Locks the physical volume.
mov ax, 440Dh ; generic IOCTL
mov bh, LockLevel ; see below
mov bl, DriveNum ; see below
mov ch, 08h ; device category (must be 08h)
mov cl, 4Bh ; Lock Physical Volume
mov dx, Permissions ; see below
int 21h
jc error
00 - 7Fh | Floppy disk drive (00 for the first floppy drive, 01 for the second, and so on). |
80 - FFh | Hard disk drive (80 for the first hard disk drive, 81 for the second, and so on). |
Bit | Meaning |
---|---|
0 | 0 = Write operations are failed (specified when a level 1 lock is obtained). |
0 | 1 = Write operations are allowed (specified when a level 1 lock is obtained). |
1 | 0 = New file mapping are allowed (specified when a level 1 lock is obtained). |
1 | 1 = New file mapping are failed (specified when a level 1 lock is obtained). |
2 | 1 = The volume is locked for formatting (specified when a level 0 lock is obtained for the second time). |
Clears the carry flag if successful. Otherwise, the function sets the carry flag and sets the AX register to an error value.
The volume must be locked before the application performs direct disk write operations by using Interrupt 13h, Interrupt 26h, or the Interrupt 21h IOCTL functions. A single physical volume may be divided into more than one logical volume, which is also called a partition. The system automatically takes a logical volume lock on all logical volumes on the specified physical drive. If the application performs disk writes only to a logical drive, Lock Logical Volume (Interrupt 21h Function 440Dh Minor Code 4Ah) is used instead of this function. Unlock Physical Volume (Interrupt 21h Function 440Dh Minor Code 6Bh) should be called to release the lock.