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};
20 use thread::{LocalKey, 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) }
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> {
124 use sys::stdio::EBADF_ERR;
127 Err(ref e) if e.raw_os_error() == Some(EBADF_ERR) => Ok(default),
132 /// A handle to the standard input stream of a process.
134 /// Each handle is a shared reference to a global buffer of input data to this
135 /// process. A handle can be `lock`'d to gain full access to [`BufRead`] methods
136 /// (e.g. `.lines()`). Reads to this handle are otherwise locked with respect
139 /// This handle implements the `Read` trait, but beware that concurrent reads
140 /// of `Stdin` must be executed with care.
142 /// Created by the [`io::stdin`] method.
144 /// [`io::stdin`]: fn.stdin.html
145 /// [`BufRead`]: trait.BufRead.html
146 #[stable(feature = "rust1", since = "1.0.0")]
148 inner: Arc<Mutex<BufReader<Maybe<StdinRaw>>>>,
151 /// A locked reference to the `Stdin` handle.
153 /// This handle implements both the [`Read`] and [`BufRead`] traits, and
154 /// is constructed via the [`Stdin::lock`] method.
156 /// [`Read`]: trait.Read.html
157 /// [`BufRead`]: trait.BufRead.html
158 /// [`Stdin::lock`]: struct.Stdin.html#method.lock
159 #[stable(feature = "rust1", since = "1.0.0")]
160 pub struct StdinLock<'a> {
161 inner: MutexGuard<'a, BufReader<Maybe<StdinRaw>>>,
164 /// Constructs a new handle to the standard input of the current process.
166 /// Each handle returned is a reference to a shared global buffer whose access
167 /// is synchronized via a mutex. If you need more explicit control over
168 /// locking, see the [`lock() method`][lock].
170 /// [lock]: struct.Stdin.html#method.lock
174 /// Using implicit synchronization:
177 /// use std::io::{self, Read};
179 /// # fn foo() -> io::Result<String> {
180 /// let mut buffer = String::new();
181 /// io::stdin().read_to_string(&mut buffer)?;
186 /// Using explicit synchronization:
189 /// use std::io::{self, Read};
191 /// # fn foo() -> io::Result<String> {
192 /// let mut buffer = String::new();
193 /// let stdin = io::stdin();
194 /// let mut handle = stdin.lock();
196 /// handle.read_to_string(&mut buffer)?;
200 #[stable(feature = "rust1", since = "1.0.0")]
201 pub fn stdin() -> Stdin {
202 static INSTANCE: Lazy<Mutex<BufReader<Maybe<StdinRaw>>>> = Lazy::new(stdin_init);
204 inner: INSTANCE.get().expect("cannot access stdin during shutdown"),
207 fn stdin_init() -> Arc<Mutex<BufReader<Maybe<StdinRaw>>>> {
208 let stdin = match stdin_raw() {
209 Ok(stdin) => Maybe::Real(stdin),
213 Arc::new(Mutex::new(BufReader::with_capacity(stdio::STDIN_BUF_SIZE, stdin)))
218 /// Locks this handle to the standard input stream, returning a readable
221 /// The lock is released when the returned lock goes out of scope. The
222 /// returned guard also implements the [`Read`] and [`BufRead`] traits for
223 /// accessing the underlying data.
225 /// [`Read`]: trait.Read.html
226 /// [`BufRead`]: trait.BufRead.html
231 /// use std::io::{self, Read};
233 /// # fn foo() -> io::Result<String> {
234 /// let mut buffer = String::new();
235 /// let stdin = io::stdin();
236 /// let mut handle = stdin.lock();
238 /// handle.read_to_string(&mut buffer)?;
242 #[stable(feature = "rust1", since = "1.0.0")]
243 pub fn lock(&self) -> StdinLock {
244 StdinLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) }
247 /// Locks this handle and reads a line of input into the specified buffer.
249 /// For detailed semantics of this method, see the documentation on
250 /// [`BufRead::read_line`].
252 /// [`BufRead::read_line`]: trait.BufRead.html#method.read_line
259 /// let mut input = String::new();
260 /// match io::stdin().read_line(&mut input) {
262 /// println!("{} bytes read", n);
263 /// println!("{}", input);
265 /// Err(error) => println!("error: {}", error),
269 /// You can run the example one of two ways:
271 /// - Pipe some text to it, e.g. `printf foo | path/to/executable`
272 /// - Give it text interactively by running the executable directly,
273 /// in which case it will wait for the Enter key to be pressed before
275 #[stable(feature = "rust1", since = "1.0.0")]
276 pub fn read_line(&self, buf: &mut String) -> io::Result<usize> {
277 self.lock().read_line(buf)
281 #[stable(feature = "std_debug", since = "1.16.0")]
282 impl fmt::Debug for Stdin {
283 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
284 f.pad("Stdin { .. }")
288 #[stable(feature = "rust1", since = "1.0.0")]
289 impl Read for Stdin {
290 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
291 self.lock().read(buf)
294 unsafe fn initializer(&self) -> Initializer {
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> {
314 unsafe fn initializer(&self) -> Initializer {
319 #[stable(feature = "rust1", since = "1.0.0")]
320 impl<'a> BufRead for StdinLock<'a> {
321 fn fill_buf(&mut self) -> io::Result<&[u8]> { self.inner.fill_buf() }
322 fn consume(&mut self, n: usize) { self.inner.consume(n) }
325 #[stable(feature = "std_debug", since = "1.16.0")]
326 impl<'a> fmt::Debug for StdinLock<'a> {
327 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
328 f.pad("StdinLock { .. }")
332 /// A handle to the global standard output stream of the current process.
334 /// Each handle shares a global buffer of data to be written to the standard
335 /// output stream. Access is also synchronized via a lock and explicit control
336 /// over locking is available via the [`lock`] method.
338 /// Created by the [`io::stdout`] method.
340 /// [`lock`]: #method.lock
341 /// [`io::stdout`]: fn.stdout.html
342 #[stable(feature = "rust1", since = "1.0.0")]
344 // FIXME: this should be LineWriter or BufWriter depending on the state of
345 // stdout (tty or not). Note that if this is not line buffered it
346 // should also flush-on-panic or some form of flush-on-abort.
347 inner: Arc<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>>,
350 /// A locked reference to the `Stdout` handle.
352 /// This handle implements the [`Write`] trait, and is constructed via
353 /// the [`Stdout::lock`] method.
355 /// [`Write`]: trait.Write.html
356 /// [`Stdout::lock`]: struct.Stdout.html#method.lock
357 #[stable(feature = "rust1", since = "1.0.0")]
358 pub struct StdoutLock<'a> {
359 inner: ReentrantMutexGuard<'a, RefCell<LineWriter<Maybe<StdoutRaw>>>>,
362 /// Constructs a new handle to the standard output of the current process.
364 /// Each handle returned is a reference to a shared global buffer whose access
365 /// is synchronized via a mutex. If you need more explicit control over
366 /// locking, see the [Stdout::lock] method.
368 /// [Stdout::lock]: struct.Stdout.html#method.lock
372 /// Using implicit synchronization:
375 /// use std::io::{self, Write};
377 /// # fn foo() -> io::Result<()> {
378 /// io::stdout().write(b"hello world")?;
384 /// Using explicit synchronization:
387 /// use std::io::{self, Write};
389 /// # fn foo() -> io::Result<()> {
390 /// let stdout = io::stdout();
391 /// let mut handle = stdout.lock();
393 /// handle.write(b"hello world")?;
398 #[stable(feature = "rust1", since = "1.0.0")]
399 pub fn stdout() -> Stdout {
400 static INSTANCE: Lazy<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>>
401 = Lazy::new(stdout_init);
403 inner: INSTANCE.get().expect("cannot access stdout during shutdown"),
406 fn stdout_init() -> Arc<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>> {
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 foo() -> 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 foo() -> io::Result<()> {
514 /// io::stderr().write(b"hello world")?;
520 /// Using explicit synchronization:
523 /// use std::io::{self, Write};
525 /// # fn foo() -> 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>>>> = Lazy::new(stderr_init);
538 inner: INSTANCE.get().expect("cannot access stderr during shutdown"),
541 fn stderr_init() -> Arc<ReentrantMutex<RefCell<Maybe<StderrRaw>>>> {
542 let stderr = match stderr_raw() {
543 Ok(stderr) => Maybe::Real(stderr),
546 Arc::new(ReentrantMutex::new(RefCell::new(stderr)))
551 /// Locks this handle to the standard error stream, returning a writable
554 /// The lock is released when the returned lock goes out of scope. The
555 /// returned guard also implements the `Write` trait for writing data.
560 /// use std::io::{self, Write};
562 /// fn foo() -> io::Result<()> {
563 /// let stderr = io::stderr();
564 /// let mut handle = stderr.lock();
566 /// handle.write(b"hello world")?;
571 #[stable(feature = "rust1", since = "1.0.0")]
572 pub fn lock(&self) -> StderrLock {
573 StderrLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) }
577 #[stable(feature = "std_debug", since = "1.16.0")]
578 impl fmt::Debug for Stderr {
579 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
580 f.pad("Stderr { .. }")
584 #[stable(feature = "rust1", since = "1.0.0")]
585 impl Write for Stderr {
586 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
587 self.lock().write(buf)
589 fn flush(&mut self) -> io::Result<()> {
592 fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
593 self.lock().write_all(buf)
595 fn write_fmt(&mut self, args: fmt::Arguments) -> io::Result<()> {
596 self.lock().write_fmt(args)
599 #[stable(feature = "rust1", since = "1.0.0")]
600 impl<'a> Write for StderrLock<'a> {
601 fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
602 self.inner.borrow_mut().write(buf)
604 fn flush(&mut self) -> io::Result<()> {
605 self.inner.borrow_mut().flush()
609 #[stable(feature = "std_debug", since = "1.16.0")]
610 impl<'a> fmt::Debug for StderrLock<'a> {
611 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
612 f.pad("StderrLock { .. }")
616 /// Resets the thread-local stderr handle to the specified writer
618 /// This will replace the current thread's stderr handle, returning the old
619 /// handle. All future calls to `panic!` and friends will emit their output to
620 /// this specified handle.
622 /// Note that this does not need to be called for all new threads; the default
623 /// output handle is to the process's stderr stream.
624 #[unstable(feature = "set_stdio",
625 reason = "this function may disappear completely or be replaced \
626 with a more general mechanism",
629 pub fn set_panic(sink: Option<Box<Write + Send>>) -> Option<Box<Write + Send>> {
630 use panicking::LOCAL_STDERR;
632 LOCAL_STDERR.with(move |slot| {
633 mem::replace(&mut *slot.borrow_mut(), sink)
634 }).and_then(|mut s| {
640 /// Resets the thread-local stdout handle to the specified writer
642 /// This will replace the current thread's stdout handle, returning the old
643 /// handle. All future calls to `print!` and friends will emit their output to
644 /// this specified handle.
646 /// Note that this does not need to be called for all new threads; the default
647 /// output handle is to the process's stdout stream.
648 #[unstable(feature = "set_stdio",
649 reason = "this function may disappear completely or be replaced \
650 with a more general mechanism",
653 pub fn set_print(sink: Option<Box<Write + Send>>) -> Option<Box<Write + Send>> {
655 LOCAL_STDOUT.with(move |slot| {
656 mem::replace(&mut *slot.borrow_mut(), sink)
657 }).and_then(|mut s| {
663 /// Write `args` to output stream `local_s` if possible, `global_s`
664 /// otherwise. `label` identifies the stream in a panic message.
666 /// This function is used to print error messages, so it takes extra
667 /// care to avoid causing a panic when `local_stream` is unusable.
668 /// For instance, if the TLS key for the local stream is uninitialized
669 /// or already destroyed, or if the local stream is locked by another
670 /// thread, it will just fall back to the global stream.
672 /// However, if the actual I/O causes an error, this function does panic.
673 fn print_to<T>(args: fmt::Arguments,
674 local_s: &'static LocalKey<RefCell<Option<Box<Write+Send>>>>,
676 label: &str) where T: Write {
677 let result = match local_s.state() {
678 LocalKeyState::Uninitialized |
679 LocalKeyState::Destroyed => global_s().write_fmt(args),
680 LocalKeyState::Valid => {
682 if let Ok(mut borrowed) = s.try_borrow_mut() {
683 if let Some(w) = borrowed.as_mut() {
684 return w.write_fmt(args);
687 global_s().write_fmt(args)
691 if let Err(e) = result {
692 panic!("failed printing to {}: {}", label, e);
696 #[unstable(feature = "print_internals",
697 reason = "implementation detail which may disappear or be replaced at any time",
700 pub fn _print(args: fmt::Arguments) {
701 print_to(args, &LOCAL_STDOUT, stdout, "stdout");
704 #[unstable(feature = "print_internals",
705 reason = "implementation detail which may disappear or be replaced at any time",
708 pub fn _eprint(args: fmt::Arguments) {
709 use panicking::LOCAL_STDERR;
710 print_to(args, &LOCAL_STDERR, stderr, "stderr");
719 #[cfg_attr(target_os = "emscripten", ignore)]
720 fn panic_doesnt_poison() {
729 }).join().unwrap_err();