That was good, but there's still a multithreading issue, as the signal handler
may be executing in a different thread.
2020-06-27 Bruno Haible <br...@clisp.org>
fatal-signal: Make multithread-safe.
* lib/fatal-signal.c (at_fatal_signal): Don't free the old actions
array.
diff --git a/lib/fatal-signal.c b/lib/fatal-signal.c
index 975393b..c6f8dac 100644
--- a/lib/fatal-signal.c
+++ b/lib/fatal-signal.c
@@ -239,8 +239,15 @@ at_fatal_signal (action_t action)
actions = new_actions;
actions_allocated = new_actions_allocated;
/* Now we can free the old actions array. */
+ /* No, we can't do that. If fatal_signal_handler is running in a
+ different thread and has already fetched the actions pointer (getting
+ old_actions) but not yet accessed its n-th element, that thread may
+ crash when accessing an element of the already freed old_actions
+ array. */
+ #if 0
if (old_actions != static_actions)
free (old_actions);
+ #endif
}
/* The two uses of 'volatile' in the types above (and ISO C 99 section
5.1.2.3.(5)) ensure that we increment the actions_count only after
