Placeholder API for encrypted storage

Add a method to retrieve the path to encrypted storage. For now,
always return null, as there isn't any.

Bug: 254454578
Bug: 243512108
Test: atest MicrodroidTests
Change-Id: I87868e878dcbc0f2d13870024efbaafb0b52d7e3
diff --git a/tests/testapk/src/java/com/android/microdroid/test/MicrodroidTests.java b/tests/testapk/src/java/com/android/microdroid/test/MicrodroidTests.java
index c7321d5..da7c7ec 100644
--- a/tests/testapk/src/java/com/android/microdroid/test/MicrodroidTests.java
+++ b/tests/testapk/src/java/com/android/microdroid/test/MicrodroidTests.java
@@ -121,6 +121,7 @@
         assertThat(testResults.mAppRunProp).isEqualTo("true");
         assertThat(testResults.mSublibRunProp).isEqualTo("true");
         assertThat(testResults.mApkContentsPath).isEqualTo("/mnt/apk");
+        assertThat(testResults.mEncryptedStoragePath).isEqualTo("");
     }
 
     @Test
@@ -707,6 +708,7 @@
         String mSublibRunProp;
         String mExtraApkTestProp;
         String mApkContentsPath;
+        String mEncryptedStoragePath;
     }
 
     private TestResults runVmTestService(VirtualMachine vm) throws Exception {
@@ -728,6 +730,8 @@
                             testResults.mExtraApkTestProp =
                                     testService.readProperty("debug.microdroid.test.extra_apk");
                             testResults.mApkContentsPath = testService.getApkContentsPath();
+                            testResults.mEncryptedStoragePath =
+                                    testService.getEncryptedStoragePath();
                         } catch (Exception e) {
                             testResults.mException = e;
                         }
diff --git a/tests/testapk/src/native/testbinary.cpp b/tests/testapk/src/native/testbinary.cpp
index 48942dc..694f452 100644
--- a/tests/testapk/src/native/testbinary.cpp
+++ b/tests/testapk/src/native/testbinary.cpp
@@ -123,6 +123,16 @@
             *out = path;
             return ndk::ScopedAStatus::ok();
         }
+
+        ndk::ScopedAStatus getEncryptedStoragePath(std::string* out) override {
+            const char* path_c = AVmPayload_getEncryptedStoragePath();
+            if (path_c == nullptr) {
+                out->clear();
+            } else {
+                *out = path_c;
+            }
+            return ndk::ScopedAStatus::ok();
+        }
     };
     auto testService = ndk::SharedRefBase::make<TestService>();