Revision control
Copy as Markdown
Other Tools
//! List directory contents
use crate::errno::Errno;
use crate::fcntl::{self, OFlag};
use crate::sys;
use crate::{Error, NixPath, Result};
use cfg_if::cfg_if;
use std::ffi;
use std::os::unix::io::{AsRawFd, IntoRawFd, RawFd};
use std::ptr;
#[cfg(target_os = "linux")]
use libc::{dirent64 as dirent, readdir64_r as readdir_r};
#[cfg(not(target_os = "linux"))]
use libc::{dirent, readdir_r};
/// An open directory.
///
/// This is a lower-level interface than `std::fs::ReadDir`. Notable differences:
/// * can be opened from a file descriptor (as returned by `openat`, perhaps before knowing
/// if the path represents a file or directory).
/// * implements `AsRawFd`, so it can be passed to `fstat`, `openat`, etc.
/// The file descriptor continues to be owned by the `Dir`, so callers must not keep a `RawFd`
/// after the `Dir` is dropped.
/// * can be iterated through multiple times without closing and reopening the file
/// descriptor. Each iteration rewinds when finished.
/// * returns entries for `.` (current directory) and `..` (parent directory).
/// * returns entries' names as a `CStr` (no allocation or conversion beyond whatever libc
/// does).
#[derive(Debug, Eq, Hash, PartialEq)]
pub struct Dir(ptr::NonNull<libc::DIR>);
impl Dir {
/// Opens the given path as with `fcntl::open`.
pub fn open<P: ?Sized + NixPath>(
path: &P,
oflag: OFlag,
mode: sys::stat::Mode,
) -> Result<Self> {
let fd = fcntl::open(path, oflag, mode)?;
Dir::from_fd(fd)
}
/// Opens the given path as with `fcntl::openat`.
pub fn openat<P: ?Sized + NixPath>(
dirfd: Option<RawFd>,
path: &P,
oflag: OFlag,
mode: sys::stat::Mode,
) -> Result<Self> {
let fd = fcntl::openat(dirfd, path, oflag, mode)?;
Dir::from_fd(fd)
}
/// Converts from a descriptor-based object, closing the descriptor on success or failure.
#[inline]
pub fn from<F: IntoRawFd>(fd: F) -> Result<Self> {
Dir::from_fd(fd.into_raw_fd())
}
/// Converts from a file descriptor, closing it on failure.
#[doc(alias("fdopendir"))]
pub fn from_fd(fd: RawFd) -> Result<Self> {
let d = ptr::NonNull::new(unsafe { libc::fdopendir(fd) }).ok_or_else(
|| {
let e = Error::last();
unsafe { libc::close(fd) };
e
},
)?;
Ok(Dir(d))
}
/// Returns an iterator of `Result<Entry>` which rewinds when finished.
pub fn iter(&mut self) -> Iter {
Iter(self)
}
}
// `Dir` is not `Sync`. With the current implementation, it could be, but according to
// future versions of POSIX are likely to obsolete `readdir_r` and specify that it's unsafe to
// call `readdir` simultaneously from multiple threads.
//
// `Dir` is safe to pass from one thread to another, as it's not reference-counted.
unsafe impl Send for Dir {}
impl AsRawFd for Dir {
fn as_raw_fd(&self) -> RawFd {
unsafe { libc::dirfd(self.0.as_ptr()) }
}
}
impl Drop for Dir {
fn drop(&mut self) {
let e = Errno::result(unsafe { libc::closedir(self.0.as_ptr()) });
if !std::thread::panicking() && e == Err(Errno::EBADF) {
panic!("Closing an invalid file descriptor!");
};
}
}
// The pass by mut is technically needless only because the inner NonNull is
// Copy. But philosophically we're mutating the Dir, so we pass by mut.
#[allow(clippy::needless_pass_by_ref_mut)]
fn next(dir: &mut Dir) -> Option<Result<Entry>> {
unsafe {
// Note: POSIX specifies that portable applications should dynamically allocate a
// buffer with room for a `d_name` field of size `pathconf(..., _PC_NAME_MAX)` plus 1
// for the NUL byte. It doesn't look like the std library does this; it just uses
// fixed-sized buffers (and libc's dirent seems to be sized so this is appropriate).
// Probably fine here too then.
let mut ent = std::mem::MaybeUninit::<dirent>::uninit();
let mut result = ptr::null_mut();
if let Err(e) = Errno::result(readdir_r(
dir.0.as_ptr(),
ent.as_mut_ptr(),
&mut result,
)) {
return Some(Err(e));
}
if result.is_null() {
return None;
}
assert_eq!(result, ent.as_mut_ptr());
Some(Ok(Entry(ent.assume_init())))
}
}
/// Return type of [`Dir::iter`].
#[derive(Debug, Eq, Hash, PartialEq)]
pub struct Iter<'d>(&'d mut Dir);
impl<'d> Iterator for Iter<'d> {
type Item = Result<Entry>;
fn next(&mut self) -> Option<Self::Item> {
next(self.0)
}
}
impl<'d> Drop for Iter<'d> {
fn drop(&mut self) {
unsafe { libc::rewinddir((self.0).0.as_ptr()) }
}
}
/// The return type of [Dir::into_iter]
#[derive(Debug, Eq, Hash, PartialEq)]
pub struct OwningIter(Dir);
impl Iterator for OwningIter {
type Item = Result<Entry>;
fn next(&mut self) -> Option<Self::Item> {
next(&mut self.0)
}
}
/// The file descriptor continues to be owned by the `OwningIter`,
/// so callers must not keep a `RawFd` after the `OwningIter` is dropped.
impl AsRawFd for OwningIter {
fn as_raw_fd(&self) -> RawFd {
self.0.as_raw_fd()
}
}
impl IntoIterator for Dir {
type Item = Result<Entry>;
type IntoIter = OwningIter;
/// Creates a owning iterator, that is, one that takes ownership of the
/// `Dir`. The `Dir` cannot be used after calling this. This can be useful
/// when you have a function that both creates a `Dir` instance and returns
/// an `Iterator`.
///
/// Example:
///
/// ```
/// use nix::{dir::Dir, fcntl::OFlag, sys::stat::Mode};
/// use std::{iter::Iterator, string::String};
///
/// fn ls_upper(dirname: &str) -> impl Iterator<Item=String> {
/// let d = Dir::open(dirname, OFlag::O_DIRECTORY, Mode::S_IXUSR).unwrap();
/// d.into_iter().map(|x| x.unwrap().file_name().as_ref().to_string_lossy().to_ascii_uppercase())
/// }
/// ```
fn into_iter(self) -> Self::IntoIter {
OwningIter(self)
}
}
/// A directory entry, similar to `std::fs::DirEntry`.
///
/// Note that unlike the std version, this may represent the `.` or `..` entries.
#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq)]
#[repr(transparent)]
pub struct Entry(dirent);
/// Type of file referenced by a directory entry
#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq)]
pub enum Type {
/// FIFO (Named pipe)
Fifo,
/// Character device
CharacterDevice,
/// Directory
Directory,
/// Block device
BlockDevice,
/// Regular file
File,
/// Symbolic link
Symlink,
/// Unix-domain socket
Socket,
}
impl Entry {
/// Returns the inode number (`d_ino`) of the underlying `dirent`.
#[allow(clippy::useless_conversion)] // Not useless on all OSes
// The cast is not unnecessary on all platforms.
#[allow(clippy::unnecessary_cast)]
pub fn ino(&self) -> u64 {
cfg_if! {
if #[cfg(any(target_os = "aix",
target_os = "emscripten",
target_os = "fuchsia",
target_os = "haiku",
target_os = "hurd",
solarish,
linux_android,
apple_targets))] {
self.0.d_ino as u64
} else {
u64::from(self.0.d_fileno)
}
}
}
/// Returns the bare file name of this directory entry without any other leading path component.
pub fn file_name(&self) -> &ffi::CStr {
unsafe { ffi::CStr::from_ptr(self.0.d_name.as_ptr()) }
}
/// Returns the type of this directory entry, if known.
///
/// See platform `readdir(3)` or `dirent(5)` manpage for when the file type is known;
/// notably, some Linux filesystems don't implement this. The caller should use `stat` or
/// `fstat` if this returns `None`.
pub fn file_type(&self) -> Option<Type> {
#[cfg(not(any(solarish, target_os = "aix", target_os = "haiku")))]
match self.0.d_type {
libc::DT_FIFO => Some(Type::Fifo),
libc::DT_CHR => Some(Type::CharacterDevice),
libc::DT_DIR => Some(Type::Directory),
libc::DT_BLK => Some(Type::BlockDevice),
libc::DT_REG => Some(Type::File),
libc::DT_LNK => Some(Type::Symlink),
libc::DT_SOCK => Some(Type::Socket),
/* libc::DT_UNKNOWN | */ _ => None,
}
// illumos, Solaris, and Haiku systems do not have the d_type member at all:
#[cfg(any(solarish, target_os = "aix", target_os = "haiku"))]
None
}
}