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.\" Copyright (c) 2003 Joseph Koshy <jkoshy@FreeBSD.org>
.\" Copyright (c) 2006 Ceri Davies <ceri@FreeBSD.org>
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.Dd August 18, 2023
.Dt P_CANSEE 9
.Os
.Sh NAME
.Nm p_cansee
.Nd determine visibility of a process
.Sh SYNOPSIS
.In sys/proc.h
.Ft int
.Fn p_cansee "struct thread *td" "struct proc *p"
.Sh DESCRIPTION
This function determines if a given process
.Fa p
is visible to the thread
.Fa td ,
where the notion of
.Dq visibility
may be read as
.Dq "awareness of existence" .
.Pp
This function explicitly allows a thread to always see its own process,
even with pending credentials changes
.Po
see
.Xr ucred 9
.Pc .
Otherwise, it simply defers to
.Xr cr_cansee 9 .
.Sh RETURN VALUES
The
.Fn p_cansee
function
returns
.Li 0
if the process denoted by
.Fa p
is visible by thread
.Fa td ,
or ESRCH otherwise.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ESRCH
Thread
.Fa td
is not part of process
.Fa p
and cannot see it as determined by
.Xr cr_cansee 9 .
.El
.Sh SEE ALSO
.Xr ucred 9 ,
.Xr cr_cansee 9 ,
.Xr p_candebug 9