library/std/src/io/error.rs - toolchain/rustc - Git at Google

 #[cfg(test)]
 mod tests;

 use crate::convert::From;
 use crate::error;
 use crate::fmt;
 use crate::result;
 use crate::sys;

 /// A specialized [`Result`] type for I/O operations.
 ///
 /// This type is broadly used across [`std::io`] for any operation which may
 /// produce an error.
 ///
 /// This typedef is generally used to avoid writing out [`io::Error`] directly and
 /// is otherwise a direct mapping to [`Result`].
 ///
 /// While usual Rust style is to import types directly, aliases of [`Result`]
 /// often are not, to make it easier to distinguish between them. [`Result`] is
 /// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
 /// will generally use `io::Result` instead of shadowing the [prelude]'s import
 /// of [`std::result::Result`][`Result`].
 ///
 /// [`std::io`]: crate::io
 /// [`io::Error`]: Error
 /// [`Result`]: crate::result::Result
 /// [prelude]: crate::prelude
 ///
 /// # Examples
 ///
 /// A convenience function that bubbles an `io::Result` to its caller:
 ///
 /// ```
 /// use std::io;
 ///
 /// fn get_string() -> io::Result<String> {
 ///     let mut buffer = String::new();
 ///
 ///     io::stdin().read_line(&mut buffer)?;
 ///
 ///     Ok(buffer)
 /// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub type Result<T> = result::Result<T, Error>;

 /// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
 /// associated traits.
 ///
 /// Errors mostly originate from the underlying OS, but custom instances of
 /// `Error` can be created with crafted error messages and a particular value of
 /// [`ErrorKind`].
 ///
 /// [`Read`]: crate::io::Read
 /// [`Write`]: crate::io::Write
 /// [`Seek`]: crate::io::Seek
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Error {
     repr: Repr,
 }

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

 enum Repr {
     Os(i32),
     Simple(ErrorKind),
     // &str is a fat pointer, but &&str is a thin pointer.
     SimpleMessage(ErrorKind, &'static &'static str),
     Custom(Box<Custom>),
 }

 #[derive(Debug)]
 struct Custom {
     kind: ErrorKind,
     error: Box<dyn error::Error + Send + Sync>,
 }

 /// A list specifying general categories of I/O error.
 ///
 /// This list is intended to grow over time and it is not recommended to
 /// exhaustively match against it.
 ///
 /// It is used with the [`io::Error`] type.
 ///
 /// [`io::Error`]: Error
 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[allow(deprecated)]
 #[non_exhaustive]
 pub enum ErrorKind {
     /// An entity was not found, often a file.
     #[stable(feature = "rust1", since = "1.0.0")]
     NotFound,
     /// The operation lacked the necessary privileges to complete.
     #[stable(feature = "rust1", since = "1.0.0")]
     PermissionDenied,
     /// The connection was refused by the remote server.
     #[stable(feature = "rust1", since = "1.0.0")]
     ConnectionRefused,
     /// The connection was reset by the remote server.
     #[stable(feature = "rust1", since = "1.0.0")]
     ConnectionReset,
     /// The connection was aborted (terminated) by the remote server.
     #[stable(feature = "rust1", since = "1.0.0")]
     ConnectionAborted,
     /// The network operation failed because it was not connected yet.
     #[stable(feature = "rust1", since = "1.0.0")]
     NotConnected,
     /// A socket address could not be bound because the address is already in
     /// use elsewhere.
     #[stable(feature = "rust1", since = "1.0.0")]
     AddrInUse,
     /// A nonexistent interface was requested or the requested address was not
     /// local.
     #[stable(feature = "rust1", since = "1.0.0")]
     AddrNotAvailable,
     /// The operation failed because a pipe was closed.
     #[stable(feature = "rust1", since = "1.0.0")]
     BrokenPipe,
     /// An entity already exists, often a file.
     #[stable(feature = "rust1", since = "1.0.0")]
     AlreadyExists,
     /// The operation needs to block to complete, but the blocking operation was
     /// requested to not occur.
     #[stable(feature = "rust1", since = "1.0.0")]
     WouldBlock,
     /// A parameter was incorrect.
     #[stable(feature = "rust1", since = "1.0.0")]
     InvalidInput,
     /// Data not valid for the operation were encountered.
     ///
     /// Unlike [`InvalidInput`], this typically means that the operation
     /// parameters were valid, however the error was caused by malformed
     /// input data.
     ///
     /// For example, a function that reads a file into a string will error with
     /// `InvalidData` if the file's contents are not valid UTF-8.
     ///
     /// [`InvalidInput`]: ErrorKind::InvalidInput
     #[stable(feature = "io_invalid_data", since = "1.2.0")]
     InvalidData,
     /// The I/O operation's timeout expired, causing it to be canceled.
     #[stable(feature = "rust1", since = "1.0.0")]
     TimedOut,
     /// An error returned when an operation could not be completed because a
     /// call to [`write`] returned [`Ok(0)`].
     ///
     /// This typically means that an operation could only succeed if it wrote a
     /// particular number of bytes but only a smaller number of bytes could be
     /// written.
     ///
     /// [`write`]: crate::io::Write::write
     /// [`Ok(0)`]: Ok
     #[stable(feature = "rust1", since = "1.0.0")]
     WriteZero,
     /// This operation was interrupted.
     ///
     /// Interrupted operations can typically be retried.
     #[stable(feature = "rust1", since = "1.0.0")]
     Interrupted,
     /// Any I/O error not part of this list.
     ///
     /// Errors that are `Other` now may move to a different or a new
     /// [`ErrorKind`] variant in the future. It is not recommended to match
     /// an error against `Other` and to expect any additional characteristics,
     /// e.g., a specific [`Error::raw_os_error`] return value.
     #[stable(feature = "rust1", since = "1.0.0")]
     Other,

     /// An error returned when an operation could not be completed because an
     /// "end of file" was reached prematurely.
     ///
     /// This typically means that an operation could only succeed if it read a
     /// particular number of bytes but only a smaller number of bytes could be
     /// read.
     #[stable(feature = "read_exact", since = "1.6.0")]
     UnexpectedEof,

     /// This operation is unsupported on this platform.
     ///
     /// This means that the operation can never succeed.
     #[stable(feature = "unsupported_error", since = "1.53.0")]
     Unsupported,
 }

 impl ErrorKind {
     pub(crate) fn as_str(&self) -> &'static str {
         match *self {
             ErrorKind::NotFound => "entity not found",
             ErrorKind::PermissionDenied => "permission denied",
             ErrorKind::ConnectionRefused => "connection refused",
             ErrorKind::ConnectionReset => "connection reset",
             ErrorKind::ConnectionAborted => "connection aborted",
             ErrorKind::NotConnected => "not connected",
             ErrorKind::AddrInUse => "address in use",
             ErrorKind::AddrNotAvailable => "address not available",
             ErrorKind::BrokenPipe => "broken pipe",
             ErrorKind::AlreadyExists => "entity already exists",
             ErrorKind::WouldBlock => "operation would block",
             ErrorKind::InvalidInput => "invalid input parameter",
             ErrorKind::InvalidData => "invalid data",
             ErrorKind::TimedOut => "timed out",
             ErrorKind::WriteZero => "write zero",
             ErrorKind::Interrupted => "operation interrupted",
             ErrorKind::Other => "other os error",
             ErrorKind::UnexpectedEof => "unexpected end of file",
             ErrorKind::Unsupported => "unsupported",
         }
     }
 }

 /// Intended for use for errors not exposed to the user, where allocating onto
 /// the heap (for normal construction via Error::new) is too costly.
 #[stable(feature = "io_error_from_errorkind", since = "1.14.0")]
 impl From<ErrorKind> for Error {
     /// Converts an [`ErrorKind`] into an [`Error`].
     ///
     /// This conversion allocates a new error with a simple representation of error kind.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::io::{Error, ErrorKind};
     ///
     /// let not_found = ErrorKind::NotFound;
     /// let error = Error::from(not_found);
     /// assert_eq!("entity not found", format!("{}", error));
     /// ```
     #[inline]
     fn from(kind: ErrorKind) -> Error {
         Error { repr: Repr::Simple(kind) }
     }
 }

 impl Error {
     /// Creates a new I/O error from a known kind of error as well as an
     /// arbitrary error payload.
     ///
     /// This function is used to generically create I/O errors which do not
     /// originate from the OS itself. The `error` argument is an arbitrary
     /// payload which will be contained in this [`Error`].
     ///
     /// # Examples
     ///
     /// ```
     /// use std::io::{Error, ErrorKind};
     ///
     /// // errors can be created from strings
     /// let custom_error = Error::new(ErrorKind::Other, "oh no!");
     ///
     /// // errors can also be created from other errors
     /// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new<E>(kind: ErrorKind, error: E) -> Error
     where
         E: Into<Box<dyn error::Error + Send + Sync>>,
     {
         Self::_new(kind, error.into())
     }

     fn _new(kind: ErrorKind, error: Box<dyn error::Error + Send + Sync>) -> Error {
         Error { repr: Repr::Custom(Box::new(Custom { kind, error })) }
     }

     /// Creates a new I/O error from a known kind of error as well as a
     /// constant message.
     ///
     /// This function does not allocate.
     ///
     /// This function should maybe change to
     /// `new_const<const MSG: &'static str>(kind: ErrorKind)`
     /// in the future, when const generics allow that.
     #[inline]
     pub(crate) const fn new_const(kind: ErrorKind, message: &'static &'static str) -> Error {
         Self { repr: Repr::SimpleMessage(kind, message) }
     }

     /// Returns an error representing the last OS error which occurred.
     ///
     /// This function reads the value of `errno` for the target platform (e.g.
     /// `GetLastError` on Windows) and will return a corresponding instance of
     /// [`Error`] for the error code.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::io::Error;
     ///
     /// println!("last OS error: {:?}", Error::last_os_error());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn last_os_error() -> Error {
         Error::from_raw_os_error(sys::os::errno() as i32)
     }

     /// Creates a new instance of an [`Error`] from a particular OS error code.
     ///
     /// # Examples
     ///
     /// On Linux:
     ///
     /// ```
     /// # if cfg!(target_os = "linux") {
     /// use std::io;
     ///
     /// let error = io::Error::from_raw_os_error(22);
     /// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
     /// # }
     /// ```
     ///
     /// On Windows:
     ///
     /// ```
     /// # if cfg!(windows) {
     /// use std::io;
     ///
     /// let error = io::Error::from_raw_os_error(10022);
     /// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
     /// # }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn from_raw_os_error(code: i32) -> Error {
         Error { repr: Repr::Os(code) }
     }

     /// Returns the OS error that this error represents (if any).
     ///
     /// If this [`Error`] was constructed via [`last_os_error`] or
     /// [`from_raw_os_error`], then this function will return [`Some`], otherwise
     /// it will return [`None`].
     ///
     /// [`last_os_error`]: Error::last_os_error
     /// [`from_raw_os_error`]: Error::from_raw_os_error
     ///
     /// # Examples
     ///
     /// ```
     /// use std::io::{Error, ErrorKind};
     ///
     /// fn print_os_error(err: &Error) {
     ///     if let Some(raw_os_err) = err.raw_os_error() {
     ///         println!("raw OS error: {:?}", raw_os_err);
     ///     } else {
     ///         println!("Not an OS error");
     ///     }
     /// }
     ///
     /// fn main() {
     ///     // Will print "raw OS error: ...".
     ///     print_os_error(&Error::last_os_error());
     ///     // Will print "Not an OS error".
     ///     print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
     /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn raw_os_error(&self) -> Option<i32> {
         match self.repr {
             Repr::Os(i) => Some(i),
             Repr::Custom(..) => None,
             Repr::Simple(..) => None,
             Repr::SimpleMessage(..) => None,
         }
     }

     /// Returns a reference to the inner error wrapped by this error (if any).
     ///
     /// If this [`Error`] was constructed via [`new`] then this function will
     /// return [`Some`], otherwise it will return [`None`].
     ///
     /// [`new`]: Error::new
     ///
     /// # Examples
     ///
     /// ```
     /// use std::io::{Error, ErrorKind};
     ///
     /// fn print_error(err: &Error) {
     ///     if let Some(inner_err) = err.get_ref() {
     ///         println!("Inner error: {:?}", inner_err);
     ///     } else {
     ///         println!("No inner error");
     ///     }
     /// }
     ///
     /// fn main() {
     ///     // Will print "No inner error".
     ///     print_error(&Error::last_os_error());
     ///     // Will print "Inner error: ...".
     ///     print_error(&Error::new(ErrorKind::Other, "oh no!"));
     /// }
     /// ```
     #[stable(feature = "io_error_inner", since = "1.3.0")]
     #[inline]
     pub fn get_ref(&self) -> Option<&(dyn error::Error + Send + Sync + 'static)> {
         match self.repr {
             Repr::Os(..) => None,
             Repr::Simple(..) => None,
             Repr::SimpleMessage(..) => None,
             Repr::Custom(ref c) => Some(&*c.error),
         }
     }

     /// Returns a mutable reference to the inner error wrapped by this error
     /// (if any).
     ///
     /// If this [`Error`] was constructed via [`new`] then this function will
     /// return [`Some`], otherwise it will return [`None`].
     ///
     /// [`new`]: Error::new
     ///
     /// # Examples
     ///
     /// ```
     /// use std::io::{Error, ErrorKind};
     /// use std::{error, fmt};
     /// use std::fmt::Display;
     ///
     /// #[derive(Debug)]
     /// struct MyError {
     ///     v: String,
     /// }
     ///
     /// impl MyError {
     ///     fn new() -> MyError {
     ///         MyError {
     ///             v: "oh no!".to_string()
     ///         }
     ///     }
     ///
     ///     fn change_message(&mut self, new_message: &str) {
     ///         self.v = new_message.to_string();
     ///     }
     /// }
     ///
     /// impl error::Error for MyError {}
     ///
     /// impl Display for MyError {
     ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f, "MyError: {}", &self.v)
     ///     }
     /// }
     ///
     /// fn change_error(mut err: Error) -> Error {
     ///     if let Some(inner_err) = err.get_mut() {
     ///         inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
     ///     }
     ///     err
     /// }
     ///
     /// fn print_error(err: &Error) {
     ///     if let Some(inner_err) = err.get_ref() {
     ///         println!("Inner error: {}", inner_err);
     ///     } else {
     ///         println!("No inner error");
     ///     }
     /// }
     ///
     /// fn main() {
     ///     // Will print "No inner error".
     ///     print_error(&change_error(Error::last_os_error()));
     ///     // Will print "Inner error: ...".
     ///     print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
     /// }
     /// ```
     #[stable(feature = "io_error_inner", since = "1.3.0")]
     #[inline]
     pub fn get_mut(&mut self) -> Option<&mut (dyn error::Error + Send + Sync + 'static)> {
         match self.repr {
             Repr::Os(..) => None,
             Repr::Simple(..) => None,
             Repr::SimpleMessage(..) => None,
             Repr::Custom(ref mut c) => Some(&mut *c.error),
         }
     }

     /// Consumes the `Error`, returning its inner error (if any).
     ///
     /// If this [`Error`] was constructed via [`new`] then this function will
     /// return [`Some`], otherwise it will return [`None`].
     ///
     /// [`new`]: Error::new
     ///
     /// # Examples
     ///
     /// ```
     /// use std::io::{Error, ErrorKind};
     ///
     /// fn print_error(err: Error) {
     ///     if let Some(inner_err) = err.into_inner() {
     ///         println!("Inner error: {}", inner_err);
     ///     } else {
     ///         println!("No inner error");
     ///     }
     /// }
     ///
     /// fn main() {
     ///     // Will print "No inner error".
     ///     print_error(Error::last_os_error());
     ///     // Will print "Inner error: ...".
     ///     print_error(Error::new(ErrorKind::Other, "oh no!"));
     /// }
     /// ```
     #[stable(feature = "io_error_inner", since = "1.3.0")]
     #[inline]
     pub fn into_inner(self) -> Option<Box<dyn error::Error + Send + Sync>> {
         match self.repr {
             Repr::Os(..) => None,
             Repr::Simple(..) => None,
             Repr::SimpleMessage(..) => None,
             Repr::Custom(c) => Some(c.error),
         }
     }

     /// Returns the corresponding [`ErrorKind`] for this error.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::io::{Error, ErrorKind};
     ///
     /// fn print_error(err: Error) {
     ///     println!("{:?}", err.kind());
     /// }
     ///
     /// fn main() {
     ///     // Will print "Other".
     ///     print_error(Error::last_os_error());
     ///     // Will print "AddrInUse".
     ///     print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
     /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn kind(&self) -> ErrorKind {
         match self.repr {
             Repr::Os(code) => sys::decode_error_kind(code),
             Repr::Custom(ref c) => c.kind,
             Repr::Simple(kind) => kind,
             Repr::SimpleMessage(kind, _) => kind,
         }
     }
 }

 impl fmt::Debug for Repr {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
             Repr::Os(code) => fmt
                 .debug_struct("Os")
                 .field("code", &code)
                 .field("kind", &sys::decode_error_kind(code))
                 .field("message", &sys::os::error_string(code))
                 .finish(),
             Repr::Custom(ref c) => fmt::Debug::fmt(&c, fmt),
             Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
             Repr::SimpleMessage(kind, &message) => {
                 fmt.debug_struct("Error").field("kind", &kind).field("message", &message).finish()
             }
         }
     }
 }

 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Display for Error {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self.repr {
             Repr::Os(code) => {
                 let detail = sys::os::error_string(code);
                 write!(fmt, "{} (os error {})", detail, code)
             }
             Repr::Custom(ref c) => c.error.fmt(fmt),
             Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
             Repr::SimpleMessage(_, &msg) => msg.fmt(fmt),
         }
     }
 }

 #[stable(feature = "rust1", since = "1.0.0")]
 impl error::Error for Error {
     #[allow(deprecated, deprecated_in_future)]
     fn description(&self) -> &str {
         match self.repr {
             Repr::Os(..) | Repr::Simple(..) => self.kind().as_str(),
             Repr::SimpleMessage(_, &msg) => msg,
             Repr::Custom(ref c) => c.error.description(),
         }
     }

     #[allow(deprecated)]
     fn cause(&self) -> Option<&dyn error::Error> {
         match self.repr {
             Repr::Os(..) => None,
             Repr::Simple(..) => None,
             Repr::SimpleMessage(..) => None,
             Repr::Custom(ref c) => c.error.cause(),
         }
     }

     fn source(&self) -> Option<&(dyn error::Error + 'static)> {
         match self.repr {
             Repr::Os(..) => None,
             Repr::Simple(..) => None,
             Repr::SimpleMessage(..) => None,
             Repr::Custom(ref c) => c.error.source(),
         }
     }
 }

 fn _assert_error_is_sync_send() {
     fn _is_sync_send<T: Sync + Send>() {}
     _is_sync_send::<Error>();
 }
	#[cfg(test)]
	mod tests;

	use crate::convert::From;
	use crate::error;
	use crate::fmt;
	use crate::result;
	use crate::sys;

	/// A specialized [`Result`] type for I/O operations.
	///
	/// This type is broadly used across [`std::io`] for any operation which may
	/// produce an error.
	///
	/// This typedef is generally used to avoid writing out [`io::Error`] directly and
	/// is otherwise a direct mapping to [`Result`].
	///
	/// While usual Rust style is to import types directly, aliases of [`Result`]
	/// often are not, to make it easier to distinguish between them. [`Result`] is
	/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
	/// will generally use `io::Result` instead of shadowing the [prelude]'s import
	/// of [`std::result::Result`][`Result`].
	///
	/// [`std::io`]: crate::io
	/// [`io::Error`]: Error
	/// [`Result`]: crate::result::Result
	/// [prelude]: crate::prelude
	///
	/// # Examples
	///
	/// A convenience function that bubbles an `io::Result` to its caller:
	///
	/// ```
	/// use std::io;
	///
	/// fn get_string() -> io::Result<String> {
	/// let mut buffer = String::new();
	///
	/// io::stdin().read_line(&mut buffer)?;
	///
	/// Ok(buffer)
	/// }
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	pub type Result<T> = result::Result<T, Error>;

	/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
	/// associated traits.
	///
	/// Errors mostly originate from the underlying OS, but custom instances of
	/// `Error` can be created with crafted error messages and a particular value of
	/// [`ErrorKind`].
	///
	/// [`Read`]: crate::io::Read
	/// [`Write`]: crate::io::Write
	/// [`Seek`]: crate::io::Seek
	#[stable(feature = "rust1", since = "1.0.0")]
	pub struct Error {
	repr: Repr,
	}

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

	enum Repr {
	Os(i32),
	Simple(ErrorKind),
	// &str is a fat pointer, but &&str is a thin pointer.
	SimpleMessage(ErrorKind, &'static &'static str),
	Custom(Box<Custom>),
	}

	#[derive(Debug)]
	struct Custom {
	kind: ErrorKind,
	error: Box<dyn error::Error + Send + Sync>,
	}

	/// A list specifying general categories of I/O error.
	///
	/// This list is intended to grow over time and it is not recommended to
	/// exhaustively match against it.
	///
	/// It is used with the [`io::Error`] type.
	///
	/// [`io::Error`]: Error
	#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
	#[stable(feature = "rust1", since = "1.0.0")]
	#[allow(deprecated)]
	#[non_exhaustive]
	pub enum ErrorKind {
	/// An entity was not found, often a file.
	#[stable(feature = "rust1", since = "1.0.0")]
	NotFound,
	/// The operation lacked the necessary privileges to complete.
	#[stable(feature = "rust1", since = "1.0.0")]
	PermissionDenied,
	/// The connection was refused by the remote server.
	#[stable(feature = "rust1", since = "1.0.0")]
	ConnectionRefused,
	/// The connection was reset by the remote server.
	#[stable(feature = "rust1", since = "1.0.0")]
	ConnectionReset,
	/// The connection was aborted (terminated) by the remote server.
	#[stable(feature = "rust1", since = "1.0.0")]
	ConnectionAborted,
	/// The network operation failed because it was not connected yet.
	#[stable(feature = "rust1", since = "1.0.0")]
	NotConnected,
	/// A socket address could not be bound because the address is already in
	/// use elsewhere.
	#[stable(feature = "rust1", since = "1.0.0")]
	AddrInUse,
	/// A nonexistent interface was requested or the requested address was not
	/// local.
	#[stable(feature = "rust1", since = "1.0.0")]
	AddrNotAvailable,
	/// The operation failed because a pipe was closed.
	#[stable(feature = "rust1", since = "1.0.0")]
	BrokenPipe,
	/// An entity already exists, often a file.
	#[stable(feature = "rust1", since = "1.0.0")]
	AlreadyExists,
	/// The operation needs to block to complete, but the blocking operation was
	/// requested to not occur.
	#[stable(feature = "rust1", since = "1.0.0")]
	WouldBlock,
	/// A parameter was incorrect.
	#[stable(feature = "rust1", since = "1.0.0")]
	InvalidInput,
	/// Data not valid for the operation were encountered.
	///
	/// Unlike [`InvalidInput`], this typically means that the operation
	/// parameters were valid, however the error was caused by malformed
	/// input data.
	///
	/// For example, a function that reads a file into a string will error with
	/// `InvalidData` if the file's contents are not valid UTF-8.
	///
	/// [`InvalidInput`]: ErrorKind::InvalidInput
	#[stable(feature = "io_invalid_data", since = "1.2.0")]
	InvalidData,
	/// The I/O operation's timeout expired, causing it to be canceled.
	#[stable(feature = "rust1", since = "1.0.0")]
	TimedOut,
	/// An error returned when an operation could not be completed because a
	/// call to [`write`] returned [`Ok(0)`].
	///
	/// This typically means that an operation could only succeed if it wrote a
	/// particular number of bytes but only a smaller number of bytes could be
	/// written.
	///
	/// [`write`]: crate::io::Write::write
	/// [`Ok(0)`]: Ok
	#[stable(feature = "rust1", since = "1.0.0")]
	WriteZero,
	/// This operation was interrupted.
	///
	/// Interrupted operations can typically be retried.
	#[stable(feature = "rust1", since = "1.0.0")]
	Interrupted,
	/// Any I/O error not part of this list.
	///
	/// Errors that are `Other` now may move to a different or a new
	/// [`ErrorKind`] variant in the future. It is not recommended to match
	/// an error against `Other` and to expect any additional characteristics,
	/// e.g., a specific [`Error::raw_os_error`] return value.
	#[stable(feature = "rust1", since = "1.0.0")]
	Other,

	/// An error returned when an operation could not be completed because an
	/// "end of file" was reached prematurely.
	///
	/// This typically means that an operation could only succeed if it read a
	/// particular number of bytes but only a smaller number of bytes could be
	/// read.
	#[stable(feature = "read_exact", since = "1.6.0")]
	UnexpectedEof,

	/// This operation is unsupported on this platform.
	///
	/// This means that the operation can never succeed.
	#[stable(feature = "unsupported_error", since = "1.53.0")]
	Unsupported,
	}

	impl ErrorKind {
	pub(crate) fn as_str(&self) -> &'static str {
	match *self {
	ErrorKind::NotFound => "entity not found",
	ErrorKind::PermissionDenied => "permission denied",
	ErrorKind::ConnectionRefused => "connection refused",
	ErrorKind::ConnectionReset => "connection reset",
	ErrorKind::ConnectionAborted => "connection aborted",
	ErrorKind::NotConnected => "not connected",
	ErrorKind::AddrInUse => "address in use",
	ErrorKind::AddrNotAvailable => "address not available",
	ErrorKind::BrokenPipe => "broken pipe",
	ErrorKind::AlreadyExists => "entity already exists",
	ErrorKind::WouldBlock => "operation would block",
	ErrorKind::InvalidInput => "invalid input parameter",
	ErrorKind::InvalidData => "invalid data",
	ErrorKind::TimedOut => "timed out",
	ErrorKind::WriteZero => "write zero",
	ErrorKind::Interrupted => "operation interrupted",
	ErrorKind::Other => "other os error",
	ErrorKind::UnexpectedEof => "unexpected end of file",
	ErrorKind::Unsupported => "unsupported",
	}
	}
	}

	/// Intended for use for errors not exposed to the user, where allocating onto
	/// the heap (for normal construction via Error::new) is too costly.
	#[stable(feature = "io_error_from_errorkind", since = "1.14.0")]
	impl From<ErrorKind> for Error {
	/// Converts an [`ErrorKind`] into an [`Error`].
	///
	/// This conversion allocates a new error with a simple representation of error kind.
	///
	/// # Examples
	///
	/// ```
	/// use std::io::{Error, ErrorKind};
	///
	/// let not_found = ErrorKind::NotFound;
	/// let error = Error::from(not_found);
	/// assert_eq!("entity not found", format!("{}", error));
	/// ```
	#[inline]
	fn from(kind: ErrorKind) -> Error {
	Error { repr: Repr::Simple(kind) }
	}
	}

	impl Error {
	/// Creates a new I/O error from a known kind of error as well as an
	/// arbitrary error payload.
	///
	/// This function is used to generically create I/O errors which do not
	/// originate from the OS itself. The `error` argument is an arbitrary
	/// payload which will be contained in this [`Error`].
	///
	/// # Examples
	///
	/// ```
	/// use std::io::{Error, ErrorKind};
	///
	/// // errors can be created from strings
	/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
	///
	/// // errors can also be created from other errors
	/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	pub fn new<E>(kind: ErrorKind, error: E) -> Error
	where
	E: Into<Box<dyn error::Error + Send + Sync>>,
	{
	Self::_new(kind, error.into())
	}

	fn _new(kind: ErrorKind, error: Box<dyn error::Error + Send + Sync>) -> Error {
	Error { repr: Repr::Custom(Box::new(Custom { kind, error })) }
	}

	/// Creates a new I/O error from a known kind of error as well as a
	/// constant message.
	///
	/// This function does not allocate.
	///
	/// This function should maybe change to
	/// `new_const<const MSG: &'static str>(kind: ErrorKind)`
	/// in the future, when const generics allow that.
	#[inline]
	pub(crate) const fn new_const(kind: ErrorKind, message: &'static &'static str) -> Error {
	Self { repr: Repr::SimpleMessage(kind, message) }
	}

	/// Returns an error representing the last OS error which occurred.
	///
	/// This function reads the value of `errno` for the target platform (e.g.
	/// `GetLastError` on Windows) and will return a corresponding instance of
	/// [`Error`] for the error code.
	///
	/// # Examples
	///
	/// ```
	/// use std::io::Error;
	///
	/// println!("last OS error: {:?}", Error::last_os_error());
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[inline]
	pub fn last_os_error() -> Error {
	Error::from_raw_os_error(sys::os::errno() as i32)
	}

	/// Creates a new instance of an [`Error`] from a particular OS error code.
	///
	/// # Examples
	///
	/// On Linux:
	///
	/// ```
	/// # if cfg!(target_os = "linux") {
	/// use std::io;
	///
	/// let error = io::Error::from_raw_os_error(22);
	/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
	/// # }
	/// ```
	///
	/// On Windows:
	///
	/// ```
	/// # if cfg!(windows) {
	/// use std::io;
	///
	/// let error = io::Error::from_raw_os_error(10022);
	/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
	/// # }
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[inline]
	pub fn from_raw_os_error(code: i32) -> Error {
	Error { repr: Repr::Os(code) }
	}

	/// Returns the OS error that this error represents (if any).
	///
	/// If this [`Error`] was constructed via [`last_os_error`] or
	/// [`from_raw_os_error`], then this function will return [`Some`], otherwise
	/// it will return [`None`].
	///
	/// [`last_os_error`]: Error::last_os_error
	/// [`from_raw_os_error`]: Error::from_raw_os_error
	///
	/// # Examples
	///
	/// ```
	/// use std::io::{Error, ErrorKind};
	///
	/// fn print_os_error(err: &Error) {
	/// if let Some(raw_os_err) = err.raw_os_error() {
	/// println!("raw OS error: {:?}", raw_os_err);
	/// } else {
	/// println!("Not an OS error");
	/// }
	/// }
	///
	/// fn main() {
	/// // Will print "raw OS error: ...".
	/// print_os_error(&Error::last_os_error());
	/// // Will print "Not an OS error".
	/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
	/// }
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[inline]
	pub fn raw_os_error(&self) -> Option<i32> {
	match self.repr {
	Repr::Os(i) => Some(i),
	Repr::Custom(..) => None,
	Repr::Simple(..) => None,
	Repr::SimpleMessage(..) => None,
	}
	}

	/// Returns a reference to the inner error wrapped by this error (if any).
	///
	/// If this [`Error`] was constructed via [`new`] then this function will
	/// return [`Some`], otherwise it will return [`None`].
	///
	/// [`new`]: Error::new
	///
	/// # Examples
	///
	/// ```
	/// use std::io::{Error, ErrorKind};
	///
	/// fn print_error(err: &Error) {
	/// if let Some(inner_err) = err.get_ref() {
	/// println!("Inner error: {:?}", inner_err);
	/// } else {
	/// println!("No inner error");
	/// }
	/// }
	///
	/// fn main() {
	/// // Will print "No inner error".
	/// print_error(&Error::last_os_error());
	/// // Will print "Inner error: ...".
	/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
	/// }
	/// ```
	#[stable(feature = "io_error_inner", since = "1.3.0")]
	#[inline]
	pub fn get_ref(&self) -> Option<&(dyn error::Error + Send + Sync + 'static)> {
	match self.repr {
	Repr::Os(..) => None,
	Repr::Simple(..) => None,
	Repr::SimpleMessage(..) => None,
	Repr::Custom(ref c) => Some(&*c.error),
	}
	}

	/// Returns a mutable reference to the inner error wrapped by this error
	/// (if any).
	///
	/// If this [`Error`] was constructed via [`new`] then this function will
	/// return [`Some`], otherwise it will return [`None`].
	///
	/// [`new`]: Error::new
	///
	/// # Examples
	///
	/// ```
	/// use std::io::{Error, ErrorKind};
	/// use std::{error, fmt};
	/// use std::fmt::Display;
	///
	/// #[derive(Debug)]
	/// struct MyError {
	/// v: String,
	/// }
	///
	/// impl MyError {
	/// fn new() -> MyError {
	/// MyError {
	/// v: "oh no!".to_string()
	/// }
	/// }
	///
	/// fn change_message(&mut self, new_message: &str) {
	/// self.v = new_message.to_string();
	/// }
	/// }
	///
	/// impl error::Error for MyError {}
	///
	/// impl Display for MyError {
	/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	/// write!(f, "MyError: {}", &self.v)
	/// }
	/// }
	///
	/// fn change_error(mut err: Error) -> Error {
	/// if let Some(inner_err) = err.get_mut() {
	/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
	/// }
	/// err
	/// }
	///
	/// fn print_error(err: &Error) {
	/// if let Some(inner_err) = err.get_ref() {
	/// println!("Inner error: {}", inner_err);
	/// } else {
	/// println!("No inner error");
	/// }
	/// }
	///
	/// fn main() {
	/// // Will print "No inner error".
	/// print_error(&change_error(Error::last_os_error()));
	/// // Will print "Inner error: ...".
	/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
	/// }
	/// ```
	#[stable(feature = "io_error_inner", since = "1.3.0")]
	#[inline]
	pub fn get_mut(&mut self) -> Option<&mut (dyn error::Error + Send + Sync + 'static)> {
	match self.repr {
	Repr::Os(..) => None,
	Repr::Simple(..) => None,
	Repr::SimpleMessage(..) => None,
	Repr::Custom(ref mut c) => Some(&mut *c.error),
	}
	}

	/// Consumes the `Error`, returning its inner error (if any).
	///
	/// If this [`Error`] was constructed via [`new`] then this function will
	/// return [`Some`], otherwise it will return [`None`].
	///
	/// [`new`]: Error::new
	///
	/// # Examples
	///
	/// ```
	/// use std::io::{Error, ErrorKind};
	///
	/// fn print_error(err: Error) {
	/// if let Some(inner_err) = err.into_inner() {
	/// println!("Inner error: {}", inner_err);
	/// } else {
	/// println!("No inner error");
	/// }
	/// }
	///
	/// fn main() {
	/// // Will print "No inner error".
	/// print_error(Error::last_os_error());
	/// // Will print "Inner error: ...".
	/// print_error(Error::new(ErrorKind::Other, "oh no!"));
	/// }
	/// ```
	#[stable(feature = "io_error_inner", since = "1.3.0")]
	#[inline]
	pub fn into_inner(self) -> Option<Box<dyn error::Error + Send + Sync>> {
	match self.repr {
	Repr::Os(..) => None,
	Repr::Simple(..) => None,
	Repr::SimpleMessage(..) => None,
	Repr::Custom(c) => Some(c.error),
	}
	}

	/// Returns the corresponding [`ErrorKind`] for this error.
	///
	/// # Examples
	///
	/// ```
	/// use std::io::{Error, ErrorKind};
	///
	/// fn print_error(err: Error) {
	/// println!("{:?}", err.kind());
	/// }
	///
	/// fn main() {
	/// // Will print "Other".
	/// print_error(Error::last_os_error());
	/// // Will print "AddrInUse".
	/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
	/// }
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[inline]
	pub fn kind(&self) -> ErrorKind {
	match self.repr {
	Repr::Os(code) => sys::decode_error_kind(code),
	Repr::Custom(ref c) => c.kind,
	Repr::Simple(kind) => kind,
	Repr::SimpleMessage(kind, _) => kind,
	}
	}
	}

	impl fmt::Debug for Repr {
	fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
	match *self {
	Repr::Os(code) => fmt
	.debug_struct("Os")
	.field("code", &code)
	.field("kind", &sys::decode_error_kind(code))
	.field("message", &sys::os::error_string(code))
	.finish(),
	Repr::Custom(ref c) => fmt::Debug::fmt(&c, fmt),
	Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
	Repr::SimpleMessage(kind, &message) => {
	fmt.debug_struct("Error").field("kind", &kind).field("message", &message).finish()
	}
	}
	}
	}

	#[stable(feature = "rust1", since = "1.0.0")]
	impl fmt::Display for Error {
	fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
	match self.repr {
	Repr::Os(code) => {
	let detail = sys::os::error_string(code);
	write!(fmt, "{} (os error {})", detail, code)
	}
	Repr::Custom(ref c) => c.error.fmt(fmt),
	Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
	Repr::SimpleMessage(_, &msg) => msg.fmt(fmt),
	}
	}
	}

	#[stable(feature = "rust1", since = "1.0.0")]
	impl error::Error for Error {
	#[allow(deprecated, deprecated_in_future)]
	fn description(&self) -> &str {
	match self.repr {
	Repr::Os(..) \| Repr::Simple(..) => self.kind().as_str(),
	Repr::SimpleMessage(_, &msg) => msg,
	Repr::Custom(ref c) => c.error.description(),
	}
	}

	#[allow(deprecated)]
	fn cause(&self) -> Option<&dyn error::Error> {
	match self.repr {
	Repr::Os(..) => None,
	Repr::Simple(..) => None,
	Repr::SimpleMessage(..) => None,
	Repr::Custom(ref c) => c.error.cause(),
	}
	}

	fn source(&self) -> Option<&(dyn error::Error + 'static)> {
	match self.repr {
	Repr::Os(..) => None,
	Repr::Simple(..) => None,
	Repr::SimpleMessage(..) => None,
	Repr::Custom(ref c) => c.error.source(),
	}
	}
	}

	fn _assert_error_is_sync_send() {
	fn _is_sync_send<T: Sync + Send>() {}
	_is_sync_send::<Error>();
	}