Do not force endDocument for domain verify settings

Removes the endDocument call so the serializer can be used as a child
of a larger group. Instead calls flush and assumes all usages will
close tags appropriately.

This usage is incorrect regardless, but endDocument itself is broken
and does not behave the same depending on which XmlSerialier
implementation is being used. Which is why this bug never appeared
during testing/development.

Bug: 180838875
Bug: 181813200

Test: manual, debug linked Bug
Test: atest DomainVerificationPersistenceTest

Change-Id: I50e27817e526d2cbcc0efbcc3ffdfffa53886f0f

services/core/java/com/android/server/pm/SettingsXml.java

@@ -83,7 +83,7 @@ public class SettingsXml {
         @Override
         public void close() throws IOException {
             mWriteSection.closeCompletely();
-            mXmlSerializer.endDocument();
+            mXmlSerializer.flush();
         }
     }
 

services/core/java/com/android/server/pm/verify/domain/DomainVerificationLegacySettings.java

@@ -32,7 +32,6 @@ import com.android.server.pm.SettingsXml;
 import org.xmlpull.v1.XmlPullParserException;
 
 import java.io.IOException;
-import java.util.Map;
 
 /**
  * Reads and writes the old {@link android.content.pm.IntentFilterVerificationInfo} so that it can

services/tests/PackageManagerServiceTests/unit/src/com/android/server/pm/test/verify/domain/DomainVerificationPersistenceTest.kt

@@ -30,6 +30,7 @@ import com.google.common.truth.Truth.assertWithMessage
 import org.junit.Rule
 import org.junit.Test
 import org.junit.rules.TemporaryFolder
+import org.xmlpull.v1.XmlPullParser
 import java.io.File
 import java.nio.charset.StandardCharsets
 import java.util.UUID
@@ -41,21 +42,41 @@ class DomainVerificationPersistenceTest {
 
         internal fun File.writeXml(block: (serializer: TypedXmlSerializer) -> Unit) = apply {
             outputStream().use {
-                // Explicitly use string based XML so it can printed in the test failure output
-                Xml.newFastSerializer()
+                // This must use the binary serializer the mirror the production behavior, as
+                // there are slight differences with the string based one.
+                Xml.newBinarySerializer()
                     .apply {
                         setOutput(it, StandardCharsets.UTF_8.name())
                         startDocument(null, true)
                         setFeature("http://xmlpull.org/v1/doc/features.html#indent-output", true)
+                        // Write a wrapping tag to ensure the domain verification settings didn't
+                        // close out the document, allowing other settings to be written
+                        startTag(null, "wrapper-tag")
                     }
                     .apply(block)
+                    .apply {
+                        startTag(null, "trailing-tag")
+                        endTag(null, "trailing-tag")
+                        endTag(null, "wrapper-tag")
+                    }
                     .endDocument()
             }
         }
 
         internal fun <T> File.readXml(block: (parser: TypedXmlPullParser) -> T) =
             inputStream().use {
-                block(Xml.resolvePullParser(it))
+                val parser = Xml.resolvePullParser(it)
+                assertThat(parser.nextTag()).isEqualTo(XmlPullParser.START_TAG)
+                assertThat(parser.name).isEqualTo("wrapper-tag")
+                assertThat(parser.nextTag()).isEqualTo(XmlPullParser.START_TAG)
+                block(parser).also {
+                    assertThat(parser.nextTag()).isEqualTo(XmlPullParser.START_TAG)
+                    assertThat(parser.name).isEqualTo("trailing-tag")
+                    assertThat(parser.nextTag()).isEqualTo(XmlPullParser.END_TAG)
+                    assertThat(parser.name).isEqualTo("trailing-tag")
+                    assertThat(parser.nextTag()).isEqualTo(XmlPullParser.END_TAG)
+                    assertThat(parser.name).isEqualTo("wrapper-tag")
+                }
             }
     }