Fix a crash when a stop hook deletes itself in its callback. (#160416)

We're iterating over the stop hooks so if one of them changes the stop
hook list by deleting itself or another stop hook, that invalidates our
iterator.

I chose to fix this by making a copy of the stop hook list and iterating
over that. That's a cheap operation since this is just an array of
shared pointers. But more importantly doing it this way means that if on
a stop where one stop hook deletes another, the deleted hook will always
get a chance to run. If you iterated over the list itself, then whether
that to be deleted hook gets to run would be dependent on whether it was
before or after the deleting stop hook, which would be confusing.

1 files changed, 5 insertions, 0 deletions

diff --git a/lldb/source/Target/Target.cpp b/lldb/source/Target/Target.cpp
index ae6c4f719110..3b51e17d1c4e 100644
--- a/lldb/source/Target/Target.cpp
+++ b/lldb/source/Target/Target.cpp
@@ -3207,6 +3207,11 @@ bool Target::RunStopHooks(bool at_initial_stop) {
   bool should_stop = false;
   bool requested_continue = false;
 
+  // A stop hook might get deleted while running stop hooks.
+  // We have to decide what that means.  We will follow the rule that deleting
+  // a stop hook while processing these stop hooks will delete it for FUTURE
+  // stops but not this stop.  Fortunately, copying the m_stop_hooks to the
+  // active_hooks list before iterating over the hooks has this effect.
   for (auto cur_hook_sp : active_hooks) {
     bool any_thread_matched = false;
     for (auto exc_ctx : exc_ctx_with_reasons) {