From 732d6c11f39cb3d9646f8077a1df2b453659ddaa Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Tue, 7 Oct 2025 15:35:53 -0400
Subject: kern: vfs: Add write vop to vnodes

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 src/sys/include/os/vnode.h | 27 +++++++++++++++++++++++++++
 src/sys/os/vfs_subr.c      | 25 +++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

(limited to 'src')

diff --git a/src/sys/include/os/vnode.h b/src/sys/include/os/vnode.h
index 354c73c..77459a1 100644
--- a/src/sys/include/os/vnode.h
+++ b/src/sys/include/os/vnode.h
@@ -66,12 +66,27 @@ struct vop_lookup_args {
     struct vnode **vpp;
 };
 
+/*
+ * Represents VOP data that can be used to read
+ * or write a file, etc
+ *
+ * @data: Buffer containing I/O data
+ * @len: Length of buffer
+ * @vp: Current vnode
+ */
+struct vop_rw_data {
+    void *data;
+    size_t len;
+    struct vnode *vp;
+};
+
 /*
  * Represents operations that can be performed on
  * a specific vnode. These are implemented as callbacks
  */
 struct vop {
     int(*lookup)(struct vop_lookup_args *args);
+    ssize_t(*write)(struct vop_rw_data *data);
 };
 
 /*
@@ -120,4 +135,16 @@ int vfs_valloc(struct vnode **resp, vtype_t type, int flags);
  */
 int vfs_vrel(struct vnode *vp, int flags);
 
+/*
+ * Wrapper for the vnode write callback
+ *
+ * @vp: Vnode to write to
+ * @data: Data to write
+ * @len: Length of bytes to write
+ *
+ * Returns the number of bytes written on success, otherwise
+ * a less than zero value on failure.
+ */
+ssize_t vop_write(struct vnode *vp, char *data, size_t len);
+
 #endif  /* !_OS_VNODE_H_ */
diff --git a/src/sys/os/vfs_subr.c b/src/sys/os/vfs_subr.c
index 64c7492..b82b683 100644
--- a/src/sys/os/vfs_subr.c
+++ b/src/sys/os/vfs_subr.c
@@ -143,3 +143,28 @@ vfs_cmp_cnt(const char *path)
 
     return cnt + 1;
 }
+
+ssize_t
+vop_write(struct vnode *vp, char *data, size_t len)
+{
+    struct vop_rw_data rwdata;
+    struct vop *vops;
+
+    if (vp == NULL || data == NULL) {
+        return -EINVAL;
+    }
+
+    if (len == 0) {
+        return -EINVAL;
+    }
+
+    /* Grab the virtual operations */
+    if ((vops = vp->vops) == NULL) {
+        return -EIO;
+    }
+
+    rwdata.data = data;
+    rwdata.len = len;
+    rwdata.vp = vp;
+    return vops->write(&rwdata);
+}
-- 
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