NAME

plock() − lock process, text, data, stack, or shared library in memory

SYNOPSIS

#include <sys/lock.h>

int plock(int op);

DESCRIPTION

The plock() system call allows the calling process to lock the text segment of the process (text lock), its data segment (data lock), or both its text and data segment (process lock) into memory.  Stack segments are also locked when data segments are locked.  Shared library text and shared library data segments (shlib lock) can also be locked.  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 a superuser or the user must be a member of a group that has the MLOCK privilege (see getprivgrp(2) and setprivgrp(1M))

op must be one of 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

SHLIBLOCK Lock shared library text and shared library data segments (shared library lock)

PROCSHLIBLOCK Lock text, data and shared library text and shared library data segments into memory (process and shared library lock)

TXTSHLIBLOCK Lock text, shared library text and shared library data segments into memory (text and shared library lock)

DATSHLIBLOCK Lock data, shared library text and shared library data segments into memory (data and shared library lock)

RETURN VALUE

plock() returns the following values:

 0 Successful completion. 

-1 Failure.  The requested operation is not performed.  errno is set to indicate the error. 

ERRORS

If plock() fails, errno is set to one of the following values. 

[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 process lock already exists on the calling process. 

[EINVAL] op is equal to DATLOCK and a data lock, or 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 equal to SHLIBLOCK and there are no unlocked shared library segments in the calling process. 

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

[EINVAL] op is equal to TXTSHLIBLOCK and a text lock or process lock already exists on the calling process. 

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

[EINVAL] op is not equal to one of the values specified in DESCRIPTION. 

[EINVAL] plock() is not allowed in a [vfork,exec] window.  See vfork(2).

[ENOMEM] There is not enough lockable memory in the system to satisfy the locking request. 

[EPERM] The effective user ID of the calling process is not a superuser and the user does not belong to a group that has the MLOCK privilege. 

EXAMPLES

The following call to plock() locks the calling process in memory:

plock(PROCLOCK);

SEE ALSO

setprivgrp(1M), exec(2), exit(2), fork(2), getprivgrp(2), vfork(2). 

STANDARDS CONFORMANCE

plock(): SVID2, SVID3, XPG2

Hewlett-Packard Company  —  HP-UX Release 10.20:  July 1996