vfs+ext2: full implementation of FsNode::open()

ableos/src/filesystem/ext2.rs

@@ -9,7 +9,7 @@ use ext2::sector::SectorSize;
 use ext2::volume::Volume;
 
 use super::errors::FsError;
-use super::{FsResult as Result, StorageDevice};
+use super::{FsResult as Result, StorageDevice, DirectoryEntry, FsNode, FileDescriptor};
 
 pub struct Ext2StorageDevice<S, V>
 where
@@ -36,32 +36,32 @@ where
     S: SectorSize + Send,
     V: Volume<u8, S> + Send,
 {
-    fn open(&self, node: &super::FsNode /* TODO: flags */) -> Result<crate::handle::Handle> {
+    fn open(&self, node: &super::FsNode /* TODO: flags */) -> Result<FileDescriptor> {
         let inode = self
             .fs
             .inode_nth(node.inode as usize)
             .ok_or_else(|| FsError::InodeNotFound)?;
 
-        todo!()
+        Ok(FileDescriptor::new(node.flags, inode.size(), node.inode))
     }
 
     fn close(&self, node: &super::FsNode) -> Result<()> {
         todo!()
     }
 
-    fn read(&self, node: &super::FsNode, offset: u32, size: u32) -> Result<Box<[u8]>> {
+    fn read(&self, node: &super::FsNode, offset: usize, size: usize) -> Result<Box<[u8]>> {
         todo!()
     }
 
-    fn write(&self, node: &super::FsNode, offset: u32, buffer: Box<[u8]>) -> Result<()> {
+    fn write(&self, node: &super::FsNode, offset: usize, buffer: Box<[u8]>) -> Result<()> {
         todo!()
     }
 
-    fn read_dir(&self, node: &super::FsNode, index: u32) -> Result<super::DirectoryEntry> {
+    fn read_dir(&self, node: &super::FsNode, index: usize) -> Result<DirectoryEntry> {
         todo!()
     }
 
-    fn find_dir(&self, node: &super::FsNode, name: &str) -> Result<super::FsNode> {
+    fn find_dir(&self, node: &super::FsNode, name: &str) -> Result<FsNode> {
         todo!()
     }
 }

ableos/src/filesystem/mod.rs

@@ -21,11 +21,11 @@ pub trait StorageDevice
 where
     Self: Send,
 {
-    fn open(&self, node: &FsNode /* TODO: flags */) -> Result<Handle>;
+    fn open(&self, node: &FsNode /* TODO: flags */) -> Result<FileDescriptor>;
     fn close(&self, node: &FsNode) -> Result<()>;
-    fn read(&self, node: &FsNode, offset: u32, size: u32) -> Result<Box<[u8]>>;
-    fn write(&self, node: &FsNode, offset: u32, buffer: Box<[u8]>) -> Result<()>;
-    fn read_dir(&self, node: &FsNode, index: u32) -> Result<DirectoryEntry>;
+    fn read(&self, node: &FsNode, offset: usize, size: usize) -> Result<Box<[u8]>>;
+    fn write(&self, node: &FsNode, offset: usize, buffer: Box<[u8]>) -> Result<()>;
+    fn read_dir(&self, node: &FsNode, index: usize) -> Result<DirectoryEntry>;
     fn find_dir(&self, node: &FsNode, name: &str) -> Result<FsNode>;
 }
 
@@ -35,21 +35,21 @@ where
 /// opened. When there are no open file descriptors to a file, the associated
 /// VFS node is dropped.
 pub struct FsNode {
-    flags: FsNodeFlags,
-    length: u32,           // in bytes
-    fd_count: u32,         // count of open file descriptors
-    inode: u32,            // implementation specific identifier for the node
+    flags: FsFlags,
+    length: usize,         // in bytes
+    fd_count: usize,       // count of open file descriptors
+    inode: usize,          // implementation specific identifier for the node
     device_handle: Handle, // uniquely assigned device handle
     ptr: Weak<FsNode>,     // used by mountpoints and symlinks
-                           // todo: permissions mask
-                           // todo: owning user/group
+                           // TODO: permissions mask
+                           // TODO: owning user/group
 }
 
 impl FsNode {
     pub fn new(
-        flags: FsNodeFlags,
-        length: u32,
-        inode: u32,
+        flags: FsFlags,
+        length: usize,
+        inode: usize,
         device_handle: Handle,
         ptr: Weak<FsNode>,
     ) -> Self {
@@ -65,13 +65,16 @@ impl FsNode {
 
     /// This method opens a new file descriptor for this VFS node.
     // TODO: make this take flags
-    pub fn open(&self) -> Result<Handle> {
+    pub fn open(&mut self) -> Result<Handle> {
         let state = KERNEL_STATE.lock();
         let device = state
             .get_storage_device(self.device_handle)
             .ok_or_else(|| FsError::InvalidDevice)?;
+        let fd = device.open(self)?;
+        let mut kernel_state = KERNEL_STATE.lock();
+        let handle = kernel_state.add_file_descriptor(fd);
 
-        device.open(self)
+        Ok(handle)
     }
 
     /// This method is for closing the VFS node, which is done when no open file
@@ -88,7 +91,7 @@ impl FsNode {
     /// This method reads from the VFS node without opening a new file
     /// descriptor. This is intended to be used internally, if you're trying to
     /// read a file then you probably want to read from a file descriptor.
-    pub fn read(&self, offset: u32, size: u32) -> Result<Box<[u8]>> {
+    pub fn read(&self, offset: usize, size: usize) -> Result<Box<[u8]>> {
         let state = KERNEL_STATE.lock();
         let device = state
             .get_storage_device(self.device_handle)
@@ -100,7 +103,7 @@ impl FsNode {
     /// This method writes to the VFS node without opening a new file
     /// descriptor. This is intended to be used internally, if you're trying to
     /// write to a file then you probably want to write to a file descriptor.
-    pub fn write(&self, offset: u32, buffer: Box<[u8]>) -> Result<()> {
+    pub fn write(&self, offset: usize, buffer: Box<[u8]>) -> Result<()> {
         let state = KERNEL_STATE.lock();
         let device = state
             .get_storage_device(self.device_handle)
@@ -109,7 +112,7 @@ impl FsNode {
         device.write(self, offset, buffer)
     }
 
-    pub fn read_dir(&self, index: u32) -> Result<DirectoryEntry> {
+    pub fn read_dir(&self, index: usize) -> Result<DirectoryEntry> {
         let state = KERNEL_STATE.lock();
         let device = state
             .get_storage_device(self.device_handle)
@@ -129,13 +132,13 @@ impl FsNode {
 }
 
 bitflags! {
-    /// Flags associated with VFS nodes.
+    /// Flags associated with VFS nodes and file descriptors
     ///
     /// 0x00000MST
     /// T is set to 0 for files, 1 for directories
-    /// S is set when the node is a symbolic link
-    /// M is set if the node is an active mount point
-    pub struct FsNodeFlags: u8 {
+    /// S is set when the file is a symbolic link
+    /// M is set if the file is an active mount point
+    pub struct FsFlags: u8 {
         const FILE = 0b00000000;
         const DIRECTORY = 0b00000001;
         const SYMBOLIC_LINK = 0b00000010;
@@ -144,9 +147,28 @@ bitflags! {
 }
 
 /// A file descriptor.
-pub struct FileDescriptor {}
+pub struct FileDescriptor {
+    flags: FsFlags,
+    length: usize, // in bytes
+    inode: usize, // implementation specific identifier for the node
+    // TODO: permissions mask
+    // TODO: owning user/group
+    // TODO: read file position?
+    // FIXME: I'm not sure if this needs to have a ptr to the VFS node,
+    //        figure that out.
+}
+
+impl FileDescriptor {
+    fn new(flags: FsFlags, length: usize, inode: usize) -> Self {
+        Self {
+            flags,
+            length,
+            inode,
+        }
+    }
+}
 
 pub struct DirectoryEntry {
     name: String,
-    inode: u32,
+    inode: usize,
 }

ableos/src/kernel_state.rs

@@ -2,7 +2,7 @@ use hashbrown::HashMap;
 use spin::Lazy;
 
 use crate::{
-    filesystem::StorageDevice,
+    filesystem::{StorageDevice, FileDescriptor},
     handle::{Handle, HandleResource},
 };
 
@@ -12,6 +12,7 @@ pub static KERNEL_STATE: Lazy<spin::Mutex<KernelInternalState>> =
 pub struct KernelInternalState {
     pub hostname: String,
     storage_devices: HashMap<Handle, Box<dyn StorageDevice>>,
+    fd_table: HashMap<Handle, FileDescriptor>,
     should_shutdown: bool,
 }
 
@@ -20,6 +21,7 @@ impl KernelInternalState {
         Self {
             should_shutdown: false,
             storage_devices: HashMap::new(),
+            fd_table: HashMap::new(),
             hostname: "".to_string(),
         }
     }
@@ -28,15 +30,22 @@ impl KernelInternalState {
         self.hostname = hostname;
     }
 
-    pub fn add_storage_device(&mut self, device: impl StorageDevice + Send + 'static) {
-        self.storage_devices
-            .insert(Handle::new(HandleResource::StorageDevice), Box::new(device));
+    pub fn add_storage_device(&mut self, device: impl StorageDevice + Send + 'static) -> Handle {
+        let handle = Handle::new(HandleResource::StorageDevice);
+        self.storage_devices.insert(handle, Box::new(device));
+        handle
     }
 
     pub fn get_storage_device(&self, handle: Handle) -> Option<&dyn StorageDevice> {
         self.storage_devices.get(&handle).map(|d| &**d)
     }
 
+    pub fn add_file_descriptor(&mut self, fd: FileDescriptor) -> Handle {
+        let handle = Handle::new(HandleResource::FileDescriptor);
+        self.fd_table.insert(handle, fd);
+        handle
+    }
+
     pub fn shutdown(&mut self) {
         self.should_shutdown = true;
     }