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, BorrowedCursor, IoSlice, IoSliceMut, Read, 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 /// An object providing access 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 /// Creates a new file in read-write mode; error if the file exists.
382 /// This function will create a file if it does not exist, or return an error if it does. This
383 /// way, if the call succeeds, the file returned is guaranteed to be new.
385 /// This option is useful because it is atomic. Otherwise between checking whether a file
386 /// exists and creating a new one, the file may have been created by another process (a TOCTOU
387 /// race condition / attack).
389 /// This can also be written using
390 /// `File::options().read(true).write(true).create_new(true).open(...)`.
395 /// #![feature(file_create_new)]
397 /// use std::fs::File;
399 /// fn main() -> std::io::Result<()> {
400 /// let mut f = File::create_new("foo.txt")?;
404 #[unstable(feature = "file_create_new", issue = "none")]
405 pub fn create_new<P: AsRef<Path>>(path: P) -> io::Result<File> {
406 OpenOptions::new().read(true).write(true).create_new(true).open(path.as_ref())
409 /// Returns a new OpenOptions object.
411 /// This function returns a new OpenOptions object that you can use to
412 /// open or create a file with specific options if `open()` or `create()`
413 /// are not appropriate.
415 /// It is equivalent to `OpenOptions::new()`, but allows you to write more
416 /// readable code. Instead of
417 /// `OpenOptions::new().append(true).open("example.log")`,
418 /// you can write `File::options().append(true).open("example.log")`. This
419 /// also avoids the need to import `OpenOptions`.
421 /// See the [`OpenOptions::new`] function for more details.
426 /// use std::fs::File;
428 /// fn main() -> std::io::Result<()> {
429 /// let mut f = File::options().append(true).open("example.log")?;
434 #[stable(feature = "with_options", since = "1.58.0")]
435 pub fn options() -> OpenOptions {
439 /// Attempts to sync all OS-internal metadata to disk.
441 /// This function will attempt to ensure that all in-memory data reaches the
442 /// filesystem before returning.
444 /// This can be used to handle errors that would otherwise only be caught
445 /// when the `File` is closed. Dropping a file will ignore errors in
446 /// synchronizing this in-memory data.
451 /// use std::fs::File;
452 /// use std::io::prelude::*;
454 /// fn main() -> std::io::Result<()> {
455 /// let mut f = File::create("foo.txt")?;
456 /// f.write_all(b"Hello, world!")?;
462 #[stable(feature = "rust1", since = "1.0.0")]
463 pub fn sync_all(&self) -> io::Result<()> {
467 /// This function is similar to [`sync_all`], except that it might not
468 /// synchronize file metadata to the filesystem.
470 /// This is intended for use cases that must synchronize content, but don't
471 /// need the metadata on disk. The goal of this method is to reduce disk
474 /// Note that some platforms may simply implement this in terms of
477 /// [`sync_all`]: File::sync_all
482 /// use std::fs::File;
483 /// use std::io::prelude::*;
485 /// fn main() -> std::io::Result<()> {
486 /// let mut f = File::create("foo.txt")?;
487 /// f.write_all(b"Hello, world!")?;
493 #[stable(feature = "rust1", since = "1.0.0")]
494 pub fn sync_data(&self) -> io::Result<()> {
495 self.inner.datasync()
498 /// Truncates or extends the underlying file, updating the size of
499 /// this file to become `size`.
501 /// If the `size` is less than the current file's size, then the file will
502 /// be shrunk. If it is greater than the current file's size, then the file
503 /// will be extended to `size` and have all of the intermediate data filled
506 /// The file's cursor isn't changed. In particular, if the cursor was at the
507 /// end and the file is shrunk using this operation, the cursor will now be
512 /// This function will return an error if the file is not opened for writing.
513 /// Also, std::io::ErrorKind::InvalidInput will be returned if the desired
514 /// length would cause an overflow due to the implementation specifics.
519 /// use std::fs::File;
521 /// fn main() -> std::io::Result<()> {
522 /// let mut f = File::create("foo.txt")?;
528 /// Note that this method alters the content of the underlying file, even
529 /// though it takes `&self` rather than `&mut self`.
530 #[stable(feature = "rust1", since = "1.0.0")]
531 pub fn set_len(&self, size: u64) -> io::Result<()> {
532 self.inner.truncate(size)
535 /// Queries metadata about the underlying file.
540 /// use std::fs::File;
542 /// fn main() -> std::io::Result<()> {
543 /// let mut f = File::open("foo.txt")?;
544 /// let metadata = f.metadata()?;
548 #[stable(feature = "rust1", since = "1.0.0")]
549 pub fn metadata(&self) -> io::Result<Metadata> {
550 self.inner.file_attr().map(Metadata)
553 /// Creates a new `File` instance that shares the same underlying file handle
554 /// as the existing `File` instance. Reads, writes, and seeks will affect
555 /// both `File` instances simultaneously.
559 /// Creates two handles for a file named `foo.txt`:
562 /// use std::fs::File;
564 /// fn main() -> std::io::Result<()> {
565 /// let mut file = File::open("foo.txt")?;
566 /// let file_copy = file.try_clone()?;
571 /// Assuming there’s a file named `foo.txt` with contents `abcdef\n`, create
572 /// two handles, seek one of them, and read the remaining bytes from the
576 /// use std::fs::File;
577 /// use std::io::SeekFrom;
578 /// use std::io::prelude::*;
580 /// fn main() -> std::io::Result<()> {
581 /// let mut file = File::open("foo.txt")?;
582 /// let mut file_copy = file.try_clone()?;
584 /// file.seek(SeekFrom::Start(3))?;
586 /// let mut contents = vec![];
587 /// file_copy.read_to_end(&mut contents)?;
588 /// assert_eq!(contents, b"def\n");
592 #[stable(feature = "file_try_clone", since = "1.9.0")]
593 pub fn try_clone(&self) -> io::Result<File> {
594 Ok(File { inner: self.inner.duplicate()? })
597 /// Changes the permissions on the underlying file.
599 /// # Platform-specific behavior
601 /// This function currently corresponds to the `fchmod` function on Unix and
602 /// the `SetFileInformationByHandle` function on Windows. Note that, this
603 /// [may change in the future][changes].
605 /// [changes]: io#platform-specific-behavior
609 /// This function will return an error if the user lacks permission change
610 /// attributes on the underlying file. It may also return an error in other
611 /// os-specific unspecified cases.
616 /// fn main() -> std::io::Result<()> {
617 /// use std::fs::File;
619 /// let file = File::open("foo.txt")?;
620 /// let mut perms = file.metadata()?.permissions();
621 /// perms.set_readonly(true);
622 /// file.set_permissions(perms)?;
627 /// Note that this method alters the permissions of the underlying file,
628 /// even though it takes `&self` rather than `&mut self`.
629 #[stable(feature = "set_permissions_atomic", since = "1.16.0")]
630 pub fn set_permissions(&self, perm: Permissions) -> io::Result<()> {
631 self.inner.set_permissions(perm.0)
634 /// Changes the timestamps of the underlying file.
636 /// # Platform-specific behavior
638 /// This function currently corresponds to the `futimens` function on Unix (falling back to
639 /// `futimes` on macOS before 10.13) and the `SetFileTime` function on Windows. Note that this
640 /// [may change in the future][changes].
642 /// [changes]: io#platform-specific-behavior
646 /// This function will return an error if the user lacks permission to change timestamps on the
647 /// underlying file. It may also return an error in other os-specific unspecified cases.
649 /// This function may return an error if the operating system lacks support to change one or
650 /// more of the timestamps set in the `FileTimes` structure.
655 /// #![feature(file_set_times)]
657 /// fn main() -> std::io::Result<()> {
658 /// use std::fs::{self, File, FileTimes};
660 /// let src = fs::metadata("src")?;
661 /// let dest = File::options().write(true).open("dest")?;
662 /// let times = FileTimes::new()
663 /// .set_accessed(src.accessed()?)
664 /// .set_modified(src.modified()?);
665 /// dest.set_times(times)?;
669 #[unstable(feature = "file_set_times", issue = "98245")]
670 #[doc(alias = "futimens")]
671 #[doc(alias = "futimes")]
672 #[doc(alias = "SetFileTime")]
673 pub fn set_times(&self, times: FileTimes) -> io::Result<()> {
674 self.inner.set_times(times.0)
677 /// Changes the modification time of the underlying file.
679 /// This is an alias for `set_times(FileTimes::new().set_modified(time))`.
680 #[unstable(feature = "file_set_times", issue = "98245")]
682 pub fn set_modified(&self, time: SystemTime) -> io::Result<()> {
683 self.set_times(FileTimes::new().set_modified(time))
687 // In addition to the `impl`s here, `File` also has `impl`s for
688 // `AsFd`/`From<OwnedFd>`/`Into<OwnedFd>` and
689 // `AsRawFd`/`IntoRawFd`/`FromRawFd`, on Unix and WASI, and
690 // `AsHandle`/`From<OwnedHandle>`/`Into<OwnedHandle>` and
691 // `AsRawHandle`/`IntoRawHandle`/`FromRawHandle` on Windows.
693 impl AsInner<fs_imp::File> for File {
694 fn as_inner(&self) -> &fs_imp::File {
698 impl FromInner<fs_imp::File> for File {
699 fn from_inner(f: fs_imp::File) -> File {
703 impl IntoInner<fs_imp::File> for File {
704 fn into_inner(self) -> fs_imp::File {
709 #[stable(feature = "rust1", since = "1.0.0")]
710 impl fmt::Debug for File {
711 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
716 /// Indicates how much extra capacity is needed to read the rest of the file.
717 fn buffer_capacity_required(mut file: &File) -> usize {
718 let size = file.metadata().map(|m| m.len()).unwrap_or(0);
719 let pos = file.stream_position().unwrap_or(0);
720 // Don't worry about `usize` overflow because reading will fail regardless
722 size.saturating_sub(pos) as usize
725 #[stable(feature = "rust1", since = "1.0.0")]
727 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
731 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
732 self.inner.read_vectored(bufs)
735 fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
736 self.inner.read_buf(cursor)
740 fn is_read_vectored(&self) -> bool {
741 self.inner.is_read_vectored()
744 // Reserves space in the buffer based on the file size when available.
745 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
746 buf.reserve(buffer_capacity_required(self));
747 io::default_read_to_end(self, buf)
750 // Reserves space in the buffer based on the file size when available.
751 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
752 buf.reserve(buffer_capacity_required(self));
753 io::default_read_to_string(self, buf)
756 #[stable(feature = "rust1", since = "1.0.0")]
757 impl Write for File {
758 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
759 self.inner.write(buf)
762 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
763 self.inner.write_vectored(bufs)
767 fn is_write_vectored(&self) -> bool {
768 self.inner.is_write_vectored()
771 fn flush(&mut self) -> io::Result<()> {
775 #[stable(feature = "rust1", since = "1.0.0")]
777 fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
781 #[stable(feature = "rust1", since = "1.0.0")]
782 impl Read for &File {
783 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
787 fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
788 self.inner.read_buf(cursor)
791 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
792 self.inner.read_vectored(bufs)
796 fn is_read_vectored(&self) -> bool {
797 self.inner.is_read_vectored()
800 // Reserves space in the buffer based on the file size when available.
801 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
802 buf.reserve(buffer_capacity_required(self));
803 io::default_read_to_end(self, buf)
806 // Reserves space in the buffer based on the file size when available.
807 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
808 buf.reserve(buffer_capacity_required(self));
809 io::default_read_to_string(self, buf)
812 #[stable(feature = "rust1", since = "1.0.0")]
813 impl Write for &File {
814 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
815 self.inner.write(buf)
818 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
819 self.inner.write_vectored(bufs)
823 fn is_write_vectored(&self) -> bool {
824 self.inner.is_write_vectored()
827 fn flush(&mut self) -> io::Result<()> {
831 #[stable(feature = "rust1", since = "1.0.0")]
832 impl Seek for &File {
833 fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
839 /// Creates a blank new set of options ready for configuration.
841 /// All options are initially set to `false`.
846 /// use std::fs::OpenOptions;
848 /// let mut options = OpenOptions::new();
849 /// let file = options.read(true).open("foo.txt");
851 #[stable(feature = "rust1", since = "1.0.0")]
853 pub fn new() -> Self {
854 OpenOptions(fs_imp::OpenOptions::new())
857 /// Sets the option for read access.
859 /// This option, when true, will indicate that the file should be
860 /// `read`-able if opened.
865 /// use std::fs::OpenOptions;
867 /// let file = OpenOptions::new().read(true).open("foo.txt");
869 #[stable(feature = "rust1", since = "1.0.0")]
870 pub fn read(&mut self, read: bool) -> &mut Self {
875 /// Sets the option for write access.
877 /// This option, when true, will indicate that the file should be
878 /// `write`-able if opened.
880 /// If the file already exists, any write calls on it will overwrite its
881 /// contents, without truncating it.
886 /// use std::fs::OpenOptions;
888 /// let file = OpenOptions::new().write(true).open("foo.txt");
890 #[stable(feature = "rust1", since = "1.0.0")]
891 pub fn write(&mut self, write: bool) -> &mut Self {
896 /// Sets the option for the append mode.
898 /// This option, when true, means that writes will append to a file instead
899 /// of overwriting previous contents.
900 /// Note that setting `.write(true).append(true)` has the same effect as
901 /// setting only `.append(true)`.
903 /// For most filesystems, the operating system guarantees that all writes are
904 /// atomic: no writes get mangled because another process writes at the same
907 /// One maybe obvious note when using append-mode: make sure that all data
908 /// that belongs together is written to the file in one operation. This
909 /// can be done by concatenating strings before passing them to [`write()`],
910 /// or using a buffered writer (with a buffer of adequate size),
911 /// and calling [`flush()`] when the message is complete.
913 /// If a file is opened with both read and append access, beware that after
914 /// opening, and after every write, the position for reading may be set at the
915 /// end of the file. So, before writing, save the current position (using
916 /// <code>[seek]\([SeekFrom]::[Current]\(0))</code>), and restore it before the next read.
920 /// This function doesn't create the file if it doesn't exist. Use the
921 /// [`OpenOptions::create`] method to do so.
923 /// [`write()`]: Write::write "io::Write::write"
924 /// [`flush()`]: Write::flush "io::Write::flush"
925 /// [seek]: Seek::seek "io::Seek::seek"
926 /// [Current]: SeekFrom::Current "io::SeekFrom::Current"
931 /// use std::fs::OpenOptions;
933 /// let file = OpenOptions::new().append(true).open("foo.txt");
935 #[stable(feature = "rust1", since = "1.0.0")]
936 pub fn append(&mut self, append: bool) -> &mut Self {
937 self.0.append(append);
941 /// Sets the option for truncating a previous file.
943 /// If a file is successfully opened with this option set it will truncate
944 /// the file to 0 length if it already exists.
946 /// The file must be opened with write access for truncate to work.
951 /// use std::fs::OpenOptions;
953 /// let file = OpenOptions::new().write(true).truncate(true).open("foo.txt");
955 #[stable(feature = "rust1", since = "1.0.0")]
956 pub fn truncate(&mut self, truncate: bool) -> &mut Self {
957 self.0.truncate(truncate);
961 /// Sets the option to create a new file, or open it if it already exists.
963 /// In order for the file to be created, [`OpenOptions::write`] or
964 /// [`OpenOptions::append`] access must be used.
969 /// use std::fs::OpenOptions;
971 /// let file = OpenOptions::new().write(true).create(true).open("foo.txt");
973 #[stable(feature = "rust1", since = "1.0.0")]
974 pub fn create(&mut self, create: bool) -> &mut Self {
975 self.0.create(create);
979 /// Sets the option to create a new file, failing if it already exists.
981 /// No file is allowed to exist at the target location, also no (dangling) symlink. In this
982 /// way, if the call succeeds, the file returned is guaranteed to be new.
984 /// This option is useful because it is atomic. Otherwise between checking
985 /// whether a file exists and creating a new one, the file may have been
986 /// created by another process (a TOCTOU race condition / attack).
988 /// If `.create_new(true)` is set, [`.create()`] and [`.truncate()`] are
991 /// The file must be opened with write or append access in order to create
994 /// [`.create()`]: OpenOptions::create
995 /// [`.truncate()`]: OpenOptions::truncate
1000 /// use std::fs::OpenOptions;
1002 /// let file = OpenOptions::new().write(true)
1003 /// .create_new(true)
1004 /// .open("foo.txt");
1006 #[stable(feature = "expand_open_options2", since = "1.9.0")]
1007 pub fn create_new(&mut self, create_new: bool) -> &mut Self {
1008 self.0.create_new(create_new);
1012 /// Opens a file at `path` with the options specified by `self`.
1016 /// This function will return an error under a number of different
1017 /// circumstances. Some of these error conditions are listed here, together
1018 /// with their [`io::ErrorKind`]. The mapping to [`io::ErrorKind`]s is not
1019 /// part of the compatibility contract of the function.
1021 /// * [`NotFound`]: The specified file does not exist and neither `create`
1022 /// or `create_new` is set.
1023 /// * [`NotFound`]: One of the directory components of the file path does
1025 /// * [`PermissionDenied`]: The user lacks permission to get the specified
1026 /// access rights for the file.
1027 /// * [`PermissionDenied`]: The user lacks permission to open one of the
1028 /// directory components of the specified path.
1029 /// * [`AlreadyExists`]: `create_new` was specified and the file already
1031 /// * [`InvalidInput`]: Invalid combinations of open options (truncate
1032 /// without write access, no access mode set, etc.).
1034 /// The following errors don't match any existing [`io::ErrorKind`] at the moment:
1035 /// * One of the directory components of the specified file path
1036 /// was not, in fact, a directory.
1037 /// * Filesystem-level errors: full disk, write permission
1038 /// requested on a read-only file system, exceeded disk quota, too many
1039 /// open files, too long filename, too many symbolic links in the
1040 /// specified path (Unix-like systems only), etc.
1045 /// use std::fs::OpenOptions;
1047 /// let file = OpenOptions::new().read(true).open("foo.txt");
1050 /// [`AlreadyExists`]: io::ErrorKind::AlreadyExists
1051 /// [`InvalidInput`]: io::ErrorKind::InvalidInput
1052 /// [`NotFound`]: io::ErrorKind::NotFound
1053 /// [`PermissionDenied`]: io::ErrorKind::PermissionDenied
1054 #[stable(feature = "rust1", since = "1.0.0")]
1055 pub fn open<P: AsRef<Path>>(&self, path: P) -> io::Result<File> {
1056 self._open(path.as_ref())
1059 fn _open(&self, path: &Path) -> io::Result<File> {
1060 fs_imp::File::open(path, &self.0).map(|inner| File { inner })
1064 impl AsInner<fs_imp::OpenOptions> for OpenOptions {
1065 fn as_inner(&self) -> &fs_imp::OpenOptions {
1070 impl AsInnerMut<fs_imp::OpenOptions> for OpenOptions {
1071 fn as_inner_mut(&mut self) -> &mut fs_imp::OpenOptions {
1077 /// Returns the file type for this metadata.
1082 /// fn main() -> std::io::Result<()> {
1085 /// let metadata = fs::metadata("foo.txt")?;
1087 /// println!("{:?}", metadata.file_type());
1092 #[stable(feature = "file_type", since = "1.1.0")]
1093 pub fn file_type(&self) -> FileType {
1094 FileType(self.0.file_type())
1097 /// Returns `true` if this metadata is for a directory. The
1098 /// result is mutually exclusive to the result of
1099 /// [`Metadata::is_file`], and will be false for symlink metadata
1100 /// obtained from [`symlink_metadata`].
1105 /// fn main() -> std::io::Result<()> {
1108 /// let metadata = fs::metadata("foo.txt")?;
1110 /// assert!(!metadata.is_dir());
1115 #[stable(feature = "rust1", since = "1.0.0")]
1116 pub fn is_dir(&self) -> bool {
1117 self.file_type().is_dir()
1120 /// Returns `true` if this metadata is for a regular file. The
1121 /// result is mutually exclusive to the result of
1122 /// [`Metadata::is_dir`], and will be false for symlink metadata
1123 /// obtained from [`symlink_metadata`].
1125 /// When the goal is simply to read from (or write to) the source, the most
1126 /// reliable way to test the source can be read (or written to) is to open
1127 /// it. Only using `is_file` can break workflows like `diff <( prog_a )` on
1128 /// a Unix-like system for example. See [`File::open`] or
1129 /// [`OpenOptions::open`] for more information.
1136 /// fn main() -> std::io::Result<()> {
1137 /// let metadata = fs::metadata("foo.txt")?;
1139 /// assert!(metadata.is_file());
1144 #[stable(feature = "rust1", since = "1.0.0")]
1145 pub fn is_file(&self) -> bool {
1146 self.file_type().is_file()
1149 /// Returns `true` if this metadata is for a symbolic link.
1153 #[cfg_attr(unix, doc = "```no_run")]
1154 #[cfg_attr(not(unix), doc = "```ignore")]
1156 /// use std::path::Path;
1157 /// use std::os::unix::fs::symlink;
1159 /// fn main() -> std::io::Result<()> {
1160 /// let link_path = Path::new("link");
1161 /// symlink("/origin_does_not_exist/", link_path)?;
1163 /// let metadata = fs::symlink_metadata(link_path)?;
1165 /// assert!(metadata.is_symlink());
1170 #[stable(feature = "is_symlink", since = "1.58.0")]
1171 pub fn is_symlink(&self) -> bool {
1172 self.file_type().is_symlink()
1175 /// Returns the size of the file, in bytes, this metadata is for.
1182 /// fn main() -> std::io::Result<()> {
1183 /// let metadata = fs::metadata("foo.txt")?;
1185 /// assert_eq!(0, metadata.len());
1190 #[stable(feature = "rust1", since = "1.0.0")]
1191 pub fn len(&self) -> u64 {
1195 /// Returns the permissions of the file this metadata is for.
1202 /// fn main() -> std::io::Result<()> {
1203 /// let metadata = fs::metadata("foo.txt")?;
1205 /// assert!(!metadata.permissions().readonly());
1210 #[stable(feature = "rust1", since = "1.0.0")]
1211 pub fn permissions(&self) -> Permissions {
1212 Permissions(self.0.perm())
1215 /// Returns the last modification time listed in this metadata.
1217 /// The returned value corresponds to the `mtime` field of `stat` on Unix
1218 /// platforms and the `ftLastWriteTime` field on Windows platforms.
1222 /// This field might not be available on all platforms, and will return an
1223 /// `Err` on platforms where it is not available.
1230 /// fn main() -> std::io::Result<()> {
1231 /// let metadata = fs::metadata("foo.txt")?;
1233 /// if let Ok(time) = metadata.modified() {
1234 /// println!("{time:?}");
1236 /// println!("Not supported on this platform");
1241 #[stable(feature = "fs_time", since = "1.10.0")]
1242 pub fn modified(&self) -> io::Result<SystemTime> {
1243 self.0.modified().map(FromInner::from_inner)
1246 /// Returns the last access time of this metadata.
1248 /// The returned value corresponds to the `atime` field of `stat` on Unix
1249 /// platforms and the `ftLastAccessTime` field on Windows platforms.
1251 /// Note that not all platforms will keep this field update in a file's
1252 /// metadata, for example Windows has an option to disable updating this
1253 /// time when files are accessed and Linux similarly has `noatime`.
1257 /// This field might not be available on all platforms, and will return an
1258 /// `Err` on platforms where it is not available.
1265 /// fn main() -> std::io::Result<()> {
1266 /// let metadata = fs::metadata("foo.txt")?;
1268 /// if let Ok(time) = metadata.accessed() {
1269 /// println!("{time:?}");
1271 /// println!("Not supported on this platform");
1276 #[stable(feature = "fs_time", since = "1.10.0")]
1277 pub fn accessed(&self) -> io::Result<SystemTime> {
1278 self.0.accessed().map(FromInner::from_inner)
1281 /// Returns the creation time listed in this metadata.
1283 /// The returned value corresponds to the `btime` field of `statx` on
1284 /// Linux kernel starting from to 4.11, the `birthtime` field of `stat` on other
1285 /// Unix platforms, and the `ftCreationTime` field on Windows platforms.
1289 /// This field might not be available on all platforms, and will return an
1290 /// `Err` on platforms or filesystems where it is not available.
1297 /// fn main() -> std::io::Result<()> {
1298 /// let metadata = fs::metadata("foo.txt")?;
1300 /// if let Ok(time) = metadata.created() {
1301 /// println!("{time:?}");
1303 /// println!("Not supported on this platform or filesystem");
1308 #[stable(feature = "fs_time", since = "1.10.0")]
1309 pub fn created(&self) -> io::Result<SystemTime> {
1310 self.0.created().map(FromInner::from_inner)
1314 #[stable(feature = "std_debug", since = "1.16.0")]
1315 impl fmt::Debug for Metadata {
1316 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1317 f.debug_struct("Metadata")
1318 .field("file_type", &self.file_type())
1319 .field("is_dir", &self.is_dir())
1320 .field("is_file", &self.is_file())
1321 .field("permissions", &self.permissions())
1322 .field("modified", &self.modified())
1323 .field("accessed", &self.accessed())
1324 .field("created", &self.created())
1325 .finish_non_exhaustive()
1329 impl AsInner<fs_imp::FileAttr> for Metadata {
1330 fn as_inner(&self) -> &fs_imp::FileAttr {
1335 impl FromInner<fs_imp::FileAttr> for Metadata {
1336 fn from_inner(attr: fs_imp::FileAttr) -> Metadata {
1342 /// Create a new `FileTimes` with no times set.
1344 /// Using the resulting `FileTimes` in [`File::set_times`] will not modify any timestamps.
1345 #[unstable(feature = "file_set_times", issue = "98245")]
1346 pub fn new() -> Self {
1350 /// Set the last access time of a file.
1351 #[unstable(feature = "file_set_times", issue = "98245")]
1352 pub fn set_accessed(mut self, t: SystemTime) -> Self {
1353 self.0.set_accessed(t.into_inner());
1357 /// Set the last modified time of a file.
1358 #[unstable(feature = "file_set_times", issue = "98245")]
1359 pub fn set_modified(mut self, t: SystemTime) -> Self {
1360 self.0.set_modified(t.into_inner());
1366 /// Returns `true` if these permissions describe a readonly (unwritable) file.
1371 /// use std::fs::File;
1373 /// fn main() -> std::io::Result<()> {
1374 /// let mut f = File::create("foo.txt")?;
1375 /// let metadata = f.metadata()?;
1377 /// assert_eq!(false, metadata.permissions().readonly());
1381 #[must_use = "call `set_readonly` to modify the readonly flag"]
1382 #[stable(feature = "rust1", since = "1.0.0")]
1383 pub fn readonly(&self) -> bool {
1387 /// Modifies the readonly flag for this set of permissions. If the
1388 /// `readonly` argument is `true`, using the resulting `Permission` will
1389 /// update file permissions to forbid writing. Conversely, if it's `false`,
1390 /// using the resulting `Permission` will update file permissions to allow
1393 /// This operation does **not** modify the filesystem. To modify the
1394 /// filesystem use the [`set_permissions`] function.
1399 /// use std::fs::File;
1401 /// fn main() -> std::io::Result<()> {
1402 /// let f = File::create("foo.txt")?;
1403 /// let metadata = f.metadata()?;
1404 /// let mut permissions = metadata.permissions();
1406 /// permissions.set_readonly(true);
1408 /// // filesystem doesn't change
1409 /// assert_eq!(false, metadata.permissions().readonly());
1411 /// // just this particular `permissions`.
1412 /// assert_eq!(true, permissions.readonly());
1416 #[stable(feature = "rust1", since = "1.0.0")]
1417 pub fn set_readonly(&mut self, readonly: bool) {
1418 self.0.set_readonly(readonly)
1423 /// Tests whether this file type represents a directory. The
1424 /// result is mutually exclusive to the results of
1425 /// [`is_file`] and [`is_symlink`]; only zero or one of these
1428 /// [`is_file`]: FileType::is_file
1429 /// [`is_symlink`]: FileType::is_symlink
1434 /// fn main() -> std::io::Result<()> {
1437 /// let metadata = fs::metadata("foo.txt")?;
1438 /// let file_type = metadata.file_type();
1440 /// assert_eq!(file_type.is_dir(), false);
1445 #[stable(feature = "file_type", since = "1.1.0")]
1446 pub fn is_dir(&self) -> bool {
1450 /// Tests whether this file type represents a regular file.
1451 /// The result is mutually exclusive to the results of
1452 /// [`is_dir`] and [`is_symlink`]; only zero or one of these
1455 /// When the goal is simply to read from (or write to) the source, the most
1456 /// reliable way to test the source can be read (or written to) is to open
1457 /// it. Only using `is_file` can break workflows like `diff <( prog_a )` on
1458 /// a Unix-like system for example. See [`File::open`] or
1459 /// [`OpenOptions::open`] for more information.
1461 /// [`is_dir`]: FileType::is_dir
1462 /// [`is_symlink`]: FileType::is_symlink
1467 /// fn main() -> std::io::Result<()> {
1470 /// let metadata = fs::metadata("foo.txt")?;
1471 /// let file_type = metadata.file_type();
1473 /// assert_eq!(file_type.is_file(), true);
1478 #[stable(feature = "file_type", since = "1.1.0")]
1479 pub fn is_file(&self) -> bool {
1483 /// Tests whether this file type represents a symbolic link.
1484 /// The result is mutually exclusive to the results of
1485 /// [`is_dir`] and [`is_file`]; only zero or one of these
1488 /// The underlying [`Metadata`] struct needs to be retrieved
1489 /// with the [`fs::symlink_metadata`] function and not the
1490 /// [`fs::metadata`] function. The [`fs::metadata`] function
1491 /// follows symbolic links, so [`is_symlink`] would always
1492 /// return `false` for the target file.
1494 /// [`fs::metadata`]: metadata
1495 /// [`fs::symlink_metadata`]: symlink_metadata
1496 /// [`is_dir`]: FileType::is_dir
1497 /// [`is_file`]: FileType::is_file
1498 /// [`is_symlink`]: FileType::is_symlink
1505 /// fn main() -> std::io::Result<()> {
1506 /// let metadata = fs::symlink_metadata("foo.txt")?;
1507 /// let file_type = metadata.file_type();
1509 /// assert_eq!(file_type.is_symlink(), false);
1514 #[stable(feature = "file_type", since = "1.1.0")]
1515 pub fn is_symlink(&self) -> bool {
1520 impl AsInner<fs_imp::FileType> for FileType {
1521 fn as_inner(&self) -> &fs_imp::FileType {
1526 impl FromInner<fs_imp::FilePermissions> for Permissions {
1527 fn from_inner(f: fs_imp::FilePermissions) -> Permissions {
1532 impl AsInner<fs_imp::FilePermissions> for Permissions {
1533 fn as_inner(&self) -> &fs_imp::FilePermissions {
1538 #[stable(feature = "rust1", since = "1.0.0")]
1539 impl Iterator for ReadDir {
1540 type Item = io::Result<DirEntry>;
1542 fn next(&mut self) -> Option<io::Result<DirEntry>> {
1543 self.0.next().map(|entry| entry.map(DirEntry))
1548 /// Returns the full path to the file that this entry represents.
1550 /// The full path is created by joining the original path to `read_dir`
1551 /// with the filename of this entry.
1558 /// fn main() -> std::io::Result<()> {
1559 /// for entry in fs::read_dir(".")? {
1560 /// let dir = entry?;
1561 /// println!("{:?}", dir.path());
1567 /// This prints output like:
1570 /// "./whatever.txt"
1572 /// "./hello_world.rs"
1575 /// The exact text, of course, depends on what files you have in `.`.
1577 #[stable(feature = "rust1", since = "1.0.0")]
1578 pub fn path(&self) -> PathBuf {
1582 /// Returns the metadata for the file that this entry points at.
1584 /// This function will not traverse symlinks if this entry points at a
1585 /// symlink. To traverse symlinks use [`fs::metadata`] or [`fs::File::metadata`].
1587 /// [`fs::metadata`]: metadata
1588 /// [`fs::File::metadata`]: File::metadata
1590 /// # Platform-specific behavior
1592 /// On Windows this function is cheap to call (no extra system calls
1593 /// needed), but on Unix platforms this function is the equivalent of
1594 /// calling `symlink_metadata` on the path.
1601 /// if let Ok(entries) = fs::read_dir(".") {
1602 /// for entry in entries {
1603 /// if let Ok(entry) = entry {
1604 /// // Here, `entry` is a `DirEntry`.
1605 /// if let Ok(metadata) = entry.metadata() {
1606 /// // Now let's show our entry's permissions!
1607 /// println!("{:?}: {:?}", entry.path(), metadata.permissions());
1609 /// println!("Couldn't get metadata for {:?}", entry.path());
1615 #[stable(feature = "dir_entry_ext", since = "1.1.0")]
1616 pub fn metadata(&self) -> io::Result<Metadata> {
1617 self.0.metadata().map(Metadata)
1620 /// Returns the file type for the file that this entry points at.
1622 /// This function will not traverse symlinks if this entry points at a
1625 /// # Platform-specific behavior
1627 /// On Windows and most Unix platforms this function is free (no extra
1628 /// system calls needed), but some Unix platforms may require the equivalent
1629 /// call to `symlink_metadata` to learn about the target file type.
1636 /// if let Ok(entries) = fs::read_dir(".") {
1637 /// for entry in entries {
1638 /// if let Ok(entry) = entry {
1639 /// // Here, `entry` is a `DirEntry`.
1640 /// if let Ok(file_type) = entry.file_type() {
1641 /// // Now let's show our entry's file type!
1642 /// println!("{:?}: {:?}", entry.path(), file_type);
1644 /// println!("Couldn't get file type for {:?}", entry.path());
1650 #[stable(feature = "dir_entry_ext", since = "1.1.0")]
1651 pub fn file_type(&self) -> io::Result<FileType> {
1652 self.0.file_type().map(FileType)
1655 /// Returns the bare file name of this directory entry without any other
1656 /// leading path component.
1663 /// if let Ok(entries) = fs::read_dir(".") {
1664 /// for entry in entries {
1665 /// if let Ok(entry) = entry {
1666 /// // Here, `entry` is a `DirEntry`.
1667 /// println!("{:?}", entry.file_name());
1673 #[stable(feature = "dir_entry_ext", since = "1.1.0")]
1674 pub fn file_name(&self) -> OsString {
1679 #[stable(feature = "dir_entry_debug", since = "1.13.0")]
1680 impl fmt::Debug for DirEntry {
1681 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1682 f.debug_tuple("DirEntry").field(&self.path()).finish()
1686 impl AsInner<fs_imp::DirEntry> for DirEntry {
1687 fn as_inner(&self) -> &fs_imp::DirEntry {
1692 /// Removes a file from the filesystem.
1694 /// Note that there is no
1695 /// guarantee that the file is immediately deleted (e.g., depending on
1696 /// platform, other open file descriptors may prevent immediate removal).
1698 /// # Platform-specific behavior
1700 /// This function currently corresponds to the `unlink` function on Unix
1701 /// and the `DeleteFile` function on Windows.
1702 /// Note that, this [may change in the future][changes].
1704 /// [changes]: io#platform-specific-behavior
1708 /// This function will return an error in the following situations, but is not
1709 /// limited to just these cases:
1711 /// * `path` points to a directory.
1712 /// * The file doesn't exist.
1713 /// * The user lacks permissions to remove the file.
1720 /// fn main() -> std::io::Result<()> {
1721 /// fs::remove_file("a.txt")?;
1725 #[stable(feature = "rust1", since = "1.0.0")]
1726 pub fn remove_file<P: AsRef<Path>>(path: P) -> io::Result<()> {
1727 fs_imp::unlink(path.as_ref())
1730 /// Given a path, query the file system to get information about a file,
1733 /// This function will traverse symbolic links to query information about the
1734 /// destination file.
1736 /// # Platform-specific behavior
1738 /// This function currently corresponds to the `stat` function on Unix
1739 /// and the `GetFileInformationByHandle` function on Windows.
1740 /// Note that, this [may change in the future][changes].
1742 /// [changes]: io#platform-specific-behavior
1746 /// This function will return an error in the following situations, but is not
1747 /// limited to just these cases:
1749 /// * The user lacks permissions to perform `metadata` call on `path`.
1750 /// * `path` does not exist.
1757 /// fn main() -> std::io::Result<()> {
1758 /// let attr = fs::metadata("/some/file/path.txt")?;
1759 /// // inspect attr ...
1763 #[stable(feature = "rust1", since = "1.0.0")]
1764 pub fn metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
1765 fs_imp::stat(path.as_ref()).map(Metadata)
1768 /// Query the metadata about a file without following symlinks.
1770 /// # Platform-specific behavior
1772 /// This function currently corresponds to the `lstat` function on Unix
1773 /// and the `GetFileInformationByHandle` function on Windows.
1774 /// Note that, this [may change in the future][changes].
1776 /// [changes]: io#platform-specific-behavior
1780 /// This function will return an error in the following situations, but is not
1781 /// limited to just these cases:
1783 /// * The user lacks permissions to perform `metadata` call on `path`.
1784 /// * `path` does not exist.
1791 /// fn main() -> std::io::Result<()> {
1792 /// let attr = fs::symlink_metadata("/some/file/path.txt")?;
1793 /// // inspect attr ...
1797 #[stable(feature = "symlink_metadata", since = "1.1.0")]
1798 pub fn symlink_metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
1799 fs_imp::lstat(path.as_ref()).map(Metadata)
1802 /// Rename a file or directory to a new name, replacing the original file if
1803 /// `to` already exists.
1805 /// This will not work if the new name is on a different mount point.
1807 /// # Platform-specific behavior
1809 /// This function currently corresponds to the `rename` function on Unix
1810 /// and the `MoveFileEx` function with the `MOVEFILE_REPLACE_EXISTING` flag on Windows.
1812 /// Because of this, the behavior when both `from` and `to` exist differs. On
1813 /// Unix, if `from` is a directory, `to` must also be an (empty) directory. If
1814 /// `from` is not a directory, `to` must also be not a directory. In contrast,
1815 /// on Windows, `from` can be anything, but `to` must *not* be a directory.
1817 /// Note that, this [may change in the future][changes].
1819 /// [changes]: io#platform-specific-behavior
1823 /// This function will return an error in the following situations, but is not
1824 /// limited to just these cases:
1826 /// * `from` does not exist.
1827 /// * The user lacks permissions to view contents.
1828 /// * `from` and `to` are on separate filesystems.
1835 /// fn main() -> std::io::Result<()> {
1836 /// fs::rename("a.txt", "b.txt")?; // Rename a.txt to b.txt
1840 #[stable(feature = "rust1", since = "1.0.0")]
1841 pub fn rename<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()> {
1842 fs_imp::rename(from.as_ref(), to.as_ref())
1845 /// Copies the contents of one file to another. This function will also
1846 /// copy the permission bits of the original file to the destination file.
1848 /// This function will **overwrite** the contents of `to`.
1850 /// Note that if `from` and `to` both point to the same file, then the file
1851 /// will likely get truncated by this operation.
1853 /// On success, the total number of bytes copied is returned and it is equal to
1854 /// the length of the `to` file as reported by `metadata`.
1856 /// If you’re wanting to copy the contents of one file to another and you’re
1857 /// working with [`File`]s, see the [`io::copy()`] function.
1859 /// # Platform-specific behavior
1861 /// This function currently corresponds to the `open` function in Unix
1862 /// with `O_RDONLY` for `from` and `O_WRONLY`, `O_CREAT`, and `O_TRUNC` for `to`.
1863 /// `O_CLOEXEC` is set for returned file descriptors.
1865 /// On Linux (including Android), this function attempts to use `copy_file_range(2)`,
1866 /// and falls back to reading and writing if that is not possible.
1868 /// On Windows, this function currently corresponds to `CopyFileEx`. Alternate
1869 /// NTFS streams are copied but only the size of the main stream is returned by
1872 /// On MacOS, this function corresponds to `fclonefileat` and `fcopyfile`.
1874 /// Note that platform-specific behavior [may change in the future][changes].
1876 /// [changes]: io#platform-specific-behavior
1880 /// This function will return an error in the following situations, but is not
1881 /// limited to just these cases:
1883 /// * `from` is neither a regular file nor a symlink to a regular file.
1884 /// * `from` does not exist.
1885 /// * The current process does not have the permission rights to read
1886 /// `from` or write `to`.
1893 /// fn main() -> std::io::Result<()> {
1894 /// fs::copy("foo.txt", "bar.txt")?; // Copy foo.txt to bar.txt
1898 #[stable(feature = "rust1", since = "1.0.0")]
1899 pub fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<u64> {
1900 fs_imp::copy(from.as_ref(), to.as_ref())
1903 /// Creates a new hard link on the filesystem.
1905 /// The `link` path will be a link pointing to the `original` path. Note that
1906 /// systems often require these two paths to both be located on the same
1909 /// If `original` names a symbolic link, it is platform-specific whether the
1910 /// symbolic link is followed. On platforms where it's possible to not follow
1911 /// it, it is not followed, and the created hard link points to the symbolic
1914 /// # Platform-specific behavior
1916 /// This function currently corresponds the `CreateHardLink` function on Windows.
1917 /// On most Unix systems, it corresponds to the `linkat` function with no flags.
1918 /// On Android, VxWorks, and Redox, it instead corresponds to the `link` function.
1919 /// On MacOS, it uses the `linkat` function if it is available, but on very old
1920 /// systems where `linkat` is not available, `link` is selected at runtime instead.
1921 /// Note that, this [may change in the future][changes].
1923 /// [changes]: io#platform-specific-behavior
1927 /// This function will return an error in the following situations, but is not
1928 /// limited to just these cases:
1930 /// * The `original` path is not a file or doesn't exist.
1937 /// fn main() -> std::io::Result<()> {
1938 /// fs::hard_link("a.txt", "b.txt")?; // Hard link a.txt to b.txt
1942 #[stable(feature = "rust1", since = "1.0.0")]
1943 pub fn hard_link<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Result<()> {
1944 fs_imp::link(original.as_ref(), link.as_ref())
1947 /// Creates a new symbolic link on the filesystem.
1949 /// The `link` path will be a symbolic link pointing to the `original` path.
1950 /// On Windows, this will be a file symlink, not a directory symlink;
1951 /// for this reason, the platform-specific [`std::os::unix::fs::symlink`]
1952 /// and [`std::os::windows::fs::symlink_file`] or [`symlink_dir`] should be
1953 /// used instead to make the intent explicit.
1955 /// [`std::os::unix::fs::symlink`]: crate::os::unix::fs::symlink
1956 /// [`std::os::windows::fs::symlink_file`]: crate::os::windows::fs::symlink_file
1957 /// [`symlink_dir`]: crate::os::windows::fs::symlink_dir
1964 /// fn main() -> std::io::Result<()> {
1965 /// fs::soft_link("a.txt", "b.txt")?;
1969 #[stable(feature = "rust1", since = "1.0.0")]
1972 note = "replaced with std::os::unix::fs::symlink and \
1973 std::os::windows::fs::{symlink_file, symlink_dir}"
1975 pub fn soft_link<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Result<()> {
1976 fs_imp::symlink(original.as_ref(), link.as_ref())
1979 /// Reads a symbolic link, returning the file that the link points to.
1981 /// # Platform-specific behavior
1983 /// This function currently corresponds to the `readlink` function on Unix
1984 /// and the `CreateFile` function with `FILE_FLAG_OPEN_REPARSE_POINT` and
1985 /// `FILE_FLAG_BACKUP_SEMANTICS` flags on Windows.
1986 /// Note that, this [may change in the future][changes].
1988 /// [changes]: io#platform-specific-behavior
1992 /// This function will return an error in the following situations, but is not
1993 /// limited to just these cases:
1995 /// * `path` is not a symbolic link.
1996 /// * `path` does not exist.
2003 /// fn main() -> std::io::Result<()> {
2004 /// let path = fs::read_link("a.txt")?;
2008 #[stable(feature = "rust1", since = "1.0.0")]
2009 pub fn read_link<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
2010 fs_imp::readlink(path.as_ref())
2013 /// Returns the canonical, absolute form of a path with all intermediate
2014 /// components normalized and symbolic links resolved.
2016 /// # Platform-specific behavior
2018 /// This function currently corresponds to the `realpath` function on Unix
2019 /// and the `CreateFile` and `GetFinalPathNameByHandle` functions on Windows.
2020 /// Note that, this [may change in the future][changes].
2022 /// On Windows, this converts the path to use [extended length path][path]
2023 /// syntax, which allows your program to use longer path names, but means you
2024 /// can only join backslash-delimited paths to it, and it may be incompatible
2025 /// with other applications (if passed to the application on the command-line,
2026 /// or written to a file another application may read).
2028 /// [changes]: io#platform-specific-behavior
2029 /// [path]: https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file
2033 /// This function will return an error in the following situations, but is not
2034 /// limited to just these cases:
2036 /// * `path` does not exist.
2037 /// * A non-final component in path is not a directory.
2044 /// fn main() -> std::io::Result<()> {
2045 /// let path = fs::canonicalize("../a/../foo.txt")?;
2049 #[doc(alias = "realpath")]
2050 #[doc(alias = "GetFinalPathNameByHandle")]
2051 #[stable(feature = "fs_canonicalize", since = "1.5.0")]
2052 pub fn canonicalize<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
2053 fs_imp::canonicalize(path.as_ref())
2056 /// Creates a new, empty directory at the provided path
2058 /// # Platform-specific behavior
2060 /// This function currently corresponds to the `mkdir` function on Unix
2061 /// and the `CreateDirectory` function on Windows.
2062 /// Note that, this [may change in the future][changes].
2064 /// [changes]: io#platform-specific-behavior
2066 /// **NOTE**: If a parent of the given path doesn't exist, this function will
2067 /// return an error. To create a directory and all its missing parents at the
2068 /// same time, use the [`create_dir_all`] function.
2072 /// This function will return an error in the following situations, but is not
2073 /// limited to just these cases:
2075 /// * User lacks permissions to create directory at `path`.
2076 /// * A parent of the given path doesn't exist. (To create a directory and all
2077 /// its missing parents at the same time, use the [`create_dir_all`]
2079 /// * `path` already exists.
2086 /// fn main() -> std::io::Result<()> {
2087 /// fs::create_dir("/some/dir")?;
2091 #[doc(alias = "mkdir")]
2092 #[stable(feature = "rust1", since = "1.0.0")]
2093 pub fn create_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
2094 DirBuilder::new().create(path.as_ref())
2097 /// Recursively create a directory and all of its parent components if they
2100 /// # Platform-specific behavior
2102 /// This function currently corresponds to the `mkdir` function on Unix
2103 /// and the `CreateDirectory` function on Windows.
2104 /// Note that, this [may change in the future][changes].
2106 /// [changes]: io#platform-specific-behavior
2110 /// This function will return an error in the following situations, but is not
2111 /// limited to just these cases:
2113 /// * If any directory in the path specified by `path`
2114 /// does not already exist and it could not be created otherwise. The specific
2115 /// error conditions for when a directory is being created (after it is
2116 /// determined to not exist) are outlined by [`fs::create_dir`].
2118 /// Notable exception is made for situations where any of the directories
2119 /// specified in the `path` could not be created as it was being created concurrently.
2120 /// Such cases are considered to be successful. That is, calling `create_dir_all`
2121 /// concurrently from multiple threads or processes is guaranteed not to fail
2122 /// due to a race condition with itself.
2124 /// [`fs::create_dir`]: create_dir
2131 /// fn main() -> std::io::Result<()> {
2132 /// fs::create_dir_all("/some/dir")?;
2136 #[stable(feature = "rust1", since = "1.0.0")]
2137 pub fn create_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
2138 DirBuilder::new().recursive(true).create(path.as_ref())
2141 /// Removes an empty directory.
2143 /// # Platform-specific behavior
2145 /// This function currently corresponds to the `rmdir` function on Unix
2146 /// and the `RemoveDirectory` function on Windows.
2147 /// Note that, this [may change in the future][changes].
2149 /// [changes]: io#platform-specific-behavior
2153 /// This function will return an error in the following situations, but is not
2154 /// limited to just these cases:
2156 /// * `path` doesn't exist.
2157 /// * `path` isn't a directory.
2158 /// * The user lacks permissions to remove the directory at the provided `path`.
2159 /// * The directory isn't empty.
2166 /// fn main() -> std::io::Result<()> {
2167 /// fs::remove_dir("/some/dir")?;
2171 #[doc(alias = "rmdir")]
2172 #[stable(feature = "rust1", since = "1.0.0")]
2173 pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
2174 fs_imp::rmdir(path.as_ref())
2177 /// Removes a directory at this path, after removing all its contents. Use
2180 /// This function does **not** follow symbolic links and it will simply remove the
2181 /// symbolic link itself.
2183 /// # Platform-specific behavior
2185 /// This function currently corresponds to `openat`, `fdopendir`, `unlinkat` and `lstat` functions
2186 /// on Unix (except for macOS before version 10.10 and REDOX) and the `CreateFileW`,
2187 /// `GetFileInformationByHandleEx`, `SetFileInformationByHandle`, and `NtCreateFile` functions on
2188 /// Windows. Note that, this [may change in the future][changes].
2190 /// [changes]: io#platform-specific-behavior
2192 /// On macOS before version 10.10 and REDOX, as well as when running in Miri for any target, this
2193 /// function is not protected against time-of-check to time-of-use (TOCTOU) race conditions, and
2194 /// should not be used in security-sensitive code on those platforms. All other platforms are
2199 /// See [`fs::remove_file`] and [`fs::remove_dir`].
2201 /// [`fs::remove_file`]: remove_file
2202 /// [`fs::remove_dir`]: remove_dir
2209 /// fn main() -> std::io::Result<()> {
2210 /// fs::remove_dir_all("/some/dir")?;
2214 #[stable(feature = "rust1", since = "1.0.0")]
2215 pub fn remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
2216 fs_imp::remove_dir_all(path.as_ref())
2219 /// Returns an iterator over the entries within a directory.
2221 /// The iterator will yield instances of <code>[io::Result]<[DirEntry]></code>.
2222 /// New errors may be encountered after an iterator is initially constructed.
2223 /// Entries for the current and parent directories (typically `.` and `..`) are
2226 /// # Platform-specific behavior
2228 /// This function currently corresponds to the `opendir` function on Unix
2229 /// and the `FindFirstFile` function on Windows. Advancing the iterator
2230 /// currently corresponds to `readdir` on Unix and `FindNextFile` on Windows.
2231 /// Note that, this [may change in the future][changes].
2233 /// [changes]: io#platform-specific-behavior
2235 /// The order in which this iterator returns entries is platform and filesystem
2240 /// This function will return an error in the following situations, but is not
2241 /// limited to just these cases:
2243 /// * The provided `path` doesn't exist.
2244 /// * The process lacks permissions to view the contents.
2245 /// * The `path` points at a non-directory file.
2251 /// use std::fs::{self, DirEntry};
2252 /// use std::path::Path;
2254 /// // one possible implementation of walking a directory only visiting files
2255 /// fn visit_dirs(dir: &Path, cb: &dyn Fn(&DirEntry)) -> io::Result<()> {
2256 /// if dir.is_dir() {
2257 /// for entry in fs::read_dir(dir)? {
2258 /// let entry = entry?;
2259 /// let path = entry.path();
2260 /// if path.is_dir() {
2261 /// visit_dirs(&path, cb)?;
2272 /// use std::{fs, io};
2274 /// fn main() -> io::Result<()> {
2275 /// let mut entries = fs::read_dir(".")?
2276 /// .map(|res| res.map(|e| e.path()))
2277 /// .collect::<Result<Vec<_>, io::Error>>()?;
2279 /// // The order in which `read_dir` returns entries is not guaranteed. If reproducible
2280 /// // ordering is required the entries should be explicitly sorted.
2284 /// // The entries have now been sorted by their path.
2289 #[stable(feature = "rust1", since = "1.0.0")]
2290 pub fn read_dir<P: AsRef<Path>>(path: P) -> io::Result<ReadDir> {
2291 fs_imp::readdir(path.as_ref()).map(ReadDir)
2294 /// Changes the permissions found on a file or a directory.
2296 /// # Platform-specific behavior
2298 /// This function currently corresponds to the `chmod` function on Unix
2299 /// and the `SetFileAttributes` function on Windows.
2300 /// Note that, this [may change in the future][changes].
2302 /// [changes]: io#platform-specific-behavior
2306 /// This function will return an error in the following situations, but is not
2307 /// limited to just these cases:
2309 /// * `path` does not exist.
2310 /// * The user lacks the permission to change attributes of the file.
2317 /// fn main() -> std::io::Result<()> {
2318 /// let mut perms = fs::metadata("foo.txt")?.permissions();
2319 /// perms.set_readonly(true);
2320 /// fs::set_permissions("foo.txt", perms)?;
2324 #[stable(feature = "set_permissions", since = "1.1.0")]
2325 pub fn set_permissions<P: AsRef<Path>>(path: P, perm: Permissions) -> io::Result<()> {
2326 fs_imp::set_perm(path.as_ref(), perm.0)
2330 /// Creates a new set of options with default mode/security settings for all
2331 /// platforms and also non-recursive.
2336 /// use std::fs::DirBuilder;
2338 /// let builder = DirBuilder::new();
2340 #[stable(feature = "dir_builder", since = "1.6.0")]
2342 pub fn new() -> DirBuilder {
2343 DirBuilder { inner: fs_imp::DirBuilder::new(), recursive: false }
2346 /// Indicates that directories should be created recursively, creating all
2347 /// parent directories. Parents that do not exist are created with the same
2348 /// security and permissions settings.
2350 /// This option defaults to `false`.
2355 /// use std::fs::DirBuilder;
2357 /// let mut builder = DirBuilder::new();
2358 /// builder.recursive(true);
2360 #[stable(feature = "dir_builder", since = "1.6.0")]
2361 pub fn recursive(&mut self, recursive: bool) -> &mut Self {
2362 self.recursive = recursive;
2366 /// Creates the specified directory with the options configured in this
2369 /// It is considered an error if the directory already exists unless
2370 /// recursive mode is enabled.
2375 /// use std::fs::{self, DirBuilder};
2377 /// let path = "/tmp/foo/bar/baz";
2378 /// DirBuilder::new()
2379 /// .recursive(true)
2380 /// .create(path).unwrap();
2382 /// assert!(fs::metadata(path).unwrap().is_dir());
2384 #[stable(feature = "dir_builder", since = "1.6.0")]
2385 pub fn create<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
2386 self._create(path.as_ref())
2389 fn _create(&self, path: &Path) -> io::Result<()> {
2390 if self.recursive { self.create_dir_all(path) } else { self.inner.mkdir(path) }
2393 fn create_dir_all(&self, path: &Path) -> io::Result<()> {
2394 if path == Path::new("") {
2398 match self.inner.mkdir(path) {
2399 Ok(()) => return Ok(()),
2400 Err(ref e) if e.kind() == io::ErrorKind::NotFound => {}
2401 Err(_) if path.is_dir() => return Ok(()),
2402 Err(e) => return Err(e),
2404 match path.parent() {
2405 Some(p) => self.create_dir_all(p)?,
2407 return Err(io::const_io_error!(
2408 io::ErrorKind::Uncategorized,
2409 "failed to create whole tree",
2413 match self.inner.mkdir(path) {
2415 Err(_) if path.is_dir() => Ok(()),
2421 impl AsInnerMut<fs_imp::DirBuilder> for DirBuilder {
2422 fn as_inner_mut(&mut self) -> &mut fs_imp::DirBuilder {
2427 /// Returns `Ok(true)` if the path points at an existing entity.
2429 /// This function will traverse symbolic links to query information about the
2430 /// destination file. In case of broken symbolic links this will return `Ok(false)`.
2432 /// As opposed to the [`Path::exists`] method, this one doesn't silently ignore errors
2433 /// unrelated to the path not existing. (E.g. it will return `Err(_)` in case of permission
2434 /// denied on some of the parent directories.)
2436 /// Note that while this avoids some pitfalls of the `exists()` method, it still can not
2437 /// prevent time-of-check to time-of-use (TOCTOU) bugs. You should only use it in scenarios
2438 /// where those bugs are not an issue.
2443 /// #![feature(fs_try_exists)]
2446 /// assert!(!fs::try_exists("does_not_exist.txt").expect("Can't check existence of file does_not_exist.txt"));
2447 /// assert!(fs::try_exists("/root/secret_file.txt").is_err());
2450 /// [`Path::exists`]: crate::path::Path::exists
2451 // FIXME: stabilization should modify documentation of `exists()` to recommend this method
2453 #[unstable(feature = "fs_try_exists", issue = "83186")]
2455 pub fn try_exists<P: AsRef<Path>>(path: P) -> io::Result<bool> {
2456 fs_imp::try_exists(path.as_ref())