Ensures that a secure path to a terminal is provided.
| Item | Description |
|---|---|
| devno | Specifies the major and minor device numbers. |
| chan | Specifies the channel number. For a multiplexed device driver, a value of -1 in this parameter means access to all channels is to be revoked. |
| flag | Currently defined to have the value of 0. (Reserved for future extensions.) |
The ddrevoke entry point can be provided only by character class device drivers. It cannot be provided by block device drivers even when providing raw read/write access. A ddrevoke entry point is required only by device drivers supporting devices in the Trusted Computing Path to a terminal (for example, by the /dev/ lft and /dev/tty files for the low function terminal and teletype device drivers). The ddrevoke routine is called by the frevoke and revoke subroutines.
The ddrevoke routine revokes access to a specific device or channel (if the device driver is multiplexed). When called, the ddrevoke routine should terminate all processes waiting in the device driver while accessing the specified device or channel. It should terminate the processes by sending a SIGKILL signal to all processes currently waiting for a specified device or channel data transfer. The current process is not to be terminated.
If the device driver is multiplexed and the channel ID in the chan parameter has the value -1, all channels are to be revoked.
The ddrevoke routine is called in the process environment only.
The ddrevoke routine should return a value of 0 for successful completion, or a value from the /usr/include/errno.h file on error.
| Item | Description |
|---|---|
| /dev/lft | Specifies the path of the LFT special file. |
| /dev/tty | Specifies the path of the tty special file. |