Add a GetMappedPackageLength to Updater

Corresponds to GetMappedPackageAddress.

There is at least one custom device recovery with an extension to copy
the package somewhere else as a backup. Ability to do this was removed
in change ag/955273.

Test: lunch cf_x86_tv-eng; make
Test: atest recovery_unit_test recovery_component_test
Change-Id: I0e61d8a8839c47721874526504ea03b9ca7bafa9
diff --git a/edify/include/edify/updater_interface.h b/edify/include/edify/updater_interface.h
index a4d581e..aa977e3 100644
--- a/edify/include/edify/updater_interface.h
+++ b/edify/include/edify/updater_interface.h
@@ -44,4 +44,5 @@
   virtual ZipArchiveHandle GetPackageHandle() const = 0;
   virtual std::string GetResult() const = 0;
   virtual uint8_t* GetMappedPackageAddress() const = 0;
+  virtual size_t GetMappedPackageLength() const = 0;
 };
diff --git a/updater/include/updater/updater.h b/updater/include/updater/updater.h
index 08816bf..8676b60 100644
--- a/updater/include/updater/updater.h
+++ b/updater/include/updater/updater.h
@@ -62,10 +62,12 @@
   std::string GetResult() const override {
     return result_;
   }
-
   uint8_t* GetMappedPackageAddress() const override {
     return mapped_package_.addr;
   }
+  size_t GetMappedPackageLength() const override {
+    return mapped_package_.length;
+  }
 
  private:
   friend class UpdaterTestBase;