用SetupDiGetClassDevs枚举设备

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络上有段代码是用SetupDiGetClassDevs枚举U盘对应的盘符。代码中判断设备是否是u盘的办法是首先用
GUID_DEVINTERFACE_VOLUME调用SetupDiGetClassDevs后再
SetupDiEnumDeviceInterfaces，SetupDiGetDeviceInterfaceDetail……最后还需要和事先传进来
的Device ID比较。

实际上，经过试验，我找到另外一个简单一点的办法：

首先是用
SetupDiGetClassDevs枚举GUID_DEVINTERFACE_USB_DEVICE，找到所有USB设备。然后用
SetupDiGetClassDevs枚举GUID_DEVINTERFACE_VOLUME，找到所有VOLUME后依次递归取其Parent，直到
到达HTREE/ROOT/0或者某个Parent等于前面得到的USB设备为止。

值得注意的是，GUID_DEVINTERFACE_USB_DEVICE、GUID_DEVINTERFACE_DISK枚举出的设备只有一个Child，就是自身。

下面是SetupDiGetClassDevs在我机器上的一些结果：

Volume

{4D36E965-E325-11CE-BFC1-08002BE10318}

IDE/CDROMHL-DT-ST_CD-ROM_GCR-8523B_______________1.02____/5&4DE3C4&0&0.0.0

{4D36E965-E325-11CE-BFC1-08002BE10318}

SCSI/CDROM&VEN_GENERIC&PROD_DVD-ROM&REV_1.0/2&12B1DE20&0&000

{71A27CDD-812A-11D0-BEC7-08002BE2092F}

STORAGE/REMOVABLEMEDIA/7&35EAC781&0&RM

{71A27CDD-812A-11D0-BEC7-08002BE2092F}

STORAGE/VOLUME/1&30A96598&0&SIGNATURE8150814OFFSET27FCC3000LENGTH27FCB3400

{71A27CDD-812A-11D0-BEC7-08002BE2092F}

STORAGE/VOLUME/1&30A96598&0&SIGNATURE8150814OFFSET4FF97E200LENGTH4510E1E00

{71A27CDD-812A-11D0-BEC7-08002BE2092F}

STORAGE/VOLUME/1&30A96598&0&SIGNATURE8150814OFFSET7E00LENGTH27FCB3400

Disk

{4D36E967-E325-11CE-BFC1-08002BE10318}

IDE/DISKST340015A_______________________________3.15____/4C35484158483150202020202020202020202020

{4D36E967-E325-11CE-BFC1-08002BE10318}

USBSTOR/DISK&VEN_GENERIC&PROD_USB_FLASH_DRIVE&REV_1.00/6&2ECD5725&1

USB

{36FC9E60-C465-11CF-8056-444553540000}

USB/VID_1043&PID_8012/5&1E5B5D9&0&5

PARTITION

{71A27CDD-812A-11D0-BEC7-08002BE2092F}

STORAGE/REMOVABLEMEDIA/7&35EAC781&0&RM

下面是一些VOLUME的父系层次：

{4D36E965-E325-11CE-BFC1-08002BE10318}

IDE/CDROMHL-DT-ST_CD-ROM_GCR-8523B_______________1.02____/5&4DE3C4&0&0.0.0

PCIIDE/IDECHANNEL/4&14E96D70&0&1

PCI/VEN_8086&DEV_24DB&SUBSYS_300E103C&REV_02/3&13C0B0C5&0&F9

ACPI/PNP0A03/1

ACPI_HAL/PNP0C08/0

ROOT/ACPI_HAL/0000

HTREE/ROOT/0

{4D36E965-E325-11CE-BFC1-08002BE10318}

SCSI/CDROM&VEN_GENERIC&PROD_DVD-ROM&REV_1.0/2&12B1DE20&0&000

PCI/D347PRT/0000

ROOT/SYSTEM/0003

HTREE/ROOT/0

{71A27CDD-812A-11D0-BEC7-08002BE2092F}

STORAGE/REMOVABLEMEDIA/7&35EAC781&0&RM

USBSTOR/DISK&VEN_GENERIC&PROD_USB_FLASH_DRIVE&REV_1.00/6&2ECD5725&1

USB/VID_1043&PID_8012/5&1E5B5D9&0&5

USB/ROOT_HUB20/4&386BDE3F&0

PCI/VEN_8086&DEV_24DD&SUBSYS_300E103C&REV_02/3&13C0B0C5&0&EF

ACPI/PNP0A03/1

ACPI_HAL/PNP0C08/0

ROOT/ACPI_HAL/0000

HTREE/ROOT/0

{71A27CDD-812A-11D0-BEC7-08002BE2092F}

STORAGE/VOLUME/1&30A96598&0&SIGNATURE8150814OFFSET27FCC3000LENGTH27FCB3400

ROOT/FTDISK/0000

HTREE/ROOT/0

{71A27CDD-812A-11D0-BEC7-08002BE2092F}

STORAGE/VOLUME/1&30A96598&0&SIGNATURE8150814OFFSET4FF97E200LENGTH4510E1E00

ROOT/FTDISK/0000

HTREE/ROOT/0

{71A27CDD-812A-11D0-BEC7-08002BE2092F}

STORAGE/VOLUME/1&30A96598&0&SIGNATURE8150814OFFSET7E00LENGTH27FCB3400

ROOT/FTDISK/0000

HTREE/ROOT/0

对照一下可以发现以下值得注意的地方：

1、IDE硬盘中VOLUME的设备ID包括了VOLUME的位置、长度

2、IDE硬盘中VOLUME的Parents中不包括该硬盘的Device ID

3、U盘中VOLUME的Parents中包括该U盘的Device ID

4、U盘中VOLUME的Device ID里有“REMOVABLEMEDIA”标记