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.

1 files changed, 13 insertions, 10 deletions

diff --git a/src/liballoc/arc.rs b/src/liballoc/arc.rs
index 88a3752c88a..c95b413b397 100644
--- a/src/liballoc/arc.rs
+++ b/src/liballoc/arc.rs
@@ -201,10 +201,11 @@ impl<T> Arc<T> {
 impl<T> Arc<T> {
     #[inline]
     fn inner(&self) -> &ArcInner<T> {
-        // This unsafety is ok because while this arc is alive we're guaranteed that the inner
-        // pointer is valid. Furthermore, we know that the `ArcInner` structure itself is `Sync`
-        // because the inner data is `Sync` as well, so we're ok loaning out an immutable pointer
-        // to these contents.
+        // This unsafety is ok because while this arc is alive we're guaranteed
+        // that the inner pointer is valid. Furthermore, we know that the
+        // `ArcInner` structure itself is `Sync` because the inner data is
+        // `Sync` as well, so we're ok loaning out an immutable pointer to these
+        // contents.
         unsafe { &**self._ptr }
     }
 }
@@ -236,13 +237,15 @@ impl<T> Clone for Arc<T> {
     /// ```
     #[inline]
     fn clone(&self) -> Arc<T> {
-        // Using a relaxed ordering is alright here, as knowledge of the original reference
-        // prevents other threads from erroneously deleting the object.
+        // Using a relaxed ordering is alright here, as knowledge of the
+        // original reference prevents other threads from erroneously deleting
+        // the object.
         //
-        // As explained in the [Boost documentation][1], Increasing the reference counter can
-        // always be done with memory_order_relaxed: New references to an object can only be formed
-        // from an existing reference, and passing an existing reference from one thread to another
-        // must already provide any required synchronization.
+        // As explained in the [Boost documentation][1], Increasing the
+        // reference counter can always be done with memory_order_relaxed: New
+        // references to an object can only be formed from an existing
+        // reference, and passing an existing reference from one thread to
+        // another must already provide any required synchronization.
         //
         // [1]: (www.boost.org/doc/libs/1_55_0/doc/html/atomic/usage_examples.html)
         self.inner().strong.fetch_add(1, Relaxed);