[core] UnsupportedOperationException in addResourceFields

[adithya2306]

Adding R class fields names to java code fails when decompiling a system apk from Android 13 (API 33).
Occurs in latest stable version (1.4.3) as well as nightly (1.4.3.63-127f0ecf).

$ jadx SystemUIGoogle.apk
INFO  - loading ...
ERROR - Failed to parse '.arsc' file
java.lang.UnsupportedOperationException: null
        at java.base/java.util.AbstractList.add(AbstractList.java:153)
        at java.base/java.util.AbstractList.add(AbstractList.java:111)
        at jadx.core.utils.android.AndroidResourcesUtils.lambda$addResourceFields$2(AndroidResourcesUtils.java:132)
        at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1134)
        at jadx.core.utils.android.AndroidResourcesUtils.addResourceFields(AndroidResourcesUtils.java:126)
        at jadx.core.utils.android.AndroidResourcesUtils.searchAppResClass(AndroidResourcesUtils.java:52)
        at jadx.core.dex.nodes.RootNode.processResources(RootNode.java:195)
        at jadx.core.dex.nodes.RootNode.loadResources(RootNode.java:175)
        at jadx.api.JadxDecompiler.load(JadxDecompiler.java:122)
        at jadx.cli.JadxCLI.processAndSave(JadxCLI.java:48)
        at jadx.cli.JadxCLI.execute(JadxCLI.java:36)
        at jadx.cli.JadxCLI.main(JadxCLI.java:20)
INFO  - processing ...
ERROR - finished with errors, count: 7 
$ jadx --version
1.4.3.63-127f0ecf
$ java --version
openjdk 11.0.16 2022-07-19
OpenJDK Runtime Environment (build 11.0.16+8-post-Ubuntu-0ubuntu122.04)
OpenJDK 64-Bit Server VM (build 11.0.16+8-post-Ubuntu-0ubuntu122.04, mixed mode, sharing)

Link to the apk: https://dumps.tadiphone.dev/dumps/google/generic/-/raw/redfin-user-13-TP1A.220624.014-8819323-release-keys/system_ext/priv-app/SystemUIGoogle/SystemUIGoogle.apk

[jpstotz]

The problem is that ClassNode.fields is initialized using fieldsConsumer.getResult() which can return an Collections.emptyList() which does not allow adding fields.

Changing the call in AndoridresourceUtils.addResourceFields from typeCls.getFields().add(newResField); to typeCls.addField(newResField); would be the first step and then changing ClassNode.addField to first check if the current field list is the empty singleton the second.

The question that I can not answer is: At the moment the ClassNode.fields is identical to the fieldsConsumer list, that means adding an entry to the fields list also adds it to the fieldConsumer. Is this necessary/required or can we simply assign a new list to ClassNode.fields?

I have implemented the mentioned changes here: jpstotz@fdd647d

[skylot]

@jpstotz thanks for check and fix!

or can we simply assign a new list to ClassNode.fields

Sure, fieldsConsumer is a temporary object for holding results and should be GC after initial load.

Side note: I don't like using list getter for adding item, I wish java have ImmutableList interface 🙂
And in addition, I even have a weird set of methods like safeAdd to handle adding into empty immutable list. So you may found code like this: 🤣

cls.setDependencies(ListUtils.safeAdd(cls.getDependencies(), outerCls.getTopParentClass()));

[jpstotz]

@skylot The PR is ready that fixes this issue. But while testing the linked APK file I noticed that it causes an StackOverflowError in jadx.api.JavaClass.getTopParentClass (happens automatically when you decompile the code).

[skylot]

@jpstotz thank you 👍

it causes an StackOverflowError in jadx.api.JavaClass.getTopParentClass

I commit a fix for this 🙂