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use core::{ cell::RefCell, fmt::{self, Debug, Display}, panic::PanicInfo, }; use lazy_static::lazy_static; use std::{ panic::{catch_unwind, AssertUnwindSafe, RefUnwindSafe}, thread_local, }; macro_rules! backtrace { () => {{ if CAPTURE_BACKTRACE.with(|capture| *capture.borrow()) { Some(mini_backtrace()) } else { None } }}; } thread_local! { static ERROR: RefCell<Option<PanicError>> = RefCell::new(None); static CAPTURE_BACKTRACE: RefCell<bool> = RefCell::new(*RUST_BACKTRACE); static FORWARD_PANIC: RefCell<bool> = RefCell::new(true); static THREAD_NAME: String = String::from(std::thread::current().name().unwrap_or("main")); } lazy_static! { static ref RUST_BACKTRACE: bool = std::env::var("RUST_BACKTRACE") .ok() .map(|v| v == "1") .unwrap_or(false); static ref PANIC_HOOK: () = { let prev_hook = std::panic::take_hook(); std::panic::set_hook(Box::new(move |reason| { let panic = PanicError { message: reason.to_string(), location: reason.location().map(|l| l.to_string()), backtrace: backtrace!(), thread_name: thread_name(), }; ERROR.with(|error| { *error.borrow_mut() = Some(panic); }); if FORWARD_PANIC.with(|forward| *forward.borrow()) { prev_hook(reason); } })); }; } #[derive(Debug)] pub struct PanicError { pub(crate) message: String, pub(crate) location: Option<String>, pub(crate) backtrace: Option<Backtrace>, pub(crate) thread_name: String, } impl std::error::Error for PanicError {} impl Display for PanicError { fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result { write!(f, "{}", self.message) } } impl PanicError { pub(crate) fn new(message: String) -> Self { Self { message, location: None, backtrace: backtrace!(), thread_name: thread_name(), } } } pub fn catch<F: RefUnwindSafe + FnOnce() -> Output, Output>(fun: F) -> Result<Output, PanicError> { catch_unwind(AssertUnwindSafe(|| __panic_marker_start__(fun))).map_err(|err| { if let Some(err) = take_panic() { return err; } macro_rules! try_downcast { ($ty:ty, $fmt:expr) => { if let Some(err) = err.downcast_ref::<$ty>() { return PanicError::new(format!($fmt, err)); } }; } try_downcast!(PanicInfo, "{}"); try_downcast!(anyhow::Error, "{}"); try_downcast!(String, "{}"); try_downcast!(&'static str, "{}"); try_downcast!(Box<dyn Display>, "{}"); try_downcast!(Box<dyn Debug>, "{:?}"); PanicError::new("thread panicked with an unknown error".to_string()) }) } pub fn take_panic() -> Option<PanicError> { ERROR.with(|error| error.borrow_mut().take()) } pub fn capture_backtrace(value: bool) -> bool { CAPTURE_BACKTRACE.with(|cell| { let prev = *cell.borrow(); *cell.borrow_mut() = value; prev }) } pub fn forward_panic(value: bool) -> bool { FORWARD_PANIC.with(|cell| { let prev = *cell.borrow(); *cell.borrow_mut() = value; prev }) } pub fn set_hook() { *PANIC_HOOK } pub fn rust_backtrace() -> bool { *RUST_BACKTRACE } pub fn thread_name() -> String { THREAD_NAME.with(|cell| cell.clone()) } #[inline(never)] fn mini_backtrace() -> Backtrace { let mut frames = vec![]; enum State { Backtrace, ThisCrate, Application, } let mut state = State::Backtrace; let parent = std::path::Path::new(file!()).parent().unwrap(); backtrace::trace(|frame| { let mut is_done = false; backtrace::resolve_frame(frame, |symbol| { let is_this_crate = symbol .filename() .map(|path| path.starts_with(parent)) .unwrap_or(false); match state { State::Backtrace => { if is_this_crate { state = State::ThisCrate; } } State::ThisCrate => { if is_this_crate { } else { state = State::Application; } } State::Application => { if is_this_crate { is_done = true; } else if let Some(frame) = BacktraceFrame::from_symbol(symbol) { frames.push(frame); } } } }); !is_done }); Backtrace::new(frames) } #[inline(never)] fn __panic_marker_start__<F: FnOnce() -> R, R>(f: F) -> R { f() } #[derive(Debug)] pub struct Backtrace { frames: Vec<BacktraceFrame>, } impl Display for Backtrace { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { for (i, frame) in self.frames.iter().enumerate() { writeln!(f, " {}: {}", i, frame.symbol)?; if let Some(location) = frame.location.as_ref() { writeln!(f, " at {}", location)?; } } Ok(()) } } #[derive(Debug)] pub struct BacktraceFrame { symbol: String, location: Option<String>, } impl BacktraceFrame { fn from_symbol(symbol: &backtrace::Symbol) -> Option<Self> { let name = format!("{:#}", symbol.name()?); Some(BacktraceFrame { symbol: name, location: symbol.filename().map(|filename| { if let Some(lineno) = symbol.lineno() { format!("{}:{}", filename.display(), lineno) } else { filename.display().to_string() } }), }) } } impl Backtrace { fn new(frames: Vec<BacktraceFrame>) -> Self { Self { frames } } }