Compile and link ioctl on Linux from Swift

main.swift

import Glibc
import CLinuxDVB

@_silgen_name("ioctl") func ioctl(fildes: CInt, request: UInt64, result: UnsafePointer<CInt>) -> Int

print("Compiled against DVB API version \(DVB_API_VERSION).\(DVB_API_VERSION)")

class DVBFrontEnd {
  var fileReference: CInt? = .None
  init?(adapter: Int, number: Int) {
    let path: String = "/dev/dvb/adapter\(adapter)/frontend\(number)"
    fileReference = open(path, O_RDWR | O_NONBLOCK)
    guard fileReference > 0 else {
      fileReference = .None
      return nil
    }
  }

  deinit {
    if let fileReference = self.fileReference {
      close(fileReference)
    }
  }
}

class DVBDVR {
  /// The requested DVR buffer size. The integer represents the number of bytes.
  static let DVR_BUFFER_SIZE: CInt = 40 * 188 * 1024
  var fileReference: CInt? = .None
  init?(adapter: Int, number: Int) {
    let path: String = "/dev/dvb/adapter\(adapter)/dvr\(number)"
    fileReference = open(path, O_RDONLY | O_NONBLOCK)
    guard fileReference > 0 else {
      fileReference = .None
      return nil
    }

    let DMX_SET_BUFFER_SIZE: CUnsignedInt = 28461
    var value = DVBDVR.DVR_BUFFER_SIZE
    let result = ioctl(fileReference!, request: UInt64(DMX_SET_BUFFER_SIZE), result: &value)
    print(result)
  }

  deinit {
    if let fileReference = self.fileReference {
      close(fileReference)
    }
  }
}

print("Would like to set the DVR buffer size to: \(DVBDVR.DVR_BUFFER_SIZE) bytes.")

if let frontend = DVBFrontEnd(adapter: 0, number: 0), let dvr = DVBDVR(adapter: 0, number: 0) {
  print("Connected to the DVB adapters.")
} else {
  print("Could not connect to the DVB adapters.")
}

Package.swift

import PackageDescription

let package = Package(
    name: "CastableLive",
    dependencies: [
        .Package(url: "https://github.com/RLovelett/CLinuxDVB.swift.git", Version(1, 0, 0))
    ]
)

$ swift build
Linking Executable:  .build/debug/CastableLive
/home/ryan/Source/castable-live/.build/debug/CastableLive.o/main.swift.o: In function `_TFC12CastableLive6DVBDVRcfT7adapterSi6numberSi_GSqS0__':
/home/ryan/Source/castable-live/main.swift:40: undefined reference to `ioctl'
/usr/bin/ld: /home/ryan/Source/castable-live/.build/debug/CastableLive: hidden symbol `ioctl' isn't defined
/usr/bin/ld: final link failed: Bad value
clang-3.7: error: linker command failed with exit code 1 (use -v to see invocation)
<unknown>:0: error: link command failed with exit code 1 (use -v to see invocation)
<unknown>:0: error: build had 1 command failures
error: exit(1): ["/usr/bin/swift-build-tool", "-f", "/home/ryan/Source/castable-live/.build/debug/CastableLive.o/llbuild.yaml"]