std: Implement stdio for `std::io`

This is an implementation of RFC 899 and adds stdio functionality to the new
`std::io` module. Details of the API can be found on the RFC, but from a high
level:

* `io::{stdin, stdout, stderr}` constructors are now available. There are also
  `*_raw` variants for unbuffered and unlocked access.
* All handles are globally shared (excluding raw variants).
* The stderr handle is no longer buffered.
* All handles can be explicitly locked (excluding the raw variants).

The `print!` and `println!` machinery has not yet been hooked up to these
streams just yet. The `std::fmt::output` module has also not yet been
implemented as part of this commit.

3 files changed, 389 insertions, 0 deletions

diff --git a/src/libstd/io/lazy.rs b/src/libstd/io/lazy.rs
new file mode 100644
index 00000000000..c9b105f72a5
--- /dev/null
+++ b/src/libstd/io/lazy.rs
@@ -0,0 +1,59 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use prelude::v1::*;
+
+use boxed;
+use cell::UnsafeCell;
+use rt;
+use sync::{StaticMutex, Arc};
+
+pub struct Lazy<T> {
+    pub lock: StaticMutex,
+    pub ptr: UnsafeCell<*mut Arc<T>>,
+    pub init: fn() -> Arc<T>,
+}
+
+unsafe impl<T> Sync for Lazy<T> {}
+
+macro_rules! lazy_init {
+    ($init:expr) => (::io::lazy::Lazy {
+        lock: ::sync::MUTEX_INIT,
+        ptr: ::cell::UnsafeCell { value: 0 as *mut _ },
+        init: $init,
+    })
+}
+
+impl<T: Send + Sync + 'static> Lazy<T> {
+    pub fn get(&'static self) -> Option<Arc<T>> {
+        let _g = self.lock.lock();
+        unsafe {
+            let mut ptr = *self.ptr.get();
+            if ptr.is_null() {
+                ptr = boxed::into_raw(self.init());
+                *self.ptr.get() = ptr;
+            } else if ptr as usize == 1 {
+                return None
+            }
+            Some((*ptr).clone())
+        }
+    }
+
+    fn init(&'static self) -> Box<Arc<T>> {
+        rt::at_exit(move || unsafe {
+            let g = self.lock.lock();
+            let ptr = *self.ptr.get();
+            *self.ptr.get() = 1 as *mut _;
+            drop(g);
+            drop(Box::from_raw(ptr))
+        });
+        Box::new((self.init)())
+    }
+}
diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 3b4e15953c4..5510c0203e6 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -39,6 +39,10 @@ pub use self::buffered::IntoInnerError;
 pub use self::cursor::Cursor;
 pub use self::error::{Result, Error, ErrorKind};
 pub use self::util::{copy, sink, Sink, empty, Empty, repeat, Repeat};
+pub use self::stdio::{stdin, stdout, stderr, Stdin, Stdout, Stderr};
+pub use self::stdio::{StdoutLock, StderrLock, StdinLock};
+
+#[macro_use] mod lazy;
 
 pub mod prelude;
 mod buffered;
@@ -46,6 +50,7 @@ mod cursor;
 mod error;
 mod impls;
 mod util;
+mod stdio;
 
 const DEFAULT_BUF_SIZE: usize = 64 * 1024;
 
diff --git a/src/libstd/io/stdio.rs b/src/libstd/io/stdio.rs
new file mode 100644
index 00000000000..61ad9905771
--- /dev/null
+++ b/src/libstd/io/stdio.rs
@@ -0,0 +1,325 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use prelude::v1::*;
+use io::prelude::*;
+
+use cmp;
+use fmt;
+use io::lazy::Lazy;
+use io::{self, BufReader, LineWriter};
+use sync::{Arc, Mutex, MutexGuard};
+use sys::stdio;
+
+/// 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::stdin_raw` function.
+pub 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::stdout_raw` function.
+pub 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::stderr_raw` function.
+pub struct StderrRaw(stdio::Stderr);
+
+/// Construct 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.
+pub fn stdin_raw() -> StdinRaw { StdinRaw(stdio::Stdin::new()) }
+
+/// Construct a new raw handle to the standard input 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::stdin` 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.
+pub fn stdout_raw() -> StdoutRaw { StdoutRaw(stdio::Stdout::new()) }
+
+/// Construct a new raw handle to the standard input stream of this process.
+///
+/// The returned handle does not interact with any other handles created nor
+/// handles returned by `std::io::stdout`.
+///
+/// The returned handle has no external synchronization or buffering layered on
+/// top.
+pub fn stderr_raw() -> StderrRaw { StderrRaw(stdio::Stderr::new()) }
+
+impl Read for StdinRaw {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { self.0.read(buf) }
+}
+impl Write for StdoutRaw {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> { self.0.write(buf) }
+    fn flush(&mut self) -> io::Result<()> { Ok(()) }
+}
+impl Write for StderrRaw {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> { self.0.write(buf) }
+    fn flush(&mut self) -> io::Result<()> { Ok(()) }
+}
+
+/// 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()`). Writes to this handle are otherwise locked with respect
+/// to other writes.
+///
+/// This handle implements the `Read` trait, but beware that concurrent reads
+/// of `Stdin` must be executed with care.
+pub struct Stdin {
+    inner: Arc<Mutex<BufReader<StdinRaw>>>,
+}
+
+/// A locked reference to the a `Stdin` handle.
+///
+/// This handle implements both the `Read` and `BufRead` traits and is
+/// constructed via the `lock` method on `Stdin`.
+pub struct StdinLock<'a> {
+    inner: MutexGuard<'a, BufReader<StdinRaw>>,
+}
+
+/// Create a new handle to the global standard input stream of this process.
+///
+/// The handle returned refers to a globally shared buffer between all threads.
+/// Access is synchronized and can be explicitly controlled with the `lock()`
+/// method.
+///
+/// The `Read` trait is implemented for the returned value but the `BufRead`
+/// trait is not due to the global nature of the standard input stream. The
+/// locked version, `StdinLock`, implements both `Read` and `BufRead`, however.
+///
+/// To avoid locking and buffering altogether, it is recommended to use the
+/// `stdin_raw` constructor.
+pub fn stdin() -> Stdin {
+    static INSTANCE: Lazy<Mutex<BufReader<StdinRaw>>> = lazy_init!(stdin_init);
+    return Stdin {
+        inner: INSTANCE.get().expect("cannot access stdin during shutdown"),
+    };
+
+    fn stdin_init() -> Arc<Mutex<BufReader<StdinRaw>>> {
+        // The default buffer capacity is 64k, but apparently windows
+        // doesn't like 64k reads on stdin. See #13304 for details, but the
+        // idea is that on windows we use a slightly smaller buffer that's
+        // been seen to be acceptable.
+        Arc::new(Mutex::new(if cfg!(windows) {
+            BufReader::with_capacity(8 * 1024, stdin_raw())
+        } else {
+            BufReader::new(stdin_raw())
+        }))
+    }
+}
+
+impl Stdin {
+    /// Lock 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.
+    pub fn lock(&self) -> StdinLock {
+        StdinLock { inner: self.inner.lock().unwrap() }
+    }
+}
+
+impl Read for Stdin {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.lock().read(buf)
+    }
+
+    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<()> {
+        self.lock().read_to_end(buf)
+    }
+
+    fn read_to_string(&mut self, buf: &mut String) -> io::Result<()> {
+        self.lock().read_to_string(buf)
+    }
+}
+
+impl<'a> Read for StdinLock<'a> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        // Flush stdout so that weird issues like a print!'d prompt not being
+        // shown until after the user hits enter.
+        drop(stdout().flush());
+        self.inner.read(buf)
+    }
+}
+impl<'a> BufRead for StdinLock<'a> {
+    fn fill_buf(&mut self) -> io::Result<&[u8]> { self.inner.fill_buf() }
+    fn consume(&mut self, n: usize) { self.inner.consume(n) }
+}
+
+// As with stdin on windows, stdout often can't handle writes of large
+// sizes. For an example, see #14940. For this reason, don't try to
+// write the entire output buffer on windows. On unix we can just
+// write the whole buffer all at once.
+//
+// For some other references, it appears that this problem has been
+// encountered by others [1] [2]. We choose the number 8KB just because
+// libuv does the same.
+//
+// [1]: https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1232
+// [2]: http://www.mail-archive.com/log4net-dev@logging.apache.org/msg00661.html
+#[cfg(windows)]
+const OUT_MAX: usize = 8192;
+#[cfg(unix)]
+const OUT_MAX: usize = ::usize::MAX;
+
+/// 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.
+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<Mutex<LineWriter<StdoutRaw>>>,
+}
+
+/// A locked reference to the a `Stdout` handle.
+///
+/// This handle implements the `Write` trait and is constructed via the `lock`
+/// method on `Stdout`.
+pub struct StdoutLock<'a> {
+    inner: MutexGuard<'a, LineWriter<StdoutRaw>>,
+}
+
+/// Constructs a new reference 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. Explicit control over synchronization is
+/// provided via the `lock` method.
+///
+/// The returned handle implements the `Write` trait.
+///
+/// To avoid locking and buffering altogether, it is recommended to use the
+/// `stdout_raw` constructor.
+pub fn stdout() -> Stdout {
+    static INSTANCE: Lazy<Mutex<LineWriter<StdoutRaw>>> = lazy_init!(stdout_init);
+    return Stdout {
+        inner: INSTANCE.get().expect("cannot access stdout during shutdown"),
+    };
+
+    fn stdout_init() -> Arc<Mutex<LineWriter<StdoutRaw>>> {
+        Arc::new(Mutex::new(LineWriter::new(stdout_raw())))
+    }
+}
+
+impl Stdout {
+    /// Lock 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.
+    pub fn lock(&self) -> StdoutLock {
+        StdoutLock { inner: self.inner.lock().unwrap() }
+    }
+}
+
+impl Write for Stdout {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.lock().write(buf)
+    }
+    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_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
+        self.lock().write_fmt(fmt)
+    }
+}
+impl<'a> Write for StdoutLock<'a> {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.write(&buf[..cmp::min(buf.len(), OUT_MAX)])
+    }
+    fn flush(&mut self) -> io::Result<()> { self.inner.flush() }
+}
+
+/// A handle to the standard error stream of a process.
+///
+/// For more information, see `stderr`
+pub struct Stderr {
+    inner: Arc<Mutex<StderrRaw>>,
+}
+
+/// A locked reference to the a `Stderr` handle.
+///
+/// This handle implements the `Write` trait and is constructed via the `lock`
+/// method on `Stderr`.
+pub struct StderrLock<'a> {
+    inner: MutexGuard<'a, StderrRaw>,
+}
+
+/// Constructs a new reference to the standard error stream of a process.
+///
+/// Each returned handle is synchronized amongst all other handles created from
+/// this function. No handles are buffered, however.
+///
+/// The returned handle implements the `Write` trait.
+///
+/// To avoid locking altogether, it is recommended to use the `stderr_raw`
+/// constructor.
+pub fn stderr() -> Stderr {
+    static INSTANCE: Lazy<Mutex<StderrRaw>> = lazy_init!(stderr_init);
+    return Stderr {
+        inner: INSTANCE.get().expect("cannot access stderr during shutdown"),
+    };
+
+    fn stderr_init() -> Arc<Mutex<StderrRaw>> {
+        Arc::new(Mutex::new(stderr_raw()))
+    }
+}
+
+impl Stderr {
+    /// Lock 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.
+    pub fn lock(&self) -> StderrLock {
+        StderrLock { inner: self.inner.lock().unwrap() }
+    }
+}
+
+impl Write for Stderr {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.lock().write(buf)
+    }
+    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_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
+        self.lock().write_fmt(fmt)
+    }
+}
+impl<'a> Write for StderrLock<'a> {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.write(&buf[..cmp::min(buf.len(), OUT_MAX)])
+    }
+    fn flush(&mut self) -> io::Result<()> { self.inner.flush() }
+}