WebViewDataTest fails on API 26+ after Android Profiler file injection (part 1: whitelist)

[mcomella]

Stack trace:

java.lang.AssertionError: Expected file 'perfd' to be in the app's data dir whitelist
at org.junit.Assert.fail(Assert.java:88)
at org.junit.Assert.assertTrue(Assert.java:41)
at org.mozilla.focus.activity.WebViewDataTest.DeleteWebViewDataTest(WebViewDataTest.java:205)
at java.lang.reflect.Method.invoke(Native Method)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

It seems there are a few files in the data/ directory that don't exist on my API 23 emulator, which is why I didn't catch this sooner.

We should also verify that these files, if we whitelist them, aren't leaking browsing state. Otherwise, we should delete them!

[mcomella]

These may come from the new Android Studio 3.0 profiler. Three files I noticed are:

• perfa.jar
• perfd (binary file)
• libperfa_x86.so

The contents of perfa.jar:

$ unzip perfa.jar
Archive:  perfa.jar
  inflating: META-INF/MANIFEST.MF
  inflating: classes.dex
   creating: com/
   creating: com/android/
   creating: com/android/tools/
   creating: com/android/tools/profiler/
   creating: com/android/tools/profiler/support/
   creating: com/android/tools/profiler/support/event/
   creating: com/android/tools/profiler/support/memory/
   creating: com/android/tools/profiler/support/network/
   creating: com/android/tools/profiler/support/network/httpurl/
   creating: com/android/tools/profiler/support/network/okhttp/
   creating: com/android/tools/profiler/support/network/okhttp/reflection/
   creating: com/android/tools/profiler/support/network/okhttp/reflection/okhttp2/
   creating: com/android/tools/profiler/support/network/okhttp/reflection/okhttp3/
   creating: com/android/tools/profiler/support/network/okhttp/reflection/okio/
   creating: com/android/tools/profiler/support/profilers/
   creating: com/android/tools/profiler/support/util/

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I confirmed that these files are not injected in AS 2.3.3 but are in 3.0.1.

The new profiler description page mentions, "To show you advanced profiling data, Android Studio must inject monitoring logic into your compiled app." After following the directions to enable it, I see:

Which leads me to the conclusion: Android Studio 3.0+ is automatically injecting profiler related files on API 26+ and this can also be enabled for APIs below 26: I assume this only affects debug builds. Note that I did not extensively test this so this conclusion may be wrong in some cases.

[mcomella]

We should also verify that these files, if we whitelist them, aren't leaking browsing state. Otherwise, we should delete them!

I don't want to delete them because this may break our ability to correctly profile the app so I'm going to whitelist them.

[mcomella]

I'm having second thoughts – if our intent is to ensure there is no browsing data left on disk and the profiler caches browsing data on disk, shouldn't we delete the profiler's files? I'm going to investigate if these files are added in:

1. Release builds
2. Gradle-only builds (i.e. not from Android Studio)

If so:

• We should delete the profiler's files on clean-up
• To prevent the profiler from breaking, in local builds we can have a branch to avoid deleting those files

If not:

• The simple solution is to whitelist the files. It could be insecure if these files are added to release builds later
• We could delete on cleanup and add a branch that doesn't delete the profile, as per the above.

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fwiw, perfd contained "localhost" (or, at least the binary data in the file matched "localhost") and broke the test even when I whitelist the files; perhaps this is not surprising because it has a network monitor.

[mcomella]

It appears data these profiler files will only be injected if you build via Android Studio and you have opened the "Android profiler" tab at least once since this current Android Studio process has been launched.

I think we should whitelist these so we don't break local builds and I think it's unlikely that these files will be added for release builds so it should be safe.