Rollup merge of #22727 - alexcrichton:prep-env, r=aturon

This commit moves `std::env` away from the `std::old_io` error type as well as
the `std::old_path` module. Methods returning an error now return `io::Error`
and methods consuming or returning paths use `std::path` instead of
`std::old_path`. This commit does not yet mark these APIs as `#[stable]`.

This commit also migrates `std::old_io::TempDir` to `std::fs::TempDir` with
essentially the exact same API. This type was added to interoperate with the new
path API and has its own `tempdir` feature.

Finally, this commit reverts the deprecation of `std::os` APIs returning the old
path API types. This deprecation can come back once the entire `std::old_path`
module is deprecated.

[breaking-change]

src/libstd/sys/unix/backtrace.rs

@@ -84,8 +84,9 @@
 /// all unix platforms we support right now, so it at least gets the job done.
 
 use prelude::v1::*;
+use os::unix::prelude::*;
 
-use ffi::CStr;
+use ffi::{CStr, AsOsStr};
 use old_io::IoResult;
 use libc;
 use mem;
@@ -327,7 +328,7 @@ fn print(w: &mut Writer, idx: int, addr: *mut libc::c_void) -> IoResult<()> {
         };
         let filename = match selfname {
             Some(path) => {
-                let bytes = path.as_vec();
+                let bytes = path.as_os_str().as_bytes();
                 if bytes.len() < LAST_FILENAME.len() {
                     let i = bytes.iter();
                     for (slot, val) in LAST_FILENAME.iter_mut().zip(i) {

src/libstd/sys/unix/os.rs

@@ -16,12 +16,13 @@ use os::unix::*;
 use error::Error as StdError;
 use ffi::{CString, CStr, OsString, OsStr, AsOsStr};
 use fmt;
+use io;
 use iter;
 use libc::{self, c_int, c_char, c_void};
 use mem;
-use io;
-use old_io::{IoResult, IoError, fs};
+use old_io::{IoError, IoResult};
 use ptr;
+use path::{self, PathBuf};
 use slice;
 use str;
 use sys::c;
@@ -32,6 +33,14 @@ use vec;
 const BUF_BYTES: usize = 2048;
 const TMPBUF_SZ: usize = 128;
 
+fn bytes2path(b: &[u8]) -> PathBuf {
+    PathBuf::new(<OsStr as OsStrExt>::from_bytes(b))
+}
+
+fn os2path(os: OsString) -> PathBuf {
+    bytes2path(os.as_bytes())
+}
+
 /// Returns the platform-specific value of errno
 pub fn errno() -> i32 {
     #[cfg(any(target_os = "macos",
@@ -102,30 +111,30 @@ pub fn error_string(errno: i32) -> String {
     }
 }
 
-pub fn getcwd() -> IoResult<Path> {
+pub fn getcwd() -> io::Result<PathBuf> {
     let mut buf = [0 as c_char; BUF_BYTES];
     unsafe {
         if libc::getcwd(buf.as_mut_ptr(), buf.len() as libc::size_t).is_null() {
-            Err(IoError::last_error())
+            Err(io::Error::last_os_error())
         } else {
-            Ok(Path::new(CStr::from_ptr(buf.as_ptr()).to_bytes()))
+            Ok(bytes2path(CStr::from_ptr(buf.as_ptr()).to_bytes()))
         }
     }
 }
 
-pub fn chdir(p: &Path) -> IoResult<()> {
-    let p = CString::new(p.as_vec()).unwrap();
+pub fn chdir(p: &path::Path) -> io::Result<()> {
+    let p = try!(CString::new(p.as_os_str().as_bytes()));
     unsafe {
         match libc::chdir(p.as_ptr()) == (0 as c_int) {
             true => Ok(()),
-            false => Err(IoError::last_error()),
+            false => Err(io::Error::last_os_error()),
         }
     }
 }
 
 pub struct SplitPaths<'a> {
     iter: iter::Map<slice::Split<'a, u8, fn(&u8) -> bool>,
-                    fn(&'a [u8]) -> Path>,
+                    fn(&'a [u8]) -> PathBuf>,
 }
 
 pub fn split_paths<'a>(unparsed: &'a OsStr) -> SplitPaths<'a> {
@@ -133,13 +142,13 @@ pub fn split_paths<'a>(unparsed: &'a OsStr) -> SplitPaths<'a> {
     let unparsed = unparsed.as_bytes();
     SplitPaths {
         iter: unparsed.split(is_colon as fn(&u8) -> bool)
-                      .map(Path::new as fn(&'a [u8]) ->  Path)
+                      .map(bytes2path as fn(&'a [u8]) -> PathBuf)
     }
 }
 
 impl<'a> Iterator for SplitPaths<'a> {
-    type Item = Path;
-    fn next(&mut self) -> Option<Path> { self.iter.next() }
+    type Item = PathBuf;
+    fn next(&mut self) -> Option<PathBuf> { self.iter.next() }
     fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
 }
 
@@ -200,12 +209,12 @@ pub fn current_exe() -> IoResult<Path> {
 }
 
 #[cfg(target_os = "dragonfly")]
-pub fn current_exe() -> IoResult<Path> {
-    fs::readlink(&Path::new("/proc/curproc/file"))
+pub fn current_exe() -> io::Result<PathBuf> {
+    ::fs::read_link("/proc/curproc/file")
 }
 
 #[cfg(any(target_os = "bitrig", target_os = "openbsd"))]
-pub fn current_exe() -> IoResult<Path> {
+pub fn current_exe() -> io::Result<PathBuf> {
     use sync::{StaticMutex, MUTEX_INIT};
     static LOCK: StaticMutex = MUTEX_INIT;
 
@@ -226,8 +235,8 @@ pub fn current_exe() -> IoResult<Path> {
 }
 
 #[cfg(any(target_os = "linux", target_os = "android"))]
-pub fn current_exe() -> IoResult<Path> {
-    fs::readlink(&Path::new("/proc/self/exe"))
+pub fn current_exe() -> io::Result<PathBuf> {
+    ::fs::read_link("/proc/self/exe")
 }
 
 #[cfg(any(target_os = "macos", target_os = "ios"))]
@@ -451,22 +460,20 @@ pub fn page_size() -> usize {
     }
 }
 
-pub fn temp_dir() -> Path {
-    getenv("TMPDIR".as_os_str()).map(|p| Path::new(p.into_vec())).unwrap_or_else(|| {
+pub fn temp_dir() -> PathBuf {
+    getenv("TMPDIR".as_os_str()).map(os2path).unwrap_or_else(|| {
         if cfg!(target_os = "android") {
-            Path::new("/data/local/tmp")
+            PathBuf::new("/data/local/tmp")
         } else {
-            Path::new("/tmp")
+            PathBuf::new("/tmp")
         }
     })
 }
 
-pub fn home_dir() -> Option<Path> {
+pub fn home_dir() -> Option<PathBuf> {
     return getenv("HOME".as_os_str()).or_else(|| unsafe {
         fallback()
-    }).map(|os| {
-        Path::new(os.into_vec())
-    });
+    }).map(os2path);
 
     #[cfg(any(target_os = "android",
               target_os = "ios"))]