912 lines
30 KiB
Rust
912 lines
30 KiB
Rust
use crate::chain::Chain;
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use crate::ptr::{MutPtr, OwnedPtr, RefPtr};
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use crate::EyreHandler;
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use crate::{Report, StdError};
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use core::any::TypeId;
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use core::fmt::{self, Debug, Display};
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use core::mem::{self, ManuallyDrop};
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use core::ptr::{self, NonNull};
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use core::ops::{Deref, DerefMut};
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impl Report {
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/// Create a new error object from any error type.
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///
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/// The error type must be threadsafe and `'static`, so that the `Report`
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/// will be as well.
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///
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/// If the error type does not provide a backtrace, a backtrace will be
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/// created here to ensure that a backtrace exists.
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#[cfg_attr(track_caller, track_caller)]
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pub fn new<E>(error: E) -> Self
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where
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E: StdError + Send + Sync + 'static,
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{
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Report::from_std(error)
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}
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/// Create a new error object from a printable error message.
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///
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/// If the argument implements std::error::Error, prefer `Report::new`
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/// instead which preserves the underlying error's cause chain and
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/// backtrace. If the argument may or may not implement std::error::Error
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/// now or in the future, use `eyre!(err)` which handles either way
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/// correctly.
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///
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/// `Report::msg("...")` is equivalent to `eyre!("...")` but occasionally
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/// convenient in places where a function is preferable over a macro, such
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/// as iterator or stream combinators:
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///
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/// ```
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/// # mod ffi {
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/// # pub struct Input;
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/// # pub struct Output;
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/// # pub async fn do_some_work(_: Input) -> Result<Output, &'static str> {
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/// # unimplemented!()
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/// # }
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/// # }
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/// #
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/// # use ffi::{Input, Output};
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/// #
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/// use eyre::{Report, Result};
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/// use futures::stream::{Stream, StreamExt, TryStreamExt};
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///
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/// async fn demo<S>(stream: S) -> Result<Vec<Output>>
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/// where
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/// S: Stream<Item = Input>,
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/// {
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/// stream
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/// .then(ffi::do_some_work) // returns Result<Output, &str>
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/// .map_err(Report::msg)
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/// .try_collect()
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/// .await
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/// }
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/// ```
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#[cfg_attr(track_caller, track_caller)]
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pub fn msg<M>(message: M) -> Self
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where
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M: Display + Debug + Send + Sync + 'static,
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{
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Report::from_adhoc(message)
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}
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#[cfg_attr(track_caller, track_caller)]
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/// Creates a new error from an implementor of [`std::error::Error`]
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pub(crate) fn from_std<E>(error: E) -> Self
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where
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E: StdError + Send + Sync + 'static,
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{
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let vtable = &ErrorVTable {
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object_drop: object_drop::<E>,
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object_ref: object_ref::<E>,
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object_mut: object_mut::<E>,
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object_boxed: object_boxed::<E>,
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object_downcast: object_downcast::<E>,
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object_downcast_mut: object_downcast_mut::<E>,
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object_drop_rest: object_drop_front::<E>,
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};
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// Safety: passing vtable that operates on the right type E.
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let handler = Some(crate::capture_handler(&error));
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unsafe { Report::construct(error, vtable, handler) }
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}
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#[cfg_attr(track_caller, track_caller)]
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pub(crate) fn from_adhoc<M>(message: M) -> Self
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where
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M: Display + Debug + Send + Sync + 'static,
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{
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use crate::wrapper::MessageError;
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let error: MessageError<M> = MessageError(message);
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let vtable = &ErrorVTable {
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object_drop: object_drop::<MessageError<M>>,
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object_ref: object_ref::<MessageError<M>>,
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object_mut: object_mut::<MessageError<M>>,
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object_boxed: object_boxed::<MessageError<M>>,
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object_downcast: object_downcast::<M>,
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object_downcast_mut: object_downcast_mut::<M>,
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object_drop_rest: object_drop_front::<M>,
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};
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// Safety: MessageError is repr(transparent) so it is okay for the
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// vtable to allow casting the MessageError<M> to M.
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let handler = Some(crate::capture_handler(&error));
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unsafe { Report::construct(error, vtable, handler) }
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}
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#[cfg_attr(track_caller, track_caller)]
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pub(crate) fn from_display<M>(message: M) -> Self
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where
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M: Display + Send + Sync + 'static,
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{
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use crate::wrapper::{DisplayError, NoneError};
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let error: DisplayError<M> = DisplayError(message);
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let vtable = &ErrorVTable {
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object_drop: object_drop::<DisplayError<M>>,
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object_ref: object_ref::<DisplayError<M>>,
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object_mut: object_mut::<DisplayError<M>>,
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object_boxed: object_boxed::<DisplayError<M>>,
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object_downcast: object_downcast::<M>,
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object_downcast_mut: object_downcast_mut::<M>,
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object_drop_rest: object_drop_front::<M>,
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};
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// Safety: DisplayError is repr(transparent) so it is okay for the
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// vtable to allow casting the DisplayError<M> to M.
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let handler = Some(crate::capture_handler(&NoneError));
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unsafe { Report::construct(error, vtable, handler) }
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}
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#[cfg_attr(track_caller, track_caller)]
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pub(crate) fn from_msg<D, E>(msg: D, error: E) -> Self
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where
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D: Display + Send + Sync + 'static,
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E: StdError + Send + Sync + 'static,
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{
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let error: ContextError<D, E> = ContextError { msg, error };
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let vtable = &ErrorVTable {
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object_drop: object_drop::<ContextError<D, E>>,
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object_ref: object_ref::<ContextError<D, E>>,
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object_mut: object_mut::<ContextError<D, E>>,
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object_boxed: object_boxed::<ContextError<D, E>>,
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object_downcast: context_downcast::<D, E>,
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object_downcast_mut: context_downcast_mut::<D, E>,
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object_drop_rest: context_drop_rest::<D, E>,
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};
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// Safety: passing vtable that operates on the right type.
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let handler = Some(crate::capture_handler(&error));
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unsafe { Report::construct(error, vtable, handler) }
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}
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#[cfg_attr(track_caller, track_caller)]
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pub(crate) fn from_boxed(error: Box<dyn StdError + Send + Sync>) -> Self {
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use crate::wrapper::BoxedError;
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let error = BoxedError(error);
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let handler = Some(crate::capture_handler(&error));
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let vtable = &ErrorVTable {
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object_drop: object_drop::<BoxedError>,
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object_ref: object_ref::<BoxedError>,
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object_mut: object_mut::<BoxedError>,
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object_boxed: object_boxed::<BoxedError>,
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object_downcast: object_downcast::<Box<dyn StdError + Send + Sync>>,
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object_downcast_mut: object_downcast_mut::<Box<dyn StdError + Send + Sync>>,
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object_drop_rest: object_drop_front::<Box<dyn StdError + Send + Sync>>,
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};
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// Safety: BoxedError is repr(transparent) so it is okay for the vtable
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// to allow casting to Box<dyn StdError + Send + Sync>.
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unsafe { Report::construct(error, vtable, handler) }
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}
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// Takes backtrace as argument rather than capturing it here so that the
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// user sees one fewer layer of wrapping noise in the backtrace.
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//
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// Unsafe because the given vtable must have sensible behavior on the error
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// value of type E.
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unsafe fn construct<E>(
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error: E,
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vtable: &'static ErrorVTable,
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handler: Option<Box<dyn EyreHandler>>,
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) -> Self
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where
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E: StdError + Send + Sync + 'static,
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{
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let inner = ErrorImpl {
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header: ErrorHeader { vtable, handler },
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_object: error,
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};
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// Construct a new owned allocation through a raw pointer
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//
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// This does not keep the allocation around as a `Box` which would invalidate an
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// references when moved
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let ptr = OwnedPtr::<ErrorImpl<E>>::new(inner);
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// Safety: the type
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let ptr = ptr.cast::<ErrorImpl<()>>();
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Report { inner: ptr }
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}
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/// Create a new error from an error message to wrap the existing error.
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///
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/// For attaching a higher level error message to a `Result` as it is propagated, the
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/// [`WrapErr`][crate::WrapErr] extension trait may be more convenient than this function.
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///
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/// The primary reason to use `error.wrap_err(...)` instead of `result.wrap_err(...)` via the
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/// `WrapErr` trait would be if the message needs to depend on some data held by the underlying
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/// error:
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///
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/// ```
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/// # use std::fmt::{self, Debug, Display};
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/// #
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/// # type T = ();
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/// #
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/// # impl std::error::Error for ParseError {}
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/// # impl Debug for ParseError {
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/// # fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
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/// # unimplemented!()
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/// # }
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/// # }
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/// # impl Display for ParseError {
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/// # fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
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/// # unimplemented!()
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/// # }
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/// # }
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/// #
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/// use eyre::Result;
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/// use std::fs::File;
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/// use std::path::Path;
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///
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/// struct ParseError {
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/// line: usize,
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/// column: usize,
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/// }
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///
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/// fn parse_impl(file: File) -> Result<T, ParseError> {
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/// # const IGNORE: &str = stringify! {
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/// ...
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/// # };
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/// # unimplemented!()
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/// }
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///
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/// pub fn parse(path: impl AsRef<Path>) -> Result<T> {
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/// let file = File::open(&path)?;
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/// parse_impl(file).map_err(|error| {
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/// let message = format!(
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/// "only the first {} lines of {} are valid",
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/// error.line, path.as_ref().display(),
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/// );
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/// eyre::Report::new(error).wrap_err(message)
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/// })
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/// }
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/// ```
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pub fn wrap_err<D>(mut self, msg: D) -> Self
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where
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D: Display + Send + Sync + 'static,
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{
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// Safety: this access a `ErrorImpl<unknown>` as a valid reference to a `ErrorImpl<()>`
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//
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// As the generic is at the end of the struct and the struct is `repr(C)` this reference
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// will be within bounds of the original pointer, and the field will have the same offset
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let handler = header_mut(self.inner.as_mut()).handler.take();
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let error: ContextError<D, Report> = ContextError { msg, error: self };
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let vtable = &ErrorVTable {
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object_drop: object_drop::<ContextError<D, Report>>,
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object_ref: object_ref::<ContextError<D, Report>>,
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object_mut: object_mut::<ContextError<D, Report>>,
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object_boxed: object_boxed::<ContextError<D, Report>>,
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object_downcast: context_chain_downcast::<D>,
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object_downcast_mut: context_chain_downcast_mut::<D>,
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object_drop_rest: context_chain_drop_rest::<D>,
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};
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// Safety: passing vtable that operates on the right type.
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unsafe { Report::construct(error, vtable, handler) }
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}
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/// Access the vtable for the current error object.
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fn vtable(&self) -> &'static ErrorVTable {
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header(self.inner.as_ref()).vtable
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}
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/// An iterator of the chain of source errors contained by this Report.
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///
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/// This iterator will visit every error in the cause chain of this error
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/// object, beginning with the error that this error object was created
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/// from.
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///
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/// # Example
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///
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/// ```
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/// use eyre::Report;
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/// use std::io;
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///
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/// pub fn underlying_io_error_kind(error: &Report) -> Option<io::ErrorKind> {
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/// for cause in error.chain() {
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/// if let Some(io_error) = cause.downcast_ref::<io::Error>() {
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/// return Some(io_error.kind());
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/// }
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/// }
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/// None
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/// }
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/// ```
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pub fn chain(&self) -> Chain<'_> {
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ErrorImpl::chain(self.inner.as_ref())
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}
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/// The lowest level cause of this error — this error's cause's
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/// cause's cause etc.
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///
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/// The root cause is the last error in the iterator produced by
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/// [`chain()`][Report::chain].
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pub fn root_cause(&self) -> &(dyn StdError + 'static) {
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let mut chain = self.chain();
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let mut root_cause = chain.next().unwrap();
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for cause in chain {
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root_cause = cause;
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}
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root_cause
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}
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/// Returns true if `E` is the type held by this error object.
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///
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/// For errors constructed from messages, this method returns true if `E` matches the type of
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/// the message `D` **or** the type of the error on which the message has been attached. For
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/// details about the interaction between message and downcasting, [see here].
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///
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/// [see here]: trait.WrapErr.html#effect-on-downcasting
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pub fn is<E>(&self) -> bool
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where
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E: Display + Debug + Send + Sync + 'static,
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{
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self.downcast_ref::<E>().is_some()
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}
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/// Attempt to downcast the error object to a concrete type.
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pub fn downcast<E>(self) -> Result<E, Self>
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where
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E: Display + Debug + Send + Sync + 'static,
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{
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let target = TypeId::of::<E>();
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unsafe {
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// Use vtable to find NonNull<()> which points to a value of type E
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// somewhere inside the data structure.
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let addr = match (self.vtable().object_downcast)(self.inner.as_ref(), target) {
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Some(addr) => addr,
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None => return Err(self),
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};
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// Prepare to read E out of the data structure. We'll drop the rest
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// of the data structure separately so that E is not dropped.
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let outer = ManuallyDrop::new(self);
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// Read E from where the vtable found it.
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let error = ptr::read(addr.cast::<E>().as_ptr());
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// Read Box<ErrorImpl<()>> from self. Can't move it out because
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// Report has a Drop impl which we want to not run.
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let inner = ptr::read(&outer.inner);
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// Drop rest of the data structure outside of E.
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(outer.vtable().object_drop_rest)(inner, target);
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Ok(error)
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}
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}
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/// Downcast this error object by reference.
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///
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/// # Example
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///
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/// ```
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/// # use eyre::{Report, eyre};
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/// # use std::fmt::{self, Display};
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/// # use std::task::Poll;
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/// #
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/// # #[derive(Debug)]
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/// # enum DataStoreError {
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/// # Censored(()),
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/// # }
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/// #
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/// # impl Display for DataStoreError {
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/// # fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
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/// # unimplemented!()
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/// # }
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/// # }
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/// #
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/// # impl std::error::Error for DataStoreError {}
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/// #
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/// # const REDACTED_CONTENT: () = ();
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/// #
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/// # #[cfg(not(feature = "auto-install"))]
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/// # eyre::set_hook(Box::new(eyre::DefaultHandler::default_with)).unwrap();
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/// #
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/// # let error: Report = eyre!("...");
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/// # let root_cause = &error;
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/// #
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/// # let ret =
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/// // If the error was caused by redaction, then return a tombstone instead
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/// // of the content.
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/// match root_cause.downcast_ref::<DataStoreError>() {
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/// Some(DataStoreError::Censored(_)) => Ok(Poll::Ready(REDACTED_CONTENT)),
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/// None => Err(error),
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/// }
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/// # ;
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/// ```
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pub fn downcast_ref<E>(&self) -> Option<&E>
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where
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E: Display + Debug + Send + Sync + 'static,
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{
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let target = TypeId::of::<E>();
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unsafe {
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// Use vtable to find NonNull<()> which points to a value of type E
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// somewhere inside the data structure.
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let addr = (self.vtable().object_downcast)(self.inner.as_ref(), target)?;
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Some(addr.cast::<E>().as_ref())
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}
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}
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/// Downcast this error object by mutable reference.
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pub fn downcast_mut<E>(&mut self) -> Option<&mut E>
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where
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E: Display + Debug + Send + Sync + 'static,
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{
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let target = TypeId::of::<E>();
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unsafe {
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// Use vtable to find NonNull<()> which points to a value of type E
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// somewhere inside the data structure.
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let addr = (self.vtable().object_downcast_mut)(self.inner.as_mut(), target)?;
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Some(addr.cast::<E>().as_mut())
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}
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}
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/// Get a reference to the Handler for this Report.
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pub fn handler(&self) -> &dyn EyreHandler {
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header(self.inner.as_ref())
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.handler
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.as_ref()
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.unwrap()
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.as_ref()
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}
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/// Get a mutable reference to the Handler for this Report.
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pub fn handler_mut(&mut self) -> &mut dyn EyreHandler {
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header_mut(self.inner.as_mut())
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.handler
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.as_mut()
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.unwrap()
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.as_mut()
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}
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|
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/// Get a reference to the Handler for this Report.
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#[doc(hidden)]
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pub fn context(&self) -> &dyn EyreHandler {
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header(self.inner.as_ref())
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.handler
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.as_ref()
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.unwrap()
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.as_ref()
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}
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|
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/// Get a mutable reference to the Handler for this Report.
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#[doc(hidden)]
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pub fn context_mut(&mut self) -> &mut dyn EyreHandler {
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header_mut(self.inner.as_mut())
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.handler
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.as_mut()
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.unwrap()
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.as_mut()
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}
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}
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|
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impl<E> From<E> for Report
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|
where
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E: StdError + Send + Sync + 'static,
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{
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#[cfg_attr(track_caller, track_caller)]
|
|
fn from(error: E) -> Self {
|
|
Report::from_std(error)
|
|
}
|
|
}
|
|
|
|
impl Deref for Report {
|
|
type Target = dyn StdError + Send + Sync + 'static;
|
|
|
|
fn deref(&self) -> &Self::Target {
|
|
ErrorImpl::error(self.inner.as_ref())
|
|
}
|
|
}
|
|
|
|
impl DerefMut for Report {
|
|
fn deref_mut(&mut self) -> &mut Self::Target {
|
|
ErrorImpl::error_mut(self.inner.as_mut())
|
|
}
|
|
}
|
|
|
|
impl Display for Report {
|
|
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
ErrorImpl::display(self.inner.as_ref(), formatter)
|
|
}
|
|
}
|
|
|
|
impl Debug for Report {
|
|
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
ErrorImpl::debug(self.inner.as_ref(), formatter)
|
|
}
|
|
}
|
|
|
|
impl Drop for Report {
|
|
fn drop(&mut self) {
|
|
unsafe {
|
|
// Read Box<ErrorImpl<()>> from self.
|
|
(self.vtable().object_drop)(self.inner);
|
|
}
|
|
}
|
|
}
|
|
|
|
struct ErrorVTable {
|
|
object_drop: unsafe fn(OwnedPtr<ErrorImpl<()>>),
|
|
object_ref: unsafe fn(RefPtr<'_, ErrorImpl<()>>) -> &(dyn StdError + Send + Sync + 'static),
|
|
object_mut: unsafe fn(MutPtr<'_, ErrorImpl<()>>) -> &mut (dyn StdError + Send + Sync + 'static),
|
|
#[allow(clippy::type_complexity)]
|
|
object_boxed: unsafe fn(OwnedPtr<ErrorImpl<()>>) -> Box<dyn StdError + Send + Sync + 'static>,
|
|
object_downcast: unsafe fn(RefPtr<'_, ErrorImpl<()>>, TypeId) -> Option<NonNull<()>>,
|
|
object_downcast_mut: unsafe fn(MutPtr<'_, ErrorImpl<()>>, TypeId) -> Option<NonNull<()>>,
|
|
object_drop_rest: unsafe fn(OwnedPtr<ErrorImpl<()>>, TypeId),
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<E>.
|
|
unsafe fn object_drop<E>(e: OwnedPtr<ErrorImpl<()>>) {
|
|
// Cast to a context type and drop the Box allocation.
|
|
let unerased = unsafe { e.cast::<ErrorImpl<E>>().into_box() };
|
|
drop(unerased);
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<E>.
|
|
unsafe fn object_drop_front<E>(e: OwnedPtr<ErrorImpl<()>>, target: TypeId) {
|
|
// Drop the fields of ErrorImpl other than E as well as the Box allocation,
|
|
// without dropping E itself. This is used by downcast after doing a
|
|
// ptr::read to take ownership of the E.
|
|
let _ = target;
|
|
// Note: This must not use `mem::transmute` because it tries to reborrow the `Unique`
|
|
// contained in `Box`, which must not be done. In practice this probably won't make any
|
|
// difference by now, but technically it's unsound.
|
|
// see: https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.m
|
|
let unerased = unsafe { e.cast::<ErrorImpl<E>>().into_box() };
|
|
|
|
mem::forget(unerased._object)
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<E>.
|
|
unsafe fn object_ref<E>(e: RefPtr<'_, ErrorImpl<()>>) -> &(dyn StdError + Send + Sync + 'static)
|
|
where
|
|
E: StdError + Send + Sync + 'static,
|
|
{
|
|
// Attach E's native StdError vtable onto a pointer to self._object.
|
|
&unsafe { e.cast::<ErrorImpl<E>>().as_ref() }._object
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<E>.
|
|
unsafe fn object_mut<E>(e: MutPtr<'_, ErrorImpl<()>>) -> &mut (dyn StdError + Send + Sync + 'static)
|
|
where
|
|
E: StdError + Send + Sync + 'static,
|
|
{
|
|
// Attach E's native StdError vtable onto a pointer to self._object.
|
|
&mut unsafe { e.cast::<ErrorImpl<E>>().into_mut() }._object
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<E>.
|
|
unsafe fn object_boxed<E>(e: OwnedPtr<ErrorImpl<()>>) -> Box<dyn StdError + Send + Sync + 'static>
|
|
where
|
|
E: StdError + Send + Sync + 'static,
|
|
{
|
|
// Attach ErrorImpl<E>'s native StdError vtable. The StdError impl is below.
|
|
unsafe { e.cast::<ErrorImpl<E>>().into_box() }
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<E>.
|
|
unsafe fn object_downcast<E>(e: RefPtr<'_, ErrorImpl<()>>, target: TypeId) -> Option<NonNull<()>>
|
|
where
|
|
E: 'static,
|
|
{
|
|
if TypeId::of::<E>() == target {
|
|
// Caller is looking for an E pointer and e is ErrorImpl<E>, take a
|
|
// pointer to its E field.
|
|
let unerased = unsafe { e.cast::<ErrorImpl<E>>().as_ref() };
|
|
Some(NonNull::from(&(unerased._object)).cast::<()>())
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<E>.
|
|
unsafe fn object_downcast_mut<E>(
|
|
e: MutPtr<'_, ErrorImpl<()>>,
|
|
target: TypeId,
|
|
) -> Option<NonNull<()>>
|
|
where
|
|
E: 'static,
|
|
{
|
|
if TypeId::of::<E>() == target {
|
|
// Caller is looking for an E pointer and e is ErrorImpl<E>, take a
|
|
// pointer to its E field.
|
|
let unerased = unsafe { e.cast::<ErrorImpl<E>>().into_mut() };
|
|
Some(NonNull::from(&mut (unerased._object)).cast::<()>())
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<ContextError<D, E>>.
|
|
unsafe fn context_downcast<D, E>(
|
|
e: RefPtr<'_, ErrorImpl<()>>,
|
|
target: TypeId,
|
|
) -> Option<NonNull<()>>
|
|
where
|
|
D: 'static,
|
|
E: 'static,
|
|
{
|
|
if TypeId::of::<D>() == target {
|
|
let unerased = unsafe { e.cast::<ErrorImpl<ContextError<D, E>>>().as_ref() };
|
|
let addr = NonNull::from(&unerased._object.msg).cast::<()>();
|
|
Some(addr)
|
|
} else if TypeId::of::<E>() == target {
|
|
let unerased = unsafe { e.cast::<ErrorImpl<ContextError<D, E>>>().as_ref() };
|
|
let addr = NonNull::from(&unerased._object.error).cast::<()>();
|
|
Some(addr)
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<ContextError<D, E>>.
|
|
unsafe fn context_downcast_mut<D, E>(
|
|
e: MutPtr<'_, ErrorImpl<()>>,
|
|
target: TypeId,
|
|
) -> Option<NonNull<()>>
|
|
where
|
|
D: 'static,
|
|
E: 'static,
|
|
{
|
|
if TypeId::of::<D>() == target {
|
|
let unerased = unsafe { e.cast::<ErrorImpl<ContextError<D, E>>>().into_mut() };
|
|
let addr = NonNull::from(&unerased._object.msg).cast::<()>();
|
|
Some(addr)
|
|
} else if TypeId::of::<E>() == target {
|
|
let unerased = unsafe { e.cast::<ErrorImpl<ContextError<D, E>>>().into_mut() };
|
|
let addr = NonNull::from(&mut unerased._object.error).cast::<()>();
|
|
Some(addr)
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<ContextError<D, E>>.
|
|
unsafe fn context_drop_rest<D, E>(e: OwnedPtr<ErrorImpl<()>>, target: TypeId)
|
|
where
|
|
D: 'static,
|
|
E: 'static,
|
|
{
|
|
// Called after downcasting by value to either the D or the E and doing a
|
|
// ptr::read to take ownership of that value.
|
|
if TypeId::of::<D>() == target {
|
|
unsafe {
|
|
e.cast::<ErrorImpl<ContextError<ManuallyDrop<D>, E>>>()
|
|
.into_box()
|
|
};
|
|
} else {
|
|
debug_assert_eq!(TypeId::of::<E>(), target);
|
|
unsafe {
|
|
e.cast::<ErrorImpl<ContextError<D, ManuallyDrop<E>>>>()
|
|
.into_box()
|
|
};
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<ContextError<D, Report>>.
|
|
unsafe fn context_chain_downcast<D>(
|
|
e: RefPtr<'_, ErrorImpl<()>>,
|
|
target: TypeId,
|
|
) -> Option<NonNull<()>>
|
|
where
|
|
D: 'static,
|
|
{
|
|
let unerased = unsafe { e.cast::<ErrorImpl<ContextError<D, Report>>>().as_ref() };
|
|
if TypeId::of::<D>() == target {
|
|
let addr = NonNull::from(&unerased._object.msg).cast::<()>();
|
|
Some(addr)
|
|
} else {
|
|
// Recurse down the context chain per the inner error's vtable.
|
|
let source = &unerased._object.error;
|
|
unsafe { (source.vtable().object_downcast)(source.inner.as_ref(), target) }
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<ContextError<D, Report>>.
|
|
unsafe fn context_chain_downcast_mut<D>(
|
|
e: MutPtr<'_, ErrorImpl<()>>,
|
|
target: TypeId,
|
|
) -> Option<NonNull<()>>
|
|
where
|
|
D: 'static,
|
|
{
|
|
let unerased = unsafe { e.cast::<ErrorImpl<ContextError<D, Report>>>().into_mut() };
|
|
if TypeId::of::<D>() == target {
|
|
let addr = NonNull::from(&unerased._object.msg).cast::<()>();
|
|
Some(addr)
|
|
} else {
|
|
// Recurse down the context chain per the inner error's vtable.
|
|
let source = &mut unerased._object.error;
|
|
unsafe { (source.vtable().object_downcast_mut)(source.inner.as_mut(), target) }
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// Requires layout of *e to match ErrorImpl<ContextError<D, Report>>.
|
|
unsafe fn context_chain_drop_rest<D>(e: OwnedPtr<ErrorImpl<()>>, target: TypeId)
|
|
where
|
|
D: 'static,
|
|
{
|
|
// Called after downcasting by value to either the D or one of the causes
|
|
// and doing a ptr::read to take ownership of that value.
|
|
if TypeId::of::<D>() == target {
|
|
let unerased = unsafe {
|
|
e.cast::<ErrorImpl<ContextError<ManuallyDrop<D>, Report>>>()
|
|
.into_box()
|
|
};
|
|
// Drop the entire rest of the data structure rooted in the next Report.
|
|
drop(unerased);
|
|
} else {
|
|
unsafe {
|
|
let unerased = e
|
|
.cast::<ErrorImpl<ContextError<D, ManuallyDrop<Report>>>>()
|
|
.into_box();
|
|
// Read out a ManuallyDrop<Box<ErrorImpl<()>>> from the next error.
|
|
let inner = ptr::read(&unerased.as_ref()._object.error.inner);
|
|
drop(unerased);
|
|
// Recursively drop the next error using the same target typeid.
|
|
(header(inner.as_ref()).vtable.object_drop_rest)(inner, target);
|
|
}
|
|
}
|
|
}
|
|
|
|
#[repr(C)]
|
|
pub(crate) struct ErrorHeader {
|
|
vtable: &'static ErrorVTable,
|
|
pub(crate) handler: Option<Box<dyn EyreHandler>>,
|
|
}
|
|
|
|
// repr C to ensure that E remains in the final position.
|
|
#[repr(C)]
|
|
pub(crate) struct ErrorImpl<E = ()> {
|
|
header: ErrorHeader,
|
|
// NOTE: Don't use directly. Use only through vtable. Erased type may have
|
|
// different alignment.
|
|
_object: E,
|
|
}
|
|
|
|
// repr C to ensure that ContextError<D, E> has the same layout as
|
|
// ContextError<ManuallyDrop<D>, E> and ContextError<D, ManuallyDrop<E>>.
|
|
#[repr(C)]
|
|
pub(crate) struct ContextError<D, E> {
|
|
pub(crate) msg: D,
|
|
pub(crate) error: E,
|
|
}
|
|
|
|
impl<E> ErrorImpl<E> {
|
|
/// Returns a type erased Error
|
|
fn erase(&self) -> RefPtr<'_, ErrorImpl<()>> {
|
|
// Erase the concrete type of E but preserve the vtable in self.vtable
|
|
// for manipulating the resulting thin pointer. This is analogous to an
|
|
// unsize coersion.
|
|
RefPtr::new(self).cast()
|
|
}
|
|
}
|
|
|
|
// Reads the header out of `p`. This is the same as `p.as_ref().header`, but
|
|
// avoids converting `p` into a reference of a shrunk provenance with a type different than the
|
|
// allocation.
|
|
fn header(p: RefPtr<'_, ErrorImpl<()>>) -> &'_ ErrorHeader {
|
|
// Safety: `ErrorHeader` is the first field of repr(C) `ErrorImpl`
|
|
unsafe { p.cast().as_ref() }
|
|
}
|
|
|
|
fn header_mut(p: MutPtr<'_, ErrorImpl<()>>) -> &mut ErrorHeader {
|
|
// Safety: `ErrorHeader` is the first field of repr(C) `ErrorImpl`
|
|
unsafe { p.cast().into_mut() }
|
|
}
|
|
|
|
impl ErrorImpl<()> {
|
|
pub(crate) fn error(this: RefPtr<'_, Self>) -> &(dyn StdError + Send + Sync + 'static) {
|
|
// Use vtable to attach E's native StdError vtable for the right
|
|
// original type E.
|
|
unsafe { (header(this).vtable.object_ref)(this) }
|
|
}
|
|
|
|
pub(crate) fn error_mut(this: MutPtr<'_, Self>) -> &mut (dyn StdError + Send + Sync + 'static) {
|
|
// Use vtable to attach E's native StdError vtable for the right
|
|
// original type E.
|
|
unsafe { (header_mut(this).vtable.object_mut)(this) }
|
|
}
|
|
|
|
pub(crate) fn chain(this: RefPtr<'_, Self>) -> Chain<'_> {
|
|
Chain::new(Self::error(this))
|
|
}
|
|
|
|
pub(crate) fn header(this: RefPtr<'_, ErrorImpl>) -> &ErrorHeader {
|
|
header(this)
|
|
}
|
|
}
|
|
|
|
impl<E> StdError for ErrorImpl<E>
|
|
where
|
|
E: StdError,
|
|
{
|
|
fn source(&self) -> Option<&(dyn StdError + 'static)> {
|
|
ErrorImpl::<()>::error(self.erase()).source()
|
|
}
|
|
}
|
|
|
|
impl<E> Debug for ErrorImpl<E>
|
|
where
|
|
E: Debug,
|
|
{
|
|
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
ErrorImpl::debug(self.erase(), formatter)
|
|
}
|
|
}
|
|
|
|
impl<E> Display for ErrorImpl<E>
|
|
where
|
|
E: Display,
|
|
{
|
|
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
Display::fmt(ErrorImpl::error(self.erase()), formatter)
|
|
}
|
|
}
|
|
|
|
impl From<Report> for Box<dyn StdError + Send + Sync + 'static> {
|
|
fn from(error: Report) -> Self {
|
|
let outer = ManuallyDrop::new(error);
|
|
unsafe {
|
|
// Read Box<ErrorImpl<()>> from error. Can't move it out because
|
|
// Report has a Drop impl which we want to not run.
|
|
// Use vtable to attach ErrorImpl<E>'s native StdError vtable for
|
|
// the right original type E.
|
|
(header(outer.inner.as_ref()).vtable.object_boxed)(outer.inner)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl From<Report> for Box<dyn StdError + 'static> {
|
|
fn from(error: Report) -> Self {
|
|
Box::<dyn StdError + Send + Sync>::from(error)
|
|
}
|
|
}
|
|
|
|
impl AsRef<dyn StdError + Send + Sync> for Report {
|
|
fn as_ref(&self) -> &(dyn StdError + Send + Sync + 'static) {
|
|
&**self
|
|
}
|
|
}
|
|
|
|
impl AsRef<dyn StdError> for Report {
|
|
fn as_ref(&self) -> &(dyn StdError + 'static) {
|
|
&**self
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "pyo3")]
|
|
mod pyo3_compat;
|