1*ca2413d2SRick Parrish.\" 2*ca2413d2SRick Parrish.\" Copyright (c) 2024 Rick Parrish <unitrunker@unitrunker.net> 3*ca2413d2SRick Parrish.\" 4*ca2413d2SRick Parrish.\" SPDX-License-Identifier: BSD-2-Clause 5*ca2413d2SRick Parrish.\" 6*ca2413d2SRick Parrish.Dd December 18, 2025 7*ca2413d2SRick Parrish.Dt MQ_GETFD_NP 3 8*ca2413d2SRick Parrish.Os 9*ca2413d2SRick Parrish.Sh NAME 10*ca2413d2SRick Parrish.Nm mq_getfd_np 11*ca2413d2SRick Parrish.Nd get a file descriptor for an open message queue descriptor 12*ca2413d2SRick Parrish.Sh SYNOPSIS 13*ca2413d2SRick Parrish.Lb librt 14*ca2413d2SRick Parrish.In mqueue.h 15*ca2413d2SRick Parrish.Ft int 16*ca2413d2SRick Parrish.Fn mq_getfd_np "mqd_t mqd" 17*ca2413d2SRick Parrish.Sh DESCRIPTION 18*ca2413d2SRick ParrishThe 19*ca2413d2SRick Parrish.Nm 20*ca2413d2SRick Parrishfunction retrieves the underlying file descriptor 21*ca2413d2SRick Parrishfrom the given message queue descriptor returned from 22*ca2413d2SRick Parrish.Xr mq_open 2 . 23*ca2413d2SRick ParrishThe file descriptor is used by other functions 24*ca2413d2SRick Parrishto refer to that message queue. 25*ca2413d2SRick ParrishThe 26*ca2413d2SRick Parrish.Fa mqd 27*ca2413d2SRick Parrishargument must be an open message queue descriptor. 28*ca2413d2SRick Parrish.Sh IMPLEMENTATION NOTES 29*ca2413d2SRick Parrish.Fx 30*ca2413d2SRick Parrishimplements retrieval or alteration of message queue attributes 31*ca2413d2SRick Parrishbased on the file descriptor. 32*ca2413d2SRick ParrishThe open file descriptor is copied into a child after 33*ca2413d2SRick Parrish.Xr fork 2 . 34*ca2413d2SRick ParrishThe 35*ca2413d2SRick Parrish.Xr fstat 2 , 36*ca2413d2SRick Parrish.Xr fchmod 2 , 37*ca2413d2SRick Parrishand 38*ca2413d2SRick Parrish.Xr fchown 2 39*ca2413d2SRick Parrishsystem calls are supported for the file descriptor. 40*ca2413d2SRick Parrish.Pp 41*ca2413d2SRick ParrishThe file descriptor is safe to use so long as 42*ca2413d2SRick Parrishthe message queue descriptor remains open. 43*ca2413d2SRick Parrish.Sh RETURN VALUES 44*ca2413d2SRick ParrishUpon successful completion, the function returns a file descriptor. 45*ca2413d2SRick Parrish.Sh ERRORS 46*ca2413d2SRick ParrishThe 47*ca2413d2SRick Parrish.Nm 48*ca2413d2SRick Parrishfunction does not return any errors. 49*ca2413d2SRick Parrish.Sh SEE ALSO 50*ca2413d2SRick Parrish.Xr mq_close 2 , 51*ca2413d2SRick Parrish.Xr mq_open 2 , 52*ca2413d2SRick Parrish.Xr mqueuefs 4 53*ca2413d2SRick Parrish.Sh HISTORY 54*ca2413d2SRick ParrishSupport for the 55*ca2413d2SRick Parrish.Nm 56*ca2413d2SRick Parrishfunction first appeared in 57*ca2413d2SRick Parrish.Fx 11.0 . 58