1.\" 2.\" Copyright (c) 2003 Joseph Koshy <jkoshy@FreeBSD.org> 3.\" Copyright (c) 2006 Ceri Davies <ceri@FreeBSD.org> 4.\" 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 17.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 20.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26.\" 27.Dd August 18, 2023 28.Dt P_CANSEE 9 29.Os 30.Sh NAME 31.Nm p_cansee 32.Nd determine visibility of a process 33.Sh SYNOPSIS 34.In sys/proc.h 35.Ft int 36.Fn p_cansee "struct thread *td" "struct proc *p" 37.Sh DESCRIPTION 38This function determines if a given process 39.Fa p 40is visible to the thread 41.Fa td , 42where the notion of 43.Dq visibility 44may be read as 45.Dq "awareness of existence" . 46.Pp 47This function explicitly allows a thread to always see its own process, 48even with pending credentials changes 49.Po 50see 51.Xr ucred 9 52.Pc . 53Otherwise, it simply defers to 54.Xr cr_cansee 9 . 55.Sh RETURN VALUES 56The 57.Fn p_cansee 58function 59returns 60.Li 0 61if the process denoted by 62.Fa p 63is visible by thread 64.Fa td , 65or ESRCH otherwise. 66.Sh ERRORS 67.Bl -tag -width Er 68.It Bq Er ESRCH 69Thread 70.Fa td 71is not part of process 72.Fa p 73and cannot see it as determined by 74.Xr cr_cansee 9 . 75.El 76.Sh SEE ALSO 77.Xr cr_cansee 9 , 78.Xr p_candebug 9 , 79.Xr ucred 9 80