3 files changed, 91 insertions, 0 deletions
diff --git a/ayafs-core/src/block_device/disk.rs b/ayafs-core/src/block_device/disk.rs
new file mode 100644
index 0000000..d2beee9
--- /dev/null
+++ b/ayafs-core/src/block_device/disk.rs
@@ -0,0 +1,48 @@
+use crate::block_device::{BlockDevice, BLOCK_SIZE};
+use std::cell::RefCell;
+use std::fs::File;
+use std::io::{Read, Seek, SeekFrom, Write};
+use std::path::{Path, PathBuf};
+
+pub struct Disk {
+    disk_path: PathBuf,
+    device: RefCell<File>,
+}
+
+impl Disk {
+    pub fn new(disk_path: PathBuf) -> Self {
+
+        let device = File::options()
+            .read(true)
+            .write(true)
+            .open(disk_path.as_path())
+            .unwrap();
+        // let device = File::open(disk_path.as_path()).unwrap();
+        Self {
+            disk_path,
+            device: RefCell::new(device),
+        }
+    }
+}
+
+impl BlockDevice for Disk {
+    fn read(&self, block_id: usize, buffer: &mut [u8]) {
+        let mut device = self.device.borrow_mut();
+        device
+            .seek(SeekFrom::Start((block_id * BLOCK_SIZE) as u64))
+            .expect("Unable to seek!");
+        device
+            .read_exact(buffer)
+            .expect("Failed to read 4096 bytes!");
+    }
+
+    fn write(&self, block_id: usize, buffer: &[u8]) {
+        let mut device = self.device.borrow_mut();
+        device
+            .seek(SeekFrom::Start((block_id * BLOCK_SIZE) as u64))
+            .expect("Unable to seek!");
+        device
+            .write_all(buffer)
+            .expect("Unable to write 4096 bytes!");
+    }
+}
diff --git a/ayafs-core/src/block_device/memory_disk.rs b/ayafs-core/src/block_device/memory_disk.rs
new file mode 100644
index 0000000..0639d3e
--- /dev/null
+++ b/ayafs-core/src/block_device/memory_disk.rs
@@ -0,0 +1,33 @@
+use crate::block_device::{BlockDevice, BLOCK_SIZE};
+use std::cell::RefCell;
+
+#[repr(C)]
+pub struct MemoryDisk {
+    /// Emulating a block device with a segment of RAM,
+    /// which is 64MiB == 4KiB per block * 16384 blocks
+    pub arena: RefCell<Vec<u8>>,
+}
+
+impl MemoryDisk {
+    pub fn new(block_number: usize) -> Self {
+        Self {
+            arena: RefCell::new(vec![0u8; BLOCK_SIZE * block_number]),
+        }
+    }
+}
+
+impl BlockDevice for MemoryDisk {
+    fn read(&self, block_id: usize, buffer: &mut [u8]) {
+        let block_front = block_id * BLOCK_SIZE;
+        let block_back = block_front + BLOCK_SIZE;
+        let arena = self.arena.borrow();
+        buffer.copy_from_slice(&arena[block_front..block_back]);
+    }
+
+    fn write(&self, block_id: usize, buffer: &[u8]) {
+        let block_front = block_id * BLOCK_SIZE;
+        let block_back = block_front + BLOCK_SIZE;
+        let mut arena = self.arena.borrow_mut();
+        arena[block_front..block_back].copy_from_slice(buffer);
+    }
+}
diff --git a/ayafs-core/src/block_device/mod.rs b/ayafs-core/src/block_device/mod.rs
new file mode 100644
index 0000000..53394a9
--- /dev/null
+++ b/ayafs-core/src/block_device/mod.rs
@@ -0,0 +1,10 @@
+pub mod disk;
+/// Abstracts for block devices.
+/// Currently only a mock memory disk.
+pub mod memory_disk;
+
+pub const BLOCK_SIZE: usize = 4096;
+pub trait BlockDevice {
+    fn read(&self, block_id: usize, buffer: &mut [u8]);
+    fn write(&self, block_id: usize, buffer: &[u8]);
+}