move GraphicEnv from libgui to libui

This breaks a circular dependency between libEGL
and libgui.

Test: compiled and booted a device
Change-Id: I78932bba07fb9ef310d8e1622bd3a47f57e89c45
diff --git a/libs/ui/GraphicsEnv.cpp b/libs/ui/GraphicsEnv.cpp
new file mode 100644
index 0000000..1d20424
--- /dev/null
+++ b/libs/ui/GraphicsEnv.cpp
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//#define LOG_NDEBUG 1
+#define LOG_TAG "GraphicsEnv"
+#include <ui/GraphicsEnv.h>
+
+#include <mutex>
+
+#include <log/log.h>
+#include <nativeloader/dlext_namespaces.h>
+
+namespace android {
+
+/*static*/ GraphicsEnv& GraphicsEnv::getInstance() {
+    static GraphicsEnv env;
+    return env;
+}
+
+void GraphicsEnv::setDriverPath(const std::string path) {
+    if (!mDriverPath.empty()) {
+        ALOGV("ignoring attempt to change driver path from '%s' to '%s'",
+                mDriverPath.c_str(), path.c_str());
+        return;
+    }
+    ALOGV("setting driver path to '%s'", path.c_str());
+    mDriverPath = path;
+}
+
+android_namespace_t* GraphicsEnv::getDriverNamespace() {
+    static std::once_flag once;
+    std::call_once(once, [this]() {
+        // TODO; In the next version of Android, all graphics drivers will be
+        // loaded into a custom namespace. To minimize risk for this release,
+        // only updated drivers use a custom namespace.
+        //
+        // Additionally, the custom namespace will be
+        // ANDROID_NAMESPACE_TYPE_ISOLATED, and will only have access to a
+        // subset of the system.
+        if (mDriverPath.empty())
+            return;
+
+        char defaultPath[PATH_MAX];
+        android_get_LD_LIBRARY_PATH(defaultPath, sizeof(defaultPath));
+        size_t defaultPathLen = strlen(defaultPath);
+
+        std::string path;
+        path.reserve(mDriverPath.size() + 1 + defaultPathLen);
+        path.append(mDriverPath);
+        path.push_back(':');
+        path.append(defaultPath, defaultPathLen);
+
+        mDriverNamespace = android_create_namespace(
+                "gfx driver",
+                nullptr,                    // ld_library_path
+                path.c_str(),               // default_library_path
+                ANDROID_NAMESPACE_TYPE_SHARED,
+                nullptr,                    // permitted_when_isolated_path
+                nullptr);                   // parent
+    });
+    return mDriverNamespace;
+}
+
+} // namespace android
+
+extern "C" android_namespace_t* android_getDriverNamespace() {
+    return android::GraphicsEnv::getInstance().getDriverNamespace();
+}