Struct Unspecified

pub struct Unspecified;

An error with absolutely no details.

aws-lc-rs uses this unit type as the error type in most of its results because (a) usually the specific reasons for a failure are obvious or are not useful to know, and/or (b) providing more details about a failure might provide a dangerous side channel, and/or (c) it greatly simplifies the error handling logic.

Result<T, aws_lc_rs::error::Unspecified> is mostly equivalent to Result<T, ()>. However, aws_lc_rs::error::Unspecified implements std::error::Error and users can implement From<error::Unspecified> to map this to their own error types, as described in “Error Handling” in the Rust Book:

use aws_lc_rs::rand::{self, SecureRandom};

enum Error {
    CryptoError,

    IOError(std::io::Error),
    // [...]
}

impl From<aws_lc_rs::error::Unspecified> for Error {
    fn from(_: aws_lc_rs::error::Unspecified) -> Self {
        Error::CryptoError
    }
}

fn eight_random_bytes() -> Result<[u8; 8], Error> {
    let rng = rand::SystemRandom::new();
    let mut bytes = [0; 8];

    // The `From<aws_lc_rs::error::Unspecified>` implementation above makes this
    // equivalent to
    // `rng.fill(&mut bytes).map_err(|_| Error::CryptoError)?`.
    rng.fill(&mut bytes)?;

    Ok(bytes)
}

assert!(eight_random_bytes().is_ok());

Experience with using and implementing other crypto libraries like has shown that sophisticated error reporting facilities often cause significant bugs themselves, both within the crypto library and within users of the crypto library. This approach attempts to minimize complexity in the hopes of avoiding such problems. In some cases, this approach may be too extreme, and it may be important for an operation to provide some details about the cause of a failure. Users of aws-lc-rs are encouraged to report such cases so that they can be addressed individually.

Trait Implementations

impl Clone for Unspecified

fn clone(&self) -> Unspecified

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Unspecified

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Display for Unspecified

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Error for Unspecified

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<()> for Unspecified

fn from(_: ()) -> Unspecified

Converts to this type from the input type.

impl From<EndOfInput> for Unspecified

fn from(_: EndOfInput) -> Unspecified

Converts to this type from the input type.

impl From<KeyRejected> for Unspecified

fn from(_: KeyRejected) -> Unspecified

Converts to this type from the input type.

impl From<TryFromIntError> for Unspecified

fn from(_: TryFromIntError) -> Unspecified

Converts to this type from the input type.

impl From<TryFromSliceError> for Unspecified

fn from(_: TryFromSliceError) -> Unspecified

Converts to this type from the input type.

impl From<Unspecified> for ()

fn from(_: Unspecified)

Converts to this type from the input type.

impl From<Unspecified> for KeyRejected

fn from(_: Unspecified) -> KeyRejected

Converts to this type from the input type.

impl PartialEq for Unspecified

fn eq(&self, other: &Unspecified) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Unspecified

impl Eq for Unspecified

impl StructuralPartialEq for Unspecified