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#[macro_use]
extern crate bitflags;
extern crate byteorder;
extern crate cast;
extern crate crc;
#[macro_use]
extern crate failure;
use std::collections::HashMap;
use std::io;
use std::io::Read;
use std::io::Seek;
use byteorder::{LittleEndian, ReadBytesExt};
use cast::u64;
use cast::usize;
use failure::Error;
use failure::ResultExt;
mod block_groups;
mod extents;
pub mod parse;
use extents::TreeReader;
#[derive(Debug, Fail)]
pub enum ParseError {
#[fail(display = "assumption failed: {}", reason)]
AssumptionFailed { reason: String },
#[fail(display = "filesystem uses an unsupported feature: {}", reason)]
UnsupportedFeature { reason: String },
#[fail(display = "filesystem uses an unsupported feature: {}", reason)]
NotFound { reason: String },
}
fn assumption_failed<S: ToString>(reason: S) -> ParseError {
ParseError::AssumptionFailed {
reason: reason.to_string(),
}
}
fn unsupported_feature<S: ToString>(reason: S) -> ParseError {
ParseError::UnsupportedFeature {
reason: reason.to_string(),
}
}
fn not_found<S: ToString>(reason: S) -> ParseError {
ParseError::NotFound {
reason: reason.to_string(),
}
}
bitflags! {
pub struct InodeFlags: u32 {
const SECRM = 0x0000_0001;
const UNRM = 0x0000_0002;
const COMPR = 0x0000_0004;
const SYNC = 0x0000_0008;
const IMMUTABLE = 0x0000_0010;
const APPEND = 0x0000_0020;
const NODUMP = 0x0000_0040;
const NOATIME = 0x0000_0080;
const DIRTY = 0x0000_0100;
const COMPRBLK = 0x0000_0200;
const NOCOMPR = 0x0000_0400;
const ENCRYPT = 0x0000_0800;
const INDEX = 0x0000_1000;
const IMAGIC = 0x0000_2000;
const JOURNAL_DATA = 0x0000_4000;
const NOTAIL = 0x0000_8000;
const DIRSYNC = 0x0001_0000;
const TOPDIR = 0x0002_0000;
const HUGE_FILE = 0x0004_0000;
const EXTENTS = 0x0008_0000;
const EA_INODE = 0x0020_0000;
const EOFBLOCKS = 0x0040_0000;
const INLINE_DATA = 0x1000_0000;
const PROJINHERIT = 0x2000_0000;
const RESERVED = 0x8000_0000;
}
}
#[derive(Debug, PartialEq)]
pub enum FileType {
RegularFile,
SymbolicLink,
CharacterDevice,
BlockDevice,
Directory,
Fifo,
Socket,
}
#[derive(Debug)]
pub enum Enhanced {
RegularFile,
SymbolicLink(String),
CharacterDevice(u16, u32),
BlockDevice(u16, u32),
Directory(Vec<DirEntry>),
Fifo,
Socket,
}
impl FileType {
fn from_mode(mode: u16) -> Option<FileType> {
match mode >> 12 {
0x1 => Some(FileType::Fifo),
0x2 => Some(FileType::CharacterDevice),
0x4 => Some(FileType::Directory),
0x6 => Some(FileType::BlockDevice),
0x8 => Some(FileType::RegularFile),
0xA => Some(FileType::SymbolicLink),
0xC => Some(FileType::Socket),
_ => None,
}
}
fn from_dir_hint(hint: u8) -> Option<FileType> {
match hint {
1 => Some(FileType::RegularFile),
2 => Some(FileType::Directory),
3 => Some(FileType::CharacterDevice),
4 => Some(FileType::BlockDevice),
5 => Some(FileType::Fifo),
6 => Some(FileType::Socket),
7 => Some(FileType::SymbolicLink),
_ => None,
}
}
}
#[derive(Debug)]
pub struct DirEntry {
pub inode: u32,
pub file_type: FileType,
pub name: String,
}
#[derive(Debug)]
pub struct Stat {
pub extracted_type: FileType,
pub file_mode: u16,
pub uid: u32,
pub gid: u32,
pub size: u64,
pub atime: Time,
pub ctime: Time,
pub mtime: Time,
pub btime: Option<Time>,
pub link_count: u16,
pub xattrs: HashMap<String, Vec<u8>>,
}
const INODE_CORE_SIZE: usize = 4 * 15;
pub struct Inode {
pub stat: Stat,
pub number: u32,
flags: InodeFlags,
checksum_prefix: Option<u32>,
core: [u8; INODE_CORE_SIZE],
block_size: u32,
}
#[derive(Debug)]
pub struct SuperBlock<R> {
inner: R,
load_xattrs: bool,
uuid_checksum: Option<u32>,
groups: block_groups::BlockGroups,
}
#[derive(Debug)]
pub struct Time {
pub epoch_secs: u32,
pub nanos: Option<u32>,
}
#[derive(Debug, PartialEq)]
pub enum Checksums {
Required,
Enabled,
}
impl Default for Checksums {
fn default() -> Self {
Checksums::Required
}
}
#[derive(Debug, Default)]
pub struct Options {
pub checksums: Checksums,
}
impl<R> SuperBlock<R>
where
R: io::Read + io::Seek,
{
pub fn new(inner: R) -> Result<SuperBlock<R>, Error> {
SuperBlock::new_with_options(inner, &Options::default())
}
pub fn new_with_options(mut inner: R, options: &Options) -> Result<SuperBlock<R>, Error> {
inner.seek(io::SeekFrom::Start(1024))?;
Ok(parse::superblock(inner, options)
.with_context(|_| format_err!("failed to parse superblock"))?)
}
pub fn load_inode(&mut self, inode: u32) -> Result<Inode, Error> {
let data = self
.load_inode_bytes(inode)
.with_context(|_| format_err!("failed to find inode <{}> on disc", inode))?;
let uuid_checksum = self.uuid_checksum;
let parsed = parse::inode(
data,
|block| self.load_disc_bytes(block),
uuid_checksum,
inode,
).with_context(|_| format_err!("failed to parse inode <{}>", inode))?;
Ok(Inode {
number: inode,
stat: parsed.stat,
flags: parsed.flags,
core: parsed.core,
checksum_prefix: parsed.checksum_prefix,
block_size: self.groups.block_size,
})
}
fn load_inode_bytes(&mut self, inode: u32) -> Result<Vec<u8>, Error> {
self.inner
.seek(io::SeekFrom::Start(self.groups.index_of(inode)?))?;
let mut data = vec![0u8; self.groups.inode_size as usize];
self.inner.read_exact(&mut data)?;
Ok(data)
}
fn load_disc_bytes(&mut self, block: u64) -> Result<Vec<u8>, Error> {
load_disc_bytes(&mut self.inner, self.groups.block_size, block)
}
pub fn root(&mut self) -> Result<Inode, Error> {
Ok(self
.load_inode(2)
.with_context(|_| format_err!("failed to load root inode"))?)
}
pub fn walk<F>(&mut self, inode: &Inode, path: &str, visit: &mut F) -> Result<bool, Error>
where
F: FnMut(&mut Self, &str, &Inode, &Enhanced) -> Result<bool, Error>,
{
let enhanced = inode.enhance(&mut self.inner)?;
if !visit(self, path, inode, &enhanced)
.with_context(|_| format_err!("user closure failed"))?
{
return Ok(false);
}
if let Enhanced::Directory(entries) = enhanced {
for entry in entries {
if "." == entry.name || ".." == entry.name {
continue;
}
let child_node = self.load_inode(entry.inode).with_context(|_| {
format_err!("loading {} ({:?})", entry.name, entry.file_type)
})?;
if !self
.walk(&child_node, &format!("{}/{}", path, entry.name), visit)
.with_context(|_| format_err!("processing '{}'", entry.name))?
{
return Ok(false);
}
}
}
Ok(true)
}
pub fn resolve_path(&mut self, path: &str) -> Result<DirEntry, Error> {
let path = path.trim_right_matches('/');
if path.is_empty() {
return Ok(DirEntry {
inode: 2,
file_type: FileType::Directory,
name: "/".to_string(),
});
}
let mut curr = self.root()?;
let mut parts = path.split('/').collect::<Vec<&str>>();
let last = parts.pop().unwrap();
for part in parts {
if part.is_empty() {
continue;
}
let child_inode = self.dir_entry_named(&curr, part)?.inode;
curr = self.load_inode(child_inode)?;
}
self.dir_entry_named(&curr, last)
}
fn dir_entry_named(&mut self, inode: &Inode, name: &str) -> Result<DirEntry, Error> {
if let Enhanced::Directory(entries) = self.enhance(inode)? {
if let Some(en) = entries.into_iter().find(|entry| entry.name == name) {
Ok(en)
} else {
Err(not_found(format!("component {} isn't there", name)).into())
}
} else {
Err(not_found(format!("component {} isn't a directory", name)).into())
}
}
pub fn open(&mut self, inode: &Inode) -> Result<TreeReader<&mut R>, Error> {
inode.reader(&mut self.inner)
}
pub fn enhance(&mut self, inode: &Inode) -> Result<Enhanced, Error> {
inode.enhance(&mut self.inner)
}
}
fn load_disc_bytes<R>(mut inner: R, block_size: u32, block: u64) -> Result<Vec<u8>, Error>
where
R: io::Read + io::Seek,
{
inner.seek(io::SeekFrom::Start(block as u64 * u64::from(block_size)))?;
let mut data = vec![0u8; block_size as usize];
inner.read_exact(&mut data)?;
Ok(data)
}
impl Inode {
fn reader<R>(&self, inner: R) -> Result<TreeReader<R>, Error>
where
R: io::Read + io::Seek,
{
Ok(TreeReader::new(
inner,
self.block_size,
self.stat.size,
self.core,
self.checksum_prefix,
).with_context(|_| format_err!("opening inode <{}>", self.number))?)
}
fn enhance<R>(&self, inner: R) -> Result<Enhanced, Error>
where
R: io::Read + io::Seek,
{
Ok(match self.stat.extracted_type {
FileType::RegularFile => Enhanced::RegularFile,
FileType::Socket => Enhanced::Socket,
FileType::Fifo => Enhanced::Fifo,
FileType::Directory => Enhanced::Directory(self.read_directory(inner)?),
FileType::SymbolicLink => {
Enhanced::SymbolicLink(if self.stat.size < u64(INODE_CORE_SIZE) {
ensure!(
self.flags.is_empty(),
unsupported_feature(format!(
"symbolic links may not have flags: {:?}",
self.flags
))
);
std::str::from_utf8(&self.core[0..self.stat.size as usize])
.with_context(|_| format_err!("short symlink is invalid utf-8"))?
.to_string()
} else {
ensure!(
self.only_relevant_flag_is_extents(),
unsupported_feature(format!(
"symbolic links may not have non-extent flags: {:?}",
self.flags
))
);
std::str::from_utf8(&self.load_all(inner)?)
.with_context(|_| format_err!("long symlink is invalid utf-8"))?
.to_string()
})
}
FileType::CharacterDevice => {
let (maj, min) = load_maj_min(self.core);
Enhanced::CharacterDevice(maj, min)
}
FileType::BlockDevice => {
let (maj, min) = load_maj_min(self.core);
Enhanced::BlockDevice(maj, min)
}
})
}
fn load_all<R>(&self, inner: R) -> Result<Vec<u8>, Error>
where
R: io::Read + io::Seek,
{
let size = usize_check(self.stat.size)?;
let mut ret = vec![0u8; size];
self.reader(inner)?.read_exact(&mut ret)?;
Ok(ret)
}
fn read_directory<R>(&self, inner: R) -> Result<Vec<DirEntry>, Error>
where
R: io::Read + io::Seek,
{
let mut dirs = Vec::with_capacity(40);
let data = {
ensure!(
self.only_relevant_flag_is_extents(),
unsupported_feature(format!(
"inode with unsupported flags: {0:x} {0:b}",
self.flags
))
);
self.load_all(inner)?
};
let total_len = data.len();
let mut cursor = io::Cursor::new(data);
let mut read = 0usize;
loop {
let child_inode = cursor.read_u32::<LittleEndian>()?;
let rec_len = cursor.read_u16::<LittleEndian>()?;
ensure!(
rec_len > 8,
unsupported_feature(format!(
"directory record length is too short, {} must be > 8",
rec_len
))
);
let name_len = cursor.read_u8()?;
let file_type = cursor.read_u8()?;
let mut name = vec![0u8; name_len as usize];
cursor.read_exact(&mut name)?;
if 0 != child_inode {
let name = std::str::from_utf8(&name)
.map_err(|e| parse_error(format!("invalid utf-8 in file name: {}", e)))?;
dirs.push(DirEntry {
inode: child_inode,
name: name.to_string(),
file_type: FileType::from_dir_hint(file_type).ok_or_else(|| {
unsupported_feature(format!(
"unexpected file type in directory: {}",
file_type
))
})?,
});
} else if 12 == rec_len && 0 == name_len && 0xDE == file_type {
if let Some(checksum_prefix) = self.checksum_prefix {
let expected = cursor.read_u32::<LittleEndian>()?;
let computed =
parse::ext4_style_crc32c_le(checksum_prefix, &cursor.into_inner()[0..read]);
ensure!(
expected == computed,
assumption_failed(format!(
"directory checksum mismatch: on-disk: {:08x}, computed: {:08x}",
expected, computed
))
);
}
break;
}
cursor.seek(io::SeekFrom::Current(
i64::from(rec_len) - i64::from(name_len) - 4 - 2 - 1 - 1,
))?;
read += rec_len as usize;
if read >= total_len {
ensure!(
read == total_len,
assumption_failed(format!("short read, {} != {}", read, total_len))
);
ensure!(
self.checksum_prefix.is_none(),
assumption_failed(
"directory checksums are enabled but checksum record not found"
)
);
break;
}
}
Ok(dirs)
}
fn only_relevant_flag_is_extents(&self) -> bool {
self.flags
& (InodeFlags::COMPR
| InodeFlags::DIRTY
| InodeFlags::COMPRBLK
| InodeFlags::ENCRYPT
| InodeFlags::IMAGIC
| InodeFlags::NOTAIL
| InodeFlags::TOPDIR
| InodeFlags::HUGE_FILE
| InodeFlags::EXTENTS
| InodeFlags::EA_INODE
| InodeFlags::EOFBLOCKS
| InodeFlags::INLINE_DATA) == InodeFlags::EXTENTS
}
}
fn load_maj_min(core: [u8; INODE_CORE_SIZE]) -> (u16, u32) {
if 0 != core[0] || 0 != core[1] {
(u16::from(core[1]), u32::from(core[0]))
} else {
(
u16::from(core[5]) | (u16::from(core[6] & 0b0000_1111) << 8),
u32::from(core[4])
| (u32::from(core[7]) << 12)
| (u32::from(core[6] & 0b1111_0000) >> 4) << 8,
)
}
}
#[inline]
fn read_le16(from: &[u8]) -> u16 {
use byteorder::ByteOrder;
LittleEndian::read_u16(from)
}
#[inline]
fn read_le32(from: &[u8]) -> u32 {
use byteorder::ByteOrder;
LittleEndian::read_u32(from)
}
fn parse_error(msg: String) -> Error {
assumption_failed(msg).into()
}
#[allow(unknown_lints, absurd_extreme_comparisons)]
pub fn usize_check(val: u64) -> Result<usize, Error> {
ensure!(
val <= u64(std::usize::MAX),
assumption_failed(format!(
"value is too big for memory on this platform: {}",
val
))
);
Ok(usize(val))
}