Resource Path Obfuscation

This CL allows aapt2 to obfuscate resource paths within the output apk
and move resources to shorter obfuscated paths. This reduces apk size
when there is a large number of resources since the path metadata exists
in 4 places in the apk.

This CL adds two arguments to aapt2, one to enable resource path
obfuscation and one to point to a path to output the path map to (for
later debugging).

Test: make aapt2_tests
Bug: b/75965637

Change-Id: I9cacafe1d17800d673566b2d61b0b88f3fb8d60c

1 files changed, 12 insertions, 2 deletions

diff --git a/tools/aapt2/LoadedApk.cpp b/tools/aapt2/LoadedApk.cpp
index b353ff00a23f..45719ef474cd 100644
--- a/tools/aapt2/LoadedApk.cpp
+++ b/tools/aapt2/LoadedApk.cpp
@@ -223,8 +223,17 @@ bool LoadedApk::WriteToArchive(IAaptContext* context, ResourceTable* split_table
     io::IFile* file = iterator->Next();
     std::string path = file->GetSource().path;
 
+    std::string output_path = path;
+    bool is_resource = path.find("res/") == 0;
+    if (is_resource) {
+      auto it = options.shortened_path_map.find(path);
+      if (it != options.shortened_path_map.end()) {
+        output_path = it->second;
+      }
+    }
+
     // Skip resources that are not referenced if requested.
-    if (path.find("res/") == 0 && referenced_resources.find(path) == referenced_resources.end()) {
+    if (is_resource && referenced_resources.find(output_path) == referenced_resources.end()) {
       if (context->IsVerbose()) {
         context->GetDiagnostics()->Note(DiagMessage()
                                         << "Removing resource '" << path << "' from APK.");
@@ -283,7 +292,8 @@ bool LoadedApk::WriteToArchive(IAaptContext* context, ResourceTable* split_table
         return false;
       }
     } else {
-      if (!io::CopyFileToArchivePreserveCompression(context, file, path, writer)) {
+      if (!io::CopyFileToArchivePreserveCompression(
+              context, file, output_path, writer)) {
         return false;
       }
     }