From abc12f7b8157c3981216d82ead60627db31a6c14 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 8 May 2018 02:23:36 -0700
Subject: [PATCH] Move null pool to hb-private

---
 src/dump-emoji.cc                  |  6 ++--
 src/dump-fon.cc                    | 14 ++++-----
 src/hb-aat-layout.cc               |  8 ++---
 src/hb-open-type-private.hh        | 48 ++----------------------------
 src/hb-ot-cmap-table.hh            |  4 +--
 src/hb-ot-color.cc                 |  4 +--
 src/hb-ot-layout-common-private.hh | 13 ++++++--
 src/hb-ot-layout.cc                | 22 +++++++-------
 src/hb-ot-math.cc                  |  4 +--
 src/hb-ot-var.cc                   |  6 ++--
 src/hb-private.hh                  | 29 ++++++++++++++++++
 src/hb-subset.cc                   |  4 +--
 src/main.cc                        |  2 +-
 13 files changed, 79 insertions(+), 85 deletions(-)

diff --git a/src/dump-emoji.cc b/src/dump-emoji.cc
index e173a5eef..19c061833 100644
--- a/src/dump-emoji.cc
+++ b/src/dump-emoji.cc
@@ -47,7 +47,7 @@
 #include <stdio.h>
 
 #ifndef HB_NO_VISIBILITY
-const void * const OT::_hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
+const void * const _hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
 #endif
 
 void cbdt_callback (const uint8_t* data, unsigned int length,
@@ -91,7 +91,7 @@ void svg_callback (const uint8_t* data, unsigned int length,
 void colr_cpal_rendering (cairo_font_face_t *cairo_face, unsigned int upem, unsigned int num_glyphs,
 			  const OT::COLR *colr, const OT::CPAL *cpal)
 {
-  for (int i = 0; i < num_glyphs; ++i)
+  for (unsigned int i = 0; i < num_glyphs; ++i)
   {
     unsigned int first_layer_index, num_layers;
     if (colr->get_base_glyph_record (i, &first_layer_index, &num_layers))
@@ -171,7 +171,7 @@ void dump_glyphs (cairo_font_face_t *cairo_face, unsigned int upem, unsigned int
 {
   // Dump every glyph available on the font
   return; // disabled for now
-  for (int i = 0; i < num_glyphs; ++i)
+  for (unsigned int i = 0; i < num_glyphs; ++i)
   {
     cairo_text_extents_t extents;
     cairo_glyph_t glyph = {0};
diff --git a/src/dump-fon.cc b/src/dump-fon.cc
index 1d18983ce..7e1fef618 100644
--- a/src/dump-fon.cc
+++ b/src/dump-fon.cc
@@ -27,7 +27,7 @@
 #include "hb-open-type-private.hh"
 
 #ifndef HB_NO_VISIBILITY
-const void * const OT::_hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
+const void * const _hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
 #endif
 
 template <typename Type, int Bytes> struct LEInt;
@@ -344,7 +344,7 @@ struct NE_TYPEINFO
   {
     const NE_TYPEINFO& next = OT::StructAfter<NE_TYPEINFO> (*this);
     if (type_id == 0)
-      return OT::Null (NE_TYPEINFO);
+      return Null (NE_TYPEINFO);
     return next;
   }
 
@@ -352,7 +352,7 @@ struct NE_TYPEINFO
   {
     if (idx < count)
       return resources[idx].get_font (base, shift);
-    return OT::Null (LE_FONTINFO16);
+    return Null (LE_FONTINFO16);
   }
 
   inline unsigned int get_count () const
@@ -401,7 +401,7 @@ struct NE_RESOURCE_TABLE
       return_trace (false);
 
     const NE_TYPEINFO* n = &chain;
-    while (n != &OT::Null (NE_TYPEINFO) && c->check_struct (n) && n->get_type_id () != 0)
+    while (n != &Null (NE_TYPEINFO) && c->check_struct (n) && n->get_type_id () != 0)
     {
       if (n->get_type_id () == NE_TYPEINFO::FONT)
 	return_trace (n->sanitize (c, base, alignmentShiftCount));
@@ -418,13 +418,13 @@ struct NE_RESOURCE_TABLE
   inline const NE_TYPEINFO& get_fonts_entry () const
   {
     const NE_TYPEINFO* n = &chain;
-    while (n != &OT::Null (NE_TYPEINFO) && n->get_type_id () != 0)
+    while (n != &Null (NE_TYPEINFO) && n->get_type_id () != 0)
     {
       if (n->get_type_id () == NE_TYPEINFO::FONT)
 	return *n;
       n = &n->next();
     }
-    return OT::Null (NE_TYPEINFO);
+    return Null (NE_TYPEINFO);
   }
 
   protected:
@@ -447,7 +447,7 @@ struct LE_IMAGE_OS2_HEADER
   inline const NE_RESOURCE_TABLE& get_resource_table () const
   {
     if (magic != 0x454E) // Only NE containers are support for now, NE == 0x454E
-      return OT::Null (NE_RESOURCE_TABLE);
+      return Null (NE_RESOURCE_TABLE);
     return this+rsrctab;
   }
 
diff --git a/src/hb-aat-layout.cc b/src/hb-aat-layout.cc
index 7bd60272d..18743e3cd 100644
--- a/src/hb-aat-layout.cc
+++ b/src/hb-aat-layout.cc
@@ -52,7 +52,7 @@ _get_ankr (hb_face_t *face, hb_blob_t **blob = nullptr)
   {
     if (blob)
       *blob = hb_blob_get_empty ();
-    return OT::Null(AAT::ankr);
+    return Null(AAT::ankr);
   }
   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
   const AAT::ankr& ankr = *(layout->ankr.get ());
@@ -68,7 +68,7 @@ _get_kerx (hb_face_t *face, hb_blob_t **blob = nullptr)
   {
     if (blob)
       *blob = hb_blob_get_empty ();
-    return OT::Null(AAT::kerx);
+    return Null(AAT::kerx);
   }
   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
   /* XXX this doesn't call set_num_glyphs on sanitizer. */
@@ -85,7 +85,7 @@ _get_morx (hb_face_t *face, hb_blob_t **blob = nullptr)
   {
     if (blob)
       *blob = hb_blob_get_empty ();
-    return OT::Null(AAT::morx);
+    return Null(AAT::morx);
   }
   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
   /* XXX this doesn't call set_num_glyphs on sanitizer. */
@@ -102,7 +102,7 @@ _get_trak (hb_face_t *face, hb_blob_t **blob = nullptr)
   {
     if (blob)
       *blob = hb_blob_get_empty ();
-    return OT::Null(AAT::trak);
+    return Null(AAT::trak);
   }
   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
   const AAT::trak& trak = *(layout->trak.get ());
diff --git a/src/hb-open-type-private.hh b/src/hb-open-type-private.hh
index 1f22b1825..68e0e410d 100644
--- a/src/hb-open-type-private.hh
+++ b/src/hb-open-type-private.hh
@@ -126,46 +126,6 @@ static inline Type& StructAfter(TObject &X)
 
 
 
-/*
- * Null objects
- */
-
-/* Global nul-content Null pool.  Enlarge as necessary. */
-
-#define HB_NULL_POOL_SIZE 264
-static_assert (HB_NULL_POOL_SIZE % sizeof (void *) == 0, "Align HB_NULL_POOL_SIZE.");
-
-#ifdef HB_NO_VISIBILITY
-static
-#else
-extern HB_INTERNAL
-#endif
-const void * const _hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)]
-#ifdef HB_NO_VISIBILITY
-= {}
-#endif
-;
-
-/* Generic nul-content Null objects. */
-template <typename Type>
-static inline const Type& Null (void) {
-  static_assert (sizeof (Type) <= HB_NULL_POOL_SIZE, "Increase HB_NULL_POOL_SIZE.");
-  return *CastP<Type> (_hb_NullPool);
-}
-
-/* Specializaiton for arbitrary-content arbitrary-sized Null objects. */
-#define DEFINE_NULL_DATA(Type, data) \
-static const char _Null##Type[sizeof (Type) + 1] = data; /* +1 is for nul-termination in data */ \
-template <> \
-/*static*/ inline const Type& Null<Type> (void) { \
-  return *CastP<Type> (_Null##Type); \
-} /* The following line really exists such that we end in a place needing semicolon */ \
-static_assert (Type::min_size + 1 <= sizeof (_Null##Type), "Null pool too small.  Enlarge.")
-
-/* Accessor macro. */
-#define Null(Type) Null<Type>()
-
-
 /*
  * Dispatch
  */
@@ -726,7 +686,6 @@ struct Tag : HBUINT32
   public:
   DEFINE_SIZE_STATIC (4);
 };
-DEFINE_NULL_DATA (Tag, "    ");
 
 /* Glyph index number, same as uint16 (length = 16 bits) */
 typedef HBUINT16 GlyphID;
@@ -738,7 +697,6 @@ typedef HBUINT16 NameID;
 struct Index : HBUINT16 {
   static const unsigned int NOT_FOUND_INDEX = 0xFFFFu;
 };
-DEFINE_NULL_DATA (Index, "\xff\xff");
 
 /* Offset, Null offset = 0 */
 template <typename Type>
@@ -1236,7 +1194,7 @@ struct hb_lazy_loader_t
 
   inline void fini (void)
   {
-    if (instance && instance != &OT::Null(T))
+    if (instance && instance != &Null(T))
     {
       instance->fini();
       free (instance);
@@ -1251,12 +1209,12 @@ struct hb_lazy_loader_t
     {
       p = (T *) calloc (1, sizeof (T));
       if (unlikely (!p))
-        p = const_cast<T *> (&OT::Null(T));
+        p = const_cast<T *> (&Null(T));
       else
 	p->init (face);
       if (unlikely (!hb_atomic_ptr_cmpexch (const_cast<T **>(&instance), nullptr, p)))
       {
-	if (p != &OT::Null(T))
+	if (p != &Null(T))
 	  p->fini ();
 	goto retry;
       }
diff --git a/src/hb-ot-cmap-table.hh b/src/hb-ot-cmap-table.hh
index 83a0b519b..caffda352 100644
--- a/src/hb-ot-cmap-table.hh
+++ b/src/hb-ot-cmap-table.hh
@@ -682,7 +682,7 @@ struct cmap
 	if (subtable) symbol = true;
       }
       /* Meh. */
-      if (!subtable) subtable = &OT::Null(OT::CmapSubtable);
+      if (!subtable) subtable = &Null(OT::CmapSubtable);
 
       /* UVS subtable. */
       if (!subtable_uvs)
@@ -692,7 +692,7 @@ struct cmap
 	  subtable_uvs = &st->u.format14;
       }
       /* Meh. */
-      if (!subtable_uvs) subtable_uvs = &OT::Null(OT::CmapSubtableFormat14);
+      if (!subtable_uvs) subtable_uvs = &Null(OT::CmapSubtableFormat14);
 
       this->uvs_table = subtable_uvs;
 
diff --git a/src/hb-ot-color.cc b/src/hb-ot-color.cc
index ceebe0b7a..86171c633 100644
--- a/src/hb-ot-color.cc
+++ b/src/hb-ot-color.cc
@@ -44,7 +44,7 @@ HB_MARK_AS_FLAG_T (hb_ot_color_palette_flags_t)
 static inline const OT::COLR&
 _get_colr (hb_face_t *face)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::COLR);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::COLR);
   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
   return *(layout->colr.get ());
 }
@@ -52,7 +52,7 @@ _get_colr (hb_face_t *face)
 static inline const OT::CPAL&
 _get_cpal (hb_face_t *face)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::CPAL);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::CPAL);
   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
   return *(layout->cpal.get ());
 }
diff --git a/src/hb-ot-layout-common-private.hh b/src/hb-ot-layout-common-private.hh
index bd193f9dc..bec694e18 100644
--- a/src/hb-ot-layout-common-private.hh
+++ b/src/hb-ot-layout-common-private.hh
@@ -165,7 +165,6 @@ struct RangeRecord
   public:
   DEFINE_SIZE_STATIC (6);
 };
-DEFINE_NULL_DATA (RangeRecord, "\000\001");
 
 
 struct IndexArray : ArrayOf<Index>
@@ -225,7 +224,6 @@ struct LangSys
   public:
   DEFINE_SIZE_ARRAY (6, featureIndex);
 };
-DEFINE_NULL_DATA (LangSys, "\0\0\xFF\xFF");
 
 
 struct Script
@@ -247,7 +245,16 @@ struct Script
   { return langSys.find_index (tag, index); }
 
   inline bool has_default_lang_sys (void) const { return defaultLangSys != 0; }
-  inline const LangSys& get_default_lang_sys (void) const { return this+defaultLangSys; }
+  inline const LangSys& get_default_lang_sys (void) const
+  {
+    if (!defaultLangSys)
+    {
+      /* This is the ONLY place where our null data is not all zeros.
+       * So, return special data instead of using the null pool. */
+      return *reinterpret_cast<const LangSys *> ("\0\0\xFF\xFF");
+    }
+    return this+defaultLangSys;
+  }
 
   inline bool sanitize (hb_sanitize_context_t *c,
 			const Record<Script>::sanitize_closure_t * = nullptr) const
diff --git a/src/hb-ot-layout.cc b/src/hb-ot-layout.cc
index f7e496486..5ee03dc8a 100644
--- a/src/hb-ot-layout.cc
+++ b/src/hb-ot-layout.cc
@@ -47,7 +47,7 @@
 
 
 #ifndef HB_NO_VISIBILITY
-const void * const OT::_hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
+const void * const _hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
 #endif
 
 
@@ -102,7 +102,7 @@ _hb_ot_layout_create (hb_face_t *face)
        * https://lists.freedesktop.org/archives/harfbuzz/2016-February/005489.html
        */
      if (3 == layout->gdef->get_glyph_class (5))
-       layout->gdef = &OT::Null(OT::GDEF);
+       layout->gdef = &Null(OT::GDEF);
     }
     else if (0
       /* sha1sum:96eda93f7d33e79962451c6c39a6b51ee893ce8c  tahoma.ttf from Windows 8 */
@@ -174,7 +174,7 @@ _hb_ot_layout_create (hb_face_t *face)
        *     https://bugzilla.mozilla.org/show_bug.cgi?id=1279693
        *     https://bugzilla.mozilla.org/show_bug.cgi?id=1279875
        */
-      layout->gdef = &OT::Null(OT::GDEF);
+      layout->gdef = &Null(OT::GDEF);
     }
   }
 
@@ -226,7 +226,7 @@ _hb_ot_layout_destroy (hb_ot_layout_t *layout)
 // static inline const OT::BASE&
 // _get_base (hb_face_t *face)
 // {
-//   if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::BASE);
+//   if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::BASE);
 //   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
 //   return *(layout->base.get ());
 // }
@@ -234,19 +234,19 @@ _hb_ot_layout_destroy (hb_ot_layout_t *layout)
 static inline const OT::GDEF&
 _get_gdef (hb_face_t *face)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GDEF);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::GDEF);
   return *hb_ot_layout_from_face (face)->gdef;
 }
 static inline const OT::GSUB&
 _get_gsub (hb_face_t *face)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GSUB);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::GSUB);
   return *hb_ot_layout_from_face (face)->gsub;
 }
 static inline const OT::GPOS&
 _get_gpos (hb_face_t *face)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GPOS);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::GPOS);
   return *hb_ot_layout_from_face (face)->gpos;
 }
 
@@ -318,7 +318,7 @@ get_gsubgpos_table (hb_face_t *face,
   switch (table_tag) {
     case HB_OT_TAG_GSUB: return _get_gsub (face);
     case HB_OT_TAG_GPOS: return _get_gpos (face);
-    default:             return OT::Null(OT::GSUBGPOS);
+    default:             return Null(OT::GSUBGPOS);
   }
 }
 
@@ -898,7 +898,7 @@ hb_ot_layout_feature_with_variations_get_lookups (hb_face_t    *face,
 hb_bool_t
 hb_ot_layout_has_substitution (hb_face_t *face)
 {
-  return &_get_gsub (face) != &OT::Null(OT::GSUB);
+  return &_get_gsub (face) != &Null(OT::GSUB);
 }
 
 /**
@@ -962,7 +962,7 @@ hb_ot_layout_lookup_substitute_closure (hb_face_t    *face,
 hb_bool_t
 hb_ot_layout_has_positioning (hb_face_t *face)
 {
-  return &_get_gpos (face) != &OT::Null(OT::GPOS);
+  return &_get_gpos (face) != &Null(OT::GPOS);
 }
 
 void
@@ -1298,5 +1298,5 @@ hb_ot_layout_substitute_lookup (OT::hb_ot_apply_context_t *c,
 // hb_bool_t
 // hb_ot_base_has_data (hb_face_t *face)
 // {
-//   return &_get_base (face) != &OT::Null(OT::BASE);
+//   return &_get_base (face) != &Null(OT::BASE);
 // }
diff --git a/src/hb-ot-math.cc b/src/hb-ot-math.cc
index f82a07353..1667a7da8 100644
--- a/src/hb-ot-math.cc
+++ b/src/hb-ot-math.cc
@@ -32,7 +32,7 @@
 static inline const OT::MATH&
 _get_math (hb_face_t *face)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::MATH);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::MATH);
   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
   return *(layout->math.get ());
 }
@@ -55,7 +55,7 @@ _get_math (hb_face_t *face)
 hb_bool_t
 hb_ot_math_has_data (hb_face_t *face)
 {
-  return &_get_math (face) != &OT::Null(OT::MATH);
+  return &_get_math (face) != &Null(OT::MATH);
 }
 
 /**
diff --git a/src/hb-ot-var.cc b/src/hb-ot-var.cc
index 90ba0bd02..f0612a611 100644
--- a/src/hb-ot-var.cc
+++ b/src/hb-ot-var.cc
@@ -39,14 +39,14 @@
 static inline const OT::fvar&
 _get_fvar (hb_face_t *face)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::fvar);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::fvar);
   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
   return *(layout->fvar.get ());
 }
 static inline const OT::avar&
 _get_avar (hb_face_t *face)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::avar);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(OT::avar);
   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
   return *(layout->avar.get ());
 }
@@ -65,7 +65,7 @@ _get_avar (hb_face_t *face)
 hb_bool_t
 hb_ot_var_has_data (hb_face_t *face)
 {
-  return &_get_fvar (face) != &OT::Null(OT::fvar);
+  return &_get_fvar (face) != &Null(OT::fvar);
 }
 
 /**
diff --git a/src/hb-private.hh b/src/hb-private.hh
index 21561ce44..9e075a312 100644
--- a/src/hb-private.hh
+++ b/src/hb-private.hh
@@ -1089,4 +1089,33 @@ round (double x)
 #endif
 
 
+/*
+ * Null objects
+ */
+
+/* Global nul-content Null pool.  Enlarge as necessary. */
+
+#define HB_NULL_POOL_SIZE 264
+static_assert (HB_NULL_POOL_SIZE % sizeof (void *) == 0, "Align HB_NULL_POOL_SIZE.");
+
+#ifdef HB_NO_VISIBILITY
+static
+#else
+extern HB_INTERNAL
+#endif
+const void * const _hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)]
+#ifdef HB_NO_VISIBILITY
+= {}
+#endif
+;
+
+/* Generic nul-content Null objects. */
+template <typename Type>
+static inline const Type& Null (void) {
+  static_assert (sizeof (Type) <= HB_NULL_POOL_SIZE, "Increase HB_NULL_POOL_SIZE.");
+  return *reinterpret_cast<const Type *> (_hb_NullPool);
+}
+#define Null(Type) Null<Type>()
+
+
 #endif /* HB_PRIVATE_HH */
diff --git a/src/hb-subset.cc b/src/hb-subset.cc
index 35fe0ef84..6c3d75917 100644
--- a/src/hb-subset.cc
+++ b/src/hb-subset.cc
@@ -45,7 +45,7 @@
 
 
 #if !defined(HB_NO_VISIBILITY) && !defined(HB_SUBSET_BUILTIN)
-const void * const OT::_hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
+const void * const _hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
 #endif
 
 
@@ -91,7 +91,7 @@ _subset (hb_subset_plan_t *plan)
 
   hb_tag_t tag = TableType::tableTag;
   hb_bool_t result = false;
-  if (table != &OT::Null(TableType))
+  if (table != &Null(TableType))
   {
     result = table->subset(plan);
   } else {
diff --git a/src/main.cc b/src/main.cc
index 935fa3929..0436c85f8 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -38,7 +38,7 @@
 using namespace OT;
 
 #ifndef HB_NO_VISIBILITY
-const void * const OT::_hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
+const void * const _hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
 #endif
 
 int