donut snapshot
diff --git a/libs/audioflinger/AudioFlinger.cpp b/libs/audioflinger/AudioFlinger.cpp
index d11e13a..b56221f 100644
--- a/libs/audioflinger/AudioFlinger.cpp
+++ b/libs/audioflinger/AudioFlinger.cpp
@@ -651,27 +651,30 @@
         return BAD_VALUE;
     }
 
-    mHardwareMixerThread->setStreamVolume(stream, value);
-#ifdef WITH_A2DP
-    mA2dpMixerThread->setStreamVolume(stream, value);
-#endif
-
     status_t ret = NO_ERROR;
     if (stream == AudioSystem::VOICE_CALL ||
         stream == AudioSystem::BLUETOOTH_SCO) {
-        
+        float hwValue;
         if (stream == AudioSystem::VOICE_CALL) {
-            value = (float)AudioSystem::logToLinear(value)/100.0f;
+            hwValue = (float)AudioSystem::logToLinear(value)/100.0f;
+            // offset value to reflect actual hardware volume that never reaches 0
+            // 1% corresponds roughly to first step in VOICE_CALL stream volume setting (see AudioService.java)
+            value = 0.01 + 0.99 * value;
         } else { // (type == AudioSystem::BLUETOOTH_SCO)
-            value = 1.0f;
+            hwValue = 1.0f;
         }
 
         AutoMutex lock(mHardwareLock);
         mHardwareStatus = AUDIO_SET_VOICE_VOLUME;
-        ret = mAudioHardware->setVoiceVolume(value);
+        ret = mAudioHardware->setVoiceVolume(hwValue);
         mHardwareStatus = AUDIO_HW_IDLE;
     }
 
+    mHardwareMixerThread->setStreamVolume(stream, value);
+#ifdef WITH_A2DP
+    mA2dpMixerThread->setStreamVolume(stream, value);
+#endif
+
     return ret;
 }
 
@@ -709,7 +712,14 @@
     if (uint32_t(stream) >= AudioSystem::NUM_STREAM_TYPES) {
         return 0.0f;
     }
-    return mHardwareMixerThread->streamVolume(stream);
+    
+    float volume = mHardwareMixerThread->streamVolume(stream); 
+    // remove correction applied by setStreamVolume()
+    if (stream == AudioSystem::VOICE_CALL) {
+        volume = (volume - 0.01) / 0.99 ;
+    }
+    
+    return volume;
 }
 
 bool AudioFlinger::streamMute(int stream) const
@@ -812,17 +822,12 @@
                 if (mForcedRoute == 0 && !(mSavedRoute & AudioSystem::ROUTE_SPEAKER)) {
                     LOGV("Route forced to Speaker ON %08x", mSavedRoute | AudioSystem::ROUTE_SPEAKER);
                     mHardwareMixerThread->setStreamMute(AudioSystem::MUSIC, true);
-                    mHardwareStatus = AUDIO_HW_SET_MASTER_VOLUME;
-                    mAudioHardware->setMasterVolume(0);
                     usleep(mHardwareMixerThread->latency()*1000);
                     mHardwareStatus = AUDIO_HW_SET_ROUTING;
                     mAudioHardware->setRouting(AudioSystem::MODE_NORMAL, mSavedRoute | AudioSystem::ROUTE_SPEAKER);
                     mHardwareStatus = AUDIO_HW_IDLE;
                     // delay track start so that audio hardware has time to siwtch routes
                     usleep(kStartSleepTime);
-                    mHardwareStatus = AUDIO_HW_SET_MASTER_VOLUME;
-                    mAudioHardware->setMasterVolume(mHardwareMixerThread->masterVolume());
-                    mHardwareStatus = AUDIO_HW_IDLE;
                 }
                 mForcedRoute = AudioSystem::ROUTE_SPEAKER;
             }
@@ -1480,18 +1485,6 @@
     return status;
 }
 
-// removeTrack_l() must be called with AudioFlinger::mLock held
-void AudioFlinger::MixerThread::removeTrack_l(wp<Track> track, int name)
-{
-    sp<Track> t = track.promote();
-    if (t!=NULL && (t->mState <= TrackBase::STOPPED)) {
-        t->reset();
-        deleteTrackName_l(name);
-        removeActiveTrack_l(track);
-        mAudioFlinger->mWaitWorkCV.broadcast();
-    }
-}
-
 // destroyTrack_l() must be called with AudioFlinger::mLock held
 void AudioFlinger::MixerThread::destroyTrack_l(const sp<Track>& track)
 {
@@ -1697,7 +1690,7 @@
 
     // Check validity of returned pointer in case the track control block would have been corrupted.
     if (bufferStart < mBuffer || bufferStart > bufferEnd || bufferEnd > mBufferEnd || 
-            cblk->channels == 2 && ((unsigned long)bufferStart & 3) ) {
+        (cblk->channels == 2 && ((unsigned long)bufferStart & 3))) {
         LOGE("TrackBase::getBuffer buffer out of range:\n    start: %p, end %p , mBuffer %p mBufferEnd %p\n    \
                 server %d, serverBase %d, user %d, userBase %d, channels %d",
                 bufferStart, bufferEnd, mBuffer, mBufferEnd,
@@ -1733,7 +1726,6 @@
     wp<Track> weak(this); // never create a strong ref from the dtor
     Mutex::Autolock _l(mMixerThread->mAudioFlinger->mLock);
     mState = TERMINATED;
-    mMixerThread->removeTrack_l(weak, mName);
 }
 
 void AudioFlinger::MixerThread::Track::destroy()
diff --git a/libs/audioflinger/AudioFlinger.h b/libs/audioflinger/AudioFlinger.h
index db5cc74..c7ca9ec 100644
--- a/libs/audioflinger/AudioFlinger.h
+++ b/libs/audioflinger/AudioFlinger.h
@@ -501,7 +501,6 @@
         MixerThread& operator = (const MixerThread&);
   
         status_t    addTrack_l(const sp<Track>& track);
-        void        removeTrack_l(wp<Track> track, int name);
         void        destroyTrack_l(const sp<Track>& track);
         int         getTrackName_l();
         void        deleteTrackName_l(int name);
diff --git a/libs/audioflinger/AudioHardwareInterface.cpp b/libs/audioflinger/AudioHardwareInterface.cpp
index ac76a19..cc1bd8f 100644
--- a/libs/audioflinger/AudioHardwareInterface.cpp
+++ b/libs/audioflinger/AudioHardwareInterface.cpp
@@ -53,7 +53,7 @@
     "EARPIECE ",
     "SPEAKER ",
     "BLUETOOTH ",
-    "HEADSET "
+    "HEADSET ",
     "BLUETOOTH_A2DP "
 };
 static const char* routeNone = "NONE";
diff --git a/libs/surfaceflinger/GPUHardware/GPUHardware.cpp b/libs/surfaceflinger/GPUHardware/GPUHardware.cpp
index eb75f99..7168bf2 100644
--- a/libs/surfaceflinger/GPUHardware/GPUHardware.cpp
+++ b/libs/surfaceflinger/GPUHardware/GPUHardware.cpp
@@ -573,7 +573,11 @@
 
 sp<GPUHardwareInterface> GPUFactory::getGPU()
 {
-    return new GPUHardware();
+    sp<GPUHardwareInterface> gpu;
+    if (access("/dev/hw3d", F_OK) == 0) {
+        gpu = new GPUHardware();
+    }
+    return gpu;
 }
 
 // ---------------------------------------------------------------------------
diff --git a/libs/surfaceflinger/Layer.cpp b/libs/surfaceflinger/Layer.cpp
index f65d669..96395a8 100644
--- a/libs/surfaceflinger/Layer.cpp
+++ b/libs/surfaceflinger/Layer.cpp
@@ -108,7 +108,7 @@
     // we always force a 4-byte aligned bpr.
     uint32_t alignment = 1;
 
-    if (flags & ISurfaceComposer::eGPU) {
+    if ((flags & ISurfaceComposer::eGPU) && (mFlinger->getGPU() != 0)) {
         // FIXME: this value should come from the h/w
         alignment = 8; 
         // FIXME: this is msm7201A specific, as its GPU only supports
diff --git a/libs/surfaceflinger/SurfaceFlinger.cpp b/libs/surfaceflinger/SurfaceFlinger.cpp
index de64f55..167a59b 100644
--- a/libs/surfaceflinger/SurfaceFlinger.cpp
+++ b/libs/surfaceflinger/SurfaceFlinger.cpp
@@ -241,6 +241,9 @@
 status_t SurfaceFlinger::requestGPU(const sp<IGPUCallback>& callback,
         gpu_info_t* gpu)
 {
+    if (mGPU == 0)
+        return INVALID_OPERATION;
+
     IPCThreadState* ipc = IPCThreadState::self();
     const int pid = ipc->getCallingPid();
     status_t err = mGPU->request(pid, callback, gpu);
@@ -249,6 +252,9 @@
 
 status_t SurfaceFlinger::revokeGPU()
 {
+    if (mGPU == 0)
+        return INVALID_OPERATION;
+
     return mGPU->friendlyRevoke();
 }
 
@@ -1600,10 +1606,14 @@
             }
             return NO_ERROR;
             case 1005: // ask GPU revoke
-                mGPU->friendlyRevoke();
+                if (mGPU != 0) {
+                    mGPU->friendlyRevoke();
+                }
                 return NO_ERROR;
             case 1006: // revoke GPU
-                mGPU->unconditionalRevoke();
+                if (mGPU != 0) {
+                    mGPU->unconditionalRevoke();
+                }
                 return NO_ERROR;
             case 1007: // set mFreezeCount
                 mFreezeCount = data.readInt32();
diff --git a/libs/surfaceflinger/VRamHeap.cpp b/libs/surfaceflinger/VRamHeap.cpp
index 0ccd71f..238c602 100644
--- a/libs/surfaceflinger/VRamHeap.cpp
+++ b/libs/surfaceflinger/VRamHeap.cpp
@@ -98,7 +98,7 @@
         }
     }
 
-    if (flags & ISurfaceComposer::eGPU) {
+    if ((flags & ISurfaceComposer::eGPU) && (mFlinger->getGPU() != 0)) {
         // FIXME: this is msm7201A specific, where gpu surfaces may not be secure
         if (!(flags & ISurfaceComposer::eSecure)) {
             // if GPU doesn't work, we try eHardware
diff --git a/libs/ui/Camera.cpp b/libs/ui/Camera.cpp
index b3cbda1..6613700 100644
--- a/libs/ui/Camera.cpp
+++ b/libs/ui/Camera.cpp
@@ -64,15 +64,22 @@
     init();
 }
 
-Camera::Camera(const sp<ICamera>& camera)
+// construct a camera client from an existing camera remote
+sp<Camera> Camera::create(const sp<ICamera>& camera)
 {
-    init();
-    // connect this client to existing camera remote
-    if (camera->connect(this) == NO_ERROR) {
-        mStatus = NO_ERROR;
-        mCamera = camera;
-        camera->asBinder()->linkToDeath(this);
+     LOGV("create");
+     if (camera == 0) {
+         LOGE("camera remote is a NULL pointer");
+         return 0;
+     }
+
+    sp<Camera> c = new Camera();
+    if (camera->connect(c) == NO_ERROR) {
+        c->mStatus = NO_ERROR;
+        c->mCamera = camera;
+        camera->asBinder()->linkToDeath(c);
     }
+    return c;
 }
 
 void Camera::init()
@@ -330,63 +337,65 @@
     mErrorCallbackCookie = cookie;
 }
 
-void Camera::autoFocusCallback(bool focused)
+// callback from camera service
+void Camera::notifyCallback(int32_t msgType, int32_t ext1, int32_t ext2)
 {
-    LOGV("autoFocusCallback");
-    if (mAutoFocusCallback) {
-        mAutoFocusCallback(focused, mAutoFocusCallbackCookie);
+    switch(msgType) {
+    case CAMERA_MSG_ERROR:
+        LOGV("errorCallback");
+        if (mErrorCallback) {
+            mErrorCallback((status_t)ext1, mErrorCallbackCookie);
+        }
+        break;
+    case CAMERA_MSG_FOCUS:
+        LOGV("autoFocusCallback");
+        if (mAutoFocusCallback) {
+            mAutoFocusCallback((bool)ext1, mAutoFocusCallbackCookie);
+        }
+        break;
+    case CAMERA_MSG_SHUTTER:
+        LOGV("shutterCallback");
+        if (mShutterCallback) {
+            mShutterCallback(mShutterCallbackCookie);
+        }
+        break;
+    default:
+        LOGV("notifyCallback(%d, %d, %d)", msgType, ext1, ext2);
+        break;
     }
 }
 
-void Camera::shutterCallback()
+// callback from camera service when frame or image is ready
+void Camera::dataCallback(int32_t msgType, const sp<IMemory>& dataPtr)
 {
-    LOGV("shutterCallback");
-    if (mShutterCallback) {
-        mShutterCallback(mShutterCallbackCookie);
-    }
-}
-
-void Camera::rawCallback(const sp<IMemory>& picture)
-{
-    LOGV("rawCallback");
-    if (mRawCallback) {
-        mRawCallback(picture, mRawCallbackCookie);
-    }
-}
-
-// callback from camera service when image is ready
-void Camera::jpegCallback(const sp<IMemory>& picture)
-{
-    LOGV("jpegCallback");
-    if (mJpegCallback) {
-        mJpegCallback(picture, mJpegCallbackCookie);
-    }
-}
-
-// callback from camera service when preview frame is ready
-void Camera::previewCallback(const sp<IMemory>& frame)
-{
-    LOGV("frameCallback");
-    if (mPreviewCallback) {
-        mPreviewCallback(frame, mPreviewCallbackCookie);
-    }
-}
-
-// callback from camera service when a recording frame is ready
-void Camera::recordingCallback(const sp<IMemory>& frame)
-{
-    LOGV("recordingCallback");
-    if (mRecordingCallback) {
-        mRecordingCallback(frame, mRecordingCallbackCookie);
-    }
-}
-
-// callback from camera service when an error occurs in preview or takePicture
-void Camera::errorCallback(status_t error)
-{
-    LOGV("errorCallback");
-    if (mErrorCallback) {
-        mErrorCallback(error, mErrorCallbackCookie);
+    switch(msgType) {
+    case CAMERA_MSG_PREVIEW_FRAME:
+        LOGV("previewCallback");
+        if (mPreviewCallback) {
+            mPreviewCallback(dataPtr, mPreviewCallbackCookie);
+        }
+        break;
+    case CAMERA_MSG_VIDEO_FRAME:
+        LOGV("recordingCallback");
+        if (mRecordingCallback) {
+            mRecordingCallback(dataPtr, mRecordingCallbackCookie);
+        }
+        break;
+    case CAMERA_MSG_RAW_IMAGE:
+        LOGV("rawCallback");
+        if (mRawCallback) {
+            mRawCallback(dataPtr, mRawCallbackCookie);
+        }
+        break;
+    case CAMERA_MSG_COMPRESSED_IMAGE:
+        LOGV("jpegCallback");
+        if (mJpegCallback) {
+            mJpegCallback(dataPtr, mJpegCallbackCookie);
+        }
+        break;
+    default:
+        LOGV("dataCallback(%d, %p)", msgType, dataPtr.get());
+        break;
     }
 }
 
diff --git a/libs/ui/ICameraClient.cpp b/libs/ui/ICameraClient.cpp
index 4bec9d2..c6cf75c 100644
--- a/libs/ui/ICameraClient.cpp
+++ b/libs/ui/ICameraClient.cpp
@@ -25,13 +25,8 @@
 namespace android {
 
 enum {
-    SHUTTER_CALLBACK = IBinder::FIRST_CALL_TRANSACTION,
-    RAW_CALLBACK,
-    JPEG_CALLBACK,
-    PREVIEW_CALLBACK,
-    ERROR_CALLBACK,
-    AUTOFOCUS_CALLBACK,
-    RECORDING_CALLBACK,
+    NOTIFY_CALLBACK = IBinder::FIRST_CALL_TRANSACTION,
+    DATA_CALLBACK,
 };
 
 class BpCameraClient: public BpInterface<ICameraClient>
@@ -42,74 +37,29 @@
     {
     }
 
-    // callback to let the app know the shutter has closed, ideal for playing the shutter sound
-    void shutterCallback()
+    // generic callback from camera service to app
+    void notifyCallback(int32_t msgType, int32_t ext1, int32_t ext2)
     {
-        LOGV("shutterCallback");
+        LOGV("notifyCallback");
         Parcel data, reply;
         data.writeInterfaceToken(ICameraClient::getInterfaceDescriptor());
-        remote()->transact(SHUTTER_CALLBACK, data, &reply, IBinder::FLAG_ONEWAY);
+        data.writeInt32(msgType);
+        data.writeInt32(ext1);
+        data.writeInt32(ext2);
+        remote()->transact(NOTIFY_CALLBACK, data, &reply, IBinder::FLAG_ONEWAY);
     }
 
-    // callback from camera service to app with picture data
-    void rawCallback(const sp<IMemory>& picture)
+    // generic data callback from camera service to app with image data
+    void dataCallback(int32_t msgType, const sp<IMemory>& imageData)
     {
-        LOGV("rawCallback");
+        LOGV("dataCallback");
         Parcel data, reply;
         data.writeInterfaceToken(ICameraClient::getInterfaceDescriptor());
-        data.writeStrongBinder(picture->asBinder());
-        remote()->transact(RAW_CALLBACK, data, &reply, IBinder::FLAG_ONEWAY);
+        data.writeInt32(msgType);
+        data.writeStrongBinder(imageData->asBinder());
+        remote()->transact(DATA_CALLBACK, data, &reply, IBinder::FLAG_ONEWAY);
     }
 
-    // callback from camera service to app with picture data
-    void jpegCallback(const sp<IMemory>& picture)
-    {
-        LOGV("jpegCallback");
-        Parcel data, reply;
-        data.writeInterfaceToken(ICameraClient::getInterfaceDescriptor());
-        data.writeStrongBinder(picture->asBinder());
-        remote()->transact(JPEG_CALLBACK, data, &reply, IBinder::FLAG_ONEWAY);
-    }
-
-    // callback from camera service to app with preview frame data
-    void previewCallback(const sp<IMemory>& frame)
-    {
-        LOGV("previewCallback");
-        Parcel data, reply;
-        data.writeInterfaceToken(ICameraClient::getInterfaceDescriptor());
-        data.writeStrongBinder(frame->asBinder());
-        remote()->transact(PREVIEW_CALLBACK, data, &reply, IBinder::FLAG_ONEWAY);
-    }
-
-    // callback from camera service to app with recording frame data
-    void recordingCallback(const sp<IMemory>& frame)
-    {
-        LOGV("recordingCallback");
-        Parcel data, reply;
-        data.writeInterfaceToken(ICameraClient::getInterfaceDescriptor());
-        data.writeStrongBinder(frame->asBinder());
-        remote()->transact(RECORDING_CALLBACK, data, &reply, IBinder::FLAG_ONEWAY);
-    }
-
-    // callback from camera service to app to report error
-    void errorCallback(status_t error)
-    {
-        LOGV("errorCallback");
-        Parcel data, reply;
-        data.writeInterfaceToken(ICameraClient::getInterfaceDescriptor());
-        data.writeInt32(error);
-        remote()->transact(ERROR_CALLBACK, data, &reply, IBinder::FLAG_ONEWAY);
-    }
-
-    // callback from camera service to app to report autofocus completion
-    void autoFocusCallback(bool focused)
-    {
-        LOGV("autoFocusCallback");
-        Parcel data, reply;
-        data.writeInterfaceToken(ICameraClient::getInterfaceDescriptor());
-        data.writeInt32(focused);
-        remote()->transact(AUTOFOCUS_CALLBACK, data, &reply, IBinder::FLAG_ONEWAY);
-    }
 };
 
 IMPLEMENT_META_INTERFACE(CameraClient, "android.hardware.ICameraClient");
@@ -126,52 +76,21 @@
     uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags)
 {
     switch(code) {
-        case SHUTTER_CALLBACK: {
-            LOGV("SHUTTER_CALLBACK");
+        case NOTIFY_CALLBACK: {
+            LOGV("NOTIFY_CALLBACK");
             CHECK_INTERFACE(ICameraClient, data, reply);
-            shutterCallback();
+            int32_t msgType = data.readInt32();
+            int32_t ext1 = data.readInt32();
+            int32_t ext2 = data.readInt32();
+            notifyCallback(msgType, ext1, ext2);
             return NO_ERROR;
         } break;
-        case RAW_CALLBACK: {
+        case DATA_CALLBACK: {
             LOGV("RAW_CALLBACK");
             CHECK_INTERFACE(ICameraClient, data, reply);
-            sp<IMemory> picture = interface_cast<IMemory>(data.readStrongBinder());
-            rawCallback(picture);
-            return NO_ERROR;
-        } break;
-        case JPEG_CALLBACK: {
-            LOGV("JPEG_CALLBACK");
-            CHECK_INTERFACE(ICameraClient, data, reply);
-            sp<IMemory> picture = interface_cast<IMemory>(data.readStrongBinder());
-            jpegCallback(picture);
-            return NO_ERROR;
-        } break;
-        case PREVIEW_CALLBACK: {
-            LOGV("PREVIEW_CALLBACK");
-            CHECK_INTERFACE(ICameraClient, data, reply);
-            sp<IMemory> frame = interface_cast<IMemory>(data.readStrongBinder());
-            previewCallback(frame);
-            return NO_ERROR;
-        } break;
-        case RECORDING_CALLBACK: {
-            LOGV("RECORDING_CALLBACK");
-            CHECK_INTERFACE(ICameraClient, data, reply);
-            sp<IMemory> frame = interface_cast<IMemory>(data.readStrongBinder());
-            recordingCallback(frame);
-            return NO_ERROR;
-        } break;
-        case ERROR_CALLBACK: {
-            LOGV("ERROR_CALLBACK");
-            CHECK_INTERFACE(ICameraClient, data, reply);
-            status_t error = data.readInt32();
-            errorCallback(error);
-            return NO_ERROR;
-        } break;
-        case AUTOFOCUS_CALLBACK: {
-            LOGV("AUTOFOCUS_CALLBACK");
-            CHECK_INTERFACE(ICameraClient, data, reply);
-            bool focused = (bool)data.readInt32();
-            autoFocusCallback(focused);
+            int32_t msgType = data.readInt32();
+            sp<IMemory> imageData = interface_cast<IMemory>(data.readStrongBinder());
+            dataCallback(msgType, imageData);
             return NO_ERROR;
         } break;
         default:
diff --git a/libs/utils/Android.mk b/libs/utils/Android.mk
index cdb8ca2..f9fb780 100644
--- a/libs/utils/Android.mk
+++ b/libs/utils/Android.mk
@@ -116,7 +116,8 @@
 	ProcessState.cpp \
 	IPermissionController.cpp \
 	IServiceManager.cpp \
-	Unicode.cpp
+	Unicode.cpp \
+	file_backup_helper.cpp
 
 ifeq ($(TARGET_SIMULATOR),true)
 LOCAL_SRC_FILES += $(hostSources)
diff --git a/libs/utils/ResourceTypes.cpp b/libs/utils/ResourceTypes.cpp
index 2ad3bfe..3d12dca 100644
--- a/libs/utils/ResourceTypes.cpp
+++ b/libs/utils/ResourceTypes.cpp
@@ -1820,7 +1820,7 @@
             }
         }
         
-        if (bestPackage != NULL && bestItem.isBetterThan(thisConfig)) {
+        if (bestPackage != NULL && bestItem.isMoreSpecificThan(thisConfig)) {
             continue;
         }
         
diff --git a/libs/utils/file_backup_helper.cpp b/libs/utils/file_backup_helper.cpp
new file mode 100644
index 0000000..453084a
--- /dev/null
+++ b/libs/utils/file_backup_helper.cpp
@@ -0,0 +1,685 @@
+#define LOG_TAG "file_backup_helper"
+
+#include <utils/backup_helpers.h>
+
+#include <utils/KeyedVector.h>
+#include <utils/ByteOrder.h>
+#include <utils/String8.h>
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <sys/stat.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <utime.h>
+#include <fcntl.h>
+#include <zlib.h>
+
+#include <cutils/log.h>
+
+using namespace android;
+
+#define MAGIC0 0x70616e53 // Snap
+#define MAGIC1 0x656c6946 // File
+
+#define LOGP(x...) LOGD(x)
+//#define LOGP(x...) printf(x)
+
+struct SnapshotHeader {
+    int magic0;
+    int fileCount;
+    int magic1;
+    int totalSize;
+};
+
+struct FileState {
+    int modTime_sec;
+    int modTime_nsec;
+    int size;
+    int crc32;
+    int nameLen;
+};
+
+const static int ROUND_UP[4] = { 0, 3, 2, 1 };
+
+static inline int
+round_up(int n)
+{
+    return n + ROUND_UP[n % 4];
+}
+
+static int
+read_snapshot_file(int fd, KeyedVector<String8,FileState>* snapshot)
+{
+    int bytesRead = 0;
+    int amt;
+    SnapshotHeader header;
+
+    amt = read(fd, &header, sizeof(header));
+    if (amt != sizeof(header)) {
+        return errno;
+    }
+    bytesRead += amt;
+
+    if (header.magic0 != MAGIC0 || header.magic1 != MAGIC1) {
+        LOGW("read_snapshot_file header.magic0=0x%08x magic1=0x%08x", header.magic0, header.magic1);
+        return 1;
+    }
+
+    for (int i=0; i<header.fileCount; i++) {
+        FileState file;
+        char filenameBuf[128];
+
+        amt = read(fd, &file, sizeof(file));
+        if (amt != sizeof(file)) {
+            LOGW("read_snapshot_file FileState truncated/error with read at %d bytes\n", bytesRead);
+            return 1;
+        }
+        bytesRead += amt;
+
+        // filename is not NULL terminated, but it is padded
+        int nameBufSize = round_up(file.nameLen);
+        char* filename = nameBufSize <= (int)sizeof(filenameBuf)
+                ? filenameBuf
+                : (char*)malloc(nameBufSize);
+        amt = read(fd, filename, nameBufSize);
+        if (amt == nameBufSize) {
+            snapshot->add(String8(filename, file.nameLen), file);
+        }
+        bytesRead += amt;
+        if (filename != filenameBuf) {
+            free(filename);
+        }
+        if (amt != nameBufSize) {
+            LOGW("read_snapshot_file filename truncated/error with read at %d bytes\n", bytesRead);
+            return 1;
+        }
+    }
+
+    if (header.totalSize != bytesRead) {
+        LOGW("read_snapshot_file length mismatch: header.totalSize=%d bytesRead=%d\n",
+                header.totalSize, bytesRead);
+        return 1;
+    }
+
+    return 0;
+}
+
+static int
+write_snapshot_file(int fd, const KeyedVector<String8,FileState>& snapshot)
+{
+    int bytesWritten = sizeof(SnapshotHeader);
+    // preflight size
+    const int N = snapshot.size();
+    for (int i=0; i<N; i++) {
+        const String8& name = snapshot.keyAt(i);
+        bytesWritten += sizeof(FileState) + round_up(name.length());
+    }
+
+    int amt;
+    SnapshotHeader header = { MAGIC0, N, MAGIC1, bytesWritten };
+
+    amt = write(fd, &header, sizeof(header));
+    if (amt != sizeof(header)) {
+        LOGW("write_snapshot_file error writing header %s", strerror(errno));
+        return errno;
+    }
+
+    for (int i=0; i<header.fileCount; i++) {
+        const String8& name = snapshot.keyAt(i);
+        FileState file = snapshot.valueAt(i);
+        int nameLen = file.nameLen = name.length();
+
+        amt = write(fd, &file, sizeof(file));
+        if (amt != sizeof(file)) {
+            LOGW("write_snapshot_file error writing header %s", strerror(errno));
+            return 1;
+        }
+
+        // filename is not NULL terminated, but it is padded
+        amt = write(fd, name.string(), nameLen);
+        if (amt != nameLen) {
+            LOGW("write_snapshot_file error writing filename %s", strerror(errno));
+            return 1;
+        }
+        int paddingLen = ROUND_UP[nameLen % 4];
+        if (paddingLen != 0) {
+            int padding = 0xabababab;
+            amt = write(fd, &padding, paddingLen);
+            if (amt != paddingLen) {
+                LOGW("write_snapshot_file error writing %d bytes of filename padding %s",
+                        paddingLen, strerror(errno));
+                return 1;
+            }
+        }
+    }
+
+    return 0;
+}
+
+static int
+write_delete_file(const String8& key)
+{
+    LOGP("write_delete_file %s\n", key.string());
+    return 0;
+}
+
+static int
+write_update_file(const String8& realFilename, const String8& key)
+{
+    LOGP("write_update_file %s (%s)\n", realFilename.string(), key.string());
+    return 0;
+}
+
+static int
+compute_crc32(const String8& filename)
+{
+    const int bufsize = 4*1024;
+    int amt;
+
+    int fd = open(filename.string(), O_RDONLY);
+    if (fd == -1) {
+        return -1;
+    }
+
+    char* buf = (char*)malloc(bufsize);
+    int crc = crc32(0L, Z_NULL, 0);
+
+    while ((amt = read(fd, buf, bufsize)) != 0) {
+        crc = crc32(crc, (Bytef*)buf, amt);
+    }
+
+    close(fd);
+    free(buf);
+
+    return crc;
+}
+
+int
+back_up_files(int oldSnapshotFD, int oldDataStream, int newSnapshotFD,
+        char const* fileBase, char const* const* files, int fileCount)
+{
+    int err;
+    const String8 base(fileBase);
+    KeyedVector<String8,FileState> oldSnapshot;
+    KeyedVector<String8,FileState> newSnapshot;
+
+    if (oldSnapshotFD != -1) {
+        err = read_snapshot_file(oldSnapshotFD, &oldSnapshot);
+        if (err != 0) {
+            // On an error, treat this as a full backup.
+            oldSnapshot.clear();
+        }
+    }
+
+    for (int i=0; i<fileCount; i++) {
+        String8 name(files[i]);
+        FileState s;
+        struct stat st;
+        String8 realFilename(base);
+        realFilename.appendPath(name);
+
+        err = stat(realFilename.string(), &st);
+        if (err != 0) {
+            LOGW("Error stating file %s", realFilename.string());
+            continue;
+        }
+
+        s.modTime_sec = st.st_mtime;
+        s.modTime_nsec = 0; // workaround sim breakage
+        //s.modTime_nsec = st.st_mtime_nsec;
+        s.size = st.st_size;
+        s.crc32 = compute_crc32(realFilename);
+
+        newSnapshot.add(name, s);
+    }
+
+    int n = 0;
+    int N = oldSnapshot.size();
+    int m = 0;
+
+    while (n<N && m<fileCount) {
+        const String8& p = oldSnapshot.keyAt(n);
+        const String8& q = newSnapshot.keyAt(m);
+        int cmp = p.compare(q);
+        if (cmp > 0) {
+            // file added
+            String8 realFilename(base);
+            realFilename.appendPath(q);
+            write_update_file(realFilename, q);
+            m++;
+        }
+        else if (cmp < 0) {
+            // file removed
+            write_delete_file(p);
+            n++;
+        }
+        else {
+            // both files exist, check them
+            String8 realFilename(base);
+            realFilename.appendPath(q);
+            const FileState& f = oldSnapshot.valueAt(n);
+            const FileState& g = newSnapshot.valueAt(m);
+
+            LOGP("%s\n", q.string());
+            LOGP("  new: modTime=%d,%d size=%-3d crc32=0x%08x\n",
+                    f.modTime_sec, f.modTime_nsec, f.size, f.crc32);
+            LOGP("  old: modTime=%d,%d size=%-3d crc32=0x%08x\n",
+                    g.modTime_sec, g.modTime_nsec, g.size, g.crc32);
+            if (f.modTime_sec != g.modTime_sec || f.modTime_nsec != g.modTime_nsec
+                    || f.size != g.size || f.crc32 != g.crc32) {
+                write_update_file(realFilename, p);
+            }
+            n++;
+            m++;
+        }
+    }
+
+    // these were deleted
+    while (n<N) {
+        write_delete_file(oldSnapshot.keyAt(n));
+        n++;
+    }
+
+    // these were added
+    while (m<fileCount) {
+        const String8& q = newSnapshot.keyAt(m);
+        String8 realFilename(base);
+        realFilename.appendPath(q);
+        write_update_file(realFilename, q);
+        m++;
+    }
+
+    err = write_snapshot_file(newSnapshotFD, newSnapshot);
+
+    return 0;
+}
+
+#if TEST_BACKUP_HELPERS
+
+#define SCRATCH_DIR "/data/backup_helper_test/"
+
+static int
+write_text_file(const char* path, const char* data)
+{
+    int amt;
+    int fd;
+    int len;
+
+    fd = creat(path, 0666);
+    if (fd == -1) {
+        fprintf(stderr, "creat %s failed\n", path);
+        return errno;
+    }
+
+    len = strlen(data);
+    amt = write(fd, data, len);
+    if (amt != len) {
+        fprintf(stderr, "error (%s) writing to file %s\n", strerror(errno), path);
+        return errno;
+    }
+
+    close(fd);
+
+    return 0;
+}
+
+static int
+compare_file(const char* path, const unsigned char* data, int len)
+{
+    int fd;
+    int amt;
+
+    fd = open(path, O_RDONLY);
+    if (fd == -1) {
+        fprintf(stderr, "compare_file error (%s) opening %s\n", strerror(errno), path);
+        return errno;
+    }
+
+    unsigned char* contents = (unsigned char*)malloc(len);
+    if (contents == NULL) {
+        fprintf(stderr, "malloc(%d) failed\n", len);
+        return ENOMEM;
+    }
+
+    bool sizesMatch = true;
+    amt = lseek(fd, 0, SEEK_END);
+    if (amt != len) {
+        fprintf(stderr, "compare_file file length should be %d, was %d\n", len, amt);
+        sizesMatch = false;
+    }
+    lseek(fd, 0, SEEK_SET);
+
+    int readLen = amt < len ? amt : len;
+    amt = read(fd, contents, readLen);
+    if (amt != readLen) {
+        fprintf(stderr, "compare_file read expected %d bytes but got %d\n", len, amt);
+    }
+
+    bool contentsMatch = true;
+    for (int i=0; i<readLen; i++) {
+        if (data[i] != contents[i]) {
+            if (contentsMatch) {
+                fprintf(stderr, "compare_file contents are different: (index, expected, actual)\n");
+                contentsMatch = false;
+            }
+            fprintf(stderr, "  [%-2d] %02x %02x\n", i, data[i], contents[i]);
+        }
+    }
+
+    return contentsMatch && sizesMatch ? 0 : 1;
+}
+
+int
+backup_helper_test_empty()
+{
+    int err;
+    int fd;
+    KeyedVector<String8,FileState> snapshot;
+    const char* filename = SCRATCH_DIR "backup_helper_test_empty.snap";
+
+    system("rm -r " SCRATCH_DIR);
+    mkdir(SCRATCH_DIR, 0777);
+
+    // write
+    fd = creat(filename, 0666);
+    if (fd == -1) {
+        fprintf(stderr, "error creating %s\n", filename);
+        return 1;
+    }
+
+    err = write_snapshot_file(fd, snapshot);
+
+    close(fd);
+
+    if (err != 0) {
+        fprintf(stderr, "write_snapshot_file reported error %d (%s)\n", err, strerror(err));
+        return err;
+    }
+
+    static const unsigned char correct_data[] = {
+        0x53, 0x6e, 0x61, 0x70,  0x00, 0x00, 0x00, 0x00,
+        0x46, 0x69, 0x6c, 0x65,  0x10, 0x00, 0x00, 0x00
+    };
+
+    err = compare_file(filename, correct_data, sizeof(correct_data));
+    if (err != 0) {
+        return err;
+    }
+
+    // read
+    fd = open(filename, O_RDONLY);
+    if (fd == -1) {
+        fprintf(stderr, "error opening for read %s\n", filename);
+        return 1;
+    }
+
+    KeyedVector<String8,FileState> readSnapshot;
+    err = read_snapshot_file(fd, &readSnapshot);
+    if (err != 0) {
+        fprintf(stderr, "read_snapshot_file failed %d\n", err);
+        return err;
+    }
+
+    if (readSnapshot.size() != 0) {
+        fprintf(stderr, "readSnapshot should be length 0\n");
+        return 1;
+    }
+
+    return 0;
+}
+
+int
+backup_helper_test_four()
+{
+    int err;
+    int fd;
+    KeyedVector<String8,FileState> snapshot;
+    const char* filename = SCRATCH_DIR "backup_helper_test_four.snap";
+
+    system("rm -r " SCRATCH_DIR);
+    mkdir(SCRATCH_DIR, 0777);
+
+    // write
+    fd = creat(filename, 0666);
+    if (fd == -1) {
+        fprintf(stderr, "error opening %s\n", filename);
+        return 1;
+    }
+
+    String8 filenames[4];
+    FileState states[4];
+
+    states[0].modTime_sec = 0xfedcba98;
+    states[0].modTime_nsec = 0xdeadbeef;
+    states[0].size = 0xababbcbc;
+    states[0].crc32 = 0x12345678;
+    states[0].nameLen = -12;
+    filenames[0] = String8("bytes_of_padding");
+    snapshot.add(filenames[0], states[0]);
+
+    states[1].modTime_sec = 0x93400031;
+    states[1].modTime_nsec = 0xdeadbeef;
+    states[1].size = 0x88557766;
+    states[1].crc32 = 0x22334422;
+    states[1].nameLen = -1;
+    filenames[1] = String8("bytes_of_padding3");
+    snapshot.add(filenames[1], states[1]);
+
+    states[2].modTime_sec = 0x33221144;
+    states[2].modTime_nsec = 0xdeadbeef;
+    states[2].size = 0x11223344;
+    states[2].crc32 = 0x01122334;
+    states[2].nameLen = 0;
+    filenames[2] = String8("bytes_of_padding_2");
+    snapshot.add(filenames[2], states[2]);
+
+    states[3].modTime_sec = 0x33221144;
+    states[3].modTime_nsec = 0xdeadbeef;
+    states[3].size = 0x11223344;
+    states[3].crc32 = 0x01122334;
+    states[3].nameLen = 0;
+    filenames[3] = String8("bytes_of_padding__1");
+    snapshot.add(filenames[3], states[3]);
+
+    err = write_snapshot_file(fd, snapshot);
+
+    close(fd);
+
+    if (err != 0) {
+        fprintf(stderr, "write_snapshot_file reported error %d (%s)\n", err, strerror(err));
+        return err;
+    }
+
+    static const unsigned char correct_data[] = {
+        // header
+        0x53, 0x6e, 0x61, 0x70,  0x04, 0x00, 0x00, 0x00,
+        0x46, 0x69, 0x6c, 0x65,  0xac, 0x00, 0x00, 0x00,
+
+        // bytes_of_padding
+        0x98, 0xba, 0xdc, 0xfe,  0xef, 0xbe, 0xad, 0xde,
+        0xbc, 0xbc, 0xab, 0xab,  0x78, 0x56, 0x34, 0x12,
+        0x10, 0x00, 0x00, 0x00,  0x62, 0x79, 0x74, 0x65,
+        0x73, 0x5f, 0x6f, 0x66,  0x5f, 0x70, 0x61, 0x64,
+        0x64, 0x69, 0x6e, 0x67,
+
+        // bytes_of_padding3
+        0x31, 0x00, 0x40, 0x93,  0xef, 0xbe, 0xad, 0xde,
+        0x66, 0x77, 0x55, 0x88,  0x22, 0x44, 0x33, 0x22,
+        0x11, 0x00, 0x00, 0x00,  0x62, 0x79, 0x74, 0x65,
+        0x73, 0x5f, 0x6f, 0x66,  0x5f, 0x70, 0x61, 0x64,
+        0x64, 0x69, 0x6e, 0x67,  0x33, 0xab, 0xab, 0xab,
+        
+        // bytes of padding2
+        0x44, 0x11, 0x22, 0x33,  0xef, 0xbe, 0xad, 0xde,
+        0x44, 0x33, 0x22, 0x11,  0x34, 0x23, 0x12, 0x01,
+        0x12, 0x00, 0x00, 0x00,  0x62, 0x79, 0x74, 0x65,
+        0x73, 0x5f, 0x6f, 0x66,  0x5f, 0x70, 0x61, 0x64,
+        0x64, 0x69, 0x6e, 0x67,  0x5f, 0x32, 0xab, 0xab,
+        
+        // bytes of padding3
+        0x44, 0x11, 0x22, 0x33,  0xef, 0xbe, 0xad, 0xde,
+        0x44, 0x33, 0x22, 0x11,  0x34, 0x23, 0x12, 0x01,
+        0x13, 0x00, 0x00, 0x00,  0x62, 0x79, 0x74, 0x65,
+        0x73, 0x5f, 0x6f, 0x66,  0x5f, 0x70, 0x61, 0x64,
+        0x64, 0x69, 0x6e, 0x67,  0x5f, 0x5f, 0x31, 0xab
+    };
+
+    err = compare_file(filename, correct_data, sizeof(correct_data));
+    if (err != 0) {
+        return err;
+    }
+    
+    // read
+    fd = open(filename, O_RDONLY);
+    if (fd == -1) {
+        fprintf(stderr, "error opening for read %s\n", filename);
+        return 1;
+    }
+
+
+    KeyedVector<String8,FileState> readSnapshot;
+    err = read_snapshot_file(fd, &readSnapshot);
+    if (err != 0) {
+        fprintf(stderr, "read_snapshot_file failed %d\n", err);
+        return err;
+    }
+
+    if (readSnapshot.size() != 4) {
+        fprintf(stderr, "readSnapshot should be length 4 is %d\n", readSnapshot.size());
+        return 1;
+    }
+
+    bool matched = true;
+    for (size_t i=0; i<readSnapshot.size(); i++) {
+        const String8& name = readSnapshot.keyAt(i);
+        const FileState state = readSnapshot.valueAt(i);
+
+        if (name != filenames[i] || states[i].modTime_sec != state.modTime_sec
+                || states[i].modTime_nsec != state.modTime_nsec
+                || states[i].size != state.size || states[i].crc32 != states[i].crc32) {
+            fprintf(stderr, "state %d expected={%d/%d, 0x%08x, 0x%08x, %3d} '%s'\n"
+                            "          actual={%d/%d, 0x%08x, 0x%08x, %3d} '%s'\n", i,
+                    states[i].modTime_sec, states[i].modTime_nsec, states[i].size, states[i].crc32,
+                    name.length(), filenames[i].string(),
+                    state.modTime_sec, state.modTime_nsec, state.size, state.crc32, state.nameLen,
+                    name.string());
+            matched = false;
+        }
+    }
+    
+    return matched ? 0 : 1;
+}
+
+static int
+get_mod_time(const char* filename, struct timeval times[2])
+{
+    int err;
+    struct stat64 st;
+    err = stat64(filename, &st);
+    if (err != 0) {
+        fprintf(stderr, "stat '%s' failed: %s\n", filename, strerror(errno));
+        return errno;
+    }
+    times[0].tv_sec = st.st_atime;
+    times[0].tv_usec = st.st_atime_nsec / 1000;
+    times[1].tv_sec = st.st_mtime;
+    times[1].tv_usec = st.st_mtime_nsec / 1000;
+    return 0;
+}
+
+int
+backup_helper_test_files()
+{
+    int err;
+    int newSnapshotFD;
+    int oldSnapshotFD;
+
+    system("rm -r " SCRATCH_DIR);
+    mkdir(SCRATCH_DIR, 0777);
+    mkdir(SCRATCH_DIR "data", 0777);
+
+    write_text_file(SCRATCH_DIR "data/b", "b\nbb\n");
+    write_text_file(SCRATCH_DIR "data/c", "c\ncc\n");
+    write_text_file(SCRATCH_DIR "data/d", "d\ndd\n");
+    write_text_file(SCRATCH_DIR "data/e", "e\nee\n");
+    write_text_file(SCRATCH_DIR "data/f", "f\nff\n");
+    write_text_file(SCRATCH_DIR "data/h", "h\nhh\n");
+
+    char const* files_before[] = {
+        "data/b",
+        "data/c",
+        "data/d",
+        "data/e",
+        "data/f"
+    };
+
+    newSnapshotFD = creat(SCRATCH_DIR "before.snap", 0666);
+    if (newSnapshotFD == -1) {
+        fprintf(stderr, "error creating: %s\n", strerror(errno));
+        return errno;
+    }
+
+    err = back_up_files(-1, newSnapshotFD, 0, SCRATCH_DIR, files_before, 5);
+    if (err != 0) {
+        return err;
+    }
+
+    close(newSnapshotFD);
+
+    sleep(3);
+
+    struct timeval d_times[2];
+    struct timeval e_times[2];
+
+    err = get_mod_time(SCRATCH_DIR "data/d", d_times);
+    err |= get_mod_time(SCRATCH_DIR "data/e", e_times);
+    if (err != 0) {
+        return err;
+    }
+
+    write_text_file(SCRATCH_DIR "data/a", "a\naa\n");
+    unlink(SCRATCH_DIR "data/c");
+    write_text_file(SCRATCH_DIR "data/c", "c\ncc\n");
+    write_text_file(SCRATCH_DIR "data/d", "dd\ndd\n");
+    utimes(SCRATCH_DIR "data/d", d_times);
+    write_text_file(SCRATCH_DIR "data/e", "z\nzz\n");
+    utimes(SCRATCH_DIR "data/e", e_times);
+    write_text_file(SCRATCH_DIR "data/g", "g\ngg\n");
+    unlink(SCRATCH_DIR "data/f");
+    
+    char const* files_after[] = {
+        "data/a", // added
+        "data/b", // same
+        "data/c", // different mod time
+        "data/d", // different size (same mod time)
+        "data/e", // different contents (same mod time, same size)
+        "data/g"  // added
+    };
+
+    oldSnapshotFD = open(SCRATCH_DIR "before.snap", O_RDONLY);
+    if (oldSnapshotFD == -1) {
+        fprintf(stderr, "error opening: %s\n", strerror(errno));
+        return errno;
+    }
+
+    newSnapshotFD = creat(SCRATCH_DIR "after.snap", 0666);
+    if (newSnapshotFD == -1) {
+        fprintf(stderr, "error creating: %s\n", strerror(errno));
+        return errno;
+    }
+
+    err = back_up_files(oldSnapshotFD, newSnapshotFD, 0, SCRATCH_DIR, files_after, 6);
+    if (err != 0) {
+        return err;
+    }
+
+    close(oldSnapshotFD);
+    close(newSnapshotFD);
+    
+    return 0;
+}
+
+#endif // TEST_BACKUP_HELPERS