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//! The InternalError type, macro for generating it, etc.
use std::fmt::{self, Debug, Display};
use std::panic;
use std::sync::Arc;
use super::*;
#[cfg(feature = "backtrace")]
/// Backtrace implementation for when the feature is enabled
mod ie_backtrace {
use super::*;
// TODO MSRV 1.65: std::backtrace::Backtrace is stable; maybe we should be
// using that instead?
use backtrace::Backtrace;
#[derive(Debug, Clone)]
/// Captured backtrace, if turned on
pub(crate) struct Captured(Backtrace);
/// Capture a backtrace, if turned on
pub(crate) fn capture() -> Captured {
Captured(Backtrace::new())
}
impl Display for Captured {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Debug::fmt(&self.0, f)
}
}
}
#[cfg(not(feature = "backtrace"))]
/// Backtrace implementation for when the feature is disabled
mod ie_backtrace {
use super::*;
#[derive(Debug, Clone)]
/// "Captured backtrace", but actually nothing
pub(crate) struct Captured;
/// "Capture a backtrace", but actually return nothing
pub(crate) fn capture() -> Captured {
Captured
}
impl Display for Captured {
fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
Ok(())
}
}
}
#[derive(Debug, Clone)]
/// Programming error (a bug)
//
// Boxed because it is fairly large (>=12 words), and will be in a variant in many other errors.
//
// This is a single Bug type containing a kind in BugRepr, rather than separate InternalError and
// BadApiUsage types, primarily because that means that one Bug(#[from] tor_error::Bug) suffices in
// every crate's particular error type.
pub struct Bug(Box<BugRepr>);
/// The source of an Bug
type SourceError = Arc<dyn std::error::Error + Send + Sync + 'static>;
#[derive(Debug, Clone)]
/// Internal error (a bug)
struct BugRepr {
/// Message, usually from internal!() like format!
message: String,
/// File and line number
location: &'static panic::Location<'static>,
/// Backtrace, perhaps
backtrace: ie_backtrace::Captured,
/// Source, perhaps
source: Option<SourceError>,
/// Kind
///
/// `Internal` or `BadApiUsage`
kind: ErrorKind,
}
impl Bug {
/// Create a bug error report capturing this call site and backtrace
///
/// Prefer to use [`internal!`],
/// as that makes it easy to add additional information
/// via format parameters.
#[track_caller]
pub fn new<S: Into<String>>(kind: ErrorKind, message: S) -> Self {
Bug::new_inner(kind, message.into(), None)
}
/// Create an internal error
#[track_caller]
fn new_inner(kind: ErrorKind, message: String, source: Option<SourceError>) -> Self {
Bug(BugRepr {
kind,
message,
source,
location: panic::Location::caller(),
backtrace: ie_backtrace::capture(),
}
.into())
}
/// Create an bug error report from another error, capturing this call site and backtrace
///
/// In `map_err`, and perhaps elsewhere, prefer to use [`into_internal!`],
/// as that makes it easy to add additional information
/// via format parameters.
#[track_caller]
pub fn from_error<E, S>(kind: ErrorKind, source: E, message: S) -> Self
where
S: Into<String>,
E: std::error::Error + Send + Sync + 'static,
{
Bug::new_inner(kind, message.into(), Some(Arc::new(source)))
}
}
impl std::error::Error for Bug {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
self.0
.source
.as_deref()
.map(|traitobj| traitobj as _ /* cast away Send and Sync */)
}
}
impl Display for Bug {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
writeln!(
f,
"{} at {}: {}",
self.0.kind, &self.0.location, &self.0.message
)?;
Display::fmt(&self.0.backtrace, f)?;
Ok(())
}
}
/// Create an internal error, including a message like `format!`, and capturing this call site
///
/// The calling stack backtrace is also captured,
/// when the `backtrace` cargo feature this is enabled.
///
/// # Examples
///
/// ```
/// use tor_error::internal;
///
/// # fn main() -> Result<(), tor_error::Bug> {
/// # let mut cells = [()].iter();
/// let need_cell = cells.next().ok_or_else(|| internal!("no cells"))?;
/// # Ok(())
/// # }
/// ```
//
// In principle this macro could perhaps support internal!(from=source, "format", ...)
// but there are alternative ways of writing that:
// Bug::new_from(source, format!(...)) or
// into_internal!("format", ...)(source)
// Those are not so bad for what we think will be the rare cases not
// covered by internal!(...) or map_err(into_internal!(...))
#[macro_export]
macro_rules! internal {
{ $( $arg:tt )* } => {
$crate::Bug::new($crate::ErrorKind::Internal, format!($($arg)*))
}
}
/// Create a bad API usage error, including a message like `format!`, and capturing this call site
///
/// The calling stack backtrace is also captured,
/// when the `backtrace` cargo feature this is enabled.
///
/// # Examples
///
/// ```
/// use tor_error::bad_api_usage;
///
/// # fn main() -> Result<(), tor_error::Bug> {
/// # let mut targets = [()].iter();
/// let need_target = targets.next().ok_or_else(|| bad_api_usage!("no targets"))?;
/// # Ok(())
/// # }
#[macro_export]
macro_rules! bad_api_usage {
{ $( $arg:tt )* } => {
$crate::Bug::new($crate::ErrorKind::BadApiUsage, format!($($arg)*))
}
}
/// Helper for converting an error into an internal error
///
/// Returns a closure implementing `FnOnce(E) -> Bug`.
/// The source error `E` must be `std::error::Error + Send + Sync + 'static`.
///
/// # Examples
/// ```
/// use tor_error::into_internal;
///
/// # fn main() -> Result<(), tor_error::Bug> {
/// # let s = b"";
/// let s = std::str::from_utf8(s).map_err(into_internal!("bad bytes: {:?}", s))?;
/// # Ok(())
/// # }
/// ```
#[macro_export]
macro_rules! into_internal {
{ $( $arg:tt )* } => {
std::convert::identity( // Hides the IEFI from clippy::redundant_closure_call
|source| $crate::Bug::from_error($crate::ErrorKind::Internal, source, format!($($arg)*))
)
}
}
/// Helper for converting an error into an bad API usage error
///
/// Returns a closure implementing `FnOnce(E) -> InternalError`.
/// The source error `E` must be `std::error::Error + Send + Sync + 'static`.
///
/// # Examples
/// ```
/// use tor_error::into_bad_api_usage;
///
/// # fn main() -> Result<(), tor_error::Bug> {
/// # let host = b"";
/// let host = std::str::from_utf8(host).map_err(into_bad_api_usage!("hostname is bad UTF-8: {:?}", host))?;
/// # Ok(())
/// # }
/// ```
#[macro_export]
macro_rules! into_bad_api_usage {
{ $( $arg:tt )* } => {
std::convert::identity( // Hides the IEFI from clippy::redundant_closure_call
|source| $crate::Bug::from_error($crate::ErrorKind::BadApiUsage, source, format!($($arg)*))
)
}
}
impl HasKind for Bug {
fn kind(&self) -> ErrorKind {
self.0.kind
}
}
#[cfg(test)]
mod test {
// @@ begin test lint list maintained by maint/add_warning @@
#![allow(clippy::bool_assert_comparison)]
#![allow(clippy::clone_on_copy)]
#![allow(clippy::dbg_macro)]
#![allow(clippy::mixed_attributes_style)]
#![allow(clippy::print_stderr)]
#![allow(clippy::print_stdout)]
#![allow(clippy::single_char_pattern)]
#![allow(clippy::unwrap_used)]
#![allow(clippy::unchecked_duration_subtraction)]
#![allow(clippy::useless_vec)]
#![allow(clippy::needless_pass_by_value)]
//! <!-- @@ end test lint list maintained by maint/add_warning @@ -->
use super::*;
// We test this on "important" and "reliable" platforms only.
//
// This test case mainly is to ensure that we are using the backtrace module correctly, etc.,
// which can be checked by doing it on one platform.
//
// Doing the test on on *all* platforms would simply expose us to the vagaries of platform
// backtrace support. Arti ought not to fail its tests just because someone is using a
// platform with poor backtrace support.
//
// On the other hand, we *do* want to know that things are correct on platforms where we think
// Rust backtraces work properly.
//
// So this list is a compromise. See
// https://gitlab.torproject.org/tpo/core/arti/-/merge_requests/509#note_2803085
#[cfg(any(target_os = "linux", target_os = "macos", target_os = "windows"))]
#[test]
#[inline(never)]
fn internal_macro_test() {
let start_of_func = line!();
let e = internal!("Couldn't {} the {}.", "wobble", "wobbling device");
assert_eq!(e.0.message, "Couldn't wobble the wobbling device.");
assert!(e.0.location.file().ends_with("internal.rs"));
assert!(e.0.location.line() > start_of_func);
assert!(e.0.source.is_none());
let s = e.to_string();
dbg!(&s);
assert!(s.starts_with("internal error (bug) at "));
assert!(s.contains("Couldn't wobble the wobbling device."));
#[cfg(feature = "backtrace")]
assert!(s.contains("internal_macro_test"));
#[derive(thiserror::Error, Debug)]
enum Wrap {
#[error("Internal error")]
Internal(#[from] Bug),
}
let w: Wrap = e.into();
let s = format!("Got: {}", w.report());
dbg!(&s);
assert!(s.contains("Couldn't wobble the wobbling device."));
}
#[test]
fn source() {
use std::error::Error;
use std::str::FromStr;
let start_of_func = line!();
let s = "penguin";
let inner = u32::from_str(s).unwrap_err();
let outer = u32::from_str(s)
.map_err(into_internal!("{} is not a number", s))
.unwrap_err();
let afterwards = line!();
assert_eq!(outer.source().unwrap().to_string(), inner.to_string());
assert!(outer.0.location.line() > start_of_func);
assert!(outer.0.location.line() < afterwards);
}
}