feat: use class fingerprint instead of method fingerprint

[Aunali321]

Type

Functionality

Issue

Class fingerprints are helpful to find methods that have same method signature.

Feature

object MyClassFingerprint : ClassFingerprint(
    "com/example/package/MyClass",  // Name of the class
    listOf( // list of method signatures present in the class
        MethodFingerprint("V", AccessFlags.PUBLIC or AccessFlags.FINAL, listOf("L", "L", "L"), listOf(
            // Opcode list for method 1
        )),

        MethodFingerprint(strings = listOf("force_overlay", "Media#updateFields", "live_reels_metadata"))

        MethodFingerprint(customFingerprint = { methodDef ->
            methodDef.definingClass.endsWith("ClipsEditMetadataController;")
    }),

        // Add more method fingerprints as needed
    ),
    // Number of methods in the class
    3
)

ClassFingerprint: This is a class that extends the Fingerprint class and is used to define the fingerprint of the target class. The ClassFingerprint includes a set of characteristics that uniquely identify the target class, such as the class name, method signatures, and number of methods in the class.

Other details are self-explanatory.

Motivation

1. Class structure is more stable
2. More precise matching
3. Less prone to false positives

Additional context

No response

Acknowledgements

• [X] I have searched the existing issues and this is a new and no duplicate or related to another open issue.
• [X] I have written a short but informative title.
• [X] I filled out all of the requested information in this issue properly.

[oSumAtrIX]

Also fields and other metadata like access flags

[badawoll]

This feature came up in a discussion here.

Not sure what the best way to implement this would be (I don't have much Kotlin development experience), I came up with two viable solutions (they both expose ClassDef to `customFingerprint):

• change customFingerprint signature to (Method, ClassDef) -> Bool. It's clean (nice API), but breaks pretty much all patches that depend on a custom fingerprint.
• create a MethodProxy class that implements Method, but also accepts a ClassDef as a constructor argument, and makes it publicly accessible. Doesn't break API, but feels more hacky.

Maybe there exists even a cleaner way? I looked at extensions, but I couldn't find a nice way to pass a local variable into an extension function/field.

MethodFingerprint could also be reworked to perform matching on the ClassDef.

[oSumAtrIX]

The first way is not an issue. The commit will be marked as a breaking change, if patches update to it, they will have to adjust.