blob: f7248e7547e27620b766649e48a7514a7a1ad158 [file] [log] [blame]
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();
}
}