如何使用libusb正确释放设备列表？

如何解决如何使用libusb正确释放设备列表？

我正在尝试使用c ++语言使用Visual Studio 2019项目类型为Console App从USB设备类型Cypress FX3读取和写入代码。在程序执行过程中，我一次调用libusb_get_device_list，一旦打开所需的设备，便立即调用libusb_free_device_list（devs，1）以释放列表。 我以为这样可以释放所有设备，但是在程序结束时，我在终端收到一条消息：

libusb: warning [libusb_exit] some libusb_devices were leaked 

我尝试打印设备列表，但是它是空的，在其他任何地方都没有将其称为get_device_list函数。我也尝试寻找类似的问题，但发现的几个问题对我没有帮助。如果有人能指出我在做什么错，并向我解释我是否应该释放此列表，我将不胜感激。

这是我的代码的主要部分，会产生此错误：

#include <iostream>
#include "libusb.h"


constexpr auto VID = 0x04B4;
constexpr auto PID = 0x00F0;
constexpr auto OUT_ENDPOINT_ID = 1;
constexpr auto IN_ENDPOINT_ID = 1;
constexpr auto SIZE_OF_PACKET = 4;

using namespace std;

struct libusb_device_descriptor DeviceDescriptor;

libusb_device** devs; //pointer to pointer of device,used to retrieve a list of devices
libusb_context* context = NULL; //a libusb session
libusb_device_handle* DeviceHandle = NULL; //a device handle


int main()
{
    int RetVal = libusb_init(&context); //initialize a library session
    ssize_t NumberOfDevices; //holding number of devices in list

    libusb_set_debug(context,3); //set verbosity level to 3,as suggested in the documentation

    NumberOfDevices = libusb_get_device_list(context,&devs); //get the list of devices

    DeviceHandle = libusb_open_device_with_vid_pid(context,VID,PID); //these are vendorID and productID for Cypress FX3 specific device

    libusb_free_device_list(devs,1); //free the list,unref the devices in it

    unsigned char* DataOut = new unsigned char[4]; //data to write

    DataOut[0] = 'a'; DataOut[1] = 'b'; DataOut[2] = 'c'; DataOut[3] = 'd'; //some dummy values

    int BytesWritten; //used to find out how many bytes were written

    if (libusb_kernel_driver_active(DeviceHandle,0) == 1) { //find out if kernel driver is attached
        cout << "Kernel Driver Active" << endl;

        if (libusb_detach_kernel_driver(DeviceHandle,0) == 0) //detach it
            cout << "Kernel Driver Detached!" << endl;
    }

    RetVal = libusb_claim_interface(DeviceHandle,0); //claim interface 0 (the first) of device (desired device has only 1)

    RetVal = libusb_bulk_transfer(DeviceHandle,(OUT_ENDPOINT_ID | LIBUSB_ENDPOINT_OUT),DataOut,SIZE_OF_PACKET,&BytesWritten,0); //the out endpoint of current device is 1

    unsigned char* DataIn = new unsigned char[4]; //data to write
    int BytesRead;
    RetVal = libusb_bulk_transfer(DeviceHandle,(IN_ENDPOINT_ID | LIBUSB_ENDPOINT_IN),DataIn,sizeof(DataIn),&BytesRead,0);
    if (RetVal == 0 && BytesRead == sizeof(DataIn)) {
        // results of the transaction can now be found in the data buffer
        // parse them here and report button press

        cout << "Read Successful! Data is: " << DataIn[0] << DataIn[1] << DataIn[2] << DataIn[3] << endl;
    }
    else {
        cout << "Read Error" << endl;
    }

    RetVal = libusb_release_interface(DeviceHandle,0); //release the claimed interface

    delete[] DataOut; //delete the allocated memory for data

    delete[] DataIn; //delete the allocated memory for data

    libusb_close(DeviceHandle); //close the device we opened

    libusb_exit(context); //needs to be called at the end


return 0;
}

我省略了为RetVal编写的检查，因此代码更简洁易读，在运行w程序时，函数调用的'RetVal'变量没有任何错误。

我是新来的人，第一次发布。我已经阅读了“如何问一个好问题”部分。所以我希望我写的正确。如果我做错了任何事情，请帮助我。

非常感谢您。