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 permissions on a file.
189 /// This module only currently provides one bit of information,
190 /// [`Permissions::readonly`], which is exposed on all currently supported
191 /// platforms. Unix-specific functionality, such as mode bits, is available
192 /// through the [`PermissionsExt`] trait.
194 /// [`PermissionsExt`]: crate::os::unix::fs::PermissionsExt
195 #[derive(Clone, PartialEq, Eq, Debug)]
196 #[stable(feature = "rust1", since = "1.0.0")]
197 pub struct Permissions(fs_imp::FilePermissions);
199 /// A structure representing a type of file with accessors for each file type.
200 /// It is returned by [`Metadata::file_type`] method.
201 #[stable(feature = "file_type", since = "1.1.0")]
202 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
203 #[cfg_attr(not(test), rustc_diagnostic_item = "FileType")]
204 pub struct FileType(fs_imp::FileType);
206 /// A builder used to create directories in various manners.
208 /// This builder also supports platform-specific options.
209 #[stable(feature = "dir_builder", since = "1.6.0")]
210 #[cfg_attr(not(test), rustc_diagnostic_item = "DirBuilder")]
212 pub struct DirBuilder {
213 inner: fs_imp::DirBuilder,
217 /// Read the entire contents of a file into a bytes vector.
219 /// This is a convenience function for using [`File::open`] and [`read_to_end`]
220 /// with fewer imports and without an intermediate variable.
222 /// [`read_to_end`]: Read::read_to_end
226 /// This function will return an error if `path` does not already exist.
227 /// Other errors may also be returned according to [`OpenOptions::open`].
229 /// It will also return an error if it encounters while reading an error
230 /// of a kind other than [`io::ErrorKind::Interrupted`].
236 /// use std::net::SocketAddr;
238 /// fn main() -> Result<(), Box<dyn std::error::Error + 'static>> {
239 /// let foo: SocketAddr = String::from_utf8_lossy(&fs::read("address.txt")?).parse()?;
243 #[stable(feature = "fs_read_write_bytes", since = "1.26.0")]
244 pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
245 fn inner(path: &Path) -> io::Result<Vec<u8>> {
246 let mut file = File::open(path)?;
247 let mut bytes = Vec::new();
248 file.read_to_end(&mut bytes)?;
254 /// Read the entire contents of a file into a string.
256 /// This is a convenience function for using [`File::open`] and [`read_to_string`]
257 /// with fewer imports and without an intermediate variable.
259 /// [`read_to_string`]: Read::read_to_string
263 /// This function will return an error if `path` does not already exist.
264 /// Other errors may also be returned according to [`OpenOptions::open`].
266 /// It will also return an error if it encounters while reading an error
267 /// of a kind other than [`io::ErrorKind::Interrupted`],
268 /// or if the contents of the file are not valid UTF-8.
274 /// use std::net::SocketAddr;
275 /// use std::error::Error;
277 /// fn main() -> Result<(), Box<dyn Error>> {
278 /// let foo: SocketAddr = fs::read_to_string("address.txt")?.parse()?;
282 #[stable(feature = "fs_read_write", since = "1.26.0")]
283 pub fn read_to_string<P: AsRef<Path>>(path: P) -> io::Result<String> {
284 fn inner(path: &Path) -> io::Result<String> {
285 let mut file = File::open(path)?;
286 let mut string = String::new();
287 file.read_to_string(&mut string)?;
293 /// Write a slice as the entire contents of a file.
295 /// This function will create a file if it does not exist,
296 /// and will entirely replace its contents if it does.
298 /// Depending on the platform, this function may fail if the
299 /// full directory path does not exist.
301 /// This is a convenience function for using [`File::create`] and [`write_all`]
302 /// with fewer imports.
304 /// [`write_all`]: Write::write_all
311 /// fn main() -> std::io::Result<()> {
312 /// fs::write("foo.txt", b"Lorem ipsum")?;
313 /// fs::write("bar.txt", "dolor sit")?;
317 #[stable(feature = "fs_read_write_bytes", since = "1.26.0")]
318 pub fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result<()> {
319 fn inner(path: &Path, contents: &[u8]) -> io::Result<()> {
320 File::create(path)?.write_all(contents)
322 inner(path.as_ref(), contents.as_ref())
326 /// Attempts to open a file in read-only mode.
328 /// See the [`OpenOptions::open`] method for more details.
332 /// This function will return an error if `path` does not already exist.
333 /// Other errors may also be returned according to [`OpenOptions::open`].
338 /// use std::fs::File;
340 /// fn main() -> std::io::Result<()> {
341 /// let mut f = File::open("foo.txt")?;
345 #[stable(feature = "rust1", since = "1.0.0")]
346 pub fn open<P: AsRef<Path>>(path: P) -> io::Result<File> {
347 OpenOptions::new().read(true).open(path.as_ref())
350 /// Opens a file in write-only mode.
352 /// This function will create a file if it does not exist,
353 /// and will truncate it if it does.
355 /// Depending on the platform, this function may fail if the
356 /// full directory path does not exist.
358 /// See the [`OpenOptions::open`] function for more details.
363 /// use std::fs::File;
365 /// fn main() -> std::io::Result<()> {
366 /// let mut f = File::create("foo.txt")?;
370 #[stable(feature = "rust1", since = "1.0.0")]
371 pub fn create<P: AsRef<Path>>(path: P) -> io::Result<File> {
372 OpenOptions::new().write(true).create(true).truncate(true).open(path.as_ref())
375 /// Returns a new OpenOptions object.
377 /// This function returns a new OpenOptions object that you can use to
378 /// open or create a file with specific options if `open()` or `create()`
379 /// are not appropriate.
381 /// It is equivalent to `OpenOptions::new()`, but allows you to write more
382 /// readable code. Instead of
383 /// `OpenOptions::new().append(true).open("example.log")`,
384 /// you can write `File::options().append(true).open("example.log")`. This
385 /// also avoids the need to import `OpenOptions`.
387 /// See the [`OpenOptions::new`] function for more details.
392 /// use std::fs::File;
394 /// fn main() -> std::io::Result<()> {
395 /// let mut f = File::options().append(true).open("example.log")?;
400 #[stable(feature = "with_options", since = "1.58.0")]
401 pub fn options() -> OpenOptions {
405 /// Attempts to sync all OS-internal metadata to disk.
407 /// This function will attempt to ensure that all in-memory data reaches the
408 /// filesystem before returning.
410 /// This can be used to handle errors that would otherwise only be caught
411 /// when the `File` is closed. Dropping a file will ignore errors in
412 /// synchronizing this in-memory data.
417 /// use std::fs::File;
418 /// use std::io::prelude::*;
420 /// fn main() -> std::io::Result<()> {
421 /// let mut f = File::create("foo.txt")?;
422 /// f.write_all(b"Hello, world!")?;
428 #[stable(feature = "rust1", since = "1.0.0")]
429 pub fn sync_all(&self) -> io::Result<()> {
433 /// This function is similar to [`sync_all`], except that it might not
434 /// synchronize file metadata to the filesystem.
436 /// This is intended for use cases that must synchronize content, but don't
437 /// need the metadata on disk. The goal of this method is to reduce disk
440 /// Note that some platforms may simply implement this in terms of
443 /// [`sync_all`]: File::sync_all
448 /// use std::fs::File;
449 /// use std::io::prelude::*;
451 /// fn main() -> std::io::Result<()> {
452 /// let mut f = File::create("foo.txt")?;
453 /// f.write_all(b"Hello, world!")?;
459 #[stable(feature = "rust1", since = "1.0.0")]
460 pub fn sync_data(&self) -> io::Result<()> {
461 self.inner.datasync()
464 /// Truncates or extends the underlying file, updating the size of
465 /// this file to become `size`.
467 /// If the `size` is less than the current file's size, then the file will
468 /// be shrunk. If it is greater than the current file's size, then the file
469 /// will be extended to `size` and have all of the intermediate data filled
472 /// The file's cursor isn't changed. In particular, if the cursor was at the
473 /// end and the file is shrunk using this operation, the cursor will now be
478 /// This function will return an error if the file is not opened for writing.
479 /// Also, std::io::ErrorKind::InvalidInput will be returned if the desired
480 /// length would cause an overflow due to the implementation specifics.
485 /// use std::fs::File;
487 /// fn main() -> std::io::Result<()> {
488 /// let mut f = File::create("foo.txt")?;
494 /// Note that this method alters the content of the underlying file, even
495 /// though it takes `&self` rather than `&mut self`.
496 #[stable(feature = "rust1", since = "1.0.0")]
497 pub fn set_len(&self, size: u64) -> io::Result<()> {
498 self.inner.truncate(size)
501 /// Queries metadata about the underlying file.
506 /// use std::fs::File;
508 /// fn main() -> std::io::Result<()> {
509 /// let mut f = File::open("foo.txt")?;
510 /// let metadata = f.metadata()?;
514 #[stable(feature = "rust1", since = "1.0.0")]
515 pub fn metadata(&self) -> io::Result<Metadata> {
516 self.inner.file_attr().map(Metadata)
519 /// Creates a new `File` instance that shares the same underlying file handle
520 /// as the existing `File` instance. Reads, writes, and seeks will affect
521 /// both `File` instances simultaneously.
525 /// Creates two handles for a file named `foo.txt`:
528 /// use std::fs::File;
530 /// fn main() -> std::io::Result<()> {
531 /// let mut file = File::open("foo.txt")?;
532 /// let file_copy = file.try_clone()?;
537 /// Assuming there’s a file named `foo.txt` with contents `abcdef\n`, create
538 /// two handles, seek one of them, and read the remaining bytes from the
542 /// use std::fs::File;
543 /// use std::io::SeekFrom;
544 /// use std::io::prelude::*;
546 /// fn main() -> std::io::Result<()> {
547 /// let mut file = File::open("foo.txt")?;
548 /// let mut file_copy = file.try_clone()?;
550 /// file.seek(SeekFrom::Start(3))?;
552 /// let mut contents = vec![];
553 /// file_copy.read_to_end(&mut contents)?;
554 /// assert_eq!(contents, b"def\n");
558 #[stable(feature = "file_try_clone", since = "1.9.0")]
559 pub fn try_clone(&self) -> io::Result<File> {
560 Ok(File { inner: self.inner.duplicate()? })
563 /// Changes the permissions on the underlying file.
565 /// # Platform-specific behavior
567 /// This function currently corresponds to the `fchmod` function on Unix and
568 /// the `SetFileInformationByHandle` function on Windows. Note that, this
569 /// [may change in the future][changes].
571 /// [changes]: io#platform-specific-behavior
575 /// This function will return an error if the user lacks permission change
576 /// attributes on the underlying file. It may also return an error in other
577 /// os-specific unspecified cases.
582 /// fn main() -> std::io::Result<()> {
583 /// use std::fs::File;
585 /// let file = File::open("foo.txt")?;
586 /// let mut perms = file.metadata()?.permissions();
587 /// perms.set_readonly(true);
588 /// file.set_permissions(perms)?;
593 /// Note that this method alters the permissions of the underlying file,
594 /// even though it takes `&self` rather than `&mut self`.
595 #[stable(feature = "set_permissions_atomic", since = "1.16.0")]
596 pub fn set_permissions(&self, perm: Permissions) -> io::Result<()> {
597 self.inner.set_permissions(perm.0)
601 // In addition to the `impl`s here, `File` also has `impl`s for
602 // `AsFd`/`From<OwnedFd>`/`Into<OwnedFd>` and
603 // `AsRawFd`/`IntoRawFd`/`FromRawFd`, on Unix and WASI, and
604 // `AsHandle`/`From<OwnedHandle>`/`Into<OwnedHandle>` and
605 // `AsRawHandle`/`IntoRawHandle`/`FromRawHandle` on Windows.
607 impl AsInner<fs_imp::File> for File {
608 fn as_inner(&self) -> &fs_imp::File {
612 impl FromInner<fs_imp::File> for File {
613 fn from_inner(f: fs_imp::File) -> File {
617 impl IntoInner<fs_imp::File> for File {
618 fn into_inner(self) -> fs_imp::File {
623 #[stable(feature = "rust1", since = "1.0.0")]
624 impl fmt::Debug for File {
625 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
630 /// Indicates how much extra capacity is needed to read the rest of the file.
631 fn buffer_capacity_required(mut file: &File) -> usize {
632 let size = file.metadata().map(|m| m.len()).unwrap_or(0);
633 let pos = file.stream_position().unwrap_or(0);
634 // Don't worry about `usize` overflow because reading will fail regardless
636 size.saturating_sub(pos) as usize
639 #[stable(feature = "rust1", since = "1.0.0")]
641 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
645 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
646 self.inner.read_vectored(bufs)
649 fn read_buf(&mut self, buf: &mut ReadBuf<'_>) -> io::Result<()> {
650 self.inner.read_buf(buf)
654 fn is_read_vectored(&self) -> bool {
655 self.inner.is_read_vectored()
658 // Reserves space in the buffer based on the file size when available.
659 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
660 buf.reserve(buffer_capacity_required(self));
661 io::default_read_to_end(self, buf)
664 // Reserves space in the buffer based on the file size when available.
665 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
666 buf.reserve(buffer_capacity_required(self));
667 io::default_read_to_string(self, buf)
670 #[stable(feature = "rust1", since = "1.0.0")]
671 impl Write for File {
672 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
673 self.inner.write(buf)
676 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
677 self.inner.write_vectored(bufs)
681 fn is_write_vectored(&self) -> bool {
682 self.inner.is_write_vectored()
685 fn flush(&mut self) -> io::Result<()> {
689 #[stable(feature = "rust1", since = "1.0.0")]
691 fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
695 #[stable(feature = "rust1", since = "1.0.0")]
696 impl Read for &File {
697 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
701 fn read_buf(&mut self, buf: &mut ReadBuf<'_>) -> io::Result<()> {
702 self.inner.read_buf(buf)
705 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
706 self.inner.read_vectored(bufs)
710 fn is_read_vectored(&self) -> bool {
711 self.inner.is_read_vectored()
714 // Reserves space in the buffer based on the file size when available.
715 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
716 buf.reserve(buffer_capacity_required(self));
717 io::default_read_to_end(self, buf)
720 // Reserves space in the buffer based on the file size when available.
721 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
722 buf.reserve(buffer_capacity_required(self));
723 io::default_read_to_string(self, buf)
726 #[stable(feature = "rust1", since = "1.0.0")]
727 impl Write for &File {
728 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
729 self.inner.write(buf)
732 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
733 self.inner.write_vectored(bufs)
737 fn is_write_vectored(&self) -> bool {
738 self.inner.is_write_vectored()
741 fn flush(&mut self) -> io::Result<()> {
745 #[stable(feature = "rust1", since = "1.0.0")]
746 impl Seek for &File {
747 fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
753 /// Creates a blank new set of options ready for configuration.
755 /// All options are initially set to `false`.
760 /// use std::fs::OpenOptions;
762 /// let mut options = OpenOptions::new();
763 /// let file = options.read(true).open("foo.txt");
765 #[stable(feature = "rust1", since = "1.0.0")]
767 pub fn new() -> Self {
768 OpenOptions(fs_imp::OpenOptions::new())
771 /// Sets the option for read access.
773 /// This option, when true, will indicate that the file should be
774 /// `read`-able if opened.
779 /// use std::fs::OpenOptions;
781 /// let file = OpenOptions::new().read(true).open("foo.txt");
783 #[stable(feature = "rust1", since = "1.0.0")]
784 pub fn read(&mut self, read: bool) -> &mut Self {
789 /// Sets the option for write access.
791 /// This option, when true, will indicate that the file should be
792 /// `write`-able if opened.
794 /// If the file already exists, any write calls on it will overwrite its
795 /// contents, without truncating it.
800 /// use std::fs::OpenOptions;
802 /// let file = OpenOptions::new().write(true).open("foo.txt");
804 #[stable(feature = "rust1", since = "1.0.0")]
805 pub fn write(&mut self, write: bool) -> &mut Self {
810 /// Sets the option for the append mode.
812 /// This option, when true, means that writes will append to a file instead
813 /// of overwriting previous contents.
814 /// Note that setting `.write(true).append(true)` has the same effect as
815 /// setting only `.append(true)`.
817 /// For most filesystems, the operating system guarantees that all writes are
818 /// atomic: no writes get mangled because another process writes at the same
821 /// One maybe obvious note when using append-mode: make sure that all data
822 /// that belongs together is written to the file in one operation. This
823 /// can be done by concatenating strings before passing them to [`write()`],
824 /// or using a buffered writer (with a buffer of adequate size),
825 /// and calling [`flush()`] when the message is complete.
827 /// If a file is opened with both read and append access, beware that after
828 /// opening, and after every write, the position for reading may be set at the
829 /// end of the file. So, before writing, save the current position (using
830 /// <code>[seek]\([SeekFrom]::[Current]\(0))</code>), and restore it before the next read.
834 /// This function doesn't create the file if it doesn't exist. Use the
835 /// [`OpenOptions::create`] method to do so.
837 /// [`write()`]: Write::write "io::Write::write"
838 /// [`flush()`]: Write::flush "io::Write::flush"
839 /// [seek]: Seek::seek "io::Seek::seek"
840 /// [Current]: SeekFrom::Current "io::SeekFrom::Current"
845 /// use std::fs::OpenOptions;
847 /// let file = OpenOptions::new().append(true).open("foo.txt");
849 #[stable(feature = "rust1", since = "1.0.0")]
850 pub fn append(&mut self, append: bool) -> &mut Self {
851 self.0.append(append);
855 /// Sets the option for truncating a previous file.
857 /// If a file is successfully opened with this option set it will truncate
858 /// the file to 0 length if it already exists.
860 /// The file must be opened with write access for truncate to work.
865 /// use std::fs::OpenOptions;
867 /// let file = OpenOptions::new().write(true).truncate(true).open("foo.txt");
869 #[stable(feature = "rust1", since = "1.0.0")]
870 pub fn truncate(&mut self, truncate: bool) -> &mut Self {
871 self.0.truncate(truncate);
875 /// Sets the option to create a new file, or open it if it already exists.
877 /// In order for the file to be created, [`OpenOptions::write`] or
878 /// [`OpenOptions::append`] access must be used.
883 /// use std::fs::OpenOptions;
885 /// let file = OpenOptions::new().write(true).create(true).open("foo.txt");
887 #[stable(feature = "rust1", since = "1.0.0")]
888 pub fn create(&mut self, create: bool) -> &mut Self {
889 self.0.create(create);
893 /// Sets the option to create a new file, failing if it already exists.
895 /// No file is allowed to exist at the target location, also no (dangling) symlink. In this
896 /// way, if the call succeeds, the file returned is guaranteed to be new.
898 /// This option is useful because it is atomic. Otherwise between checking
899 /// whether a file exists and creating a new one, the file may have been
900 /// created by another process (a TOCTOU race condition / attack).
902 /// If `.create_new(true)` is set, [`.create()`] and [`.truncate()`] are
905 /// The file must be opened with write or append access in order to create
908 /// [`.create()`]: OpenOptions::create
909 /// [`.truncate()`]: OpenOptions::truncate
914 /// use std::fs::OpenOptions;
916 /// let file = OpenOptions::new().write(true)
917 /// .create_new(true)
918 /// .open("foo.txt");
920 #[stable(feature = "expand_open_options2", since = "1.9.0")]
921 pub fn create_new(&mut self, create_new: bool) -> &mut Self {
922 self.0.create_new(create_new);
926 /// Opens a file at `path` with the options specified by `self`.
930 /// This function will return an error under a number of different
931 /// circumstances. Some of these error conditions are listed here, together
932 /// with their [`io::ErrorKind`]. The mapping to [`io::ErrorKind`]s is not
933 /// part of the compatibility contract of the function.
935 /// * [`NotFound`]: The specified file does not exist and neither `create`
936 /// or `create_new` is set.
937 /// * [`NotFound`]: One of the directory components of the file path does
939 /// * [`PermissionDenied`]: The user lacks permission to get the specified
940 /// access rights for the file.
941 /// * [`PermissionDenied`]: The user lacks permission to open one of the
942 /// directory components of the specified path.
943 /// * [`AlreadyExists`]: `create_new` was specified and the file already
945 /// * [`InvalidInput`]: Invalid combinations of open options (truncate
946 /// without write access, no access mode set, etc.).
948 /// The following errors don't match any existing [`io::ErrorKind`] at the moment:
949 /// * One of the directory components of the specified file path
950 /// was not, in fact, a directory.
951 /// * Filesystem-level errors: full disk, write permission
952 /// requested on a read-only file system, exceeded disk quota, too many
953 /// open files, too long filename, too many symbolic links in the
954 /// specified path (Unix-like systems only), etc.
959 /// use std::fs::OpenOptions;
961 /// let file = OpenOptions::new().read(true).open("foo.txt");
964 /// [`AlreadyExists`]: io::ErrorKind::AlreadyExists
965 /// [`InvalidInput`]: io::ErrorKind::InvalidInput
966 /// [`NotFound`]: io::ErrorKind::NotFound
967 /// [`PermissionDenied`]: io::ErrorKind::PermissionDenied
968 #[stable(feature = "rust1", since = "1.0.0")]
969 pub fn open<P: AsRef<Path>>(&self, path: P) -> io::Result<File> {
970 self._open(path.as_ref())
973 fn _open(&self, path: &Path) -> io::Result<File> {
974 fs_imp::File::open(path, &self.0).map(|inner| File { inner })
978 impl AsInner<fs_imp::OpenOptions> for OpenOptions {
979 fn as_inner(&self) -> &fs_imp::OpenOptions {
984 impl AsInnerMut<fs_imp::OpenOptions> for OpenOptions {
985 fn as_inner_mut(&mut self) -> &mut fs_imp::OpenOptions {
991 /// Returns the file type for this metadata.
996 /// fn main() -> std::io::Result<()> {
999 /// let metadata = fs::metadata("foo.txt")?;
1001 /// println!("{:?}", metadata.file_type());
1006 #[stable(feature = "file_type", since = "1.1.0")]
1007 pub fn file_type(&self) -> FileType {
1008 FileType(self.0.file_type())
1011 /// Returns `true` if this metadata is for a directory. The
1012 /// result is mutually exclusive to the result of
1013 /// [`Metadata::is_file`], and will be false for symlink metadata
1014 /// obtained from [`symlink_metadata`].
1019 /// fn main() -> std::io::Result<()> {
1022 /// let metadata = fs::metadata("foo.txt")?;
1024 /// assert!(!metadata.is_dir());
1029 #[stable(feature = "rust1", since = "1.0.0")]
1030 pub fn is_dir(&self) -> bool {
1031 self.file_type().is_dir()
1034 /// Returns `true` if this metadata is for a regular file. The
1035 /// result is mutually exclusive to the result of
1036 /// [`Metadata::is_dir`], and will be false for symlink metadata
1037 /// obtained from [`symlink_metadata`].
1039 /// When the goal is simply to read from (or write to) the source, the most
1040 /// reliable way to test the source can be read (or written to) is to open
1041 /// it. Only using `is_file` can break workflows like `diff <( prog_a )` on
1042 /// a Unix-like system for example. See [`File::open`] or
1043 /// [`OpenOptions::open`] for more information.
1050 /// fn main() -> std::io::Result<()> {
1051 /// let metadata = fs::metadata("foo.txt")?;
1053 /// assert!(metadata.is_file());
1058 #[stable(feature = "rust1", since = "1.0.0")]
1059 pub fn is_file(&self) -> bool {
1060 self.file_type().is_file()
1063 /// Returns `true` if this metadata is for a symbolic link.
1067 #[cfg_attr(unix, doc = "```no_run")]
1068 #[cfg_attr(not(unix), doc = "```ignore")]
1070 /// use std::path::Path;
1071 /// use std::os::unix::fs::symlink;
1073 /// fn main() -> std::io::Result<()> {
1074 /// let link_path = Path::new("link");
1075 /// symlink("/origin_does_not_exist/", link_path)?;
1077 /// let metadata = fs::symlink_metadata(link_path)?;
1079 /// assert!(metadata.is_symlink());
1084 #[stable(feature = "is_symlink", since = "1.58.0")]
1085 pub fn is_symlink(&self) -> bool {
1086 self.file_type().is_symlink()
1089 /// Returns the size of the file, in bytes, this metadata is for.
1096 /// fn main() -> std::io::Result<()> {
1097 /// let metadata = fs::metadata("foo.txt")?;
1099 /// assert_eq!(0, metadata.len());
1104 #[stable(feature = "rust1", since = "1.0.0")]
1105 pub fn len(&self) -> u64 {
1109 /// Returns the permissions of the file this metadata is for.
1116 /// fn main() -> std::io::Result<()> {
1117 /// let metadata = fs::metadata("foo.txt")?;
1119 /// assert!(!metadata.permissions().readonly());
1124 #[stable(feature = "rust1", since = "1.0.0")]
1125 pub fn permissions(&self) -> Permissions {
1126 Permissions(self.0.perm())
1129 /// Returns the last modification time listed in this metadata.
1131 /// The returned value corresponds to the `mtime` field of `stat` on Unix
1132 /// platforms and the `ftLastWriteTime` field on Windows platforms.
1136 /// This field might not be available on all platforms, and will return an
1137 /// `Err` on platforms where it is not available.
1144 /// fn main() -> std::io::Result<()> {
1145 /// let metadata = fs::metadata("foo.txt")?;
1147 /// if let Ok(time) = metadata.modified() {
1148 /// println!("{time:?}");
1150 /// println!("Not supported on this platform");
1155 #[stable(feature = "fs_time", since = "1.10.0")]
1156 pub fn modified(&self) -> io::Result<SystemTime> {
1157 self.0.modified().map(FromInner::from_inner)
1160 /// Returns the last access time of this metadata.
1162 /// The returned value corresponds to the `atime` field of `stat` on Unix
1163 /// platforms and the `ftLastAccessTime` field on Windows platforms.
1165 /// Note that not all platforms will keep this field update in a file's
1166 /// metadata, for example Windows has an option to disable updating this
1167 /// time when files are accessed and Linux similarly has `noatime`.
1171 /// This field might not be available on all platforms, and will return an
1172 /// `Err` on platforms where it is not available.
1179 /// fn main() -> std::io::Result<()> {
1180 /// let metadata = fs::metadata("foo.txt")?;
1182 /// if let Ok(time) = metadata.accessed() {
1183 /// println!("{time:?}");
1185 /// println!("Not supported on this platform");
1190 #[stable(feature = "fs_time", since = "1.10.0")]
1191 pub fn accessed(&self) -> io::Result<SystemTime> {
1192 self.0.accessed().map(FromInner::from_inner)
1195 /// Returns the creation time listed in this metadata.
1197 /// The returned value corresponds to the `btime` field of `statx` on
1198 /// Linux kernel starting from to 4.11, the `birthtime` field of `stat` on other
1199 /// Unix platforms, and the `ftCreationTime` field on Windows platforms.
1203 /// This field might not be available on all platforms, and will return an
1204 /// `Err` on platforms or filesystems where it is not available.
1211 /// fn main() -> std::io::Result<()> {
1212 /// let metadata = fs::metadata("foo.txt")?;
1214 /// if let Ok(time) = metadata.created() {
1215 /// println!("{time:?}");
1217 /// println!("Not supported on this platform or filesystem");
1222 #[stable(feature = "fs_time", since = "1.10.0")]
1223 pub fn created(&self) -> io::Result<SystemTime> {
1224 self.0.created().map(FromInner::from_inner)
1228 #[stable(feature = "std_debug", since = "1.16.0")]
1229 impl fmt::Debug for Metadata {
1230 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1231 f.debug_struct("Metadata")
1232 .field("file_type", &self.file_type())
1233 .field("is_dir", &self.is_dir())
1234 .field("is_file", &self.is_file())
1235 .field("permissions", &self.permissions())
1236 .field("modified", &self.modified())
1237 .field("accessed", &self.accessed())
1238 .field("created", &self.created())
1239 .finish_non_exhaustive()
1243 impl AsInner<fs_imp::FileAttr> for Metadata {
1244 fn as_inner(&self) -> &fs_imp::FileAttr {
1249 impl FromInner<fs_imp::FileAttr> for Metadata {
1250 fn from_inner(attr: fs_imp::FileAttr) -> Metadata {
1256 /// Returns `true` if these permissions describe a readonly (unwritable) file.
1261 /// use std::fs::File;
1263 /// fn main() -> std::io::Result<()> {
1264 /// let mut f = File::create("foo.txt")?;
1265 /// let metadata = f.metadata()?;
1267 /// assert_eq!(false, metadata.permissions().readonly());
1271 #[must_use = "call `set_readonly` to modify the readonly flag"]
1272 #[stable(feature = "rust1", since = "1.0.0")]
1273 pub fn readonly(&self) -> bool {
1277 /// Modifies the readonly flag for this set of permissions. If the
1278 /// `readonly` argument is `true`, using the resulting `Permission` will
1279 /// update file permissions to forbid writing. Conversely, if it's `false`,
1280 /// using the resulting `Permission` will update file permissions to allow
1283 /// This operation does **not** modify the filesystem. To modify the
1284 /// filesystem use the [`set_permissions`] function.
1289 /// use std::fs::File;
1291 /// fn main() -> std::io::Result<()> {
1292 /// let f = File::create("foo.txt")?;
1293 /// let metadata = f.metadata()?;
1294 /// let mut permissions = metadata.permissions();
1296 /// permissions.set_readonly(true);
1298 /// // filesystem doesn't change
1299 /// assert_eq!(false, metadata.permissions().readonly());
1301 /// // just this particular `permissions`.
1302 /// assert_eq!(true, permissions.readonly());
1306 #[stable(feature = "rust1", since = "1.0.0")]
1307 pub fn set_readonly(&mut self, readonly: bool) {
1308 self.0.set_readonly(readonly)
1313 /// Tests whether this file type represents a directory. The
1314 /// result is mutually exclusive to the results of
1315 /// [`is_file`] and [`is_symlink`]; only zero or one of these
1318 /// [`is_file`]: FileType::is_file
1319 /// [`is_symlink`]: FileType::is_symlink
1324 /// fn main() -> std::io::Result<()> {
1327 /// let metadata = fs::metadata("foo.txt")?;
1328 /// let file_type = metadata.file_type();
1330 /// assert_eq!(file_type.is_dir(), false);
1335 #[stable(feature = "file_type", since = "1.1.0")]
1336 pub fn is_dir(&self) -> bool {
1340 /// Tests whether this file type represents a regular file.
1341 /// The result is mutually exclusive to the results of
1342 /// [`is_dir`] and [`is_symlink`]; only zero or one of these
1345 /// When the goal is simply to read from (or write to) the source, the most
1346 /// reliable way to test the source can be read (or written to) is to open
1347 /// it. Only using `is_file` can break workflows like `diff <( prog_a )` on
1348 /// a Unix-like system for example. See [`File::open`] or
1349 /// [`OpenOptions::open`] for more information.
1351 /// [`is_dir`]: FileType::is_dir
1352 /// [`is_symlink`]: FileType::is_symlink
1357 /// fn main() -> std::io::Result<()> {
1360 /// let metadata = fs::metadata("foo.txt")?;
1361 /// let file_type = metadata.file_type();
1363 /// assert_eq!(file_type.is_file(), true);
1368 #[stable(feature = "file_type", since = "1.1.0")]
1369 pub fn is_file(&self) -> bool {
1373 /// Tests whether this file type represents a symbolic link.
1374 /// The result is mutually exclusive to the results of
1375 /// [`is_dir`] and [`is_file`]; only zero or one of these
1378 /// The underlying [`Metadata`] struct needs to be retrieved
1379 /// with the [`fs::symlink_metadata`] function and not the
1380 /// [`fs::metadata`] function. The [`fs::metadata`] function
1381 /// follows symbolic links, so [`is_symlink`] would always
1382 /// return `false` for the target file.
1384 /// [`fs::metadata`]: metadata
1385 /// [`fs::symlink_metadata`]: symlink_metadata
1386 /// [`is_dir`]: FileType::is_dir
1387 /// [`is_file`]: FileType::is_file
1388 /// [`is_symlink`]: FileType::is_symlink
1395 /// fn main() -> std::io::Result<()> {
1396 /// let metadata = fs::symlink_metadata("foo.txt")?;
1397 /// let file_type = metadata.file_type();
1399 /// assert_eq!(file_type.is_symlink(), false);
1404 #[stable(feature = "file_type", since = "1.1.0")]
1405 pub fn is_symlink(&self) -> bool {
1410 impl AsInner<fs_imp::FileType> for FileType {
1411 fn as_inner(&self) -> &fs_imp::FileType {
1416 impl FromInner<fs_imp::FilePermissions> for Permissions {
1417 fn from_inner(f: fs_imp::FilePermissions) -> Permissions {
1422 impl AsInner<fs_imp::FilePermissions> for Permissions {
1423 fn as_inner(&self) -> &fs_imp::FilePermissions {
1428 #[stable(feature = "rust1", since = "1.0.0")]
1429 impl Iterator for ReadDir {
1430 type Item = io::Result<DirEntry>;
1432 fn next(&mut self) -> Option<io::Result<DirEntry>> {
1433 self.0.next().map(|entry| entry.map(DirEntry))
1438 /// Returns the full path to the file that this entry represents.
1440 /// The full path is created by joining the original path to `read_dir`
1441 /// with the filename of this entry.
1448 /// fn main() -> std::io::Result<()> {
1449 /// for entry in fs::read_dir(".")? {
1450 /// let dir = entry?;
1451 /// println!("{:?}", dir.path());
1457 /// This prints output like:
1460 /// "./whatever.txt"
1462 /// "./hello_world.rs"
1465 /// The exact text, of course, depends on what files you have in `.`.
1467 #[stable(feature = "rust1", since = "1.0.0")]
1468 pub fn path(&self) -> PathBuf {
1472 /// Returns the metadata for the file that this entry points at.
1474 /// This function will not traverse symlinks if this entry points at a
1475 /// symlink. To traverse symlinks use [`fs::metadata`] or [`fs::File::metadata`].
1477 /// [`fs::metadata`]: metadata
1478 /// [`fs::File::metadata`]: File::metadata
1480 /// # Platform-specific behavior
1482 /// On Windows this function is cheap to call (no extra system calls
1483 /// needed), but on Unix platforms this function is the equivalent of
1484 /// calling `symlink_metadata` on the path.
1491 /// if let Ok(entries) = fs::read_dir(".") {
1492 /// for entry in entries {
1493 /// if let Ok(entry) = entry {
1494 /// // Here, `entry` is a `DirEntry`.
1495 /// if let Ok(metadata) = entry.metadata() {
1496 /// // Now let's show our entry's permissions!
1497 /// println!("{:?}: {:?}", entry.path(), metadata.permissions());
1499 /// println!("Couldn't get metadata for {:?}", entry.path());
1505 #[stable(feature = "dir_entry_ext", since = "1.1.0")]
1506 pub fn metadata(&self) -> io::Result<Metadata> {
1507 self.0.metadata().map(Metadata)
1510 /// Returns the file type for the file that this entry points at.
1512 /// This function will not traverse symlinks if this entry points at a
1515 /// # Platform-specific behavior
1517 /// On Windows and most Unix platforms this function is free (no extra
1518 /// system calls needed), but some Unix platforms may require the equivalent
1519 /// call to `symlink_metadata` to learn about the target file type.
1526 /// if let Ok(entries) = fs::read_dir(".") {
1527 /// for entry in entries {
1528 /// if let Ok(entry) = entry {
1529 /// // Here, `entry` is a `DirEntry`.
1530 /// if let Ok(file_type) = entry.file_type() {
1531 /// // Now let's show our entry's file type!
1532 /// println!("{:?}: {:?}", entry.path(), file_type);
1534 /// println!("Couldn't get file type for {:?}", entry.path());
1540 #[stable(feature = "dir_entry_ext", since = "1.1.0")]
1541 pub fn file_type(&self) -> io::Result<FileType> {
1542 self.0.file_type().map(FileType)
1545 /// Returns the bare file name of this directory entry without any other
1546 /// leading path component.
1553 /// if let Ok(entries) = fs::read_dir(".") {
1554 /// for entry in entries {
1555 /// if let Ok(entry) = entry {
1556 /// // Here, `entry` is a `DirEntry`.
1557 /// println!("{:?}", entry.file_name());
1563 #[stable(feature = "dir_entry_ext", since = "1.1.0")]
1564 pub fn file_name(&self) -> OsString {
1569 #[stable(feature = "dir_entry_debug", since = "1.13.0")]
1570 impl fmt::Debug for DirEntry {
1571 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1572 f.debug_tuple("DirEntry").field(&self.path()).finish()
1576 impl AsInner<fs_imp::DirEntry> for DirEntry {
1577 fn as_inner(&self) -> &fs_imp::DirEntry {
1582 /// Removes a file from the filesystem.
1584 /// Note that there is no
1585 /// guarantee that the file is immediately deleted (e.g., depending on
1586 /// platform, other open file descriptors may prevent immediate removal).
1588 /// # Platform-specific behavior
1590 /// This function currently corresponds to the `unlink` function on Unix
1591 /// and the `DeleteFile` function on Windows.
1592 /// Note that, this [may change in the future][changes].
1594 /// [changes]: io#platform-specific-behavior
1598 /// This function will return an error in the following situations, but is not
1599 /// limited to just these cases:
1601 /// * `path` points to a directory.
1602 /// * The file doesn't exist.
1603 /// * The user lacks permissions to remove the file.
1610 /// fn main() -> std::io::Result<()> {
1611 /// fs::remove_file("a.txt")?;
1615 #[stable(feature = "rust1", since = "1.0.0")]
1616 pub fn remove_file<P: AsRef<Path>>(path: P) -> io::Result<()> {
1617 fs_imp::unlink(path.as_ref())
1620 /// Given a path, query the file system to get information about a file,
1623 /// This function will traverse symbolic links to query information about the
1624 /// destination file.
1626 /// # Platform-specific behavior
1628 /// This function currently corresponds to the `stat` function on Unix
1629 /// and the `GetFileInformationByHandle` function on Windows.
1630 /// Note that, this [may change in the future][changes].
1632 /// [changes]: io#platform-specific-behavior
1636 /// This function will return an error in the following situations, but is not
1637 /// limited to just these cases:
1639 /// * The user lacks permissions to perform `metadata` call on `path`.
1640 /// * `path` does not exist.
1647 /// fn main() -> std::io::Result<()> {
1648 /// let attr = fs::metadata("/some/file/path.txt")?;
1649 /// // inspect attr ...
1653 #[stable(feature = "rust1", since = "1.0.0")]
1654 pub fn metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
1655 fs_imp::stat(path.as_ref()).map(Metadata)
1658 /// Query the metadata about a file without following symlinks.
1660 /// # Platform-specific behavior
1662 /// This function currently corresponds to the `lstat` function on Unix
1663 /// and the `GetFileInformationByHandle` function on Windows.
1664 /// Note that, this [may change in the future][changes].
1666 /// [changes]: io#platform-specific-behavior
1670 /// This function will return an error in the following situations, but is not
1671 /// limited to just these cases:
1673 /// * The user lacks permissions to perform `metadata` call on `path`.
1674 /// * `path` does not exist.
1681 /// fn main() -> std::io::Result<()> {
1682 /// let attr = fs::symlink_metadata("/some/file/path.txt")?;
1683 /// // inspect attr ...
1687 #[stable(feature = "symlink_metadata", since = "1.1.0")]
1688 pub fn symlink_metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
1689 fs_imp::lstat(path.as_ref()).map(Metadata)
1692 /// Rename a file or directory to a new name, replacing the original file if
1693 /// `to` already exists.
1695 /// This will not work if the new name is on a different mount point.
1697 /// # Platform-specific behavior
1699 /// This function currently corresponds to the `rename` function on Unix
1700 /// and the `MoveFileEx` function with the `MOVEFILE_REPLACE_EXISTING` flag on Windows.
1702 /// Because of this, the behavior when both `from` and `to` exist differs. On
1703 /// Unix, if `from` is a directory, `to` must also be an (empty) directory. If
1704 /// `from` is not a directory, `to` must also be not a directory. In contrast,
1705 /// on Windows, `from` can be anything, but `to` must *not* be a directory.
1707 /// Note that, this [may change in the future][changes].
1709 /// [changes]: io#platform-specific-behavior
1713 /// This function will return an error in the following situations, but is not
1714 /// limited to just these cases:
1716 /// * `from` does not exist.
1717 /// * The user lacks permissions to view contents.
1718 /// * `from` and `to` are on separate filesystems.
1725 /// fn main() -> std::io::Result<()> {
1726 /// fs::rename("a.txt", "b.txt")?; // Rename a.txt to b.txt
1730 #[stable(feature = "rust1", since = "1.0.0")]
1731 pub fn rename<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()> {
1732 fs_imp::rename(from.as_ref(), to.as_ref())
1735 /// Copies the contents of one file to another. This function will also
1736 /// copy the permission bits of the original file to the destination file.
1738 /// This function will **overwrite** the contents of `to`.
1740 /// Note that if `from` and `to` both point to the same file, then the file
1741 /// will likely get truncated by this operation.
1743 /// On success, the total number of bytes copied is returned and it is equal to
1744 /// the length of the `to` file as reported by `metadata`.
1746 /// If you’re wanting to copy the contents of one file to another and you’re
1747 /// working with [`File`]s, see the [`io::copy()`] function.
1749 /// # Platform-specific behavior
1751 /// This function currently corresponds to the `open` function in Unix
1752 /// with `O_RDONLY` for `from` and `O_WRONLY`, `O_CREAT`, and `O_TRUNC` for `to`.
1753 /// `O_CLOEXEC` is set for returned file descriptors.
1755 /// On Linux (including Android), this function attempts to use `copy_file_range(2)`,
1756 /// and falls back to reading and writing if that is not possible.
1758 /// On Windows, this function currently corresponds to `CopyFileEx`. Alternate
1759 /// NTFS streams are copied but only the size of the main stream is returned by
1762 /// On MacOS, this function corresponds to `fclonefileat` and `fcopyfile`.
1764 /// Note that platform-specific behavior [may change in the future][changes].
1766 /// [changes]: io#platform-specific-behavior
1770 /// This function will return an error in the following situations, but is not
1771 /// limited to just these cases:
1773 /// * `from` is neither a regular file nor a symlink to a regular file.
1774 /// * `from` does not exist.
1775 /// * The current process does not have the permission rights to read
1776 /// `from` or write `to`.
1783 /// fn main() -> std::io::Result<()> {
1784 /// fs::copy("foo.txt", "bar.txt")?; // Copy foo.txt to bar.txt
1788 #[stable(feature = "rust1", since = "1.0.0")]
1789 pub fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<u64> {
1790 fs_imp::copy(from.as_ref(), to.as_ref())
1793 /// Creates a new hard link on the filesystem.
1795 /// The `link` path will be a link pointing to the `original` path. Note that
1796 /// systems often require these two paths to both be located on the same
1799 /// If `original` names a symbolic link, it is platform-specific whether the
1800 /// symbolic link is followed. On platforms where it's possible to not follow
1801 /// it, it is not followed, and the created hard link points to the symbolic
1804 /// # Platform-specific behavior
1806 /// This function currently corresponds the `CreateHardLink` function on Windows.
1807 /// On most Unix systems, it corresponds to the `linkat` function with no flags.
1808 /// On Android, VxWorks, and Redox, it instead corresponds to the `link` function.
1809 /// On MacOS, it uses the `linkat` function if it is available, but on very old
1810 /// systems where `linkat` is not available, `link` is selected at runtime instead.
1811 /// Note that, this [may change in the future][changes].
1813 /// [changes]: io#platform-specific-behavior
1817 /// This function will return an error in the following situations, but is not
1818 /// limited to just these cases:
1820 /// * The `original` path is not a file or doesn't exist.
1827 /// fn main() -> std::io::Result<()> {
1828 /// fs::hard_link("a.txt", "b.txt")?; // Hard link a.txt to b.txt
1832 #[stable(feature = "rust1", since = "1.0.0")]
1833 pub fn hard_link<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Result<()> {
1834 fs_imp::link(original.as_ref(), link.as_ref())
1837 /// Creates a new symbolic link on the filesystem.
1839 /// The `link` path will be a symbolic link pointing to the `original` path.
1840 /// On Windows, this will be a file symlink, not a directory symlink;
1841 /// for this reason, the platform-specific [`std::os::unix::fs::symlink`]
1842 /// and [`std::os::windows::fs::symlink_file`] or [`symlink_dir`] should be
1843 /// used instead to make the intent explicit.
1845 /// [`std::os::unix::fs::symlink`]: crate::os::unix::fs::symlink
1846 /// [`std::os::windows::fs::symlink_file`]: crate::os::windows::fs::symlink_file
1847 /// [`symlink_dir`]: crate::os::windows::fs::symlink_dir
1854 /// fn main() -> std::io::Result<()> {
1855 /// fs::soft_link("a.txt", "b.txt")?;
1859 #[stable(feature = "rust1", since = "1.0.0")]
1862 note = "replaced with std::os::unix::fs::symlink and \
1863 std::os::windows::fs::{symlink_file, symlink_dir}"
1865 pub fn soft_link<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Result<()> {
1866 fs_imp::symlink(original.as_ref(), link.as_ref())
1869 /// Reads a symbolic link, returning the file that the link points to.
1871 /// # Platform-specific behavior
1873 /// This function currently corresponds to the `readlink` function on Unix
1874 /// and the `CreateFile` function with `FILE_FLAG_OPEN_REPARSE_POINT` and
1875 /// `FILE_FLAG_BACKUP_SEMANTICS` flags on Windows.
1876 /// Note that, this [may change in the future][changes].
1878 /// [changes]: io#platform-specific-behavior
1882 /// This function will return an error in the following situations, but is not
1883 /// limited to just these cases:
1885 /// * `path` is not a symbolic link.
1886 /// * `path` does not exist.
1893 /// fn main() -> std::io::Result<()> {
1894 /// let path = fs::read_link("a.txt")?;
1898 #[stable(feature = "rust1", since = "1.0.0")]
1899 pub fn read_link<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
1900 fs_imp::readlink(path.as_ref())
1903 /// Returns the canonical, absolute form of a path with all intermediate
1904 /// components normalized and symbolic links resolved.
1906 /// # Platform-specific behavior
1908 /// This function currently corresponds to the `realpath` function on Unix
1909 /// and the `CreateFile` and `GetFinalPathNameByHandle` functions on Windows.
1910 /// Note that, this [may change in the future][changes].
1912 /// On Windows, this converts the path to use [extended length path][path]
1913 /// syntax, which allows your program to use longer path names, but means you
1914 /// can only join backslash-delimited paths to it, and it may be incompatible
1915 /// with other applications (if passed to the application on the command-line,
1916 /// or written to a file another application may read).
1918 /// [changes]: io#platform-specific-behavior
1919 /// [path]: https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file
1923 /// This function will return an error in the following situations, but is not
1924 /// limited to just these cases:
1926 /// * `path` does not exist.
1927 /// * A non-final component in path is not a directory.
1934 /// fn main() -> std::io::Result<()> {
1935 /// let path = fs::canonicalize("../a/../foo.txt")?;
1939 #[doc(alias = "realpath")]
1940 #[doc(alias = "GetFinalPathNameByHandle")]
1941 #[stable(feature = "fs_canonicalize", since = "1.5.0")]
1942 pub fn canonicalize<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
1943 fs_imp::canonicalize(path.as_ref())
1946 /// Creates a new, empty directory at the provided path
1948 /// # Platform-specific behavior
1950 /// This function currently corresponds to the `mkdir` function on Unix
1951 /// and the `CreateDirectory` function on Windows.
1952 /// Note that, this [may change in the future][changes].
1954 /// [changes]: io#platform-specific-behavior
1956 /// **NOTE**: If a parent of the given path doesn't exist, this function will
1957 /// return an error. To create a directory and all its missing parents at the
1958 /// same time, use the [`create_dir_all`] function.
1962 /// This function will return an error in the following situations, but is not
1963 /// limited to just these cases:
1965 /// * User lacks permissions to create directory at `path`.
1966 /// * A parent of the given path doesn't exist. (To create a directory and all
1967 /// its missing parents at the same time, use the [`create_dir_all`]
1969 /// * `path` already exists.
1976 /// fn main() -> std::io::Result<()> {
1977 /// fs::create_dir("/some/dir")?;
1981 #[doc(alias = "mkdir")]
1982 #[stable(feature = "rust1", since = "1.0.0")]
1983 pub fn create_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
1984 DirBuilder::new().create(path.as_ref())
1987 /// Recursively create a directory and all of its parent components if they
1990 /// # Platform-specific behavior
1992 /// This function currently corresponds to the `mkdir` function on Unix
1993 /// and the `CreateDirectory` function on Windows.
1994 /// Note that, this [may change in the future][changes].
1996 /// [changes]: io#platform-specific-behavior
2000 /// This function will return an error in the following situations, but is not
2001 /// limited to just these cases:
2003 /// * If any directory in the path specified by `path`
2004 /// does not already exist and it could not be created otherwise. The specific
2005 /// error conditions for when a directory is being created (after it is
2006 /// determined to not exist) are outlined by [`fs::create_dir`].
2008 /// Notable exception is made for situations where any of the directories
2009 /// specified in the `path` could not be created as it was being created concurrently.
2010 /// Such cases are considered to be successful. That is, calling `create_dir_all`
2011 /// concurrently from multiple threads or processes is guaranteed not to fail
2012 /// due to a race condition with itself.
2014 /// [`fs::create_dir`]: create_dir
2021 /// fn main() -> std::io::Result<()> {
2022 /// fs::create_dir_all("/some/dir")?;
2026 #[stable(feature = "rust1", since = "1.0.0")]
2027 pub fn create_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
2028 DirBuilder::new().recursive(true).create(path.as_ref())
2031 /// Removes an empty directory.
2033 /// # Platform-specific behavior
2035 /// This function currently corresponds to the `rmdir` function on Unix
2036 /// and the `RemoveDirectory` function on Windows.
2037 /// Note that, this [may change in the future][changes].
2039 /// [changes]: io#platform-specific-behavior
2043 /// This function will return an error in the following situations, but is not
2044 /// limited to just these cases:
2046 /// * `path` doesn't exist.
2047 /// * `path` isn't a directory.
2048 /// * The user lacks permissions to remove the directory at the provided `path`.
2049 /// * The directory isn't empty.
2056 /// fn main() -> std::io::Result<()> {
2057 /// fs::remove_dir("/some/dir")?;
2061 #[doc(alias = "rmdir")]
2062 #[stable(feature = "rust1", since = "1.0.0")]
2063 pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
2064 fs_imp::rmdir(path.as_ref())
2067 /// Removes a directory at this path, after removing all its contents. Use
2070 /// This function does **not** follow symbolic links and it will simply remove the
2071 /// symbolic link itself.
2073 /// # Platform-specific behavior
2075 /// This function currently corresponds to `openat`, `fdopendir`, `unlinkat` and `lstat` functions
2076 /// on Unix (except for macOS before version 10.10 and REDOX) and the `CreateFileW`,
2077 /// `GetFileInformationByHandleEx`, `SetFileInformationByHandle`, and `NtCreateFile` functions on
2078 /// Windows. Note that, this [may change in the future][changes].
2080 /// [changes]: io#platform-specific-behavior
2082 /// On macOS before version 10.10 and REDOX, as well as when running in Miri for any target, this
2083 /// function is not protected against time-of-check to time-of-use (TOCTOU) race conditions, and
2084 /// should not be used in security-sensitive code on those platforms. All other platforms are
2089 /// See [`fs::remove_file`] and [`fs::remove_dir`].
2091 /// [`fs::remove_file`]: remove_file
2092 /// [`fs::remove_dir`]: remove_dir
2099 /// fn main() -> std::io::Result<()> {
2100 /// fs::remove_dir_all("/some/dir")?;
2104 #[stable(feature = "rust1", since = "1.0.0")]
2105 pub fn remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
2106 fs_imp::remove_dir_all(path.as_ref())
2109 /// Returns an iterator over the entries within a directory.
2111 /// The iterator will yield instances of <code>[io::Result]<[DirEntry]></code>.
2112 /// New errors may be encountered after an iterator is initially constructed.
2113 /// Entries for the current and parent directories (typically `.` and `..`) are
2116 /// # Platform-specific behavior
2118 /// This function currently corresponds to the `opendir` function on Unix
2119 /// and the `FindFirstFile` function on Windows. Advancing the iterator
2120 /// currently corresponds to `readdir` on Unix and `FindNextFile` on Windows.
2121 /// Note that, this [may change in the future][changes].
2123 /// [changes]: io#platform-specific-behavior
2125 /// The order in which this iterator returns entries is platform and filesystem
2130 /// This function will return an error in the following situations, but is not
2131 /// limited to just these cases:
2133 /// * The provided `path` doesn't exist.
2134 /// * The process lacks permissions to view the contents.
2135 /// * The `path` points at a non-directory file.
2141 /// use std::fs::{self, DirEntry};
2142 /// use std::path::Path;
2144 /// // one possible implementation of walking a directory only visiting files
2145 /// fn visit_dirs(dir: &Path, cb: &dyn Fn(&DirEntry)) -> io::Result<()> {
2146 /// if dir.is_dir() {
2147 /// for entry in fs::read_dir(dir)? {
2148 /// let entry = entry?;
2149 /// let path = entry.path();
2150 /// if path.is_dir() {
2151 /// visit_dirs(&path, cb)?;
2162 /// use std::{fs, io};
2164 /// fn main() -> io::Result<()> {
2165 /// let mut entries = fs::read_dir(".")?
2166 /// .map(|res| res.map(|e| e.path()))
2167 /// .collect::<Result<Vec<_>, io::Error>>()?;
2169 /// // The order in which `read_dir` returns entries is not guaranteed. If reproducible
2170 /// // ordering is required the entries should be explicitly sorted.
2174 /// // The entries have now been sorted by their path.
2179 #[stable(feature = "rust1", since = "1.0.0")]
2180 pub fn read_dir<P: AsRef<Path>>(path: P) -> io::Result<ReadDir> {
2181 fs_imp::readdir(path.as_ref()).map(ReadDir)
2184 /// Changes the permissions found on a file or a directory.
2186 /// # Platform-specific behavior
2188 /// This function currently corresponds to the `chmod` function on Unix
2189 /// and the `SetFileAttributes` function on Windows.
2190 /// Note that, this [may change in the future][changes].
2192 /// [changes]: io#platform-specific-behavior
2196 /// This function will return an error in the following situations, but is not
2197 /// limited to just these cases:
2199 /// * `path` does not exist.
2200 /// * The user lacks the permission to change attributes of the file.
2207 /// fn main() -> std::io::Result<()> {
2208 /// let mut perms = fs::metadata("foo.txt")?.permissions();
2209 /// perms.set_readonly(true);
2210 /// fs::set_permissions("foo.txt", perms)?;
2214 #[stable(feature = "set_permissions", since = "1.1.0")]
2215 pub fn set_permissions<P: AsRef<Path>>(path: P, perm: Permissions) -> io::Result<()> {
2216 fs_imp::set_perm(path.as_ref(), perm.0)
2220 /// Creates a new set of options with default mode/security settings for all
2221 /// platforms and also non-recursive.
2226 /// use std::fs::DirBuilder;
2228 /// let builder = DirBuilder::new();
2230 #[stable(feature = "dir_builder", since = "1.6.0")]
2232 pub fn new() -> DirBuilder {
2233 DirBuilder { inner: fs_imp::DirBuilder::new(), recursive: false }
2236 /// Indicates that directories should be created recursively, creating all
2237 /// parent directories. Parents that do not exist are created with the same
2238 /// security and permissions settings.
2240 /// This option defaults to `false`.
2245 /// use std::fs::DirBuilder;
2247 /// let mut builder = DirBuilder::new();
2248 /// builder.recursive(true);
2250 #[stable(feature = "dir_builder", since = "1.6.0")]
2251 pub fn recursive(&mut self, recursive: bool) -> &mut Self {
2252 self.recursive = recursive;
2256 /// Creates the specified directory with the options configured in this
2259 /// It is considered an error if the directory already exists unless
2260 /// recursive mode is enabled.
2265 /// use std::fs::{self, DirBuilder};
2267 /// let path = "/tmp/foo/bar/baz";
2268 /// DirBuilder::new()
2269 /// .recursive(true)
2270 /// .create(path).unwrap();
2272 /// assert!(fs::metadata(path).unwrap().is_dir());
2274 #[stable(feature = "dir_builder", since = "1.6.0")]
2275 pub fn create<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
2276 self._create(path.as_ref())
2279 fn _create(&self, path: &Path) -> io::Result<()> {
2280 if self.recursive { self.create_dir_all(path) } else { self.inner.mkdir(path) }
2283 fn create_dir_all(&self, path: &Path) -> io::Result<()> {
2284 if path == Path::new("") {
2288 match self.inner.mkdir(path) {
2289 Ok(()) => return Ok(()),
2290 Err(ref e) if e.kind() == io::ErrorKind::NotFound => {}
2291 Err(_) if path.is_dir() => return Ok(()),
2292 Err(e) => return Err(e),
2294 match path.parent() {
2295 Some(p) => self.create_dir_all(p)?,
2297 return Err(io::const_io_error!(
2298 io::ErrorKind::Uncategorized,
2299 "failed to create whole tree",
2303 match self.inner.mkdir(path) {
2305 Err(_) if path.is_dir() => Ok(()),
2311 impl AsInnerMut<fs_imp::DirBuilder> for DirBuilder {
2312 fn as_inner_mut(&mut self) -> &mut fs_imp::DirBuilder {
2317 /// Returns `Ok(true)` if the path points at an existing entity.
2319 /// This function will traverse symbolic links to query information about the
2320 /// destination file. In case of broken symbolic links this will return `Ok(false)`.
2322 /// As opposed to the [`Path::exists`] method, this one doesn't silently ignore errors
2323 /// unrelated to the path not existing. (E.g. it will return `Err(_)` in case of permission
2324 /// denied on some of the parent directories.)
2326 /// Note that while this avoids some pitfalls of the `exists()` method, it still can not
2327 /// prevent time-of-check to time-of-use (TOCTOU) bugs. You should only use it in scenarios
2328 /// where those bugs are not an issue.
2333 /// #![feature(fs_try_exists)]
2336 /// assert!(!fs::try_exists("does_not_exist.txt").expect("Can't check existence of file does_not_exist.txt"));
2337 /// assert!(fs::try_exists("/root/secret_file.txt").is_err());
2340 /// [`Path::exists`]: crate::path::Path::exists
2341 // FIXME: stabilization should modify documentation of `exists()` to recommend this method
2343 #[unstable(feature = "fs_try_exists", issue = "83186")]
2345 pub fn try_exists<P: AsRef<Path>>(path: P) -> io::Result<bool> {
2346 fs_imp::try_exists(path.as_ref())