Merge "Don't write widget metadata to backup unless it's new/changed" into lmp-mr1-dev (7651dcb9) · Commits · e / os / android_frameworks_base

services/backup/java/com/android/server/backup/BackupManagerService.java

+80 −11

Original line number	Diff line number	Diff line
		@@ -130,6 +130,7 @@ import java.util.Iterator;
		import java.util.List;
		import java.util.Map;
		import java.util.Map.Entry;
		import java.util.Objects;
		import java.util.Random;
		import java.util.Set;
		import java.util.TreeMap;
		@@ -2695,6 +2696,84 @@ public class BackupManagerService {
		}
		}

		// SHA-1 a byte array and return the result in hex
		private String SHA1Checksum(byte[] input) {
		final byte[] checksum;
		try {
		MessageDigest md = MessageDigest.getInstance("SHA-1");
		checksum = md.digest(input);
		} catch (NoSuchAlgorithmException e) {
		Slog.e(TAG, "Unable to use SHA-1!");
		return "00";
		}

		StringBuffer sb = new StringBuffer(checksum.length * 2);
		for (int i = 0; i < checksum.length; i++) {
		sb.append(Integer.toHexString(checksum[i]));
		}
		return sb.toString();
		}

		private void writeWidgetPayloadIfAppropriate(FileDescriptor fd, String pkgName)
		throws IOException {
		byte[] widgetState = AppWidgetBackupBridge.getWidgetState(pkgName,
		UserHandle.USER_OWNER);
		// has the widget state changed since last time?
		final File widgetFile = new File(mStateDir, pkgName + "_widget");
		final boolean priorStateExists = widgetFile.exists();

		if (MORE_DEBUG) {
		if (priorStateExists \|\| widgetState != null) {
		Slog.i(TAG, "Checking widget update: state=" + (widgetState != null)
		+ " prior=" + priorStateExists);
		}
		}

		if (!priorStateExists && widgetState == null) {
		// no prior state, no new state => nothing to do
		return;
		}

		// if the new state is not null, we might need to compare checksums to
		// determine whether to update the widget blob in the archive. If the
		// widget state is null, we know a priori at this point that we simply
		// need to commit a deletion for it.
		String newChecksum = null;
		if (widgetState != null) {
		newChecksum = SHA1Checksum(widgetState);
		if (priorStateExists) {
		final String priorChecksum;
		try (
		FileInputStream fin = new FileInputStream(widgetFile);
		DataInputStream in = new DataInputStream(fin)
		) {
		priorChecksum = in.readUTF();
		}
		if (Objects.equals(newChecksum, priorChecksum)) {
		// Same checksum => no state change => don't rewrite the widget data
		return;
		}
		}
		} // else widget state became empty, so we need to commit a deletion

		BackupDataOutput out = new BackupDataOutput(fd);
		if (widgetState != null) {
		try (
		FileOutputStream fout = new FileOutputStream(widgetFile);
		DataOutputStream stateOut = new DataOutputStream(fout)
		) {
		stateOut.writeUTF(newChecksum);
		}

		out.writeEntityHeader(KEY_WIDGET_STATE, widgetState.length);
		out.writeEntityData(widgetState, widgetState.length);
		} else {
		// Widget state for this app has been removed; commit a deletion
		out.writeEntityHeader(KEY_WIDGET_STATE, -1);
		widgetFile.delete();
		}
		}

		@Override
		public void operationComplete() {
		// Okay, the agent successfully reported back to us!
		@@ -2733,17 +2812,7 @@ public class BackupManagerService {
		}

		// Piggyback the widget state payload, if any
		BackupDataOutput out = new BackupDataOutput(fd);
		byte[] widgetState = AppWidgetBackupBridge.getWidgetState(pkgName,
		UserHandle.USER_OWNER);
		if (widgetState != null) {
		out.writeEntityHeader(KEY_WIDGET_STATE, widgetState.length);
		out.writeEntityData(widgetState, widgetState.length);
		} else {
		// No widget state for this app, but push a 'delete' operation for it
		// in case they're trying to play games with the payload.
		out.writeEntityHeader(KEY_WIDGET_STATE, -1);
		}
		writeWidgetPayloadIfAppropriate(fd, pkgName);
		} catch (IOException e) {
		// Hard disk error; recovery/failure policy TBD. For now roll back,
		// but we may want to consider this a transport-level failure (i.e.