1#![cfg_attr(test, allow(unused))]
2
3#[cfg(test)]
4mod tests;
5
6use crate::cell::{Cell, RefCell};
7use crate::fmt;
8use crate::fs::File;
9use crate::io::prelude::*;
10use crate::io::{
11 self, BorrowedCursor, BufReader, IoSlice, IoSliceMut, LineWriter, Lines, SpecReadByte,
12};
13use crate::panic::{RefUnwindSafe, UnwindSafe};
14use crate::sync::atomic::{Atomic, AtomicBool, Ordering};
15use crate::sync::{Arc, Mutex, MutexGuard, OnceLock, ReentrantLock, ReentrantLockGuard};
16use crate::sys::stdio;
17use crate::thread::AccessError;
18
19type LocalStream = Arc<Mutex<Vec<u8>>>;
20
21thread_local! {
22 /// Used by the test crate to capture the output of the print macros and panics.
23 static OUTPUT_CAPTURE: Cell<Option<LocalStream>> = const {
24 Cell::new(None)
25 }
26}
27
28/// Flag to indicate OUTPUT_CAPTURE is used.
29///
30/// If it is None and was never set on any thread, this flag is set to false,
31/// and OUTPUT_CAPTURE can be safely ignored on all threads, saving some time
32/// and memory registering an unused thread local.
33///
34/// Note about memory ordering: This contains information about whether a
35/// thread local variable might be in use. Although this is a global flag, the
36/// memory ordering between threads does not matter: we only want this flag to
37/// have a consistent order between set_output_capture and print_to *within
38/// the same thread*. Within the same thread, things always have a perfectly
39/// consistent order. So Ordering::Relaxed is fine.
40static OUTPUT_CAPTURE_USED: Atomic<bool> = AtomicBool::new(false);
41
42/// A handle to a raw instance of the standard input stream of this process.
43///
44/// This handle is not synchronized or buffered in any fashion. Constructed via
45/// the `std::io::stdio::stdin_raw` function.
46struct StdinRaw(stdio::Stdin);
47
48/// A handle to a raw instance of the standard output stream of this process.
49///
50/// This handle is not synchronized or buffered in any fashion. Constructed via
51/// the `std::io::stdio::stdout_raw` function.
52struct StdoutRaw(stdio::Stdout);
53
54/// A handle to a raw instance of the standard output stream of this process.
55///
56/// This handle is not synchronized or buffered in any fashion. Constructed via
57/// the `std::io::stdio::stderr_raw` function.
58struct StderrRaw(stdio::Stderr);
59
60/// Constructs a new raw handle to the standard input of this process.
61///
62/// The returned handle does not interact with any other handles created nor
63/// handles returned by `std::io::stdin`. Data buffered by the `std::io::stdin`
64/// handles is **not** available to raw handles returned from this function.
65///
66/// The returned handle has no external synchronization or buffering.
67#[unstable(feature = "libstd_sys_internals", issue = "none")]
68const fn stdin_raw() -> StdinRaw {
69 StdinRaw(stdio::Stdin::new())
70}
71
72/// Constructs a new raw handle to the standard output stream of this process.
73///
74/// The returned handle does not interact with any other handles created nor
75/// handles returned by `std::io::stdout`. Note that data is buffered by the
76/// `std::io::stdout` handles so writes which happen via this raw handle may
77/// appear before previous writes.
78///
79/// The returned handle has no external synchronization or buffering layered on
80/// top.
81#[unstable(feature = "libstd_sys_internals", issue = "none")]
82const fn stdout_raw() -> StdoutRaw {
83 StdoutRaw(stdio::Stdout::new())
84}
85
86/// Constructs a new raw handle to the standard error stream of this process.
87///
88/// The returned handle does not interact with any other handles created nor
89/// handles returned by `std::io::stderr`.
90///
91/// The returned handle has no external synchronization or buffering layered on
92/// top.
93#[unstable(feature = "libstd_sys_internals", issue = "none")]
94const fn stderr_raw() -> StderrRaw {
95 StderrRaw(stdio::Stderr::new())
96}
97
98impl Read for StdinRaw {
99 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
100 handle_ebadf(self.0.read(buf), || Ok(0))
101 }
102
103 fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
104 handle_ebadf(self.0.read_buf(buf), || Ok(()))
105 }
106
107 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
108 handle_ebadf(self.0.read_vectored(bufs), || Ok(0))
109 }
110
111 #[inline]
112 fn is_read_vectored(&self) -> bool {
113 self.0.is_read_vectored()
114 }
115
116 fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
117 if buf.is_empty() {
118 return Ok(());
119 }
120 handle_ebadf(self.0.read_exact(buf), || Err(io::Error::READ_EXACT_EOF))
121 }
122
123 fn read_buf_exact(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
124 if buf.capacity() == 0 {
125 return Ok(());
126 }
127 handle_ebadf(self.0.read_buf_exact(buf), || Err(io::Error::READ_EXACT_EOF))
128 }
129
130 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
131 handle_ebadf(self.0.read_to_end(buf), || Ok(0))
132 }
133
134 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
135 handle_ebadf(self.0.read_to_string(buf), || Ok(0))
136 }
137}
138
139impl Write for StdoutRaw {
140 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
141 handle_ebadf(self.0.write(buf), || Ok(buf.len()))
142 }
143
144 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
145 let total = || Ok(bufs.iter().map(|b| b.len()).sum());
146 handle_ebadf(self.0.write_vectored(bufs), total)
147 }
148
149 #[inline]
150 fn is_write_vectored(&self) -> bool {
151 self.0.is_write_vectored()
152 }
153
154 fn flush(&mut self) -> io::Result<()> {
155 handle_ebadf(self.0.flush(), || Ok(()))
156 }
157
158 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
159 handle_ebadf(self.0.write_all(buf), || Ok(()))
160 }
161
162 fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
163 handle_ebadf(self.0.write_all_vectored(bufs), || Ok(()))
164 }
165
166 fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
167 handle_ebadf(self.0.write_fmt(fmt), || Ok(()))
168 }
169}
170
171impl Write for StderrRaw {
172 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
173 handle_ebadf(self.0.write(buf), || Ok(buf.len()))
174 }
175
176 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
177 let total = || Ok(bufs.iter().map(|b| b.len()).sum());
178 handle_ebadf(self.0.write_vectored(bufs), total)
179 }
180
181 #[inline]
182 fn is_write_vectored(&self) -> bool {
183 self.0.is_write_vectored()
184 }
185
186 fn flush(&mut self) -> io::Result<()> {
187 handle_ebadf(self.0.flush(), || Ok(()))
188 }
189
190 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
191 handle_ebadf(self.0.write_all(buf), || Ok(()))
192 }
193
194 fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
195 handle_ebadf(self.0.write_all_vectored(bufs), || Ok(()))
196 }
197
198 fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
199 handle_ebadf(self.0.write_fmt(fmt), || Ok(()))
200 }
201}
202
203fn handle_ebadf<T>(r: io::Result<T>, default: impl FnOnce() -> io::Result<T>) -> io::Result<T> {
204 match r {
205 Err(ref e: &Error) if stdio::is_ebadf(err:e) => default(),
206 r: Result => r,
207 }
208}
209
210/// A handle to the standard input stream of a process.
211///
212/// Each handle is a shared reference to a global buffer of input data to this
213/// process. A handle can be `lock`'d to gain full access to [`BufRead`] methods
214/// (e.g., `.lines()`). Reads to this handle are otherwise locked with respect
215/// to other reads.
216///
217/// This handle implements the `Read` trait, but beware that concurrent reads
218/// of `Stdin` must be executed with care.
219///
220/// Created by the [`io::stdin`] method.
221///
222/// [`io::stdin`]: stdin
223///
224/// ### Note: Windows Portability Considerations
225///
226/// When operating in a console, the Windows implementation of this stream does not support
227/// non-UTF-8 byte sequences. Attempting to read bytes that are not valid UTF-8 will return
228/// an error.
229///
230/// In a process with a detached console, such as one using
231/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
232/// the contained handle will be null. In such cases, the standard library's `Read` and
233/// `Write` will do nothing and silently succeed. All other I/O operations, via the
234/// standard library or via raw Windows API calls, will fail.
235///
236/// # Examples
237///
238/// ```no_run
239/// use std::io;
240///
241/// fn main() -> io::Result<()> {
242/// let mut buffer = String::new();
243/// let stdin = io::stdin(); // We get `Stdin` here.
244/// stdin.read_line(&mut buffer)?;
245/// Ok(())
246/// }
247/// ```
248#[stable(feature = "rust1", since = "1.0.0")]
249#[cfg_attr(not(test), rustc_diagnostic_item = "Stdin")]
250pub struct Stdin {
251 inner: &'static Mutex<BufReader<StdinRaw>>,
252}
253
254/// A locked reference to the [`Stdin`] handle.
255///
256/// This handle implements both the [`Read`] and [`BufRead`] traits, and
257/// is constructed via the [`Stdin::lock`] method.
258///
259/// ### Note: Windows Portability Considerations
260///
261/// When operating in a console, the Windows implementation of this stream does not support
262/// non-UTF-8 byte sequences. Attempting to read bytes that are not valid UTF-8 will return
263/// an error.
264///
265/// In a process with a detached console, such as one using
266/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
267/// the contained handle will be null. In such cases, the standard library's `Read` and
268/// `Write` will do nothing and silently succeed. All other I/O operations, via the
269/// standard library or via raw Windows API calls, will fail.
270///
271/// # Examples
272///
273/// ```no_run
274/// use std::io::{self, BufRead};
275///
276/// fn main() -> io::Result<()> {
277/// let mut buffer = String::new();
278/// let stdin = io::stdin(); // We get `Stdin` here.
279/// {
280/// let mut handle = stdin.lock(); // We get `StdinLock` here.
281/// handle.read_line(&mut buffer)?;
282/// } // `StdinLock` is dropped here.
283/// Ok(())
284/// }
285/// ```
286#[must_use = "if unused stdin will immediately unlock"]
287#[stable(feature = "rust1", since = "1.0.0")]
288pub struct StdinLock<'a> {
289 inner: MutexGuard<'a, BufReader<StdinRaw>>,
290}
291
292/// Constructs a new handle to the standard input of the current process.
293///
294/// Each handle returned is a reference to a shared global buffer whose access
295/// is synchronized via a mutex. If you need more explicit control over
296/// locking, see the [`Stdin::lock`] method.
297///
298/// ### Note: Windows Portability Considerations
299///
300/// When operating in a console, the Windows implementation of this stream does not support
301/// non-UTF-8 byte sequences. Attempting to read bytes that are not valid UTF-8 will return
302/// an error.
303///
304/// In a process with a detached console, such as one using
305/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
306/// the contained handle will be null. In such cases, the standard library's `Read` and
307/// `Write` will do nothing and silently succeed. All other I/O operations, via the
308/// standard library or via raw Windows API calls, will fail.
309///
310/// # Examples
311///
312/// Using implicit synchronization:
313///
314/// ```no_run
315/// use std::io;
316///
317/// fn main() -> io::Result<()> {
318/// let mut buffer = String::new();
319/// io::stdin().read_line(&mut buffer)?;
320/// Ok(())
321/// }
322/// ```
323///
324/// Using explicit synchronization:
325///
326/// ```no_run
327/// use std::io::{self, BufRead};
328///
329/// fn main() -> io::Result<()> {
330/// let mut buffer = String::new();
331/// let stdin = io::stdin();
332/// let mut handle = stdin.lock();
333///
334/// handle.read_line(&mut buffer)?;
335/// Ok(())
336/// }
337/// ```
338#[must_use]
339#[stable(feature = "rust1", since = "1.0.0")]
340pub fn stdin() -> Stdin {
341 static INSTANCE: OnceLock<Mutex<BufReader<StdinRaw>>> = OnceLock::new();
342 Stdin {
343 inner: INSTANCE.get_or_init(|| {
344 Mutex::new(BufReader::with_capacity(capacity:stdio::STDIN_BUF_SIZE, inner:stdin_raw()))
345 }),
346 }
347}
348
349impl Stdin {
350 /// Locks this handle to the standard input stream, returning a readable
351 /// guard.
352 ///
353 /// The lock is released when the returned lock goes out of scope. The
354 /// returned guard also implements the [`Read`] and [`BufRead`] traits for
355 /// accessing the underlying data.
356 ///
357 /// # Examples
358 ///
359 /// ```no_run
360 /// use std::io::{self, BufRead};
361 ///
362 /// fn main() -> io::Result<()> {
363 /// let mut buffer = String::new();
364 /// let stdin = io::stdin();
365 /// let mut handle = stdin.lock();
366 ///
367 /// handle.read_line(&mut buffer)?;
368 /// Ok(())
369 /// }
370 /// ```
371 #[stable(feature = "rust1", since = "1.0.0")]
372 pub fn lock(&self) -> StdinLock<'static> {
373 // Locks this handle with 'static lifetime. This depends on the
374 // implementation detail that the underlying `Mutex` is static.
375 StdinLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) }
376 }
377
378 /// Locks this handle and reads a line of input, appending it to the specified buffer.
379 ///
380 /// For detailed semantics of this method, see the documentation on
381 /// [`BufRead::read_line`]. In particular:
382 /// * Previous content of the buffer will be preserved. To avoid appending
383 /// to the buffer, you need to [`clear`] it first.
384 /// * The trailing newline character, if any, is included in the buffer.
385 ///
386 /// [`clear`]: String::clear
387 ///
388 /// # Examples
389 ///
390 /// ```no_run
391 /// use std::io;
392 ///
393 /// let mut input = String::new();
394 /// match io::stdin().read_line(&mut input) {
395 /// Ok(n) => {
396 /// println!("{n} bytes read");
397 /// println!("{input}");
398 /// }
399 /// Err(error) => println!("error: {error}"),
400 /// }
401 /// ```
402 ///
403 /// You can run the example one of two ways:
404 ///
405 /// - Pipe some text to it, e.g., `printf foo | path/to/executable`
406 /// - Give it text interactively by running the executable directly,
407 /// in which case it will wait for the Enter key to be pressed before
408 /// continuing
409 #[stable(feature = "rust1", since = "1.0.0")]
410 #[rustc_confusables("get_line")]
411 pub fn read_line(&self, buf: &mut String) -> io::Result<usize> {
412 self.lock().read_line(buf)
413 }
414
415 /// Consumes this handle and returns an iterator over input lines.
416 ///
417 /// For detailed semantics of this method, see the documentation on
418 /// [`BufRead::lines`].
419 ///
420 /// # Examples
421 ///
422 /// ```no_run
423 /// use std::io;
424 ///
425 /// let lines = io::stdin().lines();
426 /// for line in lines {
427 /// println!("got a line: {}", line.unwrap());
428 /// }
429 /// ```
430 #[must_use = "`self` will be dropped if the result is not used"]
431 #[stable(feature = "stdin_forwarders", since = "1.62.0")]
432 pub fn lines(self) -> Lines<StdinLock<'static>> {
433 self.lock().lines()
434 }
435}
436
437#[stable(feature = "std_debug", since = "1.16.0")]
438impl fmt::Debug for Stdin {
439 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
440 f.debug_struct(name:"Stdin").finish_non_exhaustive()
441 }
442}
443
444#[stable(feature = "rust1", since = "1.0.0")]
445impl Read for Stdin {
446 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
447 self.lock().read(buf)
448 }
449 fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
450 self.lock().read_buf(buf)
451 }
452 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
453 self.lock().read_vectored(bufs)
454 }
455 #[inline]
456 fn is_read_vectored(&self) -> bool {
457 self.lock().is_read_vectored()
458 }
459 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
460 self.lock().read_to_end(buf)
461 }
462 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
463 self.lock().read_to_string(buf)
464 }
465 fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
466 self.lock().read_exact(buf)
467 }
468 fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
469 self.lock().read_buf_exact(cursor)
470 }
471}
472
473#[stable(feature = "read_shared_stdin", since = "1.78.0")]
474impl Read for &Stdin {
475 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
476 self.lock().read(buf)
477 }
478 fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
479 self.lock().read_buf(buf)
480 }
481 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
482 self.lock().read_vectored(bufs)
483 }
484 #[inline]
485 fn is_read_vectored(&self) -> bool {
486 self.lock().is_read_vectored()
487 }
488 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
489 self.lock().read_to_end(buf)
490 }
491 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
492 self.lock().read_to_string(buf)
493 }
494 fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
495 self.lock().read_exact(buf)
496 }
497 fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
498 self.lock().read_buf_exact(cursor)
499 }
500}
501
502// only used by platform-dependent io::copy specializations, i.e. unused on some platforms
503#[cfg(any(target_os = "linux", target_os = "android"))]
504impl StdinLock<'_> {
505 pub(crate) fn as_mut_buf(&mut self) -> &mut BufReader<impl Read> {
506 &mut self.inner
507 }
508}
509
510#[stable(feature = "rust1", since = "1.0.0")]
511impl Read for StdinLock<'_> {
512 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
513 self.inner.read(buf)
514 }
515
516 fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
517 self.inner.read_buf(buf)
518 }
519
520 fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
521 self.inner.read_vectored(bufs)
522 }
523
524 #[inline]
525 fn is_read_vectored(&self) -> bool {
526 self.inner.is_read_vectored()
527 }
528
529 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
530 self.inner.read_to_end(buf)
531 }
532
533 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
534 self.inner.read_to_string(buf)
535 }
536
537 fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
538 self.inner.read_exact(buf)
539 }
540
541 fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
542 self.inner.read_buf_exact(cursor)
543 }
544}
545
546impl SpecReadByte for StdinLock<'_> {
547 #[inline]
548 fn spec_read_byte(&mut self) -> Option<io::Result<u8>> {
549 BufReader::spec_read_byte(&mut *self.inner)
550 }
551}
552
553#[stable(feature = "rust1", since = "1.0.0")]
554impl BufRead for StdinLock<'_> {
555 fn fill_buf(&mut self) -> io::Result<&[u8]> {
556 self.inner.fill_buf()
557 }
558
559 fn consume(&mut self, n: usize) {
560 self.inner.consume(amount:n)
561 }
562
563 fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
564 self.inner.read_until(byte, buf)
565 }
566
567 fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
568 self.inner.read_line(buf)
569 }
570}
571
572#[stable(feature = "std_debug", since = "1.16.0")]
573impl fmt::Debug for StdinLock<'_> {
574 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
575 f.debug_struct(name:"StdinLock").finish_non_exhaustive()
576 }
577}
578
579/// A handle to the global standard output stream of the current process.
580///
581/// Each handle shares a global buffer of data to be written to the standard
582/// output stream. Access is also synchronized via a lock and explicit control
583/// over locking is available via the [`lock`] method.
584///
585/// By default, the handle is line-buffered when connected to a terminal, meaning
586/// it flushes automatically when a newline (`\n`) is encountered. For immediate
587/// output, you can manually call the [`flush`] method. When the handle goes out
588/// of scope, the buffer is automatically flushed.
589///
590/// Created by the [`io::stdout`] method.
591///
592/// ### Note: Windows Portability Considerations
593///
594/// When operating in a console, the Windows implementation of this stream does not support
595/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
596/// an error.
597///
598/// In a process with a detached console, such as one using
599/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
600/// the contained handle will be null. In such cases, the standard library's `Read` and
601/// `Write` will do nothing and silently succeed. All other I/O operations, via the
602/// standard library or via raw Windows API calls, will fail.
603///
604/// [`lock`]: Stdout::lock
605/// [`flush`]: Write::flush
606/// [`io::stdout`]: stdout
607#[stable(feature = "rust1", since = "1.0.0")]
608pub struct Stdout {
609 // FIXME: this should be LineWriter or BufWriter depending on the state of
610 // stdout (tty or not). Note that if this is not line buffered it
611 // should also flush-on-panic or some form of flush-on-abort.
612 inner: &'static ReentrantLock<RefCell<LineWriter<StdoutRaw>>>,
613}
614
615/// A locked reference to the [`Stdout`] handle.
616///
617/// This handle implements the [`Write`] trait, and is constructed via
618/// the [`Stdout::lock`] method. See its documentation for more.
619///
620/// By default, the handle is line-buffered when connected to a terminal, meaning
621/// it flushes automatically when a newline (`\n`) is encountered. For immediate
622/// output, you can manually call the [`flush`] method. When the handle goes out
623/// of scope, the buffer is automatically flushed.
624///
625/// ### Note: Windows Portability Considerations
626///
627/// When operating in a console, the Windows implementation of this stream does not support
628/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
629/// an error.
630///
631/// In a process with a detached console, such as one using
632/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
633/// the contained handle will be null. In such cases, the standard library's `Read` and
634/// `Write` will do nothing and silently succeed. All other I/O operations, via the
635/// standard library or via raw Windows API calls, will fail.
636///
637/// [`flush`]: Write::flush
638#[must_use = "if unused stdout will immediately unlock"]
639#[stable(feature = "rust1", since = "1.0.0")]
640pub struct StdoutLock<'a> {
641 inner: ReentrantLockGuard<'a, RefCell<LineWriter<StdoutRaw>>>,
642}
643
644static STDOUT: OnceLock<ReentrantLock<RefCell<LineWriter<StdoutRaw>>>> = OnceLock::new();
645
646/// Constructs a new handle to the standard output of the current process.
647///
648/// Each handle returned is a reference to a shared global buffer whose access
649/// is synchronized via a mutex. If you need more explicit control over
650/// locking, see the [`Stdout::lock`] method.
651///
652/// By default, the handle is line-buffered when connected to a terminal, meaning
653/// it flushes automatically when a newline (`\n`) is encountered. For immediate
654/// output, you can manually call the [`flush`] method. When the handle goes out
655/// of scope, the buffer is automatically flushed.
656///
657/// ### Note: Windows Portability Considerations
658///
659/// When operating in a console, the Windows implementation of this stream does not support
660/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
661/// an error.
662///
663/// In a process with a detached console, such as one using
664/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
665/// the contained handle will be null. In such cases, the standard library's `Read` and
666/// `Write` will do nothing and silently succeed. All other I/O operations, via the
667/// standard library or via raw Windows API calls, will fail.
668///
669/// # Examples
670///
671/// Using implicit synchronization:
672///
673/// ```no_run
674/// use std::io::{self, Write};
675///
676/// fn main() -> io::Result<()> {
677/// io::stdout().write_all(b"hello world")?;
678///
679/// Ok(())
680/// }
681/// ```
682///
683/// Using explicit synchronization:
684///
685/// ```no_run
686/// use std::io::{self, Write};
687///
688/// fn main() -> io::Result<()> {
689/// let stdout = io::stdout();
690/// let mut handle = stdout.lock();
691///
692/// handle.write_all(b"hello world")?;
693///
694/// Ok(())
695/// }
696/// ```
697///
698/// Ensuring output is flushed immediately:
699///
700/// ```no_run
701/// use std::io::{self, Write};
702///
703/// fn main() -> io::Result<()> {
704/// let mut stdout = io::stdout();
705/// stdout.write_all(b"hello, ")?;
706/// stdout.flush()?; // Manual flush
707/// stdout.write_all(b"world!\n")?; // Automatically flushed
708/// Ok(())
709/// }
710/// ```
711///
712/// [`flush`]: Write::flush
713#[must_use]
714#[stable(feature = "rust1", since = "1.0.0")]
715#[cfg_attr(not(test), rustc_diagnostic_item = "io_stdout")]
716pub fn stdout() -> Stdout {
717 Stdout {
718 inner: STDOUTOnceLock>>
719 .get_or_init(|| ReentrantLock::new(RefCell::new(LineWriter::new(inner:stdout_raw())))),
720 }
721}
722
723// Flush the data and disable buffering during shutdown
724// by replacing the line writer by one with zero
725// buffering capacity.
726pub fn cleanup() {
727 let mut initialized: bool = false;
728 let stdout: &ReentrantLock>> = STDOUT.get_or_init(|| {
729 initialized = true;
730 ReentrantLock::new(RefCell::new(LineWriter::with_capacity(capacity:0, inner:stdout_raw())))
731 });
732
733 if !initialized {
734 // The buffer was previously initialized, overwrite it here.
735 // We use try_lock() instead of lock(), because someone
736 // might have leaked a StdoutLock, which would
737 // otherwise cause a deadlock here.
738 if let Some(lock: ReentrantLockGuard<'_, RefCell<…>>) = stdout.try_lock() {
739 *lock.borrow_mut() = LineWriter::with_capacity(capacity:0, inner:stdout_raw());
740 }
741 }
742}
743
744impl Stdout {
745 /// Locks this handle to the standard output stream, returning a writable
746 /// guard.
747 ///
748 /// The lock is released when the returned lock goes out of scope. The
749 /// returned guard also implements the `Write` trait for writing data.
750 ///
751 /// # Examples
752 ///
753 /// ```no_run
754 /// use std::io::{self, Write};
755 ///
756 /// fn main() -> io::Result<()> {
757 /// let mut stdout = io::stdout().lock();
758 ///
759 /// stdout.write_all(b"hello world")?;
760 ///
761 /// Ok(())
762 /// }
763 /// ```
764 #[stable(feature = "rust1", since = "1.0.0")]
765 pub fn lock(&self) -> StdoutLock<'static> {
766 // Locks this handle with 'static lifetime. This depends on the
767 // implementation detail that the underlying `ReentrantMutex` is
768 // static.
769 StdoutLock { inner: self.inner.lock() }
770 }
771}
772
773#[stable(feature = "catch_unwind", since = "1.9.0")]
774impl UnwindSafe for Stdout {}
775
776#[stable(feature = "catch_unwind", since = "1.9.0")]
777impl RefUnwindSafe for Stdout {}
778
779#[stable(feature = "std_debug", since = "1.16.0")]
780impl fmt::Debug for Stdout {
781 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
782 f.debug_struct(name:"Stdout").finish_non_exhaustive()
783 }
784}
785
786#[stable(feature = "rust1", since = "1.0.0")]
787impl Write for Stdout {
788 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
789 (&*self).write(buf)
790 }
791 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
792 (&*self).write_vectored(bufs)
793 }
794 #[inline]
795 fn is_write_vectored(&self) -> bool {
796 io::Write::is_write_vectored(&&*self)
797 }
798 fn flush(&mut self) -> io::Result<()> {
799 (&*self).flush()
800 }
801 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
802 (&*self).write_all(buf)
803 }
804 fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
805 (&*self).write_all_vectored(bufs)
806 }
807 fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> {
808 (&*self).write_fmt(args)
809 }
810}
811
812#[stable(feature = "write_mt", since = "1.48.0")]
813impl Write for &Stdout {
814 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
815 self.lock().write(buf)
816 }
817 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
818 self.lock().write_vectored(bufs)
819 }
820 #[inline]
821 fn is_write_vectored(&self) -> bool {
822 self.lock().is_write_vectored()
823 }
824 fn flush(&mut self) -> io::Result<()> {
825 self.lock().flush()
826 }
827 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
828 self.lock().write_all(buf)
829 }
830 fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
831 self.lock().write_all_vectored(bufs)
832 }
833 fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> {
834 self.lock().write_fmt(args)
835 }
836}
837
838#[stable(feature = "catch_unwind", since = "1.9.0")]
839impl UnwindSafe for StdoutLock<'_> {}
840
841#[stable(feature = "catch_unwind", since = "1.9.0")]
842impl RefUnwindSafe for StdoutLock<'_> {}
843
844#[stable(feature = "rust1", since = "1.0.0")]
845impl Write for StdoutLock<'_> {
846 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
847 self.inner.borrow_mut().write(buf)
848 }
849 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
850 self.inner.borrow_mut().write_vectored(bufs)
851 }
852 #[inline]
853 fn is_write_vectored(&self) -> bool {
854 self.inner.borrow_mut().is_write_vectored()
855 }
856 fn flush(&mut self) -> io::Result<()> {
857 self.inner.borrow_mut().flush()
858 }
859 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
860 self.inner.borrow_mut().write_all(buf)
861 }
862 fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
863 self.inner.borrow_mut().write_all_vectored(bufs)
864 }
865}
866
867#[stable(feature = "std_debug", since = "1.16.0")]
868impl fmt::Debug for StdoutLock<'_> {
869 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
870 f.debug_struct(name:"StdoutLock").finish_non_exhaustive()
871 }
872}
873
874/// A handle to the standard error stream of a process.
875///
876/// For more information, see the [`io::stderr`] method.
877///
878/// [`io::stderr`]: stderr
879///
880/// ### Note: Windows Portability Considerations
881///
882/// When operating in a console, the Windows implementation of this stream does not support
883/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
884/// an error.
885///
886/// In a process with a detached console, such as one using
887/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
888/// the contained handle will be null. In such cases, the standard library's `Read` and
889/// `Write` will do nothing and silently succeed. All other I/O operations, via the
890/// standard library or via raw Windows API calls, will fail.
891#[stable(feature = "rust1", since = "1.0.0")]
892pub struct Stderr {
893 inner: &'static ReentrantLock<RefCell<StderrRaw>>,
894}
895
896/// A locked reference to the [`Stderr`] handle.
897///
898/// This handle implements the [`Write`] trait and is constructed via
899/// the [`Stderr::lock`] method. See its documentation for more.
900///
901/// ### Note: Windows Portability Considerations
902///
903/// When operating in a console, the Windows implementation of this stream does not support
904/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
905/// an error.
906///
907/// In a process with a detached console, such as one using
908/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
909/// the contained handle will be null. In such cases, the standard library's `Read` and
910/// `Write` will do nothing and silently succeed. All other I/O operations, via the
911/// standard library or via raw Windows API calls, will fail.
912#[must_use = "if unused stderr will immediately unlock"]
913#[stable(feature = "rust1", since = "1.0.0")]
914pub struct StderrLock<'a> {
915 inner: ReentrantLockGuard<'a, RefCell<StderrRaw>>,
916}
917
918/// Constructs a new handle to the standard error of the current process.
919///
920/// This handle is not buffered.
921///
922/// ### Note: Windows Portability Considerations
923///
924/// When operating in a console, the Windows implementation of this stream does not support
925/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
926/// an error.
927///
928/// In a process with a detached console, such as one using
929/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
930/// the contained handle will be null. In such cases, the standard library's `Read` and
931/// `Write` will do nothing and silently succeed. All other I/O operations, via the
932/// standard library or via raw Windows API calls, will fail.
933///
934/// # Examples
935///
936/// Using implicit synchronization:
937///
938/// ```no_run
939/// use std::io::{self, Write};
940///
941/// fn main() -> io::Result<()> {
942/// io::stderr().write_all(b"hello world")?;
943///
944/// Ok(())
945/// }
946/// ```
947///
948/// Using explicit synchronization:
949///
950/// ```no_run
951/// use std::io::{self, Write};
952///
953/// fn main() -> io::Result<()> {
954/// let stderr = io::stderr();
955/// let mut handle = stderr.lock();
956///
957/// handle.write_all(b"hello world")?;
958///
959/// Ok(())
960/// }
961/// ```
962#[must_use]
963#[stable(feature = "rust1", since = "1.0.0")]
964#[cfg_attr(not(test), rustc_diagnostic_item = "io_stderr")]
965pub fn stderr() -> Stderr {
966 // Note that unlike `stdout()` we don't use `at_exit` here to register a
967 // destructor. Stderr is not buffered, so there's no need to run a
968 // destructor for flushing the buffer
969 static INSTANCE: ReentrantLock<RefCell<StderrRaw>> =
970 ReentrantLock::new(RefCell::new(stderr_raw()));
971
972 Stderr { inner: &INSTANCE }
973}
974
975impl Stderr {
976 /// Locks this handle to the standard error stream, returning a writable
977 /// guard.
978 ///
979 /// The lock is released when the returned lock goes out of scope. The
980 /// returned guard also implements the [`Write`] trait for writing data.
981 ///
982 /// # Examples
983 ///
984 /// ```
985 /// use std::io::{self, Write};
986 ///
987 /// fn foo() -> io::Result<()> {
988 /// let stderr = io::stderr();
989 /// let mut handle = stderr.lock();
990 ///
991 /// handle.write_all(b"hello world")?;
992 ///
993 /// Ok(())
994 /// }
995 /// ```
996 #[stable(feature = "rust1", since = "1.0.0")]
997 pub fn lock(&self) -> StderrLock<'static> {
998 // Locks this handle with 'static lifetime. This depends on the
999 // implementation detail that the underlying `ReentrantMutex` is
1000 // static.
1001 StderrLock { inner: self.inner.lock() }
1002 }
1003}
1004
1005#[stable(feature = "catch_unwind", since = "1.9.0")]
1006impl UnwindSafe for Stderr {}
1007
1008#[stable(feature = "catch_unwind", since = "1.9.0")]
1009impl RefUnwindSafe for Stderr {}
1010
1011#[stable(feature = "std_debug", since = "1.16.0")]
1012impl fmt::Debug for Stderr {
1013 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1014 f.debug_struct(name:"Stderr").finish_non_exhaustive()
1015 }
1016}
1017
1018#[stable(feature = "rust1", since = "1.0.0")]
1019impl Write for Stderr {
1020 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
1021 (&*self).write(buf)
1022 }
1023 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
1024 (&*self).write_vectored(bufs)
1025 }
1026 #[inline]
1027 fn is_write_vectored(&self) -> bool {
1028 io::Write::is_write_vectored(&&*self)
1029 }
1030 fn flush(&mut self) -> io::Result<()> {
1031 (&*self).flush()
1032 }
1033 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
1034 (&*self).write_all(buf)
1035 }
1036 fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
1037 (&*self).write_all_vectored(bufs)
1038 }
1039 fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> {
1040 (&*self).write_fmt(args)
1041 }
1042}
1043
1044#[stable(feature = "write_mt", since = "1.48.0")]
1045impl Write for &Stderr {
1046 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
1047 self.lock().write(buf)
1048 }
1049 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
1050 self.lock().write_vectored(bufs)
1051 }
1052 #[inline]
1053 fn is_write_vectored(&self) -> bool {
1054 self.lock().is_write_vectored()
1055 }
1056 fn flush(&mut self) -> io::Result<()> {
1057 self.lock().flush()
1058 }
1059 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
1060 self.lock().write_all(buf)
1061 }
1062 fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
1063 self.lock().write_all_vectored(bufs)
1064 }
1065 fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> {
1066 self.lock().write_fmt(args)
1067 }
1068}
1069
1070#[stable(feature = "catch_unwind", since = "1.9.0")]
1071impl UnwindSafe for StderrLock<'_> {}
1072
1073#[stable(feature = "catch_unwind", since = "1.9.0")]
1074impl RefUnwindSafe for StderrLock<'_> {}
1075
1076#[stable(feature = "rust1", since = "1.0.0")]
1077impl Write for StderrLock<'_> {
1078 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
1079 self.inner.borrow_mut().write(buf)
1080 }
1081 fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
1082 self.inner.borrow_mut().write_vectored(bufs)
1083 }
1084 #[inline]
1085 fn is_write_vectored(&self) -> bool {
1086 self.inner.borrow_mut().is_write_vectored()
1087 }
1088 fn flush(&mut self) -> io::Result<()> {
1089 self.inner.borrow_mut().flush()
1090 }
1091 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
1092 self.inner.borrow_mut().write_all(buf)
1093 }
1094 fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
1095 self.inner.borrow_mut().write_all_vectored(bufs)
1096 }
1097}
1098
1099#[stable(feature = "std_debug", since = "1.16.0")]
1100impl fmt::Debug for StderrLock<'_> {
1101 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1102 f.debug_struct(name:"StderrLock").finish_non_exhaustive()
1103 }
1104}
1105
1106/// Sets the thread-local output capture buffer and returns the old one.
1107#[unstable(
1108 feature = "internal_output_capture",
1109 reason = "this function is meant for use in the test crate \
1110 and may disappear in the future",
1111 issue = "none"
1112)]
1113#[doc(hidden)]
1114pub fn set_output_capture(sink: Option<LocalStream>) -> Option<LocalStream> {
1115 try_set_output_capture(sink).expect(
1116 msg:"cannot access a Thread Local Storage value \
1117msg: during or after destruction",
1118 )
1119}
1120
1121/// Tries to set the thread-local output capture buffer and returns the old one.
1122/// This may fail once thread-local destructors are called. It's used in panic
1123/// handling instead of `set_output_capture`.
1124#[unstable(
1125 feature = "internal_output_capture",
1126 reason = "this function is meant for use in the test crate \
1127 and may disappear in the future",
1128 issue = "none"
1129)]
1130#[doc(hidden)]
1131pub fn try_set_output_capture(
1132 sink: Option<LocalStream>,
1133) -> Result<Option<LocalStream>, AccessError> {
1134 if sink.is_none() && !OUTPUT_CAPTURE_USED.load(Ordering::Relaxed) {
1135 // OUTPUT_CAPTURE is definitely None since OUTPUT_CAPTURE_USED is false.
1136 return Ok(None);
1137 }
1138 OUTPUT_CAPTURE_USED.store(true, Ordering::Relaxed);
1139 OUTPUT_CAPTURE.try_with(move |slot: &Cell>>>>| slot.replace(val:sink))
1140}
1141
1142/// Writes `args` to the capture buffer if enabled and possible, or `global_s`
1143/// otherwise. `label` identifies the stream in a panic message.
1144///
1145/// This function is used to print error messages, so it takes extra
1146/// care to avoid causing a panic when `OUTPUT_CAPTURE` is unusable.
1147/// For instance, if the TLS key for output capturing is already destroyed, or
1148/// if the local stream is in use by another thread, it will just fall back to
1149/// the global stream.
1150///
1151/// However, if the actual I/O causes an error, this function does panic.
1152///
1153/// Writing to non-blocking stdout/stderr can cause an error, which will lead
1154/// this function to panic.
1155fn print_to<T>(args: fmt::Arguments<'_>, global_s: fn() -> T, label: &str)
1156where
1157 T: Write,
1158{
1159 if print_to_buffer_if_capture_used(args) {
1160 // Successfully wrote to capture buffer.
1161 return;
1162 }
1163
1164 if let Err(e: Error) = global_s().write_fmt(args) {
1165 panic!("failed printing to {label}: {e}");
1166 }
1167}
1168
1169fn print_to_buffer_if_capture_used(args: fmt::Arguments<'_>) -> bool {
1170 OUTPUT_CAPTURE_USED.load(Ordering::Relaxed)
1171 && OUTPUT_CAPTURE.try_with(|s: &Cell>>>>| {
1172 // Note that we completely remove a local sink to write to in case
1173 // our printing recursively panics/prints, so the recursive
1174 // panic/print goes to the global sink instead of our local sink.
1175 s.take().map(|w: Arc>>| {
1176 let _ = w.lock().unwrap_or_else(|e: PoisonError>| e.into_inner()).write_fmt(args);
1177 s.set(val:Some(w));
1178 })
1179 }) == Ok(Some(()))
1180}
1181
1182/// Used by impl Termination for Result to print error after `main` or a test
1183/// has returned. Should avoid panicking, although we can't help it if one of
1184/// the Display impls inside args decides to.
1185pub(crate) fn attempt_print_to_stderr(args: fmt::Arguments<'_>) {
1186 if print_to_buffer_if_capture_used(args) {
1187 return;
1188 }
1189
1190 // Ignore error if the write fails, for example because stderr is already
1191 // closed. There is not much point panicking at this point.
1192 let _ = stderr().write_fmt(args);
1193}
1194
1195/// Trait to determine if a descriptor/handle refers to a terminal/tty.
1196#[stable(feature = "is_terminal", since = "1.70.0")]
1197pub trait IsTerminal: crate::sealed::Sealed {
1198 /// Returns `true` if the descriptor/handle refers to a terminal/tty.
1199 ///
1200 /// On platforms where Rust does not know how to detect a terminal yet, this will return
1201 /// `false`. This will also return `false` if an unexpected error occurred, such as from
1202 /// passing an invalid file descriptor.
1203 ///
1204 /// # Platform-specific behavior
1205 ///
1206 /// On Windows, in addition to detecting consoles, this currently uses some heuristics to
1207 /// detect older msys/cygwin/mingw pseudo-terminals based on device name: devices with names
1208 /// starting with `msys-` or `cygwin-` and ending in `-pty` will be considered terminals.
1209 /// Note that this [may change in the future][changes].
1210 ///
1211 /// # Examples
1212 ///
1213 /// An example of a type for which `IsTerminal` is implemented is [`Stdin`]:
1214 ///
1215 /// ```no_run
1216 /// use std::io::{self, IsTerminal, Write};
1217 ///
1218 /// fn main() -> io::Result<()> {
1219 /// let stdin = io::stdin();
1220 ///
1221 /// // Indicate that the user is prompted for input, if this is a terminal.
1222 /// if stdin.is_terminal() {
1223 /// print!("> ");
1224 /// io::stdout().flush()?;
1225 /// }
1226 ///
1227 /// let mut name = String::new();
1228 /// let _ = stdin.read_line(&mut name)?;
1229 ///
1230 /// println!("Hello {}", name.trim_end());
1231 ///
1232 /// Ok(())
1233 /// }
1234 /// ```
1235 ///
1236 /// The example can be run in two ways:
1237 ///
1238 /// - If you run this example by piping some text to it, e.g. `echo "foo" | path/to/executable`
1239 /// it will print: `Hello foo`.
1240 /// - If you instead run the example interactively by running `path/to/executable` directly, it will
1241 /// prompt for input.
1242 ///
1243 /// [changes]: io#platform-specific-behavior
1244 /// [`Stdin`]: crate::io::Stdin
1245 #[doc(alias = "isatty")]
1246 #[stable(feature = "is_terminal", since = "1.70.0")]
1247 fn is_terminal(&self) -> bool;
1248}
1249
1250macro_rules! impl_is_terminal {
1251 ($($t:ty),*$(,)?) => {$(
1252 #[unstable(feature = "sealed", issue = "none")]
1253 impl crate::sealed::Sealed for $t {}
1254
1255 #[stable(feature = "is_terminal", since = "1.70.0")]
1256 impl IsTerminal for $t {
1257 #[inline]
1258 fn is_terminal(&self) -> bool {
1259 crate::sys::io::is_terminal(self)
1260 }
1261 }
1262 )*}
1263}
1264
1265impl_is_terminal!(File, Stdin, StdinLock<'_>, Stdout, StdoutLock<'_>, Stderr, StderrLock<'_>);
1266
1267#[unstable(
1268 feature = "print_internals",
1269 reason = "implementation detail which may disappear or be replaced at any time",
1270 issue = "none"
1271)]
1272#[doc(hidden)]
1273#[cfg(not(test))]
1274pub fn _print(args: fmt::Arguments<'_>) {
1275 print_to(args, global_s:stdout, label:"stdout");
1276}
1277
1278#[unstable(
1279 feature = "print_internals",
1280 reason = "implementation detail which may disappear or be replaced at any time",
1281 issue = "none"
1282)]
1283#[doc(hidden)]
1284#[cfg(not(test))]
1285pub fn _eprint(args: fmt::Arguments<'_>) {
1286 print_to(args, global_s:stderr, label:"stderr");
1287}
1288
1289#[cfg(test)]
1290pub use realstd::io::{_eprint, _print};
1291