Add native C APIs for working with the Asset Manager

Change-Id: I493b142c4b35e5cc1a1e85283bb5dfb306a6d261

2 files changed, 211 insertions, 0 deletions

diff --git a/native/android/Android.mk b/native/android/Android.mk
index 2fe0679..950a1e9 100644
--- a/native/android/Android.mk
+++ b/native/android/Android.mk
@@ -6,6 +6,7 @@ include $(CLEAR_VARS)
 # our source files
 #
 LOCAL_SRC_FILES:= \
+    asset_manager.cpp \
     input.cpp \
     looper.cpp \
     native_activity.cpp \
diff --git a/native/android/asset_manager.cpp b/native/android/asset_manager.cpp
new file mode 100644
index 0000000..36c381e
--- /dev/null
+++ b/native/android/asset_manager.cpp
@@ -0,0 +1,210 @@
+/*
+ * Copyright (C) 2010 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_TAG "NAsset"
+#include <utils/Log.h>
+
+#include <android/asset_manager.h>
+#include <utils/AssetManager.h>
+#include <utils/AssetDir.h>
+#include <utils/Asset.h>
+#include <utils/threads.h>
+
+#include "jni.h"
+#include "JNIHelp.h"
+
+using namespace android;
+
+// -------------------- Backing implementation of the public API --------------------
+
+// AAssetManager is actually a secret typedef for an empty base class of AssetManager,
+// but AAssetDir and AAsset are actual wrappers for isolation.
+
+// -----
+struct AAssetDir {
+    AssetDir* mAssetDir;
+    size_t mCurFileIndex;
+    String8 mCachedFileName;
+
+    AAssetDir(AssetDir* dir) : mAssetDir(dir), mCurFileIndex(0) { }
+    ~AAssetDir() { delete mAssetDir; }
+};
+
+
+// -----
+struct AAsset {
+    Asset* mAsset;
+
+    AAsset(Asset* asset) : mAsset(asset) { }
+    ~AAsset() { delete mAsset; }
+};
+
+// -------------------- Public native C API --------------------
+
+/**
+ * Supporting information
+ */
+
+static struct assetmanager_offsets_t
+{
+    jfieldID mObject;
+} gAssetManagerOffsets;
+
+static volatile bool gJNIConfigured = false;
+static Mutex gMutex;
+
+/**
+ * Asset Manager functionality
+ */
+AAssetManager* AAssetManager_fromJava(JNIEnv* env, jobject assetManager)
+{
+    {
+        Mutex::Autolock _l(gMutex);
+
+        if (gJNIConfigured == false) {
+            jclass amClass = env->FindClass("android/content/res/AssetManager");
+            gAssetManagerOffsets.mObject = env->GetFieldID(amClass, "mObject", "I");
+            gJNIConfigured = true;
+        }
+    }
+
+    return (AAssetManager*) env->GetIntField(assetManager, gAssetManagerOffsets.mObject);
+}
+
+AAsset* AAssetManager_open(AAssetManager* amgr, const char* filename, int mode)
+{
+    Asset::AccessMode amMode;
+    switch (mode) {
+    case AASSET_MODE_UNKNOWN:
+        amMode = Asset::ACCESS_UNKNOWN;
+        break;
+    case AASSET_MODE_RANDOM:
+        amMode = Asset::ACCESS_RANDOM;
+        break;
+    case AASSET_MODE_STREAMING:
+        amMode = Asset::ACCESS_STREAMING;
+        break;
+    case AASSET_MODE_BUFFER:
+        amMode = Asset::ACCESS_BUFFER;
+        break;
+    default:
+        return NULL;
+    }
+
+    AssetManager* mgr = static_cast<AssetManager*>(amgr);
+    Asset* asset = mgr->open(filename, amMode);
+    if (asset == NULL) {
+        return NULL;
+    }
+
+    return new AAsset(asset);
+}
+
+AAssetDir* AAssetManager_openDir(AAssetManager* amgr, const char* dirName)
+{
+    AssetManager* mgr = static_cast<AssetManager*>(amgr);
+    return new AAssetDir(mgr->openDir(dirName));
+}
+
+/**
+ * AssetDir functionality
+ */
+
+const char* AAssetDir_getNextFileName(AAssetDir* assetDir)
+{
+    const char* returnName = NULL;
+    size_t index = assetDir->mCurFileIndex;
+    const size_t max = assetDir->mAssetDir->getFileCount();
+
+    // Find the next regular file; explicitly don't report directories even if the
+    // underlying implementation changes to report them.  At that point we can add
+    // a more general iterator to this native interface set if appropriate.
+    while ((index < max) && (assetDir->mAssetDir->getFileType(index) != kFileTypeRegular)) {
+        index++;
+    }
+
+    // still in bounds? then the one at 'index' is the next to be reported; generate
+    // the string to return and advance the iterator for next time.
+    if (index < max) {
+        assetDir->mCachedFileName = assetDir->mAssetDir->getFileName(index);
+        returnName = assetDir->mCachedFileName.string();
+        index++;
+    }
+
+    assetDir->mCurFileIndex = index;
+    return returnName;
+}
+
+void AAssetDir_rewind(AAssetDir* assetDir)
+{
+    assetDir->mCurFileIndex = 0;
+}
+
+const char* AAssetDir_getFileName(AAssetDir* assetDir, int index)
+{
+    assetDir->mCachedFileName = assetDir->mAssetDir->getFileName(index);
+    return assetDir->mCachedFileName.string();
+}
+
+void AAssetDir_close(AAssetDir* assetDir)
+{
+    delete assetDir;
+}
+
+/**
+ * Asset functionality
+ */
+
+int AAsset_read(AAsset* asset, void* buf, size_t count)
+{
+    return asset->mAsset->read(buf, (size_t)count);
+}
+
+off_t AAsset_seek(AAsset* asset, off_t offset, int whence)
+{
+    return asset->mAsset->seek(offset, whence);
+}
+
+void AAsset_close(AAsset* asset)
+{
+    asset->mAsset->close();
+    delete asset;
+}
+
+const void* AAsset_getBuffer(AAsset* asset)
+{
+    return asset->mAsset->getBuffer(false);
+}
+
+off_t AAsset_getLength(AAsset* asset)
+{
+    return asset->mAsset->getLength();
+}
+
+off_t AAsset_getRemainingLength(AAsset* asset)
+{
+    return asset->mAsset->getRemainingLength();
+}
+
+int AAsset_openFileDescriptor(AAsset* asset, off_t* outStart, off_t* outLength)
+{
+    return asset->mAsset->openFileDescriptor(outStart, outLength);
+}
+
+int AAsset_isAllocated(AAsset* asset)
+{
+    return asset->mAsset->isAllocated() ? 1 : 0;
+}