Add man pages for the SYSV shm* and sem* functions.

This partially closes PR # docs/177.
This should probably also go into 2.1.

Submitted by:	daveho@infocom.com (David Hovemeyer)

7 files changed, 890 insertions, 1 deletions

diff --git a/lib/libc/sys/Makefile.inc b/lib/libc/sys/Makefile.inc
index 05cc6e8..dc65844 100644
--- a/lib/libc/sys/Makefile.inc
+++ b/lib/libc/sys/Makefile.inc
@@ -94,9 +94,11 @@ MAN2+=	sys/accept.2 sys/access.2 sys/acct.2 sys/adjtime.2 sys/bind.2 \
 	sys/nfssvc.2 sys/open.2 sys/pathconf.2 sys/pipe.2 sys/profil.2 \
 	sys/quotactl.2 sys/read.2 sys/readlink.2 sys/reboot.2 sys/recv.2 \
 	sys/rename.2 sys/revoke.2 sys/rmdir.2 sys/rtprio.2 sys/select.2 \
+	sys/semctl.2 sys/semget.2 sys/semop.2 \
 	sys/send.2 sys/setgroups.2 \
 	sys/setpgid.2 sys/setregid.2 sys/setreuid.2 \
-	sys/setsid.2 sys/setuid.2 sys/shutdown.2 \
+	sys/setsid.2 sys/setuid.2 sys/shmat.2 sys/shmctl.2 sys/shmget.2 \
+	sys/shutdown.2 \
 	sys/sigaction.2 sys/sigpending.2 sys/sigprocmask.2 sys/sigreturn.2 \
 	sys/sigaltstack.2 sys/sigstack.2 sys/sigsuspend.2 sys/socket.2 \
 	sys/socketpair.2 sys/stat.2 sys/statfs.2 sys/swapon.2 sys/symlink.2 \
@@ -130,6 +132,7 @@ MLINKS+=recv.2 recvfrom.2 recv.2 recvmsg.2
 MLINKS+=send.2 sendmsg.2 send.2 sendto.2
 MLINKS+=setpgid.2 setpgrp.2
 MLINKS+=setuid.2 setegid.2 setuid.2 seteuid.2 setuid.2 setgid.2
+MLINKS+=shmat.2 shmdt.2
 MLINKS+=stat.2 fstat.2 stat.2 lstat.2
 MLINKS+=statfs.2 fstatfs.2
 MLINKS+=syscall.2 __syscall.2
diff --git a/lib/libc/sys/semctl.2 b/lib/libc/sys/semctl.2
new file mode 100644
index 0000000..fe60ce0
--- /dev/null
+++ b/lib/libc/sys/semctl.2
@@ -0,0 +1,173 @@
+.\"
+.\" 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.
+.\"
+.\" $Id$
+.\"
+.Dd September 12, 1995
+.Dt SEMCTL 2
+.Os FreeBSD
+.Sh NAME
+.Nm semctl
+.Nd control operations on a semaphore set
+.Sh SYNOPSIS
+.Fd #include <sys/types.h>
+.Fd #include <sys/ipc.h>
+.Fd #include <sys/sem.h>
+.Ft int
+.Fn "semctl" "int semid" "int semnum" "int cmd" "union semun arg"
+.Sh DESCRIPTION
+.Fn Semctl
+performs the operation indicated by
+.Fa cmd
+on the semaphore set indicated by
+.Fa semid .
+For the commands that use the
+.Fa arg
+parameter,
+.Fa "union semun"
+is defined as follows:
+.Bd -literal
+.\"
+.\" From <sys/sem.h>:
+.\"
+union semun {
+        int     val;            /* value for SETVAL */
+        struct  semid_ds *buf;  /* buffer for IPC_STAT & IPC_SET */
+        u_short *array;         /* array for GETALL & SETALL */
+};
+.Ed
+.Pp
+Commands are performed as follows:
+.\"
+.\" This section based on Stevens, _Advanced Programming in the UNIX
+.\" Environment_.
+.\"
+.Bl -tag -width IPC_RMIDXXX
+.It Dv IPC_STAT
+Fetch the semaphore set's
+.Fa "struct semid_ds" ,
+storing it in the memory pointed to by
+.Fa arg.buf .
+.It Dv IPC_SET
+Changes the
+.Fa sem_perm.uid ,
+.Fa sem_perm.gid ,
+and
+.Fa sem_perm.mode
+members of the semaphore set's
+.Fa "struct semid_ds"
+to match those of the struct pointed to by
+.Fa arg.buf .
+The calling process's effective uid must
+match either
+.Fa sem_perm.uid
+or
+.Fa sem_perm.cuid ,
+or it must have superuser privileges.
+.It IPC_RMID
+Immediately removes the semaphore set from the system.  The calling
+process's effictive uid must equal the semaphore set's
+.Fa sem_perm.uid
+or
+.Fa sem_perm.cuid ,
+or the process must have superuser priviliges.
+.It Dv GETVAL
+Return the value of semaphore number
+.Fa semnum .
+.It Dv SETVAL
+Set the value of semaphore number
+.Fa semnum
+to
+.Fa arg.val .
+.It Dv GETPID
+Return the pid of the last process to perform an operation on
+semaphore number
+.Fa semnum .
+.It Dv GETNCNT
+Return the number of processes waiting for semaphore number
+.Fa semnum Ns 's
+value to become greater than its current value.
+.It Dv GETZCNT
+Return the number of processes waiting for semaphore number
+.Fa semnum Ns 's
+value to become 0.
+.It Dv GETALL
+Fetch the value of all of the semaphores in the set into the
+array pointed to by
+.Fa arg.array .
+.It Dv SETALL
+Set the values of all of the semaphores in the set to the values
+in the array pointed to by
+.Fa arg.array .
+.El
+.Pp
+The
+.Fa "struct semid_ds"
+is defined as follows:
+.Bd -literal
+.\"
+.\" Taken straight from <sys/sem.h>.
+.\"
+struct semid_ds {
+        struct  ipc_perm sem_perm;      /* operation permission struct */
+        struct  sem *sem_base;  /* pointer to first semaphore in set */
+        u_short sem_nsems;      /* number of sems in set */
+        time_t  sem_otime;      /* last operation time */
+        long    sem_pad1;       /* SVABI/386 says I need this here */
+        time_t  sem_ctime;      /* last change time */
+                                /* Times measured in secs since */
+                                /* 00:00:00 GMT, Jan. 1, 1970 */
+        long    sem_pad2;       /* SVABI/386 says I need this here */
+        long    sem_pad3[4];    /* SVABI/386 says I need this here */
+};
+.Ed
+.Sh RETURN VALUES
+On success, when
+.Fa cmd
+is one of GETVAL, GETNCNT, or GETZCNT,
+.Fn semctl
+returns the corresponding value; otherwise, 0 is returned.
+On failure, -1 is returned, and
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+.Fn Semctl
+will fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+No semaphore set corresponds to
+.Fa semid .
+.It Bq Er EINVAL
+.Fa semnum
+is not in the range of valid semaphores for given semaphore set.
+.It Bq Er EPERM
+The calling process's effective uid does not match the uid of
+the semaphore set's owner or creator.
+.It Bq Er EACCES
+Permission denied due to mismatch between operation and mode of
+semaphore set.
+.Sh SEE ALSO
+.Xr semget 2 ,
+.Xr semop 2
diff --git a/lib/libc/sys/semget.2 b/lib/libc/sys/semget.2
new file mode 100644
index 0000000..323aef4
--- /dev/null
+++ b/lib/libc/sys/semget.2
@@ -0,0 +1,137 @@
+.\"
+.\" 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.
+.\"
+.\" $Id$
+.\"
+.Dd September 12, 1995
+.Dt SEMGET 2
+.Os FreeBSD
+.Sh NAME
+.Nm semget
+.Nd obtain a semaphore id
+.Sh SYNOPSIS
+.Fd #include <sys/types.h>
+.Fd #include <sys/ipc.h>
+.Fd #include <sys/sem.h>
+.Ft int
+.Fn "semget" "key_t key" "int nsems" "int flag"
+.Sh DESCRIPTION
+Based on the values of
+.Fa key
+and
+.Fa flag ,
+.Fn semget
+returns the identifier of a newly created or previously existing
+set of semaphores.
+.\"
+.\" This is copied verbatim from the shmget manpage.  Perhaps
+.\" it should go in a common manpage, such as .Xr ipc 2
+.\"
+The key
+is analogous to a filename: it provides a handle that names an
+IPC object.  There are three ways to specify a key:
+.Bl -bullet
+.It
+IPC_PRIVATE may be specified, in which case a new IPC object
+will be created.
+.It
+An integer constant may be specified.  If no IPC object corresponding
+to
+.Fa key
+is specified and the IPC_CREAT bit is set in
+.Fa flag ,
+a new one will be created.
+.It
+.Fn ftok
+may be used to generate a key from a pathname.  See
+.Xr ftok 3 .
+.El
+.\"
+.\" Likewise for this section, except SHM_* becomes SEM_*.
+.\"
+.Pp
+The mode of a newly created IPC object is determined by
+.Em OR Ns 'ing
+the following constants into the
+.Fa flag
+parameter:
+.Bl -tag -width XSEM_WXX6XXX
+.It Dv SEM_R
+Read access for user.
+.It Dv SEM_W
+Write access for user.
+.It Dv (SEM_R>>3)
+Read access for group.
+.It Dv (SEM_W>>3)
+Write access for group.
+.It Dv (SEM_R>>6)
+Read access for other.
+.It Dv (SEM_W>>6)
+Write access for other.
+.El
+.Pp
+If a new set of semaphores is being created,
+.Fa nsems
+is used to indicate the number of semaphores the set should contain.
+Otherwise,
+.Fa nsems
+may be specified as 0.
+.Sh RETURN VALUES
+.Fn Semget
+returns the id of a semaphore set if successful; otherwise, -1
+is returned and
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+.Fn Semget
+will fail if:
+.Bl -tag -width Er
+.\" ipcperm could fail (we're opening to read and write, as it were)
+.It Bq Er EACCES
+Access permission failure.
+.\"
+.\" sysv_sem.c is quite explicit about these, so I'm pretty sure
+.\" this is accurate
+.\"
+.It Bq Er EEXIST
+IPC_CREAT and IPC_EXCL were specified, and a semaphore set
+corresponding to
+.Fa key
+already exists.
+.It Bq Er EINVAL
+The number of semaphores requested exceeds the system imposed maximum
+per set.
+.It Bq Er ENOSPC
+Insufficiently many semaphores are available.
+.It Bq Er ENOSPC
+The kernel could not allocate a
+.Fa "struct semid_ds" .
+.It Bq Er ENOENT
+No semaphore set was found corresponding to
+.Fa key ,
+and IPC_CREAT was not specified.
+.Sh SEE ALSO
+.Xr semctl 2 ,
+.Xr semop 2
diff --git a/lib/libc/sys/semop.2 b/lib/libc/sys/semop.2
new file mode 100644
index 0000000..74fa01b
--- /dev/null
+++ b/lib/libc/sys/semop.2
@@ -0,0 +1,192 @@
+.\"
+.\" 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.
+.\"
+.\" $Id$
+.\"
+.Dd September 22, 1995
+.Dt SEMOP 2
+.Os FreeBSD
+.Sh NAME
+.Nm semop
+.Nd atomic array of operations on a semaphore set
+.Sh SYNOPSIS
+.Fd #include <sys/types.h>
+.Fd #include <sys/ipc.h>
+.Fd #include <sys/sem.h>
+.Ft int
+.Fn "semop" "int semid" "struct sembuf array[]" "unsigned nops"
+.Sh DESCRIPTION
+.Fn Semop
+atomically performs the array of operations indicated by
+.Fa array
+on the semaphore set indicated by
+.Fa semid .
+The length of
+.Fa array
+is indicated by
+.Fa nops .
+Each operation is encoded in a
+.Fa "struct sembuf" ,
+which is defined as follows:
+.Bd -literal
+.\"
+.\" From <sys/sem.h>
+.\"
+struct sembuf {
+        u_short sem_num;        /* semaphore # */
+        short   sem_op;         /* semaphore operation */
+        short   sem_flg;        /* operation flags */
+};
+.Ed
+.Pp
+For each element in
+.Fa array ,
+.Fa sem_op
+and
+.Fa sem_flg
+determine an operation to be performed on semaphore number
+.Fa sem_num
+in the set.  The values SEM_UNDO and IPC_NOWAIT may be
+.Em OR Ns 'ed
+into the
+.Fa sem_flg
+member in order to modify the behavior of the given operation.
+.Pp
+The operation performed depends as follows on the value of
+.Fa sem_op :
+.\"
+.\" This section is based on the description of semop() in
+.\" Stevens, _Advanced Programming in the UNIX Environment_.
+.\"
+.Bl -bullet
+.It
+When
+.Fa sem_op
+is positive, the semaphore's value is incremented by
+.Fa sem_op Ns 's
+value.  If SEM_UNDO is specified, the semaphore's adjust on exit
+value is decremented by
+.Fa sem_op Ns 's
+value.  A positive value for
+.Fa sem_op
+generally corresponds to a process releasing a resource
+associated with the semaphore.
+.It
+The behavior when
+.Fa sem_op
+is negative depends on the current value of the semaphore:
+.Bl -bullet
+.It
+If the current value of the semaphore is greater than or equal to
+the absolute value of
+.Fa sem_op ,
+then the value is decremented by the absolute value of
+.Fa sem_op .
+If SEM_UNDO is specified, the semaphore's adjust on exit
+value is incremented by the absolute value of
+.Fa sem_op .
+.It
+If the current value of the semaphore is less than
+.Fa sem_op Ns 's
+value, one of the following happens:
+.\" XXX a *second* sublist?
+.Bl -bullet
+.It
+If IPC_NOWAIT was specifed, then
+.Fn semop
+returns immediately with a return value of EAGAIN.
+.It
+If some other process has removed the semaphore with the IPC_RMID
+option of
+.Fn semctl ,
+then
+.Fn semop
+returns immediately with a return value of EINVAL.
+.It
+Otherwise, the calling process is put to sleep until the semaphore's
+value is greater than or equal to the absolute value of
+.Fa sem_op .
+When this condition becomes true, the semaphore's value is decremented
+by the absolute value of
+.Fa sem_op ,
+and the semaphore's adjust on exit value is incremented by the
+absolute value of
+.Fa sem_op .
+.El
+.Pp
+A negative value for
+.Fa sem_op
+generally means that a process is waiting for a resource to become
+available.
+.El
+.Pp
+.It
+When
+.Fa sem_op
+is zero, the process waits for the semaphore's value to become zero.
+If it is already zero, the call to
+.Fn semop
+can return immediately.  Otherwise, the calling process is put to 
+sleep until the semaphore's value becomes zero.
+.El
+.Pp
+For each semaphore a process has in use, the kernel maintains an
+`adjust on exit' value, as alluded to earlier.  When a process
+exits, either voluntarily or involuntarily, the adjust on exit value
+for each semaphore is added to the semaphore's value.  This can
+be used to insure that a resource is released if a process terminates
+unexpectedly.
+.Sh RETURN VALUES
+On success,
+.Fn semop
+returns 0; otherwise, -1 is returned and
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+.Fn Semop
+will fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+No semaphore set corresponds to
+.Fa semid .
+.It Bq Er EACCES
+Permission denied due to mismatch between operation and mode of
+semaphore set.
+.It Bq Er EAGAIN
+The semaphore's value was less than
+.Fa sem_op ,
+and IPC_NOWAIT was specified.
+.It Bq Er E2BIG
+Too many operations were specified.
+.It Bq Er EFBIG
+.\"
+.\" I'd have thought this would be EINVAL, but the source says
+.\" EFBIG.
+.\"
+.Fa sem_num
+was not in the range of valid semaphores for the set.
+.Sh SEE ALSO
+.Xr semget 2 ,
+.Xr semctl 2
diff --git a/lib/libc/sys/shmat.2 b/lib/libc/sys/shmat.2
new file mode 100644
index 0000000..587eebc
--- /dev/null
+++ b/lib/libc/sys/shmat.2
@@ -0,0 +1,110 @@
+.\"
+.\" 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.
+.\"
+.\" $Id$
+.\"
+.Dd August 2, 1995
+.Dt SHMAT 2
+.Os FreeBSD
+.Sh NAME
+.Nm shmat ,
+.Nm shmdt
+.Nd attach or detach shared memory
+.Sh SYNOPSIS
+.Fd #include <sys/types.h>
+.Fd #include <sys/ipc.h>
+.Fd #include <sys/shm.h>
+.Ft void *
+.Fn "shmat" "int shmid" "void *addr" "int flag"
+.Ft int
+.Fn "shmdt" "void *addr"
+.Sh DESCRIPTION
+.Fn Shmat
+attaches the shared memory segment identifed 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 SHM_RND is not specifed in
+.Fa flag ,
+the segment is attached the specified address.
+.It
+If
+.Fa addr
+is specified and SHM_RND is specified,
+.Fa addr
+is rounded down to the nearest multiple of SHMLBA.
+.El
+.Pp
+.Fn Shmdt
+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
+Upon success,
+.Fn shmdt
+returns 0; otherwise, -1 is returned and
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+.Fn Shmat
+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
+.Fa addr
+was not an acceptable address.
+.El
+.Pp
+.Fn Shmdt
+will fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+.Fa addr
+does not point to a shared memory segment.
+.Sh "SEE ALSO"
+.Xr shmget 2 ,
+.Xr shmctl 2
diff --git a/lib/libc/sys/shmctl.2 b/lib/libc/sys/shmctl.2
new file mode 100644
index 0000000..b1c5a4b
--- /dev/null
+++ b/lib/libc/sys/shmctl.2
@@ -0,0 +1,136 @@
+.\"
+.\" 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.
+.\"
+.\" $Id$
+.\"
+.Dd July 17, 1995
+.Dt SHMCTL 2
+.Os FreeBSD
+.Sh NAME
+.Nm shmctl
+.Nd shared memory control
+.Sh SYNOPSIS
+.Fd #include <sys/types.h>
+.Fd #include <sys/ipc.h>
+.Fd #include <sys/shm.h>
+.Ft int
+.Fn "shmctl" "int shmid" "int cmd" "struct shmid_ds *buf"
+.Sh DESCRIPTION
+Performs the action specified by
+.Fa cmd
+on the shared memory segment identified by
+.Fa shmid :
+.Bl -tag -width SHM_UNLOCKX
+.It Dv IPC_STAT
+Fetch the segment's
+.Fa "struct shmid_ds" ,
+storing it in the memory pointed to by
+.Fa buf .
+.\"
+.\" XXX need to make sure that this is correct for FreeBSD
+.\"
+.It Dv IPC_SET
+Changes the
+.Fa shm_perm.uid ,
+.Fa shm_perm.gid ,
+and
+.Fa shm_perm.mode
+members of the segment's
+.Fa "struct shmid_ds"
+to match those of the struct pointed to by
+.Fa buf .
+The calling process's effective uid must
+match either
+.Fa shm_perm.uid
+or
+.Fa shm_perm.cuid ,
+or it must have superuser privileges.
+.It Dv IPC_RMID
+Removes the segment from the system.  The removal will not take
+effect until all processes having attached the segment have exited;
+however, once the IPC_RMID operation has taken place, no further
+processes will be allowed to attach the segment.  For the operation
+to succeed, the calling process's effective uid must match
+.Fa shm_perm.uid
+or
+.Fa shm_perm.cuid ,
+or the process must have superuser privilges.
+.\" .It Dv SHM_LOCK
+.\" Locks the segment in memory.  The calling process must have
+.\" superuser privileges. Not implemented in FreeBSD.
+.\" .It Dv SHM_UNLOCK
+.\" Unlocks the segment from memory.  The calling process must
+.\" have superuser priviliges.  Not implemented in FreeBSD.
+.El
+.Pp
+The
+.Fa "shmid_ds" 
+struct is defined as follows:
+.\"
+.\" I fiddled with the spaces a bit to make it fit well when viewed
+.\" with nroff, but otherwise it's straight from sys/shm.h
+.\"
+.Bd -literal
+struct shmid_ds {
+    struct ipc_perm shm_perm;   /* operation permission structure */
+    int             shm_segsz;  /* size of segment in bytes */
+    pid_t           shm_lpid;   /* process ID of last shared memory op */
+    pid_t           shm_cpid;   /* process ID of creator */
+    short           shm_nattch; /* number of current attaches */
+    time_t          shm_atime;  /* time of last shmat() */
+    time_t          shm_dtime;  /* time of last shmdt() */
+    time_t          shm_ctime;  /* time of last change by shmctl() */
+    void           *shm_internal; /* sysv stupidity */
+};
+.Ed
+.Sh RETURN VALUES
+Upon successful completion,
+.Fn shmctl
+returns 0.  Otherwise, it returns -1 and
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+.Fn Shmctl
+will fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+Invalid operation, or
+no shared memory segment was found corresponding to
+.Fa shmid .
+.\"
+.\" XXX I think the following is right: ipcperm() only returns EPERM
+.\"	when an attempt is made to modify (IPC_M) by a non-creator
+.\"	non-owner
+.It Bq Er EPERM
+The calling process's effective uid does not match the uid of
+the shared memory segment's owner or creator.
+.It Bq Er EACCES
+Permission denied due to mismatch between operation and mode of
+shared memory segment.
+.Sh "SEE ALSO"
+.Xr shmget 2 ,
+.Xr shmat 2 ,
+.Xr shmdt 2 ,
+.Xr ftok 3
diff --git a/lib/libc/sys/shmget.2 b/lib/libc/sys/shmget.2
new file mode 100644
index 0000000..3df3272
--- /dev/null
+++ b/lib/libc/sys/shmget.2
@@ -0,0 +1,138 @@
+.\"
+.\" 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.
+.\"
+.\" $Id$
+.\"
+.Dd July 3, 1995
+.Dt SHMGET 2
+.Os FreeBSD
+.Sh NAME
+.Nm shmget
+.Nd obtain a shared memory identifier
+.Sh SYNOPSIS
+.Fd #include <sys/types.h>
+.Fd #include <sys/ipc.h>
+.Fd #include <sys/shm.h>
+.Ft int
+.Fn "shmget" "key_t key" "int size" "int flag"
+.Sh DESCRIPTION
+Based on the values of
+.Fa key
+and
+.Fa flag ,
+.Fn shmget
+returns the identifier of a newly created or previously existing shared
+memory segment.
+.\"
+.\" The following bit about keys and modes also applies to semaphores
+.\" and message queues.
+.\"
+The key
+is analogous to a filename: it provides a handle that names an
+IPC object.  There are three ways to specify a key:
+.Bl -bullet
+.It
+IPC_PRIVATE may be specified, in which case a new IPC object
+will be created.
+.It
+An integer constant may be specified.  If no IPC object corresponding
+to
+.Fa key
+is specified and the IPC_CREAT bit is set in
+.Fa flag ,
+a new one will be created.
+.It
+.Fn ftok
+may be used to generate a key from a pathname.  See
+.Xr ftok 3 .
+.El
+.Pp
+The mode of a newly created IPC object is determined by
+.Em OR Ns 'ing
+the following constants into the
+.Fa flag
+parameter:
+.Bl -tag -width XSHM_WXX6XXX
+.It Dv SHM_R
+Read access for user.
+.It Dv SHM_W
+Write access for user.
+.It Dv (SHM_R>>3)
+Read access for group.
+.It Dv (SHM_W>>3)
+Write access for group.
+.It Dv (SHM_R>>6)
+Read access for other.
+.It Dv (SHM_W>>6)
+Write access for other.
+.El
+.\"
+.\" XXX - we should also mention how uid, euid, and gid affect ownership
+.\"	  and use
+.\"
+.\" end section about keys and modes
+.\"
+.Pp
+When creating a new shared memory segment,
+.Fa size
+indicates the desired size of the new segment in bytes.  The size
+of the segment may be rounded up to a multiple convenient to the
+kernel (i.e., the page size).
+.Sh RETURN VALUES
+Upon successful completion,
+.Fn shmget
+returns the positive integer identifier of a shared memory segment.
+Otherwise, -1 is returned and
+.Va errno
+set to indicate the error.
+.Sh ERRORS
+.Fn Shmget
+will fail if:
+.Bl -tag -width Er
+.\"
+.\" XXX What about ipcperm failing?
+.\"
+.It Bq Er EINVAL
+Size specified is greater than the size of the previously existing segment.
+Size specified is less than the system imposed minumum, or greater than
+the system imposed maximum.
+.It Bq Er ENOENT
+No shared memory segment was found matching
+.Fa key ,
+and IPC_CREAT was not specified.
+.It Bq Er ENOSPC
+The kernel was unable to allocate enough memory to
+satisfy the request.
+.It Bq Er EEXIST
+IPC_CREAT and IPC_EXCL were specified, and a shared memory segment
+corresponding to
+.Fa key
+already exists.
+.Pp
+.Sh "SEE ALSO" 
+.Xr shmctl 2 ,
+.Xr shmat 2 ,
+.Xr shmdt 2 ,
+.Xr ftok 3