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, BufReader, LineWriter};
17 use sync::{Arc, Mutex, MutexGuard};
19 use sys_common::remutex::{ReentrantMutex, ReentrantMutexGuard};
20 use thread::LocalKeyState;
22 /// Stdout used by print! and println! macros
24 static LOCAL_STDOUT: RefCell<Option<Box<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) }
78 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
79 self.0.read_to_end(buf)
82 impl Write for StdoutRaw {
83 fn write(&mut self, buf: &[u8]) -> io::Result<usize> { self.0.write(buf) }
84 fn flush(&mut self) -> io::Result<()> { self.0.flush() }
86 impl Write for StderrRaw {
87 fn write(&mut self, buf: &[u8]) -> io::Result<usize> { self.0.write(buf) }
88 fn flush(&mut self) -> io::Result<()> { self.0.flush() }
96 impl<W: io::Write> io::Write for Maybe<W> {
97 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
99 Maybe::Real(ref mut w) => handle_ebadf(w.write(buf), buf.len()),
100 Maybe::Fake => Ok(buf.len())
104 fn flush(&mut self) -> io::Result<()> {
106 Maybe::Real(ref mut w) => handle_ebadf(w.flush(), ()),
107 Maybe::Fake => Ok(())
112 impl<R: io::Read> io::Read for Maybe<R> {
113 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
115 Maybe::Real(ref mut r) => handle_ebadf(r.read(buf), 0),
119 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
121 Maybe::Real(ref mut r) => handle_ebadf(r.read_to_end(buf), 0),
127 fn handle_ebadf<T>(r: io::Result<T>, default: T) -> io::Result<T> {
128 use sys::stdio::EBADF_ERR;
131 Err(ref e) if e.raw_os_error() == Some(EBADF_ERR) => Ok(default),
136 /// A handle to the standard input stream of a process.
138 /// Each handle is a shared reference to a global buffer of input data to this
139 /// process. A handle can be `lock`'d to gain full access to [`BufRead`] methods
140 /// (e.g. `.lines()`). Reads to this handle are otherwise locked with respect
143 /// This handle implements the `Read` trait, but beware that concurrent reads
144 /// of `Stdin` must be executed with care.
146 /// Created by the [`io::stdin`] method.
148 /// [`io::stdin`]: fn.stdin.html
149 /// [`BufRead`]: trait.BufRead.html
150 #[stable(feature = "rust1", since = "1.0.0")]
152 inner: Arc<Mutex<BufReader<Maybe<StdinRaw>>>>,
155 /// A locked reference to the `Stdin` handle.
157 /// This handle implements both the [`Read`] and [`BufRead`] traits, and
158 /// is constructed via the [`Stdin::lock`] method.
160 /// [`Read`]: trait.Read.html
161 /// [`BufRead`]: trait.BufRead.html
162 /// [`Stdin::lock`]: struct.Stdin.html#method.lock
163 #[stable(feature = "rust1", since = "1.0.0")]
164 pub struct StdinLock<'a> {
165 inner: MutexGuard<'a, BufReader<Maybe<StdinRaw>>>,
168 /// Constructs a new handle to the standard input of the current process.
170 /// Each handle returned is a reference to a shared global buffer whose access
171 /// is synchronized via a mutex. If you need more explicit control over
172 /// locking, see the [`lock() method`][lock].
174 /// [lock]: struct.Stdin.html#method.lock
178 /// Using implicit synchronization:
181 /// use std::io::{self, Read};
183 /// # fn foo() -> io::Result<String> {
184 /// let mut buffer = String::new();
185 /// io::stdin().read_to_string(&mut buffer)?;
190 /// Using explicit synchronization:
193 /// use std::io::{self, Read};
195 /// # fn foo() -> io::Result<String> {
196 /// let mut buffer = String::new();
197 /// let stdin = io::stdin();
198 /// let mut handle = stdin.lock();
200 /// handle.read_to_string(&mut buffer)?;
204 #[stable(feature = "rust1", since = "1.0.0")]
205 pub fn stdin() -> Stdin {
206 static INSTANCE: Lazy<Mutex<BufReader<Maybe<StdinRaw>>>> = Lazy::new(stdin_init);
208 inner: INSTANCE.get().expect("cannot access stdin during shutdown"),
211 fn stdin_init() -> Arc<Mutex<BufReader<Maybe<StdinRaw>>>> {
212 let stdin = match stdin_raw() {
213 Ok(stdin) => Maybe::Real(stdin),
217 Arc::new(Mutex::new(BufReader::with_capacity(stdio::STDIN_BUF_SIZE, stdin)))
222 /// Locks this handle to the standard input stream, returning a readable
225 /// The lock is released when the returned lock goes out of scope. The
226 /// returned guard also implements the [`Read`] and [`BufRead`] traits for
227 /// accessing the underlying data.
229 /// [`Read`]: trait.Read.html
230 /// [`BufRead`]: trait.BufRead.html
235 /// use std::io::{self, Read};
237 /// # fn foo() -> io::Result<String> {
238 /// let mut buffer = String::new();
239 /// let stdin = io::stdin();
240 /// let mut handle = stdin.lock();
242 /// handle.read_to_string(&mut buffer)?;
246 #[stable(feature = "rust1", since = "1.0.0")]
247 pub fn lock(&self) -> StdinLock {
248 StdinLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) }
251 /// Locks this handle and reads a line of input into the specified buffer.
253 /// For detailed semantics of this method, see the documentation on
254 /// [`BufRead::read_line`].
256 /// [`BufRead::read_line`]: trait.BufRead.html#method.read_line
263 /// let mut input = String::new();
264 /// match io::stdin().read_line(&mut input) {
266 /// println!("{} bytes read", n);
267 /// println!("{}", input);
269 /// Err(error) => println!("error: {}", error),
273 /// You can run the example one of two ways:
275 /// - Pipe some text to it, e.g. `printf foo | path/to/executable`
276 /// - Give it text interactively by running the executable directly,
277 /// in which case it will wait for the Enter key to be pressed before
279 #[stable(feature = "rust1", since = "1.0.0")]
280 pub fn read_line(&self, buf: &mut String) -> io::Result<usize> {
281 self.lock().read_line(buf)
285 #[stable(feature = "std_debug", since = "1.16.0")]
286 impl fmt::Debug for Stdin {
287 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
288 f.pad("Stdin { .. }")
292 #[stable(feature = "rust1", since = "1.0.0")]
293 impl Read for Stdin {
294 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
295 self.lock().read(buf)
297 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
298 self.lock().read_to_end(buf)
300 fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
301 self.lock().read_to_string(buf)
303 fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
304 self.lock().read_exact(buf)
308 #[stable(feature = "rust1", since = "1.0.0")]
309 impl<'a> Read for StdinLock<'a> {
310 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
313 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
314 self.inner.read_to_end(buf)
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 foo() -> io::Result<()> {
377 /// io::stdout().write(b"hello world")?;
383 /// Using explicit synchronization:
386 /// use std::io::{self, Write};
388 /// # fn foo() -> 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 = 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 let stdout = match stdout_raw() {
407 Ok(stdout) => Maybe::Real(stdout),
410 Arc::new(ReentrantMutex::new(RefCell::new(LineWriter::new(stdout))))
415 /// Locks this handle to the standard output stream, returning a writable
418 /// The lock is released when the returned lock goes out of scope. The
419 /// returned guard also implements the `Write` trait for writing data.
424 /// use std::io::{self, Write};
426 /// # fn foo() -> io::Result<()> {
427 /// let stdout = io::stdout();
428 /// let mut handle = stdout.lock();
430 /// handle.write(b"hello world")?;
435 #[stable(feature = "rust1", since = "1.0.0")]
436 pub fn lock(&self) -> StdoutLock {
437 StdoutLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) }
441 #[stable(feature = "std_debug", since = "1.16.0")]
442 impl fmt::Debug for Stdout {
443 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
444 f.pad("Stdout { .. }")
448 #[stable(feature = "rust1", since = "1.0.0")]
449 impl Write for Stdout {
450 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
451 self.lock().write(buf)
453 fn flush(&mut self) -> io::Result<()> {
456 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
457 self.lock().write_all(buf)
459 fn write_fmt(&mut self, args: fmt::Arguments) -> io::Result<()> {
460 self.lock().write_fmt(args)
463 #[stable(feature = "rust1", since = "1.0.0")]
464 impl<'a> Write for StdoutLock<'a> {
465 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
466 self.inner.borrow_mut().write(buf)
468 fn flush(&mut self) -> io::Result<()> {
469 self.inner.borrow_mut().flush()
473 #[stable(feature = "std_debug", since = "1.16.0")]
474 impl<'a> fmt::Debug for StdoutLock<'a> {
475 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
476 f.pad("StdoutLock { .. }")
480 /// A handle to the standard error stream of a process.
482 /// For more information, see the [`io::stderr`] method.
484 /// [`io::stderr`]: fn.stderr.html
485 #[stable(feature = "rust1", since = "1.0.0")]
487 inner: Arc<ReentrantMutex<RefCell<Maybe<StderrRaw>>>>,
490 /// A locked reference to the `Stderr` handle.
492 /// This handle implements the `Write` trait and is constructed via
493 /// the [`Stderr::lock`] method.
495 /// [`Stderr::lock`]: struct.Stderr.html#method.lock
496 #[stable(feature = "rust1", since = "1.0.0")]
497 pub struct StderrLock<'a> {
498 inner: ReentrantMutexGuard<'a, RefCell<Maybe<StderrRaw>>>,
501 /// Constructs a new handle to the standard error of the current process.
503 /// This handle is not buffered.
507 /// Using implicit synchronization:
510 /// use std::io::{self, Write};
512 /// # fn foo() -> io::Result<()> {
513 /// io::stderr().write(b"hello world")?;
519 /// Using explicit synchronization:
522 /// use std::io::{self, Write};
524 /// # fn foo() -> io::Result<()> {
525 /// let stderr = io::stderr();
526 /// let mut handle = stderr.lock();
528 /// handle.write(b"hello world")?;
533 #[stable(feature = "rust1", since = "1.0.0")]
534 pub fn stderr() -> Stderr {
535 static INSTANCE: Lazy<ReentrantMutex<RefCell<Maybe<StderrRaw>>>> = Lazy::new(stderr_init);
537 inner: INSTANCE.get().expect("cannot access stderr during shutdown"),
540 fn stderr_init() -> Arc<ReentrantMutex<RefCell<Maybe<StderrRaw>>>> {
541 let stderr = match stderr_raw() {
542 Ok(stderr) => Maybe::Real(stderr),
545 Arc::new(ReentrantMutex::new(RefCell::new(stderr)))
550 /// Locks this handle to the standard error stream, returning a writable
553 /// The lock is released when the returned lock goes out of scope. The
554 /// returned guard also implements the `Write` trait for writing data.
559 /// use std::io::{self, Write};
561 /// fn foo() -> io::Result<()> {
562 /// let stderr = io::stderr();
563 /// let mut handle = stderr.lock();
565 /// handle.write(b"hello world")?;
570 #[stable(feature = "rust1", since = "1.0.0")]
571 pub fn lock(&self) -> StderrLock {
572 StderrLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) }
576 #[stable(feature = "std_debug", since = "1.16.0")]
577 impl fmt::Debug for Stderr {
578 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
579 f.pad("Stderr { .. }")
583 #[stable(feature = "rust1", since = "1.0.0")]
584 impl Write for Stderr {
585 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
586 self.lock().write(buf)
588 fn flush(&mut self) -> io::Result<()> {
591 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
592 self.lock().write_all(buf)
594 fn write_fmt(&mut self, args: fmt::Arguments) -> io::Result<()> {
595 self.lock().write_fmt(args)
598 #[stable(feature = "rust1", since = "1.0.0")]
599 impl<'a> Write for StderrLock<'a> {
600 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
601 self.inner.borrow_mut().write(buf)
603 fn flush(&mut self) -> io::Result<()> {
604 self.inner.borrow_mut().flush()
608 #[stable(feature = "std_debug", since = "1.16.0")]
609 impl<'a> fmt::Debug for StderrLock<'a> {
610 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
611 f.pad("StderrLock { .. }")
615 /// Resets the thread-local stderr handle to the specified writer
617 /// This will replace the current thread's stderr handle, returning the old
618 /// handle. All future calls to `panic!` and friends will emit their output to
619 /// this specified handle.
621 /// Note that this does not need to be called for all new threads; the default
622 /// output handle is to the process's stderr stream.
623 #[unstable(feature = "set_stdio",
624 reason = "this function may disappear completely or be replaced \
625 with a more general mechanism",
628 pub fn set_panic(sink: Option<Box<Write + Send>>) -> Option<Box<Write + Send>> {
629 use panicking::LOCAL_STDERR;
631 LOCAL_STDERR.with(move |slot| {
632 mem::replace(&mut *slot.borrow_mut(), sink)
633 }).and_then(|mut s| {
639 /// Resets the thread-local stdout handle to the specified writer
641 /// This will replace the current thread's stdout handle, returning the old
642 /// handle. All future calls to `print!` and friends will emit their output to
643 /// this specified handle.
645 /// Note that this does not need to be called for all new threads; the default
646 /// output handle is to the process's stdout stream.
647 #[unstable(feature = "set_stdio",
648 reason = "this function may disappear completely or be replaced \
649 with a more general mechanism",
652 pub fn set_print(sink: Option<Box<Write + Send>>) -> Option<Box<Write + Send>> {
654 LOCAL_STDOUT.with(move |slot| {
655 mem::replace(&mut *slot.borrow_mut(), sink)
656 }).and_then(|mut s| {
662 #[unstable(feature = "print",
663 reason = "implementation detail which may disappear or be replaced at any time",
666 pub fn _print(args: fmt::Arguments) {
667 // As an implementation of the `println!` macro, we want to try our best to
668 // not panic wherever possible and get the output somewhere. There are
669 // currently two possible vectors for panics we take care of here:
671 // 1. If the TLS key for the local stdout has been destroyed, accessing it
672 // would cause a panic. Note that we just lump in the uninitialized case
673 // here for convenience, we're not trying to avoid a panic.
674 // 2. If the local stdout is currently in use (e.g. we're in the middle of
675 // already printing) then accessing again would cause a panic.
677 // If, however, the actual I/O causes an error, we do indeed panic.
678 let result = match LOCAL_STDOUT.state() {
679 LocalKeyState::Uninitialized |
680 LocalKeyState::Destroyed => stdout().write_fmt(args),
681 LocalKeyState::Valid => {
682 LOCAL_STDOUT.with(|s| {
683 if let Ok(mut borrowed) = s.try_borrow_mut() {
684 if let Some(w) = borrowed.as_mut() {
685 return w.write_fmt(args);
688 stdout().write_fmt(args)
692 if let Err(e) = result {
693 panic!("failed printing to stdout: {}", e);
703 #[cfg_attr(target_os = "emscripten", ignore)]
704 fn panic_doesnt_poison() {
713 }).join().unwrap_err();