| use crate::error; |
| use crate::fmt; |
| use crate::result; |
| use crate::sys; |
| use crate::convert::From; |
| |
| /// A specialized [`Result`](../result/enum.Result.html) 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`]: ../io/index.html |
| /// [`io::Error`]: ../io/struct.Error.html |
| /// [`Result`]: ../result/enum.Result.html |
| /// |
| /// # 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`]: ../io/trait.Read.html |
| /// [`Write`]: ../io/trait.Write.html |
| /// [`Seek`]: ../io/trait.Seek.html |
| /// [`ErrorKind`]: enum.ErrorKind.html |
| #[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), |
| 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`]: struct.Error.html |
| #[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`]: #variant.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`]: ../../std/io/trait.Write.html#tymethod.write |
| /// [`Ok(0)`]: ../../std/io/type.Result.html |
| #[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. |
| #[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, |
| } |
| |
| 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", |
| } |
| } |
| } |
| |
| /// 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)); |
| /// ``` |
| /// |
| /// [`ErrorKind`]: ../../std/io/enum.ErrorKind.html |
| /// [`Error`]: ../../std/io/struct.Error.html |
| #[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, |
| })) |
| } |
| } |
| |
| /// 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")] |
| 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")] |
| 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`. |
| /// |
| /// # 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")] |
| pub fn raw_os_error(&self) -> Option<i32> { |
| match self.repr { |
| Repr::Os(i) => Some(i), |
| Repr::Custom(..) => None, |
| Repr::Simple(..) => 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`. |
| /// |
| /// # 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")] |
| pub fn get_ref(&self) -> Option<&(dyn error::Error+Send+Sync+'static)> { |
| match self.repr { |
| Repr::Os(..) => None, |
| Repr::Simple(..) => 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`. |
| /// |
| /// # 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 { |
| /// fn description(&self) -> &str { &self.v } |
| /// } |
| /// |
| /// 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")] |
| pub fn get_mut(&mut self) -> Option<&mut (dyn error::Error+Send+Sync+'static)> { |
| match self.repr { |
| Repr::Os(..) => None, |
| Repr::Simple(..) => 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`. |
| /// |
| /// # 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")] |
| pub fn into_inner(self) -> Option<Box<dyn error::Error+Send+Sync>> { |
| match self.repr { |
| Repr::Os(..) => None, |
| Repr::Simple(..) => 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 "No inner error". |
| /// print_error(Error::last_os_error()); |
| /// // Will print "Inner error: ...". |
| /// print_error(Error::new(ErrorKind::AddrInUse, "oh no!")); |
| /// } |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| 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, |
| } |
| } |
| } |
| |
| 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(), |
| } |
| } |
| } |
| |
| #[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()), |
| } |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl error::Error for Error { |
| fn description(&self) -> &str { |
| match self.repr { |
| Repr::Os(..) | Repr::Simple(..) => self.kind().as_str(), |
| 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::Custom(ref c) => c.error.cause(), |
| } |
| } |
| |
| fn source(&self) -> Option<&(dyn error::Error + 'static)> { |
| match self.repr { |
| Repr::Os(..) => None, |
| Repr::Simple(..) => 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 test { |
| use super::{Error, ErrorKind, Repr, Custom}; |
| use crate::error; |
| use crate::fmt; |
| use crate::sys::os::error_string; |
| use crate::sys::decode_error_kind; |
| |
| #[test] |
| fn test_debug_error() { |
| let code = 6; |
| let msg = error_string(code); |
| let kind = decode_error_kind(code); |
| let err = Error { |
| repr: Repr::Custom(box Custom { |
| kind: ErrorKind::InvalidInput, |
| error: box Error { |
| repr: super::Repr::Os(code) |
| }, |
| }) |
| }; |
| let expected = format!( |
| "Custom {{ \ |
| kind: InvalidInput, \ |
| error: Os {{ \ |
| code: {:?}, \ |
| kind: {:?}, \ |
| message: {:?} \ |
| }} \ |
| }}", |
| code, kind, msg |
| ); |
| assert_eq!(format!("{:?}", err), expected); |
| } |
| |
| #[test] |
| fn test_downcasting() { |
| #[derive(Debug)] |
| struct TestError; |
| |
| impl fmt::Display for TestError { |
| fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result { |
| Ok(()) |
| } |
| } |
| |
| impl error::Error for TestError { |
| fn description(&self) -> &str { |
| "asdf" |
| } |
| } |
| |
| // we have to call all of these UFCS style right now since method |
| // resolution won't implicitly drop the Send+Sync bounds |
| let mut err = Error::new(ErrorKind::Other, TestError); |
| assert!(err.get_ref().unwrap().is::<TestError>()); |
| assert_eq!("asdf", err.get_ref().unwrap().description()); |
| assert!(err.get_mut().unwrap().is::<TestError>()); |
| let extracted = err.into_inner().unwrap(); |
| extracted.downcast::<TestError>().unwrap(); |
| } |
| } |