Clean up USB Manager and fix ADB.

Moved functions which parse the USB functions list into one common
place on UsbManager.

Deleted the no longer supported USB_FUNCTION_MASS_STORAGE.

Ensured that the UserManager.DISALLOW_USB_FILE_TRANSFER rule is
consistently applied during user switch and when changing the
current USB functions and make sure it only affects MTP and PTP.

Collapsed the boot completed and user switched receivers to
ensure consistent ordering of side-effects.

Validate the list of functions passed to setCurrentFunction() so
that the separation of concerns is clearer.  It was somewhat
ambiguous as to whether functions such as ADB could / should be
enabled through that interface.  Improved the docs for clarity.

Fixed a bunch of broken stuff related to the USB config
persistent property (list of default functions) that could cause
ADB and other functions to not work at all.  Added new failsafes
to ensure that we reliably get back into a happy state.

Bug: 22206076
Change-Id: I02915ddfce7193a8f67a14f0d76bab22fc575dfa

2 files changed, 89 insertions, 44 deletions

diff --git a/core/java/android/hardware/usb/IUsbManager.aidl b/core/java/android/hardware/usb/IUsbManager.aidl
index 31a6a96..0fe112c 100644
--- a/core/java/android/hardware/usb/IUsbManager.aidl
+++ b/core/java/android/hardware/usb/IUsbManager.aidl
@@ -82,6 +82,9 @@ interface IUsbManager
     /* Clears default preferences and permissions for the package */
     void clearDefaults(String packageName, int userId);
 
+    /* Returns true if the specified USB function is enabled. */
+    boolean isFunctionEnabled(String function);
+
     /* Sets the current USB function. */
     void setCurrentFunction(String function);
 
diff --git a/core/java/android/hardware/usb/UsbManager.java b/core/java/android/hardware/usb/UsbManager.java
index c83f466..f58b9d6 100644
--- a/core/java/android/hardware/usb/UsbManager.java
+++ b/core/java/android/hardware/usb/UsbManager.java
@@ -22,7 +22,6 @@ import android.content.Context;
 import android.os.Bundle;
 import android.os.ParcelFileDescriptor;
 import android.os.RemoteException;
-import android.os.SystemProperties;
 import android.util.Log;
 
 import java.util.HashMap;
@@ -54,8 +53,6 @@ public class UsbManager {
      * <li> {@link #USB_CONNECTED} boolean indicating whether USB is connected or disconnected.
      * <li> {@link #USB_CONFIGURED} boolean indicating whether USB is configured.
      * currently zero if not configured, one for configured.
-     * <li> {@link #USB_FUNCTION_MASS_STORAGE} boolean extra indicating whether the
-     * mass storage function is enabled
      * <li> {@link #USB_FUNCTION_ADB} boolean extra indicating whether the
      * adb function is enabled
      * <li> {@link #USB_FUNCTION_RNDIS} boolean extra indicating whether the
@@ -152,12 +149,13 @@ public class UsbManager {
     public static final String USB_DATA_UNLOCKED = "unlocked";
 
     /**
-     * Name of the USB mass storage USB function.
-     * Used in extras for the {@link #ACTION_USB_STATE} broadcast
+     * A placeholder indicating that no USB function is being specified.
+     * Used to distinguish between selecting no function vs. the default function in
+     * {@link #setCurrentFunction(String)}.
      *
      * {@hide}
      */
-    public static final String USB_FUNCTION_MASS_STORAGE = "mass_storage";
+    public static final String USB_FUNCTION_NONE = "none";
 
     /**
      * Name of the adb USB function.
@@ -218,15 +216,14 @@ public class UsbManager {
     /**
      * Name of extra for {@link #ACTION_USB_DEVICE_ATTACHED} and
      * {@link #ACTION_USB_DEVICE_DETACHED} broadcasts
-     * containing the UsbDevice object for the device.
+     * containing the {@link UsbDevice} object for the device.
      */
-
     public static final String EXTRA_DEVICE = "device";
 
     /**
      * Name of extra for {@link #ACTION_USB_ACCESSORY_ATTACHED} and
      * {@link #ACTION_USB_ACCESSORY_DETACHED} broadcasts
-     * containing the UsbAccessory object for the accessory.
+     * containing the {@link UsbAccessory} object for the accessory.
      */
     public static final String EXTRA_ACCESSORY = "accessory";
 
@@ -238,23 +235,6 @@ public class UsbManager {
      */
     public static final String EXTRA_PERMISSION_GRANTED = "permission";
 
-    /**
-     * The persistent property which stores whether adb is enabled or not. Other values are ignored.
-     * Previously this value stored non-adb settings, but not anymore.
-     * TODO: rename this to something adb specific, rather than using usb.
-     *
-     * {@hide}
-     */
-    public static final String ADB_PERSISTENT_PROPERTY = "persist.sys.usb.config";
-
-    /**
-     * The non-persistent property which stores the current USB settings.
-     *
-     * {@hide}
-     */
-    public static final String USB_SETTINGS_PROPERTY = "sys.usb.config";
-
-
     private final Context mContext;
     private final IUsbManager mService;
 
@@ -437,31 +417,44 @@ public class UsbManager {
         }
     }
 
-    private static boolean propertyContainsFunction(String property, String function) {
-        String functions = SystemProperties.get(property, "");
-        int index = functions.indexOf(function);
-        if (index < 0) return false;
-        if (index > 0 && functions.charAt(index - 1) != ',') return false;
-        int charAfter = index + function.length();
-        if (charAfter < functions.length() && functions.charAt(charAfter) != ',') return false;
-        return true;
-    }
-
     /**
-     * Returns true if the specified USB function is currently enabled.
+     * Returns true if the specified USB function is currently enabled when in device mode.
+     * <p>
+     * USB functions represent interfaces which are published to the host to access
+     * services offered by the device.
+     * </p>
      *
      * @param function name of the USB function
-     * @return true if the USB function is enabled.
+     * @return true if the USB function is enabled
      *
      * {@hide}
      */
     public boolean isFunctionEnabled(String function) {
-        return propertyContainsFunction(USB_SETTINGS_PROPERTY, function);
+        try {
+            return mService.isFunctionEnabled(function);
+        } catch (RemoteException e) {
+            Log.e(TAG, "RemoteException in setCurrentFunction", e);
+            return false;
+        }
     }
 
     /**
-     * Sets the current USB function.
-     * If function is null, then the current function is set to the default function.
+     * Sets the current USB function when in device mode.
+     * <p>
+     * USB functions represent interfaces which are published to the host to access
+     * services offered by the device.
+     * </p><p>
+     * This method is intended to select among primary USB functions.  The system may
+     * automatically activate additional functions such as {@link #USB_FUNCTION_ADB}
+     * or {@link #USB_FUNCTION_ACCESSORY} based on other settings and states.
+     * </p><p>
+     * The allowed values are: {@link #USB_FUNCTION_NONE}, {@link #USB_FUNCTION_AUDIO_SOURCE},
+     * {@link #USB_FUNCTION_MIDI}, {@link #USB_FUNCTION_MTP}, {@link #USB_FUNCTION_PTP},
+     * or {@link #USB_FUNCTION_RNDIS}.
+     * </p><p>
+     * Note: This function is asynchronous and may fail silently without applying
+     * the requested changes.
+     * </p>
      *
      * @param function name of the USB function, or null to restore the default function
      *
@@ -477,8 +470,9 @@ public class UsbManager {
 
     /**
      * Sets whether USB data (for example, MTP exposed pictures) should be made available
-     * on the USB connection. Unlocking usb data should only be done with user involvement,
-     * since exposing pictures or other data could leak sensitive user information.
+     * on the USB connection when in device mode. Unlocking usb data should only be done with
+     * user involvement, since exposing pictures or other data could leak sensitive
+     * user information.
      *
      * {@hide}
      */
@@ -491,7 +485,8 @@ public class UsbManager {
     }
 
     /**
-     * Returns {@code true} iff access to sensitive USB data is currently allowed.
+     * Returns {@code true} iff access to sensitive USB data is currently allowed when
+     * in device mode.
      *
      * {@hide}
      */
@@ -504,4 +499,51 @@ public class UsbManager {
         return false;
     }
 
+    /** @hide */
+    public static String addFunction(String functions, String function) {
+        if ("none".equals(functions)) {
+            return function;
+        }
+        if (!containsFunction(functions, function)) {
+            if (functions.length() > 0) {
+                functions += ",";
+            }
+            functions += function;
+        }
+        return functions;
+    }
+
+    /** @hide */
+    public static String removeFunction(String functions, String function) {
+        String[] split = functions.split(",");
+        for (int i = 0; i < split.length; i++) {
+            if (function.equals(split[i])) {
+                split[i] = null;
+            }
+        }
+        if (split.length == 1 && split[0] == null) {
+            return "none";
+        }
+        StringBuilder builder = new StringBuilder();
+        for (int i = 0; i < split.length; i++) {
+            String s = split[i];
+            if (s != null) {
+                if (builder.length() > 0) {
+                    builder.append(",");
+                }
+                builder.append(s);
+            }
+        }
+        return builder.toString();
+    }
+
+    /** @hide */
+    public static boolean containsFunction(String functions, String function) {
+        int index = functions.indexOf(function);
+        if (index < 0) return false;
+        if (index > 0 && functions.charAt(index - 1) != ',') return false;
+        int charAfter = index + function.length();
+        if (charAfter < functions.length() && functions.charAt(charAfter) != ',') return false;
+        return true;
+    }
 }