Reads a Mach-O header

readMachOHeader.swift

import Foundation
import MachO.dyld

func readMachOHeader(path: String) {
    guard let data = try? Data(contentsOf: URL(fileURLWithPath: path)) else {
        print("Failed to read file")
        return
    }

    data.withUnsafeBytes { rawBufferPointer in
        guard let baseAddress = rawBufferPointer.baseAddress else {
            print("Failed to get base address")
            return
        }

        let header = baseAddress.assumingMemoryBound(to: mach_header_64.self).pointee
        if header.magic == MH_MAGIC_64 {
            printHeader64Info(data: data)
        } else {
            print("Not a valid 64-bit Mach-O file.")
        }
    }
}

func printHeader64Info(data: Data) {
    data.withUnsafeBytes { (rawBufferPointer: UnsafeRawBufferPointer) in
        guard let header = rawBufferPointer.bindMemory(to: mach_header_64.self).baseAddress?.pointee else {
            print("Failed to read header")
            return
        }

        print("Mach-O Header Information:")
        print("Magic: 0x\(String(format: "%X", header.magic))")
        print("CPU Type: \(header.cputype)")
        print("CPU Subtype: \(header.cpusubtype)")
        print("File Type: \(header.filetype)")
        print("Number of Load Commands: \(header.ncmds)")
        print("Size of Load Commands: \(header.sizeofcmds)")
        print("Flags: 0x\(String(format: "%X", header.flags))")

        let headerSize = MemoryLayout<mach_header_64>.size
        var offset = headerSize

        for _ in 0..<header.ncmds {
            let loadCmd = rawBufferPointer.loadUnaligned(fromByteOffset: offset, as: load_command.self)

            print("\nLoad Command:")
            print("  Type: \(loadCmd.cmd)")
            print("  Size: \(loadCmd.cmdsize)")

            if loadCmd.cmd == LC_SEGMENT_64 {
                let segmentCmd = rawBufferPointer.loadUnaligned(fromByteOffset: offset, as: segment_command_64.self)

                let segmentName = withUnsafeBytes(of: segmentCmd.segname) { bytes in
                    String(bytes: bytes.prefix(while: { $0 != 0 }), encoding: .ascii) ?? ""
                }

                print("  Segment Name: \(segmentName)")
                print("  VM Address: 0x\(String(format: "%llX", segmentCmd.vmaddr))")
                print("  VM Size: \(segmentCmd.vmsize)")
                print("  File Offset: \(segmentCmd.fileoff)")
                print("  File Size: \(segmentCmd.filesize)")
            }

            offset += Int(loadCmd.cmdsize)
        }
    }
}

let path = "/Users/jano/Desktop/Hello/UseHello"
readMachOHeader(path: path)