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feat: use class fingerprint instead of method fingerprint #164

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3 tasks done
Aunali321 opened this issue Apr 14, 2023 · 3 comments
Open
3 tasks done

feat: use class fingerprint instead of method fingerprint #164

Aunali321 opened this issue Apr 14, 2023 · 3 comments
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Feature request Requesting a new feature that's not implemented yet

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@Aunali321
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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

  • I have searched the existing issues and this is a new and no duplicate or related to another open issue.
  • I have written a short but informative title.
  • I filled out all of the requested information in this issue properly.
@Aunali321 Aunali321 added the Feature request Requesting a new feature that's not implemented yet label Apr 14, 2023
@oSumAtrIX
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Also fields and other metadata like access flags

@badawoll
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badawoll commented May 10, 2023

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
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oSumAtrIX commented May 10, 2023

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.

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Labels
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