1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
16 use io::{self, Initializer, BufReader, LineWriter};
17 use sync::{Arc, Mutex, MutexGuard};
19 use sys_common::remutex::{ReentrantMutex, ReentrantMutexGuard};
22 /// Stdout used by print! and println! macros
24 static LOCAL_STDOUT: RefCell<Option<Box<dyn Write + Send>>> = {
29 /// A handle to a raw instance of the standard input stream of this process.
31 /// This handle is not synchronized or buffered in any fashion. Constructed via
32 /// the `std::io::stdio::stdin_raw` function.
33 struct StdinRaw(stdio::Stdin);
35 /// A handle to a raw instance of the standard output stream of this process.
37 /// This handle is not synchronized or buffered in any fashion. Constructed via
38 /// the `std::io::stdio::stdout_raw` function.
39 struct StdoutRaw(stdio::Stdout);
41 /// A handle to a raw instance of the standard output stream of this process.
43 /// This handle is not synchronized or buffered in any fashion. Constructed via
44 /// the `std::io::stdio::stderr_raw` function.
45 struct StderrRaw(stdio::Stderr);
47 /// Constructs a new raw handle to the standard input of this process.
49 /// The returned handle does not interact with any other handles created nor
50 /// handles returned by `std::io::stdin`. Data buffered by the `std::io::stdin`
51 /// handles is **not** available to raw handles returned from this function.
53 /// The returned handle has no external synchronization or buffering.
54 fn stdin_raw() -> io::Result<StdinRaw> { stdio::Stdin::new().map(StdinRaw) }
56 /// Constructs a new raw handle to the standard output stream of this process.
58 /// The returned handle does not interact with any other handles created nor
59 /// handles returned by `std::io::stdout`. Note that data is buffered by the
60 /// `std::io::stdout` handles so writes which happen via this raw handle may
61 /// appear before previous writes.
63 /// The returned handle has no external synchronization or buffering layered on
65 fn stdout_raw() -> io::Result<StdoutRaw> { stdio::Stdout::new().map(StdoutRaw) }
67 /// Constructs a new raw handle to the standard error stream of this process.
69 /// The returned handle does not interact with any other handles created nor
70 /// handles returned by `std::io::stderr`.
72 /// The returned handle has no external synchronization or buffering layered on
74 fn stderr_raw() -> io::Result<StderrRaw> { stdio::Stderr::new().map(StderrRaw) }
76 impl Read for StdinRaw {
77 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { self.0.read(buf) }
80 unsafe fn initializer(&self) -> Initializer {
84 impl Write for StdoutRaw {
85 fn write(&mut self, buf: &[u8]) -> io::Result<usize> { self.0.write(buf) }
86 fn flush(&mut self) -> io::Result<()> { self.0.flush() }
88 impl Write for StderrRaw {
89 fn write(&mut self, buf: &[u8]) -> io::Result<usize> { self.0.write(buf) }
90 fn flush(&mut self) -> io::Result<()> { self.0.flush() }
98 impl<W: io::Write> io::Write for Maybe<W> {
99 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
101 Maybe::Real(ref mut w) => handle_ebadf(w.write(buf), buf.len()),
102 Maybe::Fake => Ok(buf.len())
106 fn flush(&mut self) -> io::Result<()> {
108 Maybe::Real(ref mut w) => handle_ebadf(w.flush(), ()),
109 Maybe::Fake => Ok(())
114 impl<R: io::Read> io::Read for Maybe<R> {
115 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
117 Maybe::Real(ref mut r) => handle_ebadf(r.read(buf), 0),
123 fn handle_ebadf<T>(r: io::Result<T>, default: T) -> io::Result<T> {
125 Err(ref e) if stdio::is_ebadf(e) => Ok(default),
130 /// A handle to the standard input stream of a process.
132 /// Each handle is a shared reference to a global buffer of input data to this
133 /// process. A handle can be `lock`'d to gain full access to [`BufRead`] methods
134 /// (e.g. `.lines()`). Reads to this handle are otherwise locked with respect
137 /// This handle implements the `Read` trait, but beware that concurrent reads
138 /// of `Stdin` must be executed with care.
140 /// Created by the [`io::stdin`] method.
142 /// [`io::stdin`]: fn.stdin.html
143 /// [`BufRead`]: trait.BufRead.html
144 #[stable(feature = "rust1", since = "1.0.0")]
146 inner: Arc<Mutex<BufReader<Maybe<StdinRaw>>>>,
149 /// A locked reference to the `Stdin` handle.
151 /// This handle implements both the [`Read`] and [`BufRead`] traits, and
152 /// is constructed via the [`Stdin::lock`] method.
154 /// [`Read`]: trait.Read.html
155 /// [`BufRead`]: trait.BufRead.html
156 /// [`Stdin::lock`]: struct.Stdin.html#method.lock
157 #[stable(feature = "rust1", since = "1.0.0")]
158 pub struct StdinLock<'a> {
159 inner: MutexGuard<'a, BufReader<Maybe<StdinRaw>>>,
162 /// Constructs a new handle to the standard input of the current process.
164 /// Each handle returned is a reference to a shared global buffer whose access
165 /// is synchronized via a mutex. If you need more explicit control over
166 /// locking, see the [`lock() method`][lock].
168 /// [lock]: struct.Stdin.html#method.lock
172 /// Using implicit synchronization:
175 /// use std::io::{self, Read};
177 /// fn main() -> io::Result<()> {
178 /// let mut buffer = String::new();
179 /// io::stdin().read_to_string(&mut buffer)?;
184 /// Using explicit synchronization:
187 /// use std::io::{self, Read};
189 /// fn main() -> io::Result<()> {
190 /// let mut buffer = String::new();
191 /// let stdin = io::stdin();
192 /// let mut handle = stdin.lock();
194 /// handle.read_to_string(&mut buffer)?;
198 #[stable(feature = "rust1", since = "1.0.0")]
199 pub fn stdin() -> Stdin {
200 static INSTANCE: Lazy<Mutex<BufReader<Maybe<StdinRaw>>>> = unsafe { Lazy::new(stdin_init) };
202 inner: INSTANCE.get().expect("cannot access stdin during shutdown"),
205 fn stdin_init() -> Arc<Mutex<BufReader<Maybe<StdinRaw>>>> {
206 // This must not reentrantly access `INSTANCE`
207 let stdin = match stdin_raw() {
208 Ok(stdin) => Maybe::Real(stdin),
212 Arc::new(Mutex::new(BufReader::with_capacity(stdio::STDIN_BUF_SIZE, stdin)))
217 /// Locks this handle to the standard input stream, returning a readable
220 /// The lock is released when the returned lock goes out of scope. The
221 /// returned guard also implements the [`Read`] and [`BufRead`] traits for
222 /// accessing the underlying data.
224 /// [`Read`]: trait.Read.html
225 /// [`BufRead`]: trait.BufRead.html
230 /// use std::io::{self, Read};
232 /// fn main() -> io::Result<()> {
233 /// let mut buffer = String::new();
234 /// let stdin = io::stdin();
235 /// let mut handle = stdin.lock();
237 /// handle.read_to_string(&mut buffer)?;
241 #[stable(feature = "rust1", since = "1.0.0")]
242 pub fn lock(&self) -> StdinLock {
243 StdinLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) }
246 /// Locks this handle and reads a line of input into the specified buffer.
248 /// For detailed semantics of this method, see the documentation on
249 /// [`BufRead::read_line`].
251 /// [`BufRead::read_line`]: trait.BufRead.html#method.read_line
258 /// let mut input = String::new();
259 /// match io::stdin().read_line(&mut input) {
261 /// println!("{} bytes read", n);
262 /// println!("{}", input);
264 /// Err(error) => println!("error: {}", error),
268 /// You can run the example one of two ways:
270 /// - Pipe some text to it, e.g. `printf foo | path/to/executable`
271 /// - Give it text interactively by running the executable directly,
272 /// in which case it will wait for the Enter key to be pressed before
274 #[stable(feature = "rust1", since = "1.0.0")]
275 pub fn read_line(&self, buf: &mut String) -> io::Result<usize> {
276 self.lock().read_line(buf)
280 #[stable(feature = "std_debug", since = "1.16.0")]
281 impl fmt::Debug for Stdin {
282 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
283 f.pad("Stdin { .. }")
287 #[stable(feature = "rust1", since = "1.0.0")]
288 impl Read for Stdin {
289 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
290 self.lock().read(buf)
293 unsafe fn initializer(&self) -> Initializer {
296 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
297 self.lock().read_to_end(buf)
299 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
300 self.lock().read_to_string(buf)
302 fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
303 self.lock().read_exact(buf)
307 #[stable(feature = "rust1", since = "1.0.0")]
308 impl<'a> Read for StdinLock<'a> {
309 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
313 unsafe fn initializer(&self) -> Initializer {
318 #[stable(feature = "rust1", since = "1.0.0")]
319 impl<'a> BufRead for StdinLock<'a> {
320 fn fill_buf(&mut self) -> io::Result<&[u8]> { self.inner.fill_buf() }
321 fn consume(&mut self, n: usize) { self.inner.consume(n) }
324 #[stable(feature = "std_debug", since = "1.16.0")]
325 impl<'a> fmt::Debug for StdinLock<'a> {
326 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
327 f.pad("StdinLock { .. }")
331 /// A handle to the global standard output stream of the current process.
333 /// Each handle shares a global buffer of data to be written to the standard
334 /// output stream. Access is also synchronized via a lock and explicit control
335 /// over locking is available via the [`lock`] method.
337 /// Created by the [`io::stdout`] method.
339 /// [`lock`]: #method.lock
340 /// [`io::stdout`]: fn.stdout.html
341 #[stable(feature = "rust1", since = "1.0.0")]
343 // FIXME: this should be LineWriter or BufWriter depending on the state of
344 // stdout (tty or not). Note that if this is not line buffered it
345 // should also flush-on-panic or some form of flush-on-abort.
346 inner: Arc<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>>,
349 /// A locked reference to the `Stdout` handle.
351 /// This handle implements the [`Write`] trait, and is constructed via
352 /// the [`Stdout::lock`] method.
354 /// [`Write`]: trait.Write.html
355 /// [`Stdout::lock`]: struct.Stdout.html#method.lock
356 #[stable(feature = "rust1", since = "1.0.0")]
357 pub struct StdoutLock<'a> {
358 inner: ReentrantMutexGuard<'a, RefCell<LineWriter<Maybe<StdoutRaw>>>>,
361 /// Constructs a new handle to the standard output of the current process.
363 /// Each handle returned is a reference to a shared global buffer whose access
364 /// is synchronized via a mutex. If you need more explicit control over
365 /// locking, see the [Stdout::lock] method.
367 /// [Stdout::lock]: struct.Stdout.html#method.lock
371 /// Using implicit synchronization:
374 /// use std::io::{self, Write};
376 /// fn main() -> io::Result<()> {
377 /// io::stdout().write(b"hello world")?;
383 /// Using explicit synchronization:
386 /// use std::io::{self, Write};
388 /// fn main() -> io::Result<()> {
389 /// let stdout = io::stdout();
390 /// let mut handle = stdout.lock();
392 /// handle.write(b"hello world")?;
397 #[stable(feature = "rust1", since = "1.0.0")]
398 pub fn stdout() -> Stdout {
399 static INSTANCE: Lazy<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>>
400 = unsafe { Lazy::new(stdout_init) };
402 inner: INSTANCE.get().expect("cannot access stdout during shutdown"),
405 fn stdout_init() -> Arc<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>> {
406 // This must not reentrantly access `INSTANCE`
407 let stdout = match stdout_raw() {
408 Ok(stdout) => Maybe::Real(stdout),
411 Arc::new(ReentrantMutex::new(RefCell::new(LineWriter::new(stdout))))
416 /// Locks this handle to the standard output stream, returning a writable
419 /// The lock is released when the returned lock goes out of scope. The
420 /// returned guard also implements the `Write` trait for writing data.
425 /// use std::io::{self, Write};
427 /// fn main() -> io::Result<()> {
428 /// let stdout = io::stdout();
429 /// let mut handle = stdout.lock();
431 /// handle.write(b"hello world")?;
436 #[stable(feature = "rust1", since = "1.0.0")]
437 pub fn lock(&self) -> StdoutLock {
438 StdoutLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) }
442 #[stable(feature = "std_debug", since = "1.16.0")]
443 impl fmt::Debug for Stdout {
444 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
445 f.pad("Stdout { .. }")
449 #[stable(feature = "rust1", since = "1.0.0")]
450 impl Write for Stdout {
451 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
452 self.lock().write(buf)
454 fn flush(&mut self) -> io::Result<()> {
457 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
458 self.lock().write_all(buf)
460 fn write_fmt(&mut self, args: fmt::Arguments) -> io::Result<()> {
461 self.lock().write_fmt(args)
464 #[stable(feature = "rust1", since = "1.0.0")]
465 impl<'a> Write for StdoutLock<'a> {
466 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
467 self.inner.borrow_mut().write(buf)
469 fn flush(&mut self) -> io::Result<()> {
470 self.inner.borrow_mut().flush()
474 #[stable(feature = "std_debug", since = "1.16.0")]
475 impl<'a> fmt::Debug for StdoutLock<'a> {
476 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
477 f.pad("StdoutLock { .. }")
481 /// A handle to the standard error stream of a process.
483 /// For more information, see the [`io::stderr`] method.
485 /// [`io::stderr`]: fn.stderr.html
486 #[stable(feature = "rust1", since = "1.0.0")]
488 inner: Arc<ReentrantMutex<RefCell<Maybe<StderrRaw>>>>,
491 /// A locked reference to the `Stderr` handle.
493 /// This handle implements the `Write` trait and is constructed via
494 /// the [`Stderr::lock`] method.
496 /// [`Stderr::lock`]: struct.Stderr.html#method.lock
497 #[stable(feature = "rust1", since = "1.0.0")]
498 pub struct StderrLock<'a> {
499 inner: ReentrantMutexGuard<'a, RefCell<Maybe<StderrRaw>>>,
502 /// Constructs a new handle to the standard error of the current process.
504 /// This handle is not buffered.
508 /// Using implicit synchronization:
511 /// use std::io::{self, Write};
513 /// fn main() -> io::Result<()> {
514 /// io::stderr().write(b"hello world")?;
520 /// Using explicit synchronization:
523 /// use std::io::{self, Write};
525 /// fn main() -> io::Result<()> {
526 /// let stderr = io::stderr();
527 /// let mut handle = stderr.lock();
529 /// handle.write(b"hello world")?;
534 #[stable(feature = "rust1", since = "1.0.0")]
535 pub fn stderr() -> Stderr {
536 static INSTANCE: Lazy<ReentrantMutex<RefCell<Maybe<StderrRaw>>>> =
537 unsafe { Lazy::new(stderr_init) };
539 inner: INSTANCE.get().expect("cannot access stderr during shutdown"),
542 fn stderr_init() -> Arc<ReentrantMutex<RefCell<Maybe<StderrRaw>>>> {
543 // This must not reentrantly access `INSTANCE`
544 let stderr = match stderr_raw() {
545 Ok(stderr) => Maybe::Real(stderr),
548 Arc::new(ReentrantMutex::new(RefCell::new(stderr)))
553 /// Locks this handle to the standard error stream, returning a writable
556 /// The lock is released when the returned lock goes out of scope. The
557 /// returned guard also implements the `Write` trait for writing data.
562 /// use std::io::{self, Write};
564 /// fn foo() -> io::Result<()> {
565 /// let stderr = io::stderr();
566 /// let mut handle = stderr.lock();
568 /// handle.write(b"hello world")?;
573 #[stable(feature = "rust1", since = "1.0.0")]
574 pub fn lock(&self) -> StderrLock {
575 StderrLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) }
579 #[stable(feature = "std_debug", since = "1.16.0")]
580 impl fmt::Debug for Stderr {
581 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
582 f.pad("Stderr { .. }")
586 #[stable(feature = "rust1", since = "1.0.0")]
587 impl Write for Stderr {
588 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
589 self.lock().write(buf)
591 fn flush(&mut self) -> io::Result<()> {
594 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
595 self.lock().write_all(buf)
597 fn write_fmt(&mut self, args: fmt::Arguments) -> io::Result<()> {
598 self.lock().write_fmt(args)
601 #[stable(feature = "rust1", since = "1.0.0")]
602 impl<'a> Write for StderrLock<'a> {
603 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
604 self.inner.borrow_mut().write(buf)
606 fn flush(&mut self) -> io::Result<()> {
607 self.inner.borrow_mut().flush()
611 #[stable(feature = "std_debug", since = "1.16.0")]
612 impl<'a> fmt::Debug for StderrLock<'a> {
613 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
614 f.pad("StderrLock { .. }")
618 /// Resets the thread-local stderr handle to the specified writer
620 /// This will replace the current thread's stderr handle, returning the old
621 /// handle. All future calls to `panic!` and friends will emit their output to
622 /// this specified handle.
624 /// Note that this does not need to be called for all new threads; the default
625 /// output handle is to the process's stderr stream.
626 #[unstable(feature = "set_stdio",
627 reason = "this function may disappear completely or be replaced \
628 with a more general mechanism",
631 pub fn set_panic(sink: Option<Box<dyn Write + Send>>) -> Option<Box<dyn Write + Send>> {
632 use panicking::LOCAL_STDERR;
634 LOCAL_STDERR.with(move |slot| {
635 mem::replace(&mut *slot.borrow_mut(), sink)
636 }).and_then(|mut s| {
642 /// Resets the thread-local stdout handle to the specified writer
644 /// This will replace the current thread's stdout handle, returning the old
645 /// handle. All future calls to `print!` and friends will emit their output to
646 /// this specified handle.
648 /// Note that this does not need to be called for all new threads; the default
649 /// output handle is to the process's stdout stream.
650 #[unstable(feature = "set_stdio",
651 reason = "this function may disappear completely or be replaced \
652 with a more general mechanism",
655 pub fn set_print(sink: Option<Box<dyn Write + Send>>) -> Option<Box<dyn Write + Send>> {
657 LOCAL_STDOUT.with(move |slot| {
658 mem::replace(&mut *slot.borrow_mut(), sink)
659 }).and_then(|mut s| {
665 /// Write `args` to output stream `local_s` if possible, `global_s`
666 /// otherwise. `label` identifies the stream in a panic message.
668 /// This function is used to print error messages, so it takes extra
669 /// care to avoid causing a panic when `local_stream` is unusable.
670 /// For instance, if the TLS key for the local stream is
671 /// already destroyed, or if the local stream is locked by another
672 /// thread, it will just fall back to the global stream.
674 /// However, if the actual I/O causes an error, this function does panic.
676 args: fmt::Arguments,
677 local_s: &'static LocalKey<RefCell<Option<Box<dyn Write+Send>>>>,
684 let result = local_s.try_with(|s| {
685 if let Ok(mut borrowed) = s.try_borrow_mut() {
686 if let Some(w) = borrowed.as_mut() {
687 return w.write_fmt(args);
690 global_s().write_fmt(args)
691 }).unwrap_or_else(|_| {
692 global_s().write_fmt(args)
695 if let Err(e) = result {
696 panic!("failed printing to {}: {}", label, e);
700 #[unstable(feature = "print_internals",
701 reason = "implementation detail which may disappear or be replaced at any time",
704 pub fn _print(args: fmt::Arguments) {
705 print_to(args, &LOCAL_STDOUT, stdout, "stdout");
708 #[unstable(feature = "print_internals",
709 reason = "implementation detail which may disappear or be replaced at any time",
712 pub fn _eprint(args: fmt::Arguments) {
713 use panicking::LOCAL_STDERR;
714 print_to(args, &LOCAL_STDERR, stderr, "stderr");
719 use panic::{UnwindSafe, RefUnwindSafe};
724 fn stdout_unwind_safe() {
725 assert_unwind_safe::<Stdout>();
728 fn stdoutlock_unwind_safe() {
729 assert_unwind_safe::<StdoutLock>();
730 assert_unwind_safe::<StdoutLock<'static>>();
733 fn stderr_unwind_safe() {
734 assert_unwind_safe::<Stderr>();
737 fn stderrlock_unwind_safe() {
738 assert_unwind_safe::<StderrLock>();
739 assert_unwind_safe::<StderrLock<'static>>();
742 fn assert_unwind_safe<T: UnwindSafe + RefUnwindSafe>() {}
745 #[cfg_attr(target_os = "emscripten", ignore)]
746 fn panic_doesnt_poison() {
755 }).join().unwrap_err();