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.\" Copyright (c) 2013 Advanced Computing Technologies LLC
.\" Written by: John H. Baldwin <jhb@FreeBSD.org>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd September 19, 2013
.Dt PROCCTL 2
.Os
.Sh NAME
.Nm procctl
.Nd control processes
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/procctl.h
.Ft int
.Fn procctl "idtype_t idtype" "id_t id" "int cmd" "void *arg"
.Sh DESCRIPTION
The
.Fn procctl
system call provides for control over processes.
The
.Fa idtype
and
.Fa id
arguments specify the set of processes to control.
If multiple processes match the identifier,
.Nm
will make a
.Dq best effort
to control as many of the selected possibles as possible.
An error is only returned if no selected processes successfully complete
the request.
The following identifier types are supported:
.Bl -tag -width "Dv P_PGID"
.It Dv P_PID
Control the process with the process ID
.Fa id .
.It Dv P_PGID
Control processes belonging to the process group with the ID
.Fa id .
.El
.Pp
The control request to perform is specified by the
.Fa cmd
argument.
The following commands are supported:
.Bl -tag -width "Dv PROC_SPROTECT"
.It Dv PROC_SPROTECT
Set process protection state.
This is used to mark a process as protected from being killed if the system
exhausts available memory and swap.
The
.Fa arg
parameter must point to an integer containing an operation and zero or more
optional flags.
The following operations are supported:
.Bl -tag -width "Dv PPROT_CLEAR"
.It Dv PPROT_SET
Mark the selected processes as protected.
.It Dv PPROT_CLEAR
Clear the protected state of selected processes.
.El
.Pp
The following optional flags are supported:
.Bl -tag -width "Dv PPROT_DESCE"
.It Dv PPROT_DESCEND
Apply the requested operation to all child processes of each selected process
in addition to each selected process.
.It Dv PPROT_INHERIT
When used with
.Dv PPROT_SET ,
mark all future child processes of each selected process as protected.
Future child processes will also mark all of their future child processes.
.El
.El
.Sh RETURN VALUES
If an error occurs, a value of -1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
The
.Fn procctl
system call
will fail if:
.Bl -tag -width Er
.It Bq Er EFAULT
The
.Fa arg
points outside the process's allocated address space.
.It Bq Er EINVAL
The
.Fa cmd
argument specifies an unsupported command.
.Pp
The
.Fa idtype
argument specifies an unsupported identifier type.
.It Bq Er EPERM
The calling process does not have permission to perform the requested
operation on any of the selected processes.
.It Bq Er ESRCH
No processes matched the requested
.Fa idtype
and
.Fa id .
.It Bq Er EINVAL
An invalid operation or flag was passed in
.Fa arg
for a
.Dv PROC_SPROTECT
command.
.El
.Sh SEE ALSO
.Xr ptrace 2
.Sh HISTORY
The
.Fn procctl
function appeared in
.Fx 10 .
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