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//! Defines helpers and utilities for working with file system paths
use std::fmt;
use std::io;
use std::mem;
use std::ops::Deref;
use std::path::{Component, Path, PathBuf};
/// An error that can arise during physical path normalization.
#[derive(Debug, thiserror::Error)]
pub struct NormalizationError {
/// The error that occured.
#[source]
err: io::Error,
/// The path that caused the error.
path: PathBuf,
}
impl fmt::Display for NormalizationError {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(fmt, "{}: {}", self.err, self.path.display())
}
}
/// A `PathBuf` wrapper which ensures paths do not have `.` or `..` components.
#[derive(PartialEq, Eq, Clone, Debug, Default)]
pub struct NormalizedPath {
/// Inner path buffer which *always* remains normalized.
normalized_path: PathBuf,
}
pub(crate) fn has_dot_components(path: &Path) -> bool {
path.components().any(|c| match c {
Component::CurDir | Component::ParentDir => true,
Component::Prefix(_) | Component::RootDir | Component::Normal(_) => false,
})
}
impl NormalizedPath {
/// Creates a new, empty `NormalizedPath`.
pub fn new() -> Self {
Self {
normalized_path: PathBuf::new(),
}
}
/// Creates a new `NormalizedPath` instance with the provided buffer.
///
/// If `buf` is non-empty, it will be logically normalized as needed.
/// See the documentation for `join_normalized_logial` for more
/// information on how the normalization is performed.
pub fn new_normalized_logical(buf: PathBuf) -> Self {
if has_dot_components(&buf) {
let mut normalized = Self::new();
normalized.perform_join_normalized_logical(&buf);
normalized
} else {
Self {
normalized_path: buf,
}
}
}
/// Creates a new `NormalizedPath` instance with the provided buffer.
///
/// If `buf` is non-empty, it will be physically normalized as needed.
/// See the documentation for `join_normalized_physical` for more
/// information on how the normalization is performed.
pub fn new_normalized_physical(buf: PathBuf) -> Result<Self, NormalizationError> {
if has_dot_components(&buf) {
let mut normalized_path = Self::new();
normalized_path.perform_join_normalized_physical_for_dot_components(&buf)?;
Ok(normalized_path)
} else {
// Ensure we've resolved all possible symlinks
let normalized_path = buf
.canonicalize()
.map_err(|e| NormalizationError { err: e, path: buf })?;
Ok(Self { normalized_path })
}
}
/// Joins a path to the buffer, normalizing away any `.` or `..` components,
/// without following any symbolic links.
///
/// For example, joining `../some/path` to `/root/dir` will yield
/// `/root/some/path`.
///
/// The normal behaviors of joining `Path`s will take effect (e.g. joining
/// with an absolute path will replace the previous contents).
pub fn join_normalized_logial<P: AsRef<Path>>(&mut self, path: P) {
self.join_normalized_logial_(path.as_ref())
}
fn join_normalized_logial_(&mut self, path: &Path) {
// If we have no relative components to resolve then we can avoid
// multiple reallocations by pushing the entiere path at once.
if !has_dot_components(path) {
self.normalized_path.push(path);
return;
}
self.perform_join_normalized_logical(path);
}
fn perform_join_normalized_logical(&mut self, path: &Path) {
for component in path.components() {
match component {
c @ Component::Prefix(_) | c @ Component::RootDir | c @ Component::Normal(_) => {
self.normalized_path.push(c.as_os_str())
}
Component::CurDir => {}
Component::ParentDir => {
self.normalized_path.pop();
}
}
}
}
/// Joins a path to the buffer, normalizing away any `.` or `..` components
/// after following any symbolic links.
///
/// For example, joining `../some/path` to `/root/dir` (where `/root/dir`
/// is a symlink to `/root/another/place`) will yield `/root/another/some/path`.
///
/// The normal behaviors of joining `Path`s will take effect (e.g. joining
/// with an absolute path will replace the previous contents).
///
/// # Errors
///
/// If an error occurs while resolving symlinks, the current path buffer
/// will be reset to its previous state (as if the call never happened)
/// before the error is propagated to the caller.
pub fn join_normalized_physical<P: AsRef<Path>>(
&mut self,
path: P,
) -> Result<(), NormalizationError> {
self.join_normalized_physical_(path.as_ref())
}
fn join_normalized_physical_(&mut self, path: &Path) -> Result<(), NormalizationError> {
if has_dot_components(path) {
self.perform_join_normalized_physical_for_dot_components(path)
} else {
// If we have no relative components to resolve then we can avoid
// multiple reallocations by pushing the entiere path at once.
self.normalized_path.push(path);
self.normalized_path =
self.normalized_path
.canonicalize()
.map_err(|e| NormalizationError {
err: e,
path: self.normalized_path.clone(),
})?;
Ok(())
}
}
fn perform_join_normalized_physical_for_dot_components(
&mut self,
path: &Path,
) -> Result<(), NormalizationError> {
let orig_path = self.normalized_path.clone();
self.perform_join_normalized_physical(path)
.map_err(|e| NormalizationError {
err: e,
path: mem::replace(&mut self.normalized_path, orig_path),
})
}
fn perform_join_normalized_physical(&mut self, path: &Path) -> io::Result<()> {
for component in path.components() {
match component {
c @ Component::Prefix(_) | c @ Component::RootDir | c @ Component::Normal(_) => {
self.normalized_path.push(c.as_os_str())
}
Component::CurDir => {}
Component::ParentDir => {
self.normalized_path = self.normalized_path.canonicalize()?;
self.normalized_path.pop();
}
}
}
// Perform one last resolution of all potential symlinks
self.normalized_path = self.normalized_path.canonicalize()?;
Ok(())
}
/// Unwraps the inner `PathBuf`.
pub fn into_inner(self) -> PathBuf {
self.normalized_path
}
}
impl Deref for NormalizedPath {
type Target = PathBuf;
fn deref(&self) -> &PathBuf {
&self.normalized_path
}
}