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    // 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.

    //! Filesystem manipulation operations.
    //!
    //! This module contains basic methods to manipulate the contents of the local
    //! filesystem. All methods in this module represent cross-platform filesystem
    //! operations. Extra platform-specific functionality can be found in the
    //! extension traits of `std::os::$platform`.

    #![stable(feature = "rust1", since = "1.0.0")]

    use fmt;
    use ffi::OsString;
    use io::{self, SeekFrom, Seek, Read, Write};
    use path::{Path, PathBuf};
    use sys::fs as fs_imp;
    use sys_common::{AsInnerMut, FromInner, AsInner, IntoInner};
    use vec::Vec;
    use time::SystemTime;

    /// A reference to an open file on the filesystem.
    ///
    /// An instance of a `File` can be read and/or written depending on what options
    /// it was opened with. Files also implement `Seek` to alter the logical cursor
    /// that the file contains internally.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::io::prelude::*;
    /// use std::fs::File;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// let mut f = try!(File::create("foo.txt"));
    /// try!(f.write_all(b"Hello, world!"));
    ///
    /// let mut f = try!(File::open("foo.txt"));
    /// let mut s = String::new();
    /// try!(f.read_to_string(&mut s));
    /// assert_eq!(s, "Hello, world!");
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub struct File {
        inner: fs_imp::File,
    }

    /// Metadata information about a file.
    ///
    /// This structure is returned from the `metadata` function or method and
    /// represents known metadata about a file such as its permissions, size,
    /// modification times, etc.
    #[stable(feature = "rust1", since = "1.0.0")]
    #[derive(Clone)]
    pub struct Metadata(fs_imp::FileAttr);

    /// Iterator over the entries in a directory.
    ///
    /// This iterator is returned from the `read_dir` function of this module and
    /// will yield instances of `io::Result<DirEntry>`. Through a `DirEntry`
    /// information like the entry's path and possibly other metadata can be
    /// learned.
    ///
    /// # Errors
    ///
    /// This `io::Result` will be an `Err` if there's some sort of intermittent
    /// IO error during iteration.
    #[stable(feature = "rust1", since = "1.0.0")]
    pub struct ReadDir(fs_imp::ReadDir);

    /// Entries returned by the `ReadDir` iterator.
    ///
    /// An instance of `DirEntry` represents an entry inside of a directory on the
    /// filesystem. Each entry can be inspected via methods to learn about the full
    /// path or possibly other metadata through per-platform extension traits.
    #[stable(feature = "rust1", since = "1.0.0")]
    pub struct DirEntry(fs_imp::DirEntry);

    /// Options and flags which can be used to configure how a file is opened.
    ///
    /// This builder exposes the ability to configure how a `File` is opened and
    /// what operations are permitted on the open file. The `File::open` and
    /// `File::create` methods are aliases for commonly used options using this
    /// builder.
    ///
    /// Generally speaking, when using `OpenOptions`, you'll first call `new()`,
    /// then chain calls to methods to set each option, then call `open()`, passing
    /// the path of the file you're trying to open. This will give you a
    /// [`io::Result`][result] with a [`File`][file] inside that you can further
    /// operate on.
    ///
    /// [result]: ../io/type.Result.html
    /// [file]: struct.File.html
    ///
    /// # Examples
    ///
    /// Opening a file to read:
    ///
    /// ```no_run
    /// use std::fs::OpenOptions;
    ///
    /// let file = OpenOptions::new().read(true).open("foo.txt");
    /// ```
    ///
    /// Opening a file for both reading and writing, as well as creating it if it
    /// doesn't exist:
    ///
    /// ```no_run
    /// use std::fs::OpenOptions;
    ///
    /// let file = OpenOptions::new()
    ///             .read(true)
    ///             .write(true)
    ///             .create(true)
    ///             .open("foo.txt");
    /// ```
    #[derive(Clone)]
    #[stable(feature = "rust1", since = "1.0.0")]
    pub struct OpenOptions(fs_imp::OpenOptions);

    /// Representation of the various permissions on a file.
    ///
    /// This module only currently provides one bit of information, `readonly`,
    /// which is exposed on all currently supported platforms. Unix-specific
    /// functionality, such as mode bits, is available through the
    /// `os::unix::PermissionsExt` trait.
    #[derive(Clone, PartialEq, Eq, Debug)]
    #[stable(feature = "rust1", since = "1.0.0")]
    pub struct Permissions(fs_imp::FilePermissions);

    /// An structure representing a type of file with accessors for each file type.
    #[stable(feature = "file_type", since = "1.1.0")]
    #[derive(Copy, Clone, PartialEq, Eq, Hash)]
    pub struct FileType(fs_imp::FileType);

    /// A builder used to create directories in various manners.
    ///
    /// This builder also supports platform-specific options.
    #[stable(feature = "dir_builder", since = "1.6.0")]
    pub struct DirBuilder {
        inner: fs_imp::DirBuilder,
        recursive: bool,
    }

    impl File {
        /// Attempts to open a file in read-only mode.
        ///
        /// See the `OpenOptions::open` method for more details.
        ///
        /// # Errors
        ///
        /// This function will return an error if `path` does not already exist.
        /// Other errors may also be returned according to `OpenOptions::open`.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::File;
        ///
        /// # fn foo() -> std::io::Result<()> {
        /// let mut f = try!(File::open("foo.txt"));
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn open<P: AsRef<Path>>(path: P) -> io::Result<File> {
            OpenOptions::new().read(true).open(path.as_ref())
        }

        /// Opens a file in write-only mode.
        ///
        /// This function will create a file if it does not exist,
        /// and will truncate it if it does.
        ///
        /// See the `OpenOptions::open` function for more details.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::File;
        ///
        /// # fn foo() -> std::io::Result<()> {
        /// let mut f = try!(File::create("foo.txt"));
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn create<P: AsRef<Path>>(path: P) -> io::Result<File> {
            OpenOptions::new().write(true).create(true).truncate(true).open(path.as_ref())
        }

        /// Attempts to sync all OS-internal metadata to disk.
        ///
        /// This function will attempt to ensure that all in-core data reaches the
        /// filesystem before returning.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::File;
        /// use std::io::prelude::*;
        ///
        /// # fn foo() -> std::io::Result<()> {
        /// let mut f = try!(File::create("foo.txt"));
        /// try!(f.write_all(b"Hello, world!"));
        ///
        /// try!(f.sync_all());
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn sync_all(&self) -> io::Result<()> {
            self.inner.fsync()
        }

        /// This function is similar to `sync_all`, except that it may not
        /// synchronize file metadata to the filesystem.
        ///
        /// This is intended for use cases that must synchronize content, but don't
        /// need the metadata on disk. The goal of this method is to reduce disk
        /// operations.
        ///
        /// Note that some platforms may simply implement this in terms of
        /// `sync_all`.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::File;
        /// use std::io::prelude::*;
        ///
        /// # fn foo() -> std::io::Result<()> {
        /// let mut f = try!(File::create("foo.txt"));
        /// try!(f.write_all(b"Hello, world!"));
        ///
        /// try!(f.sync_data());
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn sync_data(&self) -> io::Result<()> {
            self.inner.datasync()
        }

        /// Truncates or extends the underlying file, updating the size of
        /// this file to become `size`.
        ///
        /// If the `size` is less than the current file's size, then the file will
        /// be shrunk. If it is greater than the current file's size, then the file
        /// will be extended to `size` and have all of the intermediate data filled
        /// in with 0s.
        ///
        /// # Errors
        ///
        /// This function will return an error if the file is not opened for writing.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::File;
        ///
        /// # fn foo() -> std::io::Result<()> {
        /// let mut f = try!(File::create("foo.txt"));
        /// try!(f.set_len(10));
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn set_len(&self, size: u64) -> io::Result<()> {
            self.inner.truncate(size)
        }

        /// Queries metadata about the underlying file.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::File;
        ///
        /// # fn foo() -> std::io::Result<()> {
        /// let mut f = try!(File::open("foo.txt"));
        /// let metadata = try!(f.metadata());
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn metadata(&self) -> io::Result<Metadata> {
            self.inner.file_attr().map(Metadata)
        }

        /// Creates a new independently owned handle to the underlying file.
        ///
        /// The returned `File` is a reference to the same state that this object
        /// references. Both handles will read and write with the same cursor
        /// position.
        #[stable(feature = "file_try_clone", since = "1.9.0")]
        pub fn try_clone(&self) -> io::Result<File> {
            Ok(File {
                inner: self.inner.duplicate()?
            })
        }
    }

    impl AsInner<fs_imp::File> for File {
        fn as_inner(&self) -> &fs_imp::File { &self.inner }
    }
    impl FromInner<fs_imp::File> for File {
        fn from_inner(f: fs_imp::File) -> File {
            File { inner: f }
        }
    }
    impl IntoInner<fs_imp::File> for File {
        fn into_inner(self) -> fs_imp::File {
            self.inner
        }
    }

    #[stable(feature = "rust1", since = "1.0.0")]
    impl fmt::Debug for File {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            self.inner.fmt(f)
        }
    }

    #[stable(feature = "rust1", since = "1.0.0")]
    impl Read for File {
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            self.inner.read(buf)
        }
        fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
            self.inner.read_to_end(buf)
        }
    }
    #[stable(feature = "rust1", since = "1.0.0")]
    impl Write for File {
        fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
            self.inner.write(buf)
        }
        fn flush(&mut self) -> io::Result<()> { self.inner.flush() }
    }
    #[stable(feature = "rust1", since = "1.0.0")]
    impl Seek for File {
        fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
            self.inner.seek(pos)
        }
    }
    #[stable(feature = "rust1", since = "1.0.0")]
    impl<'a> Read for &'a File {
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            self.inner.read(buf)
        }
        fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
            self.inner.read_to_end(buf)
        }
    }
    #[stable(feature = "rust1", since = "1.0.0")]
    impl<'a> Write for &'a File {
        fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
            self.inner.write(buf)
        }
        fn flush(&mut self) -> io::Result<()> { self.inner.flush() }
    }
    #[stable(feature = "rust1", since = "1.0.0")]
    impl<'a> Seek for &'a File {
        fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
            self.inner.seek(pos)
        }
    }

    impl OpenOptions {
        /// Creates a blank new set of options ready for configuration.
        ///
        /// All options are initially set to `false`.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::OpenOptions;
        ///
        /// let mut options = OpenOptions::new();
        /// let file = options.read(true).open("foo.txt");
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn new() -> OpenOptions {
            OpenOptions(fs_imp::OpenOptions::new())
        }

        /// Sets the option for read access.
        ///
        /// This option, when true, will indicate that the file should be
        /// `read`-able if opened.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::OpenOptions;
        ///
        /// let file = OpenOptions::new().read(true).open("foo.txt");
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn read(&mut self, read: bool) -> &mut OpenOptions {
            self.0.read(read); self
        }

        /// Sets the option for write access.
        ///
        /// This option, when true, will indicate that the file should be
        /// `write`-able if opened.
        ///
        /// If the file already exists, any write calls on it will overwrite its
        /// contents, without truncating it.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::OpenOptions;
        ///
        /// let file = OpenOptions::new().write(true).open("foo.txt");
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn write(&mut self, write: bool) -> &mut OpenOptions {
            self.0.write(write); self
        }

        /// Sets the option for the append mode.
        ///
        /// This option, when true, means that writes will append to a file instead
        /// of overwriting previous contents.
        /// Note that setting `.write(true).append(true)` has the same effect as
        /// setting only `.append(true)`.
        ///
        /// For most filesystems, the operating system guarantees that all writes are
        /// atomic: no writes get mangled because another process writes at the same
        /// time.
        ///
        /// One maybe obvious note when using append-mode: make sure that all data
        /// that belongs together is written to the file in one operation. This
        /// can be done by concatenating strings before passing them to `write()`,
        /// or using a buffered writer (with a buffer of adequate size),
        /// and calling `flush()` when the message is complete.
        ///
        /// If a file is opened with both read and append access, beware that after
        /// opening, and after every write, the position for reading may be set at the
        /// end of the file. So, before writing, save the current position (using
        /// `seek(SeekFrom::Current(0))`, and restore it before the next read.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::OpenOptions;
        ///
        /// let file = OpenOptions::new().append(true).open("foo.txt");
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn append(&mut self, append: bool) -> &mut OpenOptions {
            self.0.append(append); self
        }

        /// Sets the option for truncating a previous file.
        ///
        /// If a file is successfully opened with this option set it will truncate
        /// the file to 0 length if it already exists.
        ///
        /// The file must be opened with write access for truncate to work.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::OpenOptions;
        ///
        /// let file = OpenOptions::new().write(true).truncate(true).open("foo.txt");
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn truncate(&mut self, truncate: bool) -> &mut OpenOptions {
            self.0.truncate(truncate); self
        }

        /// Sets the option for creating a new file.
        ///
        /// This option indicates whether a new file will be created if the file
        /// does not yet already exist.
        ///
        /// In order for the file to be created, `write` or `append` access must
        /// be used.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::OpenOptions;
        ///
        /// let file = OpenOptions::new().write(true).create(true).open("foo.txt");
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn create(&mut self, create: bool) -> &mut OpenOptions {
            self.0.create(create); self
        }

        /// Sets the option to always create a new file.
        ///
        /// This option indicates whether a new file will be created.
        /// No file is allowed to exist at the target location, also no (dangling)
        /// symlink.
        ///
        /// This option is useful because it as atomic. Otherwise between checking
        /// whether a file exists and creating a new one, the file may have been
        /// created by another process (a TOCTOU race condition / attack).
        ///
        /// If `.create_new(true)` is set, `.create()` and `.truncate()` are
        /// ignored.
        ///
        /// The file must be opened with write or append access in order to create
        /// a new file.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::OpenOptions;
        ///
        /// let file = OpenOptions::new().write(true)
        ///                              .create_new(true)
        ///                              .open("foo.txt");
        /// ```
        #[stable(feature = "expand_open_options2", since = "1.9.0")]
        pub fn create_new(&mut self, create_new: bool) -> &mut OpenOptions {
            self.0.create_new(create_new); self
        }

        /// Opens a file at `path` with the options specified by `self`.
        ///
        /// # Errors
        ///
        /// This function will return an error under a number of different
        /// circumstances, to include but not limited to:
        ///
        /// * Opening a file that does not exist without setting `create` or
        ///   `create_new`.
        /// * Attempting to open a file with access that the user lacks
        ///   permissions for
        /// * Filesystem-level errors (full disk, etc)
        /// * Invalid combinations of open options (truncate without write access,
        ///   no access mode set, etc)
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::OpenOptions;
        ///
        /// let file = OpenOptions::new().open("foo.txt");
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn open<P: AsRef<Path>>(&self, path: P) -> io::Result<File> {
            self._open(path.as_ref())
        }

        fn _open(&self, path: &Path) -> io::Result<File> {
            let inner = fs_imp::File::open(path, &self.0)?;
            Ok(File { inner: inner })
        }
    }

    impl AsInnerMut<fs_imp::OpenOptions> for OpenOptions {
        fn as_inner_mut(&mut self) -> &mut fs_imp::OpenOptions { &mut self.0 }
    }

    impl Metadata {
        /// Returns the file type for this metadata.
        #[stable(feature = "file_type", since = "1.1.0")]
        pub fn file_type(&self) -> FileType {
            FileType(self.0.file_type())
        }

        /// Returns whether this metadata is for a directory.
        ///
        /// # Examples
        ///
        /// ```
        /// # fn foo() -> std::io::Result<()> {
        /// use std::fs;
        ///
        /// let metadata = try!(fs::metadata("foo.txt"));
        ///
        /// assert!(!metadata.is_dir());
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn is_dir(&self) -> bool { self.file_type().is_dir() }

        /// Returns whether this metadata is for a regular file.
        ///
        /// # Examples
        ///
        /// ```
        /// # fn foo() -> std::io::Result<()> {
        /// use std::fs;
        ///
        /// let metadata = try!(fs::metadata("foo.txt"));
        ///
        /// assert!(metadata.is_file());
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn is_file(&self) -> bool { self.file_type().is_file() }

        /// Returns the size of the file, in bytes, this metadata is for.
        ///
        /// # Examples
        ///
        /// ```
        /// # fn foo() -> std::io::Result<()> {
        /// use std::fs;
        ///
        /// let metadata = try!(fs::metadata("foo.txt"));
        ///
        /// assert_eq!(0, metadata.len());
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn len(&self) -> u64 { self.0.size() }

        /// Returns the permissions of the file this metadata is for.
        ///
        /// # Examples
        ///
        /// ```
        /// # fn foo() -> std::io::Result<()> {
        /// use std::fs;
        ///
        /// let metadata = try!(fs::metadata("foo.txt"));
        ///
        /// assert!(!metadata.permissions().readonly());
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn permissions(&self) -> Permissions {
            Permissions(self.0.perm())
        }

        /// Returns the last modification time listed in this metadata.
        ///
        /// The returned value corresponds to the `mtime` field of `stat` on Unix
        /// platforms and the `ftLastWriteTime` field on Windows platforms.
        ///
        /// # Errors
        ///
        /// This field may not be available on all platforms, and will return an
        /// `Err` on platforms where it is not available.
        #[unstable(feature = "fs_time", issue = "31399")]
        pub fn modified(&self) -> io::Result<SystemTime> {
            self.0.modified().map(FromInner::from_inner)
        }

        /// Returns the last access time of this metadata.
        ///
        /// The returned value corresponds to the `atime` field of `stat` on Unix
        /// platforms and the `ftLastAccessTime` field on Windows platforms.
        ///
        /// Note that not all platforms will keep this field update in a file's
        /// metadata, for example Windows has an option to disable updating this
        /// time when files are accessed and Linux similarly has `noatime`.
        ///
        /// # Errors
        ///
        /// This field may not be available on all platforms, and will return an
        /// `Err` on platforms where it is not available.
        #[unstable(feature = "fs_time", issue = "31399")]
        pub fn accessed(&self) -> io::Result<SystemTime> {
            self.0.accessed().map(FromInner::from_inner)
        }

        /// Returns the creation time listed in the this metadata.
        ///
        /// The returned value corresponds to the `birthtime` field of `stat` on
        /// Unix platforms and the `ftCreationTime` field on Windows platforms.
        ///
        /// # Errors
        ///
        /// This field may not be available on all platforms, and will return an
        /// `Err` on platforms where it is not available.
        #[unstable(feature = "fs_time", issue = "31399")]
        pub fn created(&self) -> io::Result<SystemTime> {
            self.0.created().map(FromInner::from_inner)
        }
    }

    impl AsInner<fs_imp::FileAttr> for Metadata {
        fn as_inner(&self) -> &fs_imp::FileAttr { &self.0 }
    }

    impl Permissions {
        /// Returns whether these permissions describe a readonly file.
        ///
        /// # Examples
        ///
        /// ```
        /// use std::fs::File;
        ///
        /// # fn foo() -> std::io::Result<()> {
        /// let mut f = try!(File::create("foo.txt"));
        /// let metadata = try!(f.metadata());
        ///
        /// assert_eq!(false, metadata.permissions().readonly());
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn readonly(&self) -> bool { self.0.readonly() }

        /// Modifies the readonly flag for this set of permissions.
        ///
        /// This operation does **not** modify the filesystem. To modify the
        /// filesystem use the `fs::set_permissions` function.
        ///
        /// # Examples
        ///
        /// ```
        /// use std::fs::File;
        ///
        /// # fn foo() -> std::io::Result<()> {
        /// let f = try!(File::create("foo.txt"));
        /// let metadata = try!(f.metadata());
        /// let mut permissions = metadata.permissions();
        ///
        /// permissions.set_readonly(true);
        ///
        /// // filesystem doesn't change
        /// assert_eq!(false, metadata.permissions().readonly());
        ///
        /// // just this particular `permissions`.
        /// assert_eq!(true, permissions.readonly());
        /// # Ok(())
        /// # }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn set_readonly(&mut self, readonly: bool) {
            self.0.set_readonly(readonly)
        }
    }

    impl FileType {
        /// Test whether this file type represents a directory.
        #[stable(feature = "file_type", since = "1.1.0")]
        pub fn is_dir(&self) -> bool { self.0.is_dir() }

        /// Test whether this file type represents a regular file.
        #[stable(feature = "file_type", since = "1.1.0")]
        pub fn is_file(&self) -> bool { self.0.is_file() }

        /// Test whether this file type represents a symbolic link.
        #[stable(feature = "file_type", since = "1.1.0")]
        pub fn is_symlink(&self) -> bool { self.0.is_symlink() }
    }

    impl AsInner<fs_imp::FileType> for FileType {
        fn as_inner(&self) -> &fs_imp::FileType { &self.0 }
    }

    impl FromInner<fs_imp::FilePermissions> for Permissions {
        fn from_inner(f: fs_imp::FilePermissions) -> Permissions {
            Permissions(f)
        }
    }

    impl AsInner<fs_imp::FilePermissions> for Permissions {
        fn as_inner(&self) -> &fs_imp::FilePermissions { &self.0 }
    }

    #[stable(feature = "rust1", since = "1.0.0")]
    impl Iterator for ReadDir {
        type Item = io::Result<DirEntry>;

        fn next(&mut self) -> Option<io::Result<DirEntry>> {
            self.0.next().map(|entry| entry.map(DirEntry))
        }
    }

    impl DirEntry {
        /// Returns the full path to the file that this entry represents.
        ///
        /// The full path is created by joining the original path to `read_dir` or
        /// `walk_dir` with the filename of this entry.
        ///
        /// # Examples
        ///
        /// ```
        /// use std::fs;
        /// # fn foo() -> std::io::Result<()> {
        /// for entry in try!(fs::read_dir(".")) {
        ///     let dir = try!(entry);
        ///     println!("{:?}", dir.path());
        /// }
        /// # Ok(())
        /// # }
        /// ```
        ///
        /// This prints output like:
        ///
        /// ```text
        /// "./whatever.txt"
        /// "./foo.html"
        /// "./hello_world.rs"
        /// ```
        ///
        /// The exact text, of course, depends on what files you have in `.`.
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn path(&self) -> PathBuf { self.0.path() }

        /// Return the metadata for the file that this entry points at.
        ///
        /// This function will not traverse symlinks if this entry points at a
        /// symlink.
        ///
        /// # Platform-specific behavior
        ///
        /// On Windows this function is cheap to call (no extra system calls
        /// needed), but on Unix platforms this function is the equivalent of
        /// calling `symlink_metadata` on the path.
        #[stable(feature = "dir_entry_ext", since = "1.1.0")]
        pub fn metadata(&self) -> io::Result<Metadata> {
            self.0.metadata().map(Metadata)
        }

        /// Return the file type for the file that this entry points at.
        ///
        /// This function will not traverse symlinks if this entry points at a
        /// symlink.
        ///
        /// # Platform-specific behavior
        ///
        /// On Windows and most Unix platforms this function is free (no extra
        /// system calls needed), but some Unix platforms may require the equivalent
        /// call to `symlink_metadata` to learn about the target file type.
        #[stable(feature = "dir_entry_ext", since = "1.1.0")]
        pub fn file_type(&self) -> io::Result<FileType> {
            self.0.file_type().map(FileType)
        }

        /// Returns the bare file name of this directory entry without any other
        /// leading path component.
        #[stable(feature = "dir_entry_ext", since = "1.1.0")]
        pub fn file_name(&self) -> OsString {
            self.0.file_name()
        }
    }

    impl AsInner<fs_imp::DirEntry> for DirEntry {
        fn as_inner(&self) -> &fs_imp::DirEntry { &self.0 }
    }

    /// Removes a file from the filesystem.
    ///
    /// Note that there is no
    /// guarantee that the file is immediately deleted (e.g. depending on
    /// platform, other open file descriptors may prevent immediate removal).
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `unlink` function on Unix
    /// and the `DeleteFile` function on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * `path` points to a directory.
    /// * The user lacks permissions to remove the file.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// try!(fs::remove_file("a.txt"));
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn remove_file<P: AsRef<Path>>(path: P) -> io::Result<()> {
        fs_imp::unlink(path.as_ref())
    }

    /// Given a path, query the file system to get information about a file,
    /// directory, etc.
    ///
    /// This function will traverse symbolic links to query information about the
    /// destination file.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `stat` function on Unix
    /// and the `GetFileAttributesEx` function on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * The user lacks permissions to perform `metadata` call on `path`.
    /// * `path` does not exist.
    ///
    /// # Examples
    ///
    /// ```rust
    /// # fn foo() -> std::io::Result<()> {
    /// use std::fs;
    ///
    /// let attr = try!(fs::metadata("/some/file/path.txt"));
    /// // inspect attr ...
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
        fs_imp::stat(path.as_ref()).map(Metadata)
    }

    /// Query the metadata about a file without following symlinks.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `lstat` function on Unix
    /// and the `GetFileAttributesEx` function on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * The user lacks permissions to perform `metadata` call on `path`.
    /// * `path` does not exist.
    ///
    /// # Examples
    ///
    /// ```rust
    /// # fn foo() -> std::io::Result<()> {
    /// use std::fs;
    ///
    /// let attr = try!(fs::symlink_metadata("/some/file/path.txt"));
    /// // inspect attr ...
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "symlink_metadata", since = "1.1.0")]
    pub fn symlink_metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
        fs_imp::lstat(path.as_ref()).map(Metadata)
    }

    /// Rename a file or directory to a new name, replacing the original file if
    /// `to` already exists.
    ///
    /// This will not work if the new name is on a different mount point.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `rename` function on Unix
    /// and the `MoveFileEx` function with the `MOVEFILE_REPLACE_EXISTING` flag on Windows.
    ///
    /// Because of this, the behavior when both `from` and `to` exist differs. On
    /// Unix, if `from` is a directory, `to` must also be an (empty) directory. If
    /// `from` is not a directory, `to` must also be not a directory. In contrast,
    /// on Windows, `from` can be anything, but `to` must *not* be a directory.
    ///
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * `from` does not exist.
    /// * The user lacks permissions to view contents.
    /// * `from` and `to` are on separate filesystems.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// try!(fs::rename("a.txt", "b.txt")); // Rename a.txt to b.txt
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn rename<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()> {
        fs_imp::rename(from.as_ref(), to.as_ref())
    }

    /// Copies the contents of one file to another. This function will also
    /// copy the permission bits of the original file to the destination file.
    ///
    /// This function will **overwrite** the contents of `to`.
    ///
    /// Note that if `from` and `to` both point to the same file, then the file
    /// will likely get truncated by this operation.
    ///
    /// On success, the total number of bytes copied is returned.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `open` function in Unix
    /// with `O_RDONLY` for `from` and `O_WRONLY`, `O_CREAT`, and `O_TRUNC` for `to`.
    /// `O_CLOEXEC` is set for returned file descriptors.
    /// On Windows, this function currently corresponds to `CopyFileEx`.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * The `from` path is not a file.
    /// * The `from` file does not exist.
    /// * The current process does not have the permission rights to access
    ///   `from` or write `to`.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// try!(fs::copy("foo.txt", "bar.txt"));  // Copy foo.txt to bar.txt
    /// # Ok(()) }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<u64> {
        fs_imp::copy(from.as_ref(), to.as_ref())
    }

    /// Creates a new hard link on the filesystem.
    ///
    /// The `dst` path will be a link pointing to the `src` path. Note that systems
    /// often require these two paths to both be located on the same filesystem.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `link` function on Unix
    /// and the `CreateHardLink` function on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * The `src` path is not a file or doesn't exist.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// try!(fs::hard_link("a.txt", "b.txt")); // Hard link a.txt to b.txt
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn hard_link<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<()> {
        fs_imp::link(src.as_ref(), dst.as_ref())
    }

    /// Creates a new symbolic link on the filesystem.
    ///
    /// The `dst` path will be a symbolic link pointing to the `src` path.
    /// On Windows, this will be a file symlink, not a directory symlink;
    /// for this reason, the platform-specific `std::os::unix::fs::symlink`
    /// and `std::os::windows::fs::{symlink_file, symlink_dir}` should be
    /// used instead to make the intent explicit.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// try!(fs::soft_link("a.txt", "b.txt"));
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[rustc_deprecated(since = "1.1.0",
                 reason = "replaced with std::os::unix::fs::symlink and \
                           std::os::windows::fs::{symlink_file, symlink_dir}")]
    pub fn soft_link<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<()> {
        fs_imp::symlink(src.as_ref(), dst.as_ref())
    }

    /// Reads a symbolic link, returning the file that the link points to.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `readlink` function on Unix
    /// and the `CreateFile` function with `FILE_FLAG_OPEN_REPARSE_POINT` and
    /// `FILE_FLAG_BACKUP_SEMANTICS` flags on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * `path` is not a symbolic link.
    /// * `path` does not exist.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// let path = try!(fs::read_link("a.txt"));
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn read_link<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
        fs_imp::readlink(path.as_ref())
    }

    /// Returns the canonical form of a path with all intermediate components
    /// normalized and symbolic links resolved.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `realpath` function on Unix
    /// and the `CreateFile` and `GetFinalPathNameByHandle` functions on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * `path` does not exist.
    /// * A component in path is not a directory.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// let path = try!(fs::canonicalize("../a/../foo.txt"));
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "fs_canonicalize", since = "1.5.0")]
    pub fn canonicalize<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
        fs_imp::canonicalize(path.as_ref())
    }

    /// Creates a new, empty directory at the provided path
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `mkdir` function on Unix
    /// and the `CreateDirectory` function on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * User lacks permissions to create directory at `path`.
    /// * `path` already exists.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// try!(fs::create_dir("/some/dir"));
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn create_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
        DirBuilder::new().create(path.as_ref())
    }

    /// Recursively create a directory and all of its parent components if they
    /// are missing.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `mkdir` function on Unix
    /// and the `CreateDirectory` function on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * If any directory in the path specified by `path`
    /// does not already exist and it could not be created otherwise. The specific
    /// error conditions for when a directory is being created (after it is
    /// determined to not exist) are outlined by `fs::create_dir`.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// try!(fs::create_dir_all("/some/dir"));
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn create_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
        DirBuilder::new().recursive(true).create(path.as_ref())
    }

    /// Removes an existing, empty directory.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `rmdir` function on Unix
    /// and the `RemoveDirectory` function on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * The user lacks permissions to remove the directory at the provided `path`.
    /// * The directory isn't empty.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// try!(fs::remove_dir("/some/dir"));
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
        fs_imp::rmdir(path.as_ref())
    }

    /// Removes a directory at this path, after removing all its contents. Use
    /// carefully!
    ///
    /// This function does **not** follow symbolic links and it will simply remove the
    /// symbolic link itself.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to `opendir`, `lstat`, `rm` and `rmdir` functions on Unix
    /// and the `FindFirstFile`, `GetFileAttributesEx`, `DeleteFile`, and `RemoveDirectory` functions
    /// on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// See `file::remove_file` and `fs::remove_dir`.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::fs;
    ///
    /// # fn foo() -> std::io::Result<()> {
    /// try!(fs::remove_dir_all("/some/dir"));
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
        fs_imp::remove_dir_all(path.as_ref())
    }

    /// Returns an iterator over the entries within a directory.
    ///
    /// The iterator will yield instances of `io::Result<DirEntry>`. New errors may
    /// be encountered after an iterator is initially constructed.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `opendir` function on Unix
    /// and the `FindFirstFile` function on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * The provided `path` doesn't exist.
    /// * The process lacks permissions to view the contents.
    /// * The `path` points at a non-directory file.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::io;
    /// use std::fs::{self, DirEntry};
    /// use std::path::Path;
    ///
    /// // one possible implementation of walking a directory only visiting files
    /// fn visit_dirs(dir: &Path, cb: &Fn(&DirEntry)) -> io::Result<()> {
    ///     if try!(fs::metadata(dir)).is_dir() {
    ///         for entry in try!(fs::read_dir(dir)) {
    ///             let entry = try!(entry);
    ///             if try!(fs::metadata(entry.path())).is_dir() {
    ///                 try!(visit_dirs(&entry.path(), cb));
    ///             } else {
    ///                 cb(&entry);
    ///             }
    ///         }
    ///     }
    ///     Ok(())
    /// }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn read_dir<P: AsRef<Path>>(path: P) -> io::Result<ReadDir> {
        fs_imp::readdir(path.as_ref()).map(ReadDir)
    }

    /// Changes the permissions found on a file or a directory.
    ///
    /// # Platform-specific behavior
    ///
    /// This function currently corresponds to the `chmod` function on Unix
    /// and the `SetFileAttributes` function on Windows.
    /// Note that, this [may change in the future][changes].
    /// [changes]: ../io/index.html#platform-specific-behavior
    ///
    /// # Errors
    ///
    /// This function will return an error in the following situations, but is not
    /// limited to just these cases:
    ///
    /// * `path` does not exist.
    /// * The user lacks the permission to change attributes of the file.
    ///
    /// # Examples
    ///
    /// ```
    /// # fn foo() -> std::io::Result<()> {
    /// use std::fs;
    ///
    /// let mut perms = try!(fs::metadata("foo.txt")).permissions();
    /// perms.set_readonly(true);
    /// try!(fs::set_permissions("foo.txt", perms));
    /// # Ok(())
    /// # }
    /// ```
    #[stable(feature = "set_permissions", since = "1.1.0")]
    pub fn set_permissions<P: AsRef<Path>>(path: P, perm: Permissions)
                                           -> io::Result<()> {
        fs_imp::set_perm(path.as_ref(), perm.0)
    }

    impl DirBuilder {
        /// Creates a new set of options with default mode/security settings for all
        /// platforms and also non-recursive.
        #[stable(feature = "dir_builder", since = "1.6.0")]
        pub fn new() -> DirBuilder {
            DirBuilder {
                inner: fs_imp::DirBuilder::new(),
                recursive: false,
            }
        }

        /// Indicate that directories create should be created recursively, creating
        /// all parent directories if they do not exist with the same security and
        /// permissions settings.
        ///
        /// This option defaults to `false`
        #[stable(feature = "dir_builder", since = "1.6.0")]
        pub fn recursive(&mut self, recursive: bool) -> &mut Self {
            self.recursive = recursive;
            self
        }

        /// Create the specified directory with the options configured in this
        /// builder.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use std::fs::{self, DirBuilder};
        ///
        /// let path = "/tmp/foo/bar/baz";
        /// DirBuilder::new()
        ///     .recursive(true)
        ///     .create(path).unwrap();
        ///
        /// assert!(fs::metadata(path).unwrap().is_dir());
        /// ```
        #[stable(feature = "dir_builder", since = "1.6.0")]
        pub fn create<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
            self._create(path.as_ref())
        }

        fn _create(&self, path: &Path) -> io::Result<()> {
            if self.recursive {
                self.create_dir_all(path)
            } else {
                self.inner.mkdir(path)
            }
        }

        fn create_dir_all(&self, path: &Path) -> io::Result<()> {
            if path == Path::new("") || path.is_dir() { return Ok(()) }
            if let Some(p) = path.parent() {
                self.create_dir_all(p)?
            }
            self.inner.mkdir(path)
        }
    }

    impl AsInnerMut<fs_imp::DirBuilder> for DirBuilder {
        fn as_inner_mut(&mut self) -> &mut fs_imp::DirBuilder {
            &mut self.inner
        }
    }

    #[cfg(test)]
    mod tests {
        use prelude::v1::*;
        use io::prelude::*;

        use fs::{self, File, OpenOptions};
        use io::{ErrorKind, SeekFrom};
        use path::Path;
        use rand::{StdRng, Rng};
        use str;
        use sys_common::io::test::{TempDir, tmpdir};

        #[cfg(windows)]
        use os::windows::fs::{symlink_dir, symlink_file};
        #[cfg(windows)]
        use sys::fs::symlink_junction;
        #[cfg(unix)]
        use os::unix::fs::symlink as symlink_dir;
        #[cfg(unix)]
        use os::unix::fs::symlink as symlink_file;
        #[cfg(unix)]
        use os::unix::fs::symlink as symlink_junction;

        macro_rules! check { ($e:expr) => (
            match $e {
                Ok(t) => t,
                Err(e) => panic!("{} failed with: {}", stringify!($e), e),
            }
        ) }

        macro_rules! error { ($e:expr, $s:expr) => (
            match $e {
                Ok(_) => panic!("Unexpected success. Should've been: {:?}", $s),
                Err(ref err) => assert!(err.to_string().contains($s),
                                        format!("`{}` did not contain `{}`", err, $s))
            }
        ) }

        // Several test fail on windows if the user does not have permission to
        // create symlinks (the `SeCreateSymbolicLinkPrivilege`). Instead of
        // disabling these test on Windows, use this function to test whether we
        // have permission, and return otherwise. This way, we still don't run these
        // tests most of the time, but at least we do if the user has the right
        // permissions.
        pub fn got_symlink_permission(tmpdir: &TempDir) -> bool {
            if cfg!(unix) { return true }
            let link = tmpdir.join("some_hopefully_unique_link_name");

            match symlink_file(r"nonexisting_target", link) {
                Ok(_) => true,
                Err(ref err) =>
                    if err.to_string().contains("A required privilege is not held by the client.") {
                        false
                    } else {
                        true
                    }
            }
        }

        #[test]
        fn file_test_io_smoke_test() {
            let message = "it's alright. have a good time";
            let tmpdir = tmpdir();
            let filename = &tmpdir.join("file_rt_io_file_test.txt");
            {
                let mut write_stream = check!(File::create(filename));
                check!(write_stream.write(message.as_bytes()));
            }
            {
                let mut read_stream = check!(File::open(filename));
                let mut read_buf = [0; 1028];
                let read_str = match check!(read_stream.read(&mut read_buf)) {
                    0 => panic!("shouldn't happen"),
                    n => str::from_utf8(&read_buf[..n]).unwrap().to_string()
                };
                assert_eq!(read_str, message);
            }
            check!(fs::remove_file(filename));
        }

        #[test]
        fn invalid_path_raises() {
            let tmpdir = tmpdir();
            let filename = &tmpdir.join("file_that_does_not_exist.txt");
            let result = File::open(filename);

            if cfg!(unix) {
                error!(result, "No such file or directory");
            }
            if cfg!(windows) {
                error!(result, "The system cannot find the file specified");
            }
        }

        #[test]
        fn file_test_iounlinking_invalid_path_should_raise_condition() {
            let tmpdir = tmpdir();
            let filename = &tmpdir.join("file_another_file_that_does_not_exist.txt");

            let result = fs::remove_file(filename);

            if cfg!(unix) {
                error!(result, "No such file or directory");
            }
            if cfg!(windows) {
                error!(result, "The system cannot find the file specified");
            }
        }

        #[test]
        fn file_test_io_non_positional_read() {
            let message: &str = "ten-four";
            let mut read_mem = [0; 8];
            let tmpdir = tmpdir();
            let filename = &tmpdir.join("file_rt_io_file_test_positional.txt");
            {
                let mut rw_stream = check!(File::create(filename));
                check!(rw_stream.write(message.as_bytes()));
            }
            {
                let mut read_stream = check!(File::open(filename));
                {
                    let read_buf = &mut read_mem[0..4];
                    check!(read_stream.read(read_buf));
                }
                {
                    let read_buf = &mut read_mem[4..8];
                    check!(read_stream.read(read_buf));
                }
            }
            check!(fs::remove_file(filename));
            let read_str = str::from_utf8(&read_mem).unwrap();
            assert_eq!(read_str, message);
        }

        #[test]
        fn file_test_io_seek_and_tell_smoke_test() {
            let message = "ten-four";
            let mut read_mem = [0; 4];
            let set_cursor = 4 as u64;
            let tell_pos_pre_read;
            let tell_pos_post_read;
            let tmpdir = tmpdir();
            let filename = &tmpdir.join("file_rt_io_file_test_seeking.txt");
            {
                let mut rw_stream = check!(File::create(filename));
                check!(rw_stream.write(message.as_bytes()));
            }
            {
                let mut read_stream = check!(File::open(filename));
                check!(read_stream.seek(SeekFrom::Start(set_cursor)));
                tell_pos_pre_read = check!(read_stream.seek(SeekFrom::Current(0)));
                check!(read_stream.read(&mut read_mem));
                tell_pos_post_read = check!(read_stream.seek(SeekFrom::Current(0)));
            }
            check!(fs::remove_file(filename));
            let read_str = str::from_utf8(&read_mem).unwrap();
            assert_eq!(read_str, &message[4..8]);
            assert_eq!(tell_pos_pre_read, set_cursor);
            assert_eq!(tell_pos_post_read, message.len() as u64);
        }

        #[test]
        fn file_test_io_seek_and_write() {
            let initial_msg =   "food-is-yummy";
            let overwrite_msg =    "-the-bar!!";
            let final_msg =     "foo-the-bar!!";
            let seek_idx = 3;
            let mut read_mem = [0; 13];
            let tmpdir = tmpdir();
            let filename = &tmpdir.join("file_rt_io_file_test_seek_and_write.txt");
            {
                let mut rw_stream = check!(File::create(filename));
                check!(rw_stream.write(initial_msg.as_bytes()));
                check!(rw_stream.seek(SeekFrom::Start(seek_idx)));
                check!(rw_stream.write(overwrite_msg.as_bytes()));
            }
            {
                let mut read_stream = check!(File::open(filename));
                check!(read_stream.read(&mut read_mem));
            }
            check!(fs::remove_file(filename));
            let read_str = str::from_utf8(&read_mem).unwrap();
            assert!(read_str == final_msg);
        }

        #[test]
        fn file_test_io_seek_shakedown() {
            //                   01234567890123
            let initial_msg =   "qwer-asdf-zxcv";
            let chunk_one: &str = "qwer";
            let chunk_two: &str = "asdf";
            let chunk_three: &str = "zxcv";
            let mut read_mem = [0; 4];
            let tmpdir = tmpdir();
            let filename = &tmpdir.join("file_rt_io_file_test_seek_shakedown.txt");
            {
                let mut rw_stream = check!(File::create(filename));
                check!(rw_stream.write(initial_msg.as_bytes()));
            }
            {
                let mut read_stream = check!(File::open(filename));

                check!(read_stream.seek(SeekFrom::End(-4)));
                check!(read_stream.read(&mut read_mem));
                assert_eq!(str::from_utf8(&read_mem).unwrap(), chunk_three);

                check!(read_stream.seek(SeekFrom::Current(-9)));
                check!(read_stream.read(&mut read_mem));
                assert_eq!(str::from_utf8(&read_mem).unwrap(), chunk_two);

                check!(read_stream.seek(SeekFrom::Start(0)));
                check!(read_stream.read(&mut read_mem));
                assert_eq!(str::from_utf8(&read_mem).unwrap(), chunk_one);
            }
            check!(fs::remove_file(filename));
        }

        #[test]
        fn file_test_stat_is_correct_on_is_file() {
            let tmpdir = tmpdir();
            let filename = &tmpdir.join("file_stat_correct_on_is_file.txt");
            {
                let mut opts = OpenOptions::new();
                let mut fs = check!(opts.read(true).write(true)
                                        .create(true).open(filename));
                let msg = "hw";
                fs.write(msg.as_bytes()).unwrap();

                let fstat_res = check!(fs.metadata());
                assert!(fstat_res.is_file());
            }
            let stat_res_fn = check!(fs::metadata(filename));
            assert!(stat_res_fn.is_file());
            let stat_res_meth = check!(filename.metadata());
            assert!(stat_res_meth.is_file());
            check!(fs::remove_file(filename));
        }

        #[test]
        fn file_test_stat_is_correct_on_is_dir() {
            let tmpdir = tmpdir();
            let filename = &tmpdir.join("file_stat_correct_on_is_dir");
            check!(fs::create_dir(filename));
            let stat_res_fn = check!(fs::metadata(filename));
            assert!(stat_res_fn.is_dir());
            let stat_res_meth = check!(filename.metadata());
            assert!(stat_res_meth.is_dir());
            check!(fs::remove_dir(filename));
        }

        #[test]
        fn file_test_fileinfo_false_when_checking_is_file_on_a_directory() {
            let tmpdir = tmpdir();
            let dir = &tmpdir.join("fileinfo_false_on_dir");
            check!(fs::create_dir(dir));
            assert!(!dir.is_file());
            check!(fs::remove_dir(dir));
        }

        #[test]
        fn file_test_fileinfo_check_exists_before_and_after_file_creation() {
            let tmpdir = tmpdir();
            let file = &tmpdir.join("fileinfo_check_exists_b_and_a.txt");
            check!(check!(File::create(file)).write(b"foo"));
            assert!(file.exists());
            check!(fs::remove_file(file));
            assert!(!file.exists());
        }

        #[test]
        fn file_test_directoryinfo_check_exists_before_and_after_mkdir() {
            let tmpdir = tmpdir();
            let dir = &tmpdir.join("before_and_after_dir");
            assert!(!dir.exists());
            check!(fs::create_dir(dir));
            assert!(dir.exists());
            assert!(dir.is_dir());
            check!(fs::remove_dir(dir));
            assert!(!dir.exists());
        }

        #[test]
        fn file_test_directoryinfo_readdir() {
            let tmpdir = tmpdir();
            let dir = &tmpdir.join("di_readdir");
            check!(fs::create_dir(dir));
            let prefix = "foo";
            for n in 0..3 {
                let f = dir.join(&format!("{}.txt", n));
                let mut w = check!(File::create(&f));
                let msg_str = format!("{}{}", prefix, n.to_string());
                let msg = msg_str.as_bytes();
                check!(w.write(msg));
            }
            let files = check!(fs::read_dir(dir));
            let mut mem = [0; 4];
            for f in files {
                let f = f.unwrap().path();
                {
                    let n = f.file_stem().unwrap();
                    check!(check!(File::open(&f)).read(&mut mem));
                    let read_str = str::from_utf8(&mem).unwrap();
                    let expected = format!("{}{}", prefix, n.to_str().unwrap());
                    assert_eq!(expected, read_str);
                }
                check!(fs::remove_file(&f));
            }
            check!(fs::remove_dir(dir));
        }

        #[test]
        fn mkdir_path_already_exists_error() {
            let tmpdir = tmpdir();
            let dir = &tmpdir.join("mkdir_error_twice");
            check!(fs::create_dir(dir));
            let e = fs::create_dir(dir).unwrap_err();
            assert_eq!(e.kind(), ErrorKind::AlreadyExists);
        }

        #[test]
        fn recursive_mkdir() {
            let tmpdir = tmpdir();
            let dir = tmpdir.join("d1/d2");
            check!(fs::create_dir_all(&dir));
            assert!(dir.is_dir())
        }

        #[test]
        fn recursive_mkdir_failure() {
            let tmpdir = tmpdir();
            let dir = tmpdir.join("d1");
            let file = dir.join("f1");

            check!(fs::create_dir_all(&dir));
            check!(File::create(&file));

            let result = fs::create_dir_all(&file);

            assert!(result.is_err());
        }

        #[test]
        fn recursive_mkdir_slash() {
            check!(fs::create_dir_all(&Path::new("/")));
        }

        #[test]
        fn recursive_rmdir() {
            let tmpdir = tmpdir();
            let d1 = tmpdir.join("d1");
            let dt = d1.join("t");
            let dtt = dt.join("t");
            let d2 = tmpdir.join("d2");
            let canary = d2.join("do_not_delete");
            check!(fs::create_dir_all(&dtt));
            check!(fs::create_dir_all(&d2));
            check!(check!(File::create(&canary)).write(b"foo"));
            check!(symlink_junction(&d2, &dt.join("d2")));
            let _ = symlink_file(&canary, &d1.join("canary"));
            check!(fs::remove_dir_all(&d1));

            assert!(!d1.is_dir());
            assert!(canary.exists());
        }

        #[test]
        fn recursive_rmdir_of_symlink() {
            // test we do not recursively delete a symlink but only dirs.
            let tmpdir = tmpdir();
            let link = tmpdir.join("d1");
            let dir = tmpdir.join("d2");
            let canary = dir.join("do_not_delete");
            check!(fs::create_dir_all(&dir));
            check!(check!(File::create(&canary)).write(b"foo"));
            check!(symlink_junction(&dir, &link));
            check!(fs::remove_dir_all(&link));

            assert!(!link.is_dir());
            assert!(canary.exists());
        }

        #[test]
        // only Windows makes a distinction between file and directory symlinks.
        #[cfg(windows)]
        fn recursive_rmdir_of_file_symlink() {
            let tmpdir = tmpdir();
            if !got_symlink_permission(&tmpdir) { return };

            let f1 = tmpdir.join("f1");
            let f2 = tmpdir.join("f2");
            check!(check!(File::create(&f1)).write(b"foo"));
            check!(symlink_file(&f1, &f2));
            match fs::remove_dir_all(&f2) {
                Ok(..) => panic!("wanted a failure"),
                Err(..) => {}
            }
        }

        #[test]
        fn unicode_path_is_dir() {
            assert!(Path::new(".").is_dir());
            assert!(!Path::new("test/stdtest/fs.rs").is_dir());

            let tmpdir = tmpdir();

            let mut dirpath = tmpdir.path().to_path_buf();
            dirpath.push("test-가一ー你好");
            check!(fs::create_dir(&dirpath));
            assert!(dirpath.is_dir());

            let mut filepath = dirpath;
            filepath.push("unicode-file-\u{ac00}\u{4e00}\u{30fc}\u{4f60}\u{597d}.rs");
            check!(File::create(&filepath)); // ignore return; touch only
            assert!(!filepath.is_dir());
            assert!(filepath.exists());
        }

        #[test]
        fn unicode_path_exists() {
            assert!(Path::new(".").exists());
            assert!(!Path::new("test/nonexistent-bogus-path").exists());

            let tmpdir = tmpdir();
            let unicode = tmpdir.path();
            let unicode = unicode.join(&format!("test-각丁ー再见"));
            check!(fs::create_dir(&unicode));
            assert!(unicode.exists());
            assert!(!Path::new("test/unicode-bogus-path-각丁ー再见").exists());
        }

        #[test]
        fn copy_file_does_not_exist() {
            let from = Path::new("test/nonexistent-bogus-path");
            let to = Path::new("test/other-bogus-path");

            match fs::copy(&from, &to) {
                Ok(..) => panic!(),
                Err(..) => {
                    assert!(!from.exists());
                    assert!(!to.exists());
                }
            }
        }

        #[test]
        fn copy_src_does_not_exist() {
            let tmpdir = tmpdir();
            let from = Path::new("test/nonexistent-bogus-path");
            let to = tmpdir.join("out.txt");
            check!(check!(File::create(&to)).write(b"hello"));
            assert!(fs::copy(&from, &to).is_err());
            assert!(!from.exists());
            let mut v = Vec::new();
            check!(check!(File::open(&to)).read_to_end(&mut v));
            assert_eq!(v, b"hello");
        }

        #[test]
        fn copy_file_ok() {
            let tmpdir = tmpdir();
            let input = tmpdir.join("in.txt");
            let out = tmpdir.join("out.txt");

            check!(check!(File::create(&input)).write(b"hello"));
            check!(fs::copy(&input, &out));
            let mut v = Vec::new();
            check!(check!(File::open(&out)).read_to_end(&mut v));
            assert_eq!(v, b"hello");

            assert_eq!(check!(input.metadata()).permissions(),
                       check!(out.metadata()).permissions());
        }

        #[test]
        fn copy_file_dst_dir() {
            let tmpdir = tmpdir();
            let out = tmpdir.join("out");

            check!(File::create(&out));
            match fs::copy(&*out, tmpdir.path()) {
                Ok(..) => panic!(), Err(..) => {}
            }
        }

        #[test]
        fn copy_file_dst_exists() {
            let tmpdir = tmpdir();
            let input = tmpdir.join("in");
            let output = tmpdir.join("out");

            check!(check!(File::create(&input)).write("foo".as_bytes()));
            check!(check!(File::create(&output)).write("bar".as_bytes()));
            check!(fs::copy(&input, &output));

            let mut v = Vec::new();
            check!(check!(File::open(&output)).read_to_end(&mut v));
            assert_eq!(v, b"foo".to_vec());
        }

        #[test]
        fn copy_file_src_dir() {
            let tmpdir = tmpdir();
            let out = tmpdir.join("out");

            match fs::copy(tmpdir.path(), &out) {
                Ok(..) => panic!(), Err(..) => {}
            }
            assert!(!out.exists());
        }

        #[test]
        fn copy_file_preserves_perm_bits() {
            let tmpdir = tmpdir();
            let input = tmpdir.join("in.txt");
            let out = tmpdir.join("out.txt");

            let attr = check!(check!(File::create(&input)).metadata());
            let mut p = attr.permissions();
            p.set_readonly(true);
            check!(fs::set_permissions(&input, p));
            check!(fs::copy(&input, &out));
            assert!(check!(out.metadata()).permissions().readonly());
            check!(fs::set_permissions(&input, attr.permissions()));
            check!(fs::set_permissions(&out, attr.permissions()));
        }

        #[cfg(windows)]
        #[test]
        fn copy_file_preserves_streams() {
            let tmp = tmpdir();
            check!(check!(File::create(tmp.join("in.txt:bunny"))).write("carrot".as_bytes()));
            assert_eq!(check!(fs::copy(tmp.join("in.txt"), tmp.join("out.txt"))), 6);
            assert_eq!(check!(tmp.join("out.txt").metadata()).len(), 0);
            let mut v = Vec::new();
            check!(check!(File::open(tmp.join("out.txt:bunny"))).read_to_end(&mut v));
            assert_eq!(v, b"carrot".to_vec());
        }

        #[test]
        fn symlinks_work() {
            let tmpdir = tmpdir();
            if !got_symlink_permission(&tmpdir) { return };

            let input = tmpdir.join("in.txt");
            let out = tmpdir.join("out.txt");

            check!(check!(File::create(&input)).write("foobar".as_bytes()));
            check!(symlink_file(&input, &out));
            assert!(check!(out.symlink_metadata()).file_type().is_symlink());
            assert_eq!(check!(fs::metadata(&out)).len(),
                       check!(fs::metadata(&input)).len());
            let mut v = Vec::new();
            check!(check!(File::open(&out)).read_to_end(&mut v));
            assert_eq!(v, b"foobar".to_vec());
        }

        #[test]
        fn symlink_noexist() {
            // Symlinks can point to things that don't exist
            let tmpdir = tmpdir();
            if !got_symlink_permission(&tmpdir) { return };

            // Use a relative path for testing. Symlinks get normalized by Windows,
            // so we may not get the same path back for absolute paths
            check!(symlink_file(&"foo", &tmpdir.join("bar")));
            assert_eq!(check!(fs::read_link(&tmpdir.join("bar"))).to_str().unwrap(),
                       "foo");
        }

        #[test]
        fn read_link() {
            if cfg!(windows) {
                // directory symlink
                assert_eq!(check!(fs::read_link(r"C:\Users\All Users")).to_str().unwrap(),
                           r"C:\ProgramData");
                // junction
                assert_eq!(check!(fs::read_link(r"C:\Users\Default User")).to_str().unwrap(),
                           r"C:\Users\Default");
                // junction with special permissions
                assert_eq!(check!(fs::read_link(r"C:\Documents and Settings\")).to_str().unwrap(),
                           r"C:\Users");
            }
            let tmpdir = tmpdir();
            let link = tmpdir.join("link");
            if !got_symlink_permission(&tmpdir) { return };
            check!(symlink_file(&"foo", &link));
            assert_eq!(check!(fs::read_link(&link)).to_str().unwrap(), "foo");
        }

        #[test]
        fn readlink_not_symlink() {
            let tmpdir = tmpdir();
            match fs::read_link(tmpdir.path()) {
                Ok(..) => panic!("wanted a failure"),
                Err(..) => {}
            }
        }

        #[test]
        fn links_work() {
            let tmpdir = tmpdir();
            let input = tmpdir.join("in.txt");
            let out = tmpdir.join("out.txt");

            check!(check!(File::create(&input)).write("foobar".as_bytes()));
            check!(fs::hard_link(&input, &out));
            assert_eq!(check!(fs::metadata(&out)).len(),
                       check!(fs::metadata(&input)).len());
            assert_eq!(check!(fs::metadata(&out)).len(),
                       check!(input.metadata()).len());
            let mut v = Vec::new();
            check!(check!(File::open(&out)).read_to_end(&mut v));
            assert_eq!(v, b"foobar".to_vec());

            // can't link to yourself
            match fs::hard_link(&input, &input) {
                Ok(..) => panic!("wanted a failure"),
                Err(..) => {}
            }
            // can't link to something that doesn't exist
            match fs::hard_link(&tmpdir.join("foo"), &tmpdir.join("bar")) {
                Ok(..) => panic!("wanted a failure"),
                Err(..) => {}
            }
        }

        #[test]
        fn chmod_works() {
            let tmpdir = tmpdir();
            let file = tmpdir.join("in.txt");

            check!(File::create(&file));
            let attr = check!(fs::metadata(&file));
            assert!(!attr.permissions().readonly());
            let mut p = attr.permissions();
            p.set_readonly(true);
            check!(fs::set_permissions(&file, p.clone()));
            let attr = check!(fs::metadata(&file));
            assert!(attr.permissions().readonly());

            match fs::set_permissions(&tmpdir.join("foo"), p.clone()) {
                Ok(..) => panic!("wanted an error"),
                Err(..) => {}
            }

            p.set_readonly(false);
            check!(fs::set_permissions(&file, p));
        }

        #[test]
        fn sync_doesnt_kill_anything() {
            let tmpdir = tmpdir();
            let path = tmpdir.join("in.txt");

            let mut file = check!(File::create(&path));
            check!(file.sync_all());
            check!(file.sync_data());
            check!(file.write(b"foo"));
            check!(file.sync_all());
            check!(file.sync_data());
        }

        #[test]
        fn truncate_works() {
            let tmpdir = tmpdir();
            let path = tmpdir.join("in.txt");

            let mut file = check!(File::create(&path));
            check!(file.write(b"foo"));
            check!(file.sync_all());

            // Do some simple things with truncation
            assert_eq!(check!(file.metadata()).len(), 3);
            check!(file.set_len(10));
            assert_eq!(check!(file.metadata()).len(), 10);
            check!(file.write(b"bar"));
            check!(file.sync_all());
            assert_eq!(check!(file.metadata()).len(), 10);

            let mut v = Vec::new();
            check!(check!(File::open(&path)).read_to_end(&mut v));
            assert_eq!(v, b"foobar\0\0\0\0".to_vec());

            // Truncate to a smaller length, don't seek, and then write something.
            // Ensure that the intermediate zeroes are all filled in (we have `seek`ed
            // past the end of the file).
            check!(file.set_len(2));
            assert_eq!(check!(file.metadata()).len(), 2);
            check!(file.write(b"wut"));
            check!(file.sync_all());
            assert_eq!(check!(file.metadata()).len(), 9);
            let mut v = Vec::new();
            check!(check!(File::open(&path)).read_to_end(&mut v));
            assert_eq!(v, b"fo\0\0\0\0wut".to_vec());
        }

        #[test]
        fn open_flavors() {
            use fs::OpenOptions as OO;
            fn c<T: Clone>(t: &T) -> T { t.clone() }

            let tmpdir = tmpdir();

            let mut r = OO::new(); r.read(true);
            let mut w = OO::new(); w.write(true);
            let mut rw = OO::new(); rw.read(true).write(true);
            let mut a = OO::new(); a.append(true);
            let mut ra = OO::new(); ra.read(true).append(true);

            let invalid_options = if cfg!(windows) { "The parameter is incorrect" }
                                  else { "Invalid argument" };

            // Test various combinations of creation modes and access modes.
            //
            // Allowed:
            // creation mode           | read  | write | read-write | append | read-append |
            // :-----------------------|:-----:|:-----:|:----------:|:------:|:-----------:|
            // not set (open existing) |   X   |   X   |     X      |   X    |      X      |
            // create                  |       |   X   |     X      |   X    |      X      |
            // truncate                |       |   X   |     X      |        |             |
            // create and truncate     |       |   X   |     X      |        |             |
            // create_new              |       |   X   |     X      |   X    |      X      |
            //
            // tested in reverse order, so 'create_new' creates the file, and 'open existing' opens it.

            // write-only
            check!(c(&w).create_new(true).open(&tmpdir.join("a")));
            check!(c(&w).create(true).truncate(true).open(&tmpdir.join("a")));
            check!(c(&w).truncate(true).open(&tmpdir.join("a")));
            check!(c(&w).create(true).open(&tmpdir.join("a")));
            check!(c(&w).open(&tmpdir.join("a")));

            // read-only
            error!(c(&r).create_new(true).open(&tmpdir.join("b")), invalid_options);
            error!(c(&r).create(true).truncate(true).open(&tmpdir.join("b")), invalid_options);
            error!(c(&r).truncate(true).open(&tmpdir.join("b")), invalid_options);
            error!(c(&r).create(true).open(&tmpdir.join("b")), invalid_options);
            check!(c(&r).open(&tmpdir.join("a"))); // try opening the file created with write_only

            // read-write
            check!(c(&rw).create_new(true).open(&tmpdir.join("c")));
            check!(c(&rw).create(true).truncate(true).open(&tmpdir.join("c")));
            check!(c(&rw).truncate(true).open(&tmpdir.join("c")));
            check!(c(&rw).create(true).open(&tmpdir.join("c")));
            check!(c(&rw).open(&tmpdir.join("c")));

            // append
            check!(c(&a).create_new(true).open(&tmpdir.join("d")));
            error!(c(&a).create(true).truncate(true).open(&tmpdir.join("d")), invalid_options);
            error!(c(&a).truncate(true).open(&tmpdir.join("d")), invalid_options);
            check!(c(&a).create(true).open(&tmpdir.join("d")));
            check!(c(&a).open(&tmpdir.join("d")));

            // read-append
            check!(c(&ra).create_new(true).open(&tmpdir.join("e")));
            error!(c(&ra).create(true).truncate(true).open(&tmpdir.join("e")), invalid_options);
            error!(c(&ra).truncate(true).open(&tmpdir.join("e")), invalid_options);
            check!(c(&ra).create(true).open(&tmpdir.join("e")));
            check!(c(&ra).open(&tmpdir.join("e")));

            // Test opening a file without setting an access mode
            let mut blank = OO::new();
             error!(blank.create(true).open(&tmpdir.join("f")), invalid_options);

            // Test write works
            check!(check!(File::create(&tmpdir.join("h"))).write("foobar".as_bytes()));

            // Test write fails for read-only
            check!(r.open(&tmpdir.join("h")));
            {
                let mut f = check!(r.open(&tmpdir.join("h")));
                assert!(f.write("wut".as_bytes()).is_err());
            }

            // Test write overwrites
            {
                let mut f = check!(c(&w).open(&tmpdir.join("h")));
                check!(f.write("baz".as_bytes()));
            }
            {
                let mut f = check!(c(&r).open(&tmpdir.join("h")));
                let mut b = vec![0; 6];
                check!(f.read(&mut b));
                assert_eq!(b, "bazbar".as_bytes());
            }

            // Test truncate works
            {
                let mut f = check!(c(&w).truncate(true).open(&tmpdir.join("h")));
                check!(f.write("foo".as_bytes()));
            }
            assert_eq!(check!(fs::metadata(&tmpdir.join("h"))).len(), 3);

            // Test append works
            assert_eq!(check!(fs::metadata(&tmpdir.join("h"))).len(), 3);
            {
                let mut f = check!(c(&a).open(&tmpdir.join("h")));
                check!(f.write("bar".as_bytes()));
            }
            assert_eq!(check!(fs::metadata(&tmpdir.join("h"))).len(), 6);

            // Test .append(true) equals .write(true).append(true)
            {
                let mut f = check!(c(&w).append(true).open(&tmpdir.join("h")));
                check!(f.write("baz".as_bytes()));
            }
            assert_eq!(check!(fs::metadata(&tmpdir.join("h"))).len(), 9);
        }

        #[test]
        fn _assert_send_sync() {
            fn _assert_send_sync<T: Send + Sync>() {}
            _assert_send_sync::<OpenOptions>();
        }

        #[test]
        fn binary_file() {
            let mut bytes = [0; 1024];
            StdRng::new().unwrap().fill_bytes(&mut bytes);

            let tmpdir = tmpdir();

            check!(check!(File::create(&tmpdir.join("test"))).write(&bytes));
            let mut v = Vec::new();
            check!(check!(File::open(&tmpdir.join("test"))).read_to_end(&mut v));
            assert!(v == &bytes[..]);
        }

        #[test]
        fn file_try_clone() {
            let tmpdir = tmpdir();

            let mut f1 = check!(OpenOptions::new()
                                           .read(true)
                                           .write(true)
                                           .create(true)
                                           .open(&tmpdir.join("test")));
            let mut f2 = check!(f1.try_clone());

            check!(f1.write_all(b"hello world"));
            check!(f1.seek(SeekFrom::Start(2)));

            let mut buf = vec![];
            check!(f2.read_to_end(&mut buf));
            assert_eq!(buf, b"llo world");
            drop(f2);

            check!(f1.write_all(b"!"));
        }

        #[test]
        #[cfg(not(windows))]
        fn unlink_readonly() {
            let tmpdir = tmpdir();
            let path = tmpdir.join("file");
            check!(File::create(&path));
            let mut perm = check!(fs::metadata(&path)).permissions();
            perm.set_readonly(true);
            check!(fs::set_permissions(&path, perm));
            check!(fs::remove_file(&path));
        }

        #[test]
        fn mkdir_trailing_slash() {
            let tmpdir = tmpdir();
            let path = tmpdir.join("file");
            check!(fs::create_dir_all(&path.join("a/")));
        }

        #[test]
        fn canonicalize_works_simple() {
            let tmpdir = tmpdir();
            let tmpdir = fs::canonicalize(tmpdir.path()).unwrap();
            let file = tmpdir.join("test");
            File::create(&file).unwrap();
            assert_eq!(fs::canonicalize(&file).unwrap(), file);
        }

        #[test]
        fn realpath_works() {
            let tmpdir = tmpdir();
            if !got_symlink_permission(&tmpdir) { return };

            let tmpdir = fs::canonicalize(tmpdir.path()).unwrap();
            let file = tmpdir.join("test");
            let dir = tmpdir.join("test2");
            let link = dir.join("link");
            let linkdir = tmpdir.join("test3");

            File::create(&file).unwrap();
            fs::create_dir(&dir).unwrap();
            symlink_file(&file, &link).unwrap();
            symlink_dir(&dir, &linkdir).unwrap();

            assert!(link.symlink_metadata().unwrap().file_type().is_symlink());

            assert_eq!(fs::canonicalize(&tmpdir).unwrap(), tmpdir);
            assert_eq!(fs::canonicalize(&file).unwrap(), file);
            assert_eq!(fs::canonicalize(&link).unwrap(), file);
            assert_eq!(fs::canonicalize(&linkdir).unwrap(), dir);
            assert_eq!(fs::canonicalize(&linkdir.join("link")).unwrap(), file);
        }

        #[test]
        fn realpath_works_tricky() {
            let tmpdir = tmpdir();
            if !got_symlink_permission(&tmpdir) { return };

            let tmpdir = fs::canonicalize(tmpdir.path()).unwrap();
            let a = tmpdir.join("a");
            let b = a.join("b");
            let c = b.join("c");
            let d = a.join("d");
            let e = d.join("e");
            let f = a.join("f");

            fs::create_dir_all(&b).unwrap();
            fs::create_dir_all(&d).unwrap();
            File::create(&f).unwrap();
            if cfg!(not(windows)) {
                symlink_dir("../d/e", &c).unwrap();
                symlink_file("../f", &e).unwrap();
            }
            if cfg!(windows) {
                symlink_dir(r"..\d\e", &c).unwrap();
                symlink_file(r"..\f", &e).unwrap();
            }

            assert_eq!(fs::canonicalize(&c).unwrap(), f);
            assert_eq!(fs::canonicalize(&e).unwrap(), f);
        }

        #[test]
        fn dir_entry_methods() {
            let tmpdir = tmpdir();

            fs::create_dir_all(&tmpdir.join("a")).unwrap();
            File::create(&tmpdir.join("b")).unwrap();

            for file in tmpdir.path().read_dir().unwrap().map(|f| f.unwrap()) {
                let fname = file.file_name();
                match fname.to_str() {
                    Some("a") => {
                        assert!(file.file_type().unwrap().is_dir());
                        assert!(file.metadata().unwrap().is_dir());
                    }
                    Some("b") => {
                        assert!(file.file_type().unwrap().is_file());
                        assert!(file.metadata().unwrap().is_file());
                    }
                    f => panic!("unknown file name: {:?}", f),
                }
            }
        }

        #[test]
        fn read_dir_not_found() {
            let res = fs::read_dir("/path/that/does/not/exist");
            assert_eq!(res.err().unwrap().kind(), ErrorKind::NotFound);
        }

        #[test]
        fn create_dir_all_with_junctions() {
            let tmpdir = tmpdir();
            let target = tmpdir.join("target");

            let junction = tmpdir.join("junction");
            let b = junction.join("a/b");

            let link = tmpdir.join("link");
            let d = link.join("c/d");

            fs::create_dir(&target).unwrap();

            check!(symlink_junction(&target, &junction));
            check!(fs::create_dir_all(&b));
            // the junction itself is not a directory, but `is_dir()` on a Path
            // follows links
            assert!(junction.is_dir());
            assert!(b.exists());

            if !got_symlink_permission(&tmpdir) { return };
            check!(symlink_dir(&target, &link));
            check!(fs::create_dir_all(&d));
            assert!(link.is_dir());
            assert!(d.exists());
        }

        #[test]
        fn metadata_access_times() {
            let tmpdir = tmpdir();

            let b = tmpdir.join("b");
            File::create(&b).unwrap();

            let a = check!(fs::metadata(&tmpdir.path()));
            let b = check!(fs::metadata(&b));

            assert_eq!(check!(a.accessed()), check!(a.accessed()));
            assert_eq!(check!(a.modified()), check!(a.modified()));
            assert_eq!(check!(b.accessed()), check!(b.modified()));

            if cfg!(target_os = "macos") || cfg!(target_os = "windows") {
                check!(a.created());
                check!(b.created());
            }
        }
    }

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