NAME

plock − lock process, text, or data in memory

SYNOPSIS

#include <sys/lock.h>

int plock (op)
int op;

HP-UX COMPATIBILITY

Level: HP-UX/STANDARD

Origin: System V

DESCRIPTION

Plock allows the calling process to lock the text portion of the process (text lock), its data portion (data lock), or both its text and data portion (process lock) into memory.  Locked segments are immune to all routine swapping.  Plock also allows these segments to be unlocked.  The effective user ID of the calling process must be super-user, or the user must have PRIV_MLOCK (see setprivgrp(2)) to use this call. Op specifies the following:

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

Plock will fail and not perform the requested operation if one or more of the following are true:

­[EPERM] The effective user ID of the calling process is not super-user and the user does not have PRIV_MLOCK. 

­[EINVAL] Op is equal to PROCLOCK and a process lock, a text lock, or a data lock already exists on the calling process. 

­[EINVAL] Op is equal to TXTLOCK and a text lock, or a process lock already exists on the calling process. 

­[EINVAL] Op is equal to DATLOCK and a data lock, or a process lock already exists on the calling process. 

­[EINVAL] Op is equal to UNLOCK and no type of lock exists on the calling process. 

­[EINVAL] Op is not equal to either PROCLOCK, TXTLOCK, DATLOCK, or UNLOCK. 

All locks are released by fork and exec.

RETURN VALUE

Upon successful completion, a value of 0 is returned to the calling process.  Otherwise, a value of −1 is returned and errno is set to indicate the error. 

HARDWARE DEPENDENCIES

Series 200 and 500:

Plock is not allowed in the [vfork,exec] window. 

­[EINVAL] Plock not allowed in [vfork,exec] window

SEE ALSO

exec(2), exit(2), fork(2). 

Hewlett-Packard  —  last mod. May 11, 2021