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pxar: implement hardlinks

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So we are no longer compatible with catar ...
This commit is contained in:
Dietmar Maurer
2019-03-16 11:02:12 +01:00
parent c238e4d4b3
commit af572aaa4c
4 changed files with 125 additions and 41 deletions
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8
src/pxar.rs
View File

@ -38,6 +38,14 @@
//! * ...
//! * GOODBYE -- lookup table at the end of a list of directory entries
///! The original format has no way to deal with hardlinks, so we
///! extended the format by a special HARDLINK tag, which can replace
///! an ENTRY tag. The HARDLINK tag contains an 64bit offset which
///! points to the linked ENTRY inside the archive, followed by the
///! full path name of that ENTRY. HARDLINKs may not have further data
///! (user, group, acl, ...) because this is already defined by the
///! linked ENTRY.
mod binary_search_tree;
pub use binary_search_tree::*;

38
src/pxar/encoder.rs
View File

@ -44,7 +44,7 @@ pub struct Encoder<'a, W: Write> {
all_file_systems: bool,
root_st_dev: u64,
verbose: bool,
hardlinks: HashMap<HardLinkInfo, PathBuf>,
hardlinks: HashMap<HardLinkInfo, (PathBuf, u64)>,
}
impl <'a, W: Write> Encoder<'a, W> {
@ -355,15 +355,26 @@ impl <'a, W: Write> Encoder<'a, W> {
} else if ifmt == libc::S_IFREG {
let mut hardlink_target = None;
if stat.st_nlink > 1 {
let link_info = HardLinkInfo { st_dev: stat.st_dev, st_ino: stat.st_ino };
if let Some(target) = self.hardlinks.get(&link_info) {
// fixme: store hardlink info somwhow?
eprintln!("FOUND HARDLINK {:?}", target);
hardlink_target = self.hardlinks.get(&link_info).map(|(v, offset)| {
let mut target = v.clone().into_os_string();
target.push("\0"); // add Nul byte
(target, (start_pos as u64) - offset)
});
if hardlink_target == None {
self.hardlinks.insert(link_info, (self.relative_path.clone(), start_pos as u64));
}
}
if let Some((target, offset)) = hardlink_target {
self.write_filename(&filename)?;
self.encode_hardlink(target.as_bytes(), offset)?;
} else {
self.hardlinks.insert(link_info, self.relative_path.clone());
}
}
let filefd = match nix::fcntl::openat(rawfd, filename.as_ref(), OFlag::O_NOFOLLOW, Mode::empty()) {
Ok(filefd) => filefd,
@ -384,6 +395,7 @@ impl <'a, W: Write> Encoder<'a, W> {
let res = self.encode_file(filefd, &stat, child_magic);
let _ = nix::unistd::close(filefd); // ignore close errors
res?;
}
} else if ifmt == libc::S_IFLNK {
let mut buffer = [0u8; libc::PATH_MAX as usize];
@ -540,6 +552,18 @@ impl <'a, W: Write> Encoder<'a, W> {
Ok(())
}
fn encode_hardlink(&mut self, target: &[u8], offset: u64) -> Result<(), Error> {
//println!("encode_hardlink: {:?} -> {:?}", self.full_path(), target);
// Note: HARDLINK replaces an ENTRY.
self.write_header(PXAR_FORMAT_HARDLINK, (target.len() as u64) + 8)?;
self.write_item(offset)?;
self.write(target)?;
Ok(())
}
// the report_XXX method may raise and error - depending on encoder configuration
fn report_vanished_file(&self, path: &Path) -> Result<(), Error> {

3
src/pxar/format_definition.rs
View File

@ -15,6 +15,9 @@ pub const CA_FORMAT_FILENAME: u64 = 0x6dbb6ebcb3161f0b;
pub const CA_FORMAT_SYMLINK: u64 = 0x664a6fb6830e0d6c;
pub const CA_FORMAT_DEVICE: u64 = 0xac3dace369dfe643;
// compute_goodbye_hash(b"__PROXMOX_FORMAT_HARDLINK__");
pub const PXAR_FORMAT_HARDLINK: u64 = 0x2c5e06f634f65b86;
pub const CA_FORMAT_PAYLOAD: u64 = 0x8b9e1d93d6dcffc9;
pub const CA_FORMAT_GOODBYE: u64 = 0xdfd35c5e8327c403;

87
src/pxar/sequential_decoder.rs
View File

@ -54,14 +54,14 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
Ok(result.from_le())
}
fn read_symlink(&mut self, size: u64) -> Result<PathBuf, Error> {
fn read_link(&mut self, size: u64) -> Result<PathBuf, Error> {
if size < (HEADER_SIZE + 2) {
bail!("dectected short symlink target.");
bail!("dectected short link target.");
}
let target_len = size - HEADER_SIZE;
if target_len > (libc::PATH_MAX as u64) {
bail!("symlink target too long ({}).", target_len);
bail!("link target too long ({}).", target_len);
}
let mut buffer = vec![0u8; target_len as usize];
@ -69,12 +69,31 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
let last_byte = buffer.pop().unwrap();
if last_byte != 0u8 {
bail!("symlink target not nul terminated.");
bail!("link target not nul terminated.");
}
Ok(PathBuf::from(std::ffi::OsString::from_vec(buffer)))
}
fn read_hardlink(&mut self, size: u64) -> Result<(PathBuf, u64), Error> {
if size < (HEADER_SIZE + 8 + 2) {
bail!("dectected short hardlink header.");
}
let offset: u64 = self.read_item()?;
let target = self.read_link(size - 8)?;
for c in target.components() {
match c {
std::path::Component::Normal(_) => { /* OK */ },
_ => {
bail!("hardlink target contains invalid component {:?}", c);
}
}
}
Ok((target, offset))
}
pub (crate) fn read_filename(&mut self, size: u64) -> Result<OsString, Error> {
if size < (HEADER_SIZE + 2) {
bail!("dectected short filename");
@ -250,13 +269,15 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
Err(err) => bail!("unable to open target directory {:?} - {}", path, err),
};
self.restore_sequential(&mut path.to_owned(), &OsString::new(), &dir, callback)
let mut relative_path = PathBuf::new();
self.restore_sequential(path, &mut relative_path, &OsString::new(), &dir, callback)
}
fn restore_sequential<F>(
&mut self,
path: &mut PathBuf, // used for error reporting
filename: &OsStr, // repeats path last component
base_path: &Path,
relative_path: &mut PathBuf,
filename: &OsStr, // repeats path last relative_path component
parent: &nix::dir::Dir,
callback: &F,
) -> Result<(), Error>
@ -265,12 +286,23 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
let parent_fd = parent.as_raw_fd();
// read ENTRY first
let full_path = base_path.join(&relative_path);
(callback)(&full_path)?;
let head: CaFormatHeader = self.read_item()?;
if head.htype == PXAR_FORMAT_HARDLINK {
let (target, _offset) = self.read_hardlink(head.size)?;
let target_path = base_path.join(&target);
//println!("HARDLINK: {} {:?} -> {:?}", offset, full_path, target_path);
hardlink(&target_path, &full_path)?;
return Ok(());
}
check_ca_header::<CaFormatEntry>(&head, CA_FORMAT_ENTRY)?;
let entry: CaFormatEntry = self.read_item()?;
(callback)(path)?;
let mode = entry.mode as u32; //fixme: upper 32bits?
@ -283,7 +315,7 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
} else {
dir = match dir_mkdirat(parent_fd, filename, true) {
Ok(dir) => dir,
Err(err) => bail!("unable to open directory {:?} - {}", path, err),
Err(err) => bail!("unable to open directory {:?} - {}", full_path, err),
};
}
@ -291,10 +323,9 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
while head.htype == CA_FORMAT_FILENAME {
let name = self.read_filename(head.size)?;
path.push(&name);
//println!("NAME: {:?}", path);
self.restore_sequential(path, &name, &dir, callback)?;
path.pop();
relative_path.push(&name);
self.restore_sequential(base_path, relative_path, &name, &dir, callback)?;
relative_path.pop();
head = self.read_item()?;
}
@ -316,7 +347,7 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
}
if filename.is_empty() {
bail!("got empty file name at {:?}", path)
bail!("got empty file name at {:?}", full_path)
}
if ifmt == libc::S_IFLNK {
@ -326,10 +357,10 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
let head: CaFormatHeader = self.read_item()?;
match head.htype {
CA_FORMAT_SYMLINK => {
let target = self.read_symlink(head.size)?;
let target = self.read_link(head.size)?;
//println!("TARGET: {:?}", target);
if let Err(err) = symlinkat(&target, parent_fd, filename) {
bail!("create symlink {:?} failed - {}", path, err);
bail!("create symlink {:?} failed - {}", full_path, err);
}
}
_ => {
@ -395,7 +426,7 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
let mut file = match file_openat(parent_fd, filename, flags, open_mode) {
Ok(file) => file,
Err(err) => bail!("open file {:?} failed - {}", path, err),
Err(err) => bail!("open file {:?} failed - {}", full_path, err),
};
let head = self.restore_attributes(&entry)?;
@ -454,6 +485,14 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
println!("{:?}", path);
}
if head.htype == PXAR_FORMAT_HARDLINK {
let (target, offset) = self.read_hardlink(head.size)?;
if verbose {
println!("Hardlink: {} {:?}", offset, target);
}
return Ok(());
}
check_ca_header::<CaFormatEntry>(&head, CA_FORMAT_ENTRY)?;
let entry: CaFormatEntry = self.read_item()?;
@ -509,7 +548,7 @@ impl <'a, R: Read> SequentialDecoder<'a, R> {
match head.htype {
CA_FORMAT_SYMLINK => {
let target = self.read_symlink(head.size)?;
let target = self.read_link(head.size)?;
if verbose {
println!("Symlink: {:?}", target);
}
@ -622,6 +661,16 @@ fn dir_mkdirat(parent: RawFd, filename: &OsStr, create_new: bool) -> Result<nix:
Ok(dir)
}
fn hardlink(oldpath: &Path, newpath: &Path) -> Result<(), Error> {
oldpath.with_nix_path(|oldpath| {
newpath.with_nix_path(|newpath| {
let res = unsafe { libc::link(oldpath.as_ptr(), newpath.as_ptr()) };
Errno::result(res)?;
Ok(())
})?
})?
}
fn symlinkat(target: &Path, parent: RawFd, linkname: &OsStr) -> Result<(), Error> {
target.with_nix_path(|target| {