1//! Types for working with [`File`].
2//!
3//! [`File`]: File
4
5use crate::fs::{asyncify, OpenOptions};
6use crate::io::blocking::Buf;
7use crate::io::{AsyncRead, AsyncSeek, AsyncWrite, ReadBuf};
8use crate::sync::Mutex;
9
10use std::fmt;
11use std::fs::{Metadata, Permissions};
12use std::future::Future;
13use std::io::{self, Seek, SeekFrom};
14use std::path::Path;
15use std::pin::Pin;
16use std::sync::Arc;
17use std::task::Context;
18use std::task::Poll;
19
20#[cfg(test)]
21use super::mocks::JoinHandle;
22#[cfg(test)]
23use super::mocks::MockFile as StdFile;
24#[cfg(test)]
25use super::mocks::{spawn_blocking, spawn_mandatory_blocking};
26#[cfg(not(test))]
27use crate::blocking::JoinHandle;
28#[cfg(not(test))]
29use crate::blocking::{spawn_blocking, spawn_mandatory_blocking};
30#[cfg(not(test))]
31use std::fs::File as StdFile;
32
33/// A reference to an open file on the filesystem.
34///
35/// This is a specialized version of [`std::fs::File`] for usage from the
36/// Tokio runtime.
37///
38/// An instance of a `File` can be read and/or written depending on what options
39/// it was opened with. Files also implement [`AsyncSeek`] to alter the logical
40/// cursor that the file contains internally.
41///
42/// A file will not be closed immediately when it goes out of scope if there
43/// are any IO operations that have not yet completed. To ensure that a file is
44/// closed immediately when it is dropped, you should call [`flush`] before
45/// dropping it. Note that this does not ensure that the file has been fully
46/// written to disk; the operating system might keep the changes around in an
47/// in-memory buffer. See the [`sync_all`] method for telling the OS to write
48/// the data to disk.
49///
50/// Reading and writing to a `File` is usually done using the convenience
51/// methods found on the [`AsyncReadExt`] and [`AsyncWriteExt`] traits.
52///
53/// [`AsyncSeek`]: trait@crate::io::AsyncSeek
54/// [`flush`]: fn@crate::io::AsyncWriteExt::flush
55/// [`sync_all`]: fn@crate::fs::File::sync_all
56/// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
57/// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
58///
59/// # Examples
60///
61/// Create a new file and asynchronously write bytes to it:
62///
63/// ```no_run
64/// use tokio::fs::File;
65/// use tokio::io::AsyncWriteExt; // for write_all()
66///
67/// # async fn dox() -> std::io::Result<()> {
68/// let mut file = File::create("foo.txt").await?;
69/// file.write_all(b"hello, world!").await?;
70/// # Ok(())
71/// # }
72/// ```
73///
74/// Read the contents of a file into a buffer:
75///
76/// ```no_run
77/// use tokio::fs::File;
78/// use tokio::io::AsyncReadExt; // for read_to_end()
79///
80/// # async fn dox() -> std::io::Result<()> {
81/// let mut file = File::open("foo.txt").await?;
82///
83/// let mut contents = vec![];
84/// file.read_to_end(&mut contents).await?;
85///
86/// println!("len = {}", contents.len());
87/// # Ok(())
88/// # }
89/// ```
90pub struct File {
91 std: Arc<StdFile>,
92 inner: Mutex<Inner>,
93}
94
95struct Inner {
96 state: State,
97
98 /// Errors from writes/flushes are returned in write/flush calls. If a write
99 /// error is observed while performing a read, it is saved until the next
100 /// write / flush call.
101 last_write_err: Option<io::ErrorKind>,
102
103 pos: u64,
104}
105
106#[derive(Debug)]
107enum State {
108 Idle(Option<Buf>),
109 Busy(JoinHandle<(Operation, Buf)>),
110}
111
112#[derive(Debug)]
113enum Operation {
114 Read(io::Result<usize>),
115 Write(io::Result<()>),
116 Seek(io::Result<u64>),
117}
118
119impl File {
120 /// Attempts to open a file in read-only mode.
121 ///
122 /// See [`OpenOptions`] for more details.
123 ///
124 /// # Errors
125 ///
126 /// This function will return an error if called from outside of the Tokio
127 /// runtime or if path does not already exist. Other errors may also be
128 /// returned according to `OpenOptions::open`.
129 ///
130 /// # Examples
131 ///
132 /// ```no_run
133 /// use tokio::fs::File;
134 /// use tokio::io::AsyncReadExt;
135 ///
136 /// # async fn dox() -> std::io::Result<()> {
137 /// let mut file = File::open("foo.txt").await?;
138 ///
139 /// let mut contents = vec![];
140 /// file.read_to_end(&mut contents).await?;
141 ///
142 /// println!("len = {}", contents.len());
143 /// # Ok(())
144 /// # }
145 /// ```
146 ///
147 /// The [`read_to_end`] method is defined on the [`AsyncReadExt`] trait.
148 ///
149 /// [`read_to_end`]: fn@crate::io::AsyncReadExt::read_to_end
150 /// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt
151 pub async fn open(path: impl AsRef<Path>) -> io::Result<File> {
152 let path = path.as_ref().to_owned();
153 let std = asyncify(|| StdFile::open(path)).await?;
154
155 Ok(File::from_std(std))
156 }
157
158 /// Opens a file in write-only mode.
159 ///
160 /// This function will create a file if it does not exist, and will truncate
161 /// it if it does.
162 ///
163 /// See [`OpenOptions`] for more details.
164 ///
165 /// # Errors
166 ///
167 /// Results in an error if called from outside of the Tokio runtime or if
168 /// the underlying [`create`] call results in an error.
169 ///
170 /// [`create`]: std::fs::File::create
171 ///
172 /// # Examples
173 ///
174 /// ```no_run
175 /// use tokio::fs::File;
176 /// use tokio::io::AsyncWriteExt;
177 ///
178 /// # async fn dox() -> std::io::Result<()> {
179 /// let mut file = File::create("foo.txt").await?;
180 /// file.write_all(b"hello, world!").await?;
181 /// # Ok(())
182 /// # }
183 /// ```
184 ///
185 /// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait.
186 ///
187 /// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all
188 /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
189 pub async fn create(path: impl AsRef<Path>) -> io::Result<File> {
190 let path = path.as_ref().to_owned();
191 let std_file = asyncify(move || StdFile::create(path)).await?;
192 Ok(File::from_std(std_file))
193 }
194
195 /// Returns a new [`OpenOptions`] object.
196 ///
197 /// This function returns a new `OpenOptions` object that you can use to
198 /// open or create a file with specific options if `open()` or `create()`
199 /// are not appropriate.
200 ///
201 /// It is equivalent to `OpenOptions::new()`, but allows you to write more
202 /// readable code. Instead of
203 /// `OpenOptions::new().append(true).open("example.log")`,
204 /// you can write `File::options().append(true).open("example.log")`. This
205 /// also avoids the need to import `OpenOptions`.
206 ///
207 /// See the [`OpenOptions::new`] function for more details.
208 ///
209 /// # Examples
210 ///
211 /// ```no_run
212 /// use tokio::fs::File;
213 /// use tokio::io::AsyncWriteExt;
214 ///
215 /// # async fn dox() -> std::io::Result<()> {
216 /// let mut f = File::options().append(true).open("example.log").await?;
217 /// f.write_all(b"new line\n").await?;
218 /// # Ok(())
219 /// # }
220 /// ```
221 #[must_use]
222 pub fn options() -> OpenOptions {
223 OpenOptions::new()
224 }
225
226 /// Converts a [`std::fs::File`] to a [`tokio::fs::File`](File).
227 ///
228 /// # Examples
229 ///
230 /// ```no_run
231 /// // This line could block. It is not recommended to do this on the Tokio
232 /// // runtime.
233 /// let std_file = std::fs::File::open("foo.txt").unwrap();
234 /// let file = tokio::fs::File::from_std(std_file);
235 /// ```
236 pub fn from_std(std: StdFile) -> File {
237 File {
238 std: Arc::new(std),
239 inner: Mutex::new(Inner {
240 state: State::Idle(Some(Buf::with_capacity(0))),
241 last_write_err: None,
242 pos: 0,
243 }),
244 }
245 }
246
247 /// Attempts to sync all OS-internal metadata to disk.
248 ///
249 /// This function will attempt to ensure that all in-core data reaches the
250 /// filesystem before returning.
251 ///
252 /// # Examples
253 ///
254 /// ```no_run
255 /// use tokio::fs::File;
256 /// use tokio::io::AsyncWriteExt;
257 ///
258 /// # async fn dox() -> std::io::Result<()> {
259 /// let mut file = File::create("foo.txt").await?;
260 /// file.write_all(b"hello, world!").await?;
261 /// file.sync_all().await?;
262 /// # Ok(())
263 /// # }
264 /// ```
265 ///
266 /// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait.
267 ///
268 /// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all
269 /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
270 pub async fn sync_all(&self) -> io::Result<()> {
271 let mut inner = self.inner.lock().await;
272 inner.complete_inflight().await;
273
274 let std = self.std.clone();
275 asyncify(move || std.sync_all()).await
276 }
277
278 /// This function is similar to `sync_all`, except that it may not
279 /// synchronize file metadata to the filesystem.
280 ///
281 /// This is intended for use cases that must synchronize content, but don't
282 /// need the metadata on disk. The goal of this method is to reduce disk
283 /// operations.
284 ///
285 /// Note that some platforms may simply implement this in terms of `sync_all`.
286 ///
287 /// # Examples
288 ///
289 /// ```no_run
290 /// use tokio::fs::File;
291 /// use tokio::io::AsyncWriteExt;
292 ///
293 /// # async fn dox() -> std::io::Result<()> {
294 /// let mut file = File::create("foo.txt").await?;
295 /// file.write_all(b"hello, world!").await?;
296 /// file.sync_data().await?;
297 /// # Ok(())
298 /// # }
299 /// ```
300 ///
301 /// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait.
302 ///
303 /// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all
304 /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
305 pub async fn sync_data(&self) -> io::Result<()> {
306 let mut inner = self.inner.lock().await;
307 inner.complete_inflight().await;
308
309 let std = self.std.clone();
310 asyncify(move || std.sync_data()).await
311 }
312
313 /// Truncates or extends the underlying file, updating the size of this file to become size.
314 ///
315 /// If the size is less than the current file's size, then the file will be
316 /// shrunk. If it is greater than the current file's size, then the file
317 /// will be extended to size and have all of the intermediate data filled in
318 /// with 0s.
319 ///
320 /// # Errors
321 ///
322 /// This function will return an error if the file is not opened for
323 /// writing.
324 ///
325 /// # Examples
326 ///
327 /// ```no_run
328 /// use tokio::fs::File;
329 /// use tokio::io::AsyncWriteExt;
330 ///
331 /// # async fn dox() -> std::io::Result<()> {
332 /// let mut file = File::create("foo.txt").await?;
333 /// file.write_all(b"hello, world!").await?;
334 /// file.set_len(10).await?;
335 /// # Ok(())
336 /// # }
337 /// ```
338 ///
339 /// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait.
340 ///
341 /// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all
342 /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
343 pub async fn set_len(&self, size: u64) -> io::Result<()> {
344 let mut inner = self.inner.lock().await;
345 inner.complete_inflight().await;
346
347 let mut buf = match inner.state {
348 State::Idle(ref mut buf_cell) => buf_cell.take().unwrap(),
349 _ => unreachable!(),
350 };
351
352 let seek = if !buf.is_empty() {
353 Some(SeekFrom::Current(buf.discard_read()))
354 } else {
355 None
356 };
357
358 let std = self.std.clone();
359
360 inner.state = State::Busy(spawn_blocking(move || {
361 let res = if let Some(seek) = seek {
362 (&*std).seek(seek).and_then(|_| std.set_len(size))
363 } else {
364 std.set_len(size)
365 }
366 .map(|()| 0); // the value is discarded later
367
368 // Return the result as a seek
369 (Operation::Seek(res), buf)
370 }));
371
372 let (op, buf) = match inner.state {
373 State::Idle(_) => unreachable!(),
374 State::Busy(ref mut rx) => rx.await?,
375 };
376
377 inner.state = State::Idle(Some(buf));
378
379 match op {
380 Operation::Seek(res) => res.map(|pos| {
381 inner.pos = pos;
382 }),
383 _ => unreachable!(),
384 }
385 }
386
387 /// Queries metadata about the underlying file.
388 ///
389 /// # Examples
390 ///
391 /// ```no_run
392 /// use tokio::fs::File;
393 ///
394 /// # async fn dox() -> std::io::Result<()> {
395 /// let file = File::open("foo.txt").await?;
396 /// let metadata = file.metadata().await?;
397 ///
398 /// println!("{:?}", metadata);
399 /// # Ok(())
400 /// # }
401 /// ```
402 pub async fn metadata(&self) -> io::Result<Metadata> {
403 let std = self.std.clone();
404 asyncify(move || std.metadata()).await
405 }
406
407 /// Creates a new `File` instance that shares the same underlying file handle
408 /// as the existing `File` instance. Reads, writes, and seeks will affect both
409 /// File instances simultaneously.
410 ///
411 /// # Examples
412 ///
413 /// ```no_run
414 /// use tokio::fs::File;
415 ///
416 /// # async fn dox() -> std::io::Result<()> {
417 /// let file = File::open("foo.txt").await?;
418 /// let file_clone = file.try_clone().await?;
419 /// # Ok(())
420 /// # }
421 /// ```
422 pub async fn try_clone(&self) -> io::Result<File> {
423 self.inner.lock().await.complete_inflight().await;
424 let std = self.std.clone();
425 let std_file = asyncify(move || std.try_clone()).await?;
426 Ok(File::from_std(std_file))
427 }
428
429 /// Destructures `File` into a [`std::fs::File`]. This function is
430 /// async to allow any in-flight operations to complete.
431 ///
432 /// Use `File::try_into_std` to attempt conversion immediately.
433 ///
434 /// # Examples
435 ///
436 /// ```no_run
437 /// use tokio::fs::File;
438 ///
439 /// # async fn dox() -> std::io::Result<()> {
440 /// let tokio_file = File::open("foo.txt").await?;
441 /// let std_file = tokio_file.into_std().await;
442 /// # Ok(())
443 /// # }
444 /// ```
445 pub async fn into_std(mut self) -> StdFile {
446 self.inner.get_mut().complete_inflight().await;
447 Arc::try_unwrap(self.std).expect("Arc::try_unwrap failed")
448 }
449
450 /// Tries to immediately destructure `File` into a [`std::fs::File`].
451 ///
452 /// # Errors
453 ///
454 /// This function will return an error containing the file if some
455 /// operation is in-flight.
456 ///
457 /// # Examples
458 ///
459 /// ```no_run
460 /// use tokio::fs::File;
461 ///
462 /// # async fn dox() -> std::io::Result<()> {
463 /// let tokio_file = File::open("foo.txt").await?;
464 /// let std_file = tokio_file.try_into_std().unwrap();
465 /// # Ok(())
466 /// # }
467 /// ```
468 pub fn try_into_std(mut self) -> Result<StdFile, Self> {
469 match Arc::try_unwrap(self.std) {
470 Ok(file) => Ok(file),
471 Err(std_file_arc) => {
472 self.std = std_file_arc;
473 Err(self)
474 }
475 }
476 }
477
478 /// Changes the permissions on the underlying file.
479 ///
480 /// # Platform-specific behavior
481 ///
482 /// This function currently corresponds to the `fchmod` function on Unix and
483 /// the `SetFileInformationByHandle` function on Windows. Note that, this
484 /// [may change in the future][changes].
485 ///
486 /// [changes]: https://doc.rust-lang.org/std/io/index.html#platform-specific-behavior
487 ///
488 /// # Errors
489 ///
490 /// This function will return an error if the user lacks permission change
491 /// attributes on the underlying file. It may also return an error in other
492 /// os-specific unspecified cases.
493 ///
494 /// # Examples
495 ///
496 /// ```no_run
497 /// use tokio::fs::File;
498 ///
499 /// # async fn dox() -> std::io::Result<()> {
500 /// let file = File::open("foo.txt").await?;
501 /// let mut perms = file.metadata().await?.permissions();
502 /// perms.set_readonly(true);
503 /// file.set_permissions(perms).await?;
504 /// # Ok(())
505 /// # }
506 /// ```
507 pub async fn set_permissions(&self, perm: Permissions) -> io::Result<()> {
508 let std = self.std.clone();
509 asyncify(move || std.set_permissions(perm)).await
510 }
511}
512
513impl AsyncRead for File {
514 fn poll_read(
515 self: Pin<&mut Self>,
516 cx: &mut Context<'_>,
517 dst: &mut ReadBuf<'_>,
518 ) -> Poll<io::Result<()>> {
519 ready!(crate::trace::trace_leaf(cx));
520 let me = self.get_mut();
521 let inner = me.inner.get_mut();
522
523 loop {
524 match inner.state {
525 State::Idle(ref mut buf_cell) => {
526 let mut buf = buf_cell.take().unwrap();
527
528 if !buf.is_empty() {
529 buf.copy_to(dst);
530 *buf_cell = Some(buf);
531 return Poll::Ready(Ok(()));
532 }
533
534 buf.ensure_capacity_for(dst);
535 let std = me.std.clone();
536
537 inner.state = State::Busy(spawn_blocking(move || {
538 let res = buf.read_from(&mut &*std);
539 (Operation::Read(res), buf)
540 }));
541 }
542 State::Busy(ref mut rx) => {
543 let (op, mut buf) = ready!(Pin::new(rx).poll(cx))?;
544
545 match op {
546 Operation::Read(Ok(_)) => {
547 buf.copy_to(dst);
548 inner.state = State::Idle(Some(buf));
549 return Poll::Ready(Ok(()));
550 }
551 Operation::Read(Err(e)) => {
552 assert!(buf.is_empty());
553
554 inner.state = State::Idle(Some(buf));
555 return Poll::Ready(Err(e));
556 }
557 Operation::Write(Ok(())) => {
558 assert!(buf.is_empty());
559 inner.state = State::Idle(Some(buf));
560 continue;
561 }
562 Operation::Write(Err(e)) => {
563 assert!(inner.last_write_err.is_none());
564 inner.last_write_err = Some(e.kind());
565 inner.state = State::Idle(Some(buf));
566 }
567 Operation::Seek(result) => {
568 assert!(buf.is_empty());
569 inner.state = State::Idle(Some(buf));
570 if let Ok(pos) = result {
571 inner.pos = pos;
572 }
573 continue;
574 }
575 }
576 }
577 }
578 }
579 }
580}
581
582impl AsyncSeek for File {
583 fn start_seek(self: Pin<&mut Self>, mut pos: SeekFrom) -> io::Result<()> {
584 let me = self.get_mut();
585 let inner = me.inner.get_mut();
586
587 match inner.state {
588 State::Busy(_) => Err(io::Error::new(
589 io::ErrorKind::Other,
590 "other file operation is pending, call poll_complete before start_seek",
591 )),
592 State::Idle(ref mut buf_cell) => {
593 let mut buf = buf_cell.take().unwrap();
594
595 // Factor in any unread data from the buf
596 if !buf.is_empty() {
597 let n = buf.discard_read();
598
599 if let SeekFrom::Current(ref mut offset) = pos {
600 *offset += n;
601 }
602 }
603
604 let std = me.std.clone();
605
606 inner.state = State::Busy(spawn_blocking(move || {
607 let res = (&*std).seek(pos);
608 (Operation::Seek(res), buf)
609 }));
610 Ok(())
611 }
612 }
613 }
614
615 fn poll_complete(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<u64>> {
616 ready!(crate::trace::trace_leaf(cx));
617 let inner = self.inner.get_mut();
618
619 loop {
620 match inner.state {
621 State::Idle(_) => return Poll::Ready(Ok(inner.pos)),
622 State::Busy(ref mut rx) => {
623 let (op, buf) = ready!(Pin::new(rx).poll(cx))?;
624 inner.state = State::Idle(Some(buf));
625
626 match op {
627 Operation::Read(_) => {}
628 Operation::Write(Err(e)) => {
629 assert!(inner.last_write_err.is_none());
630 inner.last_write_err = Some(e.kind());
631 }
632 Operation::Write(_) => {}
633 Operation::Seek(res) => {
634 if let Ok(pos) = res {
635 inner.pos = pos;
636 }
637 return Poll::Ready(res);
638 }
639 }
640 }
641 }
642 }
643 }
644}
645
646impl AsyncWrite for File {
647 fn poll_write(
648 self: Pin<&mut Self>,
649 cx: &mut Context<'_>,
650 src: &[u8],
651 ) -> Poll<io::Result<usize>> {
652 ready!(crate::trace::trace_leaf(cx));
653 let me = self.get_mut();
654 let inner = me.inner.get_mut();
655
656 if let Some(e) = inner.last_write_err.take() {
657 return Poll::Ready(Err(e.into()));
658 }
659
660 loop {
661 match inner.state {
662 State::Idle(ref mut buf_cell) => {
663 let mut buf = buf_cell.take().unwrap();
664
665 let seek = if !buf.is_empty() {
666 Some(SeekFrom::Current(buf.discard_read()))
667 } else {
668 None
669 };
670
671 let n = buf.copy_from(src);
672 let std = me.std.clone();
673
674 let blocking_task_join_handle = spawn_mandatory_blocking(move || {
675 let res = if let Some(seek) = seek {
676 (&*std).seek(seek).and_then(|_| buf.write_to(&mut &*std))
677 } else {
678 buf.write_to(&mut &*std)
679 };
680
681 (Operation::Write(res), buf)
682 })
683 .ok_or_else(|| {
684 io::Error::new(io::ErrorKind::Other, "background task failed")
685 })?;
686
687 inner.state = State::Busy(blocking_task_join_handle);
688
689 return Poll::Ready(Ok(n));
690 }
691 State::Busy(ref mut rx) => {
692 let (op, buf) = ready!(Pin::new(rx).poll(cx))?;
693 inner.state = State::Idle(Some(buf));
694
695 match op {
696 Operation::Read(_) => {
697 // We don't care about the result here. The fact
698 // that the cursor has advanced will be reflected in
699 // the next iteration of the loop
700 continue;
701 }
702 Operation::Write(res) => {
703 // If the previous write was successful, continue.
704 // Otherwise, error.
705 res?;
706 continue;
707 }
708 Operation::Seek(_) => {
709 // Ignore the seek
710 continue;
711 }
712 }
713 }
714 }
715 }
716 }
717
718 fn poll_write_vectored(
719 self: Pin<&mut Self>,
720 cx: &mut Context<'_>,
721 bufs: &[io::IoSlice<'_>],
722 ) -> Poll<Result<usize, io::Error>> {
723 ready!(crate::trace::trace_leaf(cx));
724 let me = self.get_mut();
725 let inner = me.inner.get_mut();
726
727 if let Some(e) = inner.last_write_err.take() {
728 return Poll::Ready(Err(e.into()));
729 }
730
731 loop {
732 match inner.state {
733 State::Idle(ref mut buf_cell) => {
734 let mut buf = buf_cell.take().unwrap();
735
736 let seek = if !buf.is_empty() {
737 Some(SeekFrom::Current(buf.discard_read()))
738 } else {
739 None
740 };
741
742 let n = buf.copy_from_bufs(bufs);
743 let std = me.std.clone();
744
745 let blocking_task_join_handle = spawn_mandatory_blocking(move || {
746 let res = if let Some(seek) = seek {
747 (&*std).seek(seek).and_then(|_| buf.write_to(&mut &*std))
748 } else {
749 buf.write_to(&mut &*std)
750 };
751
752 (Operation::Write(res), buf)
753 })
754 .ok_or_else(|| {
755 io::Error::new(io::ErrorKind::Other, "background task failed")
756 })?;
757
758 inner.state = State::Busy(blocking_task_join_handle);
759
760 return Poll::Ready(Ok(n));
761 }
762 State::Busy(ref mut rx) => {
763 let (op, buf) = ready!(Pin::new(rx).poll(cx))?;
764 inner.state = State::Idle(Some(buf));
765
766 match op {
767 Operation::Read(_) => {
768 // We don't care about the result here. The fact
769 // that the cursor has advanced will be reflected in
770 // the next iteration of the loop
771 continue;
772 }
773 Operation::Write(res) => {
774 // If the previous write was successful, continue.
775 // Otherwise, error.
776 res?;
777 continue;
778 }
779 Operation::Seek(_) => {
780 // Ignore the seek
781 continue;
782 }
783 }
784 }
785 }
786 }
787 }
788
789 fn is_write_vectored(&self) -> bool {
790 true
791 }
792
793 fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
794 ready!(crate::trace::trace_leaf(cx));
795 let inner = self.inner.get_mut();
796 inner.poll_flush(cx)
797 }
798
799 fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
800 ready!(crate::trace::trace_leaf(cx));
801 self.poll_flush(cx)
802 }
803}
804
805impl From<StdFile> for File {
806 fn from(std: StdFile) -> Self {
807 Self::from_std(std)
808 }
809}
810
811impl fmt::Debug for File {
812 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
813 fmt.debug_struct("tokio::fs::File")
814 .field("std", &self.std)
815 .finish()
816 }
817}
818
819#[cfg(unix)]
820impl std::os::unix::io::AsRawFd for File {
821 fn as_raw_fd(&self) -> std::os::unix::io::RawFd {
822 self.std.as_raw_fd()
823 }
824}
825
826#[cfg(unix)]
827impl std::os::unix::io::AsFd for File {
828 fn as_fd(&self) -> std::os::unix::io::BorrowedFd<'_> {
829 unsafe {
830 std::os::unix::io::BorrowedFd::borrow_raw(std::os::unix::io::AsRawFd::as_raw_fd(self))
831 }
832 }
833}
834
835#[cfg(unix)]
836impl std::os::unix::io::FromRawFd for File {
837 unsafe fn from_raw_fd(fd: std::os::unix::io::RawFd) -> Self {
838 StdFile::from_raw_fd(fd).into()
839 }
840}
841
842cfg_windows! {
843 use crate::os::windows::io::{AsRawHandle, FromRawHandle, RawHandle, AsHandle, BorrowedHandle};
844
845 impl AsRawHandle for File {
846 fn as_raw_handle(&self) -> RawHandle {
847 self.std.as_raw_handle()
848 }
849 }
850
851 impl AsHandle for File {
852 fn as_handle(&self) -> BorrowedHandle<'_> {
853 unsafe {
854 BorrowedHandle::borrow_raw(
855 AsRawHandle::as_raw_handle(self),
856 )
857 }
858 }
859 }
860
861 impl FromRawHandle for File {
862 unsafe fn from_raw_handle(handle: RawHandle) -> Self {
863 StdFile::from_raw_handle(handle).into()
864 }
865 }
866}
867
868impl Inner {
869 async fn complete_inflight(&mut self) {
870 use crate::future::poll_fn;
871
872 poll_fn(|cx| self.poll_complete_inflight(cx)).await;
873 }
874
875 fn poll_complete_inflight(&mut self, cx: &mut Context<'_>) -> Poll<()> {
876 ready!(crate::trace::trace_leaf(cx));
877 match self.poll_flush(cx) {
878 Poll::Ready(Err(e)) => {
879 self.last_write_err = Some(e.kind());
880 Poll::Ready(())
881 }
882 Poll::Ready(Ok(())) => Poll::Ready(()),
883 Poll::Pending => Poll::Pending,
884 }
885 }
886
887 fn poll_flush(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
888 if let Some(e) = self.last_write_err.take() {
889 return Poll::Ready(Err(e.into()));
890 }
891
892 let (op, buf) = match self.state {
893 State::Idle(_) => return Poll::Ready(Ok(())),
894 State::Busy(ref mut rx) => ready!(Pin::new(rx).poll(cx))?,
895 };
896
897 // The buffer is not used here
898 self.state = State::Idle(Some(buf));
899
900 match op {
901 Operation::Read(_) => Poll::Ready(Ok(())),
902 Operation::Write(res) => Poll::Ready(res),
903 Operation::Seek(_) => Poll::Ready(Ok(())),
904 }
905 }
906}
907
908#[cfg(test)]
909mod tests;
910