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dirstate-tree: Add tree traversal/iteration Like Python’s, Rust’s iterators are "external" in that they are driven by a caller who calls a `next` method. This is as opposed to "internal" iterators who drive themselves and call a callback for each item. Writing an internal iterator traversing a tree is easy with recursion, but internal iterators cannot rely on the call stack in that way, they must save in an explicit object all state that they need to be preserved across two `next` calls. This algorithm uses a `Vec` as a stack that contains what would be local variables on the call stack if we could use recursion. Differential Revision: https://phab.mercurial-scm.org/D10370

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path_auditor.rs
233 lines | 8.0 KiB | application/rls-services+xml | RustLexer
// path_auditor.rs
//
// Copyright 2020
// Raphaël Gomès <rgomes@octobus.net>,
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.
use crate::utils::{
files::lower_clean,
find_slice_in_slice,
hg_path::{hg_path_to_path_buf, HgPath, HgPathBuf, HgPathError},
};
use std::collections::HashSet;
use std::path::{Path, PathBuf};
use std::sync::{Mutex, RwLock};
/// Ensures that a path is valid for use in the repository i.e. does not use
/// any banned components, does not traverse a symlink, etc.
#[derive(Debug, Default)]
pub struct PathAuditor {
audited: Mutex<HashSet<HgPathBuf>>,
audited_dirs: RwLock<HashSet<HgPathBuf>>,
root: PathBuf,
}
impl PathAuditor {
pub fn new(root: impl AsRef<Path>) -> Self {
Self {
root: root.as_ref().to_owned(),
..Default::default()
}
}
pub fn audit_path(
&self,
path: impl AsRef<HgPath>,
) -> Result<(), HgPathError> {
// TODO windows "localpath" normalization
let path = path.as_ref();
if path.is_empty() {
return Ok(());
}
// TODO case normalization
if self.audited.lock().unwrap().contains(path) {
return Ok(());
}
// AIX ignores "/" at end of path, others raise EISDIR.
let last_byte = path.as_bytes()[path.len() - 1];
if last_byte == b'/' || last_byte == b'\\' {
return Err(HgPathError::EndsWithSlash(path.to_owned()));
}
let parts: Vec<_> = path
.as_bytes()
.split(|b| std::path::is_separator(*b as char))
.collect();
let first_component = lower_clean(parts[0]);
let first_component = first_component.as_slice();
if !path.split_drive().0.is_empty()
|| (first_component == b".hg"
|| first_component == b".hg."
|| first_component == b"")
|| parts.iter().any(|c| c == b"..")
{
return Err(HgPathError::InsideDotHg(path.to_owned()));
}
// Windows shortname aliases
for part in parts.iter() {
if part.contains(&b'~') {
let mut split = part.splitn(2, |b| *b == b'~');
let first =
split.next().unwrap().to_owned().to_ascii_uppercase();
let last = split.next().unwrap();
if last.iter().all(u8::is_ascii_digit)
&& (first == b"HG" || first == b"HG8B6C")
{
return Err(HgPathError::ContainsIllegalComponent(
path.to_owned(),
));
}
}
}
let lower_path = lower_clean(path.as_bytes());
if find_slice_in_slice(&lower_path, b".hg").is_some() {
let lower_parts: Vec<_> = path
.as_bytes()
.split(|b| std::path::is_separator(*b as char))
.collect();
for pattern in [b".hg".to_vec(), b".hg.".to_vec()].iter() {
if let Some(pos) = lower_parts[1..]
.iter()
.position(|part| part == &pattern.as_slice())
{
let base = lower_parts[..=pos]
.iter()
.fold(HgPathBuf::new(), |acc, p| {
acc.join(HgPath::new(p))
});
return Err(HgPathError::IsInsideNestedRepo {
path: path.to_owned(),
nested_repo: base,
});
}
}
}
let parts = &parts[..parts.len().saturating_sub(1)];
// We don't want to add "foo/bar/baz" to `audited_dirs` before checking
// if there's a "foo/.hg" directory. This also means we won't
// accidentally traverse a symlink into some other filesystem (which
// is potentially expensive to access).
for index in 0..parts.len() {
let prefix = &parts[..=index].join(&b'/');
let prefix = HgPath::new(prefix);
if self.audited_dirs.read().unwrap().contains(prefix) {
continue;
}
self.check_filesystem(&prefix, &path)?;
self.audited_dirs.write().unwrap().insert(prefix.to_owned());
}
self.audited.lock().unwrap().insert(path.to_owned());
Ok(())
}
pub fn check_filesystem(
&self,
prefix: impl AsRef<HgPath>,
path: impl AsRef<HgPath>,
) -> Result<(), HgPathError> {
let prefix = prefix.as_ref();
let path = path.as_ref();
let current_path = self.root.join(
hg_path_to_path_buf(prefix)
.map_err(|_| HgPathError::NotFsCompliant(path.to_owned()))?,
);
match std::fs::symlink_metadata(&current_path) {
Err(e) => {
// EINVAL can be raised as invalid path syntax under win32.
if e.kind() != std::io::ErrorKind::NotFound
&& e.kind() != std::io::ErrorKind::InvalidInput
&& e.raw_os_error() != Some(20)
{
// Rust does not yet have an `ErrorKind` for
// `NotADirectory` (errno 20)
// It happens if the dirstate contains `foo/bar` and
// foo is not a directory
return Err(HgPathError::NotFsCompliant(path.to_owned()));
}
}
Ok(meta) => {
if meta.file_type().is_symlink() {
return Err(HgPathError::TraversesSymbolicLink {
path: path.to_owned(),
symlink: prefix.to_owned(),
});
}
if meta.file_type().is_dir()
&& current_path.join(".hg").is_dir()
{
return Err(HgPathError::IsInsideNestedRepo {
path: path.to_owned(),
nested_repo: prefix.to_owned(),
});
}
}
};
Ok(())
}
pub fn check(&self, path: impl AsRef<HgPath>) -> bool {
self.audit_path(path).is_ok()
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::utils::files::get_path_from_bytes;
use crate::utils::hg_path::path_to_hg_path_buf;
#[test]
fn test_path_auditor() {
let auditor = PathAuditor::new(get_path_from_bytes(b"/tmp"));
let path = HgPath::new(b".hg/00changelog.i");
assert_eq!(
auditor.audit_path(path),
Err(HgPathError::InsideDotHg(path.to_owned()))
);
let path = HgPath::new(b"this/is/nested/.hg/thing.txt");
assert_eq!(
auditor.audit_path(path),
Err(HgPathError::IsInsideNestedRepo {
path: path.to_owned(),
nested_repo: HgPathBuf::from_bytes(b"this/is/nested")
})
);
use std::fs::{create_dir, File};
use tempfile::tempdir;
let base_dir = tempdir().unwrap();
let base_dir_path = base_dir.path();
let skip = base_dir_path.components().count() - 1;
let a = base_dir_path.join("a");
let b = base_dir_path.join("b");
create_dir(&a).unwrap();
let in_a_path = a.join("in_a");
File::create(in_a_path).unwrap();
// TODO make portable
std::os::unix::fs::symlink(&a, &b).unwrap();
let buf = b.join("in_a").components().skip(skip).collect::<PathBuf>();
eprintln!("buf: {}", buf.display());
let path = path_to_hg_path_buf(buf).unwrap();
assert_eq!(
auditor.audit_path(&path),
Err(HgPathError::TraversesSymbolicLink {
path: path,
symlink: path_to_hg_path_buf(
b.components().skip(2).collect::<PathBuf>()
)
.unwrap()
})
);
}
}