Merge changes I17264f0e,I0581978f

* changes:
  Limit transcoding size workaround to windows
  Workaround to fixup MTP transcode file size

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;
         }

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();
+    }
 }

media/java/android/mtp/MtpStorageManager.java

@@ -18,7 +18,11 @@ package android.mtp;
 
 import android.media.MediaFile;
 import android.os.FileObserver;
+import android.os.SystemProperties;
 import android.os.storage.StorageVolume;
+import android.system.ErrnoException;
+import android.system.Os;
+import android.system.StructStat;
 import android.util.Log;
 
 import com.android.internal.util.Preconditions;
@@ -35,6 +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
@@ -199,7 +204,38 @@ public class MtpStorageManager {
         }
 
         public long getSize() {
-            return mIsDir ? 0 : getPath().toFile().length();
+            return mIsDir ? 0 : maybeApplyTranscodeLengthWorkaround(getPath().toFile().length());
+        }
+
+        private long maybeApplyTranscodeLengthWorkaround(long length) {
+            // Windows truncates transferred files to the size advertised in the object property.
+            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).
+                return length * 2;
+            }
+            return length;
+        }
+
+        private boolean isTranscodeMtpEnabled() {
+            return SystemProperties.getBoolean("sys.fuse.transcode_mtp", false);
+        }
+
+        private boolean isFileTranscodeSupported() {
+            // Check if the file supports transcoding by reading the |st_nlinks| struct stat
+            // field. This will be > 1 if the file supports transcoding. The FUSE daemon
+            // sets the field accordingly to enable the MTP stack workaround some Windows OS
+            // MTP client bug where they ignore the size returned as part of getting the MTP
+            // object, see MtpServer#doGetObject.
+            final Path path = getPath();
+            try {
+                StructStat stat = Os.stat(path.toString());
+                return stat.st_nlink > 1;
+            } catch (ErrnoException e) {
+                Log.w(TAG, "Failed to stat path: " + getPath() + ". Ignoring transcoding.");
+                return false;
+            }
         }
 
         public Path getPath() {
@@ -420,10 +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;
     }

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