usr/src/sys/kern/sysv_shm.c

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department. Originally from University of Wisconsin.
 *
 * %sccs.include.redist.c%
 *
 * from: Utah $Hdr: uipc_shm.c 1.9 89/08/14$
 *
 *	@(#)sysv_shm.c	7.8 (Berkeley) %G%
 */

/*
 * System V shared memory routines.
 * TEMPORARY, until mmap is in place;
 * needed now for HP-UX compatibility and X server (yech!).
 */

#ifdef SYSVSHM

#include "machine/pte.h"

#include "param.h"
#include "systm.h"
#include "syscontext.h"
#include "kernel.h"
#include "proc.h"
#include "vm.h"
#include "shm.h"
#include "mapmem.h"
#include "malloc.h"

#ifdef HPUXCOMPAT
#include "../hpux/hpux.h"
#endif

int	shmat(), shmctl(), shmdt(), shmget();
int	(*shmcalls[])() = { shmat, shmctl, shmdt, shmget };
int	shmtot = 0;

int	shmfork(), shmexit();
struct	mapmemops shmops = { shmfork, (int (*)())0, shmexit, shmexit };

shminit()
{
	register int i;

	if (shminfo.shmmni > SHMMMNI)
		shminfo.shmmni = SHMMMNI;
	for (i = 0; i < shminfo.shmmni; i++) {
		shmsegs[i].shm_perm.mode = 0;
		shmsegs[i].shm_perm.seq = 0;
	}
}

/*
 * Entry point for all SHM calls
 */
shmsys(p, uap, retval)
	struct proc *p;
	struct args {
		u_int which;
	} *uap;
	int *retval;
{

	if (uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0]))
		RETURN (EINVAL);
	RETURN ((*shmcalls[uap->which])(p, &uap[1], retval));
}

/*
 * Get a shared memory segment
 */
shmget(p, uap, retval)
	struct proc *p;
	register struct args {
		key_t key;
		int size;
		int shmflg;
	} *uap;
	int *retval;
{
	register struct shmid_ds *shp;
	register struct ucred *cred = u.u_cred;
	register int i;
	int error, size, rval = 0;
	caddr_t kva;

	/* look up the specified shm_id */
	if (uap->key != IPC_PRIVATE) {
		for (i = 0; i < shminfo.shmmni; i++)
			if ((shmsegs[i].shm_perm.mode & SHM_ALLOC) &&
			    shmsegs[i].shm_perm.key == uap->key) {
				rval = i;
				break;
			}
	} else
		i = shminfo.shmmni;

	/* create a new shared segment if necessary */
	if (i == shminfo.shmmni) {
		if ((uap->shmflg & IPC_CREAT) == 0)
			return (ENOENT);
		if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
			return (EINVAL);
		for (i = 0; i < shminfo.shmmni; i++)
			if ((shmsegs[i].shm_perm.mode & SHM_ALLOC) == 0) {
				rval = i;
				break;
			}
		if (i == shminfo.shmmni)
			return (ENOSPC);
		size = clrnd(btoc(uap->size));
		if (shmtot + size > shminfo.shmall)
			return (ENOMEM);
		shp = &shmsegs[rval];
		/*
		 * We need to do a couple of things to ensure consistency
		 * in case we sleep in malloc().  We mark segment as
		 * allocated so that other shmgets() will not allocate it.
		 * We mark it as "destroyed" to insure that shmvalid() is
		 * false making most operations fail (XXX).  We set the key,
		 * so that other shmget()s will fail.
		 */
		shp->shm_perm.mode = SHM_ALLOC | SHM_DEST;
		shp->shm_perm.key = uap->key;
		kva = (caddr_t) malloc((u_long)ctob(size), M_SHM, M_WAITOK);
		if (kva == NULL) {
			shp->shm_perm.mode = 0;
			return (ENOMEM);
		}
		if (!claligned(kva))
			panic("shmget: non-aligned memory");
		bzero(kva, (u_int)ctob(size));
		shmtot += size;
		shp->shm_perm.cuid = shp->shm_perm.uid = cred->cr_uid;
		shp->shm_perm.cgid = shp->shm_perm.gid = cred->cr_gid;
		shp->shm_perm.mode = SHM_ALLOC | (uap->shmflg&0777);
		shp->shm_handle = (void *) kvtopte(kva);
		shp->shm_segsz = uap->size;
		shp->shm_cpid = p->p_pid;
		shp->shm_lpid = shp->shm_nattch = 0;
		shp->shm_atime = shp->shm_dtime = 0;
		shp->shm_ctime = time.tv_sec;
	} else {
		shp = &shmsegs[rval];
		/* XXX: probably not the right thing to do */
		if (shp->shm_perm.mode & SHM_DEST)
			return (EBUSY);
		if (error = ipcaccess(&shp->shm_perm, uap->shmflg&0777, cred))
			return (error);
		if (uap->size && uap->size > shp->shm_segsz)
			return (EINVAL);
		if ((uap->shmflg&IPC_CREAT) && (uap->shmflg&IPC_EXCL))
			return (EEXIST);
	}
	*retval = shp->shm_perm.seq * SHMMMNI + rval;
	return (0);
}

/*
 * Shared memory control
 */
/* ARGSUSED */
shmctl(p, uap, retval)
	struct proc *p;
	register struct args {
		int shmid;
		int cmd;
		caddr_t buf;
	} *uap;
	int *retval;
{
	register struct shmid_ds *shp;
	register struct ucred *cred = u.u_cred;
	struct shmid_ds sbuf;
	int error;

	if (error = shmvalid(uap->shmid))
		return (error);
	shp = &shmsegs[uap->shmid % SHMMMNI];
	switch (uap->cmd) {
	case IPC_STAT:
		if (error = ipcaccess(&shp->shm_perm, IPC_R, cred))
			return (error);
		return (copyout((caddr_t)shp, uap->buf, sizeof(*shp)));

	case IPC_SET:
		if (cred->cr_uid && cred->cr_uid != shp->shm_perm.uid &&
		    cred->cr_uid != shp->shm_perm.cuid)
			return (EPERM);
		if (error = copyin(uap->buf, (caddr_t)&sbuf, sizeof sbuf))
			return (error);
		shp->shm_perm.uid = sbuf.shm_perm.uid;
		shp->shm_perm.gid = sbuf.shm_perm.gid;
		shp->shm_perm.mode = (shp->shm_perm.mode & ~0777)
			| (sbuf.shm_perm.mode & 0777);
		shp->shm_ctime = time.tv_sec;
		break;

	case IPC_RMID:
		if (cred->cr_uid && cred->cr_uid != shp->shm_perm.uid &&
		    cred->cr_uid != shp->shm_perm.cuid)
			return (EPERM);
		/* set ctime? */
		shp->shm_perm.key = IPC_PRIVATE;
		shp->shm_perm.mode |= SHM_DEST;
		if (shp->shm_nattch <= 0)
			shmfree(shp);
		break;

#ifdef HPUXCOMPAT
	case SHM_LOCK:
	case SHM_UNLOCK:
		/* don't really do anything, but make them think we did */
		if ((p->p_flag & SHPUX) == 0)
			return (EINVAL);
		if (cred->cr_uid && cred->cr_uid != shp->shm_perm.uid &&
		    cred->cr_uid != shp->shm_perm.cuid)
			return (EPERM);
		break;
#endif

	default:
		return (EINVAL);
	}
	return (0);
}

/*
 * Attach to shared memory segment.
 */
shmat(p, uap, retval)
	struct proc *p;
	register struct args {
		int	shmid;
		caddr_t	shmaddr;
		int	shmflg;
	} *uap;
	int *retval;
{
	register struct shmid_ds *shp;
	register int size;
	struct mapmem *mp;
	caddr_t uva;
	int error, prot, shmmapin();

	if (error = shmvalid(uap->shmid))
		return (error);
	shp = &shmsegs[uap->shmid % SHMMMNI];
	if (shp->shm_handle == NULL)
		panic("shmat NULL handle");
	if (error = ipcaccess(&shp->shm_perm,
			(uap->shmflg&SHM_RDONLY) ? IPC_R : IPC_R|IPC_W, u.u_cred))
		return (error);
	uva = uap->shmaddr;
	if (uva && ((int)uva & (SHMLBA-1))) {
		if (uap->shmflg & SHM_RND)
			uva = (caddr_t) ((int)uva & ~(SHMLBA-1));
		else
			return (EINVAL);
	}
	/*
	 * Make sure user doesn't use more than their fair share
	 */
	size = 0;
	for (mp = u.u_mmap; mp; mp = mp->mm_next)
		if (mp->mm_ops == &shmops)
			size++;
	if (size >= shminfo.shmseg)
		return (EMFILE);
	/*
	 * Allocate a mapped memory region descriptor and
	 * attempt to expand the user page table to allow for region
	 */
	prot = (uap->shmflg & SHM_RDONLY) ? MM_RO : MM_RW;
#if defined(hp300)
	prot |= MM_CI;
#endif
	size = ctob(clrnd(btoc(shp->shm_segsz)));
	error = mmalloc(p, uap->shmid, &uva, (segsz_t)size, prot, &shmops, &mp);
	if (error)
		return (error);
	if (error = mmmapin(p, mp, shmmapin)) {
		(void) mmfree(p, mp);
		return (error);
	}
	/*
	 * Fill in the remaining fields
	 */
	shp->shm_lpid = p->p_pid;
	shp->shm_atime = time.tv_sec;
	shp->shm_nattch++;
	*retval = (int) uva;
	return (0);
}

/*
 * Detach from shared memory segment.
 */
/* ARGSUSED */
shmdt(p, uap, retval)
	struct proc *p;
	struct args {
		caddr_t	shmaddr;
	} *uap;
	int *retval;
{
	register struct mapmem *mp;

	for (mp = u.u_mmap; mp; mp = mp->mm_next)
		if (mp->mm_ops == &shmops && mp->mm_uva == uap->shmaddr)
			break;
	if (mp == MMNIL)
		return (EINVAL);
	shmsegs[mp->mm_id % SHMMMNI].shm_lpid = p->p_pid;
	return (shmufree(p, mp));
}

shmmapin(mp, off)
	struct mapmem *mp;
{
	register struct shmid_ds *shp;

	shp = &shmsegs[mp->mm_id % SHMMMNI];
	if (off >= ctob(clrnd(btoc(shp->shm_segsz))))
		return(-1);
	return(((struct pte *)shp->shm_handle)[btop(off)].pg_pfnum);
}

/*
 * Increment attach count on fork
 */
/* ARGSUSED */
shmfork(mp, ischild)
	register struct mapmem *mp;
{
	if (!ischild)
		shmsegs[mp->mm_id % SHMMMNI].shm_nattch++;
}

/*
 * Detach from shared memory segment on exit (or exec)
 */
shmexit(mp)
	struct mapmem *mp;
{
	struct proc *p = u.u_procp;		/* XXX */

	return (shmufree(p, mp));
}

shmvalid(id)
	register int id;
{
	register struct shmid_ds *shp;

	if (id < 0 || (id % SHMMMNI) >= shminfo.shmmni)
		return(EINVAL);
	shp = &shmsegs[id % SHMMMNI];
	if (shp->shm_perm.seq == (id / SHMMMNI) &&
	    (shp->shm_perm.mode & (SHM_ALLOC|SHM_DEST)) == SHM_ALLOC)
		return(0);
	return(EINVAL);
}

/*
 * Free user resources associated with a shared memory segment
 */
shmufree(p, mp)
	struct proc *p;
	struct mapmem *mp;
{
	register struct shmid_ds *shp;
	int error;

	shp = &shmsegs[mp->mm_id % SHMMMNI];
	mmmapout(p, mp);
	error = mmfree(p, mp);
	shp->shm_dtime = time.tv_sec;
	if (--shp->shm_nattch <= 0 && (shp->shm_perm.mode & SHM_DEST))
		shmfree(shp);
	return (error);
}

/*
 * Deallocate resources associated with a shared memory segment
 */
shmfree(shp)
	register struct shmid_ds *shp;
{
	caddr_t kva;

	if (shp->shm_handle == NULL)
		panic("shmfree");
	kva = (caddr_t) ptetokv(shp->shm_handle);
	free(kva, M_SHM);
	shp->shm_handle = NULL;
	shmtot -= clrnd(btoc(shp->shm_segsz));
	shp->shm_perm.mode = 0;
	/*
	 * Increment the sequence number to ensure that outstanding
	 * shmids for this segment will be invalid in the event that
	 * the segment is reallocated.  Note that shmids must be
	 * positive as decreed by SVID.
	 */
	shp->shm_perm.seq++;
	if ((int)(shp->shm_perm.seq * SHMMMNI) < 0)
		shp->shm_perm.seq = 0;
}

/*
 * XXX This routine would be common to all sysV style IPC
 *     (if the others were implemented).
 */
ipcaccess(ipc, mode, cred)
	register struct ipc_perm *ipc;
	int mode;
	register struct ucred *cred;
{
	register int m;

	if (cred->cr_uid == 0)
		return(0);
	/*
	 * Access check is based on only one of owner, group, public.
	 * If not owner, then check group.
	 * If not a member of the group, then check public access.
	 */
	mode &= 0700;
	m = ipc->mode;
	if (cred->cr_uid != ipc->uid && cred->cr_uid != ipc->cuid) {
		m <<= 3;
		if (!groupmember(ipc->gid, cred) &&
		    !groupmember(ipc->cgid, cred))
			m <<= 3;
	}
	if ((mode&m) == mode)
		return (0);
	return (EACCES);
}

#endif /* SYSVSHM */
Commit	Line	Data
	1	/*
	2	* Copyright (c) 1988 University of Utah.
	3	* Copyright (c) 1990 The Regents of the University of California.
	4	* All rights reserved.
	5	*
	6	* This code is derived from software contributed to Berkeley by
	7	* the Systems Programming Group of the University of Utah Computer
	8	* Science Department. Originally from University of Wisconsin.
	9	*
	10	* %sccs.include.redist.c%
	11	*
	12	* from: Utah $Hdr: uipc_shm.c 1.9 89/08/14$
	13	*
	14	* @(#)sysv_shm.c 7.8 (Berkeley) %G%
	15	*/
	16
	17	/*
	18	* System V shared memory routines.
	19	* TEMPORARY, until mmap is in place;
	20	* needed now for HP-UX compatibility and X server (yech!).
	21	*/
	22
	23	#ifdef SYSVSHM
	24
	25	#include "machine/pte.h"
	26
	27	#include "param.h"
	28	#include "systm.h"
	29	#include "syscontext.h"
	30	#include "kernel.h"
	31	#include "proc.h"
	32	#include "vm.h"
	33	#include "shm.h"
	34	#include "mapmem.h"
	35	#include "malloc.h"
	36
	37	#ifdef HPUXCOMPAT
	38	#include "../hpux/hpux.h"
	39	#endif
	40
	41	int shmat(), shmctl(), shmdt(), shmget();
	42	int (*shmcalls[])() = { shmat, shmctl, shmdt, shmget };
	43	int shmtot = 0;
	44
	45	int shmfork(), shmexit();
	46	struct mapmemops shmops = { shmfork, (int (*)())0, shmexit, shmexit };
	47
	48	shminit()
	49	{
	50	register int i;
	51
	52	if (shminfo.shmmni > SHMMMNI)
	53	shminfo.shmmni = SHMMMNI;
	54	for (i = 0; i < shminfo.shmmni; i++) {
	55	shmsegs[i].shm_perm.mode = 0;
	56	shmsegs[i].shm_perm.seq = 0;
	57	}
	58	}
	59
	60	/*
	61	* Entry point for all SHM calls
	62	*/
	63	shmsys(p, uap, retval)
	64	struct proc *p;
	65	struct args {
	66	u_int which;
	67	} *uap;
	68	int *retval;
	69	{
	70
	71	if (uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0]))
	72	RETURN (EINVAL);
	73	RETURN ((*shmcalls[uap->which])(p, &uap[1], retval));
	74	}
	75
	76	/*
	77	* Get a shared memory segment
	78	*/
	79	shmget(p, uap, retval)
	80	struct proc *p;
	81	register struct args {
	82	key_t key;
	83	int size;
	84	int shmflg;
	85	} *uap;
	86	int *retval;
	87	{
	88	register struct shmid_ds *shp;
	89	register struct ucred *cred = u.u_cred;
	90	register int i;
	91	int error, size, rval = 0;
	92	caddr_t kva;
	93
	94	/* look up the specified shm_id */
	95	if (uap->key != IPC_PRIVATE) {
	96	for (i = 0; i < shminfo.shmmni; i++)
	97	if ((shmsegs[i].shm_perm.mode & SHM_ALLOC) &&
	98	shmsegs[i].shm_perm.key == uap->key) {
	99	rval = i;
	100	break;
	101	}
	102	} else
	103	i = shminfo.shmmni;
	104
	105	/* create a new shared segment if necessary */
	106	if (i == shminfo.shmmni) {
	107	if ((uap->shmflg & IPC_CREAT) == 0)
	108	return (ENOENT);
	109	if (uap->size < shminfo.shmmin \|\| uap->size > shminfo.shmmax)
	110	return (EINVAL);
	111	for (i = 0; i < shminfo.shmmni; i++)
	112	if ((shmsegs[i].shm_perm.mode & SHM_ALLOC) == 0) {
	113	rval = i;
	114	break;
	115	}
	116	if (i == shminfo.shmmni)
	117	return (ENOSPC);
	118	size = clrnd(btoc(uap->size));
	119	if (shmtot + size > shminfo.shmall)
	120	return (ENOMEM);
	121	shp = &shmsegs[rval];
	122	/*
	123	* We need to do a couple of things to ensure consistency
	124	* in case we sleep in malloc(). We mark segment as
	125	* allocated so that other shmgets() will not allocate it.
	126	* We mark it as "destroyed" to insure that shmvalid() is
	127	* false making most operations fail (XXX). We set the key,
	128	* so that other shmget()s will fail.
	129	*/
	130	shp->shm_perm.mode = SHM_ALLOC \| SHM_DEST;
	131	shp->shm_perm.key = uap->key;
	132	kva = (caddr_t) malloc((u_long)ctob(size), M_SHM, M_WAITOK);
	133	if (kva == NULL) {
	134	shp->shm_perm.mode = 0;
	135	return (ENOMEM);
	136	}
	137	if (!claligned(kva))
	138	panic("shmget: non-aligned memory");
	139	bzero(kva, (u_int)ctob(size));
	140	shmtot += size;
	141	shp->shm_perm.cuid = shp->shm_perm.uid = cred->cr_uid;
	142	shp->shm_perm.cgid = shp->shm_perm.gid = cred->cr_gid;
	143	shp->shm_perm.mode = SHM_ALLOC \| (uap->shmflg&0777);
	144	shp->shm_handle = (void *) kvtopte(kva);
	145	shp->shm_segsz = uap->size;
	146	shp->shm_cpid = p->p_pid;
	147	shp->shm_lpid = shp->shm_nattch = 0;
	148	shp->shm_atime = shp->shm_dtime = 0;
	149	shp->shm_ctime = time.tv_sec;
	150	} else {
	151	shp = &shmsegs[rval];
	152	/* XXX: probably not the right thing to do */
	153	if (shp->shm_perm.mode & SHM_DEST)
	154	return (EBUSY);
	155	if (error = ipcaccess(&shp->shm_perm, uap->shmflg&0777, cred))
	156	return (error);
	157	if (uap->size && uap->size > shp->shm_segsz)
	158	return (EINVAL);
	159	if ((uap->shmflg&IPC_CREAT) && (uap->shmflg&IPC_EXCL))
	160	return (EEXIST);
	161	}
	162	retval = shp->shm_perm.seq SHMMMNI + rval;
	163	return (0);
	164	}
	165
	166	/*
	167	* Shared memory control
	168	*/
	169	/* ARGSUSED */
	170	shmctl(p, uap, retval)
	171	struct proc *p;
	172	register struct args {
	173	int shmid;
	174	int cmd;
	175	caddr_t buf;
	176	} *uap;
	177	int *retval;
	178	{
	179	register struct shmid_ds *shp;
	180	register struct ucred *cred = u.u_cred;
	181	struct shmid_ds sbuf;
	182	int error;
	183
	184	if (error = shmvalid(uap->shmid))
	185	return (error);
	186	shp = &shmsegs[uap->shmid % SHMMMNI];
	187	switch (uap->cmd) {
	188	case IPC_STAT:
	189	if (error = ipcaccess(&shp->shm_perm, IPC_R, cred))
	190	return (error);
	191	return (copyout((caddr_t)shp, uap->buf, sizeof(*shp)));
	192
	193	case IPC_SET:
	194	if (cred->cr_uid && cred->cr_uid != shp->shm_perm.uid &&
	195	cred->cr_uid != shp->shm_perm.cuid)
	196	return (EPERM);
	197	if (error = copyin(uap->buf, (caddr_t)&sbuf, sizeof sbuf))
	198	return (error);
	199	shp->shm_perm.uid = sbuf.shm_perm.uid;
	200	shp->shm_perm.gid = sbuf.shm_perm.gid;
	201	shp->shm_perm.mode = (shp->shm_perm.mode & ~0777)
	202	\| (sbuf.shm_perm.mode & 0777);
	203	shp->shm_ctime = time.tv_sec;
	204	break;
	205
	206	case IPC_RMID:
	207	if (cred->cr_uid && cred->cr_uid != shp->shm_perm.uid &&
	208	cred->cr_uid != shp->shm_perm.cuid)
	209	return (EPERM);
	210	/* set ctime? */
	211	shp->shm_perm.key = IPC_PRIVATE;
	212	shp->shm_perm.mode \|= SHM_DEST;
	213	if (shp->shm_nattch <= 0)
	214	shmfree(shp);
	215	break;
	216
	217	#ifdef HPUXCOMPAT
	218	case SHM_LOCK:
	219	case SHM_UNLOCK:
	220	/* don't really do anything, but make them think we did */
	221	if ((p->p_flag & SHPUX) == 0)
	222	return (EINVAL);
	223	if (cred->cr_uid && cred->cr_uid != shp->shm_perm.uid &&
	224	cred->cr_uid != shp->shm_perm.cuid)
	225	return (EPERM);
	226	break;
	227	#endif
	228
	229	default:
	230	return (EINVAL);
	231	}
	232	return (0);
	233	}
	234
	235	/*
	236	* Attach to shared memory segment.
	237	*/
	238	shmat(p, uap, retval)
	239	struct proc *p;
	240	register struct args {
	241	int shmid;
	242	caddr_t shmaddr;
	243	int shmflg;
	244	} *uap;
	245	int *retval;
	246	{
	247	register struct shmid_ds *shp;
	248	register int size;
	249	struct mapmem *mp;
	250	caddr_t uva;
	251	int error, prot, shmmapin();
	252
	253	if (error = shmvalid(uap->shmid))
	254	return (error);
	255	shp = &shmsegs[uap->shmid % SHMMMNI];
	256	if (shp->shm_handle == NULL)
	257	panic("shmat NULL handle");
	258	if (error = ipcaccess(&shp->shm_perm,
	259	(uap->shmflg&SHM_RDONLY) ? IPC_R : IPC_R\|IPC_W, u.u_cred))
	260	return (error);
	261	uva = uap->shmaddr;
	262	if (uva && ((int)uva & (SHMLBA-1))) {
	263	if (uap->shmflg & SHM_RND)
	264	uva = (caddr_t) ((int)uva & ~(SHMLBA-1));
	265	else
	266	return (EINVAL);
	267	}
	268	/*
	269	* Make sure user doesn't use more than their fair share
	270	*/
	271	size = 0;
	272	for (mp = u.u_mmap; mp; mp = mp->mm_next)
	273	if (mp->mm_ops == &shmops)
	274	size++;
	275	if (size >= shminfo.shmseg)
	276	return (EMFILE);
	277	/*
	278	* Allocate a mapped memory region descriptor and
	279	* attempt to expand the user page table to allow for region
	280	*/
	281	prot = (uap->shmflg & SHM_RDONLY) ? MM_RO : MM_RW;
	282	#if defined(hp300)
	283	prot \|= MM_CI;
	284	#endif
	285	size = ctob(clrnd(btoc(shp->shm_segsz)));
	286	error = mmalloc(p, uap->shmid, &uva, (segsz_t)size, prot, &shmops, &mp);
	287	if (error)
	288	return (error);
	289	if (error = mmmapin(p, mp, shmmapin)) {
	290	(void) mmfree(p, mp);
	291	return (error);
	292	}
	293	/*
	294	* Fill in the remaining fields
	295	*/
	296	shp->shm_lpid = p->p_pid;
	297	shp->shm_atime = time.tv_sec;
	298	shp->shm_nattch++;
	299	*retval = (int) uva;
	300	return (0);
	301	}
	302
	303	/*
	304	* Detach from shared memory segment.
	305	*/
	306	/* ARGSUSED */
	307	shmdt(p, uap, retval)
	308	struct proc *p;
	309	struct args {
	310	caddr_t shmaddr;
	311	} *uap;
	312	int *retval;
	313	{
	314	register struct mapmem *mp;
	315
	316	for (mp = u.u_mmap; mp; mp = mp->mm_next)
	317	if (mp->mm_ops == &shmops && mp->mm_uva == uap->shmaddr)
	318	break;
	319	if (mp == MMNIL)
	320	return (EINVAL);
	321	shmsegs[mp->mm_id % SHMMMNI].shm_lpid = p->p_pid;
	322	return (shmufree(p, mp));
	323	}
	324
	325	shmmapin(mp, off)
	326	struct mapmem *mp;
	327	{
	328	register struct shmid_ds *shp;
	329
	330	shp = &shmsegs[mp->mm_id % SHMMMNI];
	331	if (off >= ctob(clrnd(btoc(shp->shm_segsz))))
	332	return(-1);
	333	return(((struct pte *)shp->shm_handle)[btop(off)].pg_pfnum);
	334	}
	335
	336	/*
	337	* Increment attach count on fork
	338	*/
	339	/* ARGSUSED */
	340	shmfork(mp, ischild)
	341	register struct mapmem *mp;
	342	{
	343	if (!ischild)
	344	shmsegs[mp->mm_id % SHMMMNI].shm_nattch++;
	345	}
	346
	347	/*
	348	* Detach from shared memory segment on exit (or exec)
	349	*/
	350	shmexit(mp)
	351	struct mapmem *mp;
	352	{
	353	struct proc p = u.u_procp; / XXX */
	354
	355	return (shmufree(p, mp));
	356	}
	357
	358	shmvalid(id)
	359	register int id;
	360	{
	361	register struct shmid_ds *shp;
	362
	363	if (id < 0 \|\| (id % SHMMMNI) >= shminfo.shmmni)
	364	return(EINVAL);
	365	shp = &shmsegs[id % SHMMMNI];
	366	if (shp->shm_perm.seq == (id / SHMMMNI) &&
	367	(shp->shm_perm.mode & (SHM_ALLOC\|SHM_DEST)) == SHM_ALLOC)
	368	return(0);
	369	return(EINVAL);
	370	}
	371
	372	/*
	373	* Free user resources associated with a shared memory segment
	374	*/
	375	shmufree(p, mp)
	376	struct proc *p;
	377	struct mapmem *mp;
	378	{
	379	register struct shmid_ds *shp;
	380	int error;
	381
	382	shp = &shmsegs[mp->mm_id % SHMMMNI];
	383	mmmapout(p, mp);
	384	error = mmfree(p, mp);
	385	shp->shm_dtime = time.tv_sec;
	386	if (--shp->shm_nattch <= 0 && (shp->shm_perm.mode & SHM_DEST))
	387	shmfree(shp);
	388	return (error);
	389	}
	390
	391	/*
	392	* Deallocate resources associated with a shared memory segment
	393	*/
	394	shmfree(shp)
	395	register struct shmid_ds *shp;
	396	{
	397	caddr_t kva;
	398
	399	if (shp->shm_handle == NULL)
	400	panic("shmfree");
	401	kva = (caddr_t) ptetokv(shp->shm_handle);
	402	free(kva, M_SHM);
	403	shp->shm_handle = NULL;
	404	shmtot -= clrnd(btoc(shp->shm_segsz));
	405	shp->shm_perm.mode = 0;
	406	/*
	407	* Increment the sequence number to ensure that outstanding
	408	* shmids for this segment will be invalid in the event that
	409	* the segment is reallocated. Note that shmids must be
	410	* positive as decreed by SVID.
	411	*/
	412	shp->shm_perm.seq++;
	413	if ((int)(shp->shm_perm.seq * SHMMMNI) < 0)
	414	shp->shm_perm.seq = 0;
	415	}
	416
	417	/*
	418	* XXX This routine would be common to all sysV style IPC
	419	* (if the others were implemented).
	420	*/
	421	ipcaccess(ipc, mode, cred)
	422	register struct ipc_perm *ipc;
	423	int mode;
	424	register struct ucred *cred;
	425	{
	426	register int m;
	427
	428	if (cred->cr_uid == 0)
	429	return(0);
	430	/*
	431	* Access check is based on only one of owner, group, public.
	432	* If not owner, then check group.
	433	* If not a member of the group, then check public access.
	434	*/
	435	mode &= 0700;
	436	m = ipc->mode;
	437	if (cred->cr_uid != ipc->uid && cred->cr_uid != ipc->cuid) {
	438	m <<= 3;
	439	if (!groupmember(ipc->gid, cred) &&
	440	!groupmember(ipc->cgid, cred))
	441	m <<= 3;
	442	}
	443	if ((mode&m) == mode)
	444	return (0);
	445	return (EACCES);
	446	}
	447
	448	#endif /* SYSVSHM */