The plock() function allows the calling process to lock or unlock into memory its text segment (text lock), its data segment (data lock), or both its text and data segments (process lock). Locked segments are immune to all routine swapping. The effective user ID of the calling process must be super-user to use this call.

The plock() function performs the function specified by op:

PROCLOCK

Lock text and data segments into memory (process lock).

TXTLOCK

Lock text segment into memory (text lock).

DATLOCK

Lock data segment into memory (data lock).

UNLOCK

Remove locks.

Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.

The plock() function fails and does not perform the requested operation if:

EAGAIN

Not enough memory.

EINVAL

The op argument is equal to PROCLOCK and a process lock, a text lock, or a data lock already exists on the calling process; the op argument is equal to TXTLOCK and a text lock or a process lock already exists on the calling process; the op argument is equal to DATLOCK and a data lock or a process lock already exists on the calling process; or the op argument is equal to UNLOCK and no lock exists on the calling process.

EPERM

The effective user of the calling process is not super-user.

The mlock(3C) and mlockall(3C) functions are the preferred interfaces for process locking.

See attributes(5) for descriptions of the following attributes:

exec(2), exit(2), fork(2), memcntl(2), mlock(3C), mlockall(3C), attributes(5)