LockDisk is a CDev (control panel device) that changes your system disk (the one from which you boot your Macintosh) to read-only status. This can be handy in many ways:
Ñ CD-ROM discs are read-only. You can test such things as Hypercard stacks to make sure that they run on read-only media.
Ñ You can╒t get a virus infection on a read-only disk.
Ñ Kids can╒t (logically) destroy your hard disk. No promises on physical efforts...
Ñ Trade shows.
LockDisk cheats and goes behind the Finder╒s back. Use it with a certain sense of caution. Poorly written programs get very upset if they are run on a read-only disk. They can crash.
When you are booting your system, LockDisk looks for a file named
file used by LockDisk cdev/init
in the System Folder. If this file exists, your system disk is locked. If the file doesn╒t exist, nothing happens.
To change the behavior, open up the control panel and choose LockDisk. If you select ╥Lock╙, the file mentioned above is created, and your system disk is locked. If you select ╥Unlock╙, the file is deleted and the system disk is unlocked. This happens immediately; you don╒t have to reboot to have it take effect.
Technoweenie explanation of what╒s going on: LockDisk sets the vcbAtrb flag that indicates that the disk in question is hardware locked. Why don╒t we allow you to lock & unlock other volumes? Because the INIT can╒t handle it; at INIT time, only the system disk has been mounted, so it╒s the only disk we can see.
The Finder may not notice that the status of the disk has changed until you do something like a ╥Get Info╙ on the disk.
Questions, comments, etc. should be directed electronically to:
blob@apple.com on Internet. (preferred)
BECHTEL1 on AppleLink.
Don╒t call me, I╒ll call you. This is not an Apple product, and Apple doesn╒t know or care about this program. Leave them out of this.
In the future (not implemented yet): support disks other than the system disk, even though the lock will only be in effect until you reboot.
