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Diffstat (limited to 'static/freebsd/man2/shmat.2')
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diff --git a/static/freebsd/man2/shmat.2 b/static/freebsd/man2/shmat.2 new file mode 100644 index 00000000..16d4b930 --- /dev/null +++ b/static/freebsd/man2/shmat.2 @@ -0,0 +1,154 @@ +.\" +.\" Copyright (c) 1995 David Hovemeyer <daveho@infocom.com> +.\" +.\" 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 DEVELOPERS ``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 DEVELOPERS 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. +.\" +.Dd January 14, 2019 +.Dt SHMAT 2 +.Os +.Sh NAME +.Nm shmat , +.Nm shmdt +.Nd attach or detach shared memory +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In sys/types.h +.In sys/ipc.h +.In sys/shm.h +.Ft void * +.Fn shmat "int shmid" "const void *addr" "int flag" +.Ft int +.Fn shmdt "const void *addr" +.Sh DESCRIPTION +The +.Fn shmat +system call +attaches the shared memory segment identified by +.Fa shmid +to the calling process's address space. +The address where the segment +is attached is determined as follows: +.\" +.\" These are cribbed almost exactly from Stevens, _Advanced Programming in +.\" the UNIX Environment_. +.\" +.Bl -bullet +.It +If +.Fa addr +is 0, the segment is attached at an address selected by the +kernel. +.It +If +.Fa addr +is nonzero and +.Va SHM_RND +is not specified in +.Fa flag , +the segment is attached the specified address. +.It +If +.Fa addr +is specified and +.Va SHM_RND +is specified, +.Fa addr +is rounded down to the nearest multiple of SHMLBA. +.El +.Pp +If the +.Va SHM_REMAP +flag is specified and the passed +.Fa addr +is not +.Dv NULL , +any existing mappings in the virtual addresses range are +cleared before the segment is attached. +If the flag is not specified, +.Fa addr +is not +.Dv NULL , +and the virtual address range contains +some pre-existing mappings, the +.Fn shmat +call fails. +.Pp +The +.Fn shmdt +system call +detaches the shared memory segment at the address specified by +.Fa addr +from the calling process's address space. +.Sh RETURN VALUES +Upon success, +.Fn shmat +returns the address where the segment is attached; otherwise, -1 +is returned and +.Va errno +is set to indicate the error. +.Pp +.Rv -std shmdt +.Sh ERRORS +The +.Fn shmat +system call +will fail if: +.Bl -tag -width Er +.It Bq Er EINVAL +No shared memory segment was found corresponding to +.Fa shmid . +.It Bq Er EINVAL +The +.Fa addr +argument +was not an acceptable address. +.It Bq Er ENOMEM +The specified +.Fa addr +cannot be used for mapping, for instance due to the amount of available +space being smaller than the segment size, +or because pre-existing mappings are in the range and no +.Va SHM_REMAP +flag was provided. +.It Bq Er EMFILE +Failed to attach the shared memory segment because the per-process +.Va kern.ipc.shmseg +.Xr sysctl 3 +limit was reached. +.El +.Pp +The +.Fn shmdt +system call +will fail if: +.Bl -tag -width Er +.It Bq Er EINVAL +The +.Fa addr +argument +does not point to a shared memory segment. +.El +.Sh "SEE ALSO" +.Xr shmctl 2 , +.Xr shmget 2 |