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Rollup merge of #128632 - joboet:dont_overwrite_style, r=Amanieu

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std: do not overwrite style in `get_backtrace_style`

If another thread calls `set_backtrace_style` while a `get_backtrace_style` is reading the environment variables, `get_backtrace_style` will overwrite the value. Use an atomic CAS to avoid this.
This commit is contained in:
Guillaume Gomez 2024-08-12 17:09:16 +02:00 committed by GitHub
commit aa6f240972
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1 changed files with 15 additions and 11 deletions
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26
library/std/src/panic.rs
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@ -440,13 +440,12 @@ impl BacktraceStyle {
} }
fn from_u8(s: u8) -> Option<Self> { fn from_u8(s: u8) -> Option<Self> {
Some(match s { match s {
0 => return None, 1 => Some(BacktraceStyle::Short),
1 => BacktraceStyle::Short, 2 => Some(BacktraceStyle::Full),
2 => BacktraceStyle::Full, 3 => Some(BacktraceStyle::Off),
3 => BacktraceStyle::Off, _ => None,
_ => unreachable!(), }
})
} }
} }
@ -465,7 +464,7 @@ static SHOULD_CAPTURE: AtomicU8 = AtomicU8::new(0);
pub fn set_backtrace_style(style: BacktraceStyle) { pub fn set_backtrace_style(style: BacktraceStyle) {
if cfg!(feature = "backtrace") { if cfg!(feature = "backtrace") {
// If the `backtrace` feature of this crate is enabled, set the backtrace style. // If the `backtrace` feature of this crate is enabled, set the backtrace style.
SHOULD_CAPTURE.store(style.as_u8(), Ordering::Release); SHOULD_CAPTURE.store(style.as_u8(), Ordering::Relaxed);
} }
} }
@ -498,7 +497,9 @@ pub fn get_backtrace_style() -> Option<BacktraceStyle> {
// to optimize away callers. // to optimize away callers.
return None; return None;
} }
if let Some(style) = BacktraceStyle::from_u8(SHOULD_CAPTURE.load(Ordering::Acquire)) {
let current = SHOULD_CAPTURE.load(Ordering::Relaxed);
if let Some(style) = BacktraceStyle::from_u8(current) {
return Some(style); return Some(style);
} }
@ -509,8 +510,11 @@ pub fn get_backtrace_style() -> Option<BacktraceStyle> {
None if crate::sys::FULL_BACKTRACE_DEFAULT => BacktraceStyle::Full, None if crate::sys::FULL_BACKTRACE_DEFAULT => BacktraceStyle::Full,
None => BacktraceStyle::Off, None => BacktraceStyle::Off,
}; };
set_backtrace_style(format);
Some(format) match SHOULD_CAPTURE.compare_exchange(0, format.as_u8(), Ordering::Relaxed, Ordering::Relaxed) {
Ok(_) => Some(format),
Err(new) => BacktraceStyle::from_u8(new),
}
} }
#[cfg(test)] #[cfg(test)]