From 794b3671ed636c4fb8a74e1cf3a636272d4fa3d9 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Fri, 21 Nov 2025 13:48:31 -0500
Subject: kern: vfs: Add vnode lookup VOP

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/inc/kern/vnode.h | 23 +++++++++++++++++++++++
 sys/kern/vfs_subr.c  | 24 ++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

(limited to 'sys')

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
@@ -53,12 +53,24 @@ struct vop_buf_args {
     size_t len;
 };
 
+/*
+ * 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);
 };
 
@@ -90,6 +102,17 @@ 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
  *
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);
+}
-- 
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