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[WIP] feat: Add --emit-offsets flag for enhanced reverse engineering (#18) #19

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[WIP] feat: Add --emit-offsets flag for enhanced reverse engineering (#18) #19

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9 changes: 9 additions & 0 deletions .claude/settings.local.json
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
{
"permissions": {
"allow": [
"WebFetch(domain:github.com)"
],
"deny": [],
"ask": []
}
}
148 changes: 137 additions & 11 deletions Sources/swift-section/DumpCommand.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,9 @@ final actor DumpCommand: AsyncParsableCommand {
@Option(name: .shortAndLong, parsing: .upToNextOption, help: "The sections to dump. If not specified, all sections will be dumped.")
var sections: [SwiftSection] = SwiftSection.allCases

@Flag(name: .customLong("emit-offsets"), help: "Enable emitting detailed offset information for data fields, virtual functions, and protocol witnesses.")
var emitOffsets: Bool = false

// @Flag(inversion: .prefixedEnableDisable, help: "Enable searching for metadata.")
private var searchMetadata: Bool = false

Expand All @@ -38,18 +41,20 @@ final actor DumpCommand: AsyncParsableCommand {
func run() async throws {
let machOFile = try MachOFile.load(options: machOOptions)

if searchMetadata {
if searchMetadata || emitOffsets {
metadataFinder = MetadataFinder(machO: machOFile)
}

let demangleOptions = demangleOptions.buildSwiftDumpDemangleOptions()

let shouldEmitOffsets = emitOffsets

for section in sections {
switch section {
case .types:
try await dumpTypes(using: demangleOptions, in: machOFile)
try await dumpTypes(using: demangleOptions, shouldEmitOffsets: shouldEmitOffsets, in: machOFile)
case .protocols:
try await dumpProtocols(using: demangleOptions, in: machOFile)
try await dumpProtocols(using: demangleOptions, shouldEmitOffsets: shouldEmitOffsets, in: machOFile)
case .protocolConformances:
try await dumpProtocolConformances(using: demangleOptions, in: machOFile)
case .associatedTypes:
Expand All @@ -64,7 +69,7 @@ final actor DumpCommand: AsyncParsableCommand {
}

@MainActor
private func dumpTypes(using options: DemangleOptions, in machO: MachOFile) async throws {
private func dumpTypes(using options: DemangleOptions, shouldEmitOffsets: Bool, in machO: MachOFile) async throws {
let typeContextDescriptors = try machO.swift.typeContextDescriptors

for typeContextDescriptor in typeContextDescriptors {
Expand All @@ -80,19 +85,26 @@ final actor DumpCommand: AsyncParsableCommand {
try Struct(descriptor: structDescriptor, in: machO).dump(using: options, in: machO)
}

if let metadata: StructMetadata = try await metadataFinder?.metadata(for: structDescriptor) {
await performDump {
try metadata.fieldOffsets(for: structDescriptor, in: machO)
if shouldEmitOffsets {
if let metadata: StructMetadata = try await metadataFinder?.metadata(for: structDescriptor) {
await performDump {
try await dumpStructFieldOffsets(metadata: metadata, descriptor: structDescriptor, in: machO)
}
}
}
case .class(let classDescriptor):
await performDump {
try Class(descriptor: classDescriptor, in: machO).dump(using: options, in: machO)
}

if let metadata = try await metadataFinder?.metadata(for: classDescriptor) as ClassMetadataObjCInterop? {
await performDump {
try metadata.fieldOffsets(for: classDescriptor, in: machO)
if shouldEmitOffsets {
if let metadata = try await metadataFinder?.metadata(for: classDescriptor) as ClassMetadataObjCInterop? {
await performDump {
try await dumpClassFieldOffsets(metadata: metadata, descriptor: classDescriptor, in: machO)
}
await performDump {
try await dumpClassVTableOffsets(metadata: metadata, classDescriptor: classDescriptor, in: machO)
}
}
}
}
Expand All @@ -113,12 +125,18 @@ final actor DumpCommand: AsyncParsableCommand {
}

@MainActor
private func dumpProtocols(using options: DemangleOptions, in machO: MachOFile) async throws {
private func dumpProtocols(using options: DemangleOptions, shouldEmitOffsets: Bool, in machO: MachOFile) async throws {
let protocolDescriptors = try machO.swift.protocolDescriptors

for protocolDescriptor in protocolDescriptors {
await performDump {
try Protocol(descriptor: protocolDescriptor, in: machO).dump(using: options, in: machO)
}
if shouldEmitOffsets {
await performDump {
try await dumpProtocolWitnessOffsets(descriptor: protocolDescriptor, in: machO)
}
}
}
}

Expand Down Expand Up @@ -162,4 +180,112 @@ final actor DumpCommand: AsyncParsableCommand {
print(string)
}
}

// MARK: - Offset Dumping Methods

private func dumpStructFieldOffsets<MachO: MachORepresentableWithCache & MachOReadable>(
metadata: StructMetadata,
descriptor: StructDescriptor,
in machO: MachO
) async throws -> SemanticString {
let offsets = try metadata.fieldOffsets(for: descriptor, in: machO)
var components: [any SemanticStringComponent] = []

components.append(Comment("Data Field Offsets:"))
for (index, offset) in offsets.enumerated() {
components.append(Comment(" Field \(index): 0x\(String(offset, radix: 16))"))
}

return SemanticString(components: components)
}

private func dumpClassFieldOffsets<MachO: MachORepresentableWithCache & MachOReadable>(
metadata: ClassMetadataObjCInterop,
descriptor: ClassDescriptor,
in machO: MachO
) async throws -> SemanticString {
let offsets = try metadata.fieldOffsets(for: descriptor, in: machO)
var components: [any SemanticStringComponent] = []

components.append(Comment("Data Field Offsets:"))
for (index, offset) in offsets.enumerated() {
components.append(Comment(" Field \(index): 0x\(String(offset, radix: 16))"))
}

return SemanticString(components: components)
}

private func dumpClassVTableOffsets<MachO: MachORepresentableWithCache & MachOReadable>(
metadata: ClassMetadataObjCInterop,
classDescriptor: ClassDescriptor,
in machO: MachO
) async throws -> SemanticString {
var components: [any SemanticStringComponent] = []

components.append(Comment("Virtual Function Offsets:"))

// Create Class object to access vtable information
do {
let classType = try Class(descriptor: classDescriptor, in: machO)
if let vTableDescriptorHeader = classType.vTableDescriptorHeader {
let vTableOffset = vTableDescriptorHeader.layout.vTableOffset
let vTableSize = vTableDescriptorHeader.layout.vTableSize

components.append(Comment(" VTable Offset: 0x\(String(vTableOffset, radix: 16))"))
components.append(Comment(" VTable Size: \(vTableSize) entries"))

// Calculate individual method offsets
for i in 0..<vTableSize {
let methodOffset = vTableOffset + (i * UInt32(MemoryLayout<UInt64>.size))
components.append(Comment(" Method \(i): 0x\(String(methodOffset, radix: 16))"))
}
} else {
components.append(Comment(" VTable information not available"))
}
} catch {
components.append(Comment(" Error accessing class information: \(error.localizedDescription)"))
}

return SemanticString(components: components)
}

private func dumpProtocolWitnessOffsets(
descriptor: ProtocolDescriptor,
in machO: MachOFile
) async throws -> SemanticString {
var components: [any SemanticStringComponent] = []

components.append(Comment("Protocol Witness Offsets:"))

// Look for protocol conformances that implement this protocol
let protocolConformanceDescriptors = try machO.swift.protocolConformanceDescriptors
let relatedConformances = protocolConformanceDescriptors.compactMap { conformance -> ProtocolConformanceDescriptor? in
// Check if this conformance is for our protocol
do {
if let protocolSymbol = try conformance.protocolDescriptor(in: machO),
let conformanceProtocol = protocolSymbol.resolved {
return conformanceProtocol.offset == descriptor.offset ? conformance : nil
} else {
return nil
}
} catch {
return nil
}
}

if relatedConformances.isEmpty {
components.append(Comment(" No conformances found"))
} else {
for (index, conformance) in relatedConformances.enumerated() {
components.append(Comment(" Conformance \(index): 0x\(String(conformance.offset, radix: 16))"))

// Try to get witness table information
if let witnessTablePattern = try? conformance.witnessTablePattern(in: machO) {
components.append(Comment(" Witness Table: 0x\(String(witnessTablePattern.offset, radix: 16))"))
}
}
}

return SemanticString(components: components)
}
}