New APIs for MTP and PTP host support

This replaces the previous ContentProvider based interface

Change-Id: I4cea2544854adb9fdcc04345e4d73d8ef05380f3
Signed-off-by: Mike Lockwood <lockwood@android.com>

13 files changed, 1715 insertions, 332 deletions

diff --git a/media/java/android/mtp/MtpClient.java b/media/java/android/mtp/MtpClient.java
new file mode 100644
index 0000000..19ee92a
--- /dev/null
+++ b/media/java/android/mtp/MtpClient.java
@@ -0,0 +1,270 @@
+/*
+ * 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.
+ */
+
+package android.mtp;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.hardware.UsbConstants;
+import android.hardware.UsbDevice;
+import android.hardware.UsbInterface;
+import android.hardware.UsbManager;
+import android.os.ParcelFileDescriptor;
+import android.util.Log;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * This class helps an application manage a list of connected MTP devices.
+ * It listens for MTP devices being attached and removed from the USB host bus
+ * and notifies the application when the MTP device list changes.
+ * {@hide}
+ */
+public class MtpClient {
+
+    private static final String TAG = "MtpClient";
+
+    private final Context mContext;
+    private final UsbManager mUsbManager;
+    private final ArrayList<Listener> mListeners = new ArrayList<Listener>();
+    private final ArrayList<MtpDevice> mDeviceList = new ArrayList<MtpDevice>();
+
+    private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            String deviceName = intent.getStringExtra(UsbManager.EXTRA_DEVICE_NAME);
+
+            synchronized (mDeviceList) {
+                MtpDevice mtpDevice = getDeviceLocked(deviceName);
+
+                if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(intent.getAction())) {
+                    if (mtpDevice == null) {
+                        UsbDevice usbDevice =
+                                (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
+                        mtpDevice = openDevice(usbDevice);
+                    }
+                    if (mtpDevice != null) {
+                        mDeviceList.add(mtpDevice);
+                        for (Listener listener : mListeners) {
+                            listener.deviceAdded(mtpDevice);
+                        }
+                    }
+                } else if (mtpDevice != null) {
+                    mDeviceList.remove(mtpDevice);
+                    for (Listener listener : mListeners) {
+                        listener.deviceRemoved(mtpDevice);
+                    }
+                }
+            }
+        }
+    };
+
+    public interface Listener {
+        public void deviceAdded(MtpDevice device);
+        public void deviceRemoved(MtpDevice device);
+    }
+
+   static public boolean isCamera(UsbDevice device) {
+        int count = device.getInterfaceCount();
+        for (int i = 0; i < count; i++) {
+            UsbInterface intf = device.getInterface(i);
+            if (intf.getInterfaceClass() == UsbConstants.USB_CLASS_STILL_IMAGE &&
+                    intf.getInterfaceSubclass() == 1 &&
+                    intf.getInterfaceProtocol() == 1) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private MtpDevice openDevice(UsbDevice usbDevice) {
+        if (isCamera(usbDevice)) {
+            MtpDevice mtpDevice = new MtpDevice(usbDevice);
+            if (mtpDevice.open(mUsbManager)) {
+                return mtpDevice;
+            }
+        }
+        return null;
+    }
+
+    public MtpClient(Context context) {
+        mContext = context;
+        mUsbManager = (UsbManager)context.getSystemService(Context.USB_SERVICE);
+
+        IntentFilter filter = new IntentFilter();
+        filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
+        filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
+        context.registerReceiver(mUsbReceiver, filter);
+
+        for (UsbDevice usbDevice : mUsbManager.getDeviceList().values()) {
+            MtpDevice mtpDevice = getDeviceLocked(usbDevice.getDeviceName());
+            if (mtpDevice == null) {
+                mtpDevice = openDevice(usbDevice);
+            }
+            if (mtpDevice != null) {
+                mDeviceList.add(mtpDevice);
+            }
+        }
+    }
+
+    public void close() {
+        mContext.unregisterReceiver(mUsbReceiver);
+    }
+
+    @Override
+    protected void finalize() throws Throwable {
+        try {
+            close();
+        } finally {
+            super.finalize();
+        }
+    }
+
+    public void addListener(Listener listener) {
+        synchronized (mDeviceList) {
+            if (!mListeners.contains(listener)) {
+                mListeners.add(listener);
+            }
+        }
+    }
+
+    public void removeListener(Listener listener) {
+        synchronized (mDeviceList) {
+            mListeners.remove(listener);
+        }
+    }
+
+    public MtpDevice getDevice(String deviceName) {
+        synchronized (mDeviceList) {
+            return getDeviceLocked(deviceName);
+        }
+    }
+
+    public MtpDevice getDevice(int id) {
+        synchronized (mDeviceList) {
+            return getDeviceLocked(UsbDevice.getDeviceName(id));
+        }
+    }
+
+    private MtpDevice getDeviceLocked(String deviceName) {
+        for (MtpDevice device : mDeviceList) {
+            if (device.getDeviceName().equals(deviceName)) {
+                return device;
+            }
+        }
+        return null;
+    }
+
+    public List<MtpDevice> getDeviceList() {
+        synchronized (mDeviceList) {
+            return new ArrayList<MtpDevice>(mDeviceList);
+        }
+    }
+
+    public List<MtpStorageInfo> getStorageList(String deviceName) {
+        MtpDevice device = getDevice(deviceName);
+        if (device == null) {
+            return null;
+        }
+        int[] storageIds = device.getStorageIds();
+        if (storageIds == null) {
+            return null;
+        }
+
+        int length = storageIds.length;
+        ArrayList<MtpStorageInfo> storageList = new ArrayList<MtpStorageInfo>(length);
+        for (int i = 0; i < length; i++) {
+            MtpStorageInfo info = device.getStorageInfo(storageIds[i]);
+            if (info == null) {
+                Log.w(TAG, "getStorageInfo failed");
+            } else {
+                storageList.add(info);
+            }
+        }
+        return storageList;
+    }
+
+    public MtpObjectInfo getObjectInfo(String deviceName, int objectHandle) {
+        MtpDevice device = getDevice(deviceName);
+        if (device == null) {
+            return null;
+        }
+        return device.getObjectInfo(objectHandle);
+    }
+
+    public boolean deleteObject(String deviceName, int objectHandle) {
+        MtpDevice device = getDevice(deviceName);
+        if (device == null) {
+            return false;
+        }
+        return device.deleteObject(objectHandle);
+    }
+
+    public List<MtpObjectInfo> getObjectList(String deviceName, int storageId, int objectHandle) {
+        MtpDevice device = getDevice(deviceName);
+        if (device == null) {
+            return null;
+        }
+        if (objectHandle == 0) {
+            // all objects in root of storage
+            objectHandle = 0xFFFFFFFF;
+        }
+        int[] handles = device.getObjectHandles(storageId, 0, objectHandle);
+        if (handles == null) {
+            return null;
+        }
+
+        int length = handles.length;
+        ArrayList<MtpObjectInfo> objectList = new ArrayList<MtpObjectInfo>(length);
+        for (int i = 0; i < length; i++) {
+            MtpObjectInfo info = device.getObjectInfo(handles[i]);
+            if (info == null) {
+                Log.w(TAG, "getObjectInfo failed");
+            } else {
+                objectList.add(info);
+            }
+        }
+        return objectList;
+    }
+
+    public byte[] getObject(String deviceName, int objectHandle, int objectSize) {
+        MtpDevice device = getDevice(deviceName);
+        if (device == null) {
+            return null;
+        }
+        return device.getObject(objectHandle, objectSize);
+    }
+
+    public byte[] getThumbnail(String deviceName, int objectHandle) {
+        MtpDevice device = getDevice(deviceName);
+        if (device == null) {
+            return null;
+        }
+        return device.getThumbnail(objectHandle);
+    }
+
+    public boolean importFile(String deviceName, int objectHandle, String destPath) {
+        MtpDevice device = getDevice(deviceName);
+        if (device == null) {
+            return false;
+        }
+        return device.importFile(objectHandle, destPath);
+    }
+}
diff --git a/media/java/android/mtp/MtpDevice.java b/media/java/android/mtp/MtpDevice.java
new file mode 100644
index 0000000..2d726c2
--- /dev/null
+++ b/media/java/android/mtp/MtpDevice.java
@@ -0,0 +1,141 @@
+/*
+ * 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.
+ */
+
+package android.mtp;
+
+import android.hardware.UsbDevice;
+import android.hardware.UsbManager;
+import android.os.ParcelFileDescriptor;
+import android.util.Log;
+
+/**
+ * This class represents an MTP device connected on the USB host bus.
+ *
+ * {@hide}
+ */
+public final class MtpDevice {
+
+    private static final String TAG = "MtpDevice";
+
+    private final UsbDevice mDevice;
+
+    static {
+        System.loadLibrary("media_jni");
+    }
+
+    public MtpDevice(UsbDevice device) {
+        mDevice = device;
+    }
+
+    public boolean open(UsbManager manager) {
+        if (manager.openDevice(mDevice)) {
+            return native_open(mDevice.getDeviceName(), mDevice.getFileDescriptor());
+        } else {
+            return false;
+        }
+    }
+
+    public void close() {
+        Log.d(TAG, "close");
+        native_close();
+    }
+
+    @Override
+    protected void finalize() throws Throwable {
+        Log.d(TAG, "finalize");
+        try {
+            native_close();
+        } finally {
+            super.finalize();
+        }
+    }
+
+    public String getDeviceName() {
+        return mDevice.getDeviceName();
+    }
+
+    public int getDeviceId() {
+        return mDevice.getDeviceId();
+    }
+
+    @Override
+    public String toString() {
+        return mDevice.getDeviceName();
+    }
+
+    public MtpDeviceInfo getDeviceInfo() {
+        return native_get_device_info();
+    }
+
+    public int[] getStorageIds() {
+        return native_get_storage_ids();
+    }
+
+    public int[] getObjectHandles(int storageId, int format, int objectHandle) {
+        return native_get_object_handles(storageId, format, objectHandle);
+    }
+
+    public byte[] getObject(int objectHandle, int objectSize) {
+        return native_get_object(objectHandle, objectSize);
+    }
+
+    public byte[] getThumbnail(int objectHandle) {
+        return native_get_thumbnail(objectHandle);
+    }
+
+    public MtpStorageInfo getStorageInfo(int storageId) {
+        return native_get_storage_info(storageId);
+    }
+
+    public MtpObjectInfo getObjectInfo(int objectHandle) {
+        return native_get_object_info(objectHandle);
+    }
+
+    public boolean deleteObject(int objectHandle) {
+        return native_delete_object(objectHandle);
+    }
+
+    public long getParent(int objectHandle) {
+        return native_get_parent(objectHandle);
+    }
+
+    public long getStorageID(int objectHandle) {
+        return native_get_storage_id(objectHandle);
+    }
+
+    // Reads a file from device to host to the specified destination.
+    // Returns true if the transfer succeeds.
+    public boolean importFile(int objectHandle, String destPath) {
+        return native_import_file(objectHandle, destPath);
+    }
+
+    // used by the JNI code
+    private int mNativeContext;
+
+    private native boolean native_open(String deviceName, int fd);
+    private native void native_close();
+    private native MtpDeviceInfo native_get_device_info();
+    private native int[] native_get_storage_ids();
+    private native MtpStorageInfo native_get_storage_info(int storageId);
+    private native int[] native_get_object_handles(int storageId, int format, int objectHandle);
+    private native MtpObjectInfo native_get_object_info(int objectHandle);
+    private native byte[] native_get_object(int objectHandle, int objectSize);
+    private native byte[] native_get_thumbnail(int objectHandle);
+    private native boolean native_delete_object(int objectHandle);
+    private native long native_get_parent(int objectHandle);
+    private native long native_get_storage_id(int objectHandle);
+    private native boolean native_import_file(int objectHandle, String destPath);
+}
diff --git a/media/java/android/mtp/MtpDeviceInfo.java b/media/java/android/mtp/MtpDeviceInfo.java
new file mode 100644
index 0000000..d918c20
--- /dev/null
+++ b/media/java/android/mtp/MtpDeviceInfo.java
@@ -0,0 +1,72 @@
+/*
+ * 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.
+ */
+
+package android.mtp;
+
+/**
+ * This class encapsulates information about an MTP device.
+ * This corresponds to the DeviceInfo Dataset described in
+ * section 5.1.1 of the MTP specification.
+ *
+ * {@hide}
+ */
+public class MtpDeviceInfo {
+
+    private String mManufacturer;
+    private String mModel;
+    private String mVersion;
+    private String mSerialNumber;
+
+    // only instantiated via JNI
+    private MtpDeviceInfo() {
+    }
+
+    /**
+     * Returns the manufacturer's name for the MTP device
+     *
+     * @return the manufacturer name
+     */
+    public final String getManufacturer() {
+        return mManufacturer;
+    }
+
+    /**
+     * Returns the model name for the MTP device
+     *
+     * @return the model name
+     */
+    public final String getModel() {
+        return mModel;
+    }
+
+    /**
+     * Returns the version string the MTP device
+     *
+     * @return the device version
+     */
+    public final String getVersion() {
+        return mVersion;
+    }
+
+    /**
+     * Returns the unique serial number for the MTP device
+     *
+     * @return the serial number
+     */
+    public final String getSerialNumber() {
+        return mSerialNumber;
+    }
+}
\ No newline at end of file
diff --git a/media/java/android/mtp/MtpObjectInfo.java b/media/java/android/mtp/MtpObjectInfo.java
new file mode 100644
index 0000000..309d524
--- /dev/null
+++ b/media/java/android/mtp/MtpObjectInfo.java
@@ -0,0 +1,257 @@
+/*
+ * 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.
+ */
+
+package android.mtp;
+
+/**
+ * This class encapsulates information about an object on an MTP device.
+ * This corresponds to the ObjectInfo Dataset described in
+ * section 5.3.1 of the MTP specification.
+ *
+ * {@hide}
+ */
+public final class MtpObjectInfo {
+    private int mHandle;
+    private int mStorageId;
+    private int mFormat;
+    private int mProtectionStatus;
+    private int mCompressedSize;
+    private int mThumbFormat;
+    private int mThumbCompressedSize;
+    private int mThumbPixWidth;
+    private int mThumbPixHeight;
+    private int mImagePixWidth;
+    private int mImagePixHeight;
+    private int mImagePixDepth;
+    private int mParent;
+    private int mAssociationType;
+    private int mAssociationDesc;
+    private int mSequenceNumber;
+    private String mName;
+    private long mDateCreated;
+    private long mDateModified;
+    private String mKeywords;
+
+    // only instantiated via JNI
+    private MtpObjectInfo() {
+    }
+
+    /**
+     * Returns the object handle for the MTP object
+     *
+     * @return the object handle
+     */
+    public final int getObjectHandle() {
+        return mHandle;
+    }
+
+    /**
+     * Returns the storage ID for the MTP object's storage unit
+     *
+     * @return the storage ID
+     */
+    public final int getStorageId() {
+        return mStorageId;
+    }
+
+    /**
+     * Returns the format code for the MTP object
+     *
+     * @return the format code
+     */
+    public final int getFormat() {
+        return mFormat;
+    }
+
+    /**
+     * Returns the protection status for the MTP object
+     * Possible values are:
+     *
+     * <ul>
+     * <li> {@link android.mtp.MtpConstants#PROTECTION_STATUS_NONE}
+     * <li> {@link android.mtp.MtpConstants#PROTECTION_STATUS_READ_ONLY}
+     * <li> {@link android.mtp.MtpConstants#PROTECTION_STATUS_NON_TRANSFERABLE_DATA}
+     * </ul>
+     *
+     * @return the protection status
+     */
+    public final int getProtectionStatus() {
+        return mProtectionStatus;
+    }
+
+    /**
+     * Returns the size of the MTP object
+     *
+     * @return the object size
+     */
+    public final int getCompressedSize() {
+        return mCompressedSize;
+    }
+
+    /**
+     * Returns the format code for the MTP object's thumbnail
+     * Will be zero for objects with no thumbnail
+     *
+     * @return the thumbnail format code
+     */
+    public final int getThumbFormat() {
+        return mThumbFormat;
+    }
+
+    /**
+     * Returns the size of the MTP object's thumbnail
+     * Will be zero for objects with no thumbnail
+     *
+     * @return the thumbnail size
+     */
+    public final int getThumbCompressedSize() {
+        return mThumbCompressedSize;
+    }
+
+    /**
+     * Returns the width of the MTP object's thumbnail in pixels
+     * Will be zero for objects with no thumbnail
+     *
+     * @return the thumbnail width
+     */
+    public final int getThumbPixWidth() {
+        return mThumbPixWidth;
+    }
+
+    /**
+     * Returns the height of the MTP object's thumbnail in pixels
+     * Will be zero for objects with no thumbnail
+     *
+     * @return the thumbnail height
+     */
+    public final int getThumbPixHeight() {
+        return mThumbPixHeight;
+    }
+
+    /**
+     * Returns the width of the MTP object in pixels
+     * Will be zero for non-image objects
+     *
+     * @return the image width
+     */
+    public final int getImagePixWidth() {
+        return mImagePixWidth;
+    }
+
+    /**
+     * Returns the height of the MTP object in pixels
+     * Will be zero for non-image objects
+     *
+     * @return the image height
+     */
+    public final int getImagePixHeight() {
+        return mImagePixHeight;
+    }
+
+    /**
+     * Returns the depth of the MTP object in bits per pixel
+     * Will be zero for non-image objects
+     *
+     * @return the image depth
+     */
+    public final int getImagePixDepth() {
+        return mImagePixDepth;
+    }
+
+    /**
+     * Returns the object handle for the object's parent
+     * Will be zero for the root directory of a storage unit
+     *
+     * @return the object's parent
+     */
+    public final int getParent() {
+        return mParent;
+    }
+
+    /**
+     * Returns the association type for the MTP object
+     * Will be zero objects that are not of format
+     * {@link android.mtp.MtpConstants#FORMAT_ASSOCIATION}
+     * For directories the association type is typically
+     * {@link android.mtp.MtpConstants#ASSOCIATION_TYPE_GENERIC_FOLDER}
+     *
+     * @return the object's association type
+     */
+    public final int getAssociationType() {
+        return mAssociationType;
+    }
+
+    /**
+     * Returns the association description for the MTP object
+     * Will be zero objects that are not of format
+     * {@link android.mtp.MtpConstants#FORMAT_ASSOCIATION}
+     *
+     * @return the object's association description
+     */
+    public final int getAssociationDesc() {
+        return mAssociationDesc;
+    }
+
+   /**
+     * Returns the sequence number for the MTP object
+     * This field is typically not used for MTP devices,
+     * but is sometimes used to define a sequence of photos
+     * on PTP cameras.
+     *
+     * @return the object's sequence number
+     */
+    public final int getSequenceNumber() {
+        return mSequenceNumber;
+    }
+
+   /**
+     * Returns the name of the MTP object
+     *
+     * @return the object's name
+     */
+    public final String getName() {
+        return mName;
+    }
+
+   /**
+     * Returns the creation date of the MTP object
+     * The value is represented as milliseconds since January 1, 1970
+     *
+     * @return the object's creation date
+     */
+    public final long getDateCreated() {
+        return mDateCreated;
+    }
+
+   /**
+     * Returns the modification date of the MTP object
+     * The value is represented as milliseconds since January 1, 1970
+     *
+     * @return the object's modification date
+     */
+    public final long getDateModified() {
+        return mDateModified;
+    }
+
+   /**
+     * Returns a comma separated list of keywords for the MTP object
+     *
+     * @return the object's keyword list
+     */
+    public final String getKeywords() {
+        return mKeywords;
+    }
+}
diff --git a/media/java/android/mtp/MtpStorageInfo.java b/media/java/android/mtp/MtpStorageInfo.java
new file mode 100644
index 0000000..811455a
--- /dev/null
+++ b/media/java/android/mtp/MtpStorageInfo.java
@@ -0,0 +1,82 @@
+/*
+ * 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.
+ */
+
+package android.mtp;
+
+/**
+ * This class encapsulates information about a storage unit on an MTP device.
+ * This corresponds to the StorageInfo Dataset described in
+ * section 5.2.2 of the MTP specification.
+ *
+ * {@hide}
+ */
+public final class MtpStorageInfo {
+
+    private int mStorageId;
+    private long mMaxCapacity;
+    private long mFreeSpace;
+    private String mDescription;
+    private String mVolumeIdentifier;
+
+    // only instantiated via JNI
+    private MtpStorageInfo() {
+    }
+
+    /**
+     * Returns the storage ID for the storage unit
+     *
+     * @return the storage ID
+     */
+    public final int getStorageId() {
+        return mStorageId;
+    }
+
+    /**
+     * Returns the maximum storage capacity for the storage unit in bytes
+     *
+     * @return the maximum capacity
+     */
+    public final long getMaxCapacity() {
+        return mMaxCapacity;
+    }
+
+   /**
+     * Returns the amount of free space in the storage unit in bytes
+     *
+     * @return the amount of free space
+     */
+    public final long getFreeSpace() {
+        return mFreeSpace;
+    }
+
+   /**
+     * Returns the description string for the storage unit
+     *
+     * @return the storage unit description
+     */
+    public final String getDescription() {
+        return mDescription;
+    }
+
+   /**
+     * Returns the volume identifier for the storage unit
+     *
+     * @return the storage volume identifier
+     */
+    public final String getVolumeIdentifier() {
+        return mVolumeIdentifier;
+    }
+}
diff --git a/media/jni/Android.mk b/media/jni/Android.mk
index ab6e512..2a89a2a 100644
--- a/media/jni/Android.mk
+++ b/media/jni/Android.mk
@@ -10,6 +10,7 @@ LOCAL_SRC_FILES:= \
     android_media_MediaProfiles.cpp \
     android_media_AmrInputStream.cpp \
     android_mtp_MtpDatabase.cpp \
+    android_mtp_MtpDevice.cpp \
     android_mtp_MtpServer.cpp \
 
 LOCAL_SHARED_LIBRARIES := \
diff --git a/media/jni/android_media_MediaPlayer.cpp b/media/jni/android_media_MediaPlayer.cpp
index f0609b2..0884e35 100644
--- a/media/jni/android_media_MediaPlayer.cpp
+++ b/media/jni/android_media_MediaPlayer.cpp
@@ -776,6 +776,7 @@ extern int register_android_media_ResampleInputStream(JNIEnv *env);
 extern int register_android_media_MediaProfiles(JNIEnv *env);
 extern int register_android_media_AmrInputStream(JNIEnv *env);
 extern int register_android_mtp_MtpDatabase(JNIEnv *env);
+extern int register_android_mtp_MtpDevice(JNIEnv *env);
 extern int register_android_mtp_MtpServer(JNIEnv *env);
 
 jint JNI_OnLoad(JavaVM* vm, void* reserved)
@@ -829,6 +830,11 @@ jint JNI_OnLoad(JavaVM* vm, void* reserved)
         goto bail;
     }
 
+    if (register_android_mtp_MtpDevice(env) < 0) {
+        LOGE("ERROR: MtpDevice native registration failed");
+        goto bail;
+    }
+
     if (register_android_mtp_MtpServer(env) < 0) {
         LOGE("ERROR: MtpServer native registration failed");
         goto bail;
diff --git a/media/jni/android_mtp_MtpDevice.cpp b/media/jni/android_mtp_MtpDevice.cpp
new file mode 100644
index 0000000..9e67985
--- /dev/null
+++ b/media/jni/android_mtp_MtpDevice.cpp
@@ -0,0 +1,663 @@
+/*
+ * 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_NDEBUG 0
+
+#define LOG_TAG "MtpDeviceJNI"
+#include "utils/Log.h"
+
+#include <stdio.h>
+#include <assert.h>
+#include <limits.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "jni.h"
+#include "JNIHelp.h"
+#include "android_runtime/AndroidRuntime.h"
+#include "private/android_filesystem_config.h"
+
+#include "MtpTypes.h"
+#include "MtpDevice.h"
+#include "MtpDeviceInfo.h"
+#include "MtpStorageInfo.h"
+#include "MtpObjectInfo.h"
+
+using namespace android;
+
+// ----------------------------------------------------------------------------
+
+static jfieldID field_context;
+
+jclass clazz_deviceInfo;
+jclass clazz_storageInfo;
+jclass clazz_objectInfo;
+
+jmethodID constructor_deviceInfo;
+jmethodID constructor_storageInfo;
+jmethodID constructor_objectInfo;
+
+// MtpDeviceInfo fields
+static jfieldID field_deviceInfo_manufacturer;
+static jfieldID field_deviceInfo_model;
+static jfieldID field_deviceInfo_version;
+static jfieldID field_deviceInfo_serialNumber;
+
+// MtpStorageInfo fields
+static jfieldID field_storageInfo_storageId;
+static jfieldID field_storageInfo_maxCapacity;
+static jfieldID field_storageInfo_freeSpace;
+static jfieldID field_storageInfo_description;
+static jfieldID field_storageInfo_volumeIdentifier;
+
+// MtpObjectInfo fields
+static jfieldID field_objectInfo_handle;
+static jfieldID field_objectInfo_storageId;
+static jfieldID field_objectInfo_format;
+static jfieldID field_objectInfo_protectionStatus;
+static jfieldID field_objectInfo_compressedSize;
+static jfieldID field_objectInfo_thumbFormat;
+static jfieldID field_objectInfo_thumbCompressedSize;
+static jfieldID field_objectInfo_thumbPixWidth;
+static jfieldID field_objectInfo_thumbPixHeight;
+static jfieldID field_objectInfo_imagePixWidth;
+static jfieldID field_objectInfo_imagePixHeight;
+static jfieldID field_objectInfo_imagePixDepth;
+static jfieldID field_objectInfo_parent;
+static jfieldID field_objectInfo_associationType;
+static jfieldID field_objectInfo_associationDesc;
+static jfieldID field_objectInfo_sequenceNumber;
+static jfieldID field_objectInfo_name;
+static jfieldID field_objectInfo_dateCreated;
+static jfieldID field_objectInfo_dateModified;
+static jfieldID field_objectInfo_keywords;
+
+#ifdef HAVE_ANDROID_OS
+
+MtpDevice* get_device_from_object(JNIEnv* env, jobject javaDevice)
+{
+    return (MtpDevice*)env->GetIntField(javaDevice, field_context);
+}
+
+static void checkAndClearExceptionFromCallback(JNIEnv* env, const char* methodName) {
+    if (env->ExceptionCheck()) {
+        LOGE("An exception was thrown by callback '%s'.", methodName);
+        LOGE_EX(env);
+        env->ExceptionClear();
+    }
+}
+
+#endif // HAVE_ANDROID_OS
+
+// ----------------------------------------------------------------------------
+
+static jboolean
+android_mtp_MtpDevice_open(JNIEnv *env, jobject thiz, jstring deviceName, jint fd)
+{
+#ifdef HAVE_ANDROID_OS
+    LOGD("open\n");
+    const char *deviceNameStr = env->GetStringUTFChars(deviceName, NULL);
+    MtpDevice* device = MtpDevice::open(deviceNameStr, fd);
+    env->ReleaseStringUTFChars(deviceName, deviceNameStr);
+
+    if (device)
+        env->SetIntField(thiz, field_context, (int)device);
+    return (device != NULL);
+#endif
+}
+
+static void
+android_mtp_MtpDevice_close(JNIEnv *env, jobject thiz)
+{
+#ifdef HAVE_ANDROID_OS
+    LOGD("close\n");
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (device) {
+        device->close();
+        delete device;
+        env->SetIntField(thiz, field_context, 0);
+    }
+#endif
+}
+
+static jobject
+android_mtp_MtpDevice_get_device_info(JNIEnv *env, jobject thiz)
+{
+#ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (!device) {
+        LOGD("android_mtp_MtpDevice_get_device_info device is null");
+        return NULL;
+    }
+    MtpDeviceInfo* deviceInfo = device->getDeviceInfo();
+    if (!deviceInfo) {
+        LOGD("android_mtp_MtpDevice_get_device_info deviceInfo is null");
+        return NULL;
+    }
+    jobject info = env->NewObject(clazz_deviceInfo, constructor_deviceInfo);
+    if (info == NULL) {
+        LOGE("Could not create a MtpDeviceInfo object");
+        delete deviceInfo;
+        return NULL;
+    }
+
+    if (deviceInfo->mManufacturer)
+        env->SetObjectField(info, field_deviceInfo_manufacturer,
+            env->NewStringUTF(deviceInfo->mManufacturer));
+    if (deviceInfo->mModel)
+        env->SetObjectField(info, field_deviceInfo_model,
+            env->NewStringUTF(deviceInfo->mModel));
+    if (deviceInfo->mVersion)
+        env->SetObjectField(info, field_deviceInfo_version,
+            env->NewStringUTF(deviceInfo->mVersion));
+    if (deviceInfo->mSerial)
+        env->SetObjectField(info, field_deviceInfo_serialNumber,
+            env->NewStringUTF(deviceInfo->mSerial));
+
+    delete deviceInfo;
+    return info;
+#else
+    return NULL;
+#endif
+}
+
+static jintArray
+android_mtp_MtpDevice_get_storage_ids(JNIEnv *env, jobject thiz)
+{
+#ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (!device)
+        return NULL;
+    MtpStorageIDList* storageIDs = device->getStorageIDs();
+    if (!storageIDs)
+        return NULL;
+
+    int length = storageIDs->size();
+    jintArray array = env->NewIntArray(length);
+    // FIXME is this cast safe?
+    env->SetIntArrayRegion(array, 0, length, (const jint *)storageIDs->array());
+
+    delete storageIDs;
+    return array;
+#else
+    return NULL;
+#endif
+}
+
+static jobject
+android_mtp_MtpDevice_get_storage_info(JNIEnv *env, jobject thiz, jint storageID)
+{
+#ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (!device)
+        return NULL;
+    MtpStorageInfo* storageInfo = device->getStorageInfo(storageID);
+    if (!storageInfo)
+        return NULL;
+
+    jobject info = env->NewObject(clazz_storageInfo, constructor_storageInfo);
+    if (info == NULL) {
+        LOGE("Could not create a MtpStorageInfo object");
+        delete storageInfo;
+        return NULL;
+    }
+
+    if (storageInfo->mStorageID)
+        env->SetIntField(info, field_storageInfo_storageId, storageInfo->mStorageID);
+    if (storageInfo->mMaxCapacity)
+        env->SetLongField(info, field_storageInfo_maxCapacity, storageInfo->mMaxCapacity);
+    if (storageInfo->mFreeSpaceBytes)
+        env->SetLongField(info, field_storageInfo_freeSpace, storageInfo->mFreeSpaceBytes);
+    if (storageInfo->mStorageDescription)
+        env->SetObjectField(info, field_storageInfo_description,
+            env->NewStringUTF(storageInfo->mStorageDescription));
+    if (storageInfo->mVolumeIdentifier)
+        env->SetObjectField(info, field_storageInfo_volumeIdentifier,
+            env->NewStringUTF(storageInfo->mVolumeIdentifier));
+
+    delete storageInfo;
+    return info;
+#else
+    return NULL;
+#endif
+}
+
+static jintArray
+android_mtp_MtpDevice_get_object_handles(JNIEnv *env, jobject thiz,
+        jint storageID, jint format, jint objectID)
+{
+#ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (!device)
+        return NULL;
+    MtpObjectHandleList* handles = device->getObjectHandles(storageID, format, objectID);
+    if (!handles)
+        return NULL;
+
+    int length = handles->size();
+    jintArray array = env->NewIntArray(length);
+    // FIXME is this cast safe?
+    env->SetIntArrayRegion(array, 0, length, (const jint *)handles->array());
+
+    delete handles;
+    return array;
+#else
+    return NULL;
+#endif
+}
+
+static jobject
+android_mtp_MtpDevice_get_object_info(JNIEnv *env, jobject thiz, jint objectID)
+{
+#ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (!device)
+        return NULL;
+    MtpObjectInfo* objectInfo = device->getObjectInfo(objectID);
+    if (!objectInfo)
+        return NULL;
+    jobject info = env->NewObject(clazz_objectInfo, constructor_objectInfo);
+    if (info == NULL) {
+        LOGE("Could not create a MtpObjectInfo object");
+        delete objectInfo;
+        return NULL;
+    }
+
+    if (objectInfo->mHandle)
+        env->SetIntField(info, field_objectInfo_handle, objectInfo->mHandle);
+    if (objectInfo->mStorageID)
+        env->SetIntField(info, field_objectInfo_storageId, objectInfo->mStorageID);
+    if (objectInfo->mFormat)
+        env->SetIntField(info, field_objectInfo_format, objectInfo->mFormat);
+    if (objectInfo->mProtectionStatus)
+        env->SetIntField(info, field_objectInfo_protectionStatus, objectInfo->mProtectionStatus);
+    if (objectInfo->mCompressedSize)
+        env->SetIntField(info, field_objectInfo_compressedSize, objectInfo->mCompressedSize);
+    if (objectInfo->mThumbFormat)
+        env->SetIntField(info, field_objectInfo_thumbFormat, objectInfo->mThumbFormat);
+    if (objectInfo->mThumbCompressedSize)
+        env->SetIntField(info, field_objectInfo_thumbCompressedSize, objectInfo->mThumbCompressedSize);
+    if (objectInfo->mThumbPixWidth)
+        env->SetIntField(info, field_objectInfo_thumbPixWidth, objectInfo->mThumbPixWidth);
+    if (objectInfo->mThumbPixHeight)
+        env->SetIntField(info, field_objectInfo_thumbPixHeight, objectInfo->mThumbPixHeight);
+    if (objectInfo->mImagePixWidth)
+        env->SetIntField(info, field_objectInfo_imagePixWidth, objectInfo->mImagePixWidth);
+    if (objectInfo->mImagePixHeight)
+        env->SetIntField(info, field_objectInfo_imagePixHeight, objectInfo->mImagePixHeight);
+    if (objectInfo->mImagePixDepth)
+        env->SetIntField(info, field_objectInfo_imagePixDepth, objectInfo->mImagePixDepth);
+    if (objectInfo->mParent)
+        env->SetIntField(info, field_objectInfo_parent, objectInfo->mParent);
+    if (objectInfo->mAssociationType)
+        env->SetIntField(info, field_objectInfo_associationType, objectInfo->mAssociationType);
+    if (objectInfo->mAssociationDesc)
+        env->SetIntField(info, field_objectInfo_associationDesc, objectInfo->mAssociationDesc);
+    if (objectInfo->mSequenceNumber)
+        env->SetIntField(info, field_objectInfo_sequenceNumber, objectInfo->mSequenceNumber);
+    if (objectInfo->mName)
+        env->SetObjectField(info, field_objectInfo_name, env->NewStringUTF(objectInfo->mName));
+    if (objectInfo->mDateCreated)
+        env->SetLongField(info, field_objectInfo_dateCreated, objectInfo->mDateCreated);
+    if (objectInfo->mDateModified)
+        env->SetLongField(info, field_objectInfo_dateModified, objectInfo->mDateModified);
+    if (objectInfo->mKeywords)
+        env->SetObjectField(info, field_objectInfo_keywords,
+            env->NewStringUTF(objectInfo->mKeywords));
+
+    delete objectInfo;
+    return info;
+#else
+    return NULL;
+#endif
+}
+
+struct get_object_callback_data {
+    JNIEnv *env;
+    jbyteArray array;
+};
+
+static bool get_object_callback(void* data, int offset, int length, void* clientData)
+{
+    get_object_callback_data* cbData = (get_object_callback_data *)clientData;
+    cbData->env->SetByteArrayRegion(cbData->array, offset, length, (jbyte *)data);
+    return true;
+}
+
+static jbyteArray
+android_mtp_MtpDevice_get_object(JNIEnv *env, jobject thiz, jint objectID, jint objectSize)
+{
+#ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (!device)
+        return NULL;
+
+    jbyteArray array = env->NewByteArray(objectSize);
+    if (!array) {
+        jniThrowException(env, "java/lang/OutOfMemoryError", NULL);
+        return NULL;
+    }
+
+    get_object_callback_data data;
+    data.env = env;
+    data.array = array;
+
+    if (device->readObject(objectID, get_object_callback, objectSize, &data))
+        return array;
+#endif
+    return NULL;
+}
+
+static jbyteArray
+android_mtp_MtpDevice_get_thumbnail(JNIEnv *env, jobject thiz, jint objectID)
+{
+#ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (!device)
+        return NULL;
+
+    int length;
+    void* thumbnail = device->getThumbnail(objectID, length);
+    if (! thumbnail)
+        return NULL;
+    jbyteArray array = env->NewByteArray(length);
+    env->SetByteArrayRegion(array, 0, length, (const jbyte *)thumbnail);
+
+    free(thumbnail);
+    return array;
+#else
+    return NULL;
+#endif
+}
+
+static jboolean
+android_mtp_MtpDevice_delete_object(JNIEnv *env, jobject thiz, jint object_id)
+{
+#ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (device)
+        return device->deleteObject(object_id);
+    else
+ #endif
+        return NULL;
+}
+
+static jlong
+android_mtp_MtpDevice_get_parent(JNIEnv *env, jobject thiz, jint object_id)
+{
+#ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (device)
+        return device->getParent(object_id);
+    else
+#endif
+        return -1;
+}
+
+static jlong
+android_mtp_MtpDevice_get_storage_id(JNIEnv *env, jobject thiz, jint object_id)
+{
+ #ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (device)
+        return device->getStorageID(object_id);
+    else
+#endif
+        return -1;
+}
+
+static jboolean
+android_mtp_MtpDevice_import_file(JNIEnv *env, jobject thiz, jint object_id, jstring dest_path)
+{
+#ifdef HAVE_ANDROID_OS
+    MtpDevice* device = get_device_from_object(env, thiz);
+    if (device) {
+        const char *destPathStr = env->GetStringUTFChars(dest_path, NULL);
+        bool result = device->readObject(object_id, destPathStr, AID_SDCARD_RW, 0664);
+        env->ReleaseStringUTFChars(dest_path, destPathStr);
+        return result;
+    }
+#endif
+    return NULL;
+}
+
+// ----------------------------------------------------------------------------
+
+static JNINativeMethod gMethods[] = {
+    {"native_open",             "(Ljava/lang/String;I)Z",
+                                        (void *)android_mtp_MtpDevice_open},
+    {"native_close",            "()V",  (void *)android_mtp_MtpDevice_close},
+    {"native_get_device_info",  "()Landroid/mtp/MtpDeviceInfo;",
+                                        (void *)android_mtp_MtpDevice_get_device_info},
+    {"native_get_storage_ids",  "()[I", (void *)android_mtp_MtpDevice_get_storage_ids},
+    {"native_get_storage_info", "(I)Landroid/mtp/MtpStorageInfo;",
+                                        (void *)android_mtp_MtpDevice_get_storage_info},
+    {"native_get_object_handles","(III)[I",
+                                        (void *)android_mtp_MtpDevice_get_object_handles},
+    {"native_get_object_info",  "(I)Landroid/mtp/MtpObjectInfo;",
+                                        (void *)android_mtp_MtpDevice_get_object_info},
+    {"native_get_object",       "(II)[B",(void *)android_mtp_MtpDevice_get_object},
+    {"native_get_thumbnail",    "(I)[B",(void *)android_mtp_MtpDevice_get_thumbnail},
+    {"native_delete_object",    "(I)Z", (void *)android_mtp_MtpDevice_delete_object},
+    {"native_get_parent",       "(I)J", (void *)android_mtp_MtpDevice_get_parent},
+    {"native_get_storage_id",   "(I)J", (void *)android_mtp_MtpDevice_get_storage_id},
+    {"native_import_file",     "(ILjava/lang/String;)Z",
+                                        (void *)android_mtp_MtpDevice_import_file},
+};
+
+static const char* const kClassPathName = "android/mtp/MtpDevice";
+
+int register_android_mtp_MtpDevice(JNIEnv *env)
+{
+    jclass clazz;
+
+    LOGD("register_android_mtp_MtpDevice\n");
+
+    clazz = env->FindClass("android/mtp/MtpDeviceInfo");
+    if (clazz == NULL) {
+        LOGE("Can't find android/mtp/MtpDeviceInfo");
+        return -1;
+    }
+    constructor_deviceInfo = env->GetMethodID(clazz, "<init>", "()V");
+    if (constructor_deviceInfo == NULL) {
+        LOGE("Can't find android/mtp/MtpDeviceInfo constructor");
+        return -1;
+    }
+    field_deviceInfo_manufacturer = env->GetFieldID(clazz, "mManufacturer", "Ljava/lang/String;");
+    if (field_deviceInfo_manufacturer == NULL) {
+        LOGE("Can't find MtpDeviceInfo.mManufacturer");
+        return -1;
+    }
+    field_deviceInfo_model = env->GetFieldID(clazz, "mModel", "Ljava/lang/String;");
+    if (field_deviceInfo_model == NULL) {
+        LOGE("Can't find MtpDeviceInfo.mModel");
+        return -1;
+    }
+    field_deviceInfo_version = env->GetFieldID(clazz, "mVersion", "Ljava/lang/String;");
+    if (field_deviceInfo_version == NULL) {
+        LOGE("Can't find MtpDeviceInfo.mVersion");
+        return -1;
+    }
+    field_deviceInfo_serialNumber = env->GetFieldID(clazz, "mSerialNumber", "Ljava/lang/String;");
+    if (field_deviceInfo_serialNumber == NULL) {
+        LOGE("Can't find MtpDeviceInfo.mSerialNumber");
+        return -1;
+    }
+    clazz_deviceInfo = clazz;
+
+    clazz = env->FindClass("android/mtp/MtpStorageInfo");
+    if (clazz == NULL) {
+        LOGE("Can't find android/mtp/MtpStorageInfo");
+        return -1;
+    }
+    constructor_storageInfo = env->GetMethodID(clazz, "<init>", "()V");
+    if (constructor_storageInfo == NULL) {
+        LOGE("Can't find android/mtp/MtpStorageInfo constructor");
+        return -1;
+    }
+    field_storageInfo_storageId = env->GetFieldID(clazz, "mStorageId", "I");
+    if (field_storageInfo_storageId == NULL) {
+        LOGE("Can't find MtpStorageInfo.mStorageId");
+        return -1;
+    }
+    field_storageInfo_maxCapacity = env->GetFieldID(clazz, "mMaxCapacity", "J");
+    if (field_storageInfo_maxCapacity == NULL) {
+        LOGE("Can't find MtpStorageInfo.mMaxCapacity");
+        return -1;
+    }
+    field_storageInfo_freeSpace = env->GetFieldID(clazz, "mFreeSpace", "J");
+    if (field_storageInfo_freeSpace == NULL) {
+        LOGE("Can't find MtpStorageInfo.mFreeSpace");
+        return -1;
+    }
+    field_storageInfo_description = env->GetFieldID(clazz, "mDescription", "Ljava/lang/String;");
+    if (field_storageInfo_description == NULL) {
+        LOGE("Can't find MtpStorageInfo.mDescription");
+        return -1;
+    }
+    field_storageInfo_volumeIdentifier = env->GetFieldID(clazz, "mVolumeIdentifier", "Ljava/lang/String;");
+    if (field_storageInfo_volumeIdentifier == NULL) {
+        LOGE("Can't find MtpStorageInfo.mVolumeIdentifier");
+        return -1;
+    }
+    clazz_storageInfo = clazz;
+
+    clazz = env->FindClass("android/mtp/MtpObjectInfo");
+    if (clazz == NULL) {
+        LOGE("Can't find android/mtp/MtpObjectInfo");
+        return -1;
+    }
+    constructor_objectInfo = env->GetMethodID(clazz, "<init>", "()V");
+    if (constructor_objectInfo == NULL) {
+        LOGE("Can't find android/mtp/MtpObjectInfo constructor");
+        return -1;
+    }
+    field_objectInfo_handle = env->GetFieldID(clazz, "mHandle", "I");
+    if (field_objectInfo_handle == NULL) {
+        LOGE("Can't find MtpObjectInfo.mHandle");
+        return -1;
+    }
+    field_objectInfo_storageId = env->GetFieldID(clazz, "mStorageId", "I");
+    if (field_objectInfo_storageId == NULL) {
+        LOGE("Can't find MtpObjectInfo.mStorageId");
+        return -1;
+    }
+    field_objectInfo_format = env->GetFieldID(clazz, "mFormat", "I");
+    if (field_objectInfo_format == NULL) {
+        LOGE("Can't find MtpObjectInfo.mFormat");
+        return -1;
+    }
+    field_objectInfo_protectionStatus = env->GetFieldID(clazz, "mProtectionStatus", "I");
+    if (field_objectInfo_protectionStatus == NULL) {
+        LOGE("Can't find MtpObjectInfo.mProtectionStatus");
+        return -1;
+    }
+    field_objectInfo_compressedSize = env->GetFieldID(clazz, "mCompressedSize", "I");
+    if (field_objectInfo_compressedSize == NULL) {
+        LOGE("Can't find MtpObjectInfo.mCompressedSize");
+        return -1;
+    }
+    field_objectInfo_thumbFormat = env->GetFieldID(clazz, "mThumbFormat", "I");
+    if (field_objectInfo_thumbFormat == NULL) {
+        LOGE("Can't find MtpObjectInfo.mThumbFormat");
+        return -1;
+    }
+    field_objectInfo_thumbCompressedSize = env->GetFieldID(clazz, "mThumbCompressedSize", "I");
+    if (field_objectInfo_thumbCompressedSize == NULL) {
+        LOGE("Can't find MtpObjectInfo.mThumbCompressedSize");
+        return -1;
+    }
+    field_objectInfo_thumbPixWidth = env->GetFieldID(clazz, "mThumbPixWidth", "I");
+    if (field_objectInfo_thumbPixWidth == NULL) {
+        LOGE("Can't find MtpObjectInfo.mThumbPixWidth");
+        return -1;
+    }
+    field_objectInfo_thumbPixHeight = env->GetFieldID(clazz, "mThumbPixHeight", "I");
+    if (field_objectInfo_thumbPixHeight == NULL) {
+        LOGE("Can't find MtpObjectInfo.mThumbPixHeight");
+        return -1;
+    }
+    field_objectInfo_imagePixWidth = env->GetFieldID(clazz, "mImagePixWidth", "I");
+    if (field_objectInfo_imagePixWidth == NULL) {
+        LOGE("Can't find MtpObjectInfo.mImagePixWidth");
+        return -1;
+    }
+    field_objectInfo_imagePixHeight = env->GetFieldID(clazz, "mImagePixHeight", "I");
+    if (field_objectInfo_imagePixHeight == NULL) {
+        LOGE("Can't find MtpObjectInfo.mImagePixHeight");
+        return -1;
+    }
+    field_objectInfo_imagePixDepth = env->GetFieldID(clazz, "mImagePixDepth", "I");
+    if (field_objectInfo_imagePixDepth == NULL) {
+        LOGE("Can't find MtpObjectInfo.mImagePixDepth");
+        return -1;
+    }
+    field_objectInfo_parent = env->GetFieldID(clazz, "mParent", "I");
+    if (field_objectInfo_parent == NULL) {
+        LOGE("Can't find MtpObjectInfo.mParent");
+        return -1;
+    }
+    field_objectInfo_associationType = env->GetFieldID(clazz, "mAssociationType", "I");
+    if (field_objectInfo_associationType == NULL) {
+        LOGE("Can't find MtpObjectInfo.mAssociationType");
+        return -1;
+    }
+    field_objectInfo_associationDesc = env->GetFieldID(clazz, "mAssociationDesc", "I");
+    if (field_objectInfo_associationDesc == NULL) {
+        LOGE("Can't find MtpObjectInfo.mAssociationDesc");
+        return -1;
+    }
+    field_objectInfo_sequenceNumber = env->GetFieldID(clazz, "mSequenceNumber", "I");
+    if (field_objectInfo_sequenceNumber == NULL) {
+        LOGE("Can't find MtpObjectInfo.mSequenceNumber");
+        return -1;
+    }
+    field_objectInfo_name = env->GetFieldID(clazz, "mName", "Ljava/lang/String;");
+    if (field_objectInfo_name == NULL) {
+        LOGE("Can't find MtpObjectInfo.mName");
+        return -1;
+    }
+    field_objectInfo_dateCreated = env->GetFieldID(clazz, "mDateCreated", "J");
+    if (field_objectInfo_dateCreated == NULL) {
+        LOGE("Can't find MtpObjectInfo.mDateCreated");
+        return -1;
+    }
+    field_objectInfo_dateModified = env->GetFieldID(clazz, "mDateModified", "J");
+    if (field_objectInfo_dateModified == NULL) {
+        LOGE("Can't find MtpObjectInfo.mDateModified");
+        return -1;
+    }
+    field_objectInfo_keywords = env->GetFieldID(clazz, "mKeywords", "Ljava/lang/String;");
+    if (field_objectInfo_keywords == NULL) {
+        LOGE("Can't find MtpObjectInfo.mKeywords");
+        return -1;
+    }
+    clazz_objectInfo = clazz;
+
+    clazz = env->FindClass("android/mtp/MtpDevice");
+    if (clazz == NULL) {
+        LOGE("Can't find android/mtp/MtpDevice");
+        return -1;
+    }
+    field_context = env->GetFieldID(clazz, "mNativeContext", "I");
+    if (field_context == NULL) {
+        LOGE("Can't find MtpDevice.mNativeContext");
+        return -1;
+    }
+
+    return AndroidRuntime::registerNativeMethods(env,
+                "android/mtp/MtpDevice", gMethods, NELEM(gMethods));
+}
diff --git a/media/mtp/Android.mk b/media/mtp/Android.mk
index 70dc340..c25285e 100644
--- a/media/mtp/Android.mk
+++ b/media/mtp/Android.mk
@@ -21,7 +21,6 @@ ifneq ($(TARGET_SIMULATOR),true)
 include $(CLEAR_VARS)
 
 LOCAL_SRC_FILES:=                                       \
-                  MtpClient.cpp                         \
                   MtpDataPacket.cpp                     \
                   MtpDebug.cpp                          \
                   MtpDevice.cpp                         \
@@ -53,7 +52,6 @@ ifeq ($(HOST_OS),linux)
 include $(CLEAR_VARS)
 
 LOCAL_SRC_FILES:=                                       \
-                  MtpClient.cpp                         \
                   MtpDataPacket.cpp                     \
                   MtpDebug.cpp                          \
                   MtpDevice.cpp                         \
diff --git a/media/mtp/MtpClient.cpp b/media/mtp/MtpClient.cpp
deleted file mode 100644
index c830540..0000000
--- a/media/mtp/MtpClient.cpp
+++ /dev/null
@@ -1,251 +0,0 @@
-/*
- * 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 "MtpClient"
-
-#include "MtpDebug.h"
-#include "MtpClient.h"
-#include "MtpDevice.h"
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/types.h>
-#include <sys/ioctl.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <errno.h>
-
-#include <usbhost/usbhost.h>
-
-struct usb_device;
-
-namespace android {
-
-static bool isMtpDevice(uint16_t vendor, uint16_t product) {
-    // Sandisk Sansa Fuze
-    if (vendor == 0x0781 && product == 0x74c2)
-        return true;
-    // Samsung YP-Z5
-    if (vendor == 0x04e8 && product == 0x503c)
-        return true;
-    return false;
-}
-
-class MtpClientThread : public Thread {
-private:
-    MtpClient*   mClient;
-
-public:
-    MtpClientThread(MtpClient* client)
-        : mClient(client)
-    {
-    }
-
-    virtual bool threadLoop() {
-        return mClient->threadLoop();
-    }
-};
-
-
-MtpClient::MtpClient()
-    :   mThread(NULL),
-        mUsbHostContext(NULL),
-        mDone(false)
-{
-}
-
-MtpClient::~MtpClient() {
-    usb_host_cleanup(mUsbHostContext);
-}
-
-bool MtpClient::start() {
-    Mutex::Autolock autoLock(mMutex);
-
-    if (mThread)
-        return true;
-
-    mUsbHostContext = usb_host_init();
-    if (!mUsbHostContext)
-        return false;
-
-    mThread = new MtpClientThread(this);
-    mThread->run("MtpClientThread");
-    // wait for the thread to do initial device discovery before returning
-    mThreadStartCondition.wait(mMutex);
-
-    return true;
-}
-
-void MtpClient::stop() {
-    mDone = true;
-}
-
-MtpDevice* MtpClient::getDevice(int id) {
-    for (int i = 0; i < mDeviceList.size(); i++) {
-        MtpDevice* device = mDeviceList[i];
-        if (device->getID() == id)
-            return device;
-    }
-    return NULL;
-}
-
-bool MtpClient::usbDeviceAdded(const char *devname) {
-    struct usb_descriptor_header* desc;
-    struct usb_descriptor_iter iter;
-
-    struct usb_device *device = usb_device_open(devname);
-    if (!device) {
-        LOGE("usb_device_open failed\n");
-        return mDone;
-    }
-
-    usb_descriptor_iter_init(device, &iter);
-
-    while ((desc = usb_descriptor_iter_next(&iter)) != NULL) {
-        if (desc->bDescriptorType == USB_DT_INTERFACE) {
-            struct usb_interface_descriptor *interface = (struct usb_interface_descriptor *)desc;
-
-            if (interface->bInterfaceClass == USB_CLASS_STILL_IMAGE &&
-                interface->bInterfaceSubClass == 1 && // Still Image Capture
-                interface->bInterfaceProtocol == 1)     // Picture Transfer Protocol (PIMA 15470)
-            {
-                LOGD("Found camera: \"%s\" \"%s\"\n", usb_device_get_manufacturer_name(device),
-                        usb_device_get_product_name(device));
-            } else if (interface->bInterfaceClass == 0xFF &&
-                    interface->bInterfaceSubClass == 0xFF &&
-                    interface->bInterfaceProtocol == 0) {
-                char* interfaceName = usb_device_get_string(device, interface->iInterface);
-                if (!interfaceName || strcmp(interfaceName, "MTP"))
-                    continue;
-                // Looks like an android style MTP device
-                LOGD("Found MTP device: \"%s\" \"%s\"\n", usb_device_get_manufacturer_name(device),
-                        usb_device_get_product_name(device));
-            } else {
-                // look for special cased devices based on vendor/product ID
-                // we are doing this mainly for testing purposes
-                uint16_t vendor = usb_device_get_vendor_id(device);
-                uint16_t product = usb_device_get_product_id(device);
-                if (!isMtpDevice(vendor, product)) {
-                    // not an MTP or PTP device
-                    continue;
-                }
-                // request MTP OS string and descriptor
-                // some music players need to see this before entering MTP mode.
-                char buffer[256];
-                memset(buffer, 0, sizeof(buffer));
-                int ret = usb_device_send_control(device,
-                        USB_DIR_IN|USB_RECIP_DEVICE|USB_TYPE_STANDARD,
-                        USB_REQ_GET_DESCRIPTOR, (USB_DT_STRING << 8) | 0xEE,
-                        0, sizeof(buffer), buffer);
-                printf("usb_device_send_control returned %d errno: %d\n", ret, errno);
-                if (ret > 0) {
-                    printf("got MTP string %s\n", buffer);
-                    ret = usb_device_send_control(device,
-                            USB_DIR_IN|USB_RECIP_DEVICE|USB_TYPE_VENDOR, 1,
-                            0, 4, sizeof(buffer), buffer);
-                    printf("OS descriptor got %d\n", ret);
-                } else {
-                    printf("no MTP string\n");
-                }
-            }
-
-            // if we got here, then we have a likely MTP or PTP device
-
-            // interface should be followed by three endpoints
-            struct usb_endpoint_descriptor *ep;
-            struct usb_endpoint_descriptor *ep_in_desc = NULL;
-            struct usb_endpoint_descriptor *ep_out_desc = NULL;
-            struct usb_endpoint_descriptor *ep_intr_desc = NULL;
-            for (int i = 0; i < 3; i++) {
-                ep = (struct usb_endpoint_descriptor *)usb_descriptor_iter_next(&iter);
-                if (!ep || ep->bDescriptorType != USB_DT_ENDPOINT) {
-                    LOGE("endpoints not found\n");
-                    return mDone;
-                }
-                if (ep->bmAttributes == USB_ENDPOINT_XFER_BULK) {
-                    if (ep->bEndpointAddress & USB_ENDPOINT_DIR_MASK)
-                        ep_in_desc = ep;
-                    else
-                        ep_out_desc = ep;
-                } else if (ep->bmAttributes == USB_ENDPOINT_XFER_INT &&
-                    ep->bEndpointAddress & USB_ENDPOINT_DIR_MASK) {
-                    ep_intr_desc = ep;
-                }
-            }
-            if (!ep_in_desc || !ep_out_desc || !ep_intr_desc) {
-                LOGE("endpoints not found\n");
-                return mDone;
-            }
-
-            if (usb_device_claim_interface(device, interface->bInterfaceNumber)) {
-                LOGE("usb_device_claim_interface failed errno: %d\n", errno);
-                return mDone;
-            }
-
-            MtpDevice* mtpDevice = new MtpDevice(device, interface->bInterfaceNumber,
-                        ep_in_desc, ep_out_desc, ep_intr_desc);
-            mDeviceList.add(mtpDevice);
-            mtpDevice->initialize();
-            deviceAdded(mtpDevice);
-            return mDone;
-        }
-    }
-
-    usb_device_close(device);
-    return mDone;
-}
-
-bool MtpClient::usbDeviceRemoved(const char *devname) {
-    for (int i = 0; i < mDeviceList.size(); i++) {
-        MtpDevice* device = mDeviceList[i];
-        if (!strcmp(devname, device->getDeviceName())) {
-            deviceRemoved(device);
-            mDeviceList.removeAt(i);
-            delete device;
-            LOGD("Camera removed!\n");
-            break;
-        }
-    }
-    return mDone;
-}
-
-bool MtpClient::usbDiscoveryDone() {
-    Mutex::Autolock autoLock(mMutex);
-    mThreadStartCondition.signal();
-    return mDone;
-}
-
-bool MtpClient::threadLoop() {
-    usb_host_run(mUsbHostContext, usb_device_added, usb_device_removed, usb_discovery_done, this);
-    return false;
-}
-
-int MtpClient::usb_device_added(const char *devname, void* client_data) {
-    LOGD("usb_device_added %s\n", devname);
-    return ((MtpClient *)client_data)->usbDeviceAdded(devname);
-}
-
-int MtpClient::usb_device_removed(const char *devname, void* client_data) {
-    LOGD("usb_device_removed %s\n", devname);
-    return ((MtpClient *)client_data)->usbDeviceRemoved(devname);
-}
-
-int MtpClient::usb_discovery_done(void* client_data) {
-    LOGD("usb_discovery_done\n");
-    return ((MtpClient *)client_data)->usbDiscoveryDone();
-}
-
-}  // namespace android
diff --git a/media/mtp/MtpClient.h b/media/mtp/MtpClient.h
deleted file mode 100644
index fa5c527..0000000
--- a/media/mtp/MtpClient.h
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * 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.
- */
-
-#ifndef _MTP_CLIENT_H
-#define _MTP_CLIENT_H
-
-#include "MtpTypes.h"
-
-#include <utils/threads.h>
-
-struct usb_host_context;
-
-namespace android {
-
-class MtpClientThread;
-
-class MtpClient {
-private:
-    MtpDeviceList               mDeviceList;
-    MtpClientThread*            mThread;
-    Condition                   mThreadStartCondition;
-    Mutex                       mMutex;
-    struct usb_host_context*    mUsbHostContext;
-    bool                        mDone;
-
-public:
-                            MtpClient();
-    virtual                 ~MtpClient();
-
-    bool                    start();
-    void                    stop();
-
-    inline MtpDeviceList&   getDeviceList() { return mDeviceList; }
-    MtpDevice*              getDevice(int id);
-
-
-    virtual void            deviceAdded(MtpDevice *device) = 0;
-    virtual void            deviceRemoved(MtpDevice *device) = 0;
-
-private:
-    // these return true if we should stop monitoring USB and clean up
-    bool                    usbDeviceAdded(const char *devname);
-    bool                    usbDeviceRemoved(const char *devname);
-    bool                    usbDiscoveryDone();
-
-    friend class MtpClientThread;
-    bool                    threadLoop();
-    static int              usb_device_added(const char *devname, void* client_data);
-    static int              usb_device_removed(const char *devname, void* client_data);
-    static int              usb_discovery_done(void* client_data);
-};
-
-}; // namespace android
-
-#endif // _MTP_CLIENT_H
diff --git a/media/mtp/MtpDevice.cpp b/media/mtp/MtpDevice.cpp
index d22c72f..d02ed90 100644
--- a/media/mtp/MtpDevice.cpp
+++ b/media/mtp/MtpDevice.cpp
@@ -38,6 +38,121 @@
 
 namespace android {
 
+static bool isMtpDevice(uint16_t vendor, uint16_t product) {
+    // Sandisk Sansa Fuze
+    if (vendor == 0x0781 && product == 0x74c2)
+        return true;
+    // Samsung YP-Z5
+    if (vendor == 0x04e8 && product == 0x503c)
+        return true;
+    return false;
+}
+
+MtpDevice* MtpDevice::open(const char* deviceName, int fd) {
+    struct usb_device *device = usb_device_new(deviceName, fd);
+    if (!device) {
+        LOGE("usb_device_new failed for %s", deviceName);
+        return NULL;
+    }
+
+    struct usb_descriptor_header* desc;
+    struct usb_descriptor_iter iter;
+
+    usb_descriptor_iter_init(device, &iter);
+
+    while ((desc = usb_descriptor_iter_next(&iter)) != NULL) {
+        if (desc->bDescriptorType == USB_DT_INTERFACE) {
+            struct usb_interface_descriptor *interface = (struct usb_interface_descriptor *)desc;
+
+            if (interface->bInterfaceClass == USB_CLASS_STILL_IMAGE &&
+                interface->bInterfaceSubClass == 1 && // Still Image Capture
+                interface->bInterfaceProtocol == 1)     // Picture Transfer Protocol (PIMA 15470)
+            {
+                LOGD("Found camera: \"%s\" \"%s\"\n", usb_device_get_manufacturer_name(device),
+                        usb_device_get_product_name(device));
+            } else if (interface->bInterfaceClass == 0xFF &&
+                    interface->bInterfaceSubClass == 0xFF &&
+                    interface->bInterfaceProtocol == 0) {
+                char* interfaceName = usb_device_get_string(device, interface->iInterface);
+                if (!interfaceName || strcmp(interfaceName, "MTP"))
+                    continue;
+                // Looks like an android style MTP device
+                LOGD("Found MTP device: \"%s\" \"%s\"\n", usb_device_get_manufacturer_name(device),
+                        usb_device_get_product_name(device));
+            } else {
+                // look for special cased devices based on vendor/product ID
+                // we are doing this mainly for testing purposes
+                uint16_t vendor = usb_device_get_vendor_id(device);
+                uint16_t product = usb_device_get_product_id(device);
+                if (!isMtpDevice(vendor, product)) {
+                    // not an MTP or PTP device
+                    continue;
+                }
+                // request MTP OS string and descriptor
+                // some music players need to see this before entering MTP mode.
+                char buffer[256];
+                memset(buffer, 0, sizeof(buffer));
+                int ret = usb_device_send_control(device,
+                        USB_DIR_IN|USB_RECIP_DEVICE|USB_TYPE_STANDARD,
+                        USB_REQ_GET_DESCRIPTOR, (USB_DT_STRING << 8) | 0xEE,
+                        0, sizeof(buffer), buffer);
+                printf("usb_device_send_control returned %d errno: %d\n", ret, errno);
+                if (ret > 0) {
+                    printf("got MTP string %s\n", buffer);
+                    ret = usb_device_send_control(device,
+                            USB_DIR_IN|USB_RECIP_DEVICE|USB_TYPE_VENDOR, 1,
+                            0, 4, sizeof(buffer), buffer);
+                    printf("OS descriptor got %d\n", ret);
+                } else {
+                    printf("no MTP string\n");
+                }
+            }
+
+            // if we got here, then we have a likely MTP or PTP device
+
+            // interface should be followed by three endpoints
+            struct usb_endpoint_descriptor *ep;
+            struct usb_endpoint_descriptor *ep_in_desc = NULL;
+            struct usb_endpoint_descriptor *ep_out_desc = NULL;
+            struct usb_endpoint_descriptor *ep_intr_desc = NULL;
+            for (int i = 0; i < 3; i++) {
+                ep = (struct usb_endpoint_descriptor *)usb_descriptor_iter_next(&iter);
+                if (!ep || ep->bDescriptorType != USB_DT_ENDPOINT) {
+                    LOGE("endpoints not found\n");
+                    return NULL;
+                }
+                if (ep->bmAttributes == USB_ENDPOINT_XFER_BULK) {
+                    if (ep->bEndpointAddress & USB_ENDPOINT_DIR_MASK)
+                        ep_in_desc = ep;
+                    else
+                        ep_out_desc = ep;
+                } else if (ep->bmAttributes == USB_ENDPOINT_XFER_INT &&
+                    ep->bEndpointAddress & USB_ENDPOINT_DIR_MASK) {
+                    ep_intr_desc = ep;
+                }
+            }
+            if (!ep_in_desc || !ep_out_desc || !ep_intr_desc) {
+                LOGE("endpoints not found\n");
+                return NULL;
+            }
+
+            if (usb_device_claim_interface(device, interface->bInterfaceNumber)) {
+                LOGE("usb_device_claim_interface failed errno: %d\n", errno);
+                return NULL;
+            }
+
+            MtpDevice* mtpDevice = new MtpDevice(device, interface->bInterfaceNumber,
+                        ep_in_desc, ep_out_desc, ep_intr_desc);
+            mtpDevice->initialize();
+            return mtpDevice;
+        }
+    }
+
+    usb_device_close(device);
+    LOGE("device not found");
+    return NULL;
+}
+
 MtpDevice::MtpDevice(struct usb_device* device, int interface,
             const struct usb_endpoint_descriptor *ep_in,
             const struct usb_endpoint_descriptor *ep_out,
@@ -49,7 +164,6 @@ MtpDevice::MtpDevice(struct usb_device* device, int interface,
         mRequestOut(NULL),
         mRequestIntr(NULL),
         mDeviceInfo(NULL),
-        mID(usb_device_get_unique_id(device)),
         mSessionID(0),
         mTransactionID(0),
         mReceivedResponse(false)
@@ -430,6 +544,98 @@ MtpProperty* MtpDevice::getObjectPropDesc(MtpObjectProperty code, MtpObjectForma
     return NULL;
 }
 
+bool MtpDevice::readObject(MtpObjectHandle handle,
+        bool (* callback)(void* data, int offset, int length, void* clientData),
+        int objectSize, void* clientData) {
+    Mutex::Autolock autoLock(mMutex);
+    bool result = false;
+
+    mRequest.reset();
+    mRequest.setParameter(1, handle);
+    if (sendRequest(MTP_OPERATION_GET_OBJECT)
+            && mData.readDataHeader(mRequestIn1)) {
+        uint32_t length = mData.getContainerLength();
+        if (length - MTP_CONTAINER_HEADER_SIZE != objectSize) {
+            LOGE("readObject error objectSize: %d, length: %d",
+                    objectSize, length);
+            goto fail;
+        }
+        length -= MTP_CONTAINER_HEADER_SIZE;
+        uint32_t remaining = length;
+        int offset = 0;
+
+        int initialDataLength = 0;
+        void* initialData = mData.getData(initialDataLength);
+        if (initialData) {
+            if (initialDataLength > 0) {
+                if (!callback(initialData, 0, initialDataLength, clientData))
+                    goto fail;
+                remaining -= initialDataLength;
+                offset += initialDataLength;
+            }
+            free(initialData);
+        }
+
+        // USB reads greater than 16K don't work
+        char buffer1[16384], buffer2[16384];
+        mRequestIn1->buffer = buffer1;
+        mRequestIn2->buffer = buffer2;
+        struct usb_request* req = mRequestIn1;
+        void* writeBuffer = NULL;
+        int writeLength = 0;
+
+        while (remaining > 0 || writeBuffer) {
+            if (remaining > 0) {
+                // queue up a read request
+                req->buffer_length = (remaining > sizeof(buffer1) ? sizeof(buffer1) : remaining);
+                if (mData.readDataAsync(req)) {
+                    LOGE("readDataAsync failed");
+                    goto fail;
+                }
+            } else {
+                req = NULL;
+            }
+
+            if (writeBuffer) {
+                // write previous buffer
+                if (!callback(writeBuffer, offset, writeLength, clientData)) {
+                    LOGE("write failed");
+                    // wait for pending read before failing
+                    if (req)
+                        mData.readDataWait(mDevice);
+                    goto fail;
+                }
+                offset += writeLength;
+                writeBuffer = NULL;
+            }
+
+            // wait for read to complete
+            if (req) {
+                int read = mData.readDataWait(mDevice);
+                if (read < 0)
+                    goto fail;
+
+                if (read > 0) {
+                    writeBuffer = req->buffer;
+                    writeLength = read;
+                    remaining -= read;
+                    req = (req == mRequestIn1 ? mRequestIn2 : mRequestIn1);
+                } else {
+                    writeBuffer = NULL;
+                }
+            }
+        }
+
+        MtpResponseCode response = readResponse();
+        if (response == MTP_RESPONSE_OK)
+            result = true;
+    }
+
+fail:
+    return result;
+}
+
+
 // reads the object's data and writes it to the specified file path
 bool MtpDevice::readObject(MtpObjectHandle handle, const char* destPath, int group, int perm) {
     LOGD("readObject: %s", destPath);
@@ -507,10 +713,14 @@ bool MtpDevice::readObject(MtpObjectHandle handle, const char* destPath, int gro
                 if (read < 0)
                     goto fail;
 
-                writeBuffer = req->buffer;
-                writeLength = read;
-                remaining -= read;
-                req = (req == mRequestIn1 ? mRequestIn2 : mRequestIn1);
+                if (read > 0) {
+                    writeBuffer = req->buffer;
+                    writeLength = read;
+                    remaining -= read;
+                    req = (req == mRequestIn1 ? mRequestIn2 : mRequestIn1);
+                } else {
+                    writeBuffer = NULL;
+                }
             }
         }
 
diff --git a/media/mtp/MtpDevice.h b/media/mtp/MtpDevice.h
index d0a0fb3..b69203e 100644
--- a/media/mtp/MtpDevice.h
+++ b/media/mtp/MtpDevice.h
@@ -45,9 +45,6 @@ private:
     MtpDeviceInfo*          mDeviceInfo;
     MtpPropertyList         mDeviceProperties;
 
-    // a unique ID for the device
-    int                     mID;
-
     // current session ID
     MtpSessionID            mSessionID;
     // current transaction ID
@@ -67,9 +64,10 @@ public:
                                     const struct usb_endpoint_descriptor *ep_in,
                                     const struct usb_endpoint_descriptor *ep_out,
                                     const struct usb_endpoint_descriptor *ep_intr);
-    virtual                 ~MtpDevice();
 
-    inline int              getID() const { return mID; }
+    static MtpDevice*       open(const char* deviceName, int fd);
+
+    virtual                 ~MtpDevice();
 
     void                    initialize();
     void                    close();
@@ -97,7 +95,11 @@ public:
     MtpProperty*            getDevicePropDesc(MtpDeviceProperty code);
     MtpProperty*            getObjectPropDesc(MtpObjectProperty code, MtpObjectFormat format);
 
-    bool                   readObject(MtpObjectHandle handle, const char* destPath, int group,
+    bool                    readObject(MtpObjectHandle handle,
+                                    bool (* callback)(void* data, int offset,
+                                            int length, void* clientData),
+                                    int objectSize, void* clientData);
+    bool                    readObject(MtpObjectHandle handle, const char* destPath, int group,
                                     int perm);
 
 private: