Prevent crash in Lua bindings.

src/utils/SkLua.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkLua.h"
+#include "SkAnnotation.h"
 #include "SkCanvas.h"
 #include "SkData.h"
 #include "SkDocument.h"
 #include "SkImage.h"
 #include "SkMatrix.h"
 #include "SkPaint.h"
 #include "SkPath.h"
 #include "SkPixelRef.h"
 #include "SkRRect.h"
 #include "SkString.h"
 #include "SkTypeface.h"
 
 extern "C" {
     #include "lua.h"
     #include "lualib.h"
     #include "lauxlib.h"
 }
 
 // return the metatable name for a given class
 template <typename T> const char* get_mtname();
 #define DEF_MTNAME(T)                           \
     template <> const char* get_mtname<T>() {   \
         return #T "_LuaMetaTableName";          \
     }
 
+DEF_MTNAME(SkAnnotation)
 DEF_MTNAME(SkCanvas)
 DEF_MTNAME(SkDocument)
 DEF_MTNAME(SkImage)
 DEF_MTNAME(SkMatrix)
 DEF_MTNAME(SkRRect)
 DEF_MTNAME(SkPath)
 DEF_MTNAME(SkPaint)
 DEF_MTNAME(SkShader)
 DEF_MTNAME(SkTypeface)
 
 template <typename T> T* push_new(lua_State* L) {
     T* addr = (T*)lua_newuserdata(L, sizeof(T));
     new (addr) T;
     luaL_getmetatable(L, get_mtname<T>());
     lua_setmetatable(L, -2);
     return addr;
 }
 
 template <typename T> void push_obj(lua_State* L, const T& obj) {
     new (lua_newuserdata(L, sizeof(T))) T(obj);
     luaL_getmetatable(L, get_mtname<T>());
     lua_setmetatable(L, -2);
 }
 
 template <typename T> void push_ref(lua_State* L, T* ref) {
-    *(T**)lua_newuserdata(L, sizeof(T*)) = SkRef(ref);
+    *(T**)lua_newuserdata(L, sizeof(T*)) = SkSafeRef(ref);
     luaL_getmetatable(L, get_mtname<T>());
     lua_setmetatable(L, -2);
 }
 
 template <typename T> T* get_ref(lua_State* L, int index) {
     return *(T**)luaL_checkudata(L, index, get_mtname<T>());
 }
 
 template <typename T> T* get_obj(lua_State* L, int index) {
     return (T*)luaL_checkudata(L, index, get_mtname<T>());
@@ skipping 558 matching lines @@
 static int lpaint_getShader(lua_State* L) {
     const SkPaint* paint = get_obj<SkPaint>(L, 1);
     SkShader* shader = paint->getShader();
     if (shader) {
         push_ref(L, shader);
         return 1;
     }
     return 0;
 }
 
+static int lpaint_getAnnotation(lua_State* L) {
+    const SkPaint* paint = get_obj<SkPaint>(L, 1);
+    SkAnnotation* annotation = paint->getAnnotation();
+    if (annotation) {
+        push_ref(L, annotation);
+        return 1;
+    }
+    return 0;
+}
+
 static int lpaint_gc(lua_State* L) {
     get_obj<SkPaint>(L, 1)->~SkPaint();
     return 0;
 }
 
 static const struct luaL_Reg gSkPaint_Methods[] = {
     { "isAntiAlias", lpaint_isAntiAlias },
     { "setAntiAlias", lpaint_setAntiAlias },
     { "getColor", lpaint_getColor },
     { "setColor", lpaint_setColor },
     { "getTextSize", lpaint_getTextSize },
     { "setTextSize", lpaint_setTextSize },
     { "getTypeface", lpaint_getTypeface },
     { "setTypeface", lpaint_setTypeface },
     { "getFontID", lpaint_getFontID },
     { "getTextAlign", lpaint_getTextAlign },
     { "setTextAlign", lpaint_setTextAlign },
     { "getStroke", lpaint_getStroke },
     { "setStroke", lpaint_setStroke },
     { "getStrokeWidth", lpaint_getStrokeWidth },
     { "setStrokeWidth", lpaint_setStrokeWidth },
     { "measureText", lpaint_measureText },
     { "getFontMetrics", lpaint_getFontMetrics },
     { "getEffects", lpaint_getEffects },
     { "getShader", lpaint_getShader },
+    { "getAnnotation", lpaint_getAnnotation },
     { "__gc", lpaint_gc },
     { NULL, NULL }
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 static const char* mode2string(SkShader::TileMode mode) {
     static const char* gNames[] = { "clamp", "repeat", "mirror" };
     SkASSERT((unsigned)mode < SK_ARRAY_COUNT(gNames));
     return gNames[mode];
@@ skipping 294 matching lines @@
 static const struct luaL_Reg gSkImage_Methods[] = {
     { "width", limage_width },
     { "height", limage_height },
     { "__gc", limage_gc },
     { NULL, NULL }
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 static int ltypeface_gc(lua_State* L) {
-    get_ref<SkTypeface>(L, 1)->unref();
+    SkSafeUnref(get_ref<SkTypeface>(L, 1));

[reed1, 2013/12/17 16:31:50]

I believe you, but this just seems wrong. If we had no typeface, we should have
pushed a NULL up to lua, instead of a lua object wrapping null.

     return 0;
 }
 
 static const struct luaL_Reg gSkTypeface_Methods[] = {
     { "__gc", ltypeface_gc },
     { NULL, NULL }
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
@@ skipping 132 matching lines @@
     REG_CLASS(L, SkShader);
     REG_CLASS(L, SkTypeface);
     REG_CLASS(L, SkMatrix);
 }
 
 extern "C" int luaopen_skia(lua_State* L);
 extern "C" int luaopen_skia(lua_State* L) {
     SkLua::Load(L);
     return 0;
 }