Merge pull request #80 from p-x9/feature/external-relocation

External relocation infos
p-x9 · May 13, 2024 · d356902 · d356902
2 parents 934929b + 5fcf566
commit d356902
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diff --git a/Sources/MachOKit/MachOFile.swift b/Sources/MachOKit/MachOFile.swift
@@ -401,6 +401,27 @@ extension MachOFile {
     }
 }
 
+extension MachOFile {
+    public var externalRelocations: DataSequence<Relocation>? {
+        guard let dysymtab = loadCommands.dysymtab else {
+            return nil
+        }
+        return fileHandle.readDataSequence(
+            offset: numericCast(dysymtab.extreloff),
+            numberOfElements: numericCast(dysymtab.nextrel),
+            swapHandler: { data in
+                guard self.isSwapped else { return }
+                data.withUnsafeMutableBytes {
+                    guard let baseAddress = $0.baseAddress else { return }
+                    let ptr = baseAddress
+                        .assumingMemoryBound(to: relocation_info.self)
+                    swap_relocation_info(ptr, dysymtab.nextrel, NXHostByteOrder())
+                }
+            }
+        )
+    }
+}
+
 extension MachOFile {
     public var isEncrypted: Bool {
         if let encryptionInfo = loadCommands.encryptionInfo {

diff --git a/Sources/MachOKit/MachOImage.swift b/Sources/MachOKit/MachOImage.swift
@@ -582,6 +582,28 @@ extension MachOImage {
     }
 }
 
+extension MachOImage {
+    public var externalRelocations: MemorySequence<Relocation>? {
+        guard let dysymtab = loadCommands.dysymtab else { return nil }
+
+        let linkedit: (any SegmentCommandProtocol)? = loadCommands.linkedit64 ?? loadCommands.linkedit
+
+        guard let linkedit,
+              let vmaddrSlide,
+              let start = linkedit.startPtr(vmaddrSlide: vmaddrSlide) else {
+            return nil
+        }
+
+        return .init(
+            basePointer: start
+                .advanced(by: -linkedit.fileOffset)
+                .advanced(by: numericCast(dysymtab.extreloff))
+                .assumingMemoryBound(to: Relocation.self),
+            numberOfElements: numericCast(dysymtab.nextrel)
+        )
+    }
+}
+
 extension MachOImage {
     public var codeSign: CodeSign? {
         guard let vmaddrSlide,

diff --git a/Sources/MachOKit/Protocol/MachORepresentable.swift b/Sources/MachOKit/Protocol/MachORepresentable.swift
@@ -21,6 +21,7 @@ public protocol MachORepresentable {
     associatedtype FunctionStarts: Sequence<FunctionStart>
     associatedtype DataInCode: RandomAccessCollection<DataInCodeEntry>
     associatedtype DyldChainedFixups: DyldChainedFixupsProtocol
+    associatedtype ExternalRelocations: RandomAccessCollection<Relocation>
     associatedtype CodeSign: CodeSignProtocol
 
     /// A boolean value that indicates whether MachO is a 64-bit architecture.
@@ -133,6 +134,9 @@ public protocol MachORepresentable {
 
     /// Chained fixup infos
     var dyldChainedFixups: DyldChainedFixups? { get }
+
+    /// Sequence of external relocation infos
+    var externalRelocations: ExternalRelocations? { get }
 
     /// Code sign infos
     var codeSign: CodeSign? { get }

diff --git a/Tests/MachOKitTests/MachOFilePrintTests.swift b/Tests/MachOKitTests/MachOFilePrintTests.swift
@@ -144,6 +144,49 @@ final class MachOFilePrintTests: XCTestCase {
         }
     }
 
+    func testExternalRelocations() {
+        guard let relocations = machO.externalRelocations else {
+            return
+        }
+        let symbols = machO.symbols
+        for relocation in relocations {
+            print("--")
+            switch relocation.info {
+            case let .general(info):
+                print("Offset:", "0x" + String(info.r_address, radix: 16))
+                if let length = info.length {
+                    print("Length:", length)
+                }
+                print("isExternal:", info.isExternal)
+                print("isScatted:", info.isScattered)
+                print("pcRelative:", info.isRelocatedPCRelative)
+                if let symbolIndex = info.symbolIndex {
+                    print("SymbolIndex:", symbolIndex)
+                    print("SymbolName:", symbols[AnyIndex(symbolIndex)].name)
+                }
+                if let sectionOrdinal = info.sectionOrdinal {
+                    print("SectionOrdinal:", sectionOrdinal)
+                }
+                if let cpuType = machO.header.cpuType,
+                   let type = info.type(for: cpuType) {
+                    print("Type:", type)
+                }
+            case let .scattered(info):
+                print("Offset:", "0x" + String(info.layout.r_address, radix: 16))
+                if let length = info.length {
+                    print("Length:", length)
+                }
+                print("isScatted:", info.isScattered)
+                print("pcRelative:", info.isRelocatedPCRelative)
+                if let cpuType = machO.header.cpuType,
+                   let type = info.type(for: cpuType) {
+                    print("Type:", type)
+                }
+                print("Value:", "0x" + String(info.r_value, radix: 16))
+            }
+        }
+    }
+
     func testDependencies() throws {
         for dependency in machO.dependencies {
             let dependency = dependency.dylib

diff --git a/Tests/MachOKitTests/MachOPrintTests.swift b/Tests/MachOKitTests/MachOPrintTests.swift
@@ -73,6 +73,49 @@ final class MachOPrintTests: XCTestCase {
         }
     }
 
+    func testExternalRelocations() {
+        guard let relocations = machO.externalRelocations else {
+            return
+        }
+        let symbols = machO.symbols
+        for relocation in relocations {
+            print("--")
+            switch relocation.info {
+            case let .general(info):
+                print("Offset:", "0x" + String(info.r_address, radix: 16))
+                if let length = info.length {
+                    print("Length:", length)
+                }
+                print("isExternal:", info.isExternal)
+                print("isScatted:", info.isScattered)
+                print("pcRelative:", info.isRelocatedPCRelative)
+                if let symbolIndex = info.symbolIndex {
+                    print("SymbolIndex:", symbolIndex)
+                    print("SymbolName:", symbols[AnyIndex(symbolIndex)].name)
+                }
+                if let sectionOrdinal = info.sectionOrdinal {
+                    print("SectionOrdinal:", sectionOrdinal)
+                }
+                if let cpuType = machO.header.cpuType,
+                   let type = info.type(for: cpuType) {
+                    print("Type:", type)
+                }
+            case let .scattered(info):
+                print("Offset:", "0x" + String(info.layout.r_address, radix: 16))
+                if let length = info.length {
+                    print("Length:", length)
+                }
+                print("isScatted:", info.isScattered)
+                print("pcRelative:", info.isRelocatedPCRelative)
+                if let cpuType = machO.header.cpuType,
+                   let type = info.type(for: cpuType) {
+                    print("Type:", type)
+                }
+                print("Value:", "0x" + String(info.r_value, radix: 16))
+            }
+        }
+    }
+
     func testDependencies() throws {
         for dependency in machO.dependencies {
             let dependency = dependency.dylib