1 //! Filesystem manipulation operations.
2 //!
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`.
7
8 #![deny(unsafe_op_in_unsafe_fn)]
9
10 use crate::std::ffi::OsString;
11 use crate::std::fmt;
12 use crate::std::io::{self, BorrowedCursor, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write};
13 use crate::std::path::{Path, PathBuf};
14 use crate::std::sealed::Sealed;
15 use crate::std::sync::Arc;
16 use crate::std::sys::fs as fs_imp;
17 use crate::std::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
18 use crate::std::time::SystemTime;
19
20 /// An object providing access to an open file on the filesystem.
21 ///
22 /// An instance of a `File` can be read and/or written depending on what options
23 /// it was opened with. Files also implement [`Seek`] to alter the logical cursor
24 /// that the file contains internally.
25 ///
26 /// Files are automatically closed when they go out of scope. Errors detected
27 /// on closing are ignored by the implementation of `Drop`. Use the method
28 /// [`sync_all`] if these errors must be manually handled.
29 ///
30 /// # Examples
31 ///
32 /// Creates a new file and write bytes to it (you can also use [`write()`]):
33 ///
34 /// ```no_run
35 /// use std::fs::File;
36 /// use std::io::prelude::*;
37 ///
38 /// fn main() -> std::io::Result<()> {
39 /// let mut file = File::create("foo.txt")?;
40 /// file.write_all(b"Hello, world!")?;
41 /// Ok(())
42 /// }
43 /// ```
44 ///
45 /// Read the contents of a file into a [`String`] (you can also use [`read`]):
46 ///
47 /// ```no_run
48 /// use std::fs::File;
49 /// use std::io::prelude::*;
50 ///
51 /// fn main() -> std::io::Result<()> {
52 /// let mut file = File::open("foo.txt")?;
53 /// let mut contents = String::new();
54 /// file.read_to_string(&mut contents)?;
55 /// assert_eq!(contents, "Hello, world!");
56 /// Ok(())
57 /// }
58 /// ```
59 ///
60 /// It can be more efficient to read the contents of a file with a buffered
61 /// [`Read`]er. This can be accomplished with [`BufReader<R>`]:
62 ///
63 /// ```no_run
64 /// use std::fs::File;
65 /// use std::io::BufReader;
66 /// use std::io::prelude::*;
67 ///
68 /// fn main() -> std::io::Result<()> {
69 /// let file = File::open("foo.txt")?;
70 /// let mut buf_reader = BufReader::new(file);
71 /// let mut contents = String::new();
72 /// buf_reader.read_to_string(&mut contents)?;
73 /// assert_eq!(contents, "Hello, world!");
74 /// Ok(())
75 /// }
76 /// ```
77 ///
78 /// Note that, although read and write methods require a `&mut File`, because
79 /// of the interfaces for [`Read`] and [`Write`], the holder of a `&File` can
80 /// still modify the file, either through methods that take `&File` or by
81 /// retrieving the underlying OS object and modifying the file that way.
82 /// Additionally, many operating systems allow concurrent modification of files
83 /// by different processes. Avoid assuming that holding a `&File` means that the
84 /// file will not change.
85 ///
86 /// # Platform-specific behavior
87 ///
88 /// On Windows, the implementation of [`Read`] and [`Write`] traits for `File`
89 /// perform synchronous I/O operations. Therefore the underlying file must not
90 /// have been opened for asynchronous I/O (e.g. by using `FILE_FLAG_OVERLAPPED`).
91 ///
92 /// [`BufReader<R>`]: io::BufReader
93 /// [`sync_all`]: File::sync_all
94 #[cfg_attr(not(test), rustc_diagnostic_item = "File")]
95 pub struct File {
96 inner: fs_imp::File,
97 }
98
99 /// Metadata information about a file.
100 ///
101 /// This structure is returned from the [`metadata`] or
102 /// [`symlink_metadata`] function or method and represents known
103 /// metadata about a file such as its permissions, size, modification
104 /// times, etc.
105 #[derive(Clone)]
106 pub struct Metadata(fs_imp::FileAttr);
107
108 /// Iterator over the entries in a directory.
109 ///
110 /// This iterator is returned from the [`read_dir`] function of this module and
111 /// will yield instances of <code>[io::Result]<[DirEntry]></code>. Through a [`DirEntry`]
112 /// information like the entry's path and possibly other metadata can be
113 /// learned.
114 ///
115 /// The order in which this iterator returns entries is platform and filesystem
116 /// dependent.
117 ///
118 /// # Errors
119 ///
120 /// This [`io::Result`] will be an [`Err`] if there's some sort of intermittent
121 /// IO error during iteration.
122 #[derive(Debug)]
123 pub struct ReadDir(fs_imp::ReadDir);
124
125 /// Entries returned by the [`ReadDir`] iterator.
126 ///
127 /// An instance of `DirEntry` represents an entry inside of a directory on the
128 /// filesystem. Each entry can be inspected via methods to learn about the full
129 /// path or possibly other metadata through per-platform extension traits.
130 ///
131 /// # Platform-specific behavior
132 ///
133 /// On Unix, the `DirEntry` struct contains an internal reference to the open
134 /// directory. Holding `DirEntry` objects will consume a file handle even
135 /// after the `ReadDir` iterator is dropped.
136 ///
137 /// Note that this [may change in the future][changes].
138 ///
139 /// [changes]: io#platform-specific-behavior
140 pub struct DirEntry(fs_imp::DirEntry);
141
142 /// Options and flags which can be used to configure how a file is opened.
143 ///
144 /// This builder exposes the ability to configure how a [`File`] is opened and
145 /// what operations are permitted on the open file. The [`File::open`] and
146 /// [`File::create`] methods are aliases for commonly used options using this
147 /// builder.
148 ///
149 /// Generally speaking, when using `OpenOptions`, you'll first call
150 /// [`OpenOptions::new`], then chain calls to methods to set each option, then
151 /// call [`OpenOptions::open`], passing the path of the file you're trying to
152 /// open. This will give you a [`io::Result`] with a [`File`] inside that you
153 /// can further operate on.
154 ///
155 /// # Examples
156 ///
157 /// Opening a file to read:
158 ///
159 /// ```no_run
160 /// use std::fs::OpenOptions;
161 ///
162 /// let file = OpenOptions::new().read(true).open("foo.txt");
163 /// ```
164 ///
165 /// Opening a file for both reading and writing, as well as creating it if it
166 /// doesn't exist:
167 ///
168 /// ```no_run
169 /// use std::fs::OpenOptions;
170 ///
171 /// let file = OpenOptions::new()
172 /// .read(true)
173 /// .write(true)
174 /// .create(true)
175 /// .open("foo.txt");
176 /// ```
177 #[derive(Clone, Debug)]
178 pub struct OpenOptions(fs_imp::OpenOptions);
179
180 /// Representation of the various timestamps on a file.
181 #[derive(Copy, Clone, Debug, Default)]
182 pub struct FileTimes(fs_imp::FileTimes);
183
184 /// Representation of the various permissions on a file.
185 ///
186 /// This module only currently provides one bit of information,
187 /// [`Permissions::readonly`], which is exposed on all currently supported
188 /// platforms. Unix-specific functionality, such as mode bits, is available
189 /// through the [`PermissionsExt`] trait.
190 ///
191 /// [`PermissionsExt`]: crate::std::os::unix::fs::PermissionsExt
192 #[derive(Clone, PartialEq, Eq, Debug)]
193 pub struct Permissions(fs_imp::FilePermissions);
194
195 /// A structure representing a type of file with accessors for each file type.
196 /// It is returned by [`Metadata::file_type`] method.
197 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
198 #[cfg_attr(not(test), rustc_diagnostic_item = "FileType")]
199 pub struct FileType(fs_imp::FileType);
200
201 /// A builder used to create directories in various manners.
202 ///
203 /// This builder also supports platform-specific options.
204 #[cfg_attr(not(test), rustc_diagnostic_item = "DirBuilder")]
205 #[derive(Debug)]
206 pub struct DirBuilder {
207 inner: fs_imp::DirBuilder,
208 recursive: bool,
209 }
210
211 /// Read the entire contents of a file into a bytes vector.
212 ///
213 /// This is a convenience function for using [`File::open`] and [`read_to_end`]
214 /// with fewer imports and without an intermediate variable.
215 ///
216 /// [`read_to_end`]: Read::read_to_end
217 ///
218 /// # Errors
219 ///
220 /// This function will return an error if `path` does not already exist.
221 /// Other errors may also be returned according to [`OpenOptions::open`].
222 ///
223 /// While reading from the file, this function handles [`io::ErrorKind::Interrupted`]
224 /// with automatic retries. See [io::Read] documentation for details.
225 ///
226 /// # Examples
227 ///
228 /// ```no_run
229 /// use std::fs;
230 /// use std::net::SocketAddr;
231 ///
232 /// fn main() -> Result<(), Box<dyn std::error::Error + 'static>> {
233 /// let foo: SocketAddr = String::from_utf8_lossy(&fs::read("address.txt")?).parse()?;
234 /// Ok(())
235 /// }
236 /// ```
read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>>237 pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
238 fn inner(path: &Path) -> io::Result<Vec<u8>> {
239 let mut file = File::open(path)?;
240 let size = file.metadata().map(|m| m.len() as usize).ok();
241 let mut bytes = Vec::with_capacity(size.unwrap_or(0));
242 io::default_read_to_end(&mut file, &mut bytes, size)?;
243 Ok(bytes)
244 }
245 inner(path.as_ref())
246 }
247
248 /// Read the entire contents of a file into a string.
249 ///
250 /// This is a convenience function for using [`File::open`] and [`read_to_string`]
251 /// with fewer imports and without an intermediate variable.
252 ///
253 /// [`read_to_string`]: Read::read_to_string
254 ///
255 /// # Errors
256 ///
257 /// This function will return an error if `path` does not already exist.
258 /// Other errors may also be returned according to [`OpenOptions::open`].
259 ///
260 /// If the contents of the file are not valid UTF-8, then an error will also be
261 /// returned.
262 ///
263 /// While reading from the file, this function handles [`io::ErrorKind::Interrupted`]
264 /// with automatic retries. See [io::Read] documentation for details.
265 ///
266 /// # Examples
267 ///
268 /// ```no_run
269 /// use std::fs;
270 /// use std::net::SocketAddr;
271 /// use std::error::Error;
272 ///
273 /// fn main() -> Result<(), Box<dyn Error>> {
274 /// let foo: SocketAddr = fs::read_to_string("address.txt")?.parse()?;
275 /// Ok(())
276 /// }
277 /// ```
read_to_string<P: AsRef<Path>>(path: P) -> io::Result<String>278 pub fn read_to_string<P: AsRef<Path>>(path: P) -> io::Result<String> {
279 fn inner(path: &Path) -> io::Result<String> {
280 let mut file = File::open(path)?;
281 let size = file.metadata().map(|m| m.len() as usize).ok();
282 let mut string = String::with_capacity(size.unwrap_or(0));
283 io::default_read_to_string(&mut file, &mut string, size)?;
284 Ok(string)
285 }
286 inner(path.as_ref())
287 }
288
289 /// Write a slice as the entire contents of a file.
290 ///
291 /// This function will create a file if it does not exist,
292 /// and will entirely replace its contents if it does.
293 ///
294 /// Depending on the platform, this function may fail if the
295 /// full directory path does not exist.
296 ///
297 /// This is a convenience function for using [`File::create`] and [`write_all`]
298 /// with fewer imports.
299 ///
300 /// [`write_all`]: Write::write_all
301 ///
302 /// # Examples
303 ///
304 /// ```no_run
305 /// use std::fs;
306 ///
307 /// fn main() -> std::io::Result<()> {
308 /// fs::write("foo.txt", b"Lorem ipsum")?;
309 /// fs::write("bar.txt", "dolor sit")?;
310 /// Ok(())
311 /// }
312 /// ```
write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result<()>313 pub fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result<()> {
314 fn inner(path: &Path, contents: &[u8]) -> io::Result<()> {
315 File::create(path)?.write_all(contents)
316 }
317 inner(path.as_ref(), contents.as_ref())
318 }
319
320 impl File {
321 /// Attempts to open a file in read-only mode.
322 ///
323 /// See the [`OpenOptions::open`] method for more details.
324 ///
325 /// If you only need to read the entire file contents,
326 /// consider [`std::fs::read()`][self::read] or
327 /// [`std::fs::read_to_string()`][self::read_to_string] instead.
328 ///
329 /// # Errors
330 ///
331 /// This function will return an error if `path` does not already exist.
332 /// Other errors may also be returned according to [`OpenOptions::open`].
333 ///
334 /// # Examples
335 ///
336 /// ```no_run
337 /// use std::fs::File;
338 /// use std::io::Read;
339 ///
340 /// fn main() -> std::io::Result<()> {
341 /// let mut f = File::open("foo.txt")?;
342 /// let mut data = vec![];
343 /// f.read_to_end(&mut data)?;
344 /// Ok(())
345 /// }
346 /// ```
open<P: AsRef<Path>>(path: P) -> io::Result<File>347 pub fn open<P: AsRef<Path>>(path: P) -> io::Result<File> {
348 OpenOptions::new().read(true).open(path.as_ref())
349 }
350
351 /// Opens a file in write-only mode.
352 ///
353 /// This function will create a file if it does not exist,
354 /// and will truncate it if it does.
355 ///
356 /// Depending on the platform, this function may fail if the
357 /// full directory path does not exist.
358 /// See the [`OpenOptions::open`] function for more details.
359 ///
360 /// See also [`std::fs::write()`][self::write] for a simple function to
361 /// create a file with a given data.
362 ///
363 /// # Examples
364 ///
365 /// ```no_run
366 /// use std::fs::File;
367 /// use std::io::Write;
368 ///
369 /// fn main() -> std::io::Result<()> {
370 /// let mut f = File::create("foo.txt")?;
371 /// f.write_all(&1234_u32.to_be_bytes())?;
372 /// Ok(())
373 /// }
374 /// ```
create<P: AsRef<Path>>(path: P) -> io::Result<File>375 pub fn create<P: AsRef<Path>>(path: P) -> io::Result<File> {
376 OpenOptions::new()
377 .write(true)
378 .create(true)
379 .truncate(true)
380 .open(path.as_ref())
381 }
382
383 /// Creates a new file in read-write mode; error if the file exists.
384 ///
385 /// This function will create a file if it does not exist, or return an error if it does. This
386 /// way, if the call succeeds, the file returned is guaranteed to be new.
387 ///
388 /// This option is useful because it is atomic. Otherwise between checking whether a file
389 /// exists and creating a new one, the file may have been created by another process (a TOCTOU
390 /// race condition / attack).
391 ///
392 /// This can also be written using
393 /// `File::options().read(true).write(true).create_new(true).open(...)`.
394 ///
395 /// # Examples
396 ///
397 /// ```no_run
398 /// #![feature(file_create_new)]
399 ///
400 /// use std::fs::File;
401 /// use std::io::Write;
402 ///
403 /// fn main() -> std::io::Result<()> {
404 /// let mut f = File::create_new("foo.txt")?;
405 /// f.write_all("Hello, world!".as_bytes())?;
406 /// Ok(())
407 /// }
408 /// ```
create_new<P: AsRef<Path>>(path: P) -> io::Result<File>409 pub fn create_new<P: AsRef<Path>>(path: P) -> io::Result<File> {
410 OpenOptions::new()
411 .read(true)
412 .write(true)
413 .create_new(true)
414 .open(path.as_ref())
415 }
416
417 /// Returns a new OpenOptions object.
418 ///
419 /// This function returns a new OpenOptions object that you can use to
420 /// open or create a file with specific options if `open()` or `create()`
421 /// are not appropriate.
422 ///
423 /// It is equivalent to `OpenOptions::new()`, but allows you to write more
424 /// readable code. Instead of
425 /// `OpenOptions::new().append(true).open("example.log")`,
426 /// you can write `File::options().append(true).open("example.log")`. This
427 /// also avoids the need to import `OpenOptions`.
428 ///
429 /// See the [`OpenOptions::new`] function for more details.
430 ///
431 /// # Examples
432 ///
433 /// ```no_run
434 /// use std::fs::File;
435 /// use std::io::Write;
436 ///
437 /// fn main() -> std::io::Result<()> {
438 /// let mut f = File::options().append(true).open("example.log")?;
439 /// writeln!(&mut f, "new line")?;
440 /// Ok(())
441 /// }
442 /// ```
443 #[must_use]
options() -> OpenOptions444 pub fn options() -> OpenOptions {
445 OpenOptions::new()
446 }
447
448 /// Attempts to sync all OS-internal metadata to disk.
449 ///
450 /// This function will attempt to ensure that all in-memory data reaches the
451 /// filesystem before returning.
452 ///
453 /// This can be used to handle errors that would otherwise only be caught
454 /// when the `File` is closed. Dropping a file will ignore errors in
455 /// synchronizing this in-memory data.
456 ///
457 /// # Examples
458 ///
459 /// ```no_run
460 /// use std::fs::File;
461 /// use std::io::prelude::*;
462 ///
463 /// fn main() -> std::io::Result<()> {
464 /// let mut f = File::create("foo.txt")?;
465 /// f.write_all(b"Hello, world!")?;
466 ///
467 /// f.sync_all()?;
468 /// Ok(())
469 /// }
470 /// ```
sync_all(&self) -> io::Result<()>471 pub fn sync_all(&self) -> io::Result<()> {
472 self.inner.fsync()
473 }
474
475 /// This function is similar to [`sync_all`], except that it might not
476 /// synchronize file metadata to the filesystem.
477 ///
478 /// This is intended for use cases that must synchronize content, but don't
479 /// need the metadata on disk. The goal of this method is to reduce disk
480 /// operations.
481 ///
482 /// Note that some platforms may simply implement this in terms of
483 /// [`sync_all`].
484 ///
485 /// [`sync_all`]: File::sync_all
486 ///
487 /// # Examples
488 ///
489 /// ```no_run
490 /// use std::fs::File;
491 /// use std::io::prelude::*;
492 ///
493 /// fn main() -> std::io::Result<()> {
494 /// let mut f = File::create("foo.txt")?;
495 /// f.write_all(b"Hello, world!")?;
496 ///
497 /// f.sync_data()?;
498 /// Ok(())
499 /// }
500 /// ```
sync_data(&self) -> io::Result<()>501 pub fn sync_data(&self) -> io::Result<()> {
502 self.inner.datasync()
503 }
504
505 /// Truncates or extends the underlying file, updating the size of
506 /// this file to become `size`.
507 ///
508 /// If the `size` is less than the current file's size, then the file will
509 /// be shrunk. If it is greater than the current file's size, then the file
510 /// will be extended to `size` and have all of the intermediate data filled
511 /// in with 0s.
512 ///
513 /// The file's cursor isn't changed. In particular, if the cursor was at the
514 /// end and the file is shrunk using this operation, the cursor will now be
515 /// past the end.
516 ///
517 /// # Errors
518 ///
519 /// This function will return an error if the file is not opened for writing.
520 /// Also, [`std::io::ErrorKind::InvalidInput`](crate::std::io::ErrorKind::InvalidInput)
521 /// will be returned if the desired length would cause an overflow due to
522 /// the implementation specifics.
523 ///
524 /// # Examples
525 ///
526 /// ```no_run
527 /// use std::fs::File;
528 ///
529 /// fn main() -> std::io::Result<()> {
530 /// let mut f = File::create("foo.txt")?;
531 /// f.set_len(10)?;
532 /// Ok(())
533 /// }
534 /// ```
535 ///
536 /// Note that this method alters the content of the underlying file, even
537 /// though it takes `&self` rather than `&mut self`.
set_len(&self, size: u64) -> io::Result<()>538 pub fn set_len(&self, size: u64) -> io::Result<()> {
539 self.inner.truncate(size)
540 }
541
542 /// Queries metadata about the underlying file.
543 ///
544 /// # Examples
545 ///
546 /// ```no_run
547 /// use std::fs::File;
548 ///
549 /// fn main() -> std::io::Result<()> {
550 /// let mut f = File::open("foo.txt")?;
551 /// let metadata = f.metadata()?;
552 /// Ok(())
553 /// }
554 /// ```
metadata(&self) -> io::Result<Metadata>555 pub fn metadata(&self) -> io::Result<Metadata> {
556 self.inner.file_attr().map(Metadata)
557 }
558
559 /// Creates a new `File` instance that shares the same underlying file handle
560 /// as the existing `File` instance. Reads, writes, and seeks will affect
561 /// both `File` instances simultaneously.
562 ///
563 /// # Examples
564 ///
565 /// Creates two handles for a file named `foo.txt`:
566 ///
567 /// ```no_run
568 /// use std::fs::File;
569 ///
570 /// fn main() -> std::io::Result<()> {
571 /// let mut file = File::open("foo.txt")?;
572 /// let file_copy = file.try_clone()?;
573 /// Ok(())
574 /// }
575 /// ```
576 ///
577 /// Assuming there’s a file named `foo.txt` with contents `abcdef\n`, create
578 /// two handles, seek one of them, and read the remaining bytes from the
579 /// other handle:
580 ///
581 /// ```no_run
582 /// use std::fs::File;
583 /// use std::io::SeekFrom;
584 /// use std::io::prelude::*;
585 ///
586 /// fn main() -> std::io::Result<()> {
587 /// let mut file = File::open("foo.txt")?;
588 /// let mut file_copy = file.try_clone()?;
589 ///
590 /// file.seek(SeekFrom::Start(3))?;
591 ///
592 /// let mut contents = vec![];
593 /// file_copy.read_to_end(&mut contents)?;
594 /// assert_eq!(contents, b"def\n");
595 /// Ok(())
596 /// }
597 /// ```
try_clone(&self) -> io::Result<File>598 pub fn try_clone(&self) -> io::Result<File> {
599 Ok(File {
600 inner: self.inner.duplicate()?,
601 })
602 }
603
604 /// Changes the permissions on the underlying file.
605 ///
606 /// # Platform-specific behavior
607 ///
608 /// This function currently corresponds to the `fchmod` function on Unix and
609 /// the `SetFileInformationByHandle` function on Windows. Note that, this
610 /// [may change in the future][changes].
611 ///
612 /// [changes]: io#platform-specific-behavior
613 ///
614 /// # Errors
615 ///
616 /// This function will return an error if the user lacks permission change
617 /// attributes on the underlying file. It may also return an error in other
618 /// os-specific unspecified cases.
619 ///
620 /// # Examples
621 ///
622 /// ```no_run
623 /// fn main() -> std::io::Result<()> {
624 /// use std::fs::File;
625 ///
626 /// let file = File::open("foo.txt")?;
627 /// let mut perms = file.metadata()?.permissions();
628 /// perms.set_readonly(true);
629 /// file.set_permissions(perms)?;
630 /// Ok(())
631 /// }
632 /// ```
633 ///
634 /// Note that this method alters the permissions of the underlying file,
635 /// even though it takes `&self` rather than `&mut self`.
set_permissions(&self, perm: Permissions) -> io::Result<()>636 pub fn set_permissions(&self, perm: Permissions) -> io::Result<()> {
637 self.inner.set_permissions(perm.0)
638 }
639
640 /// Changes the timestamps of the underlying file.
641 ///
642 /// # Platform-specific behavior
643 ///
644 /// This function currently corresponds to the `futimens` function on Unix (falling back to
645 /// `futimes` on macOS before 10.13) and the `SetFileTime` function on Windows. Note that this
646 /// [may change in the future][changes].
647 ///
648 /// [changes]: io#platform-specific-behavior
649 ///
650 /// # Errors
651 ///
652 /// This function will return an error if the user lacks permission to change timestamps on the
653 /// underlying file. It may also return an error in other os-specific unspecified cases.
654 ///
655 /// This function may return an error if the operating system lacks support to change one or
656 /// more of the timestamps set in the `FileTimes` structure.
657 ///
658 /// # Examples
659 ///
660 /// ```no_run
661 /// #![feature(file_set_times)]
662 ///
663 /// fn main() -> std::io::Result<()> {
664 /// use std::fs::{self, File, FileTimes};
665 ///
666 /// let src = fs::metadata("src")?;
667 /// let dest = File::options().write(true).open("dest")?;
668 /// let times = FileTimes::new()
669 /// .set_accessed(src.accessed()?)
670 /// .set_modified(src.modified()?);
671 /// dest.set_times(times)?;
672 /// Ok(())
673 /// }
674 /// ```
675 #[doc(alias = "futimens")]
676 #[doc(alias = "futimes")]
677 #[doc(alias = "SetFileTime")]
set_times(&self, times: FileTimes) -> io::Result<()>678 pub fn set_times(&self, times: FileTimes) -> io::Result<()> {
679 self.inner.set_times(times.0)
680 }
681
682 /// Changes the modification time of the underlying file.
683 ///
684 /// This is an alias for `set_times(FileTimes::new().set_modified(time))`.
685 #[inline]
set_modified(&self, time: SystemTime) -> io::Result<()>686 pub fn set_modified(&self, time: SystemTime) -> io::Result<()> {
687 self.set_times(FileTimes::new().set_modified(time))
688 }
689 }
690
691 // In addition to the `impl`s here, `File` also has `impl`s for
692 // `AsFd`/`From<OwnedFd>`/`Into<OwnedFd>` and
693 // `AsRawFd`/`IntoRawFd`/`FromRawFd`, on Unix and WASI, and
694 // `AsHandle`/`From<OwnedHandle>`/`Into<OwnedHandle>` and
695 // `AsRawHandle`/`IntoRawHandle`/`FromRawHandle` on Windows.
696
697 impl AsInner<fs_imp::File> for File {
698 #[inline]
as_inner(&self) -> &fs_imp::File699 fn as_inner(&self) -> &fs_imp::File {
700 &self.inner
701 }
702 }
703 impl FromInner<fs_imp::File> for File {
from_inner(f: fs_imp::File) -> File704 fn from_inner(f: fs_imp::File) -> File {
705 File { inner: f }
706 }
707 }
708 impl IntoInner<fs_imp::File> for File {
into_inner(self) -> fs_imp::File709 fn into_inner(self) -> fs_imp::File {
710 self.inner
711 }
712 }
713
714 impl fmt::Debug for File {
fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result715 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
716 self.inner.fmt(f)
717 }
718 }
719
720 /// Indicates how much extra capacity is needed to read the rest of the file.
buffer_capacity_required(mut file: &File) -> Option<usize>721 fn buffer_capacity_required(mut file: &File) -> Option<usize> {
722 let size = file.metadata().map(|m| m.len()).ok()?;
723 let pos = file.stream_position().ok()?;
724 // Don't worry about `usize` overflow because reading will fail regardless
725 // in that case.
726 Some(size.saturating_sub(pos) as usize)
727 }
728
729 impl Read for &File {
730 #[inline]
read(&mut self, buf: &mut [u8]) -> io::Result<usize>731 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
732 self.inner.read(buf)
733 }
734
735 #[inline]
read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize>736 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
737 self.inner.read_vectored(bufs)
738 }
739
740 #[inline]
read_buf(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()>741 fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
742 self.inner.read_buf(cursor)
743 }
744
745 #[inline]
is_read_vectored(&self) -> bool746 fn is_read_vectored(&self) -> bool {
747 self.inner.is_read_vectored()
748 }
749
750 // Reserves space in the buffer based on the file size when available.
read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize>751 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
752 let size = buffer_capacity_required(self);
753 buf.reserve(size.unwrap_or(0));
754 io::default_read_to_end(self, buf, size)
755 }
756
757 // Reserves space in the buffer based on the file size when available.
read_to_string(&mut self, buf: &mut String) -> io::Result<usize>758 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
759 let size = buffer_capacity_required(self);
760 buf.reserve(size.unwrap_or(0));
761 io::default_read_to_string(self, buf, size)
762 }
763 }
764 impl Write for &File {
write(&mut self, buf: &[u8]) -> io::Result<usize>765 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
766 self.inner.write(buf)
767 }
768
write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize>769 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
770 self.inner.write_vectored(bufs)
771 }
772
773 #[inline]
is_write_vectored(&self) -> bool774 fn is_write_vectored(&self) -> bool {
775 self.inner.is_write_vectored()
776 }
777
778 #[inline]
flush(&mut self) -> io::Result<()>779 fn flush(&mut self) -> io::Result<()> {
780 self.inner.flush()
781 }
782 }
783 impl Seek for &File {
seek(&mut self, pos: SeekFrom) -> io::Result<u64>784 fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
785 self.inner.seek(pos)
786 }
787 }
788
789 impl Read for File {
read(&mut self, buf: &mut [u8]) -> io::Result<usize>790 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
791 (&*self).read(buf)
792 }
read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize>793 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
794 (&*self).read_vectored(bufs)
795 }
read_buf(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()>796 fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
797 (&*self).read_buf(cursor)
798 }
799 #[inline]
is_read_vectored(&self) -> bool800 fn is_read_vectored(&self) -> bool {
801 (&&*self).is_read_vectored()
802 }
read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize>803 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
804 (&*self).read_to_end(buf)
805 }
read_to_string(&mut self, buf: &mut String) -> io::Result<usize>806 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
807 (&*self).read_to_string(buf)
808 }
809 }
810 impl Write for File {
write(&mut self, buf: &[u8]) -> io::Result<usize>811 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
812 (&*self).write(buf)
813 }
write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize>814 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
815 (&*self).write_vectored(bufs)
816 }
817 #[inline]
is_write_vectored(&self) -> bool818 fn is_write_vectored(&self) -> bool {
819 (&&*self).is_write_vectored()
820 }
821 #[inline]
flush(&mut self) -> io::Result<()>822 fn flush(&mut self) -> io::Result<()> {
823 (&*self).flush()
824 }
825 }
826 impl Seek for File {
seek(&mut self, pos: SeekFrom) -> io::Result<u64>827 fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
828 (&*self).seek(pos)
829 }
830 }
831
832 impl Read for Arc<File> {
read(&mut self, buf: &mut [u8]) -> io::Result<usize>833 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
834 (&**self).read(buf)
835 }
read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize>836 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
837 (&**self).read_vectored(bufs)
838 }
read_buf(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()>839 fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
840 (&**self).read_buf(cursor)
841 }
842 #[inline]
is_read_vectored(&self) -> bool843 fn is_read_vectored(&self) -> bool {
844 (&**self).is_read_vectored()
845 }
read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize>846 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
847 (&**self).read_to_end(buf)
848 }
read_to_string(&mut self, buf: &mut String) -> io::Result<usize>849 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
850 (&**self).read_to_string(buf)
851 }
852 }
853 impl Write for Arc<File> {
write(&mut self, buf: &[u8]) -> io::Result<usize>854 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
855 (&**self).write(buf)
856 }
write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize>857 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
858 (&**self).write_vectored(bufs)
859 }
860 #[inline]
is_write_vectored(&self) -> bool861 fn is_write_vectored(&self) -> bool {
862 (&**self).is_write_vectored()
863 }
864 #[inline]
flush(&mut self) -> io::Result<()>865 fn flush(&mut self) -> io::Result<()> {
866 (&**self).flush()
867 }
868 }
869 impl Seek for Arc<File> {
seek(&mut self, pos: SeekFrom) -> io::Result<u64>870 fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
871 (&**self).seek(pos)
872 }
873 }
874
875 impl OpenOptions {
876 /// Creates a blank new set of options ready for configuration.
877 ///
878 /// All options are initially set to `false`.
879 ///
880 /// # Examples
881 ///
882 /// ```no_run
883 /// use std::fs::OpenOptions;
884 ///
885 /// let mut options = OpenOptions::new();
886 /// let file = options.read(true).open("foo.txt");
887 /// ```
888 #[must_use]
new() -> Self889 pub fn new() -> Self {
890 OpenOptions(fs_imp::OpenOptions::new())
891 }
892
893 /// Sets the option for read access.
894 ///
895 /// This option, when true, will indicate that the file should be
896 /// `read`-able if opened.
897 ///
898 /// # Examples
899 ///
900 /// ```no_run
901 /// use std::fs::OpenOptions;
902 ///
903 /// let file = OpenOptions::new().read(true).open("foo.txt");
904 /// ```
read(&mut self, read: bool) -> &mut Self905 pub fn read(&mut self, read: bool) -> &mut Self {
906 self.0.read(read);
907 self
908 }
909
910 /// Sets the option for write access.
911 ///
912 /// This option, when true, will indicate that the file should be
913 /// `write`-able if opened.
914 ///
915 /// If the file already exists, any write calls on it will overwrite its
916 /// contents, without truncating it.
917 ///
918 /// # Examples
919 ///
920 /// ```no_run
921 /// use std::fs::OpenOptions;
922 ///
923 /// let file = OpenOptions::new().write(true).open("foo.txt");
924 /// ```
write(&mut self, write: bool) -> &mut Self925 pub fn write(&mut self, write: bool) -> &mut Self {
926 self.0.write(write);
927 self
928 }
929
930 /// Sets the option for the append mode.
931 ///
932 /// This option, when true, means that writes will append to a file instead
933 /// of overwriting previous contents.
934 /// Note that setting `.write(true).append(true)` has the same effect as
935 /// setting only `.append(true)`.
936 ///
937 /// For most filesystems, the operating system guarantees that all writes are
938 /// atomic: no writes get mangled because another process writes at the same
939 /// time.
940 ///
941 /// One maybe obvious note when using append-mode: make sure that all data
942 /// that belongs together is written to the file in one operation. This
943 /// can be done by concatenating strings before passing them to [`write()`],
944 /// or using a buffered writer (with a buffer of adequate size),
945 /// and calling [`flush()`] when the message is complete.
946 ///
947 /// If a file is opened with both read and append access, beware that after
948 /// opening, and after every write, the position for reading may be set at the
949 /// end of the file. So, before writing, save the current position (using
950 /// <code>[seek]\([SeekFrom]::[Current]\(0))</code>), and restore it before the next read.
951 ///
952 /// ## Note
953 ///
954 /// This function doesn't create the file if it doesn't exist. Use the
955 /// [`OpenOptions::create`] method to do so.
956 ///
957 /// [`write()`]: Write::write "io::Write::write"
958 /// [`flush()`]: Write::flush "io::Write::flush"
959 /// [seek]: Seek::seek "io::Seek::seek"
960 /// [Current]: SeekFrom::Current "io::SeekFrom::Current"
961 ///
962 /// # Examples
963 ///
964 /// ```no_run
965 /// use std::fs::OpenOptions;
966 ///
967 /// let file = OpenOptions::new().append(true).open("foo.txt");
968 /// ```
append(&mut self, append: bool) -> &mut Self969 pub fn append(&mut self, append: bool) -> &mut Self {
970 self.0.append(append);
971 self
972 }
973
974 /// Sets the option for truncating a previous file.
975 ///
976 /// If a file is successfully opened with this option set it will truncate
977 /// the file to 0 length if it already exists.
978 ///
979 /// The file must be opened with write access for truncate to work.
980 ///
981 /// # Examples
982 ///
983 /// ```no_run
984 /// use std::fs::OpenOptions;
985 ///
986 /// let file = OpenOptions::new().write(true).truncate(true).open("foo.txt");
987 /// ```
truncate(&mut self, truncate: bool) -> &mut Self988 pub fn truncate(&mut self, truncate: bool) -> &mut Self {
989 self.0.truncate(truncate);
990 self
991 }
992
993 /// Sets the option to create a new file, or open it if it already exists.
994 ///
995 /// In order for the file to be created, [`OpenOptions::write`] or
996 /// [`OpenOptions::append`] access must be used.
997 ///
998 /// See also [`std::fs::write()`][self::write] for a simple function to
999 /// create a file with a given data.
1000 ///
1001 /// # Examples
1002 ///
1003 /// ```no_run
1004 /// use std::fs::OpenOptions;
1005 ///
1006 /// let file = OpenOptions::new().write(true).create(true).open("foo.txt");
1007 /// ```
create(&mut self, create: bool) -> &mut Self1008 pub fn create(&mut self, create: bool) -> &mut Self {
1009 self.0.create(create);
1010 self
1011 }
1012
1013 /// Sets the option to create a new file, failing if it already exists.
1014 ///
1015 /// No file is allowed to exist at the target location, also no (dangling) symlink. In this
1016 /// way, if the call succeeds, the file returned is guaranteed to be new.
1017 ///
1018 /// This option is useful because it is atomic. Otherwise between checking
1019 /// whether a file exists and creating a new one, the file may have been
1020 /// created by another process (a TOCTOU race condition / attack).
1021 ///
1022 /// If `.create_new(true)` is set, [`.create()`] and [`.truncate()`] are
1023 /// ignored.
1024 ///
1025 /// The file must be opened with write or append access in order to create
1026 /// a new file.
1027 ///
1028 /// [`.create()`]: OpenOptions::create
1029 /// [`.truncate()`]: OpenOptions::truncate
1030 ///
1031 /// # Examples
1032 ///
1033 /// ```no_run
1034 /// use std::fs::OpenOptions;
1035 ///
1036 /// let file = OpenOptions::new().write(true)
1037 /// .create_new(true)
1038 /// .open("foo.txt");
1039 /// ```
create_new(&mut self, create_new: bool) -> &mut Self1040 pub fn create_new(&mut self, create_new: bool) -> &mut Self {
1041 self.0.create_new(create_new);
1042 self
1043 }
1044
1045 /// Opens a file at `path` with the options specified by `self`.
1046 ///
1047 /// # Errors
1048 ///
1049 /// This function will return an error under a number of different
1050 /// circumstances. Some of these error conditions are listed here, together
1051 /// with their [`io::ErrorKind`]. The mapping to [`io::ErrorKind`]s is not
1052 /// part of the compatibility contract of the function.
1053 ///
1054 /// * [`NotFound`]: The specified file does not exist and neither `create`
1055 /// or `create_new` is set.
1056 /// * [`NotFound`]: One of the directory components of the file path does
1057 /// not exist.
1058 /// * [`PermissionDenied`]: The user lacks permission to get the specified
1059 /// access rights for the file.
1060 /// * [`PermissionDenied`]: The user lacks permission to open one of the
1061 /// directory components of the specified path.
1062 /// * [`AlreadyExists`]: `create_new` was specified and the file already
1063 /// exists.
1064 /// * [`InvalidInput`]: Invalid combinations of open options (truncate
1065 /// without write access, no access mode set, etc.).
1066 ///
1067 /// The following errors don't match any existing [`io::ErrorKind`] at the moment:
1068 /// * One of the directory components of the specified file path
1069 /// was not, in fact, a directory.
1070 /// * Filesystem-level errors: full disk, write permission
1071 /// requested on a read-only file system, exceeded disk quota, too many
1072 /// open files, too long filename, too many symbolic links in the
1073 /// specified path (Unix-like systems only), etc.
1074 ///
1075 /// # Examples
1076 ///
1077 /// ```no_run
1078 /// use std::fs::OpenOptions;
1079 ///
1080 /// let file = OpenOptions::new().read(true).open("foo.txt");
1081 /// ```
1082 ///
1083 /// [`AlreadyExists`]: io::ErrorKind::AlreadyExists
1084 /// [`InvalidInput`]: io::ErrorKind::InvalidInput
1085 /// [`NotFound`]: io::ErrorKind::NotFound
1086 /// [`PermissionDenied`]: io::ErrorKind::PermissionDenied
open<P: AsRef<Path>>(&self, path: P) -> io::Result<File>1087 pub fn open<P: AsRef<Path>>(&self, path: P) -> io::Result<File> {
1088 self._open(path.as_ref())
1089 }
1090
_open(&self, path: &Path) -> io::Result<File>1091 fn _open(&self, path: &Path) -> io::Result<File> {
1092 fs_imp::File::open(path, &self.0).map(|inner| File { inner })
1093 }
1094 }
1095
1096 impl AsInner<fs_imp::OpenOptions> for OpenOptions {
1097 #[inline]
as_inner(&self) -> &fs_imp::OpenOptions1098 fn as_inner(&self) -> &fs_imp::OpenOptions {
1099 &self.0
1100 }
1101 }
1102
1103 impl AsInnerMut<fs_imp::OpenOptions> for OpenOptions {
1104 #[inline]
as_inner_mut(&mut self) -> &mut fs_imp::OpenOptions1105 fn as_inner_mut(&mut self) -> &mut fs_imp::OpenOptions {
1106 &mut self.0
1107 }
1108 }
1109
1110 impl Metadata {
1111 /// Returns the file type for this metadata.
1112 ///
1113 /// # Examples
1114 ///
1115 /// ```no_run
1116 /// fn main() -> std::io::Result<()> {
1117 /// use std::fs;
1118 ///
1119 /// let metadata = fs::metadata("foo.txt")?;
1120 ///
1121 /// println!("{:?}", metadata.file_type());
1122 /// Ok(())
1123 /// }
1124 /// ```
1125 #[must_use]
file_type(&self) -> FileType1126 pub fn file_type(&self) -> FileType {
1127 FileType(self.0.file_type())
1128 }
1129
1130 /// Returns `true` if this metadata is for a directory. The
1131 /// result is mutually exclusive to the result of
1132 /// [`Metadata::is_file`], and will be false for symlink metadata
1133 /// obtained from [`symlink_metadata`].
1134 ///
1135 /// # Examples
1136 ///
1137 /// ```no_run
1138 /// fn main() -> std::io::Result<()> {
1139 /// use std::fs;
1140 ///
1141 /// let metadata = fs::metadata("foo.txt")?;
1142 ///
1143 /// assert!(!metadata.is_dir());
1144 /// Ok(())
1145 /// }
1146 /// ```
1147 #[must_use]
is_dir(&self) -> bool1148 pub fn is_dir(&self) -> bool {
1149 self.file_type().is_dir()
1150 }
1151
1152 /// Returns `true` if this metadata is for a regular file. The
1153 /// result is mutually exclusive to the result of
1154 /// [`Metadata::is_dir`], and will be false for symlink metadata
1155 /// obtained from [`symlink_metadata`].
1156 ///
1157 /// When the goal is simply to read from (or write to) the source, the most
1158 /// reliable way to test the source can be read (or written to) is to open
1159 /// it. Only using `is_file` can break workflows like `diff <( prog_a )` on
1160 /// a Unix-like system for example. See [`File::open`] or
1161 /// [`OpenOptions::open`] for more information.
1162 ///
1163 /// # Examples
1164 ///
1165 /// ```no_run
1166 /// use std::fs;
1167 ///
1168 /// fn main() -> std::io::Result<()> {
1169 /// let metadata = fs::metadata("foo.txt")?;
1170 ///
1171 /// assert!(metadata.is_file());
1172 /// Ok(())
1173 /// }
1174 /// ```
1175 #[must_use]
is_file(&self) -> bool1176 pub fn is_file(&self) -> bool {
1177 self.file_type().is_file()
1178 }
1179
1180 /// Returns `true` if this metadata is for a symbolic link.
1181 ///
1182 /// # Examples
1183 ///
1184 #[cfg_attr(unix, doc = "```no_run")]
1185 #[cfg_attr(not(unix), doc = "```ignore")]
1186 /// use std::fs;
1187 /// use std::path::Path;
1188 /// use std::os::unix::fs::symlink;
1189 ///
1190 /// fn main() -> std::io::Result<()> {
1191 /// let link_path = Path::new("link");
1192 /// symlink("/origin_does_not_exist/", link_path)?;
1193 ///
1194 /// let metadata = fs::symlink_metadata(link_path)?;
1195 ///
1196 /// assert!(metadata.is_symlink());
1197 /// Ok(())
1198 /// }
1199 /// ```
1200 #[must_use]
is_symlink(&self) -> bool1201 pub fn is_symlink(&self) -> bool {
1202 self.file_type().is_symlink()
1203 }
1204
1205 /// Returns the size of the file, in bytes, this metadata is for.
1206 ///
1207 /// # Examples
1208 ///
1209 /// ```no_run
1210 /// use std::fs;
1211 ///
1212 /// fn main() -> std::io::Result<()> {
1213 /// let metadata = fs::metadata("foo.txt")?;
1214 ///
1215 /// assert_eq!(0, metadata.len());
1216 /// Ok(())
1217 /// }
1218 /// ```
1219 #[must_use]
len(&self) -> u641220 pub fn len(&self) -> u64 {
1221 self.0.size()
1222 }
1223
1224 /// Returns the permissions of the file this metadata is for.
1225 ///
1226 /// # Examples
1227 ///
1228 /// ```no_run
1229 /// use std::fs;
1230 ///
1231 /// fn main() -> std::io::Result<()> {
1232 /// let metadata = fs::metadata("foo.txt")?;
1233 ///
1234 /// assert!(!metadata.permissions().readonly());
1235 /// Ok(())
1236 /// }
1237 /// ```
1238 #[must_use]
permissions(&self) -> Permissions1239 pub fn permissions(&self) -> Permissions {
1240 Permissions(self.0.perm())
1241 }
1242
1243 /// Returns the last modification time listed in this metadata.
1244 ///
1245 /// The returned value corresponds to the `mtime` field of `stat` on Unix
1246 /// platforms and the `ftLastWriteTime` field on Windows platforms.
1247 ///
1248 /// # Errors
1249 ///
1250 /// This field might not be available on all platforms, and will return an
1251 /// `Err` on platforms where it is not available.
1252 ///
1253 /// # Examples
1254 ///
1255 /// ```no_run
1256 /// use std::fs;
1257 ///
1258 /// fn main() -> std::io::Result<()> {
1259 /// let metadata = fs::metadata("foo.txt")?;
1260 ///
1261 /// if let Ok(time) = metadata.modified() {
1262 /// println!("{time:?}");
1263 /// } else {
1264 /// println!("Not supported on this platform");
1265 /// }
1266 /// Ok(())
1267 /// }
1268 /// ```
modified(&self) -> io::Result<SystemTime>1269 pub fn modified(&self) -> io::Result<SystemTime> {
1270 self.0.modified().map(FromInner::from_inner)
1271 }
1272
1273 /// Returns the last access time of this metadata.
1274 ///
1275 /// The returned value corresponds to the `atime` field of `stat` on Unix
1276 /// platforms and the `ftLastAccessTime` field on Windows platforms.
1277 ///
1278 /// Note that not all platforms will keep this field update in a file's
1279 /// metadata, for example Windows has an option to disable updating this
1280 /// time when files are accessed and Linux similarly has `noatime`.
1281 ///
1282 /// # Errors
1283 ///
1284 /// This field might not be available on all platforms, and will return an
1285 /// `Err` on platforms where it is not available.
1286 ///
1287 /// # Examples
1288 ///
1289 /// ```no_run
1290 /// use std::fs;
1291 ///
1292 /// fn main() -> std::io::Result<()> {
1293 /// let metadata = fs::metadata("foo.txt")?;
1294 ///
1295 /// if let Ok(time) = metadata.accessed() {
1296 /// println!("{time:?}");
1297 /// } else {
1298 /// println!("Not supported on this platform");
1299 /// }
1300 /// Ok(())
1301 /// }
1302 /// ```
accessed(&self) -> io::Result<SystemTime>1303 pub fn accessed(&self) -> io::Result<SystemTime> {
1304 self.0.accessed().map(FromInner::from_inner)
1305 }
1306
1307 /// Returns the creation time listed in this metadata.
1308 ///
1309 /// The returned value corresponds to the `btime` field of `statx` on
1310 /// Linux kernel starting from to 4.11, the `birthtime` field of `stat` on other
1311 /// Unix platforms, and the `ftCreationTime` field on Windows platforms.
1312 ///
1313 /// # Errors
1314 ///
1315 /// This field might not be available on all platforms, and will return an
1316 /// `Err` on platforms or filesystems where it is not available.
1317 ///
1318 /// # Examples
1319 ///
1320 /// ```no_run
1321 /// use std::fs;
1322 ///
1323 /// fn main() -> std::io::Result<()> {
1324 /// let metadata = fs::metadata("foo.txt")?;
1325 ///
1326 /// if let Ok(time) = metadata.created() {
1327 /// println!("{time:?}");
1328 /// } else {
1329 /// println!("Not supported on this platform or filesystem");
1330 /// }
1331 /// Ok(())
1332 /// }
1333 /// ```
created(&self) -> io::Result<SystemTime>1334 pub fn created(&self) -> io::Result<SystemTime> {
1335 self.0.created().map(FromInner::from_inner)
1336 }
1337 }
1338
1339 impl fmt::Debug for Metadata {
fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result1340 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1341 f.debug_struct("Metadata")
1342 .field("file_type", &self.file_type())
1343 .field("is_dir", &self.is_dir())
1344 .field("is_file", &self.is_file())
1345 .field("permissions", &self.permissions())
1346 .field("modified", &self.modified())
1347 .field("accessed", &self.accessed())
1348 .field("created", &self.created())
1349 .finish_non_exhaustive()
1350 }
1351 }
1352
1353 impl AsInner<fs_imp::FileAttr> for Metadata {
1354 #[inline]
as_inner(&self) -> &fs_imp::FileAttr1355 fn as_inner(&self) -> &fs_imp::FileAttr {
1356 &self.0
1357 }
1358 }
1359
1360 impl FromInner<fs_imp::FileAttr> for Metadata {
from_inner(attr: fs_imp::FileAttr) -> Metadata1361 fn from_inner(attr: fs_imp::FileAttr) -> Metadata {
1362 Metadata(attr)
1363 }
1364 }
1365
1366 impl FileTimes {
1367 /// Create a new `FileTimes` with no times set.
1368 ///
1369 /// Using the resulting `FileTimes` in [`File::set_times`] will not modify any timestamps.
new() -> Self1370 pub fn new() -> Self {
1371 Self::default()
1372 }
1373
1374 /// Set the last access time of a file.
set_accessed(mut self, t: SystemTime) -> Self1375 pub fn set_accessed(mut self, t: SystemTime) -> Self {
1376 self.0.set_accessed(t.into_inner());
1377 self
1378 }
1379
1380 /// Set the last modified time of a file.
set_modified(mut self, t: SystemTime) -> Self1381 pub fn set_modified(mut self, t: SystemTime) -> Self {
1382 self.0.set_modified(t.into_inner());
1383 self
1384 }
1385 }
1386
1387 impl AsInnerMut<fs_imp::FileTimes> for FileTimes {
as_inner_mut(&mut self) -> &mut fs_imp::FileTimes1388 fn as_inner_mut(&mut self) -> &mut fs_imp::FileTimes {
1389 &mut self.0
1390 }
1391 }
1392
1393 // For implementing OS extension traits in `std::os`
1394 impl Sealed for FileTimes {}
1395
1396 impl Permissions {
1397 /// Returns `true` if these permissions describe a readonly (unwritable) file.
1398 ///
1399 /// # Note
1400 ///
1401 /// This function does not take Access Control Lists (ACLs) or Unix group
1402 /// membership into account.
1403 ///
1404 /// # Windows
1405 ///
1406 /// On Windows this returns [`FILE_ATTRIBUTE_READONLY`](https://docs.microsoft.com/en-us/windows/win32/fileio/file-attribute-constants).
1407 /// If `FILE_ATTRIBUTE_READONLY` is set then writes to the file will fail
1408 /// but the user may still have permission to change this flag. If
1409 /// `FILE_ATTRIBUTE_READONLY` is *not* set then writes may still fail due
1410 /// to lack of write permission.
1411 /// The behavior of this attribute for directories depends on the Windows
1412 /// version.
1413 ///
1414 /// # Unix (including macOS)
1415 ///
1416 /// On Unix-based platforms this checks if *any* of the owner, group or others
1417 /// write permission bits are set. It does not check if the current
1418 /// user is in the file's assigned group. It also does not check ACLs.
1419 /// Therefore even if this returns true you may not be able to write to the
1420 /// file, and vice versa. The [`PermissionsExt`] trait gives direct access
1421 /// to the permission bits but also does not read ACLs. If you need to
1422 /// accurately know whether or not a file is writable use the `access()`
1423 /// function from libc.
1424 ///
1425 /// [`PermissionsExt`]: crate::std::os::unix::fs::PermissionsExt
1426 ///
1427 /// # Examples
1428 ///
1429 /// ```no_run
1430 /// use std::fs::File;
1431 ///
1432 /// fn main() -> std::io::Result<()> {
1433 /// let mut f = File::create("foo.txt")?;
1434 /// let metadata = f.metadata()?;
1435 ///
1436 /// assert_eq!(false, metadata.permissions().readonly());
1437 /// Ok(())
1438 /// }
1439 /// ```
1440 #[must_use = "call `set_readonly` to modify the readonly flag"]
readonly(&self) -> bool1441 pub fn readonly(&self) -> bool {
1442 self.0.readonly()
1443 }
1444
1445 /// Modifies the readonly flag for this set of permissions. If the
1446 /// `readonly` argument is `true`, using the resulting `Permission` will
1447 /// update file permissions to forbid writing. Conversely, if it's `false`,
1448 /// using the resulting `Permission` will update file permissions to allow
1449 /// writing.
1450 ///
1451 /// This operation does **not** modify the files attributes. This only
1452 /// changes the in-memory value of these attributes for this `Permissions`
1453 /// instance. To modify the files attributes use the [`set_permissions`]
1454 /// function which commits these attribute changes to the file.
1455 ///
1456 /// # Note
1457 ///
1458 /// `set_readonly(false)` makes the file *world-writable* on Unix.
1459 /// You can use the [`PermissionsExt`] trait on Unix to avoid this issue.
1460 ///
1461 /// It also does not take Access Control Lists (ACLs) or Unix group
1462 /// membership into account.
1463 ///
1464 /// # Windows
1465 ///
1466 /// On Windows this sets or clears [`FILE_ATTRIBUTE_READONLY`](https://docs.microsoft.com/en-us/windows/win32/fileio/file-attribute-constants).
1467 /// If `FILE_ATTRIBUTE_READONLY` is set then writes to the file will fail
1468 /// but the user may still have permission to change this flag. If
1469 /// `FILE_ATTRIBUTE_READONLY` is *not* set then the write may still fail if
1470 /// the user does not have permission to write to the file.
1471 ///
1472 /// In Windows 7 and earlier this attribute prevents deleting empty
1473 /// directories. It does not prevent modifying the directory contents.
1474 /// On later versions of Windows this attribute is ignored for directories.
1475 ///
1476 /// # Unix (including macOS)
1477 ///
1478 /// On Unix-based platforms this sets or clears the write access bit for
1479 /// the owner, group *and* others, equivalent to `chmod a+w <file>`
1480 /// or `chmod a-w <file>` respectively. The latter will grant write access
1481 /// to all users! You can use the [`PermissionsExt`] trait on Unix
1482 /// to avoid this issue.
1483 ///
1484 /// [`PermissionsExt`]: crate::std::os::unix::fs::PermissionsExt
1485 ///
1486 /// # Examples
1487 ///
1488 /// ```no_run
1489 /// use std::fs::File;
1490 ///
1491 /// fn main() -> std::io::Result<()> {
1492 /// let f = File::create("foo.txt")?;
1493 /// let metadata = f.metadata()?;
1494 /// let mut permissions = metadata.permissions();
1495 ///
1496 /// permissions.set_readonly(true);
1497 ///
1498 /// // filesystem doesn't change, only the in memory state of the
1499 /// // readonly permission
1500 /// assert_eq!(false, metadata.permissions().readonly());
1501 ///
1502 /// // just this particular `permissions`.
1503 /// assert_eq!(true, permissions.readonly());
1504 /// Ok(())
1505 /// }
1506 /// ```
set_readonly(&mut self, readonly: bool)1507 pub fn set_readonly(&mut self, readonly: bool) {
1508 self.0.set_readonly(readonly)
1509 }
1510 }
1511
1512 impl FileType {
1513 /// Tests whether this file type represents a directory. The
1514 /// result is mutually exclusive to the results of
1515 /// [`is_file`] and [`is_symlink`]; only zero or one of these
1516 /// tests may pass.
1517 ///
1518 /// [`is_file`]: FileType::is_file
1519 /// [`is_symlink`]: FileType::is_symlink
1520 ///
1521 /// # Examples
1522 ///
1523 /// ```no_run
1524 /// fn main() -> std::io::Result<()> {
1525 /// use std::fs;
1526 ///
1527 /// let metadata = fs::metadata("foo.txt")?;
1528 /// let file_type = metadata.file_type();
1529 ///
1530 /// assert_eq!(file_type.is_dir(), false);
1531 /// Ok(())
1532 /// }
1533 /// ```
1534 #[must_use]
is_dir(&self) -> bool1535 pub fn is_dir(&self) -> bool {
1536 self.0.is_dir()
1537 }
1538
1539 /// Tests whether this file type represents a regular file.
1540 /// The result is mutually exclusive to the results of
1541 /// [`is_dir`] and [`is_symlink`]; only zero or one of these
1542 /// tests may pass.
1543 ///
1544 /// When the goal is simply to read from (or write to) the source, the most
1545 /// reliable way to test the source can be read (or written to) is to open
1546 /// it. Only using `is_file` can break workflows like `diff <( prog_a )` on
1547 /// a Unix-like system for example. See [`File::open`] or
1548 /// [`OpenOptions::open`] for more information.
1549 ///
1550 /// [`is_dir`]: FileType::is_dir
1551 /// [`is_symlink`]: FileType::is_symlink
1552 ///
1553 /// # Examples
1554 ///
1555 /// ```no_run
1556 /// fn main() -> std::io::Result<()> {
1557 /// use std::fs;
1558 ///
1559 /// let metadata = fs::metadata("foo.txt")?;
1560 /// let file_type = metadata.file_type();
1561 ///
1562 /// assert_eq!(file_type.is_file(), true);
1563 /// Ok(())
1564 /// }
1565 /// ```
1566 #[must_use]
is_file(&self) -> bool1567 pub fn is_file(&self) -> bool {
1568 self.0.is_file()
1569 }
1570
1571 /// Tests whether this file type represents a symbolic link.
1572 /// The result is mutually exclusive to the results of
1573 /// [`is_dir`] and [`is_file`]; only zero or one of these
1574 /// tests may pass.
1575 ///
1576 /// The underlying [`Metadata`] struct needs to be retrieved
1577 /// with the [`fs::symlink_metadata`] function and not the
1578 /// [`fs::metadata`] function. The [`fs::metadata`] function
1579 /// follows symbolic links, so [`is_symlink`] would always
1580 /// return `false` for the target file.
1581 ///
1582 /// [`fs::metadata`]: metadata
1583 /// [`fs::symlink_metadata`]: symlink_metadata
1584 /// [`is_dir`]: FileType::is_dir
1585 /// [`is_file`]: FileType::is_file
1586 /// [`is_symlink`]: FileType::is_symlink
1587 ///
1588 /// # Examples
1589 ///
1590 /// ```no_run
1591 /// use std::fs;
1592 ///
1593 /// fn main() -> std::io::Result<()> {
1594 /// let metadata = fs::symlink_metadata("foo.txt")?;
1595 /// let file_type = metadata.file_type();
1596 ///
1597 /// assert_eq!(file_type.is_symlink(), false);
1598 /// Ok(())
1599 /// }
1600 /// ```
1601 #[must_use]
is_symlink(&self) -> bool1602 pub fn is_symlink(&self) -> bool {
1603 self.0.is_symlink()
1604 }
1605 }
1606
1607 impl AsInner<fs_imp::FileType> for FileType {
1608 #[inline]
as_inner(&self) -> &fs_imp::FileType1609 fn as_inner(&self) -> &fs_imp::FileType {
1610 &self.0
1611 }
1612 }
1613
1614 impl FromInner<fs_imp::FilePermissions> for Permissions {
from_inner(f: fs_imp::FilePermissions) -> Permissions1615 fn from_inner(f: fs_imp::FilePermissions) -> Permissions {
1616 Permissions(f)
1617 }
1618 }
1619
1620 impl AsInner<fs_imp::FilePermissions> for Permissions {
1621 #[inline]
as_inner(&self) -> &fs_imp::FilePermissions1622 fn as_inner(&self) -> &fs_imp::FilePermissions {
1623 &self.0
1624 }
1625 }
1626
1627 impl Iterator for ReadDir {
1628 type Item = io::Result<DirEntry>;
1629
next(&mut self) -> Option<io::Result<DirEntry>>1630 fn next(&mut self) -> Option<io::Result<DirEntry>> {
1631 self.0.next().map(|entry| entry.map(DirEntry))
1632 }
1633 }
1634
1635 impl DirEntry {
1636 /// Returns the full path to the file that this entry represents.
1637 ///
1638 /// The full path is created by joining the original path to `read_dir`
1639 /// with the filename of this entry.
1640 ///
1641 /// # Examples
1642 ///
1643 /// ```no_run
1644 /// use std::fs;
1645 ///
1646 /// fn main() -> std::io::Result<()> {
1647 /// for entry in fs::read_dir(".")? {
1648 /// let dir = entry?;
1649 /// println!("{:?}", dir.path());
1650 /// }
1651 /// Ok(())
1652 /// }
1653 /// ```
1654 ///
1655 /// This prints output like:
1656 ///
1657 /// ```text
1658 /// "./whatever.txt"
1659 /// "./foo.html"
1660 /// "./hello_world.rs"
1661 /// ```
1662 ///
1663 /// The exact text, of course, depends on what files you have in `.`.
1664 #[must_use]
path(&self) -> PathBuf1665 pub fn path(&self) -> PathBuf {
1666 self.0.path()
1667 }
1668
1669 /// Returns the metadata for the file that this entry points at.
1670 ///
1671 /// This function will not traverse symlinks if this entry points at a
1672 /// symlink. To traverse symlinks use [`fs::metadata`] or [`fs::File::metadata`].
1673 ///
1674 /// [`fs::metadata`]: metadata
1675 /// [`fs::File::metadata`]: File::metadata
1676 ///
1677 /// # Platform-specific behavior
1678 ///
1679 /// On Windows this function is cheap to call (no extra system calls
1680 /// needed), but on Unix platforms this function is the equivalent of
1681 /// calling `symlink_metadata` on the path.
1682 ///
1683 /// # Examples
1684 ///
1685 /// ```
1686 /// use std::fs;
1687 ///
1688 /// if let Ok(entries) = fs::read_dir(".") {
1689 /// for entry in entries {
1690 /// if let Ok(entry) = entry {
1691 /// // Here, `entry` is a `DirEntry`.
1692 /// if let Ok(metadata) = entry.metadata() {
1693 /// // Now let's show our entry's permissions!
1694 /// println!("{:?}: {:?}", entry.path(), metadata.permissions());
1695 /// } else {
1696 /// println!("Couldn't get metadata for {:?}", entry.path());
1697 /// }
1698 /// }
1699 /// }
1700 /// }
1701 /// ```
metadata(&self) -> io::Result<Metadata>1702 pub fn metadata(&self) -> io::Result<Metadata> {
1703 self.0.metadata().map(Metadata)
1704 }
1705
1706 /// Returns the file type for the file that this entry points at.
1707 ///
1708 /// This function will not traverse symlinks if this entry points at a
1709 /// symlink.
1710 ///
1711 /// # Platform-specific behavior
1712 ///
1713 /// On Windows and most Unix platforms this function is free (no extra
1714 /// system calls needed), but some Unix platforms may require the equivalent
1715 /// call to `symlink_metadata` to learn about the target file type.
1716 ///
1717 /// # Examples
1718 ///
1719 /// ```
1720 /// use std::fs;
1721 ///
1722 /// if let Ok(entries) = fs::read_dir(".") {
1723 /// for entry in entries {
1724 /// if let Ok(entry) = entry {
1725 /// // Here, `entry` is a `DirEntry`.
1726 /// if let Ok(file_type) = entry.file_type() {
1727 /// // Now let's show our entry's file type!
1728 /// println!("{:?}: {:?}", entry.path(), file_type);
1729 /// } else {
1730 /// println!("Couldn't get file type for {:?}", entry.path());
1731 /// }
1732 /// }
1733 /// }
1734 /// }
1735 /// ```
file_type(&self) -> io::Result<FileType>1736 pub fn file_type(&self) -> io::Result<FileType> {
1737 self.0.file_type().map(FileType)
1738 }
1739
1740 /// Returns the file name of this directory entry without any
1741 /// leading path component(s).
1742 ///
1743 /// As an example,
1744 /// the output of the function will result in "foo" for all the following paths:
1745 /// - "./foo"
1746 /// - "/the/foo"
1747 /// - "../../foo"
1748 ///
1749 /// # Examples
1750 ///
1751 /// ```
1752 /// use std::fs;
1753 ///
1754 /// if let Ok(entries) = fs::read_dir(".") {
1755 /// for entry in entries {
1756 /// if let Ok(entry) = entry {
1757 /// // Here, `entry` is a `DirEntry`.
1758 /// println!("{:?}", entry.file_name());
1759 /// }
1760 /// }
1761 /// }
1762 /// ```
1763 #[must_use]
file_name(&self) -> OsString1764 pub fn file_name(&self) -> OsString {
1765 self.0.file_name()
1766 }
1767 }
1768
1769 impl fmt::Debug for DirEntry {
fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result1770 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1771 f.debug_tuple("DirEntry").field(&self.path()).finish()
1772 }
1773 }
1774
1775 impl AsInner<fs_imp::DirEntry> for DirEntry {
1776 #[inline]
as_inner(&self) -> &fs_imp::DirEntry1777 fn as_inner(&self) -> &fs_imp::DirEntry {
1778 &self.0
1779 }
1780 }
1781
1782 /// Removes a file from the filesystem.
1783 ///
1784 /// Note that there is no
1785 /// guarantee that the file is immediately deleted (e.g., depending on
1786 /// platform, other open file descriptors may prevent immediate removal).
1787 ///
1788 /// # Platform-specific behavior
1789 ///
1790 /// This function currently corresponds to the `unlink` function on Unix
1791 /// and the `DeleteFile` function on Windows.
1792 /// Note that, this [may change in the future][changes].
1793 ///
1794 /// [changes]: io#platform-specific-behavior
1795 ///
1796 /// # Errors
1797 ///
1798 /// This function will return an error in the following situations, but is not
1799 /// limited to just these cases:
1800 ///
1801 /// * `path` points to a directory.
1802 /// * The file doesn't exist.
1803 /// * The user lacks permissions to remove the file.
1804 ///
1805 /// # Examples
1806 ///
1807 /// ```no_run
1808 /// use std::fs;
1809 ///
1810 /// fn main() -> std::io::Result<()> {
1811 /// fs::remove_file("a.txt")?;
1812 /// Ok(())
1813 /// }
1814 /// ```
remove_file<P: AsRef<Path>>(path: P) -> io::Result<()>1815 pub fn remove_file<P: AsRef<Path>>(path: P) -> io::Result<()> {
1816 fs_imp::unlink(path.as_ref())
1817 }
1818
1819 /// Given a path, query the file system to get information about a file,
1820 /// directory, etc.
1821 ///
1822 /// This function will traverse symbolic links to query information about the
1823 /// destination file.
1824 ///
1825 /// # Platform-specific behavior
1826 ///
1827 /// This function currently corresponds to the `stat` function on Unix
1828 /// and the `GetFileInformationByHandle` function on Windows.
1829 /// Note that, this [may change in the future][changes].
1830 ///
1831 /// [changes]: io#platform-specific-behavior
1832 ///
1833 /// # Errors
1834 ///
1835 /// This function will return an error in the following situations, but is not
1836 /// limited to just these cases:
1837 ///
1838 /// * The user lacks permissions to perform `metadata` call on `path`.
1839 /// * `path` does not exist.
1840 ///
1841 /// # Examples
1842 ///
1843 /// ```rust,no_run
1844 /// use std::fs;
1845 ///
1846 /// fn main() -> std::io::Result<()> {
1847 /// let attr = fs::metadata("/some/file/path.txt")?;
1848 /// // inspect attr ...
1849 /// Ok(())
1850 /// }
1851 /// ```
metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata>1852 pub fn metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
1853 fs_imp::stat(path.as_ref()).map(Metadata)
1854 }
1855
1856 /// Query the metadata about a file without following symlinks.
1857 ///
1858 /// # Platform-specific behavior
1859 ///
1860 /// This function currently corresponds to the `lstat` function on Unix
1861 /// and the `GetFileInformationByHandle` function on Windows.
1862 /// Note that, this [may change in the future][changes].
1863 ///
1864 /// [changes]: io#platform-specific-behavior
1865 ///
1866 /// # Errors
1867 ///
1868 /// This function will return an error in the following situations, but is not
1869 /// limited to just these cases:
1870 ///
1871 /// * The user lacks permissions to perform `metadata` call on `path`.
1872 /// * `path` does not exist.
1873 ///
1874 /// # Examples
1875 ///
1876 /// ```rust,no_run
1877 /// use std::fs;
1878 ///
1879 /// fn main() -> std::io::Result<()> {
1880 /// let attr = fs::symlink_metadata("/some/file/path.txt")?;
1881 /// // inspect attr ...
1882 /// Ok(())
1883 /// }
1884 /// ```
symlink_metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata>1885 pub fn symlink_metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
1886 fs_imp::lstat(path.as_ref()).map(Metadata)
1887 }
1888
1889 /// Rename a file or directory to a new name, replacing the original file if
1890 /// `to` already exists.
1891 ///
1892 /// This will not work if the new name is on a different mount point.
1893 ///
1894 /// # Platform-specific behavior
1895 ///
1896 /// This function currently corresponds to the `rename` function on Unix
1897 /// and the `MoveFileEx` function with the `MOVEFILE_REPLACE_EXISTING` flag on Windows.
1898 ///
1899 /// Because of this, the behavior when both `from` and `to` exist differs. On
1900 /// Unix, if `from` is a directory, `to` must also be an (empty) directory. If
1901 /// `from` is not a directory, `to` must also be not a directory. In contrast,
1902 /// on Windows, `from` can be anything, but `to` must *not* be a directory.
1903 ///
1904 /// Note that, this [may change in the future][changes].
1905 ///
1906 /// [changes]: io#platform-specific-behavior
1907 ///
1908 /// # Errors
1909 ///
1910 /// This function will return an error in the following situations, but is not
1911 /// limited to just these cases:
1912 ///
1913 /// * `from` does not exist.
1914 /// * The user lacks permissions to view contents.
1915 /// * `from` and `to` are on separate filesystems.
1916 ///
1917 /// # Examples
1918 ///
1919 /// ```no_run
1920 /// use std::fs;
1921 ///
1922 /// fn main() -> std::io::Result<()> {
1923 /// fs::rename("a.txt", "b.txt")?; // Rename a.txt to b.txt
1924 /// Ok(())
1925 /// }
1926 /// ```
rename<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()>1927 pub fn rename<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()> {
1928 fs_imp::rename(from.as_ref(), to.as_ref())
1929 }
1930
1931 /// Copies the contents of one file to another. This function will also
1932 /// copy the permission bits of the original file to the destination file.
1933 ///
1934 /// This function will **overwrite** the contents of `to`.
1935 ///
1936 /// Note that if `from` and `to` both point to the same file, then the file
1937 /// will likely get truncated by this operation.
1938 ///
1939 /// On success, the total number of bytes copied is returned and it is equal to
1940 /// the length of the `to` file as reported by `metadata`.
1941 ///
1942 /// If you want to copy the contents of one file to another and you’re
1943 /// working with [`File`]s, see the [`io::copy()`] function.
1944 ///
1945 /// # Platform-specific behavior
1946 ///
1947 /// This function currently corresponds to the `open` function in Unix
1948 /// with `O_RDONLY` for `from` and `O_WRONLY`, `O_CREAT`, and `O_TRUNC` for `to`.
1949 /// `O_CLOEXEC` is set for returned file descriptors.
1950 ///
1951 /// On Linux (including Android), this function attempts to use `copy_file_range(2)`,
1952 /// and falls back to reading and writing if that is not possible.
1953 ///
1954 /// On Windows, this function currently corresponds to `CopyFileEx`. Alternate
1955 /// NTFS streams are copied but only the size of the main stream is returned by
1956 /// this function.
1957 ///
1958 /// On MacOS, this function corresponds to `fclonefileat` and `fcopyfile`.
1959 ///
1960 /// Note that platform-specific behavior [may change in the future][changes].
1961 ///
1962 /// [changes]: io#platform-specific-behavior
1963 ///
1964 /// # Errors
1965 ///
1966 /// This function will return an error in the following situations, but is not
1967 /// limited to just these cases:
1968 ///
1969 /// * `from` is neither a regular file nor a symlink to a regular file.
1970 /// * `from` does not exist.
1971 /// * The current process does not have the permission rights to read
1972 /// `from` or write `to`.
1973 ///
1974 /// # Examples
1975 ///
1976 /// ```no_run
1977 /// use std::fs;
1978 ///
1979 /// fn main() -> std::io::Result<()> {
1980 /// fs::copy("foo.txt", "bar.txt")?; // Copy foo.txt to bar.txt
1981 /// Ok(())
1982 /// }
1983 /// ```
copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<u64>1984 pub fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<u64> {
1985 fs_imp::copy(from.as_ref(), to.as_ref())
1986 }
1987
1988 /// Creates a new hard link on the filesystem.
1989 ///
1990 /// The `link` path will be a link pointing to the `original` path. Note that
1991 /// systems often require these two paths to both be located on the same
1992 /// filesystem.
1993 ///
1994 /// If `original` names a symbolic link, it is platform-specific whether the
1995 /// symbolic link is followed. On platforms where it's possible to not follow
1996 /// it, it is not followed, and the created hard link points to the symbolic
1997 /// link itself.
1998 ///
1999 /// # Platform-specific behavior
2000 ///
2001 /// This function currently corresponds the `CreateHardLink` function on Windows.
2002 /// On most Unix systems, it corresponds to the `linkat` function with no flags.
2003 /// On Android, VxWorks, and Redox, it instead corresponds to the `link` function.
2004 /// On MacOS, it uses the `linkat` function if it is available, but on very old
2005 /// systems where `linkat` is not available, `link` is selected at runtime instead.
2006 /// Note that, this [may change in the future][changes].
2007 ///
2008 /// [changes]: io#platform-specific-behavior
2009 ///
2010 /// # Errors
2011 ///
2012 /// This function will return an error in the following situations, but is not
2013 /// limited to just these cases:
2014 ///
2015 /// * The `original` path is not a file or doesn't exist.
2016 ///
2017 /// # Examples
2018 ///
2019 /// ```no_run
2020 /// use std::fs;
2021 ///
2022 /// fn main() -> std::io::Result<()> {
2023 /// fs::hard_link("a.txt", "b.txt")?; // Hard link a.txt to b.txt
2024 /// Ok(())
2025 /// }
2026 /// ```
hard_link<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Result<()>2027 pub fn hard_link<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Result<()> {
2028 fs_imp::link(original.as_ref(), link.as_ref())
2029 }
2030
2031 /// Creates a new symbolic link on the filesystem.
2032 ///
2033 /// The `link` path will be a symbolic link pointing to the `original` path.
2034 /// On Windows, this will be a file symlink, not a directory symlink;
2035 /// for this reason, the platform-specific [`std::os::unix::fs::symlink`]
2036 /// and [`std::os::windows::fs::symlink_file`] or [`symlink_dir`] should be
2037 /// used instead to make the intent explicit.
2038 ///
2039 /// [`std::os::unix::fs::symlink`]: crate::std::os::unix::fs::symlink
2040 /// [`std::os::windows::fs::symlink_file`]: crate::std::os::windows::fs::symlink_file
2041 /// [`symlink_dir`]: crate::std::os::windows::fs::symlink_dir
2042 ///
2043 /// # Examples
2044 ///
2045 /// ```no_run
2046 /// use std::fs;
2047 ///
2048 /// fn main() -> std::io::Result<()> {
2049 /// fs::soft_link("a.txt", "b.txt")?;
2050 /// Ok(())
2051 /// }
2052 /// ```
2053 #[deprecated(
2054 since = "1.1.0",
2055 note = "replaced with std::os::unix::fs::symlink and \
2056 std::os::windows::fs::{symlink_file, symlink_dir}"
2057 )]
soft_link<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Result<()>2058 pub fn soft_link<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Result<()> {
2059 fs_imp::symlink(original.as_ref(), link.as_ref())
2060 }
2061
2062 /// Reads a symbolic link, returning the file that the link points to.
2063 ///
2064 /// # Platform-specific behavior
2065 ///
2066 /// This function currently corresponds to the `readlink` function on Unix
2067 /// and the `CreateFile` function with `FILE_FLAG_OPEN_REPARSE_POINT` and
2068 /// `FILE_FLAG_BACKUP_SEMANTICS` flags on Windows.
2069 /// Note that, this [may change in the future][changes].
2070 ///
2071 /// [changes]: io#platform-specific-behavior
2072 ///
2073 /// # Errors
2074 ///
2075 /// This function will return an error in the following situations, but is not
2076 /// limited to just these cases:
2077 ///
2078 /// * `path` is not a symbolic link.
2079 /// * `path` does not exist.
2080 ///
2081 /// # Examples
2082 ///
2083 /// ```no_run
2084 /// use std::fs;
2085 ///
2086 /// fn main() -> std::io::Result<()> {
2087 /// let path = fs::read_link("a.txt")?;
2088 /// Ok(())
2089 /// }
2090 /// ```
read_link<P: AsRef<Path>>(path: P) -> io::Result<PathBuf>2091 pub fn read_link<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
2092 fs_imp::readlink(path.as_ref())
2093 }
2094
2095 /// Returns the canonical, absolute form of a path with all intermediate
2096 /// components normalized and symbolic links resolved.
2097 ///
2098 /// # Platform-specific behavior
2099 ///
2100 /// This function currently corresponds to the `realpath` function on Unix
2101 /// and the `CreateFile` and `GetFinalPathNameByHandle` functions on Windows.
2102 /// Note that, this [may change in the future][changes].
2103 ///
2104 /// On Windows, this converts the path to use [extended length path][path]
2105 /// syntax, which allows your program to use longer path names, but means you
2106 /// can only join backslash-delimited paths to it, and it may be incompatible
2107 /// with other applications (if passed to the application on the command-line,
2108 /// or written to a file another application may read).
2109 ///
2110 /// [changes]: io#platform-specific-behavior
2111 /// [path]: https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file
2112 ///
2113 /// # Errors
2114 ///
2115 /// This function will return an error in the following situations, but is not
2116 /// limited to just these cases:
2117 ///
2118 /// * `path` does not exist.
2119 /// * A non-final component in path is not a directory.
2120 ///
2121 /// # Examples
2122 ///
2123 /// ```no_run
2124 /// use std::fs;
2125 ///
2126 /// fn main() -> std::io::Result<()> {
2127 /// let path = fs::canonicalize("../a/../foo.txt")?;
2128 /// Ok(())
2129 /// }
2130 /// ```
2131 #[doc(alias = "realpath")]
2132 #[doc(alias = "GetFinalPathNameByHandle")]
canonicalize<P: AsRef<Path>>(path: P) -> io::Result<PathBuf>2133 pub fn canonicalize<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
2134 fs_imp::canonicalize(path.as_ref())
2135 }
2136
2137 /// Creates a new, empty directory at the provided path
2138 ///
2139 /// # Platform-specific behavior
2140 ///
2141 /// This function currently corresponds to the `mkdir` function on Unix
2142 /// and the `CreateDirectory` function on Windows.
2143 /// Note that, this [may change in the future][changes].
2144 ///
2145 /// [changes]: io#platform-specific-behavior
2146 ///
2147 /// **NOTE**: If a parent of the given path doesn't exist, this function will
2148 /// return an error. To create a directory and all its missing parents at the
2149 /// same time, use the [`create_dir_all`] function.
2150 ///
2151 /// # Errors
2152 ///
2153 /// This function will return an error in the following situations, but is not
2154 /// limited to just these cases:
2155 ///
2156 /// * User lacks permissions to create directory at `path`.
2157 /// * A parent of the given path doesn't exist. (To create a directory and all
2158 /// its missing parents at the same time, use the [`create_dir_all`]
2159 /// function.)
2160 /// * `path` already exists.
2161 ///
2162 /// # Examples
2163 ///
2164 /// ```no_run
2165 /// use std::fs;
2166 ///
2167 /// fn main() -> std::io::Result<()> {
2168 /// fs::create_dir("/some/dir")?;
2169 /// Ok(())
2170 /// }
2171 /// ```
2172 #[doc(alias = "mkdir")]
create_dir<P: AsRef<Path>>(path: P) -> io::Result<()>2173 pub fn create_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
2174 DirBuilder::new().create(path.as_ref())
2175 }
2176
2177 /// Recursively create a directory and all of its parent components if they
2178 /// are missing.
2179 ///
2180 /// # Platform-specific behavior
2181 ///
2182 /// This function currently corresponds to the `mkdir` function on Unix
2183 /// and the `CreateDirectory` function on Windows.
2184 /// Note that, this [may change in the future][changes].
2185 ///
2186 /// [changes]: io#platform-specific-behavior
2187 ///
2188 /// # Errors
2189 ///
2190 /// This function will return an error in the following situations, but is not
2191 /// limited to just these cases:
2192 ///
2193 /// * If any directory in the path specified by `path`
2194 /// does not already exist and it could not be created otherwise. The specific
2195 /// error conditions for when a directory is being created (after it is
2196 /// determined to not exist) are outlined by [`fs::create_dir`].
2197 ///
2198 /// Notable exception is made for situations where any of the directories
2199 /// specified in the `path` could not be created as it was being created concurrently.
2200 /// Such cases are considered to be successful. That is, calling `create_dir_all`
2201 /// concurrently from multiple threads or processes is guaranteed not to fail
2202 /// due to a race condition with itself.
2203 ///
2204 /// [`fs::create_dir`]: create_dir
2205 ///
2206 /// # Examples
2207 ///
2208 /// ```no_run
2209 /// use std::fs;
2210 ///
2211 /// fn main() -> std::io::Result<()> {
2212 /// fs::create_dir_all("/some/dir")?;
2213 /// Ok(())
2214 /// }
2215 /// ```
create_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()>2216 pub fn create_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
2217 DirBuilder::new().recursive(true).create(path.as_ref())
2218 }
2219
2220 /// Removes an empty directory.
2221 ///
2222 /// # Platform-specific behavior
2223 ///
2224 /// This function currently corresponds to the `rmdir` function on Unix
2225 /// and the `RemoveDirectory` function on Windows.
2226 /// Note that, this [may change in the future][changes].
2227 ///
2228 /// [changes]: io#platform-specific-behavior
2229 ///
2230 /// # Errors
2231 ///
2232 /// This function will return an error in the following situations, but is not
2233 /// limited to just these cases:
2234 ///
2235 /// * `path` doesn't exist.
2236 /// * `path` isn't a directory.
2237 /// * The user lacks permissions to remove the directory at the provided `path`.
2238 /// * The directory isn't empty.
2239 ///
2240 /// # Examples
2241 ///
2242 /// ```no_run
2243 /// use std::fs;
2244 ///
2245 /// fn main() -> std::io::Result<()> {
2246 /// fs::remove_dir("/some/dir")?;
2247 /// Ok(())
2248 /// }
2249 /// ```
2250 #[doc(alias = "rmdir")]
remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()>2251 pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
2252 fs_imp::rmdir(path.as_ref())
2253 }
2254
2255 /// Removes a directory at this path, after removing all its contents. Use
2256 /// carefully!
2257 ///
2258 /// This function does **not** follow symbolic links and it will simply remove the
2259 /// symbolic link itself.
2260 ///
2261 /// # Platform-specific behavior
2262 ///
2263 /// This function currently corresponds to `openat`, `fdopendir`, `unlinkat` and `lstat` functions
2264 /// on Unix (except for macOS before version 10.10 and REDOX) and the `CreateFileW`,
2265 /// `GetFileInformationByHandleEx`, `SetFileInformationByHandle`, and `NtCreateFile` functions on
2266 /// Windows. Note that, this [may change in the future][changes].
2267 ///
2268 /// [changes]: io#platform-specific-behavior
2269 ///
2270 /// On macOS before version 10.10 and REDOX, as well as when running in Miri for any target, this
2271 /// function is not protected against time-of-check to time-of-use (TOCTOU) race conditions, and
2272 /// should not be used in security-sensitive code on those platforms. All other platforms are
2273 /// protected.
2274 ///
2275 /// # Errors
2276 ///
2277 /// See [`fs::remove_file`] and [`fs::remove_dir`].
2278 ///
2279 /// `remove_dir_all` will fail if `remove_dir` or `remove_file` fail on any constituent paths, including the root path.
2280 /// As a result, the directory you are deleting must exist, meaning that this function is not idempotent.
2281 ///
2282 /// Consider ignoring the error if validating the removal is not required for your use case.
2283 ///
2284 /// [`fs::remove_file`]: remove_file
2285 /// [`fs::remove_dir`]: remove_dir
2286 ///
2287 /// # Examples
2288 ///
2289 /// ```no_run
2290 /// use std::fs;
2291 ///
2292 /// fn main() -> std::io::Result<()> {
2293 /// fs::remove_dir_all("/some/dir")?;
2294 /// Ok(())
2295 /// }
2296 /// ```
remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()>2297 pub fn remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
2298 fs_imp::remove_dir_all(path.as_ref())
2299 }
2300
2301 /// Returns an iterator over the entries within a directory.
2302 ///
2303 /// The iterator will yield instances of <code>[io::Result]<[DirEntry]></code>.
2304 /// New errors may be encountered after an iterator is initially constructed.
2305 /// Entries for the current and parent directories (typically `.` and `..`) are
2306 /// skipped.
2307 ///
2308 /// # Platform-specific behavior
2309 ///
2310 /// This function currently corresponds to the `opendir` function on Unix
2311 /// and the `FindFirstFile` function on Windows. Advancing the iterator
2312 /// currently corresponds to `readdir` on Unix and `FindNextFile` on Windows.
2313 /// Note that, this [may change in the future][changes].
2314 ///
2315 /// [changes]: io#platform-specific-behavior
2316 ///
2317 /// The order in which this iterator returns entries is platform and filesystem
2318 /// dependent.
2319 ///
2320 /// # Errors
2321 ///
2322 /// This function will return an error in the following situations, but is not
2323 /// limited to just these cases:
2324 ///
2325 /// * The provided `path` doesn't exist.
2326 /// * The process lacks permissions to view the contents.
2327 /// * The `path` points at a non-directory file.
2328 ///
2329 /// # Examples
2330 ///
2331 /// ```
2332 /// use std::io;
2333 /// use std::fs::{self, DirEntry};
2334 /// use std::path::Path;
2335 ///
2336 /// // one possible implementation of walking a directory only visiting files
2337 /// fn visit_dirs(dir: &Path, cb: &dyn Fn(&DirEntry)) -> io::Result<()> {
2338 /// if dir.is_dir() {
2339 /// for entry in fs::read_dir(dir)? {
2340 /// let entry = entry?;
2341 /// let path = entry.path();
2342 /// if path.is_dir() {
2343 /// visit_dirs(&path, cb)?;
2344 /// } else {
2345 /// cb(&entry);
2346 /// }
2347 /// }
2348 /// }
2349 /// Ok(())
2350 /// }
2351 /// ```
2352 ///
2353 /// ```rust,no_run
2354 /// use std::{fs, io};
2355 ///
2356 /// fn main() -> io::Result<()> {
2357 /// let mut entries = fs::read_dir(".")?
2358 /// .map(|res| res.map(|e| e.path()))
2359 /// .collect::<Result<Vec<_>, io::Error>>()?;
2360 ///
2361 /// // The order in which `read_dir` returns entries is not guaranteed. If reproducible
2362 /// // ordering is required the entries should be explicitly sorted.
2363 ///
2364 /// entries.sort();
2365 ///
2366 /// // The entries have now been sorted by their path.
2367 ///
2368 /// Ok(())
2369 /// }
2370 /// ```
read_dir<P: AsRef<Path>>(path: P) -> io::Result<ReadDir>2371 pub fn read_dir<P: AsRef<Path>>(path: P) -> io::Result<ReadDir> {
2372 fs_imp::readdir(path.as_ref()).map(ReadDir)
2373 }
2374
2375 /// Changes the permissions found on a file or a directory.
2376 ///
2377 /// # Platform-specific behavior
2378 ///
2379 /// This function currently corresponds to the `chmod` function on Unix
2380 /// and the `SetFileAttributes` function on Windows.
2381 /// Note that, this [may change in the future][changes].
2382 ///
2383 /// [changes]: io#platform-specific-behavior
2384 ///
2385 /// # Errors
2386 ///
2387 /// This function will return an error in the following situations, but is not
2388 /// limited to just these cases:
2389 ///
2390 /// * `path` does not exist.
2391 /// * The user lacks the permission to change attributes of the file.
2392 ///
2393 /// # Examples
2394 ///
2395 /// ```no_run
2396 /// use std::fs;
2397 ///
2398 /// fn main() -> std::io::Result<()> {
2399 /// let mut perms = fs::metadata("foo.txt")?.permissions();
2400 /// perms.set_readonly(true);
2401 /// fs::set_permissions("foo.txt", perms)?;
2402 /// Ok(())
2403 /// }
2404 /// ```
set_permissions<P: AsRef<Path>>(path: P, perm: Permissions) -> io::Result<()>2405 pub fn set_permissions<P: AsRef<Path>>(path: P, perm: Permissions) -> io::Result<()> {
2406 fs_imp::set_perm(path.as_ref(), perm.0)
2407 }
2408
2409 impl DirBuilder {
2410 /// Creates a new set of options with default mode/security settings for all
2411 /// platforms and also non-recursive.
2412 ///
2413 /// # Examples
2414 ///
2415 /// ```
2416 /// use std::fs::DirBuilder;
2417 ///
2418 /// let builder = DirBuilder::new();
2419 /// ```
2420 #[must_use]
new() -> DirBuilder2421 pub fn new() -> DirBuilder {
2422 DirBuilder {
2423 inner: fs_imp::DirBuilder::new(),
2424 recursive: false,
2425 }
2426 }
2427
2428 /// Indicates that directories should be created recursively, creating all
2429 /// parent directories. Parents that do not exist are created with the same
2430 /// security and permissions settings.
2431 ///
2432 /// This option defaults to `false`.
2433 ///
2434 /// # Examples
2435 ///
2436 /// ```
2437 /// use std::fs::DirBuilder;
2438 ///
2439 /// let mut builder = DirBuilder::new();
2440 /// builder.recursive(true);
2441 /// ```
recursive(&mut self, recursive: bool) -> &mut Self2442 pub fn recursive(&mut self, recursive: bool) -> &mut Self {
2443 self.recursive = recursive;
2444 self
2445 }
2446
2447 /// Creates the specified directory with the options configured in this
2448 /// builder.
2449 ///
2450 /// It is considered an error if the directory already exists unless
2451 /// recursive mode is enabled.
2452 ///
2453 /// # Examples
2454 ///
2455 /// ```no_run
2456 /// use std::fs::{self, DirBuilder};
2457 ///
2458 /// let path = "/tmp/foo/bar/baz";
2459 /// DirBuilder::new()
2460 /// .recursive(true)
2461 /// .create(path).unwrap();
2462 ///
2463 /// assert!(fs::metadata(path).unwrap().is_dir());
2464 /// ```
create<P: AsRef<Path>>(&self, path: P) -> io::Result<()>2465 pub fn create<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
2466 self._create(path.as_ref())
2467 }
2468
_create(&self, path: &Path) -> io::Result<()>2469 fn _create(&self, path: &Path) -> io::Result<()> {
2470 if self.recursive {
2471 self.create_dir_all(path)
2472 } else {
2473 self.inner.mkdir(path)
2474 }
2475 }
2476
create_dir_all(&self, path: &Path) -> io::Result<()>2477 fn create_dir_all(&self, path: &Path) -> io::Result<()> {
2478 if path == Path::new("") {
2479 return Ok(());
2480 }
2481
2482 match self.inner.mkdir(path) {
2483 Ok(()) => return Ok(()),
2484 Err(ref e) if e.kind() == io::ErrorKind::NotFound => {}
2485 Err(_) if path.is_dir() => return Ok(()),
2486 Err(e) => return Err(e),
2487 }
2488 match path.parent() {
2489 Some(p) => self.create_dir_all(p)?,
2490 None => {
2491 return Err(io::const_io_error!(
2492 io::ErrorKind::Uncategorized,
2493 "failed to create whole tree",
2494 ));
2495 }
2496 }
2497 match self.inner.mkdir(path) {
2498 Ok(()) => Ok(()),
2499 Err(_) if path.is_dir() => Ok(()),
2500 Err(e) => Err(e),
2501 }
2502 }
2503 }
2504
2505 impl AsInnerMut<fs_imp::DirBuilder> for DirBuilder {
2506 #[inline]
as_inner_mut(&mut self) -> &mut fs_imp::DirBuilder2507 fn as_inner_mut(&mut self) -> &mut fs_imp::DirBuilder {
2508 &mut self.inner
2509 }
2510 }
2511
2512 /// Returns `Ok(true)` if the path points at an existing entity.
2513 ///
2514 /// This function will traverse symbolic links to query information about the
2515 /// destination file. In case of broken symbolic links this will return `Ok(false)`.
2516 ///
2517 /// As opposed to the [`Path::exists`] method, this will only return `Ok(true)` or `Ok(false)`
2518 /// if the path was _verified_ to exist or not exist. If its existence can neither be confirmed
2519 /// nor denied, an `Err(_)` will be propagated instead. This can be the case if e.g. listing
2520 /// permission is denied on one of the parent directories.
2521 ///
2522 /// Note that while this avoids some pitfalls of the `exists()` method, it still can not
2523 /// prevent time-of-check to time-of-use (TOCTOU) bugs. You should only use it in scenarios
2524 /// where those bugs are not an issue.
2525 ///
2526 /// # Examples
2527 ///
2528 /// ```no_run
2529 /// #![feature(fs_try_exists)]
2530 /// use std::fs;
2531 ///
2532 /// assert!(!fs::try_exists("does_not_exist.txt").expect("Can't check existence of file does_not_exist.txt"));
2533 /// assert!(fs::try_exists("/root/secret_file.txt").is_err());
2534 /// ```
2535 ///
2536 /// [`Path::exists`]: crate::std::path::Path::exists
2537 // FIXME: stabilization should modify documentation of `exists()` to recommend this method
2538 // instead.
2539 #[inline]
try_exists<P: AsRef<Path>>(path: P) -> io::Result<bool>2540 pub fn try_exists<P: AsRef<Path>>(path: P) -> io::Result<bool> {
2541 fs_imp::try_exists(path.as_ref())
2542 }
2543