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fix threading issue: don't assign to the global lock state struct until we're safely inside the mutex.

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Otherwise, we might be overwriting the global lock state from two different
threads at once.
This commit is contained in:
Mathis Beer
2020-03-12 06:37:05 +01:00
parent b4dea2ef9b
commit a12ca58dfa
1 changed files with 5 additions and 3 deletions
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8
src/libfaketime.c
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@@ -2636,8 +2636,9 @@ struct LockedState {
static void pthread_cleanup_mutex_lock(void *data)
{
struct LockedState *state = data;
sigset_t original_mask = state->original_mask; // inside the lock!
pthread_mutex_unlock(&state->mutex);
pthread_sigmask(SIG_SETMASK, &state->original_mask, NULL);
pthread_sigmask(SIG_SETMASK, &original_mask, NULL);
}
#endif
@@ -2673,10 +2674,11 @@ int fake_clock_gettime(clockid_t clk_id, struct timespec *tp)
static struct LockedState state = { 0 };
// block all signals while locked. prevents deadlocks if signal interrupts in in mid-operation.
sigset_t all_signals;
sigset_t all_signals, original_mask;
sigfillset(&all_signals);
pthread_sigmask(SIG_SETMASK, &all_signals, &state.original_mask);
pthread_sigmask(SIG_SETMASK, &all_signals, &original_mask);
pthread_mutex_lock(&state.mutex);
state.original_mask = original_mask; // inside the lock!
pthread_cleanup_push(pthread_cleanup_mutex_lock, &state);
#endif