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Diffstat (limited to 'library/std/src/io/error.rs')
| -rw-r--r-- | library/std/src/io/error.rs | 628 |
1 files changed, 628 insertions, 0 deletions
diff --git a/library/std/src/io/error.rs b/library/std/src/io/error.rs new file mode 100644 index 00000000000..f7248e7547e --- /dev/null +++ b/library/std/src/io/error.rs @@ -0,0 +1,628 @@ +use crate::convert::From; +use crate::error; +use crate::fmt; +use crate::result; +use crate::sys; + +/// 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. + /// + /// 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, +} + +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 {} + /// + /// 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 "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")] + 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 { + #[allow(deprecated, deprecated_in_future)] + 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::{Custom, Error, ErrorKind, Repr}; + use crate::error; + use crate::fmt; + use crate::sys::decode_error_kind; + use crate::sys::os::error_string; + + #[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, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.write_str("asdf") + } + } + + impl error::Error for TestError {} + + // 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().to_string()); + assert!(err.get_mut().unwrap().is::<TestError>()); + let extracted = err.into_inner().unwrap(); + extracted.downcast::<TestError>().unwrap(); + } +} |