diff options
Diffstat (limited to 'library/std/src/io/stdio.rs')
| -rw-r--r-- | library/std/src/io/stdio.rs | 1064 |
1 files changed, 1064 insertions, 0 deletions
diff --git a/library/std/src/io/stdio.rs b/library/std/src/io/stdio.rs new file mode 100644 index 00000000000..156f555be02 --- /dev/null +++ b/library/std/src/io/stdio.rs @@ -0,0 +1,1064 @@ +#![cfg_attr(test, allow(unused))] + +use crate::io::prelude::*; + +use crate::cell::RefCell; +use crate::fmt; +use crate::io::lazy::Lazy; +use crate::io::{self, BufReader, Initializer, IoSlice, IoSliceMut, LineWriter}; +use crate::sync::{Arc, Mutex, MutexGuard, Once}; +use crate::sys::stdio; +use crate::sys_common::remutex::{ReentrantMutex, ReentrantMutexGuard}; +use crate::thread::LocalKey; + +thread_local! { + /// Stdout used by print! and println! macros + static LOCAL_STDOUT: RefCell<Option<Box<dyn Write + Send>>> = { + RefCell::new(None) + } +} + +thread_local! { + /// Stderr used by eprint! and eprintln! macros, and panics + static LOCAL_STDERR: RefCell<Option<Box<dyn Write + Send>>> = { + RefCell::new(None) + } +} + +/// A handle to a raw instance of the standard input stream of this process. +/// +/// This handle is not synchronized or buffered in any fashion. Constructed via +/// the `std::io::stdio::stdin_raw` function. +struct StdinRaw(stdio::Stdin); + +/// A handle to a raw instance of the standard output stream of this process. +/// +/// This handle is not synchronized or buffered in any fashion. Constructed via +/// the `std::io::stdio::stdout_raw` function. +struct StdoutRaw(stdio::Stdout); + +/// A handle to a raw instance of the standard output stream of this process. +/// +/// This handle is not synchronized or buffered in any fashion. Constructed via +/// the `std::io::stdio::stderr_raw` function. +struct StderrRaw(stdio::Stderr); + +/// Constructs a new raw handle to the standard input of this process. +/// +/// The returned handle does not interact with any other handles created nor +/// handles returned by `std::io::stdin`. Data buffered by the `std::io::stdin` +/// handles is **not** available to raw handles returned from this function. +/// +/// The returned handle has no external synchronization or buffering. +fn stdin_raw() -> io::Result<StdinRaw> { + stdio::Stdin::new().map(StdinRaw) +} + +/// Constructs a new raw handle to the standard output stream of this process. +/// +/// The returned handle does not interact with any other handles created nor +/// handles returned by `std::io::stdout`. Note that data is buffered by the +/// `std::io::stdout` handles so writes which happen via this raw handle may +/// appear before previous writes. +/// +/// The returned handle has no external synchronization or buffering layered on +/// top. +fn stdout_raw() -> io::Result<StdoutRaw> { + stdio::Stdout::new().map(StdoutRaw) +} + +/// Constructs a new raw handle to the standard error stream of this process. +/// +/// The returned handle does not interact with any other handles created nor +/// handles returned by `std::io::stderr`. +/// +/// The returned handle has no external synchronization or buffering layered on +/// top. +fn stderr_raw() -> io::Result<StderrRaw> { + stdio::Stderr::new().map(StderrRaw) +} + +impl Read for StdinRaw { + fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { + self.0.read(buf) + } + + fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> { + self.0.read_vectored(bufs) + } + + #[inline] + fn is_read_vectored(&self) -> bool { + self.0.is_read_vectored() + } + + #[inline] + unsafe fn initializer(&self) -> Initializer { + Initializer::nop() + } + + fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> { + self.0.read_to_end(buf) + } + + fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> { + self.0.read_to_string(buf) + } + + fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> { + self.0.read_exact(buf) + } +} + +impl Write for StdoutRaw { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + self.0.write(buf) + } + + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + self.0.write_vectored(bufs) + } + + #[inline] + fn is_write_vectored(&self) -> bool { + self.0.is_write_vectored() + } + + fn flush(&mut self) -> io::Result<()> { + self.0.flush() + } + + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + self.0.write_all(buf) + } + + fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> { + self.0.write_all_vectored(bufs) + } + + fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> { + self.0.write_fmt(fmt) + } +} + +impl Write for StderrRaw { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + self.0.write(buf) + } + + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + self.0.write_vectored(bufs) + } + + #[inline] + fn is_write_vectored(&self) -> bool { + self.0.is_write_vectored() + } + + fn flush(&mut self) -> io::Result<()> { + self.0.flush() + } + + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + self.0.write_all(buf) + } + + fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> { + self.0.write_all_vectored(bufs) + } + + fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> { + self.0.write_fmt(fmt) + } +} + +enum Maybe<T> { + Real(T), + Fake, +} + +impl<W: io::Write> io::Write for Maybe<W> { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + match *self { + Maybe::Real(ref mut w) => handle_ebadf(w.write(buf), buf.len()), + Maybe::Fake => Ok(buf.len()), + } + } + + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + let total = bufs.iter().map(|b| b.len()).sum(); + match self { + Maybe::Real(w) => handle_ebadf(w.write_vectored(bufs), total), + Maybe::Fake => Ok(total), + } + } + + #[inline] + fn is_write_vectored(&self) -> bool { + match self { + Maybe::Real(w) => w.is_write_vectored(), + Maybe::Fake => true, + } + } + + fn flush(&mut self) -> io::Result<()> { + match *self { + Maybe::Real(ref mut w) => handle_ebadf(w.flush(), ()), + Maybe::Fake => Ok(()), + } + } +} + +impl<R: io::Read> io::Read for Maybe<R> { + fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { + match *self { + Maybe::Real(ref mut r) => handle_ebadf(r.read(buf), 0), + Maybe::Fake => Ok(0), + } + } + + fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> { + match self { + Maybe::Real(r) => handle_ebadf(r.read_vectored(bufs), 0), + Maybe::Fake => Ok(0), + } + } + + #[inline] + fn is_read_vectored(&self) -> bool { + match self { + Maybe::Real(w) => w.is_read_vectored(), + Maybe::Fake => true, + } + } +} + +fn handle_ebadf<T>(r: io::Result<T>, default: T) -> io::Result<T> { + match r { + Err(ref e) if stdio::is_ebadf(e) => Ok(default), + r => r, + } +} + +/// A handle to the standard input stream of a process. +/// +/// Each handle is a shared reference to a global buffer of input data to this +/// process. A handle can be `lock`'d to gain full access to [`BufRead`] methods +/// (e.g., `.lines()`). Reads to this handle are otherwise locked with respect +/// to other reads. +/// +/// This handle implements the `Read` trait, but beware that concurrent reads +/// of `Stdin` must be executed with care. +/// +/// Created by the [`io::stdin`] method. +/// +/// [`io::stdin`]: fn.stdin.html +/// [`BufRead`]: trait.BufRead.html +/// +/// ### Note: Windows Portability Consideration +/// +/// When operating in a console, the Windows implementation of this stream does not support +/// non-UTF-8 byte sequences. Attempting to read bytes that are not valid UTF-8 will return +/// an error. +/// +/// # Examples +/// +/// ```no_run +/// use std::io::{self, Read}; +/// +/// fn main() -> io::Result<()> { +/// let mut buffer = String::new(); +/// let mut stdin = io::stdin(); // We get `Stdin` here. +/// stdin.read_to_string(&mut buffer)?; +/// Ok(()) +/// } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Stdin { + inner: Arc<Mutex<BufReader<Maybe<StdinRaw>>>>, +} + +/// A locked reference to the `Stdin` handle. +/// +/// This handle implements both the [`Read`] and [`BufRead`] traits, and +/// is constructed via the [`Stdin::lock`] method. +/// +/// [`Read`]: trait.Read.html +/// [`BufRead`]: trait.BufRead.html +/// [`Stdin::lock`]: struct.Stdin.html#method.lock +/// +/// ### Note: Windows Portability Consideration +/// +/// When operating in a console, the Windows implementation of this stream does not support +/// non-UTF-8 byte sequences. Attempting to read bytes that are not valid UTF-8 will return +/// an error. +/// +/// # Examples +/// +/// ```no_run +/// use std::io::{self, Read}; +/// +/// fn main() -> io::Result<()> { +/// let mut buffer = String::new(); +/// let stdin = io::stdin(); // We get `Stdin` here. +/// { +/// let mut stdin_lock = stdin.lock(); // We get `StdinLock` here. +/// stdin_lock.read_to_string(&mut buffer)?; +/// } // `StdinLock` is dropped here. +/// Ok(()) +/// } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub struct StdinLock<'a> { + inner: MutexGuard<'a, BufReader<Maybe<StdinRaw>>>, +} + +/// Constructs a new handle to the standard input of the current process. +/// +/// Each handle returned is a reference to a shared global buffer whose access +/// is synchronized via a mutex. If you need more explicit control over +/// locking, see the [`Stdin::lock`] method. +/// +/// [`Stdin::lock`]: struct.Stdin.html#method.lock +/// +/// ### Note: Windows Portability Consideration +/// When operating in a console, the Windows implementation of this stream does not support +/// non-UTF-8 byte sequences. Attempting to read bytes that are not valid UTF-8 will return +/// an error. +/// +/// # Examples +/// +/// Using implicit synchronization: +/// +/// ```no_run +/// use std::io::{self, Read}; +/// +/// fn main() -> io::Result<()> { +/// let mut buffer = String::new(); +/// io::stdin().read_to_string(&mut buffer)?; +/// Ok(()) +/// } +/// ``` +/// +/// Using explicit synchronization: +/// +/// ```no_run +/// use std::io::{self, Read}; +/// +/// fn main() -> io::Result<()> { +/// let mut buffer = String::new(); +/// let stdin = io::stdin(); +/// let mut handle = stdin.lock(); +/// +/// handle.read_to_string(&mut buffer)?; +/// Ok(()) +/// } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub fn stdin() -> Stdin { + static INSTANCE: Lazy<Mutex<BufReader<Maybe<StdinRaw>>>> = Lazy::new(); + return Stdin { + inner: unsafe { INSTANCE.get(stdin_init).expect("cannot access stdin during shutdown") }, + }; + + fn stdin_init() -> Arc<Mutex<BufReader<Maybe<StdinRaw>>>> { + // This must not reentrantly access `INSTANCE` + let stdin = match stdin_raw() { + Ok(stdin) => Maybe::Real(stdin), + _ => Maybe::Fake, + }; + + Arc::new(Mutex::new(BufReader::with_capacity(stdio::STDIN_BUF_SIZE, stdin))) + } +} + +impl Stdin { + /// Locks this handle to the standard input stream, returning a readable + /// guard. + /// + /// The lock is released when the returned lock goes out of scope. The + /// returned guard also implements the [`Read`] and [`BufRead`] traits for + /// accessing the underlying data. + /// + /// [`Read`]: trait.Read.html + /// [`BufRead`]: trait.BufRead.html + /// + /// # Examples + /// + /// ```no_run + /// use std::io::{self, Read}; + /// + /// fn main() -> io::Result<()> { + /// let mut buffer = String::new(); + /// let stdin = io::stdin(); + /// let mut handle = stdin.lock(); + /// + /// handle.read_to_string(&mut buffer)?; + /// Ok(()) + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn lock(&self) -> StdinLock<'_> { + StdinLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) } + } + + /// Locks this handle and reads a line of input, appending it to the specified buffer. + /// + /// For detailed semantics of this method, see the documentation on + /// [`BufRead::read_line`]. + /// + /// [`BufRead::read_line`]: trait.BufRead.html#method.read_line + /// + /// # Examples + /// + /// ```no_run + /// use std::io; + /// + /// let mut input = String::new(); + /// match io::stdin().read_line(&mut input) { + /// Ok(n) => { + /// println!("{} bytes read", n); + /// println!("{}", input); + /// } + /// Err(error) => println!("error: {}", error), + /// } + /// ``` + /// + /// You can run the example one of two ways: + /// + /// - Pipe some text to it, e.g., `printf foo | path/to/executable` + /// - Give it text interactively by running the executable directly, + /// in which case it will wait for the Enter key to be pressed before + /// continuing + #[stable(feature = "rust1", since = "1.0.0")] + pub fn read_line(&self, buf: &mut String) -> io::Result<usize> { + self.lock().read_line(buf) + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for Stdin { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.pad("Stdin { .. }") + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Read for Stdin { + fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { + self.lock().read(buf) + } + fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> { + self.lock().read_vectored(bufs) + } + #[inline] + fn is_read_vectored(&self) -> bool { + self.lock().is_read_vectored() + } + #[inline] + unsafe fn initializer(&self) -> Initializer { + Initializer::nop() + } + fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> { + self.lock().read_to_end(buf) + } + fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> { + self.lock().read_to_string(buf) + } + fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> { + self.lock().read_exact(buf) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Read for StdinLock<'_> { + fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { + self.inner.read(buf) + } + + fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> { + self.inner.read_vectored(bufs) + } + + #[inline] + fn is_read_vectored(&self) -> bool { + self.inner.is_read_vectored() + } + + #[inline] + unsafe fn initializer(&self) -> Initializer { + Initializer::nop() + } + + fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> { + self.inner.read_to_end(buf) + } + + fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> { + self.inner.read_to_string(buf) + } + + fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> { + self.inner.read_exact(buf) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl BufRead for StdinLock<'_> { + fn fill_buf(&mut self) -> io::Result<&[u8]> { + self.inner.fill_buf() + } + + fn consume(&mut self, n: usize) { + self.inner.consume(n) + } + + fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> { + self.inner.read_until(byte, buf) + } + + fn read_line(&mut self, buf: &mut String) -> io::Result<usize> { + self.inner.read_line(buf) + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for StdinLock<'_> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.pad("StdinLock { .. }") + } +} + +/// A handle to the global standard output stream of the current process. +/// +/// Each handle shares a global buffer of data to be written to the standard +/// output stream. Access is also synchronized via a lock and explicit control +/// over locking is available via the [`lock`] method. +/// +/// Created by the [`io::stdout`] method. +/// +/// ### Note: Windows Portability Consideration +/// When operating in a console, the Windows implementation of this stream does not support +/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return +/// an error. +/// +/// [`lock`]: #method.lock +/// [`io::stdout`]: fn.stdout.html +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Stdout { + // FIXME: this should be LineWriter or BufWriter depending on the state of + // stdout (tty or not). Note that if this is not line buffered it + // should also flush-on-panic or some form of flush-on-abort. + inner: Arc<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>>, +} + +/// A locked reference to the `Stdout` handle. +/// +/// This handle implements the [`Write`] trait, and is constructed via +/// the [`Stdout::lock`] method. +/// +/// ### Note: Windows Portability Consideration +/// When operating in a console, the Windows implementation of this stream does not support +/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return +/// an error. +/// +/// [`Write`]: trait.Write.html +/// [`Stdout::lock`]: struct.Stdout.html#method.lock +#[stable(feature = "rust1", since = "1.0.0")] +pub struct StdoutLock<'a> { + inner: ReentrantMutexGuard<'a, RefCell<LineWriter<Maybe<StdoutRaw>>>>, +} + +/// Constructs a new handle to the standard output of the current process. +/// +/// Each handle returned is a reference to a shared global buffer whose access +/// is synchronized via a mutex. If you need more explicit control over +/// locking, see the [`Stdout::lock`] method. +/// +/// [`Stdout::lock`]: struct.Stdout.html#method.lock +/// +/// ### Note: Windows Portability Consideration +/// When operating in a console, the Windows implementation of this stream does not support +/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return +/// an error. +/// +/// # Examples +/// +/// Using implicit synchronization: +/// +/// ```no_run +/// use std::io::{self, Write}; +/// +/// fn main() -> io::Result<()> { +/// io::stdout().write_all(b"hello world")?; +/// +/// Ok(()) +/// } +/// ``` +/// +/// Using explicit synchronization: +/// +/// ```no_run +/// use std::io::{self, Write}; +/// +/// fn main() -> io::Result<()> { +/// let stdout = io::stdout(); +/// let mut handle = stdout.lock(); +/// +/// handle.write_all(b"hello world")?; +/// +/// Ok(()) +/// } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub fn stdout() -> Stdout { + static INSTANCE: Lazy<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>> = Lazy::new(); + return Stdout { + inner: unsafe { INSTANCE.get(stdout_init).expect("cannot access stdout during shutdown") }, + }; + + fn stdout_init() -> Arc<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>> { + // This must not reentrantly access `INSTANCE` + let stdout = match stdout_raw() { + Ok(stdout) => Maybe::Real(stdout), + _ => Maybe::Fake, + }; + unsafe { + let ret = Arc::new(ReentrantMutex::new(RefCell::new(LineWriter::new(stdout)))); + ret.init(); + ret + } + } +} + +impl Stdout { + /// Locks this handle to the standard output stream, returning a writable + /// guard. + /// + /// The lock is released when the returned lock goes out of scope. The + /// returned guard also implements the `Write` trait for writing data. + /// + /// # Examples + /// + /// ```no_run + /// use std::io::{self, Write}; + /// + /// fn main() -> io::Result<()> { + /// let stdout = io::stdout(); + /// let mut handle = stdout.lock(); + /// + /// handle.write_all(b"hello world")?; + /// + /// Ok(()) + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn lock(&self) -> StdoutLock<'_> { + StdoutLock { inner: self.inner.lock() } + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for Stdout { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.pad("Stdout { .. }") + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Write for Stdout { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + self.lock().write(buf) + } + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + self.lock().write_vectored(bufs) + } + #[inline] + fn is_write_vectored(&self) -> bool { + self.lock().is_write_vectored() + } + fn flush(&mut self) -> io::Result<()> { + self.lock().flush() + } + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + self.lock().write_all(buf) + } + fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> { + self.lock().write_all_vectored(bufs) + } + fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> { + self.lock().write_fmt(args) + } +} +#[stable(feature = "rust1", since = "1.0.0")] +impl Write for StdoutLock<'_> { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + self.inner.borrow_mut().write(buf) + } + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + self.inner.borrow_mut().write_vectored(bufs) + } + #[inline] + fn is_write_vectored(&self) -> bool { + self.inner.borrow_mut().is_write_vectored() + } + fn flush(&mut self) -> io::Result<()> { + self.inner.borrow_mut().flush() + } + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + self.inner.borrow_mut().write_all(buf) + } + fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> { + self.inner.borrow_mut().write_all_vectored(bufs) + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for StdoutLock<'_> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.pad("StdoutLock { .. }") + } +} + +/// A handle to the standard error stream of a process. +/// +/// For more information, see the [`io::stderr`] method. +/// +/// [`io::stderr`]: fn.stderr.html +/// +/// ### Note: Windows Portability Consideration +/// When operating in a console, the Windows implementation of this stream does not support +/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return +/// an error. +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Stderr { + inner: &'static ReentrantMutex<RefCell<Maybe<StderrRaw>>>, +} + +/// A locked reference to the `Stderr` handle. +/// +/// This handle implements the `Write` trait and is constructed via +/// the [`Stderr::lock`] method. +/// +/// [`Stderr::lock`]: struct.Stderr.html#method.lock +/// +/// ### Note: Windows Portability Consideration +/// When operating in a console, the Windows implementation of this stream does not support +/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return +/// an error. +#[stable(feature = "rust1", since = "1.0.0")] +pub struct StderrLock<'a> { + inner: ReentrantMutexGuard<'a, RefCell<Maybe<StderrRaw>>>, +} + +/// Constructs a new handle to the standard error of the current process. +/// +/// This handle is not buffered. +/// +/// ### Note: Windows Portability Consideration +/// When operating in a console, the Windows implementation of this stream does not support +/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return +/// an error. +/// +/// # Examples +/// +/// Using implicit synchronization: +/// +/// ```no_run +/// use std::io::{self, Write}; +/// +/// fn main() -> io::Result<()> { +/// io::stderr().write_all(b"hello world")?; +/// +/// Ok(()) +/// } +/// ``` +/// +/// Using explicit synchronization: +/// +/// ```no_run +/// use std::io::{self, Write}; +/// +/// fn main() -> io::Result<()> { +/// let stderr = io::stderr(); +/// let mut handle = stderr.lock(); +/// +/// handle.write_all(b"hello world")?; +/// +/// Ok(()) +/// } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub fn stderr() -> Stderr { + // Note that unlike `stdout()` we don't use `Lazy` here which registers a + // destructor. Stderr is not buffered nor does the `stderr_raw` type consume + // any owned resources, so there's no need to run any destructors at some + // point in the future. + // + // This has the added benefit of allowing `stderr` to be usable during + // process shutdown as well! + static INSTANCE: ReentrantMutex<RefCell<Maybe<StderrRaw>>> = + unsafe { ReentrantMutex::new(RefCell::new(Maybe::Fake)) }; + + // When accessing stderr we need one-time initialization of the reentrant + // mutex, followed by one-time detection of whether we actually have a + // stderr handle or not. Afterwards we can just always use the now-filled-in + // `INSTANCE` value. + static INIT: Once = Once::new(); + INIT.call_once(|| unsafe { + INSTANCE.init(); + if let Ok(stderr) = stderr_raw() { + *INSTANCE.lock().borrow_mut() = Maybe::Real(stderr); + } + }); + Stderr { inner: &INSTANCE } +} + +impl Stderr { + /// Locks this handle to the standard error stream, returning a writable + /// guard. + /// + /// The lock is released when the returned lock goes out of scope. The + /// returned guard also implements the `Write` trait for writing data. + /// + /// # Examples + /// + /// ``` + /// use std::io::{self, Write}; + /// + /// fn foo() -> io::Result<()> { + /// let stderr = io::stderr(); + /// let mut handle = stderr.lock(); + /// + /// handle.write_all(b"hello world")?; + /// + /// Ok(()) + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn lock(&self) -> StderrLock<'_> { + StderrLock { inner: self.inner.lock() } + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for Stderr { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.pad("Stderr { .. }") + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Write for Stderr { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + self.lock().write(buf) + } + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + self.lock().write_vectored(bufs) + } + #[inline] + fn is_write_vectored(&self) -> bool { + self.lock().is_write_vectored() + } + fn flush(&mut self) -> io::Result<()> { + self.lock().flush() + } + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + self.lock().write_all(buf) + } + fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> { + self.lock().write_all_vectored(bufs) + } + fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> { + self.lock().write_fmt(args) + } +} +#[stable(feature = "rust1", since = "1.0.0")] +impl Write for StderrLock<'_> { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + self.inner.borrow_mut().write(buf) + } + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + self.inner.borrow_mut().write_vectored(bufs) + } + #[inline] + fn is_write_vectored(&self) -> bool { + self.inner.borrow_mut().is_write_vectored() + } + fn flush(&mut self) -> io::Result<()> { + self.inner.borrow_mut().flush() + } + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + self.inner.borrow_mut().write_all(buf) + } + fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> { + self.inner.borrow_mut().write_all_vectored(bufs) + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for StderrLock<'_> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.pad("StderrLock { .. }") + } +} + +/// Resets the thread-local stderr handle to the specified writer +/// +/// This will replace the current thread's stderr handle, returning the old +/// handle. All future calls to `panic!` and friends will emit their output to +/// this specified handle. +/// +/// Note that this does not need to be called for all new threads; the default +/// output handle is to the process's stderr stream. +#[unstable( + feature = "set_stdio", + reason = "this function may disappear completely or be replaced \ + with a more general mechanism", + issue = "none" +)] +#[doc(hidden)] +pub fn set_panic(sink: Option<Box<dyn Write + Send>>) -> Option<Box<dyn Write + Send>> { + use crate::mem; + LOCAL_STDERR.with(move |slot| mem::replace(&mut *slot.borrow_mut(), sink)).and_then(|mut s| { + let _ = s.flush(); + Some(s) + }) +} + +/// Resets the thread-local stdout handle to the specified writer +/// +/// This will replace the current thread's stdout handle, returning the old +/// handle. All future calls to `print!` and friends will emit their output to +/// this specified handle. +/// +/// Note that this does not need to be called for all new threads; the default +/// output handle is to the process's stdout stream. +#[unstable( + feature = "set_stdio", + reason = "this function may disappear completely or be replaced \ + with a more general mechanism", + issue = "none" +)] +#[doc(hidden)] +pub fn set_print(sink: Option<Box<dyn Write + Send>>) -> Option<Box<dyn Write + Send>> { + use crate::mem; + LOCAL_STDOUT.with(move |slot| mem::replace(&mut *slot.borrow_mut(), sink)).and_then(|mut s| { + let _ = s.flush(); + Some(s) + }) +} + +/// Write `args` to output stream `local_s` if possible, `global_s` +/// otherwise. `label` identifies the stream in a panic message. +/// +/// This function is used to print error messages, so it takes extra +/// care to avoid causing a panic when `local_s` is unusable. +/// For instance, if the TLS key for the local stream is +/// already destroyed, or if the local stream is locked by another +/// thread, it will just fall back to the global stream. +/// +/// However, if the actual I/O causes an error, this function does panic. +fn print_to<T>( + args: fmt::Arguments<'_>, + local_s: &'static LocalKey<RefCell<Option<Box<dyn Write + Send>>>>, + global_s: fn() -> T, + label: &str, +) where + T: Write, +{ + let result = local_s + .try_with(|s| { + // Note that we completely remove a local sink to write to in case + // our printing recursively panics/prints, so the recursive + // panic/print goes to the global sink instead of our local sink. + let prev = s.borrow_mut().take(); + if let Some(mut w) = prev { + let result = w.write_fmt(args); + *s.borrow_mut() = Some(w); + return result; + } + global_s().write_fmt(args) + }) + .unwrap_or_else(|_| global_s().write_fmt(args)); + + if let Err(e) = result { + panic!("failed printing to {}: {}", label, e); + } +} + +#[unstable( + feature = "print_internals", + reason = "implementation detail which may disappear or be replaced at any time", + issue = "none" +)] +#[doc(hidden)] +#[cfg(not(test))] +pub fn _print(args: fmt::Arguments<'_>) { + print_to(args, &LOCAL_STDOUT, stdout, "stdout"); +} + +#[unstable( + feature = "print_internals", + reason = "implementation detail which may disappear or be replaced at any time", + issue = "none" +)] +#[doc(hidden)] +#[cfg(not(test))] +pub fn _eprint(args: fmt::Arguments<'_>) { + print_to(args, &LOCAL_STDERR, stderr, "stderr"); +} + +#[cfg(test)] +pub use realstd::io::{_eprint, _print}; + +#[cfg(test)] +mod tests { + use super::*; + use crate::panic::{RefUnwindSafe, UnwindSafe}; + use crate::thread; + + #[test] + fn stdout_unwind_safe() { + assert_unwind_safe::<Stdout>(); + } + #[test] + fn stdoutlock_unwind_safe() { + assert_unwind_safe::<StdoutLock<'_>>(); + assert_unwind_safe::<StdoutLock<'static>>(); + } + #[test] + fn stderr_unwind_safe() { + assert_unwind_safe::<Stderr>(); + } + #[test] + fn stderrlock_unwind_safe() { + assert_unwind_safe::<StderrLock<'_>>(); + assert_unwind_safe::<StderrLock<'static>>(); + } + + fn assert_unwind_safe<T: UnwindSafe + RefUnwindSafe>() {} + + #[test] + #[cfg_attr(target_os = "emscripten", ignore)] + fn panic_doesnt_poison() { + thread::spawn(|| { + let _a = stdin(); + let _a = _a.lock(); + let _a = stdout(); + let _a = _a.lock(); + let _a = stderr(); + let _a = _a.lock(); + panic!(); + }) + .join() + .unwrap_err(); + + let _a = stdin(); + let _a = _a.lock(); + let _a = stdout(); + let _a = _a.lock(); + let _a = stderr(); + let _a = _a.lock(); + } +} |