1.0.0[][src]Struct std::io::Error

pub struct Error { /* fields omitted */ }

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.

Methods

impl Error[src]

pub fn new<E>(kind: ErrorKind, error: E) -> Error where
    E: Into<Box<dyn Error + Send + Sync>>, 
[src]

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);Run

pub fn last_os_error() -> Error[src]

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());Run

pub fn from_raw_os_error(code: i32) -> Error[src]

Creates a new instance of an Error from a particular OS error code.

Examples

On Linux:

use std::io;

let error = io::Error::from_raw_os_error(22);
assert_eq!(error.kind(), io::ErrorKind::InvalidInput);Run

On Windows:

use std::io;

let error = io::Error::from_raw_os_error(10022);
assert_eq!(error.kind(), io::ErrorKind::InvalidInput);Run

pub fn raw_os_error(&self) -> Option<i32>[src]

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!"));
}Run

pub fn get_ref(&self) -> Option<&(dyn Error + Send + Sync + 'static)>1.3.0[src]

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!"));
}Run

pub fn get_mut(&mut self) -> Option<&mut (dyn Error + Send + Sync + 'static)>1.3.0[src]

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())));
}Run

pub fn into_inner(self) -> Option<Box<dyn Error + Send + Sync>>1.3.0[src]

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!"));
}Run

pub fn kind(&self) -> ErrorKind[src]

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!"));
}Run

Trait Implementations

impl Error for Error[src]

impl From<NulError> for Error[src]

fn from(_: NulError) -> Error[src]

Converts a NulError into a io::Error.

impl<W> From<IntoInnerError<W>> for Error[src]

impl From<ErrorKind> for Error1.14.0[src]

Intended for use for errors not exposed to the user, where allocating onto the heap (for normal construction via Error::new) is too costly.

fn from(kind: ErrorKind) -> Error[src]

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));Run

impl Debug for Error[src]

impl Display for Error[src]

Auto Trait Implementations

impl !UnwindSafe for Error

impl !RefUnwindSafe for Error

impl Unpin for Error

impl Send for Error

impl Sync for Error

Blanket Implementations

impl<T> From<T> for T[src]

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = !

The type returned in the event of a conversion error.

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<T> ToString for T where
    T: Display + ?Sized
[src]