AAPT2: Flatten AndroidManifest.xml stringpool in UTF16

A few OEM devices have introduced a memory corruption bug
that is only triggered when an application's AndroidManifest.xml
uses UTF8 string pools. Workaround this by only encoding
AndroidManifest.xml with UTF16 strings.

Bug: 64434571
Test: manual
Change-Id: I2ee50d1b2b5942d971ef2a544c878de63f67c652

tools/aapt2/cmd/Link.cpp

@@ -251,10 +251,11 @@ class FeatureSplitSymbolTableDelegate : public DefaultSymbolTableDelegate {
 };
 
 static bool FlattenXml(IAaptContext* context, xml::XmlResource* xml_res, const StringPiece& path,
-                       bool keep_raw_values, IArchiveWriter* writer) {
+                       bool keep_raw_values, bool utf16, IArchiveWriter* writer) {
   BigBuffer buffer(1024);
   XmlFlattenerOptions options = {};
   options.keep_raw_values = keep_raw_values;
+  options.use_utf16 = utf16;
   XmlFlattener flattener(&buffer, options);
   if (!flattener.Consume(context, xml_res)) {
     return false;
@@ -599,7 +600,7 @@ bool ResourceFileFlattener::Flatten(ResourceTable* table, IArchiveWriter* archiv
               }
             }
             error |= !FlattenXml(context_, doc.get(), dst_path, options_.keep_raw_values,
-                                 archive_writer);
+                                 false /*utf16*/, archive_writer);
           }
         } else {
           error |= !io::CopyFileToArchive(context_, file_op.file_to_copy, file_op.dst_path,
@@ -1383,7 +1384,8 @@ class LinkCommand {
   bool WriteApk(IArchiveWriter* writer, proguard::KeepSet* keep_set, xml::XmlResource* manifest,
                 ResourceTable* table) {
     const bool keep_raw_values = context_->GetPackageType() == PackageType::kStaticLib;
-    bool result = FlattenXml(context_, manifest, "AndroidManifest.xml", keep_raw_values, writer);
+    bool result = FlattenXml(context_, manifest, "AndroidManifest.xml", keep_raw_values,
+                             true /*utf16*/, writer);
     if (!result) {
       return false;
     }

tools/aapt2/flatten/XmlFlattener.cpp

@@ -314,7 +314,11 @@ bool XmlFlattener::Flatten(IAaptContext* context, xml::Node* node) {
   xml_header_writer.StartChunk<ResXMLTree_header>(RES_XML_TYPE);
 
   // Flatten the StringPool.
-  StringPool::FlattenUtf8(buffer_, visitor.pool);
+  if (options_.use_utf16) {
+    StringPool::FlattenUtf16(buffer_, visitor.pool);
+  } else {
+    StringPool::FlattenUtf8(buffer_, visitor.pool);
+  }
 
   {
     // Write the array of resource IDs, indexed by StringPool order.

tools/aapt2/flatten/XmlFlattener.h

@@ -30,6 +30,10 @@ struct XmlFlattenerOptions {
    * Keep attribute raw string values along with typed values.
    */
   bool keep_raw_values = false;
+
+  // Encode the strings in UTF-16. Only needed for AndroidManifest.xml to avoid a bug in
+  // certain non-AOSP platforms: https://issuetracker.google.com/64434571
+  bool use_utf16 = false;
 };
 
 class XmlFlattener : public IXmlResourceConsumer {