Convert integers to char literals

Some character literals are treated as integers by Fernflower, as the
complement operator always evaluates to an integer, even if its operand
is a character. This is fine, but ComplementTransformer removes some
complement transformers - leaving integer literals where Fernflower
would normally insert a character literal.

This transformer converts complemented integers to char literals in some
cases where it makes sense (it is difficult to perform this
transformation across every type of expression in JavaParser).

Signed-off-by: Graham <gpe@openrs2.dev>
Graham 4 years ago
parent 12a0f17e59
commit 68b2f67522
  1. 2
      deob-ast/src/main/java/dev/openrs2/deob/ast/AstDeobfuscatorModule.kt
  2. 86
      deob-ast/src/main/java/dev/openrs2/deob/ast/transform/CharLiteralTransformer.kt

@ -8,6 +8,7 @@ import dev.openrs2.deob.ast.gl.GlRegistryProvider
import dev.openrs2.deob.ast.transform.AddSubTransformer
import dev.openrs2.deob.ast.transform.BinaryExprOrderTransformer
import dev.openrs2.deob.ast.transform.BitMaskTransformer
import dev.openrs2.deob.ast.transform.CharLiteralTransformer
import dev.openrs2.deob.ast.transform.ComplementTransformer
import dev.openrs2.deob.ast.transform.EncloseTransformer
import dev.openrs2.deob.ast.transform.ForLoopConditionTransformer
@ -33,6 +34,7 @@ object AstDeobfuscatorModule : AbstractModule() {
binder.addBinding().to(UnencloseTransformer::class.java)
binder.addBinding().to(NegativeLiteralTransformer::class.java)
binder.addBinding().to(ComplementTransformer::class.java)
binder.addBinding().to(CharLiteralTransformer::class.java)
binder.addBinding().to(IfElseTransformer::class.java)
binder.addBinding().to(TernaryTransformer::class.java)
binder.addBinding().to(BinaryExprOrderTransformer::class.java)

@ -0,0 +1,86 @@
package dev.openrs2.deob.ast.transform
import com.github.javaparser.ast.CompilationUnit
import com.github.javaparser.ast.expr.AssignExpr
import com.github.javaparser.ast.expr.BinaryExpr
import com.github.javaparser.ast.expr.BinaryExpr.Operator.EQUALS
import com.github.javaparser.ast.expr.BinaryExpr.Operator.GREATER
import com.github.javaparser.ast.expr.BinaryExpr.Operator.GREATER_EQUALS
import com.github.javaparser.ast.expr.BinaryExpr.Operator.LESS
import com.github.javaparser.ast.expr.BinaryExpr.Operator.LESS_EQUALS
import com.github.javaparser.ast.expr.BinaryExpr.Operator.MINUS
import com.github.javaparser.ast.expr.BinaryExpr.Operator.NOT_EQUALS
import com.github.javaparser.ast.expr.BinaryExpr.Operator.PLUS
import com.github.javaparser.ast.expr.CharLiteralExpr
import com.github.javaparser.ast.expr.Expression
import com.github.javaparser.ast.expr.IntegerLiteralExpr
import com.github.javaparser.resolution.types.ResolvedPrimitiveType
import dev.openrs2.deob.ast.Library
import dev.openrs2.deob.ast.LibraryGroup
import dev.openrs2.deob.ast.util.walk
import java.lang.Character.CONTROL
import java.lang.Character.FORMAT
import java.lang.Character.LINE_SEPARATOR
import java.lang.Character.PARAGRAPH_SEPARATOR
import java.lang.Character.PRIVATE_USE
import java.lang.Character.SURROGATE
import java.lang.Character.UNASSIGNED
class CharLiteralTransformer : Transformer() {
override fun transformUnit(group: LibraryGroup, library: Library, unit: CompilationUnit) {
unit.walk { expr: BinaryExpr ->
if (expr.operator in COMPARISON_OPERATORS || expr.operator == PLUS || expr.operator == MINUS) {
convertToCharLiteral(expr.left, expr.right)
convertToCharLiteral(expr.right, expr.left)
}
}
unit.walk { expr: AssignExpr ->
convertToCharLiteral(expr.target, expr.value)
}
}
private fun convertToCharLiteral(a: Expression, b: Expression) {
if (a.calculateResolvedType() != ResolvedPrimitiveType.CHAR) {
return
} else if (b !is IntegerLiteralExpr) {
return
}
b.replace(CharLiteralExpr(escape(b.asNumber().toChar())))
}
private fun escape(c: Char): String {
// compatible with Fernflower's character escape code
return when (c) {
'\b' -> "\\b"
'\t' -> "\\t"
'\n' -> "\\n"
'\u000c' -> "\\f"
'r' -> "\\r"
'\'' -> "'"
'\\' -> "\\"
else -> {
val type = Character.getType(c).toByte()
if (type in UNPRINTABLE_TYPES) {
"\\u" + Integer.toHexString(c.toInt()).padStart(4, '0')
} else {
c.toString()
}
}
}
}
private companion object {
private val COMPARISON_OPERATORS = setOf(EQUALS, NOT_EQUALS, LESS, GREATER, LESS_EQUALS, GREATER_EQUALS)
private val UNPRINTABLE_TYPES = setOf(
UNASSIGNED,
LINE_SEPARATOR,
PARAGRAPH_SEPARATOR,
CONTROL,
FORMAT,
PRIVATE_USE,
SURROGATE
)
}
}
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