Struct polkadot_node_subsystem::gen::futures::io::Error

1.0.0 · source · 
pub struct Error { /* private fields */ }
Expand description

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.

Implementations§

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.

Note that this function allocates memory on the heap. If no extra payload is required, use the From conversion from ErrorKind.

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);

// creating an error without payload (and without memory allocation)
let eof_error = Error::from(ErrorKind::UnexpectedEof);
🔬This is a nightly-only experimental API. (io_error_other)

Creates a new I/O error from an arbitrary error payload.

This function is used to generically create I/O errors which do not originate from the OS itself. It is a shortcut for Error::new with ErrorKind::Other.

Examples
#![feature(io_error_other)]

use std::io::Error;

// errors can be created from strings
let custom_error = Error::other("oh no!");

// errors can also be created from other errors
let custom_error2 = Error::other(custom_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.

This should be called immediately after a call to a platform function, otherwise the state of the error value is indeterminate. In particular, other standard library functions may call platform functions that may (or may not) reset the error value even if they succeed.

Examples
use std::io::Error;

let os_error = Error::last_os_error();
println!("last OS error: {os_error:?}");

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);

On Windows:

use std::io;

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

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!"));
}

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!"));
}

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())));
}

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!"));
}
🔬This is a nightly-only experimental API. (io_error_downcast)

Attempt to downgrade the inner error to E if any.

If this Error was constructed via new then this function will attempt to perform downgrade on it, otherwise it will return Err.

If downgrade succeeds, it will return Ok, otherwise it will also return Err.

Examples
#![feature(io_error_downcast)]

use std::fmt;
use std::io;
use std::error::Error;

#[derive(Debug)]
enum E {
    Io(io::Error),
    SomeOtherVariant,
}

impl fmt::Display for E {
   // ...
}
impl Error for E {}

impl From<io::Error> for E {
    fn from(err: io::Error) -> E {
        err.downcast::<E>()
            .map(|b| *b)
            .unwrap_or_else(E::Io)
    }
}

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 "Uncategorized".
    print_error(Error::last_os_error());
    // Will print "AddrInUse".
    print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
}

Trait Implementations§

Formats the value using the given formatter. Read more
Formats the value using the given formatter. Read more
👎Deprecated since 1.42.0: use the Display impl or to_string()
Read more
👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting
The lower-level source of this error, if any. Read more
🔬This is a nightly-only experimental API. (error_generic_member_access)
Provides type based access to context intended for error reports. Read more
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.

Convert a serde_json::Error into an io::Error.

JSON syntax and data errors are turned into InvalidData IO errors. EOF errors are turned into UnexpectedEof IO errors.

use std::io;

enum MyError {
    Io(io::Error),
    Json(serde_json::Error),
}

impl From<serde_json::Error> for MyError {
    fn from(err: serde_json::Error) -> MyError {
        use serde_json::error::Category;
        match err.classify() {
            Category::Io => {
                MyError::Io(err.into())
            }
            Category::Syntax | Category::Data | Category::Eof => {
                MyError::Json(err)
            }
        }
    }
}
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.

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

Converts an ErrorKind into an Error.

This conversion creates 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}"));
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.

Converts a [alloc::ffi::NulError] into a Error.

Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
Convert from a value of T into an equivalent instance of Option<Self>. Read more
Consume self to return Some equivalent value of Option<T>. Read more
Converts self into T using Into<T>. Read more
Convert Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>. Box<dyn Any> can then be further downcast into Box<ConcreteType> where ConcreteType implements Trait. Read more
Convert Rc<Trait> (where Trait: Downcast) to Rc<Any>. Rc<Any> can then be further downcast into Rc<ConcreteType> where ConcreteType implements Trait. Read more
Convert &Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &Any’s vtable from &Trait’s. Read more
Convert &mut Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &mut Any’s vtable from &mut Trait’s. Read more
Convert Arc<Trait> (where Trait: Downcast) to Arc<Any>. Arc<Any> can then be further downcast into Arc<ConcreteType> where ConcreteType implements Trait. Read more
Causes self to use its Binary implementation when Debug-formatted. Read more
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Causes self to use its LowerExp implementation when Debug-formatted. Read more
Causes self to use its LowerHex implementation when Debug-formatted. Read more
Causes self to use its Octal implementation when Debug-formatted. Read more
Causes self to use its Pointer implementation when Debug-formatted. Read more
Causes self to use its UpperExp implementation when Debug-formatted. Read more
Causes self to use its UpperHex implementation when Debug-formatted. Read more
Formats each item in a sequence. Read more

Returns the argument unchanged.

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
Instruments this type with the current Span, returning an Instrumented wrapper. Read more
Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

Cast reference.
Cast reference.
Cast mutable reference.
Cast mutable reference.

Get a reference to the inner from the outer.

Get a mutable reference to the inner from the outer.

Pipes by value. This is generally the method you want to use. Read more
Borrows self and passes that borrow into the pipe function. Read more
Mutably borrows self and passes that borrow into the pipe function. Read more
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Mutably borrows self, then passes self.borrow_mut() into the pipe function. Read more
Borrows self, then passes self.as_ref() into the pipe function.
Mutably borrows self, then passes self.as_mut() into the pipe function. Read more
Borrows self, then passes self.deref() into the pipe function.
Mutably borrows self, then passes self.deref_mut() into the pipe function. Read more
The alignment of pointer.
The type for initializers.
Initializes a with the given initializer. Read more
Dereferences the given pointer. Read more
Mutably dereferences the given pointer. Read more
Drops the object pointed to by the given pointer. Read more
🔬This is a nightly-only experimental API. (provide_any)
Data providers should implement this method to provide all values they are able to provide by using demand. Read more
Should always be Self
Convert from a value of T into an equivalent instance of Self. Read more
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Mutable access to the AsMut<R> view of a value. Read more
Immutable access to the Deref::Target of a value. Read more
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Calls .tap() only in debug builds, and is erased in release builds.
Calls .tap_mut() only in debug builds, and is erased in release builds. Read more
Calls .tap_borrow() only in debug builds, and is erased in release builds. Read more
Calls .tap_borrow_mut() only in debug builds, and is erased in release builds. Read more
Calls .tap_ref() only in debug builds, and is erased in release builds. Read more
Calls .tap_ref_mut() only in debug builds, and is erased in release builds. Read more
Calls .tap_deref() only in debug builds, and is erased in release builds. Read more
Calls .tap_deref_mut() only in debug builds, and is erased in release builds. Read more
Converts the given value to a String. Read more
Attempts to convert self into T using TryInto<T>. Read more
The type returned in the event of a conversion error.
Performs the conversion.
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The counterpart to unchecked_from.
Consume self to return an equivalent value of T.
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