[unix-history] / 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	7.2 (Berkeley) %G%
 */

/*
 * System V shared memory routines.
 */

#ifdef SYSVSHM

#include "machine/pte.h"

#include "param.h"
#include "systm.h"
#include "user.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()
{
	struct a {
		int which;
	} *uap = (struct a *)u.u_ap;

	if (uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0])) {
		u.u_error = EINVAL;
		return;
	}
	(*shmcalls[uap->which])(u.u_ap+1);
}

/* get a shared memory segment */
shmget(ap)
	int *ap;
{
	register struct a {
		key_t key;
		int size;
		int shmflg;
	} *uap = (struct a *)ap;
	register struct shmid_ds *shp;
	register int i;
	int rval = 0, size;
	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) {
			u.u_error = ENOENT;
			return;
		}
		if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax) {
			u.u_error = EINVAL;
			return;
		}
		for (i = 0; i < shminfo.shmmni; i++)
			if ((shmsegs[i].shm_perm.mode & SHM_ALLOC) == 0) {
				rval = i;
				break;
			}
		if (i == shminfo.shmmni) {
			u.u_error = ENOSPC;
			return;
		}
		size = clrnd(btoc(uap->size));
		if (shmtot + size > shminfo.shmall) {
			u.u_error = ENOMEM;
			return;
		}
		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;
			u.u_error = ENOMEM;
			return;
		}
		if (!claligned(kva))
			panic("shmget: non-aligned memory");
		bzero(kva, (u_int)ctob(size));
		shmtot += size;
		shp->shm_perm.cuid = shp->shm_perm.uid = u.u_uid;
		shp->shm_perm.cgid = shp->shm_perm.gid = u.u_gid;
		shp->shm_perm.mode = SHM_ALLOC | (uap->shmflg&0777);
		shp->shm_handle = (void *) kvtopte(kva);
		shp->shm_segsz = uap->size;
		shp->shm_cpid = u.u_procp->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) {
			u.u_error = EBUSY;
			return;
		}
		if (!ipcaccess(&shp->shm_perm, uap->shmflg&0777))
			return;
		if (uap->size && uap->size > shp->shm_segsz) {
			u.u_error = EINVAL;
			return;
		}
		if ((uap->shmflg&IPC_CREAT) && (uap->shmflg&IPC_EXCL)) {
			u.u_error = EEXIST;
			return;
		}
	}
	u.u_r.r_val1 = shp->shm_perm.seq * SHMMMNI + rval;
}

/* shared memory control */
shmctl(ap)
	int *ap;
{
	register struct a {
		int shmid;
		int cmd;
		caddr_t buf;
	} *uap = (struct a *)ap;
	register struct shmid_ds *shp;
	struct shmid_ds sbuf;

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

	case IPC_SET:
		if (u.u_uid && u.u_uid != shp->shm_perm.uid &&
		    u.u_uid != shp->shm_perm.cuid) {
			u.u_error = EPERM;
			break;
		}
		u.u_error = copyin(uap->buf, (caddr_t)&sbuf, sizeof sbuf);
		if (!u.u_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 (u.u_uid && u.u_uid != shp->shm_perm.uid &&
		    u.u_uid != shp->shm_perm.cuid) {
			u.u_error = EPERM;
			break;
		}
		/* 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 ((u.u_procp->p_flag & SHPUX) == 0)
			u.u_error = EINVAL;
		else if (u.u_uid && u.u_uid != shp->shm_perm.uid &&
			 u.u_uid != shp->shm_perm.cuid)
			u.u_error = EPERM;
		break;
#endif

	default:
		u.u_error = EINVAL;
		break;
	}
}

shmat(ap)
	int *ap;
{
	struct a {
		int	shmid;
		caddr_t	shmaddr;
		int	shmflg;
	} *uap = (struct a *)ap;
	register struct shmid_ds *shp;
	register int size;
	struct mapmem *mp;
	caddr_t uva;
	int prot, shmmapin();

	if (!shmvalid(uap->shmid))
		return;
	shp = &shmsegs[uap->shmid % SHMMMNI];
	if (shp->shm_handle == NULL)
		panic("shmat NULL ptbl");
	if (!ipcaccess(&shp->shm_perm,
		      (uap->shmflg&SHM_RDONLY) ? IPC_R : IPC_R|IPC_W))
		return;
	uva = uap->shmaddr;
	if (uva && ((int)uva & (SHMLBA-1))) {
		if (uap->shmflg & SHM_RND)
			uva = (caddr_t) ((int)uva & ~(SHMLBA-1));
		else {
			u.u_error = EINVAL;
			return;
		}
	}
	/*
	 * 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) {
		u.u_error = EMFILE;
		return;
	}
	/*
	 * 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)));
	mp = mmalloc(uap->shmid, &uva, (segsz_t)size, prot, &shmops);
	if (mp == MMNIL)
		return;
	if (!mmmapin(mp, shmmapin)) {
		mmfree(mp);
		return;
	}
	/*
	 * Fill in the remaining fields
	 */
	shp->shm_lpid = u.u_procp->p_pid;
	shp->shm_atime = time.tv_sec;
	shp->shm_nattch++;
	u.u_r.r_val1 = (int) uva;
}

shmdt(ap)
	int *ap;
{
	register struct a {
		caddr_t	shmaddr;
	} *uap = (struct a *)ap;
	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) {
		u.u_error = EINVAL;
		return;
	}
	shmsegs[mp->mm_id % SHMMMNI].shm_lpid = u.u_procp->p_pid;
	shmufree(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
 */
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)
	register struct mapmem *mp;
{
	shmufree(mp);
}

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

	if (id < 0 || (id % SHMMMNI) >= shminfo.shmmni)
		return(0);
	shp = &shmsegs[id % SHMMMNI];
	if (shp->shm_perm.seq == (id / SHMMMNI) &&
	    (shp->shm_perm.mode & (SHM_ALLOC|SHM_DEST)) == SHM_ALLOC)
		return(1);
	u.u_error = EINVAL;
	return(0);
}

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

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

/*
 * 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)
	register struct ipc_perm *ipc;
{
	register int m;

	if (u.u_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 (u.u_uid != ipc->uid && u.u_uid != ipc->cuid) {
		m <<= 3;
		if (!groupmember(ipc->gid, u.u_cred) &&
		    !groupmember(ipc->cgid, u.u_cred))
			m <<= 3;
	}
	if ((mode&m) == mode)
		return (1);
	u.u_error = EACCES;
	return (0);
}

#endif /* SYSVSHM */
Commit	Line	Data
6f843dc9 KM	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	*
e5b27ef1	14	* @(#)sysv_shm.c 7.2 (Berkeley) %G%
6f843dc9 KM	15	*/
	16
	17	/*
	18	* System V shared memory routines.
	19	*/
	20
	21	#ifdef SYSVSHM
	22
	23	#include "machine/pte.h"
	24
	25	#include "param.h"
	26	#include "systm.h"
	27	#include "user.h"
	28	#include "kernel.h"
	29	#include "proc.h"
	30	#include "vm.h"
	31	#include "shm.h"
	32	#include "mapmem.h"
	33	#include "malloc.h"
	34
	35	#ifdef HPUXCOMPAT
	36	#include "../hpux/hpux.h"
	37	#endif
	38
	39	int shmat(), shmctl(), shmdt(), shmget();
	40	int (*shmcalls[])() = { shmat, shmctl, shmdt, shmget };
	41	int shmtot = 0;
	42
	43	int shmfork(), shmexit();
	44	struct mapmemops shmops = { shmfork, (int (*)())0, shmexit, shmexit };
	45
	46	shminit()
	47	{
	48	register int i;
	49
	50	if (shminfo.shmmni > SHMMMNI)
	51	shminfo.shmmni = SHMMMNI;
	52	for (i = 0; i < shminfo.shmmni; i++) {
	53	shmsegs[i].shm_perm.mode = 0;
	54	shmsegs[i].shm_perm.seq = 0;
	55	}
	56	}
	57
	58	/* entry point for all SHM calls */
	59	shmsys()
	60	{
	61	struct a {
	62	int which;
	63	} uap = (struct a )u.u_ap;
	64
	65	if (uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0])) {
	66	u.u_error = EINVAL;
	67	return;
	68	}
	69	(*shmcalls[uap->which])(u.u_ap+1);
	70	}
	71
	72	/* get a shared memory segment */
	73	shmget(ap)
	74	int *ap;
	75	{
	76	register struct a {
	77	key_t key;
	78	int size;
79	int shmflg;
80	} uap = (struct a )ap;
81	register struct shmid_ds *shp;
82	register int i;
83	int rval = 0, size;
84	caddr_t kva;
85
86	/* look up the specified shm_id */
87	if (uap->key != IPC_PRIVATE) {
88	for (i = 0; i < shminfo.shmmni; i++)
89	if ((shmsegs[i].shm_perm.mode & SHM_ALLOC) &&
90	shmsegs[i].shm_perm.key == uap->key) {
91	rval = i;
92	break;
93	}
94	} else
95	i = shminfo.shmmni;
96
97	/* create a new shared segment if necessary */
98	if (i == shminfo.shmmni) {
99	if ((uap->shmflg & IPC_CREAT) == 0) {
100	u.u_error = ENOENT;
101	return;
102	}
103	if (uap->size < shminfo.shmmin \|\| uap->size > shminfo.shmmax) {
104	u.u_error = EINVAL;
105	return;
106	}
107	for (i = 0; i < shminfo.shmmni; i++)
108	if ((shmsegs[i].shm_perm.mode & SHM_ALLOC) == 0) {
109	rval = i;
110	break;
111	}
112	if (i == shminfo.shmmni) {
113	u.u_error = ENOSPC;
114	return;
115	}
116	size = clrnd(btoc(uap->size));
117	if (shmtot + size > shminfo.shmall) {
118	u.u_error = ENOMEM;
119	return;
120	}
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	u.u_error = ENOMEM;
136	return;
137	}
138	if (!claligned(kva))
139	panic("shmget: non-aligned memory");
140	bzero(kva, (u_int)ctob(size));
141	shmtot += size;
142	shp->shm_perm.cuid = shp->shm_perm.uid = u.u_uid;
143	shp->shm_perm.cgid = shp->shm_perm.gid = u.u_gid;
144	shp->shm_perm.mode = SHM_ALLOC \| (uap->shmflg&0777);
145	shp->shm_handle = (void *) kvtopte(kva);
146	shp->shm_segsz = uap->size;
147	shp->shm_cpid = u.u_procp->p_pid;
148	shp->shm_lpid = shp->shm_nattch = 0;
149	shp->shm_atime = shp->shm_dtime = 0;
150	shp->shm_ctime = time.tv_sec;
151	} else {
152	shp = &shmsegs[rval];
153	/* XXX: probably not the right thing to do */
154	if (shp->shm_perm.mode & SHM_DEST) {
155	u.u_error = EBUSY;
156	return;
157	}
158	if (!ipcaccess(&shp->shm_perm, uap->shmflg&0777))
159	return;
160	if (uap->size && uap->size > shp->shm_segsz) {
161	u.u_error = EINVAL;
162	return;
163	}
164	if ((uap->shmflg&IPC_CREAT) && (uap->shmflg&IPC_EXCL)) {
165	u.u_error = EEXIST;
166	return;
167	}
168	}
169	u.u_r.r_val1 = shp->shm_perm.seq * SHMMMNI + rval;
170	}
171
172	/* shared memory control */
173	shmctl(ap)
174	int *ap;
175	{
176	register struct a {
177	int shmid;
178	int cmd;
179	caddr_t buf;
180	} uap = (struct a )ap;
181	register struct shmid_ds *shp;
182	struct shmid_ds sbuf;
183
184	if (!shmvalid(uap->shmid))
185	return;
186	shp = &shmsegs[uap->shmid % SHMMMNI];
187	switch (uap->cmd) {
188	case IPC_STAT:
189	if (ipcaccess(&shp->shm_perm, IPC_R))
190	u.u_error =
191	copyout((caddr_t)shp, uap->buf, sizeof(*shp));
192	break;
193
194	case IPC_SET:
195	if (u.u_uid && u.u_uid != shp->shm_perm.uid &&
196	u.u_uid != shp->shm_perm.cuid) {
197	u.u_error = EPERM;
198	break;
199	}
200	u.u_error = copyin(uap->buf, (caddr_t)&sbuf, sizeof sbuf);
201	if (!u.u_error) {
202	shp->shm_perm.uid = sbuf.shm_perm.uid;
203	shp->shm_perm.gid = sbuf.shm_perm.gid;
204	shp->shm_perm.mode = (shp->shm_perm.mode & ~0777)
205	\| (sbuf.shm_perm.mode & 0777);
206	shp->shm_ctime = time.tv_sec;
207	}
208	break;
209
210	case IPC_RMID:
211	if (u.u_uid && u.u_uid != shp->shm_perm.uid &&
212	u.u_uid != shp->shm_perm.cuid) {
213	u.u_error = EPERM;
214	break;
215	}
216	/* set ctime? */
217	shp->shm_perm.key = IPC_PRIVATE;
218	shp->shm_perm.mode \|= SHM_DEST;
219	if (shp->shm_nattch <= 0)
220	shmfree(shp);
221	break;
222
223	#ifdef HPUXCOMPAT
224	case SHM_LOCK:
225	case SHM_UNLOCK:
226	/* don't really do anything, but make them think we did */
227	if ((u.u_procp->p_flag & SHPUX) == 0)
228	u.u_error = EINVAL;
229	else if (u.u_uid && u.u_uid != shp->shm_perm.uid &&
230	u.u_uid != shp->shm_perm.cuid)
231	u.u_error = EPERM;
232	break;
233	#endif
234
235	default:
236	u.u_error = EINVAL;
237	break;
238	}
239	}
240
241	shmat(ap)
242	int *ap;
243	{
244	struct a {
245	int shmid;
246	caddr_t shmaddr;
247	int shmflg;
248	} uap = (struct a )ap;
249	register struct shmid_ds *shp;
250	register int size;
251	struct mapmem *mp;
252	caddr_t uva;
253	int prot, shmmapin();
254
255	if (!shmvalid(uap->shmid))
256	return;
257	shp = &shmsegs[uap->shmid % SHMMMNI];
258	if (shp->shm_handle == NULL)
259	panic("shmat NULL ptbl");
260	if (!ipcaccess(&shp->shm_perm,
261	(uap->shmflg&SHM_RDONLY) ? IPC_R : IPC_R\|IPC_W))
262	return;
263	uva = uap->shmaddr;
264	if (uva && ((int)uva & (SHMLBA-1))) {
265	if (uap->shmflg & SHM_RND)
266	uva = (caddr_t) ((int)uva & ~(SHMLBA-1));
267	else {
268	u.u_error = EINVAL;
269	return;
270	}
271	}
272	/*
273	* Make sure user doesn't use more than their fair share
274	*/
275	size = 0;
276	for (mp = u.u_mmap; mp; mp = mp->mm_next)
277	if (mp->mm_ops == &shmops)
278	size++;
279	if (size >= shminfo.shmseg) {
280	u.u_error = EMFILE;
281	return;
282	}
283	/*
284	* Allocate a mapped memory region descriptor and
285	* attempt to expand the user page table to allow for region
286	*/
287	prot = (uap->shmflg & SHM_RDONLY) ? MM_RO : MM_RW;
288	#if defined(hp300)
289	prot \|= MM_CI;
290	#endif
291	size = ctob(clrnd(btoc(shp->shm_segsz)));
e5b27ef1	292	mp = mmalloc(uap->shmid, &uva, (segsz_t)size, prot, &shmops);
6f843dc9 KM	293	if (mp == MMNIL)
	294	return;
	295	if (!mmmapin(mp, shmmapin)) {
	296	mmfree(mp);
	297	return;
	298	}
	299	/*
	300	* Fill in the remaining fields
	301	*/
	302	shp->shm_lpid = u.u_procp->p_pid;
	303	shp->shm_atime = time.tv_sec;
	304	shp->shm_nattch++;
	305	u.u_r.r_val1 = (int) uva;
	306	}
	307
	308	shmdt(ap)
	309	int *ap;
	310	{
	311	register struct a {
	312	caddr_t shmaddr;
	313	} uap = (struct a )ap;
	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	u.u_error = EINVAL;
	321	return;
	322	}
	323	shmsegs[mp->mm_id % SHMMMNI].shm_lpid = u.u_procp->p_pid;
	324	shmufree(mp);
	325	}
	326
	327	shmmapin(mp, off)
	328	struct mapmem *mp;
	329	{
	330	register struct shmid_ds *shp;
	331
	332	shp = &shmsegs[mp->mm_id % SHMMMNI];
	333	if (off >= ctob(clrnd(btoc(shp->shm_segsz))))
	334	return(-1);
	335	return(((struct pte *)shp->shm_handle)[btop(off)].pg_pfnum);
	336	}
	337
	338	/*
	339	* Increment attach count on fork
	340	*/
	341	shmfork(mp, ischild)
	342	register struct mapmem *mp;
	343	{
	344	if (!ischild)
	345	shmsegs[mp->mm_id % SHMMMNI].shm_nattch++;
	346	}
	347
	348	/*
	349	* Detach from shared memory segment on exit (or exec)
	350	*/
	351	shmexit(mp)
	352	register struct mapmem *mp;
	353	{
	354	shmufree(mp);
	355	}
	356
357	shmvalid(id)
358	register int id;
359	{
360	register struct shmid_ds *shp;
361
362	if (id < 0 \|\| (id % SHMMMNI) >= shminfo.shmmni)
363	return(0);
364	shp = &shmsegs[id % SHMMMNI];
365	if (shp->shm_perm.seq == (id / SHMMMNI) &&
366	(shp->shm_perm.mode & (SHM_ALLOC\|SHM_DEST)) == SHM_ALLOC)
367	return(1);
368	u.u_error = EINVAL;
369	return(0);
370	}
371
372	/*
373	* Free user resources associated with a shared memory segment
374	*/
375	shmufree(mp)
376	struct mapmem *mp;
377	{
378	register struct shmid_ds *shp;
379
380	shp = &shmsegs[mp->mm_id % SHMMMNI];
381	mmmapout(mp);
382	mmfree(mp);
383	shp->shm_dtime = time.tv_sec;
384	if (--shp->shm_nattch <= 0 && (shp->shm_perm.mode & SHM_DEST))
385	shmfree(shp);
386	}
387
388	/*
389	* Deallocate resources associated with a shared memory segment
390	*/
391	shmfree(shp)
392	register struct shmid_ds *shp;
393	{
394	caddr_t kva;
395
396	if (shp->shm_handle == NULL)
397	panic("shmfree");
398	kva = (caddr_t) ptetokv(shp->shm_handle);
399	free(kva, M_SHM);
400	shp->shm_handle = NULL;
401	shmtot -= clrnd(btoc(shp->shm_segsz));
402	shp->shm_perm.mode = 0;
403	/*
404	* Increment the sequence number to ensure that outstanding
405	* shmids for this segment will be invalid in the event that
406	* the segment is reallocated. Note that shmids must be
407	* positive as decreed by SVID.
408	*/
409	shp->shm_perm.seq++;
410	if ((int)(shp->shm_perm.seq * SHMMMNI) < 0)
411	shp->shm_perm.seq = 0;
412	}
413
414	/*
415	* XXX This routine would be common to all sysV style IPC
416	* (if the others were implemented).
417	*/
418	ipcaccess(ipc, mode)
419	register struct ipc_perm *ipc;
420	{
421	register int m;
422
423	if (u.u_uid == 0)
424	return(0);
425	/*
426	* Access check is based on only one of owner, group, public.
427	* If not owner, then check group.
428	* If not a member of the group, then check public access.
429	*/
430	mode &= 0700;
431	m = ipc->mode;
432	if (u.u_uid != ipc->uid && u.u_uid != ipc->cuid) {
433	m <<= 3;
434	if (!groupmember(ipc->gid, u.u_cred) &&
435	!groupmember(ipc->cgid, u.u_cred))
436	m <<= 3;
437	}
438	if ((mode&m) == mode)
439	return (1);
440	u.u_error = EACCES;
441	return (0);
442	}
443
444	#endif /* SYSVSHM */