From 673753e8befcfbb575380ed0d23fc6741b4e50a0 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Sun, 19 May 2024 23:05:21 -0400
Subject: kernel: vfs: Add support for open hook

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/fs/devfs.c           | 23 ++++++++++++++++++++++-
 sys/include/sys/device.h |  1 +
 sys/include/sys/vfs.h    |  2 ++
 sys/include/sys/vnode.h  |  1 +
 sys/kern/kern_filedesc.c |  7 +++++--
 sys/kern/vfs_subr.c      |  8 ++++++++
 6 files changed, 39 insertions(+), 3 deletions(-)

(limited to 'sys')

diff --git a/sys/fs/devfs.c b/sys/fs/devfs.c
index 79606eb..d7944aa 100644
--- a/sys/fs/devfs.c
+++ b/sys/fs/devfs.c
@@ -157,6 +157,26 @@ vop_read(struct vnode *vp, struct sio_txn *sio)
     return cdev_read(dev, node, sio);
 }
 
+static int
+vop_open(struct vnode *vp)
+{
+    struct device_node *node;
+    struct device *dev;
+
+    if (vp == NULL) {
+        return -EIO;
+    }
+
+    node = vp->data;
+    dev = device_fetch(node->major, node->minor);
+
+    if (dev->open == NULL) {
+        return -EIO;
+    }
+
+    return dev->open(dev);
+}
+
 static int
 devfs_init(struct fs_info *info, struct vnode *source)
 {
@@ -249,5 +269,6 @@ struct vfsops g_devfs_ops = {
 
 struct vops g_devfs_vops = {
     .vget = vop_vget,
-    .read = vop_read
+    .read = vop_read,
+    .open = vop_open
 };
diff --git a/sys/include/sys/device.h b/sys/include/sys/device.h
index 9851ee2..69e367f 100644
--- a/sys/include/sys/device.h
+++ b/sys/include/sys/device.h
@@ -42,6 +42,7 @@ struct device {
     int(*write)(struct device *dev, struct sio_txn *sio);
     int(*read)(struct device *dev, struct sio_txn *sio);
     int(*ioctl)(struct device *dev, uint32_t cmd, uintptr_t arg);
+    int(*open)(struct device *dev);
     paddr_t(*mmap)(struct device *dev, off_t off, vm_prot_t prot);
     TAILQ_ENTRY(device) link;
 };
diff --git a/sys/include/sys/vfs.h b/sys/include/sys/vfs.h
index f5fede8..98aef3f 100644
--- a/sys/include/sys/vfs.h
+++ b/sys/include/sys/vfs.h
@@ -56,7 +56,9 @@ ssize_t vfs_hash_path(const char *path);
 
 ssize_t vfs_read(struct vnode *vp, struct sio_txn *sio);
 ssize_t vfs_write(struct vnode *vp, struct sio_txn *sio);
+
 int vfs_getattr(struct vnode *vp, struct vattr *vattr);
+int vfs_open(struct vnode *vp);
 
 uint64_t sys_mount(struct syscall_args *args);
 
diff --git a/sys/include/sys/vnode.h b/sys/include/sys/vnode.h
index 6dc2cbc..71fc5c2 100644
--- a/sys/include/sys/vnode.h
+++ b/sys/include/sys/vnode.h
@@ -44,6 +44,7 @@ struct vops {
     int(*read)(struct vnode *vp, struct sio_txn *sio);
     int(*write)(struct vnode *vp, struct sio_txn *sio);
     int(*getattr)(struct vnode *vp, struct vattr *vattr);
+    int(*open)(struct vnode *vp);
 };
 
 struct vattr {
diff --git a/sys/kern/kern_filedesc.c b/sys/kern/kern_filedesc.c
index 6bce6d2..74ab859 100644
--- a/sys/kern/kern_filedesc.c
+++ b/sys/kern/kern_filedesc.c
@@ -291,12 +291,15 @@ open(const char *pathname, int oflag)
     int status;
 
     /*
-     * Attempt to create a vnode and allocate a
-     * file descriptor
+     * Attempt to create a vnode, call the open hook then
+     * allocate a file descriptor
      */
     if ((status = vfs_path_to_node(pathname, &vp)) != 0) {
         return status;
     }
+    if ((status = vfs_open(vp)) != 0) {
+        return status;
+    }
     if ((status = fd_alloc(this_td(), &fd)) != 0) {
         return status;
     }
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 5b31057..f760831 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -239,3 +239,11 @@ vfs_getattr(struct vnode *vp, struct vattr *vattr)
 {
     return vp->vops->getattr(vp, vattr);
 }
+
+int vfs_open(struct vnode *vp)
+{
+    if (vp->vops->open == NULL)
+        return -EIO;
+
+    return vp->vops->open(vp);
+}
-- 
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