Limit transcoding size workaround to windows

Test: Connect android to windows through usbc.
      Enable mtp, then enable the transcoding option.
      Copy H265 video from the camera folder to windows' desktop.
      Transcoded H264 video plays correctly in WMPcorrectly.

Bug: 184117074
Bug: 190422448
Change-Id: I17264f0ee3e742315569d4c50817b1da7f3f2eb4

4 files changed, 32 insertions, 11 deletions

diff --git a/media/java/android/mtp/MtpDatabase.java b/media/java/android/mtp/MtpDatabase.java
index d8f48c2cf0c6..20d711cf4c54 100755
--- a/media/java/android/mtp/MtpDatabase.java
+++ b/media/java/android/mtp/MtpDatabase.java
@@ -103,6 +103,7 @@ public class MtpDatabase implements AutoCloseable {
     private int mDeviceType;
     private String mHostType;
     private boolean mSkipThumbForHost = false;
+    private volatile boolean mHostIsWindows = false;
 
     private MtpServer mServer;
     private MtpStorageManager mManager;
@@ -358,7 +359,7 @@ public class MtpDatabase implements AutoCloseable {
     }
 
     public void addStorage(StorageVolume storage) {
-        MtpStorage mtpStorage = mManager.addMtpStorage(storage);
+        MtpStorage mtpStorage = mManager.addMtpStorage(storage, () -> mHostIsWindows);
         mStorageMap.put(storage.getPath(), mtpStorage);
         if (mServer != null) {
             mServer.addStorage(mtpStorage);
@@ -413,6 +414,7 @@ public class MtpDatabase implements AutoCloseable {
         }
         mHostType = "";
         mSkipThumbForHost = false;
+        mHostIsWindows = false;
     }
 
     @VisibleForNative
@@ -736,10 +738,12 @@ public class MtpDatabase implements AutoCloseable {
                         : MtpConstants.RESPONSE_GENERAL_ERROR);
             case MtpConstants.DEVICE_PROPERTY_SESSION_INITIATOR_VERSION_INFO:
                 mHostType = stringValue;
+                Log.d(TAG, "setDeviceProperty." + Integer.toHexString(property)
+                        + "=" + stringValue);
                 if (stringValue.startsWith("Android/")) {
-                    Log.d(TAG, "setDeviceProperty." + Integer.toHexString(property)
-                            + "=" + stringValue);
                     mSkipThumbForHost = true;
+                } else if (stringValue.startsWith("Windows/")) {
+                    mHostIsWindows = true;
                 }
                 return MtpConstants.RESPONSE_OK;
         }
diff --git a/media/java/android/mtp/MtpStorage.java b/media/java/android/mtp/MtpStorage.java
index 88c32a3ea72b..a3754e90a875 100644
--- a/media/java/android/mtp/MtpStorage.java
+++ b/media/java/android/mtp/MtpStorage.java
@@ -19,6 +19,8 @@ package android.mtp;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.os.storage.StorageVolume;
 
+import java.util.function.Supplier;
+
 /**
  * This class represents a storage unit on an MTP device.
  * Used only for MTP support in USB responder mode.
@@ -33,14 +35,16 @@ public class MtpStorage {
     private final boolean mRemovable;
     private final long mMaxFileSize;
     private final String mVolumeName;
+    private final Supplier<Boolean> mIsHostWindows;
 
-    public MtpStorage(StorageVolume volume, int storageId) {
+    public MtpStorage(StorageVolume volume, int storageId, Supplier<Boolean> isHostWindows) {
         mStorageId = storageId;
         mPath = volume.getPath();
         mDescription = volume.getDescription(null);
         mRemovable = volume.isRemovable();
         mMaxFileSize = volume.getMaxFileSize();
         mVolumeName = volume.getMediaStoreVolumeName();
+        mIsHostWindows = isHostWindows;
     }
 
     /**
@@ -93,4 +97,13 @@ public class MtpStorage {
     public String getVolumeName() {
         return mVolumeName;
     }
+
+    /**
+     * Returns true if the mtp host of this storage is Windows.
+     *
+     * @return is host Windows
+     */
+    public boolean isHostWindows() {
+        return mIsHostWindows.get();
+    }
 }
diff --git a/media/java/android/mtp/MtpStorageManager.java b/media/java/android/mtp/MtpStorageManager.java
index fd3741ebec23..e9426cf2ce31 100644
--- a/media/java/android/mtp/MtpStorageManager.java
+++ b/media/java/android/mtp/MtpStorageManager.java
@@ -39,6 +39,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.function.Supplier;
 
 /**
  * MtpStorageManager provides functionality for listing, tracking, and notifying MtpServer of
@@ -208,7 +209,7 @@ public class MtpStorageManager {
 
         private long maybeApplyTranscodeLengthWorkaround(long length) {
             // Windows truncates transferred files to the size advertised in the object property.
-            if (isTranscodeMtpEnabled() && isFileTranscodeSupported()) {
+            if (mStorage.isHostWindows() && isTranscodeMtpEnabled() && isFileTranscodeSupported()) {
                 // If the file supports transcoding, we double the returned size to accommodate
                 // the increase in size from transcoding to AVC. This is the same heuristic
                 // applied in the FUSE daemon (MediaProvider).
@@ -455,10 +456,12 @@ public class MtpStorageManager {
      * @param volume Storage to add.
      * @return the associated MtpStorage
      */
-    public synchronized MtpStorage addMtpStorage(StorageVolume volume) {
+    public synchronized MtpStorage addMtpStorage(StorageVolume volume,
+                                                 Supplier<Boolean> isHostWindows) {
         int storageId = ((getNextStorageId() & 0x0000FFFF) << 16) + 1;
-        MtpStorage storage = new MtpStorage(volume, storageId);
-        MtpObject root = new MtpObject(storage.getPath(), storageId, storage, null, true);
+        MtpStorage storage = new MtpStorage(volume, storageId, isHostWindows);
+        MtpObject root = new MtpObject(storage.getPath(), storageId, storage, /* parent= */ null,
+                                       /* isDir= */ true);
         mRoots.put(storageId, root);
         return storage;
     }
diff --git a/media/tests/MtpTests/src/android/mtp/MtpStorageManagerTest.java b/media/tests/MtpTests/src/android/mtp/MtpStorageManagerTest.java
index fdf65823b1f3..eb357f67caea 100644
--- a/media/tests/MtpTests/src/android/mtp/MtpStorageManagerTest.java
+++ b/media/tests/MtpTests/src/android/mtp/MtpStorageManagerTest.java
@@ -159,10 +159,11 @@ public class MtpStorageManagerTest {
                 Log.d(TAG, "sendObjectInfoChanged: " + id);
                 objectsInfoChanged.add(id);
             }
-        }, null);
+        }, /* subdirectories= */ null);
 
-        mainMtpStorage = manager.addMtpStorage(mainStorage);
-        secondaryMtpStorage = manager.addMtpStorage(secondaryStorage);
+        mainMtpStorage = manager.addMtpStorage(mainStorage, /* isHostWindows= */ () -> false);
+        secondaryMtpStorage = manager.addMtpStorage(secondaryStorage,
+                                                    /* isHostWindows= */ () -> false);
     }
 
     @After