562 lines
18 KiB
Rust
562 lines
18 KiB
Rust
//! *pxar* format decoder.
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//!
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//! This module contain the code to decode *pxar* archive files.
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use failure::*;
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use endian_trait::Endian;
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use super::format_definition::*;
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use std::io::{Read, Write};
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use std::path::{Path, PathBuf};
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use std::os::unix::io::AsRawFd;
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use std::os::unix::io::RawFd;
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use std::os::unix::io::FromRawFd;
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use std::os::unix::ffi::{OsStringExt};
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use std::ffi::{OsStr, OsString};
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use nix::fcntl::OFlag;
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use nix::sys::stat::Mode;
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use nix::errno::Errno;
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use nix::NixPath;
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// This one need Read, but works without Seek
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pub struct PxarDecoder<'a, R: Read> {
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reader: &'a mut R,
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skip_buffer: Vec<u8>,
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}
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const HEADER_SIZE: u64 = std::mem::size_of::<CaFormatHeader>() as u64;
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impl <'a, R: Read> PxarDecoder<'a, R> {
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pub fn new(reader: &'a mut R) -> Self {
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let mut skip_buffer = vec![0u8; 64*1024];
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Self { reader, skip_buffer }
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}
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fn read_item<T: Endian>(&mut self) -> Result<T, Error> {
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let mut result: T = unsafe { std::mem::uninitialized() };
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let buffer = unsafe { std::slice::from_raw_parts_mut(
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&mut result as *mut T as *mut u8,
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std::mem::size_of::<T>()
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)};
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self.reader.read_exact(buffer)?;
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Ok(result.from_le())
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}
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fn read_symlink(&mut self, size: u64) -> Result<PathBuf, Error> {
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if size < (HEADER_SIZE + 2) {
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bail!("dectected short symlink target.");
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}
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let target_len = size - HEADER_SIZE;
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if target_len > (libc::PATH_MAX as u64) {
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bail!("symlink target too long ({}).", target_len);
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}
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let mut buffer = vec![0u8; target_len as usize];
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self.reader.read_exact(&mut buffer)?;
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let last_byte = buffer.pop().unwrap();
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if last_byte != 0u8 {
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bail!("symlink target not nul terminated.");
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}
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Ok(PathBuf::from(std::ffi::OsString::from_vec(buffer)))
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}
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fn read_filename(&mut self, size: u64) -> Result<OsString, Error> {
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if size < (HEADER_SIZE + 2) {
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bail!("dectected short filename");
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}
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let name_len = size - HEADER_SIZE;
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if name_len > ((libc::FILENAME_MAX as u64) + 1) {
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bail!("filename too long ({}).", name_len);
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}
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let mut buffer = vec![0u8; name_len as usize];
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self.reader.read_exact(&mut buffer)?;
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let last_byte = buffer.pop().unwrap();
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if last_byte != 0u8 {
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bail!("filename entry not nul terminated.");
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}
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if (buffer.len() == 1 && buffer[0] == b'.') || (buffer.len() == 2 && buffer[0] == b'.' && buffer[1] == b'.') {
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bail!("found invalid filename with slashes.");
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}
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if buffer.iter().find(|b| (**b == b'/')).is_some() {
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bail!("found invalid filename with slashes.");
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}
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let name = std::ffi::OsString::from_vec(buffer);
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if name.is_empty() {
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bail!("found empty filename.");
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}
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Ok(name)
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}
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fn restore_attributes(&mut self, _entry: &CaFormatEntry) -> Result<CaFormatHeader, Error> {
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loop {
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let head: CaFormatHeader = self.read_item()?;
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match head.htype {
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// fimxe: impl ...
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_ => return Ok(head),
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}
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}
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}
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fn restore_mode(&mut self, entry: &CaFormatEntry, fd: RawFd) -> Result<(), Error> {
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let mode = Mode::from_bits_truncate((entry.mode as u32) & 0o7777);
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nix::sys::stat::fchmod(fd, mode)?;
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Ok(())
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}
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fn restore_mode_at(&mut self, entry: &CaFormatEntry, dirfd: RawFd, filename: &OsStr) -> Result<(), Error> {
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let mode = Mode::from_bits_truncate((entry.mode as u32) & 0o7777);
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// NOTE: we want :FchmodatFlags::NoFollowSymlink, but fchmodat does not support that
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// on linux (see man fchmodat). Fortunately, we can simply avoid calling this on symlinks.
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nix::sys::stat::fchmodat(Some(dirfd), filename, mode, nix::sys::stat::FchmodatFlags::FollowSymlink)?;
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Ok(())
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}
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fn restore_ugid(&mut self, entry: &CaFormatEntry, fd: RawFd) -> Result<(), Error> {
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let uid = entry.uid as u32;
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let gid = entry.gid as u32;
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let res = unsafe { libc::fchown(fd, uid, gid) };
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Errno::result(res)?;
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Ok(())
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}
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fn restore_ugid_at(&mut self, entry: &CaFormatEntry, dirfd: RawFd, filename: &OsStr) -> Result<(), Error> {
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let uid = entry.uid as u32;
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let gid = entry.gid as u32;
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let res = filename.with_nix_path(|cstr| unsafe {
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libc::fchownat(dirfd, cstr.as_ptr(), uid, gid, libc::AT_SYMLINK_NOFOLLOW)
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})?;
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Errno::result(res)?;
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Ok(())
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}
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fn restore_mtime(&mut self, entry: &CaFormatEntry, fd: RawFd) -> Result<(), Error> {
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let times = nsec_to_update_timespec(entry.mtime);
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let res = unsafe { libc::futimens(fd, ×[0]) };
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Errno::result(res)?;
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Ok(())
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}
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fn restore_mtime_at(&mut self, entry: &CaFormatEntry, dirfd: RawFd, filename: &OsStr) -> Result<(), Error> {
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let times = nsec_to_update_timespec(entry.mtime);
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let res = filename.with_nix_path(|cstr| unsafe {
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libc::utimensat(dirfd, cstr.as_ptr(), ×[0], libc::AT_SYMLINK_NOFOLLOW)
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})?;
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Errno::result(res)?;
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Ok(())
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}
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fn restore_device_at(&mut self, entry: &CaFormatEntry, dirfd: RawFd, filename: &OsStr, device: &CaFormatDevice) -> Result<(), Error> {
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let rdev = nix::sys::stat::makedev(device.major, device.minor);
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let mode = ((entry.mode as u32) & libc::S_IFMT) | 0o0600;
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let res = filename.with_nix_path(|cstr| unsafe {
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libc::mknodat(dirfd, cstr.as_ptr(), mode, rdev)
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})?;
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Errno::result(res)?;
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Ok(())
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}
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fn restore_socket_at(&mut self, dirfd: RawFd, filename: &OsStr) -> Result<(), Error> {
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let mode = libc::S_IFSOCK | 0o0600;
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let res = filename.with_nix_path(|cstr| unsafe {
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libc::mknodat(dirfd, cstr.as_ptr(), mode, 0)
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})?;
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Errno::result(res)?;
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Ok(())
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}
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fn restore_fifo_at(&mut self, dirfd: RawFd, filename: &OsStr) -> Result<(), Error> {
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let mode = libc::S_IFIFO | 0o0600;
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let res = filename.with_nix_path(|cstr| unsafe {
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libc::mkfifoat(dirfd, cstr.as_ptr(), mode)
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})?;
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Errno::result(res)?;
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Ok(())
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}
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fn skip_bytes(&mut self, count: usize) -> Result<(), Error> {
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let mut done = 0;
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while done < count {
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let todo = count - done;
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let n = if todo > self.skip_buffer.len() { self.skip_buffer.len() } else { todo };
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let data = &mut self.skip_buffer[..n];
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self.reader.read_exact(data)?;
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done += n;
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}
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Ok(())
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}
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pub fn restore<F>(
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&mut self,
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path: &Path, // used for error reporting
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callback: &F,
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) -> Result<(), Error>
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where F: Fn(&Path) -> Result<(), Error>
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{
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let _ = std::fs::create_dir(path);
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let dir = match nix::dir::Dir::open(path, nix::fcntl::OFlag::O_DIRECTORY, nix::sys::stat::Mode::empty()) {
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Ok(dir) => dir,
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Err(err) => bail!("unable to open target directory {:?} - {}", path, err),
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};
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self.restore_sequential(&mut path.to_owned(), &OsString::new(), &dir, callback)
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}
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fn restore_sequential<F>(
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&mut self,
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path: &mut PathBuf, // used for error reporting
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filename: &OsStr, // repeats path last component
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parent: &nix::dir::Dir,
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callback: &F,
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) -> Result<(), Error>
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where F: Fn(&Path) -> Result<(), Error>
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{
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let parent_fd = parent.as_raw_fd();
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// read ENTRY first
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let head: CaFormatHeader = self.read_item()?;
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check_ca_header::<CaFormatEntry>(&head, CA_FORMAT_ENTRY)?;
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let entry: CaFormatEntry = self.read_item()?;
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let mode = entry.mode as u32; //fixme: upper 32bits?
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let ifmt = mode & libc::S_IFMT;
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if ifmt == libc::S_IFDIR {
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let dir;
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if filename.is_empty() {
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dir = nix::dir::Dir::openat(parent_fd, ".", OFlag::O_DIRECTORY, Mode::empty())?;
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} else {
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dir = match dir_mkdirat(parent_fd, filename, true) {
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Ok(dir) => dir,
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Err(err) => bail!("unable to open directory {:?} - {}", path, err),
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};
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}
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let mut head = self.restore_attributes(&entry)?;
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while head.htype == CA_FORMAT_FILENAME {
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let name = self.read_filename(head.size)?;
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path.push(&name);
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println!("NAME: {:?}", path);
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self.restore_sequential(path, &name, &dir, callback)?;
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path.pop();
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head = self.read_item()?;
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}
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if head.htype != CA_FORMAT_GOODBYE {
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bail!("got unknown header type inside directory entry {:016x}", head.htype);
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}
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println!("Skip Goodbye");
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if head.size < HEADER_SIZE { bail!("detected short goodbye table"); }
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self.skip_bytes((head.size - HEADER_SIZE) as usize)?;
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self.restore_mode(&entry, dir.as_raw_fd())?;
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self.restore_mtime(&entry, dir.as_raw_fd())?;
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self.restore_ugid(&entry, dir.as_raw_fd())?;
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return Ok(());
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}
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if filename.is_empty() {
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bail!("got empty file name at {:?}", path)
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}
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if ifmt == libc::S_IFLNK {
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// fixme: create symlink
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//fixme: restore permission, acls, xattr, ...
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let head: CaFormatHeader = self.read_item()?;
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match head.htype {
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CA_FORMAT_SYMLINK => {
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let target = self.read_symlink(head.size)?;
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println!("TARGET: {:?}", target);
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if let Err(err) = symlinkat(&target, parent_fd, filename) {
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bail!("create symlink {:?} failed - {}", path, err);
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}
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}
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_ => {
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bail!("got unknown header type inside symlink entry {:016x}", head.htype);
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}
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}
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// self.restore_mode_at(&entry, parent_fd, filename)?; //not supported on symlinks
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self.restore_ugid_at(&entry, parent_fd, filename)?;
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self.restore_mtime_at(&entry, parent_fd, filename)?;
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return Ok(());
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}
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if ifmt == libc::S_IFSOCK {
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self.restore_socket_at(parent_fd, filename)?;
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self.restore_mode_at(&entry, parent_fd, filename)?;
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self.restore_ugid_at(&entry, parent_fd, filename)?;
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self.restore_mtime_at(&entry, parent_fd, filename)?;
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return Ok(());
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}
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if ifmt == libc::S_IFIFO {
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self.restore_fifo_at(parent_fd, filename)?;
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self.restore_mode_at(&entry, parent_fd, filename)?;
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self.restore_ugid_at(&entry, parent_fd, filename)?;
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self.restore_mtime_at(&entry, parent_fd, filename)?;
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return Ok(());
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}
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if (ifmt == libc::S_IFBLK) || (ifmt == libc::S_IFCHR) {
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let head: CaFormatHeader = self.read_item()?;
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match head.htype {
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CA_FORMAT_DEVICE => {
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let device: CaFormatDevice = self.read_item()?;
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self.restore_device_at(&entry, parent_fd, filename, &device)?;
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}
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_ => {
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bail!("got unknown header type inside device entry {:016x}", head.htype);
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}
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}
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self.restore_mode_at(&entry, parent_fd, filename)?;
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self.restore_ugid_at(&entry, parent_fd, filename)?;
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self.restore_mtime_at(&entry, parent_fd, filename)?;
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return Ok(());
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}
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if ifmt == libc::S_IFREG {
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let mut read_buffer: [u8; 64*1024] = unsafe { std::mem::uninitialized() };
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let flags = OFlag::O_CREAT|OFlag::O_WRONLY|OFlag::O_EXCL;
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let open_mode = Mode::from_bits_truncate(0o0600 | mode);
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let mut file = match file_openat(parent_fd, filename, flags, open_mode) {
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Ok(file) => file,
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Err(err) => bail!("open file {:?} failed - {}", path, err),
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};
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let head = self.restore_attributes(&entry)?;
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if head.htype != CA_FORMAT_PAYLOAD {
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bail!("got unknown header type for file entry {:016x}", head.htype);
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}
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if head.size < HEADER_SIZE {
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bail!("detected short payload");
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}
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let need = (head.size - HEADER_SIZE) as usize;
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//self.reader.seek(SeekFrom::Current(need as i64))?;
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let mut done = 0;
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while done < need {
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let todo = need - done;
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let n = if todo > read_buffer.len() { read_buffer.len() } else { todo };
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let data = &mut read_buffer[..n];
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self.reader.read_exact(data)?;
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file.write_all(data)?;
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done += n;
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}
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self.restore_mode(&entry, file.as_raw_fd())?;
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self.restore_mtime(&entry, file.as_raw_fd())?;
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self.restore_ugid(&entry, file.as_raw_fd())?;
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return Ok(());
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}
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Ok(())
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}
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/// Dump archive format details. This is ment for debugging.
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pub fn dump_archive<W: std::io::Write>(
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&mut self,
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output: &mut W,
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) -> Result<(), Error> {
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let mut nesting = 0;
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let mut dirpath = PathBuf::new();
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let head: CaFormatHeader = self.read_item()?;
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check_ca_header::<CaFormatEntry>(&head, CA_FORMAT_ENTRY)?;
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let entry: CaFormatEntry = self.read_item()?;
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println!("Root: {:08x} {:08x}", entry.mode, (entry.mode as u32) & libc::S_IFDIR);
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loop {
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let head: CaFormatHeader = self.read_item()?;
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println!("Type: {:016x}", head.htype);
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println!("Size: {}", head.size);
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match head.htype {
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CA_FORMAT_FILENAME => {
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let name = self.read_filename(head.size)?;
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//let hash = compute_goodbye_hash(&rest[..rest.len()-1]);
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println!("Name: {:?}", name);
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let head: CaFormatHeader = self.read_item()?;
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check_ca_header::<CaFormatEntry>(&head, CA_FORMAT_ENTRY)?;
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let entry: CaFormatEntry = self.read_item()?;
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println!("Mode: {:08x} {:08x}", entry.mode, (entry.mode as u32) & libc::S_IFDIR);
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if ((entry.mode as u32) & libc::S_IFMT) == libc::S_IFDIR {
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nesting += 1;
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dirpath.push(&name);
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println!("Path: {:?}", dirpath);
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} else {
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dirpath.push(&name);
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println!("Path: {:?}", dirpath);
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dirpath.pop();
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}
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}
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CA_FORMAT_GOODBYE => {
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self.skip_bytes((head.size - HEADER_SIZE) as usize)?;
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nesting -= 1;
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println!("Goodbye: {:?}", dirpath);
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dirpath.pop();
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if nesting == 0 {
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// fixme: check eof??
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break;
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}
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}
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CA_FORMAT_SYMLINK => {
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let target = self.read_symlink(head.size)?;
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println!("Symlink: {:?}", target);
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}
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CA_FORMAT_DEVICE => {
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let device: CaFormatDevice = self.read_item()?;
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println!("Device: {}, {}", device.major, device.minor);
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}
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CA_FORMAT_PAYLOAD => {
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let payload_size = (head.size - HEADER_SIZE) as usize;
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println!("Payload: {}", payload_size);
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self.skip_bytes(payload_size)?;
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}
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_ => {
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panic!("unknown header type");
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}
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}
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}
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Ok(())
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}
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}
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fn file_openat(parent: RawFd, filename: &OsStr, flags: OFlag, mode: Mode) -> Result<std::fs::File, Error> {
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let fd = filename.with_nix_path(|cstr| {
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nix::fcntl::openat(parent, cstr.as_ref(), flags, mode)
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})??;
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let file = unsafe { std::fs::File::from_raw_fd(fd) };
|
|
|
|
Ok(file)
|
|
}
|
|
|
|
fn dir_mkdirat(parent: RawFd, filename: &OsStr, create_new: bool) -> Result<nix::dir::Dir, nix::Error> {
|
|
|
|
// call mkdirat first
|
|
let res = filename.with_nix_path(|cstr| unsafe {
|
|
libc::mkdirat(parent, cstr.as_ptr(), libc::S_IRWXU)
|
|
})?;
|
|
|
|
match Errno::result(res) {
|
|
Ok(_) => {},
|
|
Err(err) => {
|
|
if err == nix::Error::Sys(nix::errno::Errno::EEXIST) {
|
|
if create_new { return Err(err); }
|
|
} else {
|
|
return Err(err);
|
|
}
|
|
}
|
|
}
|
|
|
|
let dir = nix::dir::Dir::openat(parent, filename, OFlag::O_DIRECTORY, Mode::empty())?;
|
|
|
|
Ok(dir)
|
|
}
|
|
|
|
fn symlinkat(target: &Path, parent: RawFd, linkname: &OsStr) -> Result<(), Error> {
|
|
|
|
target.with_nix_path(|target| {
|
|
linkname.with_nix_path(|linkname| {
|
|
let res = unsafe { libc::symlinkat(target.as_ptr(), parent, linkname.as_ptr()) };
|
|
Errno::result(res)?;
|
|
Ok(())
|
|
})?
|
|
})?
|
|
}
|
|
|
|
fn nsec_to_update_timespec(mtime_nsec: u64) -> [libc::timespec; 2] {
|
|
|
|
// restore mtime
|
|
const UTIME_OMIT: i64 = ((1 << 30) - 2);
|
|
const NANOS_PER_SEC: i64 = 1_000_000_000;
|
|
|
|
let sec = (mtime_nsec as i64) / NANOS_PER_SEC;
|
|
let nsec = (mtime_nsec as i64) % NANOS_PER_SEC;
|
|
|
|
let times: [libc::timespec; 2] = [
|
|
libc::timespec { tv_sec: 0, tv_nsec: UTIME_OMIT },
|
|
libc::timespec { tv_sec: sec, tv_nsec: nsec },
|
|
];
|
|
|
|
times
|
|
}
|