vi and busybox

src/drivers/storage/block.rs

@@ -0,0 +1,67 @@
+#[derive(Clone, Copy, PartialEq, Eq)]
+#[allow(dead_code)]
+pub enum BlockError {
+    NoDevice,
+    Io,
+    Unsupported,
+    Invalid,
+}
+
+pub trait BlockDevice {
+    fn sector_size(&self) -> usize {
+        512
+    }
+
+    fn read_sector(&mut self, lba: u64, buffer: &mut [u8]) -> Result<(), BlockError>;
+
+    fn write_sector(&mut self, _lba: u64, _buffer: &[u8]) -> Result<(), BlockError> {
+        Err(BlockError::Unsupported)
+    }
+
+    fn read_at(&mut self, offset: u64, buffer: &mut [u8]) -> Result<(), BlockError> {
+        let sector_size = self.sector_size();
+        if sector_size == 0 {
+            return Err(BlockError::Invalid);
+        }
+
+        let mut done = 0;
+        let mut scratch = [0u8; 512];
+        while done < buffer.len() {
+            let absolute = offset + done as u64;
+            let lba = absolute / sector_size as u64;
+            let sector_offset = (absolute % sector_size as u64) as usize;
+            self.read_sector(lba, &mut scratch)?;
+
+            let chunk = (sector_size - sector_offset).min(buffer.len() - done);
+            buffer[done..done + chunk]
+                .copy_from_slice(&scratch[sector_offset..sector_offset + chunk]);
+            done += chunk;
+        }
+
+        Ok(())
+    }
+
+    fn write_at(&mut self, offset: u64, buffer: &[u8]) -> Result<(), BlockError> {
+        let sector_size = self.sector_size();
+        if sector_size == 0 {
+            return Err(BlockError::Invalid);
+        }
+
+        let mut done = 0;
+        let mut scratch = [0u8; 512];
+        while done < buffer.len() {
+            let absolute = offset + done as u64;
+            let lba = absolute / sector_size as u64;
+            let sector_offset = (absolute % sector_size as u64) as usize;
+            self.read_sector(lba, &mut scratch)?;
+
+            let chunk = (sector_size - sector_offset).min(buffer.len() - done);
+            scratch[sector_offset..sector_offset + chunk]
+                .copy_from_slice(&buffer[done..done + chunk]);
+            self.write_sector(lba, &scratch)?;
+            done += chunk;
+        }
+
+        Ok(())
+    }
+}