plock

Purpose

     Locks the process, text, or data in memory.

Syntax

     #include <sys/lock.h>

     int plock (op)
     int op;

Description

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

     The  op parameter  specifies one  of the  following oper-
     ations:

     PROCLOCK   Locks  text  and  data  segments  into  memory
                (process lock).
     TXTLOCK    Locks text segment into memory (text lock).
     DATLOCK    Locks data segment into memory (data lock).
     UNLOCK     Removes locks.

Return Value

     Upon successful completion,  a value of 0  is returned to
     the calling  process.  If plock  fails, a value of  -1 is
     returned and errno is set to indicate the error.

Diagnostics

     The plock  system call fails if  one or more of  the fol-
     lowing are true:

     EPERM      The effective  user ID of the  calling process
                is not superuser.

     EINVAL     The op  parameter has a value  other than PRO-
                CLOCK, TXTLOCK, DATLOCK, or UNLOCK.

     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  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.

Related Information

     In  this book:   "exec:   execl,  execv, execle,  execve,
     execlp, execvp,"  "exit, _exit," and  "fork."