std: Add a new fs module

This commit is an implementation of [RFC 739][rfc] which adds a new `std::fs`
module to the standard library. This module provides much of the same
functionality as `std::old_io::fs` but it has many tweaked APIs as well as uses
the new `std::path` module.

[rfc]: rust-lang/rfcs#739

src/libstd/io/prelude.rs

@@ -22,6 +22,7 @@
 //! contained in this module.
 
 pub use super::{Read, ReadExt, Write, WriteExt, BufRead, BufReadExt};
+pub use fs::PathExt;
 
 // FIXME: pub use as `Seek` when the name isn't in the actual prelude any more
 pub use super::Seek as NewSeek;

src/libstd/lib.rs

@@ -248,6 +248,7 @@ pub mod ffi;
 pub mod fmt;
 pub mod old_io;
 pub mod io;
+pub mod fs;
 pub mod os;
 pub mod env;
 pub mod path;

src/libstd/path.rs

@@ -999,6 +999,12 @@ impl cmp::Ord for PathBuf {
     }
 }
 
+impl AsOsStr for PathBuf {
+    fn as_os_str(&self) -> &OsStr {
+        &self.inner[]
+    }
+}
+
 /// A slice of a path (akin to `str`).
 ///
 /// This type supports a number of operations for inspecting a path, including

src/libstd/sys/common/mod.rs

@@ -95,20 +95,30 @@ pub fn keep_going<F>(data: &[u8], mut f: F) -> i64 where
 }
 
 /// A trait for viewing representations from std types
+#[doc(hidden)]
 pub trait AsInner<Inner: ?Sized> {
     fn as_inner(&self) -> &Inner;
 }
 
+/// A trait for viewing representations from std types
+#[doc(hidden)]
+pub trait AsInnerMut<Inner: ?Sized> {
+    fn as_inner_mut(&mut self) -> &mut Inner;
+}
+
 /// A trait for extracting representations from std types
+#[doc(hidden)]
 pub trait IntoInner<Inner> {
     fn into_inner(self) -> Inner;
 }
 
 /// A trait for creating std types from internal representations
+#[doc(hidden)]
 pub trait FromInner<Inner> {
     fn from_inner(inner: Inner) -> Self;
 }
 
+#[doc(hidden)]
 pub trait ProcessConfig<K: BytesContainer, V: BytesContainer> {
     fn program(&self) -> &CString;
     fn args(&self) -> &[CString];

src/libstd/sys/unix/c.rs

@@ -149,6 +149,9 @@ extern {
                       buf: *mut libc::c_char,
                       buflen: libc::size_t,
                       result: *mut *mut passwd) -> libc::c_int;
+
+    pub fn utimes(filename: *const libc::c_char,
+                  times: *const libc::timeval) -> libc::c_int;
 }
 
 #[cfg(any(target_os = "macos", target_os = "ios"))]

src/libstd/sys/unix/ext.rs

@@ -31,11 +31,14 @@
 
 #![unstable(feature = "std_misc")]
 
-use vec::Vec;
-use sys::os_str::Buf;
-use sys_common::{AsInner, IntoInner, FromInner};
 use ffi::{OsStr, OsString};
+use fs::{Permissions, OpenOptions};
+use fs;
 use libc;
+use mem;
+use sys::os_str::Buf;
+use sys_common::{AsInner, AsInnerMut, IntoInner, FromInner};
+use vec::Vec;
 
 use old_io;
 
@@ -54,6 +57,12 @@ impl AsRawFd for old_io::fs::File {
     }
 }
 
+impl AsRawFd for fs::File {
+    fn as_raw_fd(&self) -> Fd {
+        self.as_inner().fd().raw()
+    }
+}
+
 impl AsRawFd for old_io::pipe::PipeStream {
     fn as_raw_fd(&self) -> Fd {
         self.as_inner().fd()
@@ -123,18 +132,49 @@ impl OsStringExt for OsString {
 
 // Unix-specific extensions to `OsStr`.
 pub trait OsStrExt {
+    fn from_byte_slice(slice: &[u8]) -> &OsStr;
     fn as_byte_slice(&self) -> &[u8];
 }
 
 impl OsStrExt for OsStr {
+    fn from_byte_slice(slice: &[u8]) -> &OsStr {
+        unsafe { mem::transmute(slice) }
+    }
     fn as_byte_slice(&self) -> &[u8] {
         &self.as_inner().inner
     }
 }
 
+// Unix-specific extensions to `Permissions`
+pub trait PermissionsExt {
+    fn set_mode(&mut self, mode: i32);
+}
+
+impl PermissionsExt for Permissions {
+    fn set_mode(&mut self, mode: i32) {
+        *self = FromInner::from_inner(FromInner::from_inner(mode));
+    }
+}
+
+// Unix-specific extensions to `OpenOptions`
+pub trait OpenOptionsExt {
+    /// Set the mode bits that a new file will be created with.
+    ///
+    /// If a new file is created as part of a `File::open_opts` call then this
+    /// specified `mode` will be used as the permission bits for the new file.
+    fn mode(&mut self, mode: i32) -> &mut Self;
+}
+
+impl OpenOptionsExt for OpenOptions {
+    fn mode(&mut self, mode: i32) -> &mut OpenOptions {
+        self.as_inner_mut().mode(mode); self
+    }
+}
+
 /// A prelude for conveniently writing platform-specific code.
 ///
 /// Includes all extension traits, and some important type definitions.
 pub mod prelude {
-    pub use super::{Fd, AsRawFd};
+    #[doc(no_inline)]
+    pub use super::{Fd, AsRawFd, OsStrExt, OsStringExt, PermissionsExt};
 }

src/libstd/sys/unix/fd.rs

@@ -0,0 +1,70 @@
+// 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 core::prelude::*;
+use io::prelude::*;
+
+use io;
+use libc::{self, c_int, size_t, c_void};
+use mem;
+use sys::cvt;
+
+pub type fd_t = c_int;
+
+pub struct FileDesc {
+    fd: c_int,
+}
+
+impl FileDesc {
+    pub fn new(fd: c_int) -> FileDesc {
+        FileDesc { fd: fd }
+    }
+
+    pub fn raw(&self) -> c_int { self.fd }
+
+    /// Extract the actual filedescriptor without closing it.
+    pub fn into_raw(self) -> c_int {
+        let fd = self.fd;
+        unsafe { mem::forget(self) };
+        fd
+    }
+
+    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        let ret = try!(cvt(unsafe {
+            libc::read(self.fd,
+                       buf.as_mut_ptr() as *mut c_void,
+                       buf.len() as size_t)
+        }));
+        Ok(ret as usize)
+    }
+
+    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
+        let ret = try!(cvt(unsafe {
+            libc::write(self.fd,
+                        buf.as_ptr() as *const c_void,
+                        buf.len() as size_t)
+        }));
+        Ok(ret as usize)
+    }
+}
+
+impl Drop for FileDesc {
+    fn drop(&mut self) {
+        // closing stdio file handles makes no sense, so never do it. Also, note
+        // that errors are ignored when closing a file descriptor. The reason
+        // for this is that if an error occurs we don't actually know if the
+        // file descriptor was closed or not, and if we retried (for something
+        // like EINTR), we might close another valid file descriptor (opened
+        // after we closed ours.
+        if self.fd > libc::STDERR_FILENO {
+            let _ = unsafe { libc::close(self.fd) };
+        }
+    }
+}