Helper API cleanup.  Allows multiple helpers to function,
because they'll always go in the same order, and this lets
us not have to write headers to keep them paired.
diff --git a/core/jni/android_backup_FileBackupHelperBase.cpp b/core/jni/android_backup_FileBackupHelperBase.cpp
new file mode 100644
index 0000000..8225a36
--- /dev/null
+++ b/core/jni/android_backup_FileBackupHelperBase.cpp
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2009 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 "FileBackupHelper_native"
+#include <utils/Log.h>
+
+#include "JNIHelp.h"
+#include <android_runtime/AndroidRuntime.h>
+
+#include <utils/BackupHelpers.h>
+
+namespace android
+{
+
+// java.io.FileDescriptor
+static jfieldID s_descriptorField = 0;
+
+static int
+ctor(JNIEnv* env, jobject clazz)
+{
+    return (int)new RestoreHelperBase();
+}
+
+static void
+dtor(JNIEnv* env, jobject clazz, jint ptr)
+{
+    delete (RestoreHelperBase*)ptr;
+}
+
+static int
+performBackup_native(JNIEnv* env, jobject clazz, jobject oldState, int data,
+        jobject newState, jobjectArray files, jobjectArray keys)
+{
+    int err;
+
+    // all parameters have already been checked against null
+    int oldStateFD = oldState != NULL ? env->GetIntField(oldState, s_descriptorField) : -1;
+    int newStateFD = env->GetIntField(newState, s_descriptorField);
+    BackupDataWriter* dataStream = (BackupDataWriter*)data;
+
+    const int fileCount = env->GetArrayLength(files);
+    char const** filesUTF = (char const**)malloc(sizeof(char*)*fileCount);
+    for (int i=0; i<fileCount; i++) {
+        filesUTF[i] = env->GetStringUTFChars((jstring)env->GetObjectArrayElement(files, i), NULL);
+    }
+
+    const int keyCount = env->GetArrayLength(keys);
+    char const** keysUTF = (char const**)malloc(sizeof(char*)*keyCount);
+    for (int i=0; i<keyCount; i++) {
+        keysUTF[i] = env->GetStringUTFChars((jstring)env->GetObjectArrayElement(keys, i), NULL);
+    }
+
+    err = back_up_files(oldStateFD, dataStream, newStateFD, filesUTF, keysUTF, fileCount);
+
+    for (int i=0; i<fileCount; i++) {
+        env->ReleaseStringUTFChars((jstring)env->GetObjectArrayElement(files, i), filesUTF[i]);
+    }
+    free(filesUTF);
+
+    for (int i=0; i<keyCount; i++) {
+        env->ReleaseStringUTFChars((jstring)env->GetObjectArrayElement(keys, i), keysUTF[i]);
+    }
+    free(keysUTF);
+
+    return err;
+}
+
+
+static int
+writeFile_native(JNIEnv* env, jobject clazz, jint ptr, jstring filenameObj, int backupReaderPtr)
+{
+    int err;
+    RestoreHelperBase* restore = (RestoreHelperBase*)ptr;
+    BackupDataReader* reader = (BackupDataReader*)backupReaderPtr;
+    char const* filename;
+
+    filename = env->GetStringUTFChars(filenameObj, NULL);
+
+    err = restore->WriteFile(String8(filename), reader);
+
+    env->ReleaseStringUTFChars(filenameObj, filename);
+
+    return err;
+}
+
+static int
+writeSnapshot_native(JNIEnv* env, jobject clazz, jint ptr, jobject fileDescriptor)
+{
+    int err;
+
+    RestoreHelperBase* restore = (RestoreHelperBase*)ptr;
+    int fd = env->GetIntField(fileDescriptor, s_descriptorField);
+
+    err = restore->WriteSnapshot(fd);
+
+    return err;
+}
+
+static const JNINativeMethod g_methods[] = {
+    { "ctor", "()I", (void*)ctor },
+    { "dtor", "(I)V", (void*)dtor },
+    { "performBackup_native",
+       "(Ljava/io/FileDescriptor;ILjava/io/FileDescriptor;[Ljava/lang/String;[Ljava/lang/String;)I",
+       (void*)performBackup_native },
+    { "writeFile_native", "(ILjava/lang/String;I)I", (void*)writeFile_native },
+    { "writeSnapshot_native", "(ILjava/io/FileDescriptor;)I", (void*)writeSnapshot_native },
+};
+
+int register_android_backup_FileBackupHelperBase(JNIEnv* env)
+{
+    jclass clazz;
+
+    clazz = env->FindClass("java/io/FileDescriptor");
+    LOG_FATAL_IF(clazz == NULL, "Unable to find class java.io.FileDescriptor");
+    s_descriptorField = env->GetFieldID(clazz, "descriptor", "I");
+    LOG_FATAL_IF(s_descriptorField == NULL,
+            "Unable to find descriptor field in java.io.FileDescriptor");
+    
+    return AndroidRuntime::registerNativeMethods(env, "android/backup/FileBackupHelperBase",
+            g_methods, NELEM(g_methods));
+}
+
+}