Impl some INode functions.

src/sfs.rs

@@ -1,16 +1,35 @@
 use spin::Mutex;
 use bit_set::BitSet;
-use alloc::{boxed::Box, Vec, BTreeMap, rc::Rc};
+use alloc::{boxed::Box, Vec, BTreeMap, rc::{Rc, Weak}};
+use core::cell::{RefCell, RefMut};
 use dirty::Dirty;
 use super::structs::*;
+use super::vfs;
 use core::mem::{uninitialized, size_of};
 use core::slice;
 
 /// Interface for SFS to read & write
 ///     TODO: use std::io::{Read, Write}
 pub trait Device {
-    fn read_at(&mut self, offset: u64, buf: &mut [u8]) -> Option<usize>;
-    fn write_at(&mut self, offset: u64, buf: &[u8]) -> Option<usize>;
+    fn read_at(&mut self, offset: usize, buf: &mut [u8]) -> Option<usize>;
+    fn write_at(&mut self, offset: usize, buf: &[u8]) -> Option<usize>;
+
+    // Helper functions
+
+    fn read_block(&mut self, id: BlockId, offset: usize, buf: &mut [u8]) -> Result<(),()> {
+        debug_assert!(offset + buf.len() <= BLKSIZE);
+        match self.read_at(id * BLKSIZE + offset, buf) {
+            Some(len) if len == buf.len() => Ok(()),
+            _ => Err(()),
+        }
+    }
+    fn write_block(&mut self, id: BlockId, offset: usize, buf: &[u8]) -> Result<(),()> {
+        debug_assert!(offset + buf.len() <= BLKSIZE);
+        match self.write_at(id * BLKSIZE + offset, buf) {
+            Some(len) if len == buf.len() => Ok(()),
+            _ => Err(()),
+        }
+    }
 }
 
 /// inode for sfs
@@ -19,9 +38,121 @@ pub struct INode {
     disk_inode: Dirty<DiskINode>,
     /// inode number
     id: INodeId,
+    /// Reference to SFS, used by almost all operations
+    fs: Rc<RefCell<SimpleFileSystem>>,
+}
+
+impl INode {
+    /// Map file block id to disk block id
+    fn disk_block_id(&self, file_block_id: BlockId) -> Option<BlockId> {
+        match file_block_id {
+            id if id >= self.disk_inode.blocks as BlockId =>
+                None,
+            id if id < NDIRECT =>
+                Some(self.disk_inode.direct[id] as BlockId),
+            id if id < NDIRECT + BLK_NENTRY => {
+                let mut disk_block_id: BlockId = 0;
+                self.fs.borrow_mut().device.read_block(
+                    self.disk_inode.indirect as usize,
+                    ENTRY_SIZE * (id - NDIRECT),
+                    disk_block_id.as_buf_mut()
+                ).unwrap();
+                Some(disk_block_id as BlockId)
+            },
+            id => unimplemented!("double indirect blocks is not supported"),
+        }
+    }
+}
+
+impl vfs::INode for INode {
+    fn open(&mut self, flags: u32) -> Result<(), ()> {
+        // Do nothing
+        Ok(())
+    }
+    fn close(&mut self) -> Result<(), ()> {
+        self.sync()
+    }
+    fn read_at(&mut self, offset: usize, buf: &mut [u8]) -> Option<usize> {
+        let mut fs = self.fs.borrow_mut();
+
+        let iter = BlockIter {
+            begin: offset,
+            end: offset + buf.len(),
+        };
+
+        // Read for each block
+        let mut buf_offset = 0usize;
+        for BlockRange{block, begin, end} in iter {
+            if let Some(disk_block_id) = self.disk_block_id(block) {
+                let len = end - begin;
+                fs.device.read_block(disk_block_id, begin, &mut buf[buf_offset .. buf_offset + len]);
+                buf_offset += len;
+            } else {
+                // Failed this time
+                break;
+            }
+        }
+        Some(buf_offset)
+    }
+    fn write_at(&mut self, offset: usize, buf: &[u8]) -> Option<usize> {
+        let mut fs = self.fs.borrow_mut();
+
+        let iter = BlockIter {
+            begin: offset,
+            end: offset + buf.len(),
+        };
+
+        // Read for each block
+        let mut buf_offset = 0usize;
+        for BlockRange{block, begin, end} in iter {
+            if let Some(disk_block_id) = self.disk_block_id(block) {
+                let len = end - begin;
+                fs.device.write_block(disk_block_id, begin, &buf[buf_offset .. buf_offset + len]);
+                buf_offset += len;
+            } else {
+                // Failed this time
+                break;
+            }
+        }
+        Some(buf_offset)
+    }
+    fn sync(&mut self) -> Result<(), ()> {
+        if self.disk_inode.dirty() {
+            let mut fs = self.fs.borrow_mut();
+            fs.device.write_block(self.id, 0, self.disk_inode.as_buf())?;
+            self.disk_inode.sync();
+        }
+        Ok(())
+    }
+}
+
+/// Given a range and iterate sub-range for each block
+struct BlockIter {
+    begin: usize,
+    end: usize,
+}
+
+struct BlockRange {
+    block: BlockId,
+    begin: usize,
+    end: usize,
+}
+
+impl Iterator for BlockIter {
+    type Item = BlockRange;
+
+    fn next(&mut self) -> Option<<Self as Iterator>::Item> {
+        if self.begin >= self.end {
+            return None;
+        }
+        let block = self.begin / BLKSIZE;
+        let begin = self.begin % BLKSIZE;
+        let end = if block == self.end / BLKSIZE {self.end % BLKSIZE} else {BLKSIZE};
+        self.begin += end - begin;
+        Some(BlockRange {block, begin, end})
+    }
 }
 
-type INodeId = usize;
 
 /// filesystem for sfs
 pub struct SimpleFileSystem {
@@ -39,7 +170,7 @@ impl SimpleFileSystem {
     /// Create a new SFS with device
     pub fn new(mut device: Box<Device>) -> Option<Self> {
         let mut super_block: SuperBlock = unsafe{ uninitialized() };
-        if device.read_at(0, super_block.as_buf_mut()).is_none() {
+        if device.read_at(BLKN_SUPER * BLKSIZE, super_block.as_buf_mut()).is_none() {
             return None;
         }
         if super_block.check() == false {
@@ -86,6 +217,26 @@ impl SimpleFileSystem {
     }
 }
 
+impl vfs::FileSystem for SimpleFileSystem {
+    type INode = INode;
+
+    fn sync(&mut self) -> Result<(), ()> {
+        unimplemented!()
+    }
+
+    fn root_inode(&mut self) -> Rc<INode> {
+        unimplemented!()
+    }
+
+    fn unmount(&mut self) -> Result<(), ()> {
+        unimplemented!()
+    }
+
+    fn cleanup(&mut self) {
+        unimplemented!()
+    }
+}
+
 trait BitsetAlloc {
     fn alloc(&mut self) -> Option<usize>;
 }

src/structs.rs

@@ -12,7 +12,7 @@ pub struct SuperBlock {
     pub blocks: u32,
     /// number of unused blocks in fs
     pub unused_blocks: u32,
-    /// infomation for sfs
+    /// information for sfs
     pub info: [u8; MAX_INFO_LEN + 1],
 }
 
@@ -23,7 +23,7 @@ pub struct DiskINode {
     /// size of the file (in bytes)
     pub size: u32,
     /// one of SYS_TYPE_* above
-    pub type_: u16,
+    pub type_: FileType,
     /// number of hard links to this file
     pub nlinks: u16,
     /// number of blocks
@@ -36,6 +36,11 @@ pub struct DiskINode {
     pub db_indirect: u32,
 }
 
+#[repr(C, packed)]
+pub struct IndirectBlock {
+    pub entrys: [u32; BLK_NENTRY],
+}
+
 /// file entry (on disk)
 #[repr(C, packed)]
 pub struct DiskEntry {
@@ -63,11 +68,15 @@ pub trait AsBuf {
 
 impl AsBuf for SuperBlock {}
 impl AsBuf for DiskINode {}
+impl AsBuf for BlockId {}
 
 /*
  * Simple FS (SFS) definitions visible to ucore. This covers the on-disk format
  * and is used by tools that work on SFS volumes, such as mksfs.
  */
+pub type BlockId = usize;
+pub type INodeId = BlockId;
+
 /// magic number for sfs
 pub const MAGIC: u32 = 0x2f8dbe2a;
 /// size of block
@@ -81,17 +90,21 @@ pub const MAX_FNAME_LEN: usize = 255;
 /// max file size (128M)
 pub const MAX_FILE_SIZE: usize = 1024 * 1024 * 128;
 /// block the superblock lives in
-pub const BLKN_SUPER: usize = 0;
+pub const BLKN_SUPER: BlockId = 0;
 /// location of the root dir inode
-pub const BLKN_ROOT: usize = 1;
+pub const BLKN_ROOT: BlockId = 1;
 /// 1st block of the freemap
-pub const BLKN_FREEMAP: usize = 2;
+pub const BLKN_FREEMAP: BlockId = 2;
 /// number of bits in a block
 pub const BLKBITS: usize = BLKSIZE * 8;
+///
+pub const ENTRY_SIZE: usize = 4;
 /// number of entries in a block
-pub const BLK_NENTRY: usize = BLKSIZE / 4;
+pub const BLK_NENTRY: usize = BLKSIZE / ENTRY_SIZE;
 
 /// file types
+#[repr(u16)]
+#[derive(Debug)]
 pub enum FileType {
     Invalid = 0, File = 1, Dir = 2, Link = 3,
 }
@@ -106,5 +119,6 @@ mod test {
         assert!(size_of::<SuperBlock>() <= BLKSIZE);
         assert!(size_of::<DiskINode>() <= BLKSIZE);
         assert!(size_of::<DiskEntry>() <= BLKSIZE);
+        assert_eq!(size_of::<IndirectBlock>(), BLKSIZE);
     }
 }

src/tests.rs

@@ -2,16 +2,19 @@ use std::fs::File;
 use std::io::{Read, Write, Seek, SeekFrom};
 use std::boxed::Box;
 use super::sfs::*;
+use super::vfs::*;
 
 impl Device for File {
-    fn read_at(&mut self, offset: u64, buf: &mut [u8]) -> Option<usize> {
+    fn read_at(&mut self, offset: usize, buf: &mut [u8]) -> Option<usize> {
+        let offset = offset as u64;
         match self.seek(SeekFrom::Start(offset)) {
             Ok(real_offset) if real_offset == offset => self.read(buf).ok(),
             _ => None,
         }
     }
 
-    fn write_at(&mut self, offset: u64, buf: &[u8]) -> Option<usize> {
+    fn write_at(&mut self, offset: usize, buf: &[u8]) -> Option<usize> {
+        let offset = offset as u64;
         match self.seek(SeekFrom::Start(offset)) {
             Ok(real_offset) if real_offset == offset => self.write(buf).ok(),
             _ => None,
@@ -23,6 +26,7 @@ impl Device for File {
 fn test() {
     let file = File::open("sfs.img")
         .expect("failed to open sfs.img");
-    let sfs = SimpleFileSystem::new(Box::new(file))
+    let mut sfs = SimpleFileSystem::new(Box::new(file))
         .expect("failed to create SFS");
+//    let root = sfs.root_inode();
 }

src/vfs.rs

@@ -1,11 +1,13 @@
+use alloc::rc::{Rc, Weak};
+
 /// Abstract operations on a inode.
-pub trait INodeOps {
+pub trait INode {
     fn open(&mut self, flags: u32) -> Result<(), ()>;
     fn close(&mut self) -> Result<(), ()>;
-    fn read(&mut self, buf: &mut [u8]) -> Result<(), ()>;
-    fn write(&mut self, buf: &[u8]) -> Result<(), ()>;
+    fn read_at(&mut self, offset: usize, buf: &mut [u8]) -> Option<usize>;
+    fn write_at(&mut self, offset: usize, buf: &[u8]) -> Option<usize>;
 //    fn fstat(&mut self, buf: &[u8]) -> Result<(), ()>;
-//    fn fsync(&mut self) -> Result<(), ()>;
+    fn sync(&mut self) -> Result<(), ()>;
 //    fn name_file(&mut self) -> Result<(), ()>;
 //    fn reclaim(&mut self) -> Result<(), ()>;
 //    fn get_type(&mut self) -> Result<u32, ()>;
@@ -15,3 +17,12 @@ pub trait INodeOps {
 //    fn loopup(&mut self, path: &'static str) -> Result<(), ()>;
 //    fn io_ctrl(&mut self, op: u32, data: &[u8]) -> Result<(), ()>;
 }
+
+/// Abstract filesystem
+pub trait FileSystem {
+    type INode: INode;
+    fn sync(&mut self) -> Result<(), ()>;
+    fn root_inode(&mut self) -> Rc<Self::INode>;
+    fn unmount(&mut self) -> Result<(), ()>;
+    fn cleanup(&mut self);
+}