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Guard against calling libc::exit multiple times on Linux. #126606

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merged 12 commits into from
Jul 13, 2024
+77 −0
Merged

Guard against calling libc::exit multiple times on Linux. #126606

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e71d06b
On `target_os = "linux"`, ensure that only one Rust thread calls `lib…
zachs18 Jun 18, 2024
bff3531
fix rustdoc URL
zachs18 Jun 21, 2024
c36fdeb
Don't perform mitigation for thread-unsafe libc::exit under Miri.
zachs18 Jun 21, 2024
5e83faf
Use libc::pause instead of std::thread::park in wait-for-exit loop
zachs18 Jul 3, 2024
897fb6c
Use pthread_t instead of numeric thread id
zachs18 Jul 3, 2024
b512608
Remove Miri special-case
zachs18 Jul 3, 2024
b4149c6
Move unique_thread_exit call to lang_start_internal so it is not in a…
zachs18 Jul 3, 2024
9de76e3
Update library/std/src/sys/pal/common/exit_guard.rs
zachs18 Jul 5, 2024
a609370
Move exit guard from sys::common::exit_guard to sys::exit_guard.
zachs18 Jul 5, 2024
5db1655
Attempt to fix CI
zachs18 Jul 5, 2024
9801076
Move/change declaration of `mod exit_guard;`
zachs18 Jul 7, 2024
8bcbab5
Attempt to fix CI
zachs18 Jul 8, 2024
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Attempt to fix CI
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@zachs18
zachs18 authored Jul 8, 2024
commit 8bcbab5dd1c6449c2acd3ea6a94b245c0936722d
15 changes: 12 additions & 3 deletions library/std/src/sys/exit_guard.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,14 @@
cfg_if::cfg_if! {
if #[cfg(target_os = "linux")] {
/// pthread_t is a pointer on some platforms,
/// so we wrap it in this to impl Send + Sync.
#[derive(Clone, Copy)]
#[repr(transparent)]
struct PThread(libc::pthread_t);
// Safety: pthread_t is safe to send between threads
unsafe impl Send for PThread {}
// Safety: pthread_t is safe to share between threads
unsafe impl Sync for PThread {}
/// Mitigation for <https://github.com/rust-lang/rust/issues/126600>
///
/// On glibc, `libc::exit` has been observed to not always be thread-safe.
Expand All @@ -23,17 +32,17 @@ cfg_if::cfg_if! {
pub(crate) fn unique_thread_exit() {
let this_thread_id = unsafe { libc::pthread_self() };
use crate::sync::{Mutex, PoisonError};
static EXITING_THREAD_ID: Mutex<Option<libc::pthread_t>> = Mutex::new(None);
static EXITING_THREAD_ID: Mutex<Option<PThread>> = Mutex::new(None);
let mut exiting_thread_id =
EXITING_THREAD_ID.lock().unwrap_or_else(PoisonError::into_inner);
match *exiting_thread_id {
None => {
// This is the first thread to call `unique_thread_exit`,
// and this is the first time it is called.
// Set EXITING_THREAD_ID to this thread's ID and return.
*exiting_thread_id = Some(this_thread_id);
*exiting_thread_id = Some(PThread(this_thread_id));
},
Some(exiting_thread_id) if exiting_thread_id == this_thread_id => {
Some(exiting_thread_id) if exiting_thread_id.0 == this_thread_id => {
// This is the first thread to call `unique_thread_exit`,
// but this is the second time it is called.
// Abort the process.
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