IOCTL_MOUNTMGR_NEXT_DRIVE_LETTER IOCTL (mountmgr.h)
This IOCTL checks to see if the given volume has a drive letter. If it already has a drive letter, or if the volume has a special mount manager database entry indicating that it does not require a drive letter, this routine returns the current drive letter (if there is one) and does nothing. If the given volume does not have a drive letter and does not have a special mount manager database entry indicating that it does not require a drive letter, the next available drive letter is assigned to the volume. If the volume's nonpersistent device name begins with "\Device\Floppy", the mount manager will check for available drive letters starting with the letter "A." If the volume name begins with "\Device\CdRom" the mount manager will check for available drive letters starting with drive letter "D." In all other cases, the mount manager starts with drive letter "C."
Major code
Input buffer
The mount manager client initializes the MOUNTMGR_DRIVE_LETTER_TARGET structure at the beginning of the buffer at Irp->AssociatedIrp.SystemBuffer. The client must insert the name of the target volume at the address pointed to by the DeviceName[] member of this structure. The target volume name is the name of the nonpersistent device object associated with the volume (for example, "\Device\HarddiskVolume1").
Input buffer length
Parameters.DeviceIoControl.InputBufferLength in the I/O stack location of the IRP indicates the size, in bytes, of the input buffer, which must be greater than or equal to sizeof(MOUNTMGR_DRIVE_LETTER_TARGET).
Output buffer
The mount manager inserts either the current drive letter or the newly assigned drive letter (see previous discussion) in the MOUNTMGR_DRIVE_LETTER_INFORMATION structure at the beginning of the buffer at Irp->AssociatedIrp.SystemBuffer.
Output buffer length
Parameters.DeviceIoControl.OutputBufferLength in the I/O stack location of the IRP indicates the size, in bytes, of the output buffer, which must be greater than or equal to sizeof(MOUNTMGR_DRIVE_LETTER_INFORMATION).
Input / Output buffer
N/A
Input / Output buffer length
N/A
Status block
If the operation is successful , the Status field is set to STATUS_SUCCESS.
If InputBufferLength is less than sizeof(MOUNTMGR_DRIVE_LETTER_TARGET) or if OutputBufferLength is less than sizeof(MOUNTMGR_DRIVE_LETTER_INFORMATION), the Status field is set to STATUS_INVALID_PARAMETER.
Remarks
For more information, see Supporting Mount Manager Requests in a Storage Class Driver.
Requirements
| Requirement | Value |
|---|---|
| Header | mountmgr.h (include Mountmgr.h) |