Devcon Rescan命令代码实现 使用SetupAPI函数实现设备管理器重新搜索枚举系统子设备

在Windows的设备管理器工具栏有一个小电脑的图标，点击后，系统会强制设备管理器树进行更新并重新枚举卸载掉（devcon的remove用法）的设备并安装驱动程序。
这个功能在devcon.exe的源代码中有，其对应的devcon命令为

devcon.exe resan

函数原型：

• CM_Locate_DevNode_Ex，获取设备根(pDeviceID=NULL)节点的句柄

  CMAPI CONFIGRET WINAPI
  CM_Locate_DevNode_Ex(
    OUT PDEVINST  pdnDevInst,
    IN DEVINSTID  pDeviceID  OPTIONAL,
    IN ULONG  ulFlags,
    IN HMACHINE  hMachine
    );
  

• CM_Reenumerate_DevNode_Ex，枚举该节点下的所有子设备

  CMAPI CONFIGRET WINAPI
  CM_Reenumerate_DevNode_Ex(
   IN DEVINST  dnDevInst,
   IN ULONG  ulFlags,
   IN HMACHINE  hMachine
   );
  

源代码实现：

int cmdRescan(_In_ LPCTSTR BaseName, _In_opt_ LPCTSTR Machine, _In_ DWORD Flags, _In_ int argc, _In_reads_(argc) PTSTR argv[])
/*++

Routine Description:

    RESCAN
    rescan for new devices

Arguments:

    BaseName  - name of executable
    Machine   - machine name, must be NULL
    argc/argv - remaining parameters

Return Value:

    EXIT_xxxx

--*/
{

    //
    // reenumerate from the root of the devnode tree
    // totally CM based
    //
    int failcode = EXIT_FAIL;
    HMACHINE machineHandle = NULL;
    DEVINST devRoot;

    UNREFERENCED_PARAMETER(BaseName);
    UNREFERENCED_PARAMETER(Flags);
    UNREFERENCED_PARAMETER(argc);
    UNREFERENCED_PARAMETER(argv);

    if(Machine) {
        if(CM_Connect_Machine(Machine,&machineHandle) != CR_SUCCESS) {
            return failcode;
        }
    }

    if(CM_Locate_DevNode_Ex(&devRoot,NULL,CM_LOCATE_DEVNODE_NORMAL,machineHandle) != CR_SUCCESS) {
        goto final;
    }

    FormatToStream(stdout,Machine ? MSG_RESCAN : MSG_RESCAN_LOCAL);

    if(CM_Reenumerate_DevNode_Ex(devRoot, 0, machineHandle) != CR_SUCCESS) {
        goto final;
    }

    FormatToStream(stdout,MSG_RESCAN_OK);

    failcode = EXIT_OK;

final:
    if(machineHandle) {
        CM_Disconnect_Machine(machineHandle);
    }

    return failcode;
}