pulled out the duplicated, conditional code from both kern/vfs_syscalls.c

and compat/common/vfs_syscalls_43.c and placed a single copy of that code
into miscfs/union/union_subr.c (seemed like a good place to put it, since
it's union-fs related).
as a side effect you can build unionfs in lkm.
(netbsd pr#2950, Paul Goyette <paul@pgoyette.bdt.com>)

3 files changed, 98 insertions, 91 deletions

diff --git a/sys/compat/common/vfs_syscalls_43.c b/sys/compat/common/vfs_syscalls_43.c
index e111dec6001..d41f44c457d 100644
--- a/sys/compat/common/vfs_syscalls_43.c
+++ b/sys/compat/common/vfs_syscalls_43.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_syscalls_43.c,v 1.3 1996/09/06 10:37:48 niklas Exp $	*/
+/*	$OpenBSD: vfs_syscalls_43.c,v 1.4 1997/01/02 12:20:42 mickey Exp $	*/
 /*	$NetBSD: vfs_syscalls_43.c,v 1.4 1996/03/14 19:31:52 christos Exp $	*/
 
 /*
@@ -70,6 +70,17 @@
 static void cvtstat __P((struct stat *, struct ostat *));
 
 /*
+ * Redirection info so we don't have to include the union fs routines in 
+ * the kernel directly.  This way, we can build unionfs as an LKM.  The
+ * pointer gets replaced later, when we modload the LKM, or when the
+ * compiled-in unionfs code gets initialized.  Initial, stub routine
+ * value is compiled in from kern/vfs_syscalls.c
+ */
+
+extern int (*union_check_p)  __P((struct proc *, struct vnode **, 
+				   struct file *, struct uio, int *));
+
+/*
  * Convert from an old to a new stat structure.
  */
 static void
@@ -380,7 +391,7 @@ compat_43_sys_getdirentries(p, v, retval)
 		syscallarg(u_int) count;
 		syscallarg(long *) basep;
 	} */ *uap = v;
-	register struct vnode *vp;
+	struct vnode *vp;
 	struct file *fp;
 	struct uio auio, kuio;
 	struct iovec aiov, kiov;
@@ -461,50 +472,12 @@ unionread:
 	VOP_UNLOCK(vp);
 	if (error)
 		return (error);
-
-#ifdef UNION
-{
-	extern int (**union_vnodeop_p) __P((void *));
-	extern struct vnode *union_dircache __P((struct vnode *));
-
 	if ((SCARG(uap, count) == auio.uio_resid) &&
-	    (vp->v_op == union_vnodeop_p)) {
-		struct vnode *lvp;
-
-		lvp = union_dircache(vp);
-		if (lvp != NULLVP) {
-			struct vattr va;
-
-			/*
-			 * If the directory is opaque,
-			 * then don't show lower entries
-			 */
-			error = VOP_GETATTR(vp, &va, fp->f_cred, p);
-			if (va.va_flags & OPAQUE) {
-				vput(lvp);
-				lvp = NULL;
-			}
-		}
-		
-		if (lvp != NULLVP) {
-			error = VOP_OPEN(lvp, FREAD, fp->f_cred, p);
-			VOP_UNLOCK(lvp);
-
-			if (error) {
-				vrele(lvp);
-				return (error);
-			}
-			fp->f_data = (caddr_t) lvp;
-			fp->f_offset = 0;
-			error = vn_close(vp, FREAD, fp->f_cred, p);
-			if (error)
-				return (error);
-			vp = lvp;
-			goto unionread;
-		}
-	}
-}
-#endif /* UNION */
+	    union_check_p &&
+	    (union_check_p(p, &vp, fp, auio, &error) != 0))
+		goto unionread;
+	if (error)
+		return (error);
 
 	if ((SCARG(uap, count) == auio.uio_resid) &&
 	    (vp->v_flag & VROOT) &&
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 8598b025358..e377f948272 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_syscalls.c,v 1.17 1996/10/27 08:02:32 tholo Exp $	*/
+/*	$OpenBSD: vfs_syscalls.c,v 1.18 1997/01/02 12:20:40 mickey Exp $	*/
 /*	$NetBSD: vfs_syscalls.c,v 1.71 1996/04/23 10:29:02 mycroft Exp $	*/
 
 /*
@@ -69,6 +69,17 @@ void checkdirs __P((struct vnode *));
 int dounmount __P((struct mount *, int, struct proc *));
 
 /*
+ * Redirection info so we don't have to include the union fs routines in 
+ * the kernel directly.  This way, we can build unionfs as an LKM.  The
+ * pointer gets filled in later, when we modload the LKM, or when the
+ * compiled-in unionfs code gets initialized.  For now, we just set
+ * it to a stub routine.
+ */
+
+int (*union_check_p) __P((struct proc *, struct vnode **, 
+			   struct file *, struct uio, int *)) = NULL;
+
+/*
  * Virtual File System System Calls
  */
 
@@ -1992,7 +2003,7 @@ sys_getdirentries(p, v, retval)
 		syscallarg(u_int) count;
 		syscallarg(long *) basep;
 	} */ *uap = v;
-	register struct vnode *vp;
+	struct vnode *vp;
 	struct file *fp;
 	struct uio auio;
 	struct iovec aiov;
@@ -2022,50 +2033,12 @@ unionread:
 	VOP_UNLOCK(vp);
 	if (error)
 		return (error);
-
-#ifdef UNION
-{
-	extern int (**union_vnodeop_p) __P((void *));
-	extern struct vnode *union_dircache __P((struct vnode *));
-
 	if ((SCARG(uap, count) == auio.uio_resid) &&
-	    (vp->v_op == union_vnodeop_p)) {
-		struct vnode *lvp;
-
-		lvp = union_dircache(vp);
-		if (lvp != NULLVP) {
-			struct vattr va;
-
-			/*
-			 * If the directory is opaque,
-			 * then don't show lower entries
-			 */
-			error = VOP_GETATTR(vp, &va, fp->f_cred, p);
-			if (va.va_flags & OPAQUE) {
-				vput(lvp);
-				lvp = NULL;
-			}
-		}
-		
-		if (lvp != NULLVP) {
-			error = VOP_OPEN(lvp, FREAD, fp->f_cred, p);
-			VOP_UNLOCK(lvp);
-
-			if (error) {
-				vrele(lvp);
-				return (error);
-			}
-			fp->f_data = (caddr_t) lvp;
-			fp->f_offset = 0;
-			error = vn_close(vp, FREAD, fp->f_cred, p);
-			if (error)
-				return (error);
-			vp = lvp;
-			goto unionread;
-		}
-	}
-}
-#endif /* UNION */
+	    union_check_p &&
+	    (union_check_p(p, &vp, fp, auio, &error) != 0))
+		goto unionread;
+	if (error)
+		return (error);
 
 	if ((SCARG(uap, count) == auio.uio_resid) &&
 	    (vp->v_flag & VROOT) &&
diff --git a/sys/miscfs/union/union_subr.c b/sys/miscfs/union/union_subr.c
index 408de9951e2..546c1958e2f 100644
--- a/sys/miscfs/union/union_subr.c
+++ b/sys/miscfs/union/union_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: union_subr.c,v 1.3 1996/12/07 13:00:16 deraadt Exp $	*/
+/*	$OpenBSD: union_subr.c,v 1.4 1997/01/02 12:20:43 mickey Exp $	*/
 /*	$NetBSD: union_subr.c,v 1.18 1996/02/09 22:41:10 christos Exp $	*/
 
 /*
@@ -80,6 +80,66 @@ int union_vn_close __P((struct vnode *, int, struct ucred *, struct proc *));
 static void union_dircache_r __P((struct vnode *, struct vnode ***, int *));
 struct vnode *union_dircache __P((struct vnode *));
 
+/*
+ * This variable is used to hold a pointer to a function
+ * that is called from vfs_syscalls.c and vfs_syscalls_43.c 
+ * - by keeping a pointer to the function we enable the real
+ * union filesystem code to replace the stub value provided
+ * by vfs_syscalls.c and thus vfs_syscalls.c no longer needs
+ * to know if UNION is built in, lkm'ed, or not even there.
+ */
+extern
+int (*union_check_p) __P((struct proc *, struct vnode **, 
+			   struct file *, struct uio, int *));
+
+int union_check(struct proc *, struct vnode **, struct file *,
+		 struct uio, int *);
+
+int union_check(p, vpp, fp, auio, error)
+	struct proc	*p;
+	struct vnode	**vpp;
+	struct file	*fp;
+	struct uio	auio;
+	int		*error;
+{
+	if ((*vpp)->v_op == union_vnodeop_p) {
+		struct vnode *lvp;
+
+		lvp = union_dircache(*vpp);
+		if (lvp != NULLVP) {
+			struct vattr va;
+
+			/*
+			 * If the directory is opaque,
+			 * then don't show lower entries
+			 */
+			*error = VOP_GETATTR(*vpp, &va, fp->f_cred, p);
+			if (va.va_flags & OPAQUE) {
+				vput(lvp);
+				lvp = NULL;
+			}
+		}
+
+		if (lvp != NULLVP) {
+			*error = VOP_OPEN(lvp, FREAD, fp->f_cred, p);
+			VOP_UNLOCK(lvp);
+
+			if (*error) {
+				vrele(lvp);
+				return (0);
+			}
+			fp->f_data = (caddr_t) lvp;
+			fp->f_offset = 0;
+			*error = vn_close(*vpp, FREAD, fp->f_cred, p);
+			if (*error)
+				return (0);
+			*vpp = lvp;
+			return (1);
+		}
+	}
+	return (0);
+};
+
 void
 union_init()
 {
@@ -88,6 +148,7 @@ union_init()
 	for (i = 0; i < NHASH; i++)
 		LIST_INIT(&unhead[i]);
 	bzero((caddr_t) unvplock, sizeof(unvplock));
+	union_check_p = union_check;
 }
 
 static int