Add support for Unicorn 1.0.2's uc_context_free

.travis.yml

@@ -4,7 +4,7 @@ language: cpp
 
 env:
   global:
-    - UNICORN_VERSION=1.0.1
+    - UNICORN_VERSION=1.0.2
   matrix:
     - LUA_VERSION=5.1
     - LUA_VERSION=5.2

CHANGELOG.rst

@@ -1,8 +1,19 @@
 Changes
 =======
 
-1.0 (2021-01-18)
-----------------
+1.1.0 (2021-01-18)
+------------------
+
+New Features
+~~~~~~~~~~~~
+
+* Added support for Unicorn 1.0.2.
+* Context objects now have an instance method, ``free()`` which can be used to
+  release the context's resources.
+
+
+1.0.0 (2021-01-18)
+------------------
 
 **First stable release!**
 

docs/api.rst

@@ -372,6 +372,19 @@ Arguments
 ``values``: A table mapping register IDs to the values to write to those registers.
 
 
+Contexts
+--------
+
+``free()``
+~~~~~~~~~~
+
+Release the resources of this context object. It can no longer be used.
+Note: (This still works correctly if the library is compiled against Unicorn
+1.0.1 and older, before Unicorn added ``uc_context_free()``.)
+
+*New in 1.1.0*
+
+
 Global Functions
 ----------------
 

include/unicornlua/context.h

@@ -14,6 +14,7 @@
 
 extern const char * const kContextMetatableName;
 extern const luaL_Reg kContextMetamethods[];
+extern const luaL_Reg kContextInstanceMethods[];
 
 
 class Context {
@@ -40,6 +41,13 @@ class Context {
 int ul_context_save(lua_State *L);
 int ul_context_restore(lua_State *L);
 
+/** Deallocate a context object.
+ *
+ * This function calls `uc_free()` on versions of Unicorn before 1.0.2, and calls
+ * `uc_context_free()` on 1.0.2+. In either case, it will behave as expected.
+ */
+int ul_context_free(lua_State *L);
+
 
 #define get_context_struct(L, index)   \
     reinterpret_cast<Context *>(luaL_checkudata((L), (index), kContextMetatableName))

include/unicornlua/engine.h

@@ -47,6 +47,9 @@ class UCLuaEngine {
      * there's no reason to keep a context around once it's no longer used inside Lua.
      * Thus, there isn't really any use in allowing a @ref Context to be created in the
      * heap.
+     *
+     * Changed in 1.1.0: This now automatically saves the engine state in the context.
+     * Before, it was necessary to call `update()` on the returned context object.
      */
     Context *create_context_in_lua();
     void restore_from_context(Context *context);

include/unicornlua/unicornlua.h

@@ -17,4 +17,7 @@
     #error "Library must be compiled against version 1.x of Unicorn."
 #endif
 
+
+#define UNICORNLUA_UNICORN_MAJOR_MINOR_PATCH    ((UC_VERSION_MAJOR << 16) | (UC_VERSION_MINOR << 8) | UC_VERSION_EXTRA)
+
 #endif  /* INCLUDE_UNICORNLUA_UNICORNLUA_H_ */

src/context.cpp

@@ -22,6 +22,12 @@ const luaL_Reg kContextMetamethods[] = {
 };
 
 
+const luaL_Reg kContextInstanceMethods[] = {
+    {"free", call_release},
+    {nullptr, nullptr}
+};
+
+
 Context::Context(UCLuaEngine& engine, uc_context *context)
     : engine_(engine), context_(context) {}
 
@@ -55,7 +61,21 @@ void Context::update() {
 
 
 void Context::release() {
-    uc_err error = uc_free(context_);
+    uc_err error;
+
+    if (context_ == nullptr)
+        throw LuaBindingError(
+            "Attempted to free a context object that has already been freed."
+        );
+
+    #if UNICORNLUA_UNICORN_MAJOR_MINOR_PATCH >= 0x010002
+        /* Unicorn 1.0.2 added its own separate function for freeing contexts. */
+        error = uc_context_free(context_);
+    #else
+        /* Unicorn 1.0.1 and lower uses uc_free(). */
+        error = uc_free(context_);
+    #endif
+
     context_ = nullptr;
     if (error != UC_ERR_OK)
         throw UnicornLibraryError(error);
@@ -76,10 +96,10 @@ int ul_context_save(lua_State *L) {
         // so we can return it to the caller.
         context = engine->create_context_in_lua();
     }
-    else
+    else {
         context = get_context_struct(L, 2);
-
-    context->update();
+        context->update();
+    }
     return 1;
 }
 
@@ -91,3 +111,11 @@ int ul_context_restore(lua_State *L) {
     engine->restore_from_context(context);
     return 0;
 }
+
+
+int ul_context_free(lua_State *L) {
+    auto context = get_context_struct(L, 1);
+
+    context->release();
+    return 0;
+}

src/engine.cpp

@@ -123,12 +123,19 @@ Context *UCLuaEngine::create_context_in_lua() {
     new (context) Context(*this);
 
     luaL_setmetatable(L, kContextMetatableName);
+    context->update();
     return context;
 }
 
 
 void UCLuaEngine::restore_from_context(Context *context) {
-    uc_err error = uc_context_restore(engine, context->get_handle());
+    auto handle = context->get_handle();
+    if (handle == nullptr)
+        throw LuaBindingError(
+            "Attempted to use a context object that has already been freed."
+        );
+
+    uc_err error = uc_context_restore(engine, handle);
     if (error != UC_ERR_OK)
         throw UnicornLibraryError(error);
 }
@@ -149,6 +156,11 @@ void ul_init_engines_lib(lua_State *L) {
 
     luaL_newmetatable(L, kContextMetatableName);
     luaL_setfuncs(L, kContextMetamethods, 0);
+
+    lua_newtable(L);
+    luaL_setfuncs(L, kContextInstanceMethods, 0);
+    lua_setfield(L, -2, "__index");
+
     lua_pop(L, 2);
 }
 

tests/c/engine.cpp

@@ -46,42 +46,3 @@ TEST_CASE_FIXTURE(AutoclosingEngineFixture, "errno() on clean engine works") {
 }
 
 // TODO (dargueta): Force the engine into a bad state to verify ::get_errno()
-
-
-TEST_CASE_FIXTURE(AutoclosingEngineFixture, "Test creating a context") {
-    Context *context = uclua_engine->create_context_in_lua();
-    CHECK_NE(context, nullptr);
-
-    CHECK_MESSAGE(
-        lua_gettop(L) == 1, "Expecting a context object on the stack."
-    );
-    CHECK_MESSAGE(
-        lua_type(L, 1) == LUA_TUSERDATA, "Object at top of stack should be userdata."
-    );
-
-    CHECK_MESSAGE(
-        lua_touserdata(L, 1) == context,
-        "TOS isn't the context object we were expecting."
-    );
-
-    // Metatable of the context is at index 2, the expected metatable is at index 3.
-    CHECK_MESSAGE(
-        lua_getmetatable(L, 1) != 0, "Context object has no metatable."
-    );
-    luaL_getmetatable(L, kContextMetatableName);
-
-    CHECK(lua_gettop(L) == 3);
-
-#if LUA_VERSION_NUM < 502
-    // lua_compare() was added in 5.2, so we have to use lua_equal() here.
-    CHECK_MESSAGE(
-        lua_equal(L, 2, 3) == 1,
-        "Context metatable doesn't match the expected one."
-    );
-#else
-    CHECK_MESSAGE(
-        lua_compare(L, 2, 3, LUA_OPEQ) == 1,
-        "Context metatable doesn't match the expected one."
-    );
-#endif
-}