5: read and write

samples/rust/rust_vdev.rs

@@ -2,34 +2,74 @@
 use kernel::prelude::*;
 
 use kernel::file::{File, Operations};
+use kernel::io_buffer::{IoBufferReader, IoBufferWriter};
+use kernel::sync::smutex::Mutex;
+use kernel::sync::{Ref, RefBorrow};
 use kernel::{miscdev, Module};
 
 module! {
     type: VDev,
     name: b"vdev",
     license: b"GPL",
 }
+struct Device {
+    number: usize,
+    contents: Mutex<Vec<u8>>,
+}
 
 struct VDev {
     _dev: Pin<Box<miscdev::Registration<VDev>>>,
 }
 
 #[vtable]
 impl Operations for VDev {
-    fn open(_context: &(), _file: &File) -> Result {
-        pr_info!("File was opened\n");
-        Ok(())
+    type OpenData = Ref<Device>;
+    type Data = Ref<Device>;
+
+    fn open(context: &Ref<Device>, _file: &File) -> Result<Ref<Device>> {
+        pr_info!("File for device {} was opened\n", context.number);
+        Ok(context.clone())
+    }
+
+    fn read(
+        data: RefBorrow<'_, Device>,
+        _file: &File,
+        writer: &mut impl IoBufferWriter,
+        offset: u64,
+    ) -> Result<usize> {
+        pr_info!("File for device {} was read\n", data.number);
+        let offset = offset.try_into()?;
+        let vec = data.contents.lock();
+        let len = core::cmp::min(writer.len(), vec.len().saturating_sub(offset));
+        writer.write_slice(&vec[offset..][..len])?;
+        Ok(len)
+    }
+
+    fn write(
+        data: RefBorrow<'_, Device>,
+        _file: &File,
+        reader: &mut impl IoBufferReader,
+        _offset: u64,
+    ) -> Result<usize> {
+        pr_info!("File for device {} was written\n", data.number);
+        let copy = reader.read_all()?;
+        let len = copy.len();
+        *data.contents.lock() = copy;
+        Ok(len)
     }
 }
 
 impl Module for VDev {
     fn init(_name: &'static CStr, _module: &'static ThisModule) -> Result<Self> {
-        // Print a banner to make sure our moudle is working
         pr_info!("-----------------------\n");
         pr_info!("initialize vdev module!\n");
         pr_info!("watching for changes...\n");
         pr_info!("-----------------------\n");
-        let reg = miscdev::Registration::new_pinned(fmt!("vdev"), ())?;
+        let dev = Ref::try_new(Device {
+            number: 0,
+            contents: Mutex::new(Vec::new()),
+        })?;
+        let reg = miscdev::Registration::new_pinned(fmt!("vdev"), dev)?;
         Ok(Self { _dev: reg })
     }
 }