500 lines
14 KiB
Rust
500 lines
14 KiB
Rust
use core::mem;
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use core::fmt::{self, Debug};
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use core::nonzero::NonZero;
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use alloc::Vec;
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use error::Error;
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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 as RawInode;
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struct Struct<T, S: Size> {
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pub inner: T,
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pub offset: Address<S>,
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}
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impl<T, S: Size> From<(T, Address<S>)> for Struct<T, S> {
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#[inline]
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fn from((inner, offset): (T, Address<S>)) -> Struct<T, S> {
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Struct { inner, offset }
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}
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}
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/// Safe wrapper for raw sys structs
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pub struct Ext2<S: Size, V: Volume<u8, Address<S>>> {
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volume: V,
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superblock: Struct<Superblock, S>,
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block_groups: Struct<Vec<BlockGroupDescriptor>, S>,
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}
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impl<S: Size, V: Volume<u8, Address<S>>> Ext2<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(volume: V) -> Result<Ext2<S, V>, Error> {
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let superblock = unsafe { Struct::from(Superblock::find(&volume)?) };
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let block_groups_offset = Address::with_block_size(
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superblock.inner.first_data_block + 1,
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0,
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superblock.inner.log_block_size + 10,
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);
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let block_groups_count = superblock
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.inner
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.block_group_count()
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.map(|count| count as usize)
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.map_err(|(a, b)| Error::BadBlockGroupCount(a, b))?;
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let block_groups = unsafe {
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BlockGroupDescriptor::find_descriptor_table(
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&volume,
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block_groups_offset,
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block_groups_count,
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)?
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};
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let block_groups = Struct::from(block_groups);
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Ok(Ext2 {
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volume,
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superblock,
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block_groups,
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})
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}
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#[allow(dead_code)]
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fn update_global(&mut self) -> Result<(), Error> {
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// superblock
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{
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let slice = VolumeSlice::from_cast(
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&self.superblock.inner,
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self.superblock.offset,
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);
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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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// block group descriptors
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let mut offset = self.block_groups.offset;
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for descr in &self.block_groups.inner {
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let slice = VolumeSlice::from_cast(descr, 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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offset =
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offset + Address::from(mem::size_of::<BlockGroupDescriptor>());
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}
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Ok(())
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}
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pub fn read_inode<'a>(
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&'a self,
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buf: &mut [u8],
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inode: &Inode<'a, S, V>,
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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(&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<'a>(
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&'a self,
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_inode: &(Inode<'a, S, V>, 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<'a>(&'a self) -> (Inode<'a, S, V>, Address<S>) {
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self.inode_nth(2).unwrap()
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}
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pub fn inode_nth<'a>(
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&'a self,
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index: usize,
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) -> Option<(Inode<'a, S, V>, Address<S>)> {
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self.inodes_nth(index).next()
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}
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pub fn inodes<'a>(&'a self) -> Inodes<'a, S, V> {
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self.inodes_nth(1)
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}
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pub fn inodes_nth<'a>(&'a self, index: usize) -> Inodes<'a, S, V> {
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assert!(index > 0, "inodes are 1-indexed");
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Inodes {
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fs: self,
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block_groups: &self.block_groups.inner,
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log_block_size: self.log_block_size(),
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inode_size: self.inode_size(),
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inodes_per_group: self.inodes_count(),
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inodes_count: self.total_inodes_count(),
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index,
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}
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}
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}
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impl<S: Size, V: Volume<u8, Address<S>>> Ext2<S, V> {
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fn superblock(&self) -> &Superblock {
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&self.superblock.inner
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}
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#[allow(dead_code)]
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fn superblock_mut(&mut self) -> &mut Superblock {
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&mut self.superblock.inner
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}
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pub fn version(&self) -> (u32, u16) {
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(self.superblock().rev_major, self.superblock().rev_minor)
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}
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pub fn inode_size<'a>(&'a self) -> usize {
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if self.version().0 == 0 {
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mem::size_of::<Inode<'a, S, V>>()
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} else {
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// note: inodes bigger than 128 are not supported
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self.superblock().inode_size as usize
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}
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}
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pub fn inodes_count(&self) -> usize {
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self.superblock().inodes_per_group as _
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}
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pub fn total_inodes_count(&self) -> usize {
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self.superblock().inodes_count as _
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}
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pub fn block_group_count(&self) -> Result<usize, Error> {
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self.superblock()
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.block_group_count()
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.map(|count| count as usize)
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.map_err(|(a, b)| Error::BadBlockGroupCount(a, b))
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}
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pub fn total_block_count(&self) -> usize {
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self.superblock().blocks_count as _
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}
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pub fn free_block_count(&self) -> usize {
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self.superblock().free_blocks_count as _
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}
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pub fn block_size(&self) -> usize {
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self.superblock().block_size()
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}
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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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impl<S: Size, V: Volume<u8, Address<S>>> Debug for Ext2<S, V> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "Ext2<{}>", S::SIZE)
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}
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}
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pub struct Inodes<'a, S: 'a + Size, V: 'a + Volume<u8, Address<S>>> {
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fs: &'a Ext2<S, V>,
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block_groups: &'a [BlockGroupDescriptor],
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log_block_size: u32,
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inode_size: usize,
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inodes_per_group: usize,
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inodes_count: usize,
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index: usize,
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}
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impl<'a, S: Size, V: 'a + Volume<u8, Address<S>>> Iterator for Inodes<'a, 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 = (Inode<'a, S, V>, Address<S>);
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fn next(&mut self) -> Option<Self::Item> {
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if self.index < self.inodes_count {
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let block_group = (self.index - 1) / self.inodes_per_group;
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let index = (self.index - 1) % self.inodes_per_group;
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self.index += 1;
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let inodes_block = self.block_groups[block_group].inode_table_block;
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let offset = Address::with_block_size(
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inodes_block,
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(index * self.inode_size) as i32,
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self.log_block_size,
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);
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let raw = unsafe {
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RawInode::find_inode(&self.fs.volume, offset, self.inode_size)
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.ok()
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};
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raw.map(|(raw, offset)| (Inode::new(self.fs, 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<'a, S: 'a + Size, V: 'a + Volume<u8, Address<S>>> {
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fs: &'a Ext2<S, V>,
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inner: RawInode,
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}
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impl<'a, S: 'a + Size, V: 'a + Volume<u8, Address<S>>> Inode<'a, S, V> {
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pub fn new(fs: &'a Ext2<S, V>, inner: RawInode) -> Inode<'a, S, V> {
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Inode { fs, inner }
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}
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pub fn block(&self, index: usize) -> Option<NonZero<u32>> {
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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.fs.block_size() / 4;
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if index < 12 {
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NonZero::new(self.inner.direct_pointer[index])
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} else if index < bs4 + 12 {
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let block = self.inner.indirect_pointer;
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let offset = index - 12;
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let addr = Address::with_block_size(
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block,
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offset as i32,
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self.fs.log_block_size(),
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);
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let size = Address::from(4_u64);
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let slice = self.fs.volume.slice(addr..addr + size);
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slice.and_then(|slice| unsafe {
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NonZero::new(u32::from_le(slice.dynamic_cast::<u32>().0))
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})
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} else if index < bs4 * bs4 + bs4 + 12 {
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unimplemented!("doubly indirect pointer table");
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} else if index < bs4 * bs4 * bs4 + bs4 * bs4 + bs4 + 12 {
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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, 'b, S: 'a + Size, V: 'a + Volume<u8, Address<S>>>
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{
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inode: &'b Inode<'a, S, V>,
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index: usize,
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}
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impl<'a, 'b, S: Size, V: 'a + Volume<u8, Address<S>>> 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(inode: &'b Inode<'a, S, V>) -> InodeBlocks<'a, 'b, S, V> {
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InodeBlocks { inode, index: 0 }
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}
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}
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impl<'a, 'b, S: Size, 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(
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block,
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0,
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self.inode.fs.log_block_size(),
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)
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..Address::with_block_size(
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block + 1,
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0,
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self.inode.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.inode
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.fs
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.volume
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.slice(block)
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.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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use std::cell::RefCell;
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use sector::{Address, Size512};
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use volume::Volume;
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use super::{Ext2, InodeBlocks};
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#[test]
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fn file_len() {
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let file = RefCell::new(File::open("ext2.img").unwrap());
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assert_eq!(
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Address::<Size512>::from(2048_u64)
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- Address::<Size512>::from(1024_u64),
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Address::<Size512>::new(2, 0)
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);
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assert_eq!(
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unsafe {
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file.slice_unchecked(
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Address::<Size512>::from(1024_u64)
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..Address::<Size512>::from(2048_u64),
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).len()
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},
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1024
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);
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}
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#[test]
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fn file() {
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let file = RefCell::new(File::open("ext2.img").unwrap());
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let fs = Ext2::<Size512, _>::new(file);
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assert!(
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fs.is_ok(),
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"Err({:?})",
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fs.err().unwrap_or_else(|| unreachable!()),
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);
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let fs = fs.unwrap();
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let vers = fs.version();
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println!("version: {}.{}", vers.0, vers.1);
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assert_eq!(128, fs.inode_size());
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}
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#[test]
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fn inodes() {
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let file = RefCell::new(File::open("ext2.img").unwrap());
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let fs = Ext2::<Size512, _>::new(file);
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assert!(
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fs.is_ok(),
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"Err({:?})",
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fs.err().unwrap_or_else(|| unreachable!()),
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);
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let fs = fs.unwrap();
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let inodes = fs.inodes().filter(|inode| inode.0.in_use());
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for inode in inodes {
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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(&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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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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