kern: vfs: Add vop_getattr() for vnodes

The vop_getattr() allows the caller to obtain information about a file
represented by a specific vnode

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 41 insertions, 0 deletions

diff --git a/src/sys/include/os/vnode.h b/src/sys/include/os/vnode.h
index 628ba68..77cadb2 100644
--- a/src/sys/include/os/vnode.h
+++ b/src/sys/include/os/vnode.h
@@ -94,10 +94,20 @@ struct vop_create_args {
 };
 
 /*
+ * Represents attributes of a vnode
+ *
+ * @size: File size in bytes
+ */
+struct vattr {
+    size_t size;
+};
+
+/*
  * Represents operations that can be performed on
  * a specific vnode. These are implemented as callbacks
  */
 struct vop {
+    int(*getattr)(struct vnode *vp, struct vattr *res);
     int(*lookup)(struct vop_lookup_args *args);
     int(*reclaim)(struct vnode *vp, int flags);
     int(*create)(struct vop_create_args *args);
@@ -200,4 +210,15 @@ int vop_reclaim(struct vnode *vp, int flags);
  */
 int vop_create(struct vnode *vp, struct nameidata *ndp);
 
+/*
+ * Get the attributes of a file
+ *
+ * @vp: Vnode of file to get attributes of
+ * @res: Result of file to get attr of
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value on failure
+ */
+int vop_getattr(struct vnode *vp, struct vattr *res);
+
 #endif  /* !_OS_VNODE_H_ */
diff --git a/src/sys/os/vfs_subr.c b/src/sys/os/vfs_subr.c
index adfcffb..2ae18af 100644
--- a/src/sys/os/vfs_subr.c
+++ b/src/sys/os/vfs_subr.c
@@ -246,3 +246,23 @@ vop_create(struct vnode *vp, struct nameidata *ndp)
     args.ndp = ndp;
     return vops->create(&args);
 }
+
+int
+vop_getattr(struct vnode *vp, struct vattr *res)
+{
+    struct vop *vops;
+
+    if (vp == NULL || res == NULL) {
+        return -EINVAL;
+    }
+
+    if ((vops = vp->vops) == NULL) {
+        return -EIO;
+    }
+
+    if (vops->getattr == NULL) {
+        return -EIO;
+    }
+
+    return vops->getattr(vp, res);
+}