How to enumerate USB Mass Storage devices?

Discussion in 'Windows Vista Drivers' started by Wan-Hi, May 27, 2005.

  1. Wan-Hi

    Wan-Hi Guest


    i'm working on a hobby project for my own mp3 (usb mass storage) player and
    try to enumerate all usb mass storage devices currently connected to my
    computer. i've been working on this quite a while because i can't get through
    the msdn efficiently enough. i planned to identify my player like this:

    1) enumerate all disks (by SetupDiEnumDeviceInterfaces in conjunction with
    2) find out those who are mass storage devices
    3) get each mass storage device's partition info
    4) get a handle to the volume

    i chose the method above because i wanted to avoid a low level enumeration
    through the usb hubs. now i'm stuck with step 2 because i don't know how to
    find out the correct buffer size, needed by DeviceIoControl for the
    IOCTL_STORAGE_GET_MEDIA_TYPES_EX flag. the documentation didn't explain a
    proper use any further. so i wonder if any veteran can give me a hint, how to
    find out the buffer size.


    Wan-Hi, May 27, 2005
    1. Advertisements

  2. Enumerate the volumes (GUID_DEVINTERFACE_VOLUME),
    SetupDiGetDeviceInterfaceDetail gives you the DevInst. Call
    CM_Get_Parent twice to get the grandparent DevInst, call
    CM_Get_Device_ID and analyze the string returned. If it starts with
    "USB\" then it is a USB stick.
    This is also the DevInst to call CM_Request_Device_Eject on for safe
    removal of the stick.

    For additional tricks get the "SymbolicName" via CM_Open_DevNode_Key and
    RegQueryValueEx. The returned string contains VID, PID and SerialNumber
    to identify a stick individually.

    The USBVIEW way of getting the info directly from the device is a bit
    disruptive and may cause spurious surprise removal dialogs.
    Robert Marquardt, May 27, 2005
    1. Advertisements

  3. Wan-Hi

    Wan-Hi Guest

    Thank you very much. That helped a lot.

    I noticed that the ConfigManager functions you mention are obsolete and no
    longer documented. I looked up the declarations in the header file, but they
    are hardly described. Therefore I used SetupDiGetDeviceRegistryProperty in
    conjunction with the parent's and grandparent's SP_DEVINFO_DATA.
    Unfortunately this function doesn't accept self-constructed SP_DEVINFO_DATA
    structs, although I set the right DEVINST and class GUID, so I had to
    enumerate them separately.

    I wonder how to close the bridge between the Device Installation functions
    and the Volume Management functions. When enumerating all devices that expose
    GUID_DEVINTERFACE_VOLUME the path value in each
    can't use the path value to retrieve the mount points of a specific volume.
    Why is that so? I can create a file with that value, but can't use it for
    querying mount points? I tried to go over the Removable Storage Manager by
    using GetVolumesFromDrive, but that didn't work either.
    Wan-Hi, May 29, 2005
  4. Wan-Hi

    Wan-Hi Guest

    to clear things up i should mention that i intend to stay in user mode.
    Wan-Hi, May 29, 2005
  5. Feed the original DevicePath you got from
    SetupDiGetDeviceInterfaceDetail to GetVolumeNameForVolumeMountPoint.
    The only thing to do it to add a trailing backslath to the DevicePath first.
    If you want to match to drive letters then feed "A:\\" through "Z:\\" to
    GetVolumeNameForVolumeMountPoint and see if the result matches the above

    The main drawback is that the Volume Mount Point API is XP only.
    Robert Marquardt, May 29, 2005
  6. Wan-Hi

    Pavel A. Guest

    From the MSDN - GetVolumeNameForVolumeMountPoint, GetVolumePathName exist
    also in Win2k. GetVolumePathNamesForVolumeName exists from XP up.

    Pavel A., May 29, 2005
  7. Wan-Hi

    Wan-Hi Guest

    unfortunately it does not. this is the output N:\ is the same device as the
    one i enumerated in the volume device info set. the values are different.

    could the mount manager IOCTL codes help me?

    N:\ is mount point for: \\?\Volume{ad0dea5a-a3a8-11d9-9fbc-00110928c06d}\
    Wan-Hi, May 30, 2005
  8. Wan-Hi

    Wan-Hi Guest

    i figured out what you meant. thank you a lot.
    Wan-Hi, May 31, 2005
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.