add an `InodeBlocks` `Iterator` for iterating over the blocks of an inode
Szymon Walter
parent
83a9d706a3
commit
30aed8bde7
220
src/fs.rs
220
src/fs.rs
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@ -1,5 +1,6 @@
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use core::mem;
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use core::marker::PhantomData;
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use core::nonzero::NonZero;
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use alloc::Vec;
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@ -8,7 +9,7 @@ use sector::{Address, Size};
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use volume::{Volume, VolumeSlice};
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use sys::superblock::Superblock;
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use sys::block_group::BlockGroupDescriptor;
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use sys::inode::Inode;
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use sys::inode::Inode as RawInode;
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struct Struct<T, S: Size> {
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pub inner: T,
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@ -90,11 +91,41 @@ where
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&mut self,
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&(ref inode, offset): &(Inode, Address<S>),
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) -> Result<(), Error> {
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let slice = VolumeSlice::from_cast(inode, offset);
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let slice = VolumeSlice::from_cast(&inode.inner, offset);
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let commit = slice.commit();
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self.volume.commit(commit).map_err(|err| Error::from(err))
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}
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pub fn read_inode(
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&self,
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buf: &mut [u8],
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inode: &Inode,
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) -> Result<usize, Error> {
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let total_size = inode.size();
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let mut read_size = 0;
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let block_size = self.block_size();
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let offset = 0;
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for (data, _) in InodeBlocks::new(self, &inode) {
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let data_size = block_size
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.min(total_size - read_size)
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.min(buf.len() - offset);
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let end = offset + data_size;
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buf[offset..end].copy_from_slice(&data[..data_size]);
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read_size += data_size;
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}
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Ok(read_size)
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}
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pub fn write_inode(
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&self,
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&(ref inode, offset): &(Inode, Address<S>),
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buf: &[u8],
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) -> Result<usize, Error> {
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unimplemented!()
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}
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pub fn root_inode(&self) -> (Inode, Address<S>) {
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self.inode_nth(2).unwrap()
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}
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@ -173,6 +204,14 @@ where
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pub fn log_block_size(&self) -> u32 {
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self.superblock().log_block_size + 10
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}
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pub fn sector_size(&self) -> usize {
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S::SIZE
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}
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pub fn log_sector_size(&self) -> u32 {
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S::LOG_SIZE
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}
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}
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pub struct Inodes<'a, S: Size, V: 'a + Volume<u8, Address<S>>> {
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@ -204,18 +243,141 @@ where
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let offset = Address::with_block_size(
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inodes_block,
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index * self.inode_size,
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(index * self.inode_size) as isize,
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self.log_block_size,
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);
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unsafe {
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Inode::find_inode(self.volume, offset, self.inode_size).ok()
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}
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let raw = unsafe {
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RawInode::find_inode(self.volume, offset, self.inode_size).ok()
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};
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raw.map(|(raw, offset)| (Inode::new(raw), offset))
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} else {
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None
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}
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}
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}
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#[derive(Debug, Clone)]
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pub struct Inode {
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inner: RawInode,
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}
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impl Inode {
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pub fn new(inner: RawInode) -> Inode {
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Inode { inner }
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}
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pub fn block(&self, index: usize) -> Option<NonZero<usize>> {
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// number of blocks in direct table: 12
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// number of blocks in indirect table: block_size/4
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// why?
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// - a block is n bytes long
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// - a block address occupies 32 bits, or 4 bytes
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// - thus, n/4
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// number of blocks in doubly table: (block_size/4)^2
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// why?
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// - every entry in the doubly table points to another block
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// - that's n/4 blocks, where n is the block size
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// - every block contains n/4 block pointers
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// - that's n/4 blocks with n/4 pointers each = (n/4)^2
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// number of blocks in triply table: (block_size/4)^3
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let bs4 = self.block_size() / 4;
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if index < 12 {
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NonZero::new(self.inner.direct_pointer[index] as usize)
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} else if index < bs4 {
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unimplemented!("indirect pointer table");
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} else if index < bs4 * bs4 {
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unimplemented!("doubly indirect pointer table");
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} else if index < bs4 * bs4 * bs4 {
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unimplemented!("triply indirect pointer table");
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} else {
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None
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}
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}
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pub fn in_use(&self) -> bool {
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self.inner.hard_links > 0
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}
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pub fn uid(&self) -> u16 {
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self.inner.uid
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}
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pub fn sectors(&self) -> usize {
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self.inner.sectors_count as usize
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}
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pub fn size32(&self) -> u32 {
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self.inner.size_low
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}
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pub fn size64(&self) -> u64 {
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self.inner.size_low as u64 | (self.inner.size_high as u64) << 32
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}
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#[cfg(target_pointer_width = "64")]
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#[inline]
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pub fn size(&self) -> usize {
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self.size64() as usize
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}
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#[cfg(target_pointer_width = "32")]
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#[inline]
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pub fn size(&self) -> usize {
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self.size32() as usize
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}
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}
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pub struct InodeBlocks<'a, 'b, S: 'a + Size, V: 'a + Volume<u8, Address<S>>> {
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fs: &'a Ext2<S, V>,
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inode: &'b Inode,
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index: usize,
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}
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impl<'a, 'b, S: Size + Copy, V: 'a + Volume<u8, Address<S>>>
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InodeBlocks<'a, 'b, S, V>
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where
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Error: From<V::Error>,
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{
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pub fn new(
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fs: &'a Ext2<S, V>,
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inode: &'b Inode,
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) -> InodeBlocks<'a, 'b, S, V> {
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InodeBlocks {
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fs: fs,
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inode,
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index: 0,
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}
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}
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}
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impl<'a, 'b, S: Size + Copy, V: 'a + Volume<u8, Address<S>>> Iterator
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for InodeBlocks<'a, 'b, S, V>
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where
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Error: From<V::Error>,
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{
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type Item = (VolumeSlice<'a, u8, Address<S>>, Address<S>);
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fn next(&mut self) -> Option<Self::Item> {
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let block = self.inode.block(self.index);
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block
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.map(|block| {
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let block = block.get();
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self.index += 1;
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Address::with_block_size(block, 0, self.fs.log_block_size())
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..Address::with_block_size(
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block + 1,
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0,
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self.fs.log_block_size(),
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)
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})
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.and_then(|block| {
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let offset = block.start;
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self.fs.volume.slice(block).map(|slice| (slice, offset))
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})
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}
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}
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#[cfg(test)]
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mod tests {
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use std::fs::File;
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@ -224,7 +386,7 @@ mod tests {
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use sector::{Address, Size512};
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use volume::Volume;
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use super::Ext2;
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use super::{Ext2, InodeBlocks};
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#[test]
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fn file_len() {
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@ -281,4 +443,48 @@ mod tests {
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println!("{:?}", inode);
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}
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}
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#[test]
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fn inode_blocks() {
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use std::str;
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let file = RefCell::new(File::open("ext2.img").unwrap());
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let fs = Ext2::<Size512, _>::new(file).unwrap();
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let inodes = fs.inodes().filter(|inode| {
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inode.0.in_use() && inode.0.uid() == 1000 && inode.0.size() < 1024
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});
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for inode in inodes {
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println!("{:?}", inode.0);
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let size = inode.0.size();
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for block in InodeBlocks::new(&fs, &inode.0) {
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let (data, _) = block;
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assert_eq!(data.len(), fs.block_size());
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println!("{:?}", &data[..size]);
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let _ = str::from_utf8(&data[..size])
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.map(|string| println!("{}", string));
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}
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}
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}
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#[test]
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fn read_inode() {
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use std::str;
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let file = RefCell::new(File::open("ext2.img").unwrap());
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let fs = Ext2::<Size512, _>::new(file).unwrap();
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let inodes = fs.inodes().filter(|inode| {
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inode.0.in_use() && inode.0.uid() == 1000 && inode.0.size() < 1024
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});
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for (inode, _) in inodes {
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let mut buf = Vec::with_capacity(inode.size());
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unsafe {
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buf.set_len(inode.size());
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}
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let size = fs.read_inode(&mut buf[..], &inode);
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assert_eq!(size, Ok(inode.size()));
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unsafe {
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buf.set_len(size.unwrap());
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}
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}
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}
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}
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@ -4,6 +4,7 @@
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#![feature(macro_lifetime_matcher)]
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#![feature(const_fn)]
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#![feature(step_trait)]
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#![feature(nonzero)]
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#![cfg_attr(all(not(test), feature = "no_std"), no_std)]
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#[macro_use]
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