[OT] Really fix possible NULL dereference this time

src/hb-ot-layout-gsubgpos-private.hh

@@ -86,13 +86,13 @@ struct hb_would_apply_context_t
 			    const hb_codepoint_t *glyphs_,
 			    unsigned int len_,
 			    bool zero_context_,
-			    const hb_set_digest_t *digest_
+			    const hb_set_digest_t &digest_
 			    ) :
 			      face (face_),
 			      glyphs (glyphs_),
 			      len (len_),
 			      zero_context (zero_context_),
-			      digest (digest_ ? *digest_ : hb_set_digest_t()),
+			      digest (digest_),
 			      debug_depth (0) {};
 };
 
@@ -124,7 +124,7 @@ struct hb_apply_context_t
   hb_apply_context_t (hb_font_t *font_,
 		      hb_buffer_t *buffer_,
 		      hb_mask_t lookup_mask_,
-		      const hb_set_digest_t *digest_) :
+		      const hb_set_digest_t &digest_) :
 			font (font_), face (font->face), buffer (buffer_),
 			direction (buffer_->props.direction),
 			lookup_mask (lookup_mask_),
@@ -132,7 +132,7 @@ struct hb_apply_context_t
 			lookup_props (0), property (0), debug_depth (0),
 			gdef (*hb_ot_layout_from_face (face)->gdef),
 			has_glyph_classes (gdef.has_glyph_classes ()),
-			digest (*digest_) {}
+			digest (digest_) {}
 
   void set_lookup_props (unsigned int lookup_props_) {
     lookup_props = lookup_props_;

src/hb-ot-layout.cc

@@ -417,7 +417,7 @@ hb_ot_layout_would_substitute_lookup_fast (hb_face_t            *face,
 					   hb_bool_t             zero_context)
 {
   if (unlikely (lookup_index >= hb_ot_layout_from_face (face)->gsub_lookup_count)) return false;
-  OT::hb_would_apply_context_t c (face, glyphs, glyphs_length, zero_context, &hb_ot_layout_from_face (face)->gsub_digests[lookup_index]);
+  OT::hb_would_apply_context_t c (face, glyphs, glyphs_length, zero_context, hb_ot_layout_from_face (face)->gsub_digests[lookup_index]);
   return hb_ot_layout_from_face (face)->gsub->would_substitute_lookup (&c, lookup_index);
 }
 
@@ -434,7 +434,7 @@ hb_ot_layout_substitute_lookup (hb_font_t    *font,
 				hb_mask_t     mask)
 {
   if (unlikely (lookup_index >= hb_ot_layout_from_face (font->face)->gsub_lookup_count)) return false;
-  OT::hb_apply_context_t c (font, buffer, mask, &hb_ot_layout_from_face (font->face)->gsub_digests[lookup_index]);
+  OT::hb_apply_context_t c (font, buffer, mask, hb_ot_layout_from_face (font->face)->gsub_digests[lookup_index]);
   return hb_ot_layout_from_face (font->face)->gsub->substitute_lookup (&c, lookup_index);
 }
 
@@ -476,7 +476,7 @@ hb_ot_layout_position_lookup (hb_font_t    *font,
 			      hb_mask_t     mask)
 {
   if (unlikely (lookup_index >= hb_ot_layout_from_face (font->face)->gpos_lookup_count)) return false;
-  OT::hb_apply_context_t c (font, buffer, mask, &hb_ot_layout_from_face (font->face)->gpos_digests[lookup_index]);
+  OT::hb_apply_context_t c (font, buffer, mask, hb_ot_layout_from_face (font->face)->gpos_digests[lookup_index]);
   return hb_ot_layout_from_face (font->face)->gpos->position_lookup (&c, lookup_index);
 }
 

src/hb-ot-shape-complex-arabic.cc

@@ -246,7 +246,9 @@ arabic_fallback_shape (hb_font_t *font, hb_buffer_t *buffer)
       buffer->info[i].codepoint = shaped;
   }
 
-  OT::hb_apply_context_t c (font, buffer, 1/*global mask*/, NULL);
+  hb_set_digest_t digest;
+  digest.init ();
+  OT::hb_apply_context_t c (font, buffer, 1/*global mask*/, digest);
   c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
 
   /* Mandatory ligatures */