Interrupt 21h Function 440Dh Minor Code
4Bh
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
Parameters
LockLevel
Level of the
lock. This parameter must be either 0, 1, 2, or 3.
DriveNum
Drive to
lock. This parameter must be one of these values (same device unit numbers as
for Interrupt 13h):
|
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). |
Permissions
Operations
that the system permits while the volume is locked. This parameter is specified
only when a level 1 lock is obtained or when a level 0 lock is obtained for the
second time for formatting the volume. For other lock levels, this parameter is
zero. When a level 1 lock is obtained, bits 0 and 1 of this parameter specify
whether the system permits write operations, new file mappings, or both by
other processes during a level 1 lock as well as during level 2 and 3 locks. If
this parameter specifies that write operations, new file mappings, or both are
failed, these operations are failed during level 1, 2, and 3 locks. This
parameter has the following form:
|
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). |
Return Value
Clears the
carry flag if successful. Otherwise, the function sets the carry flag and sets
the AX register to an error value.
Remarks
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.