When adding virtual directory entries, check the path to see that

intermediate directories have already been created. If not, then
create the intermediate directories. This means that callers don't
need to create the intermediate directories themselves.

When reading a virtual directory, don't return a zero-length
virtual directory entry.

share/examples/refuse/virtdir/virtdir.c

@@ -61,6 +61,24 @@ strnsave(const char *s, int n)
 	return cp;
 }
 
+/* ensure intermediate directories exist */
+static void
+mkdirs(virtdir_t *tp, const char *path, size_t size)
+{
+	virt_dirent_t	*ep;
+	char		 name[MAXPATHLEN];
+	char		*slash;
+
+	(void) strlcpy(name, path, sizeof(name));
+	for (slash = name + 1 ; (slash = strchr(slash + 1, '/')) != NULL ; ) {
+		*slash = 0x0;
+		if ((ep = virtdir_find(tp, name, strlen(name))) == NULL) {
+			virtdir_add(tp, name, strlen(name), 'd', NULL);
+		}
+		*slash = '/';
+	}
+}
+
 /* initialise the tree */
 int
 virtdir_init(virtdir_t *tp, struct stat *d, struct stat *f, struct stat *l)
@@ -105,6 +123,7 @@ virtdir_add(virtdir_t *tp, const char *name, size_t size, uint8_t type, char *tg
 	}
 	tp->c += 1;
 	qsort(tp->v, tp->c, sizeof(tp->v[0]), compare);
+	mkdirs(tp, name, size);
 	return 1;
 }
 
@@ -165,6 +184,7 @@ readvirtdir(VIRTDIR *dirp)
 				&dirp->tp->v[dirp->i].name[dirp->dirnamelen + 1];
 		if (strncmp(dirp->tp->v[dirp->i].name, dirp->dirname,
 				dirp->dirnamelen) == 0 &&
+		    *from != 0x0 &&
 		    strchr(from, '/') == NULL) {
 			return &dirp->tp->v[dirp->i++];
 		}