--- src/usr.bin/fstat/fstat.c.orig	Sat Jan 14 02:18:03 2006
+++ src/usr.bin/fstat/fstat.c	Sun Aug 12 13:35:06 2007
@@ -51,6 +51,7 @@
 #include <sys/user.h>
 #include <sys/stat.h>
 #include <sys/vnode.h>
+#include <sys/namei.h>
 #include <sys/socket.h>
 #include <sys/socketvar.h>
 #include <sys/domain.h>
@@ -69,7 +70,9 @@
 #include <ufs/ufs/inode.h>
 #include <fs/devfs/devfs.h>
 #include <fs/devfs/devfs_int.h>
+#include <fs/unionfs/union.h>
 #undef _KERNEL
+
 #include <nfs/nfsproto.h>
 #include <nfs/rpcv2.h>
 #include <nfsclient/nfs.h>
@@ -108,6 +111,9 @@
 #define	TRACE	-4
 #define	MMAP	-5
 #define	JDIR	-6
+#define	UNIONUNDEF	-7
+#define	UNIONLOWER	-8
+#define	UNIONUPPER	-9
 
 DEVS *devs;
 
@@ -147,6 +153,8 @@
 void dommap(struct kinfo_proc *kp);
 void vtrans(struct vnode *vp, int i, int flag);
 int  ufs_filestat(struct vnode *vp, struct filestat *fsp);
+int  unionfs_filestat(struct vnode *vp, struct filestat *fsp);
+struct vnode *unionfs_filestat_new(struct vnode *vp, int *i);
 int  nfs_filestat(struct vnode *vp, struct filestat *fsp);
 int  devfs_filestat(struct vnode *vp, struct filestat *fsp);
 char *getmnton(struct mount *m);
@@ -314,6 +322,15 @@
 	case JDIR: \
 		printf(" jail"); \
 		break; \
+	case UNIONUNDEF: \
+		printf(" undf"); \
+		break; \
+	case UNIONLOWER: \
+		printf(" ulow"); \
+		break; \
+	case UNIONUPPER: \
+		printf(" uup"); \
+		break; \
 	default: \
 		printf(" %4d", i); \
 		break; \
@@ -490,6 +507,9 @@
 	struct filestat fst;
 	char rw[3], mode[15], tagstr[12], *tagptr;
 	const char *badtype, *filename;
+	struct vnode *unionvp = NULL;
+	int unionflag = 0;
+	int unionfiletype = 0;
 
 	filename = badtype = NULL;
 	if (!KVM_READ(vp, &vn, sizeof (struct vnode))) {
@@ -524,6 +544,17 @@
 		} else if (!strcmp("isofs", tagstr)) {
 			if (!isofs_filestat(&vn, &fst))
 				badtype = "error";
+		} else if (!strcmp("unionfs", tagstr)) {
+			if (!unionfs_filestat(&vn, &fst))
+				badtype = "error";
+			/* also diplay vnode of interest */
+			unionvp = unionfs_filestat_new(&vn,&unionfiletype);
+			if (unionvp == NULL) {
+				unionflag = 0;
+			}
+			else {
+				unionflag = 1;
+			}
 		} else {
 			static char unknown[32];
 			snprintf(unknown, sizeof unknown, "?(%s)", tagstr);
@@ -586,7 +617,36 @@
 	printf(" %2s", rw);
 	if (filename && !fsflg)
 		printf("  %s", filename);
+	if ( unionflag == 1 && unionvp != NULL ) {
+		if (!KVM_READ(unionvp, &vn, sizeof (struct vnode))) {
+			dprintf(stderr, "can't read vnode at %p for pid %d\n",
+			    (void *)vp, Pid);
+			return;
+		}
+		switch (unionfiletype) {
+		case UNIONLOWER:
+			printf("  unionlower");
+			break;
+		case UNIONUPPER:
+			printf("  unionupper");
+			break;
+		default:
+			printf("  unionundef");
+		}
+#if 0
+		/* need some more logic to do this lookup */
+		if (nflg)
+			/* lookup fst.fsid for vnode */
+			(void)printf(" %2d,%-2d", major(fst.fsid), minor(fst.fsid));
+		else {
+#endif
+			(void)printf(" %-8s", getmnton(vn.v_mount));
+#if 0
+		}
+#endif
+	}
 	putchar('\n');
+
 }
 
 int
@@ -620,6 +680,88 @@
 
 	return 1;
 }
+
+int
+unionfs_filestat(struct vnode *vp, struct filestat *fsp)
+{
+	struct unionfs_node unode;
+	struct vnode lower;
+	struct vnode upper;
+	int res;
+
+	if (!KVM_READ(VTOUNIONFS(vp), &unode, sizeof (unode))) {
+		dprintf(stderr, "can't read unionfs_node at %p for pid %d\n",
+		    (void *)VTOUNIONFS(vp), Pid);
+		return 0;
+	}
+
+	/* find the vnode of the file, if it exists */
+	if (unode.un_uppervp != NULL ) {
+		if (!KVM_READ(unode.un_uppervp, &upper,
+			sizeof (struct vnode))) {
+			dprintf(stderr,
+				"can't read upper vnode at %p for pid %d\n",
+				(void *)vp, Pid);
+			return 0;
+		}
+		/* fprintf(stderr,"found upper vnode\n"); */
+		res = ufs_filestat(&upper, fsp);
+	}
+	else if (unode.un_lowervp != NULL ) {
+		if (!KVM_READ(unode.un_lowervp, &lower,
+			sizeof (struct vnode))) {
+			dprintf(stderr,
+				"can't read lower vnode at %p for pid %d\n",
+				(void *)vp, Pid);
+			return 0;
+		}
+		/* fprintf(stderr,"found lower vnode\n"); */
+		res = ufs_filestat(&lower, fsp);
+	}
+	else {
+		/* neither lower or upper exist */
+		dprintf(stderr, "neither lower nor upper vnode defined\n");
+		fsp->fsid = 0;
+		fsp->fileid = 0;
+		fsp->mode = 0;
+		fsp->size = 0;
+		fsp->rdev = 0;
+		return 0;
+	}
+
+	return res;
+}
+
+struct vnode *
+unionfs_filestat_new(struct vnode *vp, int *i)
+{
+	struct unionfs_node unode;
+
+	if (!KVM_READ(VTOUNIONFS(vp), &unode, sizeof (unode))) {
+		dprintf(stderr, "can't read unionfs_node at %p for pid %d\n",
+		    (void *)VTOUNIONFS(vp), Pid);
+		return 0;
+	}
+
+	/* find the vnode of the file, if it exists */
+	if (unode.un_uppervp != NULL ) {
+		*i = UNIONUPPER;
+		return (unode.un_uppervp);
+	}
+	else if (unode.un_lowervp != NULL ) {
+		*i = UNIONLOWER;
+		return (unode.un_lowervp);
+	}
+	else {
+		/* neither lower or upper exist */
+		dprintf(stderr, "neither lower nor upper vnode defined\n");
+		*i = UNIONUNDEF;
+		return (NULL);
+	}
+
+}
+
+
 
 int
 devfs_filestat(struct vnode *vp, struct filestat *fsp)