Swift demangler

demangler.swift

import Foundation

guard CommandLine.arguments.count > 1 else {
  print("Please specify object file/executable")
  exit(EXIT_FAILURE)
}

var nm = Process()
nm.launchPath = "/usr/bin/nm"
nm.arguments = [CommandLine.arguments[1]]
let pipe = Pipe()
nm.standardOutput = pipe.fileHandleForWriting
nm.launch()

pipe.fileHandleForWriting.closeFile()
let output = String(data: pipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8)!

for line in output.components(separatedBy: "\n").dropLast() {
  var line = line
  if let symstart = line.lastIndex(of: " ") {
    let symrange = line.index(symstart, offsetBy: 1) ..< line.endIndex
    if let demangled = demangle(symbol: String(line[symrange])) {
      line += " ==> " + demangled
    }
  }
  print(line)
}

nm.waitUntilExit()

func demangle(symbol: String) -> String? {
  return symbol.withCString { cString -> String? in
    if let demangled = _stdlib_demangleImpl(cString,
      mangledNameLength: UInt(strlen(cString)),
      outputBuffer: nil, outputBufferSize: nil, flags: 0) ??
    __cxa_demangle(cString+1, output_buffer: nil,
      length: nil, status: nil) {
        let out = String(cString: demangled)
        free(demangled)
        return out
      }
    return nil
  }
}

@_silgen_name("swift_demangle")
privatefunc _stdlib_demangleImpl(_ mangledName: UnsafePointer<Int8>?, mangledNameLength: UInt, outputBuffer: UnsafeMutablePointer<Int8>?, outputBufferSize: UnsafeMutablePointer<UInt>?, flags: UInt32) -> UnsafeMutablePointer<Int8>?

@_silgen_name("__cxa_demangle")
func __cxa_demangle(_ mangled_name: UnsafePointer<Int8>?, output_buffer: UnsafePointer<Int8>?, length: UnsafeMutablePointer<size_t>?, status: UnsafeMutablePointer<Int32>?) -> UnsafeMutablePointer<Int8>?