1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
17 /// A specialized [`Result`](../result/enum.Result.html) type for I/O
20 /// This type is broadly used across [`std::io`] for any operation which may
23 /// This typedef is generally used to avoid writing out [`io::Error`] directly and
24 /// is otherwise a direct mapping to [`Result`].
26 /// While usual Rust style is to import types directly, aliases of [`Result`]
27 /// often are not, to make it easier to distinguish between them. [`Result`] is
28 /// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
29 /// will generally use `io::Result` instead of shadowing the prelude's import
30 /// of [`std::result::Result`][`Result`].
32 /// [`std::io`]: ../io/index.html
33 /// [`io::Error`]: ../io/struct.Error.html
34 /// [`Result`]: ../result/enum.Result.html
38 /// A convenience function that bubbles an `io::Result` to its caller:
43 /// fn get_string() -> io::Result<String> {
44 /// let mut buffer = String::new();
46 /// io::stdin().read_line(&mut buffer)?;
51 #[stable(feature = "rust1", since = "1.0.0")]
52 pub type Result<T> = result::Result<T, Error>;
54 /// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
55 /// associated traits.
57 /// Errors mostly originate from the underlying OS, but custom instances of
58 /// `Error` can be created with crafted error messages and a particular value of
61 /// [`Read`]: ../io/trait.Read.html
62 /// [`Write`]: ../io/trait.Write.html
63 /// [`Seek`]: ../io/trait.Seek.html
64 /// [`ErrorKind`]: enum.ErrorKind.html
66 #[stable(feature = "rust1", since = "1.0.0")]
80 error: Box<error::Error+Send+Sync>,
83 /// A list specifying general categories of I/O error.
85 /// This list is intended to grow over time and it is not recommended to
86 /// exhaustively match against it.
88 /// It is used with the [`io::Error`] type.
90 /// [`io::Error`]: struct.Error.html
91 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
92 #[stable(feature = "rust1", since = "1.0.0")]
95 /// An entity was not found, often a file.
96 #[stable(feature = "rust1", since = "1.0.0")]
98 /// The operation lacked the necessary privileges to complete.
99 #[stable(feature = "rust1", since = "1.0.0")]
101 /// The connection was refused by the remote server.
102 #[stable(feature = "rust1", since = "1.0.0")]
104 /// The connection was reset by the remote server.
105 #[stable(feature = "rust1", since = "1.0.0")]
107 /// The connection was aborted (terminated) by the remote server.
108 #[stable(feature = "rust1", since = "1.0.0")]
110 /// The network operation failed because it was not connected yet.
111 #[stable(feature = "rust1", since = "1.0.0")]
113 /// A socket address could not be bound because the address is already in
115 #[stable(feature = "rust1", since = "1.0.0")]
117 /// A nonexistent interface was requested or the requested address was not
119 #[stable(feature = "rust1", since = "1.0.0")]
121 /// The operation failed because a pipe was closed.
122 #[stable(feature = "rust1", since = "1.0.0")]
124 /// An entity already exists, often a file.
125 #[stable(feature = "rust1", since = "1.0.0")]
127 /// The operation needs to block to complete, but the blocking operation was
128 /// requested to not occur.
129 #[stable(feature = "rust1", since = "1.0.0")]
131 /// A parameter was incorrect.
132 #[stable(feature = "rust1", since = "1.0.0")]
134 /// Data not valid for the operation were encountered.
136 /// Unlike [`InvalidInput`], this typically means that the operation
137 /// parameters were valid, however the error was caused by malformed
140 /// For example, a function that reads a file into a string will error with
141 /// `InvalidData` if the file's contents are not valid UTF-8.
143 /// [`InvalidInput`]: #variant.InvalidInput
144 #[stable(feature = "io_invalid_data", since = "1.2.0")]
146 /// The I/O operation's timeout expired, causing it to be canceled.
147 #[stable(feature = "rust1", since = "1.0.0")]
149 /// An error returned when an operation could not be completed because a
150 /// call to [`write`] returned [`Ok(0)`].
152 /// This typically means that an operation could only succeed if it wrote a
153 /// particular number of bytes but only a smaller number of bytes could be
156 /// [`write`]: ../../std/io/trait.Write.html#tymethod.write
157 /// [`Ok(0)`]: ../../std/io/type.Result.html
158 #[stable(feature = "rust1", since = "1.0.0")]
160 /// This operation was interrupted.
162 /// Interrupted operations can typically be retried.
163 #[stable(feature = "rust1", since = "1.0.0")]
165 /// Any I/O error not part of this list.
166 #[stable(feature = "rust1", since = "1.0.0")]
169 /// An error returned when an operation could not be completed because an
170 /// "end of file" was reached prematurely.
172 /// This typically means that an operation could only succeed if it read a
173 /// particular number of bytes but only a smaller number of bytes could be
175 #[stable(feature = "read_exact", since = "1.6.0")]
178 /// A marker variant that tells the compiler that users of this enum cannot
179 /// match it exhaustively.
180 #[unstable(feature = "io_error_internals",
181 reason = "better expressed through extensible enums that this \
182 enum cannot be exhaustively matched against",
189 fn as_str(&self) -> &'static str {
191 ErrorKind::NotFound => "entity not found",
192 ErrorKind::PermissionDenied => "permission denied",
193 ErrorKind::ConnectionRefused => "connection refused",
194 ErrorKind::ConnectionReset => "connection reset",
195 ErrorKind::ConnectionAborted => "connection aborted",
196 ErrorKind::NotConnected => "not connected",
197 ErrorKind::AddrInUse => "address in use",
198 ErrorKind::AddrNotAvailable => "address not available",
199 ErrorKind::BrokenPipe => "broken pipe",
200 ErrorKind::AlreadyExists => "entity already exists",
201 ErrorKind::WouldBlock => "operation would block",
202 ErrorKind::InvalidInput => "invalid input parameter",
203 ErrorKind::InvalidData => "invalid data",
204 ErrorKind::TimedOut => "timed out",
205 ErrorKind::WriteZero => "write zero",
206 ErrorKind::Interrupted => "operation interrupted",
207 ErrorKind::Other => "other os error",
208 ErrorKind::UnexpectedEof => "unexpected end of file",
209 ErrorKind::__Nonexhaustive => unreachable!()
214 /// Intended for use for errors not exposed to the user, where allocating onto
215 /// the heap (for normal construction via Error::new) is too costly.
216 #[stable(feature = "io_error_from_errorkind", since = "1.14.0")]
217 impl From<ErrorKind> for Error {
219 fn from(kind: ErrorKind) -> Error {
221 repr: Repr::Simple(kind)
227 /// Creates a new I/O error from a known kind of error as well as an
228 /// arbitrary error payload.
230 /// This function is used to generically create I/O errors which do not
231 /// originate from the OS itself. The `error` argument is an arbitrary
232 /// payload which will be contained in this `Error`.
237 /// use std::io::{Error, ErrorKind};
239 /// // errors can be created from strings
240 /// let custom_error = Error::new(ErrorKind::Other, "oh no!");
242 /// // errors can also be created from other errors
243 /// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
245 #[stable(feature = "rust1", since = "1.0.0")]
246 pub fn new<E>(kind: ErrorKind, error: E) -> Error
247 where E: Into<Box<error::Error+Send+Sync>>
249 Self::_new(kind, error.into())
252 fn _new(kind: ErrorKind, error: Box<error::Error+Send+Sync>) -> Error {
254 repr: Repr::Custom(Box::new(Custom {
261 /// Returns an error representing the last OS error which occurred.
263 /// This function reads the value of `errno` for the target platform (e.g.
264 /// `GetLastError` on Windows) and will return a corresponding instance of
265 /// `Error` for the error code.
270 /// use std::io::Error;
272 /// println!("last OS error: {:?}", Error::last_os_error());
274 #[stable(feature = "rust1", since = "1.0.0")]
275 pub fn last_os_error() -> Error {
276 Error::from_raw_os_error(sys::os::errno() as i32)
279 /// Creates a new instance of an `Error` from a particular OS error code.
286 /// # if cfg!(target_os = "linux") {
289 /// let error = io::Error::from_raw_os_error(98);
290 /// assert_eq!(error.kind(), io::ErrorKind::AddrInUse);
297 /// # if cfg!(windows) {
300 /// let error = io::Error::from_raw_os_error(10048);
301 /// assert_eq!(error.kind(), io::ErrorKind::AddrInUse);
304 #[stable(feature = "rust1", since = "1.0.0")]
305 pub fn from_raw_os_error(code: i32) -> Error {
306 Error { repr: Repr::Os(code) }
309 /// Returns the OS error that this error represents (if any).
311 /// If this `Error` was constructed via `last_os_error` or
312 /// `from_raw_os_error`, then this function will return `Some`, otherwise
313 /// it will return `None`.
318 /// use std::io::{Error, ErrorKind};
320 /// fn print_os_error(err: &Error) {
321 /// if let Some(raw_os_err) = err.raw_os_error() {
322 /// println!("raw OS error: {:?}", raw_os_err);
324 /// println!("Not an OS error");
329 /// // Will print "raw OS error: ...".
330 /// print_os_error(&Error::last_os_error());
331 /// // Will print "Not an OS error".
332 /// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
335 #[stable(feature = "rust1", since = "1.0.0")]
336 pub fn raw_os_error(&self) -> Option<i32> {
338 Repr::Os(i) => Some(i),
339 Repr::Custom(..) => None,
340 Repr::Simple(..) => None,
344 /// Returns a reference to the inner error wrapped by this error (if any).
346 /// If this `Error` was constructed via `new` then this function will
347 /// return `Some`, otherwise it will return `None`.
352 /// use std::io::{Error, ErrorKind};
354 /// fn print_error(err: &Error) {
355 /// if let Some(inner_err) = err.get_ref() {
356 /// println!("Inner error: {:?}", inner_err);
358 /// println!("No inner error");
363 /// // Will print "No inner error".
364 /// print_error(&Error::last_os_error());
365 /// // Will print "Inner error: ...".
366 /// print_error(&Error::new(ErrorKind::Other, "oh no!"));
369 #[stable(feature = "io_error_inner", since = "1.3.0")]
370 pub fn get_ref(&self) -> Option<&(error::Error+Send+Sync+'static)> {
372 Repr::Os(..) => None,
373 Repr::Simple(..) => None,
374 Repr::Custom(ref c) => Some(&*c.error),
378 /// Returns a mutable reference to the inner error wrapped by this error
381 /// If this `Error` was constructed via `new` then this function will
382 /// return `Some`, otherwise it will return `None`.
387 /// use std::io::{Error, ErrorKind};
388 /// use std::{error, fmt};
389 /// use std::fmt::Display;
397 /// fn new() -> MyError {
399 /// v: "oh no!".to_string()
403 /// fn change_message(&mut self, new_message: &str) {
404 /// self.v = new_message.to_string();
408 /// impl error::Error for MyError {
409 /// fn description(&self) -> &str { &self.v }
412 /// impl Display for MyError {
413 /// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
414 /// write!(f, "MyError: {}", &self.v)
418 /// fn change_error(mut err: Error) -> Error {
419 /// if let Some(inner_err) = err.get_mut() {
420 /// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
425 /// fn print_error(err: &Error) {
426 /// if let Some(inner_err) = err.get_ref() {
427 /// println!("Inner error: {}", inner_err);
429 /// println!("No inner error");
434 /// // Will print "No inner error".
435 /// print_error(&change_error(Error::last_os_error()));
436 /// // Will print "Inner error: ...".
437 /// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
440 #[stable(feature = "io_error_inner", since = "1.3.0")]
441 pub fn get_mut(&mut self) -> Option<&mut (error::Error+Send+Sync+'static)> {
443 Repr::Os(..) => None,
444 Repr::Simple(..) => None,
445 Repr::Custom(ref mut c) => Some(&mut *c.error),
449 /// Consumes the `Error`, returning its inner error (if any).
451 /// If this `Error` was constructed via `new` then this function will
452 /// return `Some`, otherwise it will return `None`.
457 /// use std::io::{Error, ErrorKind};
459 /// fn print_error(err: Error) {
460 /// if let Some(inner_err) = err.into_inner() {
461 /// println!("Inner error: {}", inner_err);
463 /// println!("No inner error");
468 /// // Will print "No inner error".
469 /// print_error(Error::last_os_error());
470 /// // Will print "Inner error: ...".
471 /// print_error(Error::new(ErrorKind::Other, "oh no!"));
474 #[stable(feature = "io_error_inner", since = "1.3.0")]
475 pub fn into_inner(self) -> Option<Box<error::Error+Send+Sync>> {
477 Repr::Os(..) => None,
478 Repr::Simple(..) => None,
479 Repr::Custom(c) => Some(c.error)
483 /// Returns the corresponding `ErrorKind` for this error.
488 /// use std::io::{Error, ErrorKind};
490 /// fn print_error(err: Error) {
491 /// println!("{:?}", err.kind());
495 /// // Will print "No inner error".
496 /// print_error(Error::last_os_error());
497 /// // Will print "Inner error: ...".
498 /// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
501 #[stable(feature = "rust1", since = "1.0.0")]
502 pub fn kind(&self) -> ErrorKind {
504 Repr::Os(code) => sys::decode_error_kind(code),
505 Repr::Custom(ref c) => c.kind,
506 Repr::Simple(kind) => kind,
511 impl fmt::Debug for Repr {
512 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
514 Repr::Os(ref code) =>
515 fmt.debug_struct("Os").field("code", code)
516 .field("message", &sys::os::error_string(*code)).finish(),
517 Repr::Custom(ref c) => fmt.debug_tuple("Custom").field(c).finish(),
518 Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
523 #[stable(feature = "rust1", since = "1.0.0")]
524 impl fmt::Display for Error {
525 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
528 let detail = sys::os::error_string(code);
529 write!(fmt, "{} (os error {})", detail, code)
531 Repr::Custom(ref c) => c.error.fmt(fmt),
532 Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
537 #[stable(feature = "rust1", since = "1.0.0")]
538 impl error::Error for Error {
539 fn description(&self) -> &str {
541 Repr::Os(..) | Repr::Simple(..) => self.kind().as_str(),
542 Repr::Custom(ref c) => c.error.description(),
546 fn cause(&self) -> Option<&error::Error> {
548 Repr::Os(..) => None,
549 Repr::Simple(..) => None,
550 Repr::Custom(ref c) => c.error.cause(),
555 fn _assert_error_is_sync_send() {
556 fn _is_sync_send<T: Sync+Send>() {}
557 _is_sync_send::<Error>();
562 use super::{Error, ErrorKind};
565 use sys::os::error_string;
568 fn test_debug_error() {
570 let msg = error_string(code);
571 let err = Error { repr: super::Repr::Os(code) };
572 let expected = format!("Error {{ repr: Os {{ code: {:?}, message: {:?} }} }}", code, msg);
573 assert_eq!(format!("{:?}", err), expected);
577 fn test_downcasting() {
581 impl fmt::Display for TestError {
582 fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
587 impl error::Error for TestError {
588 fn description(&self) -> &str {
593 // we have to call all of these UFCS style right now since method
594 // resolution won't implicitly drop the Send+Sync bounds
595 let mut err = Error::new(ErrorKind::Other, TestError);
596 assert!(err.get_ref().unwrap().is::<TestError>());
597 assert_eq!("asdf", err.get_ref().unwrap().description());
598 assert!(err.get_mut().unwrap().is::<TestError>());
599 let extracted = err.into_inner().unwrap();
600 extracted.downcast::<TestError>().unwrap();