1 files changed, 111 insertions, 45 deletions

diff --git a/third_party/harfbuzz-ng/src/hb-shape.cc b/third_party/harfbuzz-ng/src/hb-shape.cc
index d97028e..56c9046 100644
--- a/third_party/harfbuzz-ng/src/hb-shape.cc
+++ b/third_party/harfbuzz-ng/src/hb-shape.cc
@@ -47,10 +47,10 @@ typedef hb_bool_t (*hb_shape_func_t) (hb_font_t          *font,
 				      unsigned int        num_features);
 
 #define HB_SHAPER_IMPLEMENT(name) {#name, _hb_##name##_shape}
-static struct hb_shaper_pair_t {
+static const struct hb_shaper_pair_t {
   char name[16];
   hb_shape_func_t func;
-} shapers[] = {
+} all_shapers[] = {
   /* v--- Add new shapers in the right place here */
 #ifdef HAVE_GRAPHITE
   HB_SHAPER_IMPLEMENT (graphite2),
@@ -65,55 +65,120 @@ static struct hb_shaper_pair_t {
 };
 #undef HB_SHAPER_IMPLEMENT
 
-static struct static_shaper_list_t
+
+/* Thread-safe, lock-free, shapers */
+
+static hb_shaper_pair_t *static_shapers;
+
+static
+void free_static_shapers (void)
+{
+  if (unlikely (static_shapers != all_shapers))
+    free (static_shapers);
+}
+
+static const hb_shaper_pair_t *
+get_shapers (void)
 {
-  static_shaper_list_t (void)
+retry:
+  hb_shaper_pair_t *shapers = (hb_shaper_pair_t *) hb_atomic_ptr_get (&static_shapers);
+
+  if (unlikely (!shapers))
   {
     char *env = getenv ("HB_SHAPER_LIST");
-    if (env && *env)
-    {
-       /* Reorder shaper list to prefer requested shaper list. */
-      unsigned int i = 0;
-      char *end, *p = env;
-      for (;;) {
-        end = strchr (p, ',');
-        if (!end)
-          end = p + strlen (p);
-
-	for (unsigned int j = i; j < ARRAY_LENGTH (shapers); j++)
-	  if (end - p == (int) strlen (shapers[j].name) &&
-	      0 == strncmp (shapers[j].name, p, end - p))
-	  {
-	    /* Reorder this shaper to position i */
-	   struct hb_shaper_pair_t t = shapers[j];
-	   memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));
-	   shapers[i] = t;
-	   i++;
-	  }
-
-        if (!*end)
-          break;
-        else
-          p = end + 1;
-      }
+    if (!env || !*env) {
+      (void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, (const hb_shaper_pair_t *) all_shapers);
+      return (const hb_shaper_pair_t *) all_shapers;
     }
 
-    ASSERT_STATIC ((ARRAY_LENGTH (shapers) + 1) * sizeof (*shaper_list) <= sizeof (shaper_list));
-    unsigned int i;
-    for (i = 0; i < ARRAY_LENGTH (shapers); i++)
-      shaper_list[i] = shapers[i].name;
-    shaper_list[i] = NULL;
+    /* Not found; allocate one. */
+    shapers = (hb_shaper_pair_t *) malloc (sizeof (all_shapers));
+    if (unlikely (!shapers))
+      return (const hb_shaper_pair_t *) all_shapers;
+     memcpy (shapers, all_shapers, sizeof (all_shapers));
+
+     /* Reorder shaper list to prefer requested shapers. */
+    unsigned int i = 0;
+    char *end, *p = env;
+    for (;;) {
+      end = strchr (p, ',');
+      if (!end)
+	end = p + strlen (p);
+
+      for (unsigned int j = i; j < ARRAY_LENGTH (all_shapers); j++)
+	if (end - p == (int) strlen (shapers[j].name) &&
+	    0 == strncmp (shapers[j].name, p, end - p))
+	{
+	  /* Reorder this shaper to position i */
+	 struct hb_shaper_pair_t t = shapers[j];
+	 memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));
+	 shapers[i] = t;
+	 i++;
+	}
+
+      if (!*end)
+	break;
+      else
+	p = end + 1;
+    }
+
+    if (!hb_atomic_ptr_cmpexch (&static_shapers, NULL, shapers)) {
+      free (shapers);
+      goto retry;
+    }
+
+#ifdef HAVE_ATEXIT
+    atexit (free_static_shapers); /* First person registers atexit() callback. */
+#endif
   }
 
-  const char *shaper_list[ARRAY_LENGTH (shapers) + 1];
-} static_shaper_list;
+  return shapers;
+}
+
+
+static const char **static_shaper_list;
+
+static
+void free_static_shaper_list (void)
+{
+  free (static_shaper_list);
+}
 
 const char **
 hb_shape_list_shapers (void)
 {
-  return static_shaper_list.shaper_list;
+retry:
+  const char **shaper_list = (const char **) hb_atomic_ptr_get (&static_shaper_list);
+
+  if (unlikely (!shaper_list))
+  {
+    /* Not found; allocate one. */
+    shaper_list = (const char **) calloc (1 + ARRAY_LENGTH (all_shapers), sizeof (const char *));
+    if (unlikely (!shaper_list)) {
+      static const char *nil_shaper_list[] = {NULL};
+      return nil_shaper_list;
+    }
+
+    const hb_shaper_pair_t *shapers = get_shapers ();
+    unsigned int i;
+    for (i = 0; i < ARRAY_LENGTH (all_shapers); i++)
+      shaper_list[i] = shapers[i].name;
+    shaper_list[i] = NULL;
+
+    if (!hb_atomic_ptr_cmpexch (&static_shaper_list, NULL, shaper_list)) {
+      free (shaper_list);
+      goto retry;
+    }
+
+#ifdef HAVE_ATEXIT
+    atexit (free_static_shaper_list); /* First person registers atexit() callback. */
+#endif
+  }
+
+  return shaper_list;
 }
 
+
 hb_bool_t
 hb_shape_full (hb_font_t          *font,
 	       hb_buffer_t        *buffer,
@@ -124,21 +189,22 @@ hb_shape_full (hb_font_t          *font,
   hb_font_make_immutable (font); /* So we can safely cache stuff on it */
 
   if (likely (!shaper_list)) {
-    for (unsigned int i = 0; i < ARRAY_LENGTH (shapers); i++)
+    const hb_shaper_pair_t *shapers = get_shapers ();
+    for (unsigned int i = 0; i < ARRAY_LENGTH (all_shapers); i++)
       if (likely (shapers[i].func (font, buffer, features, num_features)))
-        return TRUE;
+        return true;
   } else {
     while (*shaper_list) {
-      for (unsigned int i = 0; i < ARRAY_LENGTH (shapers); i++)
-	if (0 == strcmp (*shaper_list, shapers[i].name)) {
-	  if (likely (shapers[i].func (font, buffer, features, num_features)))
-	    return TRUE;
+      for (unsigned int i = 0; i < ARRAY_LENGTH (all_shapers); i++)
+	if (0 == strcmp (*shaper_list, all_shapers[i].name)) {
+	  if (likely (all_shapers[i].func (font, buffer, features, num_features)))
+	    return true;
 	  break;
 	}
       shaper_list++;
     }
   }
-  return FALSE;
+  return false;
 }
 
 void