This patch changes the semantics of sysv shm emulation which is wrongly emulated
under linux.

The patch involves the following functions:
  - shmat
  - shmctl
  - shm_find_segment_by_shmid
  - shm_find_segment_by_shmidx
  - linux_shmat
  - linux_shmctl

`shmat' and `shmctl' are now a wrapper for `shmat1' and `shmctl1'.

The BSD semantic doesn't allow the usage of shared segment after
being marked for removal through IPC_RMID. 
This patch adds a parameter to the functions
  shm{at,ctl}1 and shm_find_segment_by_shmid{x}
that specifies if we want look up segments marked as removed, which
appears to be the Linux semantic.

Patch by: Orlando Bassotto <orlando.bassotto@ieo-research.it>

diff -ru sys/compat/linux/linux_ipc.c sys/compat/linux/linux_ipc.c
--- sys/compat/linux/linux_ipc.c	Sat Mar 29 23:14:31 2003
+++ sys/compat/linux/linux_ipc.c	Sat Mar 29 23:20:47 2003
@@ -662,7 +662,7 @@
     bsd_args.shmid = args->shmid;
     bsd_args.shmaddr = args->shmaddr;
     bsd_args.shmflg = args->shmflg;
-    if ((error = shmat(td, &bsd_args)))
+    if ((error = shmat1(td, &bsd_args, 1)))
 	return error;
 #ifdef __i386__
     if ((error = copyout(td->td_retval, args->raddr, sizeof(l_ulong))))
@@ -718,7 +718,7 @@
 	bsd_args.shmid = args->shmid;
 	bsd_args.cmd = IPC_INFO;
 	bsd_args.buf = (struct shmid_ds*)stackgap_alloc(&sg, sizeof(struct shminfo));
-	if ((error = shmctl(td, &bsd_args)))
+	if ((error = shmctl1(td, &bsd_args, 1)))
 		return error;
 	bsd_to_linux_shminfo( (struct shminfo *)bsd_args.buf, &linux_shminfo );
 	return (linux_shminfo_pushdown(args->cmd & LINUX_IPC_64,
@@ -728,7 +728,7 @@
 	bsd_args.shmid = args->shmid;
 	bsd_args.cmd = SHM_INFO;
 	bsd_args.buf = (struct shmid_ds*)stackgap_alloc(&sg, sizeof(struct shm_info));
-	if ((error = shmctl(td, &bsd_args)))
+	if ((error = shmctl1(td, &bsd_args, 1)))
 	    return error;
 	bsd_to_linux_shm_info( (struct shm_info *)bsd_args.buf, &linux_shm_info );
 	return copyout(&linux_shm_info, (caddr_t)args->buf, sizeof(struct shm_info));
@@ -737,7 +737,7 @@
 	bsd_args.shmid = args->shmid;
 	bsd_args.cmd = IPC_STAT;
 	bsd_args.buf = (struct shmid_ds*)stackgap_alloc(&sg, sizeof(struct shmid_ds));
-	if ((error = shmctl(td, &bsd_args)))
+	if ((error = shmctl1(td, &bsd_args, 1)))
 	    return error;
 	bsd_to_linux_shmid_ds(bsd_args.buf, &linux_shmid);
 	return (linux_shmid_pushdown(args->cmd & LINUX_IPC_64,
@@ -747,7 +747,7 @@
 	bsd_args.shmid = args->shmid;
 	bsd_args.cmd = SHM_STAT;
 	bsd_args.buf = (struct shmid_ds*)stackgap_alloc(&sg, sizeof(struct shmid_ds));
-	if ((error = shmctl(td, &bsd_args))) {
+	if ((error = shmctl1(td, &bsd_args, 1))) {
 	    return error;
 	}
 	bsd_to_linux_shmid_ds(bsd_args.buf, &linux_shmid);
@@ -763,7 +763,7 @@
 	linux_to_bsd_shmid_ds(&linux_shmid, bsd_args.buf);
 	bsd_args.shmid = args->shmid;
 	bsd_args.cmd = IPC_SET;
-	return shmctl(td, &bsd_args);
+	return shmctl1(td, &bsd_args, 1);
 
     case LINUX_IPC_RMID:
 	bsd_args.shmid = args->shmid;
@@ -778,7 +778,7 @@
 	    bsd_args.buf = (struct shmid_ds*)stackgap_alloc(&sg, sizeof(struct shmid_ds));
 	    linux_to_bsd_shmid_ds(&linux_shmid, bsd_args.buf);
 	}
-	return shmctl(td, &bsd_args);
+	return shmctl1(td, &bsd_args, 1);
 
     case LINUX_SHM_LOCK:
     case LINUX_SHM_UNLOCK:
Only in sys.patched.cvs/compat/linux: linux_ipc.c.2
diff -ru sys.cvs/kern/sysv_shm.c sys.patched.cvs/kern/sysv_shm.c
--- sys/kern/sysv_shm.c	Sat Mar 29 23:14:07 2003
+++ sys/kern/sysv_shm.c	Sun Mar 30 04:09:08 2003
@@ -95,8 +95,8 @@
 
 static void shm_deallocate_segment(struct shmid_ds *);
 static int shm_find_segment_by_key(key_t);
-static struct shmid_ds *shm_find_segment_by_shmid(int);
-static struct shmid_ds *shm_find_segment_by_shmidx(int);
+static struct shmid_ds *shm_find_segment_by_shmid(int, int);
+static struct shmid_ds *shm_find_segment_by_shmidx(int, int);
 static int shm_delete_mapping(struct vmspace *vm, struct shmmap_state *);
 static void shmrealloc(void);
 static void shminit(void);
@@ -163,8 +163,9 @@
 }
 
 static struct shmid_ds *
-shm_find_segment_by_shmid(shmid)
+shm_find_segment_by_shmid(shmid, wantrem)
 	int shmid;
+	int wantrem;
 {
 	int segnum;
 	struct shmid_ds *shmseg;
@@ -173,23 +174,23 @@
 	if (segnum < 0 || segnum >= shmalloced)
 		return (NULL);
 	shmseg = &shmsegs[segnum];
-	if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
-	    != SHMSEG_ALLOCATED ||
+	if (!((shmseg->shm_perm.mode & SHMSEG_ALLOCATED) ||
+  		(wantrem && !(shmseg->shm_perm.mode & SHMSEG_REMOVED))) ||
 	    shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid))
 		return (NULL);
 	return (shmseg);
 }
 
 static struct shmid_ds *
-shm_find_segment_by_shmidx(int segnum)
+shm_find_segment_by_shmidx(int segnum, int wantrem)
 {
 	struct shmid_ds *shmseg;
 
 	if (segnum < 0 || segnum >= shmalloced)
 		return (NULL);
 	shmseg = &shmsegs[segnum];
-	if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
-	    != SHMSEG_ALLOCATED )
+	if (!((shmseg->shm_perm.mode & SHMSEG_ALLOCATED) ||
+  		(wantrem && !(shmseg->shm_perm.mode & SHMSEG_REMOVED))))
 		return (NULL);
 	return (shmseg);
 }
@@ -293,9 +294,10 @@
  * MPSAFE
  */
 int
-shmat(td, uap)
+shmat1(td, uap, wantrem)
 	struct thread *td;
 	struct shmat_args *uap;
+	int wantrem;
 {
 	struct proc *p = td->td_proc;
 	int i, flags;
@@ -319,7 +321,7 @@
 			shmmap_s[i].shmid = -1;
 		p->p_vmspace->vm_shm = shmmap_s;
 	}
-	shmseg = shm_find_segment_by_shmid(uap->shmid);
+	shmseg = shm_find_segment_by_shmid(uap->shmid, wantrem);
 	if (shmseg == NULL) {
 		error = EINVAL;
 		goto done2;
@@ -387,6 +389,14 @@
 	return (error);
 }
 
+int
+shmat(td, uap)
+	struct thread *td;
+	struct shmat_args *uap;
+{
+	return shmat1(td, uap, 0);
+}
+
 struct oshmid_ds {
 	struct	ipc_perm shm_perm;	/* operation perms */
 	int	shm_segsz;		/* size of segment (bytes) */
@@ -421,7 +431,7 @@
 	if (!jail_sysvipc_allowed && jailed(td->td_ucred))
 		return (ENOSYS);
 	mtx_lock(&Giant);
-	shmseg = shm_find_segment_by_shmid(uap->shmid);
+	shmseg = shm_find_segment_by_shmid(uap->shmid, 0);
 	if (shmseg == NULL) {
 		error = EINVAL;
 		goto done2;
@@ -469,9 +479,10 @@
  * MPSAFE
  */
 int
-shmctl(td, uap)
+shmctl1(td, uap, wantrem)
 	struct thread *td;
 	struct shmctl_args *uap;
+	int wantrem;
 {
 	int error = 0;
 	struct shmid_ds inbuf;
@@ -503,9 +514,9 @@
 	}
 	}
 	if( (uap->cmd) == SHM_STAT )
-		shmseg = shm_find_segment_by_shmidx(uap->shmid);
+		shmseg = shm_find_segment_by_shmidx(uap->shmid, wantrem);
 	else
-		shmseg = shm_find_segment_by_shmid(uap->shmid);
+		shmseg = shm_find_segment_by_shmid(uap->shmid, wantrem);
 	if (shmseg == NULL) {
 		error = EINVAL;
 		goto done2;
@@ -558,6 +569,14 @@
 done2:
 	mtx_unlock(&Giant);
 	return (error);
+}
+
+int
+shmctl(td, uap)
+	struct thread *td;
+	struct shmctl_args *uap;
+{
+	return shmctl1(td, uap, 0);
 }
 
 #ifndef _SYS_SYSPROTO_H_
diff -ru sys.cvs/sys/sysproto.h sys.patched.cvs/sys/sysproto.h
--- sys/sys/sysproto.h	Sat Mar 29 23:13:36 2003
+++ sys/sys/sysproto.h	Sat Mar 29 23:23:55 2003
@@ -1372,7 +1372,9 @@
 int	msgget(struct thread *, struct msgget_args *);
 int	msgsnd(struct thread *, struct msgsnd_args *);
 int	msgrcv(struct thread *, struct msgrcv_args *);
+int	shmat1(struct thread *, struct shmat_args *, int);
 int	shmat(struct thread *, struct shmat_args *);
+int	shmctl1(struct thread *, struct shmctl_args *, int);
 int	shmctl(struct thread *, struct shmctl_args *);
 int	shmdt(struct thread *, struct shmdt_args *);
 int	shmget(struct thread *, struct shmget_args *);