Avoid entering an infinite loop in PackageManagerBackupAgent#onRestore

When the PackageManagerBackupAgent restores an old backup that does not
have an ancestral record version and the backup contains a package that
does not have any signatures it will enter an infinite loop. This
happens because it calls `continue` without reading the next key/value
pair in the backup.

Test: atest PackageManagerBackupAgentTest
Bug: 330708733
Change-Id: Ifb71293b75ccb68dc7e721593f04128417360491

1 files changed, 8 insertions, 8 deletions

diff --git a/services/backup/java/com/android/server/backup/PackageManagerBackupAgent.java b/services/backup/java/com/android/server/backup/PackageManagerBackupAgent.java
index c3d97904e430..52108bf1568d 100644
--- a/services/backup/java/com/android/server/backup/PackageManagerBackupAgent.java
+++ b/services/backup/java/com/android/server/backup/PackageManagerBackupAgent.java
@@ -781,6 +781,9 @@ public class PackageManagerBackupAgent extends BackupAgent {
                                 "Not restoring package "
                                         + key
                                         + " since it appears to have no signatures.");
+                        if (!data.readNextHeader()) {
+                            break;
+                        }
                         continue;
                     }
 
@@ -790,18 +793,15 @@ public class PackageManagerBackupAgent extends BackupAgent {
                     sigMap.put(key, new Metadata(versionCode, sigs));
                 }
 
-                boolean readNextHeader = data.readNextHeader();
-                if (!readNextHeader) {
-                    if (DEBUG) {
-                        Slog.v(
-                                TAG,
-                                "LegacyRestoreDataConsumer:"
-                                        + " we're done reading all the headers");
-                    }
+                if (!data.readNextHeader()) {
                     break;
                 }
             }
 
+            if (DEBUG) {
+                Slog.v(TAG, "LegacyRestoreDataConsumer:" + " we're done reading all the headers");
+            }
+
             // On successful completion, cache the signature map for the Backup Manager to use
             mRestoredSignatures = sigMap;
         }