From c63fbabc4266405d9c3dd27e7eac698dce740ccf Mon Sep 17 00:00:00 2001
From: TheOddGarlic <umutinanerdogan@pm.me>
Date: Wed, 3 Aug 2022 12:53:02 +0300
Subject: [PATCH] feat: start VFS implementation

---
 ableos/Cargo.toml               |  2 +-
 ableos/src/filesystem/errors.rs |  9 ++++
 ableos/src/filesystem/mod.rs    | 88 +++++++++++++++++++++++++++++++++
 ableos/src/handle.rs            | 15 ++++--
 4 files changed, 110 insertions(+), 4 deletions(-)
 create mode 100644 ableos/src/filesystem/errors.rs

diff --git a/ableos/Cargo.toml b/ableos/Cargo.toml
index 665889b..a50c735 100644
--- a/ableos/Cargo.toml
+++ b/ableos/Cargo.toml
@@ -58,7 +58,7 @@ test-args = [
 [dependencies]
 lazy_static = { version = "1.4.0", features = ["spin_no_std"] }
 qrcode = { path = "../qrcode-rust" }
-bitflags = "1.2.1"
+bitflags = "1.3"
 lliw = "0.2.0"
 spin = "0.9"
 pretty-hex = "0.2.1"
diff --git a/ableos/src/filesystem/errors.rs b/ableos/src/filesystem/errors.rs
new file mode 100644
index 0000000..01b40a0
--- /dev/null
+++ b/ableos/src/filesystem/errors.rs
@@ -0,0 +1,9 @@
+/*
+ * Copyright (c) 2022, Umut İnan Erdoğan <umutinanerdogan@pm.me>
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+pub enum FsError {
+    UnsupportedOperation,
+}
diff --git a/ableos/src/filesystem/mod.rs b/ableos/src/filesystem/mod.rs
index b712e68..dfec891 100644
--- a/ableos/src/filesystem/mod.rs
+++ b/ableos/src/filesystem/mod.rs
@@ -1,3 +1,13 @@
+/*
+ * Copyright (c) 2022, Umut İnan Erdoğan <umutinanerdogan@pm.me>
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+pub mod errors;
+
+use alloc::rc::Weak;
+use bitflags::bitflags;
 use ext2::{
     fs::{
         sync::{Inode, Synced},
@@ -8,6 +18,84 @@ use ext2::{
 };
 use spin::Lazy;
 
+use crate::handle::Handle;
+
+use self::errors::FsError;
+
+pub type FsOpenOperation = fn(/* TODO: flags */) -> Result<Handle, FsError>;
+pub type FsCloseOperation = fn(fd: Handle) -> Result<(), FsError>;
+pub type FsReadOperation = fn(fd: Handle, offset: u32, size: u32) -> Result<Box<[u8]>, FsError>;
+pub type FsWriteOperation = fn(fd: Handle, offset: u32, buffer: Box<[u8]>) -> Result<(), FsError>;
+
+/// A VFS node, that can either be a file or a directory.
+pub struct FsNode {
+    // FIXME: move the file name into the directory listing to implement hard
+    //        links
+    name: String,
+    flags: FsNodeFlags,
+    length: u32, // in bytes
+    inode: u32, // implementation specific identifier for the node
+    device_handle: Handle, // uniquely assigned device handle
+    ptr: Weak<FsNode>, // used by mountpoints and symlinks
+    open: Option<FsOpenOperation>,
+    close: Option<FsCloseOperation>,
+    read: Option<FsReadOperation>,
+    write: Option<FsWriteOperation>,
+    // todo: permissions mask
+    // todo: owning user/group
+    // todo: readdir, finddir fn pointers
+}
+
+impl FsNode {
+    // TODO: make this take flags
+    fn open(&self) -> Result<Handle, FsError> {
+        if let Some(open) = self.open {
+            open()
+        } else {
+            Err(FsError::UnsupportedOperation)
+        }
+    }
+
+    fn close(&self, fd: Handle) -> Result<(), FsError> {
+        if let Some(close) = self.close {
+            close(fd)
+        } else {
+            Err(FsError::UnsupportedOperation)
+        }
+    }
+
+    fn read(&self, fd: Handle, offset: u32, size: u32) -> Result<Box<[u8]>, FsError> {
+        if let Some(read) = self.read {
+            read(fd, offset, size)
+        } else {
+            Err(FsError::UnsupportedOperation)
+        }
+    }
+
+    fn write(&self, fd: Handle, offset: u32, buffer: Box<[u8]>) -> Result<(), FsError> {
+        if let Some(write) = self.write {
+            write(fd, offset, buffer)
+        } else {
+            Err(FsError::UnsupportedOperation)
+        }
+    }
+}
+
+bitflags! {
+    /// Flags associated with VFS nodes.
+    /// 
+    /// 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 {
+        const FILE = 0b00000000;
+        const DIRECTORY = 0b00000001;
+        const SYMBOLIC_LINK = 0b00000010;
+        const MOUNT_POINT = 0b00000100;
+    }
+}
+
 pub static FILE_SYSTEM: Lazy<spin::Mutex<Synced<Ext2<Size1024, Vec<u8>>>>> =
     Lazy::new(|| spin::Mutex::new(load_fs()));
 
diff --git a/ableos/src/handle.rs b/ableos/src/handle.rs
index dda6239..fb9f31d 100644
--- a/ableos/src/handle.rs
+++ b/ableos/src/handle.rs
@@ -1,3 +1,9 @@
+/*
+ * Copyright (c) 2022, Umut İnan Erdoğan <umutinanerdogan@pm.me>
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
 //! A handle is a u128 with a set of permissions
 //! and a resource connected to it
 
@@ -14,8 +20,9 @@ pub struct BinaryData {
 pub enum HandleResource {
     Channel,
     Socket,
-
     BinaryData,
+    StorageDevice,
+    FileDescriptor,
 }
 
 #[derive(Debug, Eq, Hash, PartialEq, Clone, Copy)]
@@ -30,16 +37,18 @@ impl Display for Handle {
         match &self.res {
             HandleResource::Channel => write!(f, "-Channel")?,
             HandleResource::BinaryData => write!(f, "-Binary")?,
-            Socket => write!(f, "-Socket")?,
+            HandleResource::Socket => write!(f, "-Socket")?,
+            HandleResource::StorageDevice => write!(f, "-StorageDevice")?,
+            HandleResource::FileDescriptor => write!(f, "-FileDescriptor")?,
         }
 
         Ok(())
     }
 }
 
-use crate::handle::HandleResource::*;
 impl Handle {
     pub fn new(htype: HandleResource) -> Self {
+        // FIXME: check if inner collides
         Self {
             inner: generate_process_pass(),
             res: htype,