c - 如何手动处理MacBook上所有插入的USB设备

Question

我的问题是我想手动处理插入 USB 设备时的处理方式。我不希望操作系统对插入的 USB 设备执行任何操作，除了在插入时通知我其类型和 ID 之外它们已插入。然后我可以从那里选择要应用的适当驱动程序，或者使用自定义代码手动对其执行某些操作。

我已阅读 this关于 MacOS 如何处理 USB，它说:

If you want your driver selected above others, all you need to do is add key value pairs for the device your driver is for which cause your driver to get a really high score. Usually it's enough to just put keys in for your vendor id/model. However, I think you can override the matching method (device drivers are written in a restricted set of C++) to give your driver a really high score.

我还发现了这 3 个库，用于获取有关 USB 驱动器中的内容的通知:

• https://github.com/tessel/node-usb
• https://github.com/MadLittleMods/node-usb-detection
• https://github.com/node-hid/node-hid

我只是不确定这些库是否会在发生任何事情之前(在自动选择并应用任何设备驱动程序之前)中断操作系统处理的所有 USB 设备。我希望除了我能够访问上述库之一中的设备及其类型之外什么都不会发生，但我不确定他们是否会这样做。

除此之外我没有太多代码:

var usb = require('usb')
usb.getDeviceList()

但我想这将在操作系统已经选择并应用默认驱动程序之后解决插入的设备问题。我想做这样的事情:

usb.blockDefaultOSDeviceHandler()
usb.on('device:plugged_in', function(data){
  if (data.type == 'keyboard') {
    if (data.modelNumber == '123') {
      // allow
      usb.applyKeyboardDriver('abc', data.modelNumber)
      usb.on('keyboard:event', logKeyboardEvent)
    } else {
      throw new Error('Unrecognized device')
    }
  } 
})

我希望该库能够中断操作系统的所有默认行为，这样我就可以自己处理插入 USB 设备时应该执行的操作。原因可能是因为 USB 设备是一个键盘，它会自动开始输入某些键。我想知道它是键盘，需要密码和我预先批准的特定驱动程序。诸如此类的事情。

我希望在操作系统应用其默认处理规则之前访问任何新插入的 USB 设备。然后能够编写代码来手动处理每个插入的设备的操作。

如果它只能在 C 语言中实现，那么知道如何在 C 语言中实现它会比使用 Node.js 更好。

• https://github.com/Arti3DPlayer/USBDeviceSwift
• https://github.com/USBGuard/usbguard
• How to block/unlock USB port in mac os x programatically without reboot
• https://apple.stackexchange.com/questions/59764/how-to-disable-individual-usb-ports-by-script
• https://serverfault.com/questions/566687/blocking-usb-through-gpo-in-2008-r2-excluding-certain-users
• https://github.com/google/gousb
• https://github.com/IntergatedCircuits/USBDevice

Answer 1

答案就在 Apple 关于 USB 设备的文档中。基本上，您想要覆盖自定义驱动程序中的 probe 函数，让它返回最高分数，以便覆盖所有其他驱动程序，并像平常一样实现驱动程序。 Here是一些有关驱动程序选择和实例化过程的有用文档。

Before a device—or any service provider—can be used, a driver for it must be found and loaded into the kernel. The I/O Kit defines a flexible, three-phase matching process that narrows a pool of candidate drivers down to one or more drivers. The final candidate (or, if multiple candidates, the m ost eligible one) is then loaded and given the first opportunity to manage the device or service provider.

...

Each device driver, considered as a loadable kernel extension (KEXT), must define one or more personalities that specify the kinds of devices it can support.

...

Because a driver can contain multiple matching dictionaries, each one defining a different personality for the driver, the same driver code can be loaded for different devices. For purposes of competition, the I/O Kit treats each personality as if it were a driver. If, in any single personality, all of the properties required by the family match, the driver’s code is loaded and given a chance to run for that device.

...

One common property of personalities is the probe score. A probe score is an integer that reflects how well-suited a driver is to drive a particular device. A driver may have an initial probe-score value in its personality and it may implement a probe function that allows it to modify this default value, based on its suitability to drive a device. As with other matching values, probe scores are specific to each family. That’s because once matching proceeds past the class-matching stage, only personalities from the same family compete. For more information on probe scores and what a driver does in the probe function, see Device Probing.

...

At boot time and at any time devices are added or removed, the process of driver matching occurs for each detected device (or other service provider). The process dynamically locates the most suitable driver in /System/Library/Extensions for the device or service.

...

As described in Driver Matching in the chapter Architectural Overview the matching process is triggered when a bus controller driver scans its bus and detects a new device attached to it. For each detected device the controller driver creates a nub. The I/O Kit then initiates the matching process and obtains the values from the device to use in matching (for example, examining the PCI registers). Once a suitable driver is found for the nub, the driver is registered and loaded. That driver, in turn, may create its own nub (possibly through behavior inherited from its family), which initiates the matching process to find a suitable driver.

...

The matching process proceeds as follows:

1. In the class matching step, the I/O Kit narrows the list of potential drivers by eliminating any drivers of the wrong class for the provider service (that is, the nub). For example, all driver objects that descend from a SCSI class can be ruled out when the search is for a USB driver.
2. In the passive matching step, the driver’s personality (specified in a driver’s XML information property list) is examined for properties specific to the provider’s family. For example, the personality might specify a particular vendor name.
3. In the active matching step, the driver’s probe function is called with reference to the nub it is being matched against. This function allows the driver to communicate with the device and verify that it can in fact drive it. The driver returns a probe score that reflects its ability to drive the device. See Device Probing for more information. During active matching, the I/O Kit loads and probes all candidate drivers, then sorts them in order of highest to lowest probe score.

...

The I/O Kit then chooses the remaining driver with the highest probe score and starts it. If the driver successfully starts, it is added to the I/O Registry and any remaining driver candidates are discarded. If it does not start successfully, the driver with the next highest probe score is started, and so on. If more than one driver is in the pool of possible candidates, the more generic driver typically loses out to the more specific driver if both claim to be able to drive the device.

...

The probe score is a signed 32-bit integer initialized to a value specified in the driver’s personality (or to zero if not explicitly initialized).

...

A driver, in its probe function, returns a driver object (IOService *) if the probe was successful and returns zero otherwise. The returned object is usually the driver itself, but the driver can return another driver that is more suited to the provider. The probe score is an in-out parameter, which probe can modify based on what it discovers about the device.

...

After all drivers have probed the device, the one with the highest probe score is attached and its startfunction, which must be implemented by all drivers, is invoked. The start function initializes the device hardware and prepares it for operation. If the driver succeeds in starting, it returns true; the remaining candidate driver instances are discarded and the driver that started successfully continues operating. If the driver cannot initialize the hardware it must leave the hardware in the state it was in when start was invoked and return false. The failing driver is then detached and discarded, and the candidate driver with the next highest probe score is given a chance to start.

这不能用 Node.js 来完成，除非(可能)使用 Node 中的 C/C++ 扩展。