rollup merge of #24873: alexcrichton/fix-windows-stdio

Conflicts:
	src/libstd/sys/windows/fs2.rs

diff --cc src/libstd/sys/windows/fs2.rs
index 5b748280986f7258bb4ff1ab64ad03491b4e0c36,1c47176173ade1d91c0d4380d7f2b07bf8633918..03a56e2958a6e9f485b050323ac42274b744b9eb
--- 1/src/libstd/sys/windows/fs2.rs
--- 2/src/libstd/sys/windows/fs2.rs
+++ b/src/libstd/sys/windows/fs2.rs
@@@ -310,40 -268,7 +314,42 @@@ impl File 
  
      pub fn handle(&self) -> &Handle { &self.handle }
  
 +    fn is_symlink(&self) -> bool {
 +        self.readlink().is_ok()
 +    }
 +
 +    fn readlink(&self) -> io::Result<PathBuf> {
 +        let mut space = [0u8; c::MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
 +        let mut bytes = 0;
 +
 +        unsafe {
 +            try!(cvt({
 +                c::DeviceIoControl(self.handle.raw(),
 +                                   c::FSCTL_GET_REPARSE_POINT,
 +                                   0 as *mut _,
 +                                   0,
 +                                   space.as_mut_ptr() as *mut _,
 +                                   space.len() as libc::DWORD,
 +                                   &mut bytes,
 +                                   0 as *mut _)
 +            }));
 +            let buf: *const c::REPARSE_DATA_BUFFER = space.as_ptr() as *const _;
 +            if (*buf).ReparseTag != c::IO_REPARSE_TAG_SYMLINK {
 +                return Err(io::Error::new(io::ErrorKind::Other, "not a symlink"))
 +            }
 +            let info: *const c::SYMBOLIC_LINK_REPARSE_BUFFER =
 +                    &(*buf).rest as *const _ as *const _;
 +            let path_buffer = &(*info).PathBuffer as *const _ as *const u16;
 +            let subst_off = (*info).SubstituteNameOffset / 2;
 +            let subst_ptr = path_buffer.offset(subst_off as isize);
 +            let subst_len = (*info).SubstituteNameLength / 2;
 +            let subst = slice::from_raw_parts(subst_ptr, subst_len as usize);
 +
 +            Ok(PathBuf::from(OsString::from_wide(subst)))
 +        }
 +    }
++
+     pub fn into_handle(self) -> Handle { self.handle }
  }
  
  impl FromInner<libc::HANDLE> for File {