data, 2)) return;
-	      return false;
 	    HB_UNUSED unsigned int markControlPoint = *data++;
 	    HB_UNUSED unsigned int currControlPoint = *data++;
 	    hb_position_t markX = 0;
@@ -532,7 +529,7 @@ struct KerxSubTableFormat4
 							      currControlPoint,
 							      HB_DIRECTION_LTR /*XXX*/,
 							      &currX, &currY))
-	      return true; /* True, such that the machine continues. */
+	      return;
 
 	    o.x_offset = markX - currX;
 	    o.y_offset = markY - currY;
@@ -543,8 +540,7 @@ struct KerxSubTableFormat4
 	  {
 	   /* Indexed into 'ankr' table. */
 	    const HBUINT16 *data = &ankrData[entry.data.ankrActionIndex];
-	    if (!c->sanitizer.check_array (data, 2))
+	    if (!c->sanitizer.check_array (data, 2)) return;
-	      return false;
 	    unsigned int markAnchorPoint = *data++;
 	    unsigned int currAnchorPoint = *data++;
 	    const Anchor &markAnchor = c->ankr_table->get_anchor (c->buffer->info[mark].codepoint,
@@ -562,8 +558,7 @@ struct KerxSubTableFormat4
 	  case 2: /* Control Point Coordinate Actions. */
 	  {
 	    const FWORD *data = (const FWORD *) &ankrData[entry.data.ankrActionIndex];
-	    if (!c->sanitizer.check_array (data, 4))
+	    if (!c->sanitizer.check_array (data, 4)) return;
-	      return false;
 	    int markX = *data++;
 	    int markY = *data++;
 	    int currX = *data++;
@@ -584,8 +579,6 @@ struct KerxSubTableFormat4
 	mark_set = true;
 	mark = buffer->idx;
       }
-
-      return true;
     }
 
     private:

src/hb-aat-layout-morx-table.hh

@@ -78,7 +78,7 @@ struct RearrangementSubtable
     {
       return (entry.flags & Verb) && start < end;
     }
-    bool transition (StateTableDriver<Types, EntryData> *driver,
+    void transition (StateTableDriver<Types, EntryData> *driver,
 		     const Entry<EntryData> &entry)
     {
       hb_buffer_t *buffer = driver->buffer;
@@ -152,8 +152,6 @@ struct RearrangementSubtable
 	  }
 	}
       }
-
-      return true;
     }
 
     public:
@@ -232,7 +230,7 @@ struct ContextualSubtable
 
       return entry.data.markIndex != 0xFFFF || entry.data.currentIndex != 0xFFFF;
     }
-    bool transition (StateTableDriver<Types, EntryData> *driver,
+    void transition (StateTableDriver<Types, EntryData> *driver,
 		     const Entry<EntryData> &entry)
     {
       hb_buffer_t *buffer = driver->buffer;
@@ -240,7 +238,7 @@ struct ContextualSubtable
       /* Looks like CoreText applies neither mark nor current substitution for
        * end-of-text if mark was not explicitly set. */
       if (buffer->idx == buffer->len && !mark_set)
-        return true;
+        return;
 
       const GlyphID *replacement;
 
@@ -297,8 +295,6 @@ struct ContextualSubtable
 	mark_set = true;
 	mark = buffer->idx;
       }
-
-      return true;
     }
 
     public:
@@ -457,7 +453,7 @@ struct LigatureSubtable
     {
       return LigatureEntryT::performAction (entry);
     }
-    bool transition (StateTableDriver<Types, EntryData> *driver,
+    void transition (StateTableDriver<Types, EntryData> *driver,
 		     const Entry<EntryData> &entry)
     {
       hb_buffer_t *buffer = driver->buffer;
@@ -466,7 +462,7 @@ struct LigatureSubtable
       if (entry.flags & LigatureEntryT::SetComponent)
       {
         if (unlikely (match_length >= ARRAY_LENGTH (match_positions)))
-	  return false;
+	  match_length = 0; /* TODO Use a ring buffer instead. */
 
 	/* Never mark same index twice, in case DontAdvance was used... */
 	if (match_length && match_positions[match_length - 1] == buffer->out_len)
@@ -482,10 +478,10 @@ struct LigatureSubtable
 	unsigned int end = buffer->out_len;
 
 	if (unlikely (!match_length))
-	  return true;
+	  return;
 
 	if (buffer->idx >= buffer->len)
-	  return false; // TODO Work on previous instead?
+	  return; // TODO Work on previous instead?
 
 	unsigned int cursor = match_length;
 
@@ -508,7 +504,7 @@ struct LigatureSubtable
 	  DEBUG_MSG (APPLY, nullptr, "Moving to stack position %u", cursor - 1);
 	  buffer->move_to (match_positions[--cursor]);
 
-	  if (unlikely (!actionData->sanitize (&c->sanitizer))) return false;
+	  if (unlikely (!actionData->sanitize (&c->sanitizer))) break;
 	  action = *actionData;
 
 	  uint32_t uoffset = action & LigActionOffset;
@@ -518,7 +514,7 @@ struct LigatureSubtable
 	  unsigned int component_idx = buffer->cur().codepoint + offset;
 	  component_idx = Types::wordOffsetToIndex (component_idx, table, component.arrayZ);
 	  const HBUINT16 &componentData = component[component_idx];
-	  if (unlikely (!componentData.sanitize (&c->sanitizer))) return false;
+	  if (unlikely (!componentData.sanitize (&c->sanitizer))) break;
 	  ligature_idx += componentData;
 
 	  DEBUG_MSG (APPLY, nullptr, "Action store %u last %u",
@@ -528,7 +524,7 @@ struct LigatureSubtable
 	  {
 	    ligature_idx = Types::offsetToIndex (ligature_idx, table, ligature.arrayZ);
 	    const GlyphID &ligatureData = ligature[ligature_idx];
-	    if (unlikely (!ligatureData.sanitize (&c->sanitizer))) return false;
+	    if (unlikely (!ligatureData.sanitize (&c->sanitizer))) break;
 	    hb_codepoint_t lig = ligatureData;
 
 	    DEBUG_MSG (APPLY, nullptr, "Produced ligature %u", lig);
@@ -552,8 +548,6 @@ struct LigatureSubtable
 	while (!(action & LigActionLast));
 	buffer->move_to (end);
       }
-
-      return true;
     }
 
     public:
@@ -723,7 +717,7 @@ struct InsertionSubtable
       return (entry.flags & (CurrentInsertCount | MarkedInsertCount)) &&
 	     (entry.data.currentInsertIndex != 0xFFFF ||entry.data.markedInsertIndex != 0xFFFF);
     }
-    bool transition (StateTableDriver<Types, EntryData> *driver,
+    void transition (StateTableDriver<Types, EntryData> *driver,
 		     const Entry<EntryData> &entry)
     {
       hb_buffer_t *buffer = driver->buffer;
@@ -736,7 +730,7 @@ struct InsertionSubtable
 	unsigned int count = (flags & MarkedInsertCount);
 	unsigned int start = entry.data.markedInsertIndex;
 	const GlyphID *glyphs = &insertionAction[start];
-	if (unlikely (!c->sanitizer.check_array (glyphs, count))) return false;
+	if (unlikely (!c->sanitizer.check_array (glyphs, count))) count = 0;
 
 	bool before = flags & MarkedInsertBefore;
 
@@ -764,7 +758,7 @@ struct InsertionSubtable
 	unsigned int count = (flags & CurrentInsertCount) >> 5;
 	unsigned int start = entry.data.currentInsertIndex;
 	const GlyphID *glyphs = &insertionAction[start];
-	if (unlikely (!c->sanitizer.check_array (glyphs, count))) return false;
+	if (unlikely (!c->sanitizer.check_array (glyphs, count))) count = 0;
 
 	bool before = flags & CurrentInsertBefore;
 
@@ -795,8 +789,6 @@ struct InsertionSubtable
 	 */
 	buffer->move_to ((flags & DontAdvance) ? end : end + count);
       }
-
-      return true;
     }
 
     public: