2 files changed, 47 insertions, 0 deletions
diff --git a/sys/inc/kern/vnode.h b/sys/inc/kern/vnode.h
index 37b7127..407811a 100644
--- a/sys/inc/kern/vnode.h
+++ b/sys/inc/kern/vnode.h
@@ -54,11 +54,23 @@ struct vop_buf_args {
 };
 
 /*
+ * Arguments for lookup() vop
+ *
+ * @component: Path component to lookup
+ * @vp_res: Resulting vnode pointer
+ */
+struct vop_lookup_args {
+    const char *component;
+    struct vnode **vp_res;
+};
+
+/*
  * Operations that can be performed on a vnode
  */
 struct vops {
     ssize_t(*read)(struct vop_buf_args *args);
     ssize_t(*write)(struct vop_buf_args *args);
+    int(*lookup)(struct vop_lookup_args *args);
     void(*reclaim)(struct vnode *vp);
 };
 
@@ -91,6 +103,17 @@ struct vnode {
 ssize_t vnode_read(struct vnode *vp, void *buf, size_t size, off_t off);
 
 /*
+ * Lookup a sub-node within a vnode by name
+ *
+ * @vp: Vnode to scan within
+ * @name: Name to lookup
+ * @res: Result pointer is written here
+ *
+ * Returns zero on success
+ */
+int vnode_lookup(struct vnode *vp, const char *name, struct vnode **res);
+
+/*
  * Write data into a file described by a vnode
  *
  * @vp: Vnode to write
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 2c08f36..c8e3170 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -139,3 +139,27 @@ vnode_write(struct vnode *vp, const void *buf, size_t size, off_t off)
     args.offset = off;
     return vops->write(&args);
 }
+
+int
+vnode_lookup(struct vnode *vp, const char *name, struct vnode **res)
+{
+    struct vop_lookup_args args;
+    struct vops *vops;
+
+    if (vp == NULL || name == NULL) {
+        return -EINVAL;
+    }
+
+    if (res == NULL) {
+        return -EINVAL;
+    }
+
+    vops = &vp->vops;
+    if (vops->lookup == NULL) {
+        return -ENOTSUP;
+    }
+
+    args.component = name;
+    args.vp_res = res;
+    return vops->lookup(&args);
+}