Merge "Don't write widget metadata to backup unless it's new/changed" into lmp-mr1-dev
diff --git a/services/backup/java/com/android/server/backup/BackupManagerService.java b/services/backup/java/com/android/server/backup/BackupManagerService.java
index 7d085a3..289152b 100644
--- a/services/backup/java/com/android/server/backup/BackupManagerService.java
+++ b/services/backup/java/com/android/server/backup/BackupManagerService.java
@@ -130,6 +130,7 @@
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 @@
}
}
+ // 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 @@
}
// 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.