swift - 如何调用IOCFPlugInInterface.QueryInterface()查询USB设备

Question

我想将此 USB 检测器转换为 Swift 3 https://gist.github.com/zachbadgett/471d72e83fee413d0f38

但是我卡在了这条线上:

let deviceInterfaceResult = plugInInterface.QueryInterface(
        plugInInterfacePtrPtr,
        CFUUIDGetUUIDBytes(kIOUSBDeviceInterfaceID),
&deviceInterfaceVoidPtr)

Cannot call value of non-function type '(@convention(c) (UnsafeMutableRawPointer?, REFIID, UnsafeMutablePointer?) -> HRESULT)!'

来源查询接口(interface):

public var QueryInterface: (@convention(c) (UnsafeMutableRawPointer?, REFIID, UnsafeMutablePointer<LPVOID?>?) -> HRESULT)!

如何调用这个函数？ Using CFNotificationCallback in Swift, or, @convention(c) blocks in Swift这个答案对我没有帮助。

Answer 1

Cœur 的答案非常接近。 plugInInterface.QueryInterface()期望作为最后一个参数的是 double-indirect pointer

的地址

UnsafeMutablePointer<UnsafeMutablePointer<IOUSBDeviceInterface>?>?

但“伪装”为指向 LPVOID? 的指针又名 UnsafeMutableRawPointer .因此，获得的指针必须被取消引用两次。 withMemoryRebound()可用于此指针转换。

我对代码做了一些修改:

• 使用defer继续使用下一个 USB 设备，即使由于错误，当前迭代被“中止”。
• 删除不必要的类型注释。
• 使用MemoryLayout<io_name_t>.size而不是 128 .
• 发布 usbDevice以及使用后的接口(interface)指针，以避免内存泄漏。
• 将一些变量声明从顶部移到需要的地方。

综合起来:

import Foundation
import IOKit
import IOKit.usb
import IOKit.usb.IOUSBLib

print("Scanning USB Bus.....\n\n\n")

//
// These constants are not imported into Swift from IOUSBLib.h as they
// are all #define constants
//

let kIOUSBDeviceUserClientTypeID = CFUUIDGetConstantUUIDWithBytes(kCFAllocatorDefault,
                                                                  0x9d, 0xc7, 0xb7, 0x80, 0x9e, 0xc0, 0x11, 0xD4,
                                                                  0xa5, 0x4f, 0x00, 0x0a, 0x27, 0x05, 0x28, 0x61)

let kIOCFPlugInInterfaceID = CFUUIDGetConstantUUIDWithBytes(kCFAllocatorDefault,
                                                            0xC2, 0x44, 0xE8, 0x58, 0x10, 0x9C, 0x11, 0xD4,
                                                            0x91, 0xD4, 0x00, 0x50, 0xE4, 0xC6, 0x42, 0x6F)

let kIOUSBDeviceInterfaceID = CFUUIDGetConstantUUIDWithBytes(kCFAllocatorDefault,
                                                             0x5c, 0x81, 0x87, 0xd0, 0x9e, 0xf3, 0x11, 0xD4,
                                                             0x8b, 0x45, 0x00, 0x0a, 0x27, 0x05, 0x28, 0x61)


// Create dictionary with IOUSBDevice as IOProviderClass.
let matchingDictionary: NSMutableDictionary = IOServiceMatching(kIOUSBDeviceClassName)

// Get iterator for matching USB devices.
var usbIterator = io_iterator_t()
let matchingServicesResult = IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDictionary, &usbIterator)
if matchingServicesResult != kIOReturnSuccess {
    print("Error getting deviceList!")
    exit(EXIT_FAILURE)
}

// Iterate devices until usbDevice == 0.
var usbDevice = IOIteratorNext(usbIterator)
while usbDevice != 0 {
    defer {
        usbDevice = IOIteratorNext(usbIterator)
    }

    // io_name_t imports to Swift as a tuple (Int8, ..., Int8) with 128 ints
    // although in device_types.h it is defined as
    //      typedef char io_name_t[128];
    var deviceNameCString = [CChar](repeating: 0, count: MemoryLayout<io_name_t>.size)
    let deviceNameResult = IORegistryEntryGetName(usbDevice, &deviceNameCString)
    if deviceNameResult != kIOReturnSuccess {
        print("Error getting device name")
        continue
    }
    let deviceName = String(cString: &deviceNameCString)
    print("USB device name: \(deviceName)")

    // Get plug-in interface for current USB device
    var plugInInterfacePtrPtr: UnsafeMutablePointer<UnsafeMutablePointer<IOCFPlugInInterface>?>?
    var score: Int32 = 0
    let plugInInterfaceResult = IOCreatePlugInInterfaceForService(
        usbDevice,
        kIOUSBDeviceUserClientTypeID,
        kIOCFPlugInInterfaceID,
        &plugInInterfacePtrPtr,
        &score)

    // USB device object is no longer needed.
    IOObjectRelease(usbDevice)

    // Dereference pointer for the plug-in interface
    guard plugInInterfaceResult == kIOReturnSuccess,
        let plugInInterface = plugInInterfacePtrPtr?.pointee?.pointee else {
            print("Unable to get Plug-In Interface")
            continue
    }

    // Use plug-in interface to get a device interface.
    var deviceInterfacePtrPtr: UnsafeMutablePointer<UnsafeMutablePointer<IOUSBDeviceInterface>?>?
    let deviceInterfaceResult = withUnsafeMutablePointer(to: &deviceInterfacePtrPtr) {
        $0.withMemoryRebound(to: Optional<LPVOID>.self, capacity: 1) {
            plugInInterface.QueryInterface(
                plugInInterfacePtrPtr,
                CFUUIDGetUUIDBytes(kIOUSBDeviceInterfaceID),
                $0)
        }
    }

    // Plug-in interface is no longer needed.
    _ = plugInInterface.Release(plugInInterfacePtrPtr)

    // Dereference pointer for the device interface.
    guard deviceInterfaceResult == kIOReturnSuccess,
        let deviceInterface = deviceInterfacePtrPtr?.pointee?.pointee else {
            print("Unable to get Device Interface")
            continue
    }

    // Use device interface to get vendor ID.
    var usbVendorID: UInt16 = 0
    let vendorResult = deviceInterface.GetDeviceVendor(deviceInterfacePtrPtr, &usbVendorID)

    // Device interface is no longer needed:
    _ = deviceInterface.Release(deviceInterfacePtrPtr)

    if vendorResult != kIOReturnSuccess {
        print("Unable to get device Vendor ID")
        continue
    }

    print("USB Vendor ID: \(usbVendorID)")
}

exit(EXIT_SUCCESS)