TvInputHal: AOSP refactor on TvInput Hal

Change access modifiers and qualify methods with virtual, to
allow extensions. Add facility for loading customizations
(Extended classes) dynamically.

Change-Id: I9f57792ca8617a4ad95a237f6fe77e38ba304dbd

2 files changed, 160 insertions, 0 deletions

diff --git a/services/libtvextensions/common/ExtensionsLoader.hpp b/services/libtvextensions/common/ExtensionsLoader.hpp
new file mode 100644
index 0000000..010e614
--- /dev/null
+++ b/services/libtvextensions/common/ExtensionsLoader.hpp
@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2013 - 2015, The Linux Foundation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ *       copyright notice, this list of conditions and the following
+ *       disclaimer in the documentation and/or other materials provided
+ *       with the distribution.
+ *     * Neither the name of The Linux Foundation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+ * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <dlfcn.h>
+#include <common/TvInputHalExtensionsCommon.h>
+
+namespace android {
+
+/*
+ * Create strongly-typed objects of type T
+ * If the customization library exists and does contain a "named" constructor,
+ *  invoke and create an instance
+ * Else create the object of type T itself
+ *
+ * Contains a static instance to dlopen'd library, But may end up
+ * opening the library mutiple times. Following snip from dlopen man page is
+ * reassuring "...Only a single copy of an object file is brought into the
+ * address space, even if dlopen() is invoked multiple times in reference to
+ * the file, and even if different pathnames are used to reference the file.."
+ */
+
+template <typename T>
+T *ExtensionsLoader<T>::createInstance(const char *createFunctionName) {
+        ALOGV("createInstance(%dbit) : %s", sizeof(intptr_t)*8, createFunctionName);
+        // create extended object if extensions-lib is available and
+        // TVINPUT_HAL_EXTENSIONS is enabled
+#if ENABLE_TVINPUT_HAL_EXTENSIONS
+        createFunction_t createFunc = loadCreateFunction(createFunctionName);
+        if (createFunc) {
+            return reinterpret_cast<T *>((*createFunc)());
+        }
+#endif
+        // Else, create the default object
+        return new T;
+}
+
+template <typename T>
+void ExtensionsLoader<T>::loadLib() {
+        if (!mLibHandle) {
+            mLibHandle = ::dlopen(CUSTOMIZATION_LIB_NAME, RTLD_LAZY);
+            if (!mLibHandle) {
+                ALOGV("%s", dlerror());
+                return;
+            }
+            ALOGV("Opened %s", CUSTOMIZATION_LIB_NAME);
+        }
+}
+
+template <typename T>
+createFunction_t ExtensionsLoader<T>::loadCreateFunction(const char *createFunctionName) {
+        loadLib();
+        if (!mLibHandle) {
+            return NULL;
+        }
+        createFunction_t func = (createFunction_t)dlsym(mLibHandle, createFunctionName);
+        if (!func) {
+            ALOGW("symbol %s not found:  %s",createFunctionName, dlerror());
+        }
+        return func;
+}
+
+//static
+template <typename T>
+void *ExtensionsLoader<T>::mLibHandle = NULL;
+
+} //namespace android
diff --git a/services/libtvextensions/common/TvInputHalExtensionsCommon.h b/services/libtvextensions/common/TvInputHalExtensionsCommon.h
new file mode 100644
index 0000000..3db4c7b
--- /dev/null
+++ b/services/libtvextensions/common/TvInputHalExtensionsCommon.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2013 - 2015, The Linux Foundation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ *       copyright notice, this list of conditions and the following
+ *       disclaimer in the documentation and/or other materials provided
+ *       with the distribution.
+ *     * Neither the name of The Linux Foundation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+ * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#ifndef _TVINPUTHAL_EXTENSIONS_COMMON_H_
+#define _TVINPUTHAL_EXTENSIONS_COMMON_H_
+
+namespace android {
+
+static const char * CUSTOMIZATION_LIB_NAME = "libTvInputHalEnhancements.so";
+
+typedef void *(*createFunction_t)(void);
+
+template <typename T>
+struct ExtensionsLoader {
+
+    static T *createInstance(const char *createFunctionName);
+
+private:
+    static void loadLib();
+    static createFunction_t loadCreateFunction(const char *createFunctionName);
+    static void *mLibHandle;
+};
+
+/*
+ * Boiler-plate to declare the class as a singleton (with a static getter)
+ * which can be loaded (dlopen'd) via ExtensionsLoader
+ */
+#define DECLARE_LOADABLE_SINGLETON(className)   \
+protected:                                      \
+    className();                                \
+    virtual ~className();                       \
+    static className *sInst;                    \
+private:                                        \
+    className(const className&);                \
+    className &operator=(className &);          \
+public:                                         \
+    static className *get() {                   \
+        return sInst;                           \
+    }                                           \
+    friend struct ExtensionsLoader<className>;
+
+} //namespace android
+
+#endif // _TVINPUTHAL_EXTENSIONS_COMMON_H_