Type Alias AlignedTryCastError

pub type AlignedTryCastError<Src, Dst: ?Sized + TryFromBytes> = ConvertError<Infallible, SizeError<Src, Dst>, ValidityError<Src, Dst>>;

The error type of well-aligned, fallible casts.

This is like TryCastError, but for casts that are always well-aligned. It is identical to TryCastError, except that its alignment error is Infallible.

As of this writing, none of zerocopy’s API produces this error directly. However, it is useful since it permits users to infallibly discard alignment errors when they can prove statically that alignment errors are impossible.

Examples

use core::convert::Infallible;
use zerocopy::*;

#[derive(TryFromBytes, KnownLayout, Unaligned, Immutable)]
#[repr(C, packed)]
struct Bools {
    one: bool,
    two: bool,
    many: [bool],
}

impl Bools {
    fn parse(bytes: &[u8]) -> Result<&Bools, AlignedTryCastError<&[u8], Bools>> {
        // Since `Bools: Unaligned`, we can infallibly discard
        // the alignment error.
        Bools::try_ref_from_bytes(bytes).map_err(Into::into)
    }
}

Aliased Type

enum AlignedTryCastError<Src, Dst: ?Sized + TryFromBytes> {
    Alignment(Infallible),
    Size(SizeError<Src, Dst>),
    Validity(ValidityError<Src, Dst>),
}

Variants

Alignment(Infallible)

The conversion source was improperly aligned.

Size(SizeError<Src, Dst>)

The conversion source was of incorrect size.

Validity(ValidityError<Src, Dst>)

The conversion source contained invalid data.

Implementations

impl<Src, Dst: ?Sized + TryFromBytes> ConvertError<Infallible, SizeError<Src, Dst>, ValidityError<Src, Dst>>

pub fn into_src(self) -> Src

Produces the source underlying the failed conversion.

pub fn map_src<NewSrc>( self, f: impl FnOnce(Src) -> NewSrc, ) -> TryReadError<NewSrc, Dst>

Maps the source value associated with the conversion error.

This can help mitigate issues with Send, Sync and 'static bounds.

Examples

use core::num::NonZeroU32;
use zerocopy::*;

let source: [u8; 3] = [0, 0, 0];

// Try to read a `NonZeroU32` from `source`.
let maybe_u32: Result<NonZeroU32, TryReadError<&[u8], NonZeroU32>>
    = NonZeroU32::try_read_from_bytes(&source[..]);

// Map the error's source to its size.
let maybe_u32: Result<NonZeroU32, TryReadError<usize, NonZeroU32>> =
    maybe_u32.map_err(|err| {
        err.map_src(|src| src.len())
    });

Trait Implementations

impl<A: Debug, S: Debug, V: Debug> Debug for ConvertError<A, S, V>

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

Formats the value using the given formatter.

impl<A: Display, S: Display, V: Display> Display for ConvertError<A, S, V>

Produces a human-readable error message.

The message differs between debug and release builds. When debug_assertions are enabled, this message is verbose and includes potentially sensitive information.

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

Formats the value using the given formatter.

impl<A, S, V> Error for ConvertError<A, S, V>

where A: Display + Debug, S: Display + Debug, V: Display + Debug,

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

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

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 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<Src, Dst: ?Sized + Unaligned, S, V> From<ConvertError<AlignmentError<Src, Dst>, S, V>> for ConvertError<Infallible, S, V>

fn from( err: ConvertError<AlignmentError<Src, Dst>, S, V>, ) -> ConvertError<Infallible, S, V>

Infallibly discards the alignment error from this ConvertError since Dst is unaligned.

Since Dst: Unaligned, it is impossible to encounter an alignment error. This method permits discarding that alignment error infallibly and replacing it with Infallible.

Examples

use core::convert::Infallible;
use zerocopy::*;

#[derive(TryFromBytes, KnownLayout, Unaligned, Immutable)]
#[repr(C, packed)]
struct Bools {
    one: bool,
    two: bool,
    many: [bool],
}

impl Bools {
    fn parse(bytes: &[u8]) -> Result<&Bools, AlignedTryCastError<&[u8], Bools>> {
        // Since `Bools: Unaligned`, we can infallibly discard
        // the alignment error.
        Bools::try_ref_from_bytes(bytes).map_err(Into::into)
    }
}

impl<Src, Dst: ?Sized, A, V> From<SizeError<Src, Dst>> for ConvertError<A, SizeError<Src, Dst>, V>

fn from(err: SizeError<Src, Dst>) -> Self

Converts to this type from the input type.

impl<Src, Dst: ?Sized + TryFromBytes, A, S> From<ValidityError<Src, Dst>> for ConvertError<A, S, ValidityError<Src, Dst>>

fn from(err: ValidityError<Src, Dst>) -> Self

Converts to this type from the input type.

impl<A: PartialEq, S: PartialEq, V: PartialEq> PartialEq for ConvertError<A, S, V>

fn eq(&self, other: &ConvertError<A, S, V>) -> 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<A: Eq, S: Eq, V: Eq> Eq for ConvertError<A, S, V>

impl<A, S, V> StructuralPartialEq for ConvertError<A, S, V>