Add new `hid` command.

This allows the shell user to inject HID events.

Change-Id: I37faff576299ff14092b61ed39f2a1c086f672a5

10 files changed, 1104 insertions, 0 deletions

diff --git a/cmds/hid/Android.mk b/cmds/hid/Android.mk
new file mode 100644
index 0000000..ff3691d
--- /dev/null
+++ b/cmds/hid/Android.mk
@@ -0,0 +1,18 @@
+# Copyright 2015 The Android Open Source Project
+#
+LOCAL_PATH:= $(call my-dir)
+
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := $(call all-subdir-java-files)
+LOCAL_MODULE := hid
+LOCAL_JNI_SHARED_LIBRARIES := libhidcommand_jni
+include $(BUILD_JAVA_LIBRARY)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := hid
+LOCAL_SRC_FILES := hid
+LOCAL_MODULE_TAGS := optional
+LOCAL_MODULE_CLASS := EXECUTABLES
+include $(BUILD_PREBUILT)
+
+include $(call all-makefiles-under,$(LOCAL_PATH))
diff --git a/cmds/hid/MODULE_LICENSE_APACHE2 b/cmds/hid/MODULE_LICENSE_APACHE2
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/cmds/hid/MODULE_LICENSE_APACHE2
diff --git a/cmds/hid/NOTICE b/cmds/hid/NOTICE
new file mode 100644
index 0000000..c5b1efa
--- /dev/null
+++ b/cmds/hid/NOTICE
@@ -0,0 +1,190 @@
+
+   Copyright (c) 2005-2008, The Android Open Source Project
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diff --git a/cmds/hid/hid b/cmds/hid/hid
new file mode 100755
index 0000000..2359fcd
--- /dev/null
+++ b/cmds/hid/hid
@@ -0,0 +1,8 @@
+#!/system/bin/sh
+#
+# Script to start "hid" on the device, which has a very rudimentary
+# shell.
+#
+base=/system
+export CLASSPATH=$base/framework/hid.jar
+exec app_process $base/bin com.android.commands.hid.Hid "$@"
diff --git a/cmds/hid/jni/Android.mk b/cmds/hid/jni/Android.mk
new file mode 100644
index 0000000..8163a9d
--- /dev/null
+++ b/cmds/hid/jni/Android.mk
@@ -0,0 +1,23 @@
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := \
+    com_android_commands_hid_Device.cpp
+
+LOCAL_C_INCLUDES := \
+    $(JNI_H_INCLUDE) \
+    frameworks/base/core/jni
+
+LOCAL_SHARED_LIBRARIES := \
+    libandroid_runtime \
+    liblog \
+    libnativehelper \
+    libutils
+
+LOCAL_MODULE := libhidcommand_jni
+LOCAL_MODULE_TAGS := optional
+
+LOCAL_CFLAGS += -Wall
+
+include $(BUILD_SHARED_LIBRARY)
diff --git a/cmds/hid/jni/com_android_commands_hid_Device.cpp b/cmds/hid/jni/com_android_commands_hid_Device.cpp
new file mode 100644
index 0000000..4278e7d
--- /dev/null
+++ b/cmds/hid/jni/com_android_commands_hid_Device.cpp
@@ -0,0 +1,253 @@
+/*
+ * Copyright (C) 2015 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 "HidCommandDevice"
+
+#include "com_android_commands_hid_Device.h"
+
+#include <linux/uhid.h>
+
+#include <fcntl.h>
+#include <cstdio>
+#include <cstring>
+#include <memory>
+#include <unistd.h>
+
+#include <android_runtime/AndroidRuntime.h>
+#include <android_runtime/Log.h>
+#include <android_os_MessageQueue.h>
+#include <core_jni_helpers.h>
+#include <jni.h>
+#include <JNIHelp.h>
+#include <ScopedPrimitiveArray.h>
+#include <ScopedUtfChars.h>
+#include <utils/Log.h>
+#include <utils/Looper.h>
+#include <utils/StrongPointer.h>
+
+namespace android {
+namespace uhid {
+
+static const char* UHID_PATH = "/dev/uhid";
+static const size_t UHID_MAX_NAME_LENGTH = 128;
+
+static struct {
+    jmethodID onDeviceOpen;
+    jmethodID onDeviceError;
+} gDeviceCallbackClassInfo;
+
+static int handleLooperEvents(int fd, int events, void* data) {
+    Device* d = reinterpret_cast<Device*>(data);
+    return d->handleEvents(events);
+}
+
+static void checkAndClearException(JNIEnv* env, const char* methodName) {
+    if (env->ExceptionCheck()) {
+        ALOGE("An exception was thrown by callback '%s'.", methodName);
+        LOGE_EX(env);
+        env->ExceptionClear();
+    }
+}
+
+DeviceCallback::DeviceCallback(JNIEnv* env, jobject callback) :
+    mCallbackObject(env->NewGlobalRef(callback)) { }
+
+DeviceCallback::~DeviceCallback() {
+    JNIEnv* env = AndroidRuntime::getJNIEnv();
+    env->DeleteGlobalRef(mCallbackObject);
+}
+
+void DeviceCallback::onDeviceError() {
+    JNIEnv* env = AndroidRuntime::getJNIEnv();
+    env->CallVoidMethod(mCallbackObject, gDeviceCallbackClassInfo.onDeviceError);
+    checkAndClearException(env, "onDeviceError");
+}
+
+void DeviceCallback::onDeviceOpen() {
+    JNIEnv* env = AndroidRuntime::getJNIEnv();
+    env->CallVoidMethod(mCallbackObject, gDeviceCallbackClassInfo.onDeviceOpen);
+    checkAndClearException(env, "onDeviceOpen");
+}
+
+Device* Device::open(int32_t id, const char* name, int32_t vid, int32_t pid,
+        std::unique_ptr<uint8_t[]> descriptor, size_t descriptorSize,
+        std::unique_ptr<DeviceCallback> callback, sp<Looper> looper) {
+
+    int fd = ::open(UHID_PATH, O_RDWR | O_CLOEXEC);
+    if (fd < 0) {
+        ALOGE("Failed to open uhid: %s", strerror(errno));
+        return nullptr;
+    }
+
+    struct uhid_event ev;
+    memset(&ev, 0, sizeof(ev));
+    ev.type = UHID_CREATE;
+    strncpy((char*)ev.u.create.name, name, UHID_MAX_NAME_LENGTH);
+    ev.u.create.rd_data = descriptor.get();
+    ev.u.create.rd_size = descriptorSize;
+    ev.u.create.bus = BUS_BLUETOOTH;
+    ev.u.create.vendor = vid;
+    ev.u.create.product = pid;
+    ev.u.create.version = 0;
+    ev.u.create.country = 0;
+
+    errno = 0;
+    ssize_t ret = TEMP_FAILURE_RETRY(::write(fd, &ev, sizeof(ev)));
+    if (ret < 0 || ret != sizeof(ev)) {
+        ::close(fd);
+        ALOGE("Failed to create uhid node: %s", strerror(errno));
+        return nullptr;
+    }
+
+    // Wait for the device to actually be created.
+    ret = TEMP_FAILURE_RETRY(::read(fd, &ev, sizeof(ev)));
+    if (ret < 0 || ev.type != UHID_START) {
+        ::close(fd);
+        ALOGE("uhid node failed to start: %s", strerror(errno));
+        return nullptr;
+    }
+
+    return new Device(id, fd, std::move(callback), looper);
+}
+
+Device::Device(int32_t id, int fd, std::unique_ptr<DeviceCallback> callback, sp<Looper> looper) :
+            mId(id), mFd(fd), mDeviceCallback(std::move(callback)), mLooper(looper) {
+    looper->addFd(fd, 0, Looper::EVENT_INPUT, handleLooperEvents, reinterpret_cast<void*>(this));
+}
+
+Device::~Device() {
+    mLooper->removeFd(mFd);
+    struct uhid_event ev;
+    memset(&ev, 0, sizeof(ev));
+    ev.type = UHID_DESTROY;
+    TEMP_FAILURE_RETRY(::write(mFd, &ev, sizeof(ev)));
+    ::close(mFd);
+    mFd = -1;
+}
+
+void Device::sendReport(uint8_t* report, size_t reportSize) {
+    struct uhid_event ev;
+    memset(&ev, 0, sizeof(ev));
+    ev.type = UHID_INPUT;
+    ev.u.input.size = reportSize;
+    memcpy(&ev.u.input.data, report, reportSize);
+    ssize_t ret = TEMP_FAILURE_RETRY(::write(mFd, &ev, sizeof(ev)));
+    if (ret < 0 || ret != sizeof(ev)) {
+        ALOGE("Failed to send hid event: %s", strerror(errno));
+    }
+}
+
+int Device::handleEvents(int events) {
+    if (events & (Looper::EVENT_ERROR | Looper::EVENT_HANGUP)) {
+        ALOGE("uhid node was closed or an error occurred. events=0x%x", events);
+        mDeviceCallback->onDeviceError();
+        return 0;
+    }
+    struct uhid_event ev;
+    ssize_t ret = TEMP_FAILURE_RETRY(::read(mFd, &ev, sizeof(ev)));
+    if (ret < 0) {
+        ALOGE("Failed to read from uhid node: %s", strerror(errno));
+        mDeviceCallback->onDeviceError();
+        return 0;
+    }
+
+    if (ev.type == UHID_OPEN) {
+        mDeviceCallback->onDeviceOpen();
+    }
+
+    return 1;
+}
+
+} // namespace uhid
+
+std::unique_ptr<uint8_t[]> getData(JNIEnv* env, jbyteArray javaArray, size_t& outSize) {
+    ScopedByteArrayRO scopedArray(env, javaArray);
+    outSize = scopedArray.size();
+    std::unique_ptr<uint8_t[]> data(new uint8_t[outSize]);
+    for (size_t i = 0; i < outSize; i++) {
+        data[i] = static_cast<uint8_t>(scopedArray[i]);
+    }
+    return data;
+}
+
+static jlong openDevice(JNIEnv* env, jclass clazz, jstring rawName, jint id, jint vid, jint pid,
+        jbyteArray rawDescriptor, jobject queue, jobject callback) {
+    ScopedUtfChars name(env, rawName);
+    if (name.c_str() == nullptr) {
+        return 0;
+    }
+
+    size_t size;
+    std::unique_ptr<uint8_t[]> desc = getData(env, rawDescriptor, size);
+
+    std::unique_ptr<uhid::DeviceCallback> cb(new uhid::DeviceCallback(env, callback));
+    sp<Looper> looper = android_os_MessageQueue_getMessageQueue(env, queue)->getLooper();
+
+    uhid::Device* d = uhid::Device::open(
+            id, reinterpret_cast<const char*>(name.c_str()), vid, pid,
+            std::move(desc), size, std::move(cb), std::move(looper));
+    return reinterpret_cast<jlong>(d);
+}
+
+static void sendReport(JNIEnv* env, jclass clazz, jlong ptr,jbyteArray rawReport) {
+    size_t size;
+    std::unique_ptr<uint8_t[]> report = getData(env, rawReport, size);
+    uhid::Device* d = reinterpret_cast<uhid::Device*>(ptr);
+    if (d) {
+        d->sendReport(report.get(), size);
+    }
+}
+
+static void closeDevice(JNIEnv* env, jclass clazz, jlong ptr) {
+    uhid::Device* d = reinterpret_cast<uhid::Device*>(ptr);
+    if (d) {
+        delete d;
+    }
+}
+
+static JNINativeMethod sMethods[] = {
+    { "nativeOpenDevice",
+            "(Ljava/lang/String;III[BLandroid/os/MessageQueue;"
+            "Lcom/android/commands/hid/Device$DeviceCallback;)J",
+            reinterpret_cast<void*>(openDevice) },
+    { "nativeSendReport", "(J[B)V", reinterpret_cast<void*>(sendReport) },
+    { "nativeCloseDevice", "(J)V", reinterpret_cast<void*>(closeDevice) },
+};
+
+int register_com_android_commands_hid_Device(JNIEnv* env) {
+    jclass clazz = FindClassOrDie(env, "com/android/commands/hid/Device$DeviceCallback");
+    uhid::gDeviceCallbackClassInfo.onDeviceOpen =
+            GetMethodIDOrDie(env, clazz, "onDeviceOpen", "()V");
+    uhid::gDeviceCallbackClassInfo.onDeviceError=
+            GetMethodIDOrDie(env, clazz, "onDeviceError", "()V");
+    return jniRegisterNativeMethods(env, "com/android/commands/hid/Device",
+            sMethods, NELEM(sMethods));
+}
+
+} // namespace android
+
+jint JNI_OnLoad(JavaVM* jvm, void*) {
+    JNIEnv *env = NULL;
+    if (jvm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6)) {
+        return JNI_ERR;
+    }
+
+    if (android::register_com_android_commands_hid_Device(env) < 0 ){
+        return JNI_ERR;
+    }
+
+    return JNI_VERSION_1_6;
+}
diff --git a/cmds/hid/jni/com_android_commands_hid_Device.h b/cmds/hid/jni/com_android_commands_hid_Device.h
new file mode 100644
index 0000000..6c5899e
--- /dev/null
+++ b/cmds/hid/jni/com_android_commands_hid_Device.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#include <memory>
+
+#include <jni.h>
+#include <utils/Looper.h>
+#include <utils/StrongPointer.h>
+
+namespace android {
+namespace uhid {
+
+class DeviceCallback {
+public:
+    DeviceCallback(JNIEnv* env, jobject callback);
+    ~DeviceCallback();
+
+    void onDeviceOpen();
+    void onDeviceError();
+
+private:
+    jobject mCallbackObject;
+};
+
+class Device {
+public:
+    static Device* open(int32_t id, const char* name, int32_t vid, int32_t pid,
+            std::unique_ptr<uint8_t[]> descriptor, size_t descriptorSize,
+            std::unique_ptr<DeviceCallback> callback, sp<Looper> looper);
+
+    Device(int32_t id, int fd, std::unique_ptr<DeviceCallback> callback, sp<Looper> looper);
+    ~Device();
+
+    void sendReport(uint8_t* report, size_t reportSize);
+    void close();
+
+    int handleEvents(int events);
+
+private:
+    int32_t mId;
+    int mFd;
+    std::unique_ptr<DeviceCallback> mDeviceCallback;
+    sp<Looper> mLooper;
+};
+
+
+} // namespace uhid
+} // namespace android
diff --git a/cmds/hid/src/com/android/commands/hid/Device.java b/cmds/hid/src/com/android/commands/hid/Device.java
new file mode 100644
index 0000000..dbe883b
--- /dev/null
+++ b/cmds/hid/src/com/android/commands/hid/Device.java
@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2015 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 com.android.commands.hid;
+
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.Looper;
+import android.os.Message;
+import android.os.MessageQueue;
+import android.os.SystemClock;
+import android.util.Log;
+
+import com.android.internal.os.SomeArgs;
+
+public class Device {
+    private static final String TAG = "HidDevice";
+
+    // Minimum amount of time to wait before sending input events to a device. Even though we're
+    // guaranteed that the device has been created and opened by the input system, there's still a
+    // window in which the system hasn't started reading events out of it. If a stream of events
+    // begins in during this window (like a button down event) and *then* we start reading, we're
+    // liable to ignore the whole stream.
+    private static final int MIN_WAIT_FOR_FIRST_EVENT = 150;
+
+    private static final int MSG_OPEN_DEVICE = 1;
+    private static final int MSG_SEND_REPORT = 2;
+    private static final int MSG_CLOSE_DEVICE = 3;
+
+
+    private final int mId;
+    private final HandlerThread mThread;
+    private final DeviceHandler mHandler;
+    private long mEventTime;
+
+    private final Object mCond = new Object();
+
+    static {
+        System.loadLibrary("hidcommand_jni");
+    }
+
+    private static native long nativeOpenDevice(String name, int id, int vid, int pid,
+            byte[] descriptor, MessageQueue queue, DeviceCallback callback);
+    private static native void nativeSendReport(long ptr, byte[] data);
+    private static native void nativeCloseDevice(long ptr);
+
+    public Device(int id, String name, int vid, int pid, byte[] descriptor, byte[] report) {
+        mId = id;
+        mThread = new HandlerThread("HidDeviceHandler");
+        mThread.start();
+        mHandler = new DeviceHandler(mThread.getLooper());
+        SomeArgs args = SomeArgs.obtain();
+        args.argi1 = id;
+        args.argi2 = vid;
+        args.argi3 = pid;
+        if (name != null) {
+            args.arg1 = name;
+        } else {
+            args.arg1 = id + ":" + vid + ":" + pid;
+        }
+        args.arg2 = descriptor;
+        args.arg3 = report;
+        mHandler.obtainMessage(MSG_OPEN_DEVICE, args).sendToTarget();
+        mEventTime = SystemClock.uptimeMillis() + MIN_WAIT_FOR_FIRST_EVENT;
+    }
+
+    public void sendReport(byte[] report) {
+        Message msg = mHandler.obtainMessage(MSG_SEND_REPORT, report);
+        mHandler.sendMessageAtTime(msg, mEventTime);
+    }
+
+    public void addDelay(int delay) {
+        mEventTime += delay;
+    }
+
+    public void close() {
+        Message msg = mHandler.obtainMessage(MSG_CLOSE_DEVICE);
+        msg.setAsynchronous(true);
+        mHandler.sendMessageAtTime(msg, mEventTime + 1);
+        try {
+            synchronized (mCond) {
+                mCond.wait();
+            }
+        } catch (InterruptedException ignore) {}
+    }
+
+    private class DeviceHandler extends Handler {
+        private long mPtr;
+        private int mBarrierToken;
+
+        public DeviceHandler(Looper looper) {
+            super(looper);
+        }
+
+        @Override
+        public void handleMessage(Message msg) {
+            switch (msg.what) {
+                case MSG_OPEN_DEVICE:
+                    SomeArgs args = (SomeArgs) msg.obj;
+                    mPtr = nativeOpenDevice((String) args.arg1, args.argi1, args.argi2, args.argi3,
+                            (byte[]) args.arg2, getLooper().myQueue(), new DeviceCallback());
+                    nativeSendReport(mPtr, (byte[]) args.arg3);
+                    pauseEvents();
+                    break;
+                case MSG_SEND_REPORT:
+                    if (mPtr != 0) {
+                        nativeSendReport(mPtr, (byte[]) msg.obj);
+                    } else {
+                        Log.e(TAG, "Tried to send report to closed device.");
+                    }
+                    break;
+                case MSG_CLOSE_DEVICE:
+                    if (mPtr != 0) {
+                        nativeCloseDevice(mPtr);
+                        getLooper().quitSafely();
+                        mPtr = 0;
+                    } else {
+                        Log.e(TAG, "Tried to close already closed device.");
+                    }
+                    synchronized (mCond) {
+                        mCond.notify();
+                    }
+                    break;
+                default:
+                    throw new IllegalArgumentException("Unknown device message");
+            }
+        }
+
+        public void pauseEvents() {
+            mBarrierToken = getLooper().myQueue().postSyncBarrier();
+        }
+
+        public void resumeEvents() {
+            getLooper().myQueue().removeSyncBarrier(mBarrierToken);
+            mBarrierToken = 0;
+        }
+    }
+
+    private class DeviceCallback {
+        public void onDeviceOpen() {
+            mHandler.resumeEvents();
+        }
+
+        public void onDeviceError() {
+            Message msg = mHandler.obtainMessage(MSG_CLOSE_DEVICE);
+            msg.setAsynchronous(true);
+            msg.sendToTarget();
+        }
+    }
+}
diff --git a/cmds/hid/src/com/android/commands/hid/Event.java b/cmds/hid/src/com/android/commands/hid/Event.java
new file mode 100644
index 0000000..c6a37bd
--- /dev/null
+++ b/cmds/hid/src/com/android/commands/hid/Event.java
@@ -0,0 +1,255 @@
+/*
+ * Copyright (C) 2015 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 com.android.commands.hid;
+
+import android.util.JsonReader;
+import android.util.JsonToken;
+import android.util.Log;
+
+import java.io.InputStreamReader;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class Event {
+    private static final String TAG = "HidEvent";
+
+    public static final String COMMAND_REGISTER = "register";
+    public static final String COMMAND_DELAY = "delay";
+    public static final String COMMAND_REPORT = "report";
+
+    private int mId;
+    private String mCommand;
+    private String mName;
+    private byte[] mDescriptor;
+    private int mVid;
+    private int mPid;
+    private byte[] mReport;
+    private int mDuration;
+
+    public int getId() {
+        return mId;
+    }
+
+    public String getCommand() {
+        return mCommand;
+    }
+
+    public String getName() {
+        return mName;
+    }
+
+    public byte[] getDescriptor() {
+        return mDescriptor;
+    }
+
+    public int getVendorId() {
+        return mVid;
+    }
+
+    public int getProductId() {
+        return mPid;
+    }
+
+    public byte[] getReport() {
+        return mReport;
+    }
+
+    public int getDuration() {
+        return mDuration;
+    }
+
+    public String toString() {
+        return "Event{id=" + mId
+            + ", command=" + String.valueOf(mCommand)
+            + ", name=" + String.valueOf(mName)
+            + ", descriptor=" + Arrays.toString(mDescriptor)
+            + ", vid=" + mVid
+            + ", pid=" + mPid
+            + ", report=" + Arrays.toString(mReport)
+            + ", duration=" + mDuration
+            + "}";
+    }
+
+    private static class Builder {
+        private Event mEvent;
+
+        public Builder() {
+            mEvent = new Event();
+        }
+
+        public void setId(int id) {
+            mEvent.mId = id;
+        }
+
+        private void setCommand(String command) {
+            mEvent.mCommand = command;
+        }
+
+        public void setName(String name) {
+            mEvent.mName = name;
+        }
+
+        public void setDescriptor(byte[] descriptor) {
+            mEvent.mDescriptor = descriptor;
+        }
+
+        public void setReport(byte[] report) {
+            mEvent.mReport = report;
+        }
+
+        public void setVid(int vid) {
+            mEvent.mVid = vid;
+        }
+
+        public void setPid(int pid) {
+            mEvent.mPid = pid;
+        }
+
+        public void setDuration(int duration) {
+            mEvent.mDuration = duration;
+        }
+
+        public Event build() {
+            if (mEvent.mId == -1) {
+                throw new IllegalStateException("No event id");
+            } else if (mEvent.mCommand == null) {
+                throw new IllegalStateException("Event does not contain a command");
+            }
+            if (COMMAND_REGISTER.equals(mEvent.mCommand)) {
+                if (mEvent.mDescriptor == null) {
+                    throw new IllegalStateException("Device registration is missing descriptor");
+                }
+            } else if (COMMAND_DELAY.equals(mEvent.mCommand)) {
+                if (mEvent.mDuration <= 0) {
+                    throw new IllegalStateException("Delay has missing or invalid duration");
+                }
+            } else if (COMMAND_REPORT.equals(mEvent.mCommand)) {
+                if (mEvent.mReport == null) {
+                    throw new IllegalStateException("Report command is missing report data");
+                }
+            }
+            return mEvent;
+        }
+    }
+
+    public static class Reader {
+        private JsonReader mReader;
+
+        public Reader(InputStreamReader in) {
+            mReader = new JsonReader(in);
+            mReader.setLenient(true);
+        }
+
+        public Event getNextEvent() throws IOException {
+            Event e = null;
+            while (e == null && mReader.peek() != JsonToken.END_DOCUMENT) {
+                Event.Builder eb = new Event.Builder();
+                try {
+                    mReader.beginObject();
+                    while (mReader.hasNext()) {
+                        String name = mReader.nextName();
+                        switch (name) {
+                            case "id":
+                                eb.setId(readInt());
+                                break;
+                            case "command":
+                                eb.setCommand(mReader.nextString());
+                                break;
+                            case "descriptor":
+                                eb.setDescriptor(readData());
+                                break;
+                            case "name":
+                                eb.setName(mReader.nextString());
+                                break;
+                            case "vid":
+                                eb.setVid(readInt());
+                                break;
+                            case "pid":
+                                eb.setPid(readInt());
+                                break;
+                            case "report":
+                                eb.setReport(readData());
+                                break;
+                            case "duration":
+                                eb.setDuration(readInt());
+                                break;
+                            default:
+                                mReader.skipValue();
+                        }
+                    }
+                    mReader.endObject();
+                } catch (IllegalStateException ex) {
+                    error("Error reading in object, ignoring.", ex);
+                    consumeRemainingElements();
+                    mReader.endObject();
+                    continue;
+                }
+                e = eb.build();
+            }
+
+            return e;
+        }
+
+        private byte[] readData() throws IOException {
+            ArrayList<Integer> data = new ArrayList<Integer>();
+            try {
+                mReader.beginArray();
+                while (mReader.hasNext()) {
+                    data.add(Integer.decode(mReader.nextString()));
+                }
+                mReader.endArray();
+            } catch (IllegalStateException|NumberFormatException e) {
+                consumeRemainingElements();
+                mReader.endArray();
+                throw new IllegalStateException("Encountered malformed data.", e);
+            }
+            byte[] rawData = new byte[data.size()];
+            for (int i = 0; i < data.size(); i++) {
+                int d = data.get(i);
+                if ((d & 0xFF) != d) {
+                    throw new IllegalStateException("Invalid data, all values must be byte-sized");
+                }
+                rawData[i] = (byte)d;
+            }
+            return rawData;
+        }
+
+        private int readInt() throws IOException {
+            String val = mReader.nextString();
+            return Integer.decode(val);
+        }
+
+        private void consumeRemainingElements() throws IOException {
+            while (mReader.hasNext()) {
+                mReader.skipValue();
+            }
+        }
+    }
+
+    private static void error(String msg) {
+        error(msg, null);
+    }
+
+    private static void error(String msg, Exception e) {
+        System.out.println(msg);
+        Log.e(TAG, msg);
+        if (e != null) {
+            Log.e(TAG, Log.getStackTraceString(e));
+        }
+    }
+}
diff --git a/cmds/hid/src/com/android/commands/hid/Hid.java b/cmds/hid/src/com/android/commands/hid/Hid.java
new file mode 100644
index 0000000..976a782
--- /dev/null
+++ b/cmds/hid/src/com/android/commands/hid/Hid.java
@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2015 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 com.android.commands.hid;
+
+import android.os.SystemClock;
+import android.util.JsonReader;
+import android.util.JsonToken;
+import android.util.Log;
+import android.util.SparseArray;
+
+import libcore.io.IoUtils;
+
+import java.io.BufferedInputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.util.ArrayList;
+
+public class Hid {
+    private static final String TAG = "HID";
+
+    private final Event.Reader mReader;
+    private final SparseArray<Device> mDevices;
+
+    private static void usage() {
+        error("Usage: hid [FILE]");
+    }
+
+    public static void main(String[] args) {
+        if (args.length != 1) {
+            usage();
+            System.exit(1);
+        }
+
+        InputStream stream = null;
+        try {
+            if (args[0].equals("-")) {
+                stream = System.in;
+            } else {
+                File f = new File(args[0]);
+                stream = new FileInputStream(f);
+            }
+            (new Hid(stream)).run();
+        } catch (Exception e) {
+            error("HID injection failed.", e);
+            System.exit(1);
+        } finally {
+            IoUtils.closeQuietly(stream);
+        }
+    }
+
+    private Hid(InputStream in) {
+        mDevices = new SparseArray<Device>();
+        try {
+            mReader = new Event.Reader(new InputStreamReader(in, "UTF-8"));
+        } catch (UnsupportedEncodingException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private void run() {
+        try {
+            Event e = null;
+            while ((e = mReader.getNextEvent()) != null) {
+                process(e);
+            }
+        } catch (IOException ex) {
+            error("Error reading in events.", ex);
+        }
+
+        for (int i = 0; i < mDevices.size(); i++) {
+            mDevices.valueAt(i).close();
+        }
+    }
+
+
+    private void process(Event e) {
+        final int index = mDevices.indexOfKey(e.getId());
+        if (index >= 0) {
+            Device d = mDevices.valueAt(index);
+            if (Event.COMMAND_DELAY.equals(e.getCommand())) {
+                d.addDelay(e.getDuration());
+            } else if (Event.COMMAND_REPORT.equals(e.getCommand())) {
+                d.sendReport(e.getReport());
+            } else {
+                error("Unknown command \"" + e.getCommand() + "\". Ignoring event.");
+            }
+        } else {
+            registerDevice(e);
+        }
+    }
+
+    private void registerDevice(Event e) {
+        if (!Event.COMMAND_REGISTER.equals(e.getCommand())) {
+            throw new IllegalStateException(
+                    "Tried to send command \"" + e.getCommand() + "\" to an unregistered device!");
+        }
+        int id = e.getId();
+        Device d = new Device(id, e.getName(), e.getVendorId(), e.getProductId(),
+                e.getDescriptor(), e.getReport());
+        mDevices.append(id, d);
+    }
+
+    private static void error(String msg) {
+        error(msg, null);
+    }
+
+    private static void error(String msg, Exception e) {
+        System.out.println(msg);
+        Log.e(TAG, msg);
+        if (e != null) {
+            Log.e(TAG, Log.getStackTraceString(e));
+        }
+    }
+}