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Add comment explaining false positives in _destroy

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5225225 2021-12-07 08:26:46 +00:00
parent a4b2fc0c5a
commit 250d450593
1 changed files with 16 additions and 0 deletions
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16
src/shims/posix/sync.rs
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@ -367,6 +367,18 @@ fn pthread_mutexattr_destroy(&mut self, attr_op: &OpTy<'tcx, Tag>) -> InterpResu
// Destroying an uninit pthread_mutexattr is UB, so check to make sure it's not uninit.
mutexattr_get_kind(this, attr_op)?.check_init()?;
// This is technically not right and might lead to false positives. For example, the below
// code is *likely* sound, even assuming uninit numbers are UB, but miri with
// -Zmiri-check-number-validity complains
//
// let mut x: MaybeUninit<libc::pthread_mutexattr_t> = MaybeUninit::zeroed();
// libc::pthread_mutexattr_init(x.as_mut_ptr());
// libc::pthread_mutexattr_destroy(x.as_mut_ptr());
// x.assume_init();
//
// This can always be revisited to have some external state to catch double-destroys
// but not complain about the above code. See https://github.com/rust-lang/miri/pull/1933
mutexattr_set_kind(this, attr_op, ScalarMaybeUninit::Uninit)?;
Ok(0)
@ -509,6 +521,7 @@ fn pthread_mutex_destroy(&mut self, mutex_op: &OpTy<'tcx, Tag>) -> InterpResult<
mutex_get_kind(this, mutex_op)?.check_init()?;
mutex_get_id(this, mutex_op)?.check_init()?;
// This might lead to false positives, see comment in pthread_mutexattr_destroy
mutex_set_kind(this, mutex_op, ScalarMaybeUninit::Uninit)?;
mutex_set_id(this, mutex_op, ScalarMaybeUninit::Uninit)?;
// FIXME: delete interpreter state associated with this mutex.
@ -613,6 +626,7 @@ fn pthread_rwlock_destroy(&mut self, rwlock_op: &OpTy<'tcx, Tag>) -> InterpResul
// Destroying an uninit pthread_rwlock is UB, so check to make sure it's not uninit.
rwlock_get_id(this, rwlock_op)?.check_init()?;
// This might lead to false positives, see comment in pthread_mutexattr_destroy
rwlock_set_id(this, rwlock_op, ScalarMaybeUninit::Uninit)?;
// FIXME: delete interpreter state associated with this rwlock.
@ -670,6 +684,7 @@ fn pthread_condattr_destroy(&mut self, attr_op: &OpTy<'tcx, Tag>) -> InterpResul
// Destroying an uninit pthread_condattr is UB, so check to make sure it's not uninit.
condattr_get_clock_id(this, attr_op)?.check_init()?;
// This might lead to false positives, see comment in pthread_mutexattr_destroy
condattr_set_clock_id(this, attr_op, ScalarMaybeUninit::Uninit)?;
Ok(0)
@ -812,6 +827,7 @@ fn pthread_cond_destroy(&mut self, cond_op: &OpTy<'tcx, Tag>) -> InterpResult<'t
cond_get_id(this, cond_op)?.check_init()?;
cond_get_clock_id(this, cond_op)?.check_init()?;
// This might lead to false positives, see comment in pthread_mutexattr_destroy
cond_set_id(this, cond_op, ScalarMaybeUninit::Uninit)?;
cond_set_clock_id(this, cond_op, ScalarMaybeUninit::Uninit)?;
// FIXME: delete interpreter state associated with this condvar.