1 //! Filesystem manipulation operations.
3 //! This module contains basic methods to manipulate the contents of the local
4 //! filesystem. All methods in this module represent cross-platform filesystem
5 //! operations. Extra platform-specific functionality can be found in the
6 //! extension traits of `std::os::$platform`.
8 #![stable(feature = "rust1", since = "1.0.0")]
9 #![deny(unsafe_op_in_unsafe_fn)]
11 #[cfg(all(test, not(any(target_os = "emscripten", target_env = "sgx"))))]
14 use crate::ffi::OsString;
16 use crate::io::{self, IoSlice, IoSliceMut, Read, ReadBuf, Seek, SeekFrom, Write};
17 use crate::path::{Path, PathBuf};
18 use crate::sys::fs as fs_imp;
19 use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
20 use crate::time::SystemTime;
22 /// A reference to an open file on the filesystem.
24 /// An instance of a `File` can be read and/or written depending on what options
25 /// it was opened with. Files also implement [`Seek`] to alter the logical cursor
26 /// that the file contains internally.
28 /// Files are automatically closed when they go out of scope. Errors detected
29 /// on closing are ignored by the implementation of `Drop`. Use the method
30 /// [`sync_all`] if these errors must be manually handled.
34 /// Creates a new file and write bytes to it (you can also use [`write()`]):
37 /// use std::fs::File;
38 /// use std::io::prelude::*;
40 /// fn main() -> std::io::Result<()> {
41 /// let mut file = File::create("foo.txt")?;
42 /// file.write_all(b"Hello, world!")?;
47 /// Read the contents of a file into a [`String`] (you can also use [`read`]):
50 /// use std::fs::File;
51 /// use std::io::prelude::*;
53 /// fn main() -> std::io::Result<()> {
54 /// let mut file = File::open("foo.txt")?;
55 /// let mut contents = String::new();
56 /// file.read_to_string(&mut contents)?;
57 /// assert_eq!(contents, "Hello, world!");
62 /// It can be more efficient to read the contents of a file with a buffered
63 /// [`Read`]er. This can be accomplished with [`BufReader<R>`]:
66 /// use std::fs::File;
67 /// use std::io::BufReader;
68 /// use std::io::prelude::*;
70 /// fn main() -> std::io::Result<()> {
71 /// let file = File::open("foo.txt")?;
72 /// let mut buf_reader = BufReader::new(file);
73 /// let mut contents = String::new();
74 /// buf_reader.read_to_string(&mut contents)?;
75 /// assert_eq!(contents, "Hello, world!");
80 /// Note that, although read and write methods require a `&mut File`, because
81 /// of the interfaces for [`Read`] and [`Write`], the holder of a `&File` can
82 /// still modify the file, either through methods that take `&File` or by
83 /// retrieving the underlying OS object and modifying the file that way.
84 /// Additionally, many operating systems allow concurrent modification of files
85 /// by different processes. Avoid assuming that holding a `&File` means that the
86 /// file will not change.
88 /// # Platform-specific behavior
90 /// On Windows, the implementation of [`Read`] and [`Write`] traits for `File`
91 /// perform synchronous I/O operations. Therefore the underlying file must not
92 /// have been opened for asynchronous I/O (e.g. by using `FILE_FLAG_OVERLAPPED`).
94 /// [`BufReader<R>`]: io::BufReader
95 /// [`sync_all`]: File::sync_all
96 #[stable(feature = "rust1", since = "1.0.0")]
97 #[cfg_attr(not(test), rustc_diagnostic_item = "File")]
102 /// Metadata information about a file.
104 /// This structure is returned from the [`metadata`] or
105 /// [`symlink_metadata`] function or method and represents known
106 /// metadata about a file such as its permissions, size, modification
108 #[stable(feature = "rust1", since = "1.0.0")]
110 pub struct Metadata(fs_imp::FileAttr);
112 /// Iterator over the entries in a directory.
114 /// This iterator is returned from the [`read_dir`] function of this module and
115 /// will yield instances of <code>[io::Result]<[DirEntry]></code>. Through a [`DirEntry`]
116 /// information like the entry's path and possibly other metadata can be
119 /// The order in which this iterator returns entries is platform and filesystem
124 /// This [`io::Result`] will be an [`Err`] if there's some sort of intermittent
125 /// IO error during iteration.
126 #[stable(feature = "rust1", since = "1.0.0")]
128 pub struct ReadDir(fs_imp::ReadDir);
130 /// Entries returned by the [`ReadDir`] iterator.
132 /// An instance of `DirEntry` represents an entry inside of a directory on the
133 /// filesystem. Each entry can be inspected via methods to learn about the full
134 /// path or possibly other metadata through per-platform extension traits.
136 /// # Platform-specific behavior
138 /// On Unix, the `DirEntry` struct contains an internal reference to the open
139 /// directory. Holding `DirEntry` objects will consume a file handle even
140 /// after the `ReadDir` iterator is dropped.
142 /// Note that this [may change in the future][changes].
144 /// [changes]: io#platform-specific-behavior
145 #[stable(feature = "rust1", since = "1.0.0")]
146 pub struct DirEntry(fs_imp::DirEntry);
148 /// Options and flags which can be used to configure how a file is opened.
150 /// This builder exposes the ability to configure how a [`File`] is opened and
151 /// what operations are permitted on the open file. The [`File::open`] and
152 /// [`File::create`] methods are aliases for commonly used options using this
155 /// Generally speaking, when using `OpenOptions`, you'll first call
156 /// [`OpenOptions::new`], then chain calls to methods to set each option, then
157 /// call [`OpenOptions::open`], passing the path of the file you're trying to
158 /// open. This will give you a [`io::Result`] with a [`File`] inside that you
159 /// can further operate on.
163 /// Opening a file to read:
166 /// use std::fs::OpenOptions;
168 /// let file = OpenOptions::new().read(true).open("foo.txt");
171 /// Opening a file for both reading and writing, as well as creating it if it
175 /// use std::fs::OpenOptions;
177 /// let file = OpenOptions::new()
181 /// .open("foo.txt");
183 #[derive(Clone, Debug)]
184 #[stable(feature = "rust1", since = "1.0.0")]
185 pub struct OpenOptions(fs_imp::OpenOptions);
187 /// Representation of the various timestamps on a file.
188 #[derive(Copy, Clone, Debug, Default)]
189 #[unstable(feature = "file_set_times", issue = "98245")]
190 pub struct FileTimes(fs_imp::FileTimes);
192 /// Representation of the various permissions on a file.
194 /// This module only currently provides one bit of information,
195 /// [`Permissions::readonly`], which is exposed on all currently supported
196 /// platforms. Unix-specific functionality, such as mode bits, is available
197 /// through the [`PermissionsExt`] trait.
199 /// [`PermissionsExt`]: crate::os::unix::fs::PermissionsExt
200 #[derive(Clone, PartialEq, Eq, Debug)]
201 #[stable(feature = "rust1", since = "1.0.0")]
202 pub struct Permissions(fs_imp::FilePermissions);
204 /// A structure representing a type of file with accessors for each file type.
205 /// It is returned by [`Metadata::file_type`] method.
206 #[stable(feature = "file_type", since = "1.1.0")]
207 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
208 #[cfg_attr(not(test), rustc_diagnostic_item = "FileType")]
209 pub struct FileType(fs_imp::FileType);
211 /// A builder used to create directories in various manners.
213 /// This builder also supports platform-specific options.
214 #[stable(feature = "dir_builder", since = "1.6.0")]
215 #[cfg_attr(not(test), rustc_diagnostic_item = "DirBuilder")]
217 pub struct DirBuilder {
218 inner: fs_imp::DirBuilder,
222 /// Read the entire contents of a file into a bytes vector.
224 /// This is a convenience function for using [`File::open`] and [`read_to_end`]
225 /// with fewer imports and without an intermediate variable.
227 /// [`read_to_end`]: Read::read_to_end
231 /// This function will return an error if `path` does not already exist.
232 /// Other errors may also be returned according to [`OpenOptions::open`].
234 /// It will also return an error if it encounters while reading an error
235 /// of a kind other than [`io::ErrorKind::Interrupted`].
241 /// use std::net::SocketAddr;
243 /// fn main() -> Result<(), Box<dyn std::error::Error + 'static>> {
244 /// let foo: SocketAddr = String::from_utf8_lossy(&fs::read("address.txt")?).parse()?;
248 #[stable(feature = "fs_read_write_bytes", since = "1.26.0")]
249 pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
250 fn inner(path: &Path) -> io::Result<Vec<u8>> {
251 let mut file = File::open(path)?;
252 let mut bytes = Vec::new();
253 file.read_to_end(&mut bytes)?;
259 /// Read the entire contents of a file into a string.
261 /// This is a convenience function for using [`File::open`] and [`read_to_string`]
262 /// with fewer imports and without an intermediate variable.
264 /// [`read_to_string`]: Read::read_to_string
268 /// This function will return an error if `path` does not already exist.
269 /// Other errors may also be returned according to [`OpenOptions::open`].
271 /// It will also return an error if it encounters while reading an error
272 /// of a kind other than [`io::ErrorKind::Interrupted`],
273 /// or if the contents of the file are not valid UTF-8.
279 /// use std::net::SocketAddr;
280 /// use std::error::Error;
282 /// fn main() -> Result<(), Box<dyn Error>> {
283 /// let foo: SocketAddr = fs::read_to_string("address.txt")?.parse()?;
287 #[stable(feature = "fs_read_write", since = "1.26.0")]
288 pub fn read_to_string<P: AsRef<Path>>(path: P) -> io::Result<String> {
289 fn inner(path: &Path) -> io::Result<String> {
290 let mut file = File::open(path)?;
291 let mut string = String::new();
292 file.read_to_string(&mut string)?;
298 /// Write a slice as the entire contents of a file.
300 /// This function will create a file if it does not exist,
301 /// and will entirely replace its contents if it does.
303 /// Depending on the platform, this function may fail if the
304 /// full directory path does not exist.
306 /// This is a convenience function for using [`File::create`] and [`write_all`]
307 /// with fewer imports.
309 /// [`write_all`]: Write::write_all
316 /// fn main() -> std::io::Result<()> {
317 /// fs::write("foo.txt", b"Lorem ipsum")?;
318 /// fs::write("bar.txt", "dolor sit")?;
322 #[stable(feature = "fs_read_write_bytes", since = "1.26.0")]
323 pub fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result<()> {
324 fn inner(path: &Path, contents: &[u8]) -> io::Result<()> {
325 File::create(path)?.write_all(contents)
327 inner(path.as_ref(), contents.as_ref())
331 /// Attempts to open a file in read-only mode.
333 /// See the [`OpenOptions::open`] method for more details.
337 /// This function will return an error if `path` does not already exist.
338 /// Other errors may also be returned according to [`OpenOptions::open`].
343 /// use std::fs::File;
345 /// fn main() -> std::io::Result<()> {
346 /// let mut f = File::open("foo.txt")?;
350 #[stable(feature = "rust1", since = "1.0.0")]
351 pub fn open<P: AsRef<Path>>(path: P) -> io::Result<File> {
352 OpenOptions::new().read(true).open(path.as_ref())
355 /// Opens a file in write-only mode.
357 /// This function will create a file if it does not exist,
358 /// and will truncate it if it does.
360 /// Depending on the platform, this function may fail if the
361 /// full directory path does not exist.
363 /// See the [`OpenOptions::open`] function for more details.
368 /// use std::fs::File;
370 /// fn main() -> std::io::Result<()> {
371 /// let mut f = File::create("foo.txt")?;
375 #[stable(feature = "rust1", since = "1.0.0")]
376 pub fn create<P: AsRef<Path>>(path: P) -> io::Result<File> {
377 OpenOptions::new().write(true).create(true).truncate(true).open(path.as_ref())
380 /// Returns a new OpenOptions object.
382 /// This function returns a new OpenOptions object that you can use to
383 /// open or create a file with specific options if `open()` or `create()`
384 /// are not appropriate.
386 /// It is equivalent to `OpenOptions::new()`, but allows you to write more
387 /// readable code. Instead of
388 /// `OpenOptions::new().append(true).open("example.log")`,
389 /// you can write `File::options().append(true).open("example.log")`. This
390 /// also avoids the need to import `OpenOptions`.
392 /// See the [`OpenOptions::new`] function for more details.
397 /// use std::fs::File;
399 /// fn main() -> std::io::Result<()> {
400 /// let mut f = File::options().append(true).open("example.log")?;
405 #[stable(feature = "with_options", since = "1.58.0")]
406 pub fn options() -> OpenOptions {
410 /// Attempts to sync all OS-internal metadata to disk.
412 /// This function will attempt to ensure that all in-memory data reaches the
413 /// filesystem before returning.
415 /// This can be used to handle errors that would otherwise only be caught
416 /// when the `File` is closed. Dropping a file will ignore errors in
417 /// synchronizing this in-memory data.
422 /// use std::fs::File;
423 /// use std::io::prelude::*;
425 /// fn main() -> std::io::Result<()> {
426 /// let mut f = File::create("foo.txt")?;
427 /// f.write_all(b"Hello, world!")?;
433 #[stable(feature = "rust1", since = "1.0.0")]
434 pub fn sync_all(&self) -> io::Result<()> {
438 /// This function is similar to [`sync_all`], except that it might not
439 /// synchronize file metadata to the filesystem.
441 /// This is intended for use cases that must synchronize content, but don't
442 /// need the metadata on disk. The goal of this method is to reduce disk
445 /// Note that some platforms may simply implement this in terms of
448 /// [`sync_all`]: File::sync_all
453 /// use std::fs::File;
454 /// use std::io::prelude::*;
456 /// fn main() -> std::io::Result<()> {
457 /// let mut f = File::create("foo.txt")?;
458 /// f.write_all(b"Hello, world!")?;
464 #[stable(feature = "rust1", since = "1.0.0")]
465 pub fn sync_data(&self) -> io::Result<()> {
466 self.inner.datasync()
469 /// Truncates or extends the underlying file, updating the size of
470 /// this file to become `size`.
472 /// If the `size` is less than the current file's size, then the file will
473 /// be shrunk. If it is greater than the current file's size, then the file
474 /// will be extended to `size` and have all of the intermediate data filled
477 /// The file's cursor isn't changed. In particular, if the cursor was at the
478 /// end and the file is shrunk using this operation, the cursor will now be
483 /// This function will return an error if the file is not opened for writing.
484 /// Also, std::io::ErrorKind::InvalidInput will be returned if the desired
485 /// length would cause an overflow due to the implementation specifics.
490 /// use std::fs::File;
492 /// fn main() -> std::io::Result<()> {
493 /// let mut f = File::create("foo.txt")?;
499 /// Note that this method alters the content of the underlying file, even
500 /// though it takes `&self` rather than `&mut self`.
501 #[stable(feature = "rust1", since = "1.0.0")]
502 pub fn set_len(&self, size: u64) -> io::Result<()> {
503 self.inner.truncate(size)
506 /// Queries metadata about the underlying file.
511 /// use std::fs::File;
513 /// fn main() -> std::io::Result<()> {
514 /// let mut f = File::open("foo.txt")?;
515 /// let metadata = f.metadata()?;
519 #[stable(feature = "rust1", since = "1.0.0")]
520 pub fn metadata(&self) -> io::Result<Metadata> {
521 self.inner.file_attr().map(Metadata)
524 /// Creates a new `File` instance that shares the same underlying file handle
525 /// as the existing `File` instance. Reads, writes, and seeks will affect
526 /// both `File` instances simultaneously.
530 /// Creates two handles for a file named `foo.txt`:
533 /// use std::fs::File;
535 /// fn main() -> std::io::Result<()> {
536 /// let mut file = File::open("foo.txt")?;
537 /// let file_copy = file.try_clone()?;
542 /// Assuming there’s a file named `foo.txt` with contents `abcdef\n`, create
543 /// two handles, seek one of them, and read the remaining bytes from the
547 /// use std::fs::File;
548 /// use std::io::SeekFrom;
549 /// use std::io::prelude::*;
551 /// fn main() -> std::io::Result<()> {
552 /// let mut file = File::open("foo.txt")?;
553 /// let mut file_copy = file.try_clone()?;
555 /// file.seek(SeekFrom::Start(3))?;
557 /// let mut contents = vec![];
558 /// file_copy.read_to_end(&mut contents)?;
559 /// assert_eq!(contents, b"def\n");
563 #[stable(feature = "file_try_clone", since = "1.9.0")]
564 pub fn try_clone(&self) -> io::Result<File> {
565 Ok(File { inner: self.inner.duplicate()? })
568 /// Changes the permissions on the underlying file.
570 /// # Platform-specific behavior
572 /// This function currently corresponds to the `fchmod` function on Unix and
573 /// the `SetFileInformationByHandle` function on Windows. Note that, this
574 /// [may change in the future][changes].
576 /// [changes]: io#platform-specific-behavior
580 /// This function will return an error if the user lacks permission change
581 /// attributes on the underlying file. It may also return an error in other
582 /// os-specific unspecified cases.
587 /// fn main() -> std::io::Result<()> {
588 /// use std::fs::File;
590 /// let file = File::open("foo.txt")?;
591 /// let mut perms = file.metadata()?.permissions();
592 /// perms.set_readonly(true);
593 /// file.set_permissions(perms)?;
598 /// Note that this method alters the permissions of the underlying file,
599 /// even though it takes `&self` rather than `&mut self`.
600 #[stable(feature = "set_permissions_atomic", since = "1.16.0")]
601 pub fn set_permissions(&self, perm: Permissions) -> io::Result<()> {
602 self.inner.set_permissions(perm.0)
605 /// Changes the timestamps of the underlying file.
607 /// # Platform-specific behavior
609 /// This function currently corresponds to the `futimens` function on Unix (falling back to
610 /// `futimes` on macOS before 10.13) and the `SetFileTime` function on Windows. Note that this
611 /// [may change in the future][changes].
613 /// [changes]: io#platform-specific-behavior
617 /// This function will return an error if the user lacks permission to change timestamps on the
618 /// underlying file. It may also return an error in other os-specific unspecified cases.
620 /// This function may return an error if the operating system lacks support to change one or
621 /// more of the timestamps set in the `FileTimes` structure.
626 /// #![feature(file_set_times)]
628 /// fn main() -> std::io::Result<()> {
629 /// use std::fs::{self, File, FileTimes};
631 /// let src = fs::metadata("src")?;
632 /// let dest = File::options().write(true).open("dest")?;
633 /// let times = FileTimes::new()
634 /// .set_accessed(src.accessed()?)
635 /// .set_modified(src.modified()?);
636 /// dest.set_times(times)?;
640 #[unstable(feature = "file_set_times", issue = "98245")]
641 #[doc(alias = "futimens")]
642 #[doc(alias = "futimes")]
643 #[doc(alias = "SetFileTime")]
644 pub fn set_times(&self, times: FileTimes) -> io::Result<()> {
645 self.inner.set_times(times.0)
648 /// Changes the modification time of the underlying file.
650 /// This is an alias for `set_times(FileTimes::new().set_modified(time))`.
651 #[unstable(feature = "file_set_times", issue = "98245")]
653 pub fn set_modified(&self, time: SystemTime) -> io::Result<()> {
654 self.set_times(FileTimes::new().set_modified(time))
658 // In addition to the `impl`s here, `File` also has `impl`s for
659 // `AsFd`/`From<OwnedFd>`/`Into<OwnedFd>` and
660 // `AsRawFd`/`IntoRawFd`/`FromRawFd`, on Unix and WASI, and
661 // `AsHandle`/`From<OwnedHandle>`/`Into<OwnedHandle>` and
662 // `AsRawHandle`/`IntoRawHandle`/`FromRawHandle` on Windows.
664 impl AsInner<fs_imp::File> for File {
665 fn as_inner(&self) -> &fs_imp::File {
669 impl FromInner<fs_imp::File> for File {
670 fn from_inner(f: fs_imp::File) -> File {
674 impl IntoInner<fs_imp::File> for File {
675 fn into_inner(self) -> fs_imp::File {
680 #[stable(feature = "rust1", since = "1.0.0")]
681 impl fmt::Debug for File {
682 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
687 /// Indicates how much extra capacity is needed to read the rest of the file.
688 fn buffer_capacity_required(mut file: &File) -> usize {
689 let size = file.metadata().map(|m| m.len()).unwrap_or(0);
690 let pos = file.stream_position().unwrap_or(0);
691 // Don't worry about `usize` overflow because reading will fail regardless
693 size.saturating_sub(pos) as usize
696 #[stable(feature = "rust1", since = "1.0.0")]
698 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
702 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
703 self.inner.read_vectored(bufs)
706 fn read_buf(&mut self, buf: &mut ReadBuf<'_>) -> io::Result<()> {
707 self.inner.read_buf(buf)
711 fn is_read_vectored(&self) -> bool {
712 self.inner.is_read_vectored()
715 // Reserves space in the buffer based on the file size when available.
716 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
717 buf.reserve(buffer_capacity_required(self));
718 io::default_read_to_end(self, buf)
721 // Reserves space in the buffer based on the file size when available.
722 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
723 buf.reserve(buffer_capacity_required(self));
724 io::default_read_to_string(self, buf)
727 #[stable(feature = "rust1", since = "1.0.0")]
728 impl Write for File {
729 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
730 self.inner.write(buf)
733 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
734 self.inner.write_vectored(bufs)
738 fn is_write_vectored(&self) -> bool {
739 self.inner.is_write_vectored()
742 fn flush(&mut self) -> io::Result<()> {
746 #[stable(feature = "rust1", since = "1.0.0")]
748 fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
752 #[stable(feature = "rust1", since = "1.0.0")]
753 impl Read for &File {
754 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
758 fn read_buf(&mut self, buf: &mut ReadBuf<'_>) -> io::Result<()> {
759 self.inner.read_buf(buf)
762 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
763 self.inner.read_vectored(bufs)
767 fn is_read_vectored(&self) -> bool {
768 self.inner.is_read_vectored()
771 // Reserves space in the buffer based on the file size when available.
772 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
773 buf.reserve(buffer_capacity_required(self));
774 io::default_read_to_end(self, buf)
777 // Reserves space in the buffer based on the file size when available.
778 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
779 buf.reserve(buffer_capacity_required(self));
780 io::default_read_to_string(self, buf)
783 #[stable(feature = "rust1", since = "1.0.0")]
784 impl Write for &File {
785 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
786 self.inner.write(buf)
789 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
790 self.inner.write_vectored(bufs)
794 fn is_write_vectored(&self) -> bool {
795 self.inner.is_write_vectored()
798 fn flush(&mut self) -> io::Result<()> {
802 #[stable(feature = "rust1", since = "1.0.0")]
803 impl Seek for &File {
804 fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
810 /// Creates a blank new set of options ready for configuration.
812 /// All options are initially set to `false`.
817 /// use std::fs::OpenOptions;
819 /// let mut options = OpenOptions::new();
820 /// let file = options.read(true).open("foo.txt");
822 #[stable(feature = "rust1", since = "1.0.0")]
824 pub fn new() -> Self {
825 OpenOptions(fs_imp::OpenOptions::new())
828 /// Sets the option for read access.
830 /// This option, when true, will indicate that the file should be
831 /// `read`-able if opened.
836 /// use std::fs::OpenOptions;
838 /// let file = OpenOptions::new().read(true).open("foo.txt");
840 #[stable(feature = "rust1", since = "1.0.0")]
841 pub fn read(&mut self, read: bool) -> &mut Self {
846 /// Sets the option for write access.
848 /// This option, when true, will indicate that the file should be
849 /// `write`-able if opened.
851 /// If the file already exists, any write calls on it will overwrite its
852 /// contents, without truncating it.
857 /// use std::fs::OpenOptions;
859 /// let file = OpenOptions::new().write(true).open("foo.txt");
861 #[stable(feature = "rust1", since = "1.0.0")]
862 pub fn write(&mut self, write: bool) -> &mut Self {
867 /// Sets the option for the append mode.
869 /// This option, when true, means that writes will append to a file instead
870 /// of overwriting previous contents.
871 /// Note that setting `.write(true).append(true)` has the same effect as
872 /// setting only `.append(true)`.
874 /// For most filesystems, the operating system guarantees that all writes are
875 /// atomic: no writes get mangled because another process writes at the same
878 /// One maybe obvious note when using append-mode: make sure that all data
879 /// that belongs together is written to the file in one operation. This
880 /// can be done by concatenating strings before passing them to [`write()`],
881 /// or using a buffered writer (with a buffer of adequate size),
882 /// and calling [`flush()`] when the message is complete.
884 /// If a file is opened with both read and append access, beware that after
885 /// opening, and after every write, the position for reading may be set at the
886 /// end of the file. So, before writing, save the current position (using
887 /// <code>[seek]\([SeekFrom]::[Current]\(0))</code>), and restore it before the next read.
891 /// This function doesn't create the file if it doesn't exist. Use the
892 /// [`OpenOptions::create`] method to do so.
894 /// [`write()`]: Write::write "io::Write::write"
895 /// [`flush()`]: Write::flush "io::Write::flush"
896 /// [seek]: Seek::seek "io::Seek::seek"
897 /// [Current]: SeekFrom::Current "io::SeekFrom::Current"
902 /// use std::fs::OpenOptions;
904 /// let file = OpenOptions::new().append(true).open("foo.txt");
906 #[stable(feature = "rust1", since = "1.0.0")]
907 pub fn append(&mut self, append: bool) -> &mut Self {
908 self.0.append(append);
912 /// Sets the option for truncating a previous file.
914 /// If a file is successfully opened with this option set it will truncate
915 /// the file to 0 length if it already exists.
917 /// The file must be opened with write access for truncate to work.
922 /// use std::fs::OpenOptions;
924 /// let file = OpenOptions::new().write(true).truncate(true).open("foo.txt");
926 #[stable(feature = "rust1", since = "1.0.0")]
927 pub fn truncate(&mut self, truncate: bool) -> &mut Self {
928 self.0.truncate(truncate);
932 /// Sets the option to create a new file, or open it if it already exists.
934 /// In order for the file to be created, [`OpenOptions::write`] or
935 /// [`OpenOptions::append`] access must be used.
940 /// use std::fs::OpenOptions;
942 /// let file = OpenOptions::new().write(true).create(true).open("foo.txt");
944 #[stable(feature = "rust1", since = "1.0.0")]
945 pub fn create(&mut self, create: bool) -> &mut Self {
946 self.0.create(create);
950 /// Sets the option to create a new file, failing if it already exists.
952 /// No file is allowed to exist at the target location, also no (dangling) symlink. In this
953 /// way, if the call succeeds, the file returned is guaranteed to be new.
955 /// This option is useful because it is atomic. Otherwise between checking
956 /// whether a file exists and creating a new one, the file may have been
957 /// created by another process (a TOCTOU race condition / attack).
959 /// If `.create_new(true)` is set, [`.create()`] and [`.truncate()`] are
962 /// The file must be opened with write or append access in order to create
965 /// [`.create()`]: OpenOptions::create
966 /// [`.truncate()`]: OpenOptions::truncate
971 /// use std::fs::OpenOptions;
973 /// let file = OpenOptions::new().write(true)
974 /// .create_new(true)
975 /// .open("foo.txt");
977 #[stable(feature = "expand_open_options2", since = "1.9.0")]
978 pub fn create_new(&mut self, create_new: bool) -> &mut Self {
979 self.0.create_new(create_new);
983 /// Opens a file at `path` with the options specified by `self`.
987 /// This function will return an error under a number of different
988 /// circumstances. Some of these error conditions are listed here, together
989 /// with their [`io::ErrorKind`]. The mapping to [`io::ErrorKind`]s is not
990 /// part of the compatibility contract of the function.
992 /// * [`NotFound`]: The specified file does not exist and neither `create`
993 /// or `create_new` is set.
994 /// * [`NotFound`]: One of the directory components of the file path does
996 /// * [`PermissionDenied`]: The user lacks permission to get the specified
997 /// access rights for the file.
998 /// * [`PermissionDenied`]: The user lacks permission to open one of the
999 /// directory components of the specified path.
1000 /// * [`AlreadyExists`]: `create_new` was specified and the file already
1002 /// * [`InvalidInput`]: Invalid combinations of open options (truncate
1003 /// without write access, no access mode set, etc.).
1005 /// The following errors don't match any existing [`io::ErrorKind`] at the moment:
1006 /// * One of the directory components of the specified file path
1007 /// was not, in fact, a directory.
1008 /// * Filesystem-level errors: full disk, write permission
1009 /// requested on a read-only file system, exceeded disk quota, too many
1010 /// open files, too long filename, too many symbolic links in the
1011 /// specified path (Unix-like systems only), etc.
1016 /// use std::fs::OpenOptions;
1018 /// let file = OpenOptions::new().read(true).open("foo.txt");
1021 /// [`AlreadyExists`]: io::ErrorKind::AlreadyExists
1022 /// [`InvalidInput`]: io::ErrorKind::InvalidInput
1023 /// [`NotFound`]: io::ErrorKind::NotFound
1024 /// [`PermissionDenied`]: io::ErrorKind::PermissionDenied
1025 #[stable(feature = "rust1", since = "1.0.0")]
1026 pub fn open<P: AsRef<Path>>(&self, path: P) -> io::Result<File> {
1027 self._open(path.as_ref())
1030 fn _open(&self, path: &Path) -> io::Result<File> {
1031 fs_imp::File::open(path, &self.0).map(|inner| File { inner })
1035 impl AsInner<fs_imp::OpenOptions> for OpenOptions {
1036 fn as_inner(&self) -> &fs_imp::OpenOptions {
1041 impl AsInnerMut<fs_imp::OpenOptions> for OpenOptions {
1042 fn as_inner_mut(&mut self) -> &mut fs_imp::OpenOptions {
1048 /// Returns the file type for this metadata.
1053 /// fn main() -> std::io::Result<()> {
1056 /// let metadata = fs::metadata("foo.txt")?;
1058 /// println!("{:?}", metadata.file_type());
1063 #[stable(feature = "file_type", since = "1.1.0")]
1064 pub fn file_type(&self) -> FileType {
1065 FileType(self.0.file_type())
1068 /// Returns `true` if this metadata is for a directory. The
1069 /// result is mutually exclusive to the result of
1070 /// [`Metadata::is_file`], and will be false for symlink metadata
1071 /// obtained from [`symlink_metadata`].
1076 /// fn main() -> std::io::Result<()> {
1079 /// let metadata = fs::metadata("foo.txt")?;
1081 /// assert!(!metadata.is_dir());
1086 #[stable(feature = "rust1", since = "1.0.0")]
1087 pub fn is_dir(&self) -> bool {
1088 self.file_type().is_dir()
1091 /// Returns `true` if this metadata is for a regular file. The
1092 /// result is mutually exclusive to the result of
1093 /// [`Metadata::is_dir`], and will be false for symlink metadata
1094 /// obtained from [`symlink_metadata`].
1096 /// When the goal is simply to read from (or write to) the source, the most
1097 /// reliable way to test the source can be read (or written to) is to open
1098 /// it. Only using `is_file` can break workflows like `diff <( prog_a )` on
1099 /// a Unix-like system for example. See [`File::open`] or
1100 /// [`OpenOptions::open`] for more information.
1107 /// fn main() -> std::io::Result<()> {
1108 /// let metadata = fs::metadata("foo.txt")?;
1110 /// assert!(metadata.is_file());
1115 #[stable(feature = "rust1", since = "1.0.0")]
1116 pub fn is_file(&self) -> bool {
1117 self.file_type().is_file()
1120 /// Returns `true` if this metadata is for a symbolic link.
1124 #[cfg_attr(unix, doc = "```no_run")]
1125 #[cfg_attr(not(unix), doc = "```ignore")]
1127 /// use std::path::Path;
1128 /// use std::os::unix::fs::symlink;
1130 /// fn main() -> std::io::Result<()> {
1131 /// let link_path = Path::new("link");
1132 /// symlink("/origin_does_not_exist/", link_path)?;
1134 /// let metadata = fs::symlink_metadata(link_path)?;
1136 /// assert!(metadata.is_symlink());
1141 #[stable(feature = "is_symlink", since = "1.58.0")]
1142 pub fn is_symlink(&self) -> bool {
1143 self.file_type().is_symlink()
1146 /// Returns the size of the file, in bytes, this metadata is for.
1153 /// fn main() -> std::io::Result<()> {
1154 /// let metadata = fs::metadata("foo.txt")?;
1156 /// assert_eq!(0, metadata.len());
1161 #[stable(feature = "rust1", since = "1.0.0")]
1162 pub fn len(&self) -> u64 {
1166 /// Returns the permissions of the file this metadata is for.
1173 /// fn main() -> std::io::Result<()> {
1174 /// let metadata = fs::metadata("foo.txt")?;
1176 /// assert!(!metadata.permissions().readonly());
1181 #[stable(feature = "rust1", since = "1.0.0")]
1182 pub fn permissions(&self) -> Permissions {
1183 Permissions(self.0.perm())
1186 /// Returns the last modification time listed in this metadata.
1188 /// The returned value corresponds to the `mtime` field of `stat` on Unix
1189 /// platforms and the `ftLastWriteTime` field on Windows platforms.
1193 /// This field might not be available on all platforms, and will return an
1194 /// `Err` on platforms where it is not available.
1201 /// fn main() -> std::io::Result<()> {
1202 /// let metadata = fs::metadata("foo.txt")?;
1204 /// if let Ok(time) = metadata.modified() {
1205 /// println!("{time:?}");
1207 /// println!("Not supported on this platform");
1212 #[stable(feature = "fs_time", since = "1.10.0")]
1213 pub fn modified(&self) -> io::Result<SystemTime> {
1214 self.0.modified().map(FromInner::from_inner)
1217 /// Returns the last access time of this metadata.
1219 /// The returned value corresponds to the `atime` field of `stat` on Unix
1220 /// platforms and the `ftLastAccessTime` field on Windows platforms.
1222 /// Note that not all platforms will keep this field update in a file's
1223 /// metadata, for example Windows has an option to disable updating this
1224 /// time when files are accessed and Linux similarly has `noatime`.
1228 /// This field might not be available on all platforms, and will return an
1229 /// `Err` on platforms where it is not available.
1236 /// fn main() -> std::io::Result<()> {
1237 /// let metadata = fs::metadata("foo.txt")?;
1239 /// if let Ok(time) = metadata.accessed() {
1240 /// println!("{time:?}");
1242 /// println!("Not supported on this platform");
1247 #[stable(feature = "fs_time", since = "1.10.0")]
1248 pub fn accessed(&self) -> io::Result<SystemTime> {
1249 self.0.accessed().map(FromInner::from_inner)
1252 /// Returns the creation time listed in this metadata.
1254 /// The returned value corresponds to the `btime` field of `statx` on
1255 /// Linux kernel starting from to 4.11, the `birthtime` field of `stat` on other
1256 /// Unix platforms, and the `ftCreationTime` field on Windows platforms.
1260 /// This field might not be available on all platforms, and will return an
1261 /// `Err` on platforms or filesystems where it is not available.
1268 /// fn main() -> std::io::Result<()> {
1269 /// let metadata = fs::metadata("foo.txt")?;
1271 /// if let Ok(time) = metadata.created() {
1272 /// println!("{time:?}");
1274 /// println!("Not supported on this platform or filesystem");
1279 #[stable(feature = "fs_time", since = "1.10.0")]
1280 pub fn created(&self) -> io::Result<SystemTime> {
1281 self.0.created().map(FromInner::from_inner)
1285 #[stable(feature = "std_debug", since = "1.16.0")]
1286 impl fmt::Debug for Metadata {
1287 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1288 f.debug_struct("Metadata")
1289 .field("file_type", &self.file_type())
1290 .field("is_dir", &self.is_dir())
1291 .field("is_file", &self.is_file())
1292 .field("permissions", &self.permissions())
1293 .field("modified", &self.modified())
1294 .field("accessed", &self.accessed())
1295 .field("created", &self.created())
1296 .finish_non_exhaustive()
1300 impl AsInner<fs_imp::FileAttr> for Metadata {
1301 fn as_inner(&self) -> &fs_imp::FileAttr {
1306 impl FromInner<fs_imp::FileAttr> for Metadata {
1307 fn from_inner(attr: fs_imp::FileAttr) -> Metadata {
1313 /// Create a new `FileTimes` with no times set.
1315 /// Using the resulting `FileTimes` in [`File::set_times`] will not modify any timestamps.
1316 #[unstable(feature = "file_set_times", issue = "98245")]
1317 pub fn new() -> Self {
1321 /// Set the last access time of a file.
1322 #[unstable(feature = "file_set_times", issue = "98245")]
1323 pub fn set_accessed(mut self, t: SystemTime) -> Self {
1324 self.0.set_accessed(t.into_inner());
1328 /// Set the last modified time of a file.
1329 #[unstable(feature = "file_set_times", issue = "98245")]
1330 pub fn set_modified(mut self, t: SystemTime) -> Self {
1331 self.0.set_modified(t.into_inner());
1337 /// Returns `true` if these permissions describe a readonly (unwritable) file.
1342 /// use std::fs::File;
1344 /// fn main() -> std::io::Result<()> {
1345 /// let mut f = File::create("foo.txt")?;
1346 /// let metadata = f.metadata()?;
1348 /// assert_eq!(false, metadata.permissions().readonly());
1352 #[must_use = "call `set_readonly` to modify the readonly flag"]
1353 #[stable(feature = "rust1", since = "1.0.0")]
1354 pub fn readonly(&self) -> bool {
1358 /// Modifies the readonly flag for this set of permissions. If the
1359 /// `readonly` argument is `true`, using the resulting `Permission` will
1360 /// update file permissions to forbid writing. Conversely, if it's `false`,
1361 /// using the resulting `Permission` will update file permissions to allow
1364 /// This operation does **not** modify the filesystem. To modify the
1365 /// filesystem use the [`set_permissions`] function.
1370 /// use std::fs::File;
1372 /// fn main() -> std::io::Result<()> {
1373 /// let f = File::create("foo.txt")?;
1374 /// let metadata = f.metadata()?;
1375 /// let mut permissions = metadata.permissions();
1377 /// permissions.set_readonly(true);
1379 /// // filesystem doesn't change
1380 /// assert_eq!(false, metadata.permissions().readonly());
1382 /// // just this particular `permissions`.
1383 /// assert_eq!(true, permissions.readonly());
1387 #[stable(feature = "rust1", since = "1.0.0")]
1388 pub fn set_readonly(&mut self, readonly: bool) {
1389 self.0.set_readonly(readonly)
1394 /// Tests whether this file type represents a directory. The
1395 /// result is mutually exclusive to the results of
1396 /// [`is_file`] and [`is_symlink`]; only zero or one of these
1399 /// [`is_file`]: FileType::is_file
1400 /// [`is_symlink`]: FileType::is_symlink
1405 /// fn main() -> std::io::Result<()> {
1408 /// let metadata = fs::metadata("foo.txt")?;
1409 /// let file_type = metadata.file_type();
1411 /// assert_eq!(file_type.is_dir(), false);
1416 #[stable(feature = "file_type", since = "1.1.0")]
1417 pub fn is_dir(&self) -> bool {
1421 /// Tests whether this file type represents a regular file.
1422 /// The result is mutually exclusive to the results of
1423 /// [`is_dir`] and [`is_symlink`]; only zero or one of these
1426 /// When the goal is simply to read from (or write to) the source, the most
1427 /// reliable way to test the source can be read (or written to) is to open
1428 /// it. Only using `is_file` can break workflows like `diff <( prog_a )` on
1429 /// a Unix-like system for example. See [`File::open`] or
1430 /// [`OpenOptions::open`] for more information.
1432 /// [`is_dir`]: FileType::is_dir
1433 /// [`is_symlink`]: FileType::is_symlink
1438 /// fn main() -> std::io::Result<()> {
1441 /// let metadata = fs::metadata("foo.txt")?;
1442 /// let file_type = metadata.file_type();
1444 /// assert_eq!(file_type.is_file(), true);
1449 #[stable(feature = "file_type", since = "1.1.0")]
1450 pub fn is_file(&self) -> bool {
1454 /// Tests whether this file type represents a symbolic link.
1455 /// The result is mutually exclusive to the results of
1456 /// [`is_dir`] and [`is_file`]; only zero or one of these
1459 /// The underlying [`Metadata`] struct needs to be retrieved
1460 /// with the [`fs::symlink_metadata`] function and not the
1461 /// [`fs::metadata`] function. The [`fs::metadata`] function
1462 /// follows symbolic links, so [`is_symlink`] would always
1463 /// return `false` for the target file.
1465 /// [`fs::metadata`]: metadata
1466 /// [`fs::symlink_metadata`]: symlink_metadata
1467 /// [`is_dir`]: FileType::is_dir
1468 /// [`is_file`]: FileType::is_file
1469 /// [`is_symlink`]: FileType::is_symlink
1476 /// fn main() -> std::io::Result<()> {
1477 /// let metadata = fs::symlink_metadata("foo.txt")?;
1478 /// let file_type = metadata.file_type();
1480 /// assert_eq!(file_type.is_symlink(), false);
1485 #[stable(feature = "file_type", since = "1.1.0")]
1486 pub fn is_symlink(&self) -> bool {
1491 impl AsInner<fs_imp::FileType> for FileType {
1492 fn as_inner(&self) -> &fs_imp::FileType {
1497 impl FromInner<fs_imp::FilePermissions> for Permissions {
1498 fn from_inner(f: fs_imp::FilePermissions) -> Permissions {
1503 impl AsInner<fs_imp::FilePermissions> for Permissions {
1504 fn as_inner(&self) -> &fs_imp::FilePermissions {
1509 #[stable(feature = "rust1", since = "1.0.0")]
1510 impl Iterator for ReadDir {
1511 type Item = io::Result<DirEntry>;
1513 fn next(&mut self) -> Option<io::Result<DirEntry>> {
1514 self.0.next().map(|entry| entry.map(DirEntry))
1519 /// Returns the full path to the file that this entry represents.
1521 /// The full path is created by joining the original path to `read_dir`
1522 /// with the filename of this entry.
1529 /// fn main() -> std::io::Result<()> {
1530 /// for entry in fs::read_dir(".")? {
1531 /// let dir = entry?;
1532 /// println!("{:?}", dir.path());
1538 /// This prints output like:
1541 /// "./whatever.txt"
1543 /// "./hello_world.rs"
1546 /// The exact text, of course, depends on what files you have in `.`.
1548 #[stable(feature = "rust1", since = "1.0.0")]
1549 pub fn path(&self) -> PathBuf {
1553 /// Returns the metadata for the file that this entry points at.
1555 /// This function will not traverse symlinks if this entry points at a
1556 /// symlink. To traverse symlinks use [`fs::metadata`] or [`fs::File::metadata`].
1558 /// [`fs::metadata`]: metadata
1559 /// [`fs::File::metadata`]: File::metadata
1561 /// # Platform-specific behavior
1563 /// On Windows this function is cheap to call (no extra system calls
1564 /// needed), but on Unix platforms this function is the equivalent of
1565 /// calling `symlink_metadata` on the path.
1572 /// if let Ok(entries) = fs::read_dir(".") {
1573 /// for entry in entries {
1574 /// if let Ok(entry) = entry {
1575 /// // Here, `entry` is a `DirEntry`.
1576 /// if let Ok(metadata) = entry.metadata() {
1577 /// // Now let's show our entry's permissions!
1578 /// println!("{:?}: {:?}", entry.path(), metadata.permissions());
1580 /// println!("Couldn't get metadata for {:?}", entry.path());
1586 #[stable(feature = "dir_entry_ext", since = "1.1.0")]
1587 pub fn metadata(&self) -> io::Result<Metadata> {
1588 self.0.metadata().map(Metadata)
1591 /// Returns the file type for the file that this entry points at.
1593 /// This function will not traverse symlinks if this entry points at a
1596 /// # Platform-specific behavior
1598 /// On Windows and most Unix platforms this function is free (no extra
1599 /// system calls needed), but some Unix platforms may require the equivalent
1600 /// call to `symlink_metadata` to learn about the target file type.
1607 /// if let Ok(entries) = fs::read_dir(".") {
1608 /// for entry in entries {
1609 /// if let Ok(entry) = entry {
1610 /// // Here, `entry` is a `DirEntry`.
1611 /// if let Ok(file_type) = entry.file_type() {
1612 /// // Now let's show our entry's file type!
1613 /// println!("{:?}: {:?}", entry.path(), file_type);
1615 /// println!("Couldn't get file type for {:?}", entry.path());
1621 #[stable(feature = "dir_entry_ext", since = "1.1.0")]
1622 pub fn file_type(&self) -> io::Result<FileType> {
1623 self.0.file_type().map(FileType)
1626 /// Returns the bare file name of this directory entry without any other
1627 /// leading path component.
1634 /// if let Ok(entries) = fs::read_dir(".") {
1635 /// for entry in entries {
1636 /// if let Ok(entry) = entry {
1637 /// // Here, `entry` is a `DirEntry`.
1638 /// println!("{:?}", entry.file_name());
1644 #[stable(feature = "dir_entry_ext", since = "1.1.0")]
1645 pub fn file_name(&self) -> OsString {
1650 #[stable(feature = "dir_entry_debug", since = "1.13.0")]
1651 impl fmt::Debug for DirEntry {
1652 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1653 f.debug_tuple("DirEntry").field(&self.path()).finish()
1657 impl AsInner<fs_imp::DirEntry> for DirEntry {
1658 fn as_inner(&self) -> &fs_imp::DirEntry {
1663 /// Removes a file from the filesystem.
1665 /// Note that there is no
1666 /// guarantee that the file is immediately deleted (e.g., depending on
1667 /// platform, other open file descriptors may prevent immediate removal).
1669 /// # Platform-specific behavior
1671 /// This function currently corresponds to the `unlink` function on Unix
1672 /// and the `DeleteFile` function on Windows.
1673 /// Note that, this [may change in the future][changes].
1675 /// [changes]: io#platform-specific-behavior
1679 /// This function will return an error in the following situations, but is not
1680 /// limited to just these cases:
1682 /// * `path` points to a directory.
1683 /// * The file doesn't exist.
1684 /// * The user lacks permissions to remove the file.
1691 /// fn main() -> std::io::Result<()> {
1692 /// fs::remove_file("a.txt")?;
1696 #[stable(feature = "rust1", since = "1.0.0")]
1697 pub fn remove_file<P: AsRef<Path>>(path: P) -> io::Result<()> {
1698 fs_imp::unlink(path.as_ref())
1701 /// Given a path, query the file system to get information about a file,
1704 /// This function will traverse symbolic links to query information about the
1705 /// destination file.
1707 /// # Platform-specific behavior
1709 /// This function currently corresponds to the `stat` function on Unix
1710 /// and the `GetFileInformationByHandle` function on Windows.
1711 /// Note that, this [may change in the future][changes].
1713 /// [changes]: io#platform-specific-behavior
1717 /// This function will return an error in the following situations, but is not
1718 /// limited to just these cases:
1720 /// * The user lacks permissions to perform `metadata` call on `path`.
1721 /// * `path` does not exist.
1728 /// fn main() -> std::io::Result<()> {
1729 /// let attr = fs::metadata("/some/file/path.txt")?;
1730 /// // inspect attr ...
1734 #[stable(feature = "rust1", since = "1.0.0")]
1735 pub fn metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
1736 fs_imp::stat(path.as_ref()).map(Metadata)
1739 /// Query the metadata about a file without following symlinks.
1741 /// # Platform-specific behavior
1743 /// This function currently corresponds to the `lstat` function on Unix
1744 /// and the `GetFileInformationByHandle` function on Windows.
1745 /// Note that, this [may change in the future][changes].
1747 /// [changes]: io#platform-specific-behavior
1751 /// This function will return an error in the following situations, but is not
1752 /// limited to just these cases:
1754 /// * The user lacks permissions to perform `metadata` call on `path`.
1755 /// * `path` does not exist.
1762 /// fn main() -> std::io::Result<()> {
1763 /// let attr = fs::symlink_metadata("/some/file/path.txt")?;
1764 /// // inspect attr ...
1768 #[stable(feature = "symlink_metadata", since = "1.1.0")]
1769 pub fn symlink_metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
1770 fs_imp::lstat(path.as_ref()).map(Metadata)
1773 /// Rename a file or directory to a new name, replacing the original file if
1774 /// `to` already exists.
1776 /// This will not work if the new name is on a different mount point.
1778 /// # Platform-specific behavior
1780 /// This function currently corresponds to the `rename` function on Unix
1781 /// and the `MoveFileEx` function with the `MOVEFILE_REPLACE_EXISTING` flag on Windows.
1783 /// Because of this, the behavior when both `from` and `to` exist differs. On
1784 /// Unix, if `from` is a directory, `to` must also be an (empty) directory. If
1785 /// `from` is not a directory, `to` must also be not a directory. In contrast,
1786 /// on Windows, `from` can be anything, but `to` must *not* be a directory.
1788 /// Note that, this [may change in the future][changes].
1790 /// [changes]: io#platform-specific-behavior
1794 /// This function will return an error in the following situations, but is not
1795 /// limited to just these cases:
1797 /// * `from` does not exist.
1798 /// * The user lacks permissions to view contents.
1799 /// * `from` and `to` are on separate filesystems.
1806 /// fn main() -> std::io::Result<()> {
1807 /// fs::rename("a.txt", "b.txt")?; // Rename a.txt to b.txt
1811 #[stable(feature = "rust1", since = "1.0.0")]
1812 pub fn rename<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()> {
1813 fs_imp::rename(from.as_ref(), to.as_ref())
1816 /// Copies the contents of one file to another. This function will also
1817 /// copy the permission bits of the original file to the destination file.
1819 /// This function will **overwrite** the contents of `to`.
1821 /// Note that if `from` and `to` both point to the same file, then the file
1822 /// will likely get truncated by this operation.
1824 /// On success, the total number of bytes copied is returned and it is equal to
1825 /// the length of the `to` file as reported by `metadata`.
1827 /// If you’re wanting to copy the contents of one file to another and you’re
1828 /// working with [`File`]s, see the [`io::copy()`] function.
1830 /// # Platform-specific behavior
1832 /// This function currently corresponds to the `open` function in Unix
1833 /// with `O_RDONLY` for `from` and `O_WRONLY`, `O_CREAT`, and `O_TRUNC` for `to`.
1834 /// `O_CLOEXEC` is set for returned file descriptors.
1836 /// On Linux (including Android), this function attempts to use `copy_file_range(2)`,
1837 /// and falls back to reading and writing if that is not possible.
1839 /// On Windows, this function currently corresponds to `CopyFileEx`. Alternate
1840 /// NTFS streams are copied but only the size of the main stream is returned by
1843 /// On MacOS, this function corresponds to `fclonefileat` and `fcopyfile`.
1845 /// Note that platform-specific behavior [may change in the future][changes].
1847 /// [changes]: io#platform-specific-behavior
1851 /// This function will return an error in the following situations, but is not
1852 /// limited to just these cases:
1854 /// * `from` is neither a regular file nor a symlink to a regular file.
1855 /// * `from` does not exist.
1856 /// * The current process does not have the permission rights to read
1857 /// `from` or write `to`.
1864 /// fn main() -> std::io::Result<()> {
1865 /// fs::copy("foo.txt", "bar.txt")?; // Copy foo.txt to bar.txt
1869 #[stable(feature = "rust1", since = "1.0.0")]
1870 pub fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<u64> {
1871 fs_imp::copy(from.as_ref(), to.as_ref())
1874 /// Creates a new hard link on the filesystem.
1876 /// The `link` path will be a link pointing to the `original` path. Note that
1877 /// systems often require these two paths to both be located on the same
1880 /// If `original` names a symbolic link, it is platform-specific whether the
1881 /// symbolic link is followed. On platforms where it's possible to not follow
1882 /// it, it is not followed, and the created hard link points to the symbolic
1885 /// # Platform-specific behavior
1887 /// This function currently corresponds the `CreateHardLink` function on Windows.
1888 /// On most Unix systems, it corresponds to the `linkat` function with no flags.
1889 /// On Android, VxWorks, and Redox, it instead corresponds to the `link` function.
1890 /// On MacOS, it uses the `linkat` function if it is available, but on very old
1891 /// systems where `linkat` is not available, `link` is selected at runtime instead.
1892 /// Note that, this [may change in the future][changes].
1894 /// [changes]: io#platform-specific-behavior
1898 /// This function will return an error in the following situations, but is not
1899 /// limited to just these cases:
1901 /// * The `original` path is not a file or doesn't exist.
1908 /// fn main() -> std::io::Result<()> {
1909 /// fs::hard_link("a.txt", "b.txt")?; // Hard link a.txt to b.txt
1913 #[stable(feature = "rust1", since = "1.0.0")]
1914 pub fn hard_link<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Result<()> {
1915 fs_imp::link(original.as_ref(), link.as_ref())
1918 /// Creates a new symbolic link on the filesystem.
1920 /// The `link` path will be a symbolic link pointing to the `original` path.
1921 /// On Windows, this will be a file symlink, not a directory symlink;
1922 /// for this reason, the platform-specific [`std::os::unix::fs::symlink`]
1923 /// and [`std::os::windows::fs::symlink_file`] or [`symlink_dir`] should be
1924 /// used instead to make the intent explicit.
1926 /// [`std::os::unix::fs::symlink`]: crate::os::unix::fs::symlink
1927 /// [`std::os::windows::fs::symlink_file`]: crate::os::windows::fs::symlink_file
1928 /// [`symlink_dir`]: crate::os::windows::fs::symlink_dir
1935 /// fn main() -> std::io::Result<()> {
1936 /// fs::soft_link("a.txt", "b.txt")?;
1940 #[stable(feature = "rust1", since = "1.0.0")]
1943 note = "replaced with std::os::unix::fs::symlink and \
1944 std::os::windows::fs::{symlink_file, symlink_dir}"
1946 pub fn soft_link<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Result<()> {
1947 fs_imp::symlink(original.as_ref(), link.as_ref())
1950 /// Reads a symbolic link, returning the file that the link points to.
1952 /// # Platform-specific behavior
1954 /// This function currently corresponds to the `readlink` function on Unix
1955 /// and the `CreateFile` function with `FILE_FLAG_OPEN_REPARSE_POINT` and
1956 /// `FILE_FLAG_BACKUP_SEMANTICS` flags on Windows.
1957 /// Note that, this [may change in the future][changes].
1959 /// [changes]: io#platform-specific-behavior
1963 /// This function will return an error in the following situations, but is not
1964 /// limited to just these cases:
1966 /// * `path` is not a symbolic link.
1967 /// * `path` does not exist.
1974 /// fn main() -> std::io::Result<()> {
1975 /// let path = fs::read_link("a.txt")?;
1979 #[stable(feature = "rust1", since = "1.0.0")]
1980 pub fn read_link<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
1981 fs_imp::readlink(path.as_ref())
1984 /// Returns the canonical, absolute form of a path with all intermediate
1985 /// components normalized and symbolic links resolved.
1987 /// # Platform-specific behavior
1989 /// This function currently corresponds to the `realpath` function on Unix
1990 /// and the `CreateFile` and `GetFinalPathNameByHandle` functions on Windows.
1991 /// Note that, this [may change in the future][changes].
1993 /// On Windows, this converts the path to use [extended length path][path]
1994 /// syntax, which allows your program to use longer path names, but means you
1995 /// can only join backslash-delimited paths to it, and it may be incompatible
1996 /// with other applications (if passed to the application on the command-line,
1997 /// or written to a file another application may read).
1999 /// [changes]: io#platform-specific-behavior
2000 /// [path]: https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file
2004 /// This function will return an error in the following situations, but is not
2005 /// limited to just these cases:
2007 /// * `path` does not exist.
2008 /// * A non-final component in path is not a directory.
2015 /// fn main() -> std::io::Result<()> {
2016 /// let path = fs::canonicalize("../a/../foo.txt")?;
2020 #[doc(alias = "realpath")]
2021 #[doc(alias = "GetFinalPathNameByHandle")]
2022 #[stable(feature = "fs_canonicalize", since = "1.5.0")]
2023 pub fn canonicalize<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
2024 fs_imp::canonicalize(path.as_ref())
2027 /// Creates a new, empty directory at the provided path
2029 /// # Platform-specific behavior
2031 /// This function currently corresponds to the `mkdir` function on Unix
2032 /// and the `CreateDirectory` function on Windows.
2033 /// Note that, this [may change in the future][changes].
2035 /// [changes]: io#platform-specific-behavior
2037 /// **NOTE**: If a parent of the given path doesn't exist, this function will
2038 /// return an error. To create a directory and all its missing parents at the
2039 /// same time, use the [`create_dir_all`] function.
2043 /// This function will return an error in the following situations, but is not
2044 /// limited to just these cases:
2046 /// * User lacks permissions to create directory at `path`.
2047 /// * A parent of the given path doesn't exist. (To create a directory and all
2048 /// its missing parents at the same time, use the [`create_dir_all`]
2050 /// * `path` already exists.
2057 /// fn main() -> std::io::Result<()> {
2058 /// fs::create_dir("/some/dir")?;
2062 #[doc(alias = "mkdir")]
2063 #[stable(feature = "rust1", since = "1.0.0")]
2064 pub fn create_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
2065 DirBuilder::new().create(path.as_ref())
2068 /// Recursively create a directory and all of its parent components if they
2071 /// # Platform-specific behavior
2073 /// This function currently corresponds to the `mkdir` function on Unix
2074 /// and the `CreateDirectory` function on Windows.
2075 /// Note that, this [may change in the future][changes].
2077 /// [changes]: io#platform-specific-behavior
2081 /// This function will return an error in the following situations, but is not
2082 /// limited to just these cases:
2084 /// * If any directory in the path specified by `path`
2085 /// does not already exist and it could not be created otherwise. The specific
2086 /// error conditions for when a directory is being created (after it is
2087 /// determined to not exist) are outlined by [`fs::create_dir`].
2089 /// Notable exception is made for situations where any of the directories
2090 /// specified in the `path` could not be created as it was being created concurrently.
2091 /// Such cases are considered to be successful. That is, calling `create_dir_all`
2092 /// concurrently from multiple threads or processes is guaranteed not to fail
2093 /// due to a race condition with itself.
2095 /// [`fs::create_dir`]: create_dir
2102 /// fn main() -> std::io::Result<()> {
2103 /// fs::create_dir_all("/some/dir")?;
2107 #[stable(feature = "rust1", since = "1.0.0")]
2108 pub fn create_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
2109 DirBuilder::new().recursive(true).create(path.as_ref())
2112 /// Removes an empty directory.
2114 /// # Platform-specific behavior
2116 /// This function currently corresponds to the `rmdir` function on Unix
2117 /// and the `RemoveDirectory` function on Windows.
2118 /// Note that, this [may change in the future][changes].
2120 /// [changes]: io#platform-specific-behavior
2124 /// This function will return an error in the following situations, but is not
2125 /// limited to just these cases:
2127 /// * `path` doesn't exist.
2128 /// * `path` isn't a directory.
2129 /// * The user lacks permissions to remove the directory at the provided `path`.
2130 /// * The directory isn't empty.
2137 /// fn main() -> std::io::Result<()> {
2138 /// fs::remove_dir("/some/dir")?;
2142 #[doc(alias = "rmdir")]
2143 #[stable(feature = "rust1", since = "1.0.0")]
2144 pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
2145 fs_imp::rmdir(path.as_ref())
2148 /// Removes a directory at this path, after removing all its contents. Use
2151 /// This function does **not** follow symbolic links and it will simply remove the
2152 /// symbolic link itself.
2154 /// # Platform-specific behavior
2156 /// This function currently corresponds to `openat`, `fdopendir`, `unlinkat` and `lstat` functions
2157 /// on Unix (except for macOS before version 10.10 and REDOX) and the `CreateFileW`,
2158 /// `GetFileInformationByHandleEx`, `SetFileInformationByHandle`, and `NtCreateFile` functions on
2159 /// Windows. Note that, this [may change in the future][changes].
2161 /// [changes]: io#platform-specific-behavior
2163 /// On macOS before version 10.10 and REDOX, as well as when running in Miri for any target, this
2164 /// function is not protected against time-of-check to time-of-use (TOCTOU) race conditions, and
2165 /// should not be used in security-sensitive code on those platforms. All other platforms are
2170 /// See [`fs::remove_file`] and [`fs::remove_dir`].
2172 /// [`fs::remove_file`]: remove_file
2173 /// [`fs::remove_dir`]: remove_dir
2180 /// fn main() -> std::io::Result<()> {
2181 /// fs::remove_dir_all("/some/dir")?;
2185 #[stable(feature = "rust1", since = "1.0.0")]
2186 pub fn remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
2187 fs_imp::remove_dir_all(path.as_ref())
2190 /// Returns an iterator over the entries within a directory.
2192 /// The iterator will yield instances of <code>[io::Result]<[DirEntry]></code>.
2193 /// New errors may be encountered after an iterator is initially constructed.
2194 /// Entries for the current and parent directories (typically `.` and `..`) are
2197 /// # Platform-specific behavior
2199 /// This function currently corresponds to the `opendir` function on Unix
2200 /// and the `FindFirstFile` function on Windows. Advancing the iterator
2201 /// currently corresponds to `readdir` on Unix and `FindNextFile` on Windows.
2202 /// Note that, this [may change in the future][changes].
2204 /// [changes]: io#platform-specific-behavior
2206 /// The order in which this iterator returns entries is platform and filesystem
2211 /// This function will return an error in the following situations, but is not
2212 /// limited to just these cases:
2214 /// * The provided `path` doesn't exist.
2215 /// * The process lacks permissions to view the contents.
2216 /// * The `path` points at a non-directory file.
2222 /// use std::fs::{self, DirEntry};
2223 /// use std::path::Path;
2225 /// // one possible implementation of walking a directory only visiting files
2226 /// fn visit_dirs(dir: &Path, cb: &dyn Fn(&DirEntry)) -> io::Result<()> {
2227 /// if dir.is_dir() {
2228 /// for entry in fs::read_dir(dir)? {
2229 /// let entry = entry?;
2230 /// let path = entry.path();
2231 /// if path.is_dir() {
2232 /// visit_dirs(&path, cb)?;
2243 /// use std::{fs, io};
2245 /// fn main() -> io::Result<()> {
2246 /// let mut entries = fs::read_dir(".")?
2247 /// .map(|res| res.map(|e| e.path()))
2248 /// .collect::<Result<Vec<_>, io::Error>>()?;
2250 /// // The order in which `read_dir` returns entries is not guaranteed. If reproducible
2251 /// // ordering is required the entries should be explicitly sorted.
2255 /// // The entries have now been sorted by their path.
2260 #[stable(feature = "rust1", since = "1.0.0")]
2261 pub fn read_dir<P: AsRef<Path>>(path: P) -> io::Result<ReadDir> {
2262 fs_imp::readdir(path.as_ref()).map(ReadDir)
2265 /// Changes the permissions found on a file or a directory.
2267 /// # Platform-specific behavior
2269 /// This function currently corresponds to the `chmod` function on Unix
2270 /// and the `SetFileAttributes` function on Windows.
2271 /// Note that, this [may change in the future][changes].
2273 /// [changes]: io#platform-specific-behavior
2277 /// This function will return an error in the following situations, but is not
2278 /// limited to just these cases:
2280 /// * `path` does not exist.
2281 /// * The user lacks the permission to change attributes of the file.
2288 /// fn main() -> std::io::Result<()> {
2289 /// let mut perms = fs::metadata("foo.txt")?.permissions();
2290 /// perms.set_readonly(true);
2291 /// fs::set_permissions("foo.txt", perms)?;
2295 #[stable(feature = "set_permissions", since = "1.1.0")]
2296 pub fn set_permissions<P: AsRef<Path>>(path: P, perm: Permissions) -> io::Result<()> {
2297 fs_imp::set_perm(path.as_ref(), perm.0)
2301 /// Creates a new set of options with default mode/security settings for all
2302 /// platforms and also non-recursive.
2307 /// use std::fs::DirBuilder;
2309 /// let builder = DirBuilder::new();
2311 #[stable(feature = "dir_builder", since = "1.6.0")]
2313 pub fn new() -> DirBuilder {
2314 DirBuilder { inner: fs_imp::DirBuilder::new(), recursive: false }
2317 /// Indicates that directories should be created recursively, creating all
2318 /// parent directories. Parents that do not exist are created with the same
2319 /// security and permissions settings.
2321 /// This option defaults to `false`.
2326 /// use std::fs::DirBuilder;
2328 /// let mut builder = DirBuilder::new();
2329 /// builder.recursive(true);
2331 #[stable(feature = "dir_builder", since = "1.6.0")]
2332 pub fn recursive(&mut self, recursive: bool) -> &mut Self {
2333 self.recursive = recursive;
2337 /// Creates the specified directory with the options configured in this
2340 /// It is considered an error if the directory already exists unless
2341 /// recursive mode is enabled.
2346 /// use std::fs::{self, DirBuilder};
2348 /// let path = "/tmp/foo/bar/baz";
2349 /// DirBuilder::new()
2350 /// .recursive(true)
2351 /// .create(path).unwrap();
2353 /// assert!(fs::metadata(path).unwrap().is_dir());
2355 #[stable(feature = "dir_builder", since = "1.6.0")]
2356 pub fn create<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
2357 self._create(path.as_ref())
2360 fn _create(&self, path: &Path) -> io::Result<()> {
2361 if self.recursive { self.create_dir_all(path) } else { self.inner.mkdir(path) }
2364 fn create_dir_all(&self, path: &Path) -> io::Result<()> {
2365 if path == Path::new("") {
2369 match self.inner.mkdir(path) {
2370 Ok(()) => return Ok(()),
2371 Err(ref e) if e.kind() == io::ErrorKind::NotFound => {}
2372 Err(_) if path.is_dir() => return Ok(()),
2373 Err(e) => return Err(e),
2375 match path.parent() {
2376 Some(p) => self.create_dir_all(p)?,
2378 return Err(io::const_io_error!(
2379 io::ErrorKind::Uncategorized,
2380 "failed to create whole tree",
2384 match self.inner.mkdir(path) {
2386 Err(_) if path.is_dir() => Ok(()),
2392 impl AsInnerMut<fs_imp::DirBuilder> for DirBuilder {
2393 fn as_inner_mut(&mut self) -> &mut fs_imp::DirBuilder {
2398 /// Returns `Ok(true)` if the path points at an existing entity.
2400 /// This function will traverse symbolic links to query information about the
2401 /// destination file. In case of broken symbolic links this will return `Ok(false)`.
2403 /// As opposed to the [`Path::exists`] method, this one doesn't silently ignore errors
2404 /// unrelated to the path not existing. (E.g. it will return `Err(_)` in case of permission
2405 /// denied on some of the parent directories.)
2407 /// Note that while this avoids some pitfalls of the `exists()` method, it still can not
2408 /// prevent time-of-check to time-of-use (TOCTOU) bugs. You should only use it in scenarios
2409 /// where those bugs are not an issue.
2414 /// #![feature(fs_try_exists)]
2417 /// assert!(!fs::try_exists("does_not_exist.txt").expect("Can't check existence of file does_not_exist.txt"));
2418 /// assert!(fs::try_exists("/root/secret_file.txt").is_err());
2421 /// [`Path::exists`]: crate::path::Path::exists
2422 // FIXME: stabilization should modify documentation of `exists()` to recommend this method
2424 #[unstable(feature = "fs_try_exists", issue = "83186")]
2426 pub fn try_exists<P: AsRef<Path>>(path: P) -> io::Result<bool> {
2427 fs_imp::try_exists(path.as_ref())