#ifndef _NTIOAPI_H

// Input structure for IOCTL_MOUNTMGR_NEXT_DRIVE_LETTER.
typedef struct _MOUNTMGR_DRIVE_LETTER_TARGET
{
    USHORT DeviceNameLength;
    _Field_size_bytes_(DeviceNameLength) WCHAR DeviceName[1];
} MOUNTMGR_DRIVE_LETTER_TARGET, *PMOUNTMGR_DRIVE_LETTER_TARGET;

#endif
View code on GitHub

// mountmgr.h

typedef struct _MOUNTMGR_DRIVE_LETTER_TARGET {
  USHORT DeviceNameLength;
  WCHAR  DeviceName[1];
} MOUNTMGR_DRIVE_LETTER_TARGET, *PMOUNTMGR_DRIVE_LETTER_TARGET;
View the official Windows Driver Kit DDI reference

NtDoc

This structure is documented in Windows Driver Kit.

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Windows Driver Kit DDI reference (ns-mountmgr-_mountmgr_drive_letter_target)

Description

The MOUNTMGR_DRIVE_LETTER_TARGET structure is used by a mount manager client with an IOCTL_MOUNTMGR_NEXT_DRIVE_LETTER request to furnish a nonpersistent target device name to the mount manager.

Members

`DeviceNameLength`

Contains the length, in bytes, of device name.

`DeviceName`

Contains the nonpersistent target device name.

Remarks

The mount manager responds to the IOCTL_MOUNTMGR_NEXT_DRIVE_LETTER request by furnishing the client with a drive letter for the target device.

Nonpersistent target names must contain the full path of a target object name in the system object tree. For example: "\Device\HarddiskVolume1".

For more information, see Supporting Mount Manager Requests in a Storage Class Driver.

MOUNTMGR_DRIVE_LETTER_TARGET - NtDoc