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Diffstat (limited to '')
-rw-r--r-- | library/std/src/io/stdio.rs | 1042 |
1 files changed, 1042 insertions, 0 deletions
diff --git a/library/std/src/io/stdio.rs b/library/std/src/io/stdio.rs new file mode 100644 index 000000000..4d3736f79 --- /dev/null +++ b/library/std/src/io/stdio.rs @@ -0,0 +1,1042 @@ +#![cfg_attr(test, allow(unused))] + +#[cfg(test)] +mod tests; + +use crate::io::prelude::*; + +use crate::cell::{Cell, RefCell}; +use crate::fmt; +use crate::io::{self, BufReader, IoSlice, IoSliceMut, LineWriter, Lines}; +use crate::pin::Pin; +use crate::sync::atomic::{AtomicBool, Ordering}; +use crate::sync::{Arc, Mutex, MutexGuard, OnceLock}; +use crate::sys::stdio; +use crate::sys_common::remutex::{ReentrantMutex, ReentrantMutexGuard}; + +type LocalStream = Arc<Mutex<Vec<u8>>>; + +thread_local! { + /// Used by the test crate to capture the output of the print macros and panics. + static OUTPUT_CAPTURE: Cell<Option<LocalStream>> = { + Cell::new(None) + } +} + +/// Flag to indicate OUTPUT_CAPTURE is used. +/// +/// If it is None and was never set on any thread, this flag is set to false, +/// and OUTPUT_CAPTURE can be safely ignored on all threads, saving some time +/// and memory registering an unused thread local. +/// +/// Note about memory ordering: This contains information about whether a +/// thread local variable might be in use. Although this is a global flag, the +/// memory ordering between threads does not matter: we only want this flag to +/// have a consistent order between set_output_capture and print_to *within +/// the same thread*. Within the same thread, things always have a perfectly +/// consistent order. So Ordering::Relaxed is fine. +static OUTPUT_CAPTURE_USED: AtomicBool = AtomicBool::new(false); + +/// 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. +#[unstable(feature = "libstd_sys_internals", issue = "none")] +const fn stdin_raw() -> StdinRaw { + StdinRaw(stdio::Stdin::new()) +} + +/// 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. +#[unstable(feature = "libstd_sys_internals", issue = "none")] +const fn stdout_raw() -> StdoutRaw { + StdoutRaw(stdio::Stdout::new()) +} + +/// 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. +#[unstable(feature = "libstd_sys_internals", issue = "none")] +const fn stderr_raw() -> StderrRaw { + StderrRaw(stdio::Stderr::new()) +} + +impl Read for StdinRaw { + fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { + handle_ebadf(self.0.read(buf), 0) + } + + fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> { + handle_ebadf(self.0.read_vectored(bufs), 0) + } + + #[inline] + fn is_read_vectored(&self) -> bool { + self.0.is_read_vectored() + } + + fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> { + handle_ebadf(self.0.read_to_end(buf), 0) + } + + fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> { + handle_ebadf(self.0.read_to_string(buf), 0) + } +} + +impl Write for StdoutRaw { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + handle_ebadf(self.0.write(buf), buf.len()) + } + + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + let total = bufs.iter().map(|b| b.len()).sum(); + handle_ebadf(self.0.write_vectored(bufs), total) + } + + #[inline] + fn is_write_vectored(&self) -> bool { + self.0.is_write_vectored() + } + + fn flush(&mut self) -> io::Result<()> { + handle_ebadf(self.0.flush(), ()) + } + + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + handle_ebadf(self.0.write_all(buf), ()) + } + + fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> { + handle_ebadf(self.0.write_all_vectored(bufs), ()) + } + + fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> { + handle_ebadf(self.0.write_fmt(fmt), ()) + } +} + +impl Write for StderrRaw { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + handle_ebadf(self.0.write(buf), buf.len()) + } + + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + let total = bufs.iter().map(|b| b.len()).sum(); + handle_ebadf(self.0.write_vectored(bufs), total) + } + + #[inline] + fn is_write_vectored(&self) -> bool { + self.0.is_write_vectored() + } + + fn flush(&mut self) -> io::Result<()> { + handle_ebadf(self.0.flush(), ()) + } + + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + handle_ebadf(self.0.write_all(buf), ()) + } + + fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> { + handle_ebadf(self.0.write_all_vectored(bufs), ()) + } + + fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> { + handle_ebadf(self.0.write_fmt(fmt), ()) + } +} + +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`]: stdin +/// +/// ### Note: Windows Portability Considerations +/// +/// 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. +/// +/// In a process with a detached console, such as one using +/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, +/// the contained handle will be null. In such cases, the standard library's `Read` and +/// `Write` will do nothing and silently succeed. All other I/O operations, via the +/// standard library or via raw Windows API calls, will fail. +/// +/// # Examples +/// +/// ```no_run +/// use std::io; +/// +/// fn main() -> io::Result<()> { +/// let mut buffer = String::new(); +/// let stdin = io::stdin(); // We get `Stdin` here. +/// stdin.read_line(&mut buffer)?; +/// Ok(()) +/// } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Stdin { + inner: &'static Mutex<BufReader<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. +/// +/// ### Note: Windows Portability Considerations +/// +/// 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. +/// +/// In a process with a detached console, such as one using +/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, +/// the contained handle will be null. In such cases, the standard library's `Read` and +/// `Write` will do nothing and silently succeed. All other I/O operations, via the +/// standard library or via raw Windows API calls, will fail. +/// +/// # Examples +/// +/// ```no_run +/// use std::io::{self, BufRead}; +/// +/// fn main() -> io::Result<()> { +/// let mut buffer = String::new(); +/// let stdin = io::stdin(); // We get `Stdin` here. +/// { +/// let mut handle = stdin.lock(); // We get `StdinLock` here. +/// handle.read_line(&mut buffer)?; +/// } // `StdinLock` is dropped here. +/// Ok(()) +/// } +/// ``` +#[must_use = "if unused stdin will immediately unlock"] +#[stable(feature = "rust1", since = "1.0.0")] +pub struct StdinLock<'a> { + inner: MutexGuard<'a, BufReader<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. +/// +/// ### Note: Windows Portability Considerations +/// +/// 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. +/// +/// In a process with a detached console, such as one using +/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, +/// the contained handle will be null. In such cases, the standard library's `Read` and +/// `Write` will do nothing and silently succeed. All other I/O operations, via the +/// standard library or via raw Windows API calls, will fail. +/// +/// # Examples +/// +/// Using implicit synchronization: +/// +/// ```no_run +/// use std::io; +/// +/// fn main() -> io::Result<()> { +/// let mut buffer = String::new(); +/// io::stdin().read_line(&mut buffer)?; +/// Ok(()) +/// } +/// ``` +/// +/// Using explicit synchronization: +/// +/// ```no_run +/// use std::io::{self, BufRead}; +/// +/// fn main() -> io::Result<()> { +/// let mut buffer = String::new(); +/// let stdin = io::stdin(); +/// let mut handle = stdin.lock(); +/// +/// handle.read_line(&mut buffer)?; +/// Ok(()) +/// } +/// ``` +#[must_use] +#[stable(feature = "rust1", since = "1.0.0")] +pub fn stdin() -> Stdin { + static INSTANCE: OnceLock<Mutex<BufReader<StdinRaw>>> = OnceLock::new(); + Stdin { + inner: INSTANCE.get_or_init(|| { + Mutex::new(BufReader::with_capacity(stdio::STDIN_BUF_SIZE, stdin_raw())) + }), + } +} + +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. + /// + /// # Examples + /// + /// ```no_run + /// use std::io::{self, BufRead}; + /// + /// fn main() -> io::Result<()> { + /// let mut buffer = String::new(); + /// let stdin = io::stdin(); + /// let mut handle = stdin.lock(); + /// + /// handle.read_line(&mut buffer)?; + /// Ok(()) + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn lock(&self) -> StdinLock<'static> { + // Locks this handle with 'static lifetime. This depends on the + // implementation detail that the underlying `Mutex` is static. + 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`]. + /// + /// # Examples + /// + /// ```no_run + /// use std::io; + /// + /// let mut input = String::new(); + /// match io::stdin().read_line(&mut input) { + /// Ok(n) => { + /// println!("{n} bytes read"); + /// 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) + } + + /// Consumes this handle and returns an iterator over input lines. + /// + /// For detailed semantics of this method, see the documentation on + /// [`BufRead::lines`]. + /// + /// # Examples + /// + /// ```no_run + /// use std::io; + /// + /// let lines = io::stdin().lines(); + /// for line in lines { + /// println!("got a line: {}", line.unwrap()); + /// } + /// ``` + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "stdin_forwarders", since = "1.62.0")] + pub fn lines(self) -> Lines<StdinLock<'static>> { + self.lock().lines() + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for Stdin { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("Stdin").finish_non_exhaustive() + } +} + +#[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() + } + 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) + } +} + +// only used by platform-dependent io::copy specializations, i.e. unused on some platforms +#[cfg(any(target_os = "linux", target_os = "android"))] +impl StdinLock<'_> { + pub(crate) fn as_mut_buf(&mut self) -> &mut BufReader<impl Read> { + &mut self.inner + } +} + +#[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() + } + + 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.debug_struct("StdinLock").finish_non_exhaustive() + } +} + +/// 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 Considerations +/// +/// 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. +/// +/// In a process with a detached console, such as one using +/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, +/// the contained handle will be null. In such cases, the standard library's `Read` and +/// `Write` will do nothing and silently succeed. All other I/O operations, via the +/// standard library or via raw Windows API calls, will fail. +/// +/// [`lock`]: Stdout::lock +/// [`io::stdout`]: stdout +#[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: Pin<&'static ReentrantMutex<RefCell<LineWriter<StdoutRaw>>>>, +} + +/// A locked reference to the [`Stdout`] handle. +/// +/// This handle implements the [`Write`] trait, and is constructed via +/// the [`Stdout::lock`] method. See its documentation for more. +/// +/// ### Note: Windows Portability Considerations +/// +/// 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. +/// +/// In a process with a detached console, such as one using +/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, +/// the contained handle will be null. In such cases, the standard library's `Read` and +/// `Write` will do nothing and silently succeed. All other I/O operations, via the +/// standard library or via raw Windows API calls, will fail. +#[must_use = "if unused stdout will immediately unlock"] +#[stable(feature = "rust1", since = "1.0.0")] +pub struct StdoutLock<'a> { + inner: ReentrantMutexGuard<'a, RefCell<LineWriter<StdoutRaw>>>, +} + +static STDOUT: OnceLock<ReentrantMutex<RefCell<LineWriter<StdoutRaw>>>> = OnceLock::new(); + +/// 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. +/// +/// ### Note: Windows Portability Considerations +/// +/// 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. +/// +/// In a process with a detached console, such as one using +/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, +/// the contained handle will be null. In such cases, the standard library's `Read` and +/// `Write` will do nothing and silently succeed. All other I/O operations, via the +/// standard library or via raw Windows API calls, will fail. +/// +/// # 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(()) +/// } +/// ``` +#[must_use] +#[stable(feature = "rust1", since = "1.0.0")] +pub fn stdout() -> Stdout { + Stdout { + inner: Pin::static_ref(&STDOUT).get_or_init_pin( + || unsafe { ReentrantMutex::new(RefCell::new(LineWriter::new(stdout_raw()))) }, + |mutex| unsafe { mutex.init() }, + ), + } +} + +pub fn cleanup() { + if let Some(instance) = STDOUT.get() { + // Flush the data and disable buffering during shutdown + // by replacing the line writer by one with zero + // buffering capacity. + // We use try_lock() instead of lock(), because someone + // might have leaked a StdoutLock, which would + // otherwise cause a deadlock here. + if let Some(lock) = Pin::static_ref(instance).try_lock() { + *lock.borrow_mut() = LineWriter::with_capacity(0, stdout_raw()); + } + } +} + +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 mut stdout = io::stdout().lock(); + /// + /// stdout.write_all(b"hello world")?; + /// + /// Ok(()) + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn lock(&self) -> StdoutLock<'static> { + // Locks this handle with 'static lifetime. This depends on the + // implementation detail that the underlying `ReentrantMutex` is + // static. + 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.debug_struct("Stdout").finish_non_exhaustive() + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Write for Stdout { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + (&*self).write(buf) + } + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + (&*self).write_vectored(bufs) + } + #[inline] + fn is_write_vectored(&self) -> bool { + io::Write::is_write_vectored(&&*self) + } + fn flush(&mut self) -> io::Result<()> { + (&*self).flush() + } + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + (&*self).write_all(buf) + } + fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> { + (&*self).write_all_vectored(bufs) + } + fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> { + (&*self).write_fmt(args) + } +} + +#[stable(feature = "write_mt", since = "1.48.0")] +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.debug_struct("StdoutLock").finish_non_exhaustive() + } +} + +/// A handle to the standard error stream of a process. +/// +/// For more information, see the [`io::stderr`] method. +/// +/// [`io::stderr`]: stderr +/// +/// ### Note: Windows Portability Considerations +/// +/// 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. +/// +/// In a process with a detached console, such as one using +/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, +/// the contained handle will be null. In such cases, the standard library's `Read` and +/// `Write` will do nothing and silently succeed. All other I/O operations, via the +/// standard library or via raw Windows API calls, will fail. +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Stderr { + inner: Pin<&'static ReentrantMutex<RefCell<StderrRaw>>>, +} + +/// A locked reference to the [`Stderr`] handle. +/// +/// This handle implements the [`Write`] trait and is constructed via +/// the [`Stderr::lock`] method. See its documentation for more. +/// +/// ### Note: Windows Portability Considerations +/// +/// 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. +/// +/// In a process with a detached console, such as one using +/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, +/// the contained handle will be null. In such cases, the standard library's `Read` and +/// `Write` will do nothing and silently succeed. All other I/O operations, via the +/// standard library or via raw Windows API calls, will fail. +#[must_use = "if unused stderr will immediately unlock"] +#[stable(feature = "rust1", since = "1.0.0")] +pub struct StderrLock<'a> { + inner: ReentrantMutexGuard<'a, RefCell<StderrRaw>>, +} + +/// Constructs a new handle to the standard error of the current process. +/// +/// This handle is not buffered. +/// +/// ### Note: Windows Portability Considerations +/// +/// 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. +/// +/// In a process with a detached console, such as one using +/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, +/// the contained handle will be null. In such cases, the standard library's `Read` and +/// `Write` will do nothing and silently succeed. All other I/O operations, via the +/// standard library or via raw Windows API calls, will fail. +/// +/// # 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(()) +/// } +/// ``` +#[must_use] +#[stable(feature = "rust1", since = "1.0.0")] +pub fn stderr() -> Stderr { + // Note that unlike `stdout()` we don't use `at_exit` here to register a + // destructor. Stderr is not buffered , so there's no need to run a + // destructor for flushing the buffer + static INSTANCE: OnceLock<ReentrantMutex<RefCell<StderrRaw>>> = OnceLock::new(); + + Stderr { + inner: Pin::static_ref(&INSTANCE).get_or_init_pin( + || unsafe { ReentrantMutex::new(RefCell::new(stderr_raw())) }, + |mutex| unsafe { mutex.init() }, + ), + } +} + +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<'static> { + // Locks this handle with 'static lifetime. This depends on the + // implementation detail that the underlying `ReentrantMutex` is + // static. + 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.debug_struct("Stderr").finish_non_exhaustive() + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Write for Stderr { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + (&*self).write(buf) + } + fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { + (&*self).write_vectored(bufs) + } + #[inline] + fn is_write_vectored(&self) -> bool { + io::Write::is_write_vectored(&&*self) + } + fn flush(&mut self) -> io::Result<()> { + (&*self).flush() + } + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + (&*self).write_all(buf) + } + fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> { + (&*self).write_all_vectored(bufs) + } + fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> { + (&*self).write_fmt(args) + } +} + +#[stable(feature = "write_mt", since = "1.48.0")] +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.debug_struct("StderrLock").finish_non_exhaustive() + } +} + +/// Sets the thread-local output capture buffer and returns the old one. +#[unstable( + feature = "internal_output_capture", + reason = "this function is meant for use in the test crate \ + and may disappear in the future", + issue = "none" +)] +#[doc(hidden)] +pub fn set_output_capture(sink: Option<LocalStream>) -> Option<LocalStream> { + if sink.is_none() && !OUTPUT_CAPTURE_USED.load(Ordering::Relaxed) { + // OUTPUT_CAPTURE is definitely None since OUTPUT_CAPTURE_USED is false. + return None; + } + OUTPUT_CAPTURE_USED.store(true, Ordering::Relaxed); + OUTPUT_CAPTURE.with(move |slot| slot.replace(sink)) +} + +/// Write `args` to the capture buffer if enabled and possible, or `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<'_>, global_s: fn() -> T, label: &str) +where + T: Write, +{ + if OUTPUT_CAPTURE_USED.load(Ordering::Relaxed) + && OUTPUT_CAPTURE.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. + s.take().map(|w| { + let _ = w.lock().unwrap_or_else(|e| e.into_inner()).write_fmt(args); + s.set(Some(w)); + }) + }) == Ok(Some(())) + { + // Successfully wrote to capture buffer. + return; + } + + if let Err(e) = global_s().write_fmt(args) { + 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, 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, stderr, "stderr"); +} + +#[cfg(test)] +pub use realstd::io::{_eprint, _print}; |