[Lldb-commits] [lldb] fix: Target Process may crash or freezes on detaching process on windows (PR #115712)

[via lldb-commits]

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@@ -169,6 +169,38 @@ Status ProcessWindows::DoDetach(bool keep_stopped) {
   Log *log = GetLog(WindowsLog::Process);
   StateType private_state = GetPrivateState();
   if (private_state != eStateExited && private_state != eStateDetached) {
+    if (!keep_stopped) {
+      // if the thread is suspended by lldb, we have to resume threads before
+      // detaching process. When we do after DetachProcess(), thread handles
+      // become invalid so we do before detach.
+      if (private_state == eStateStopped || private_state == eStateCrashed) {
+        LLDB_LOG(log, "process {0} is in state {1}.  Resuming for detach...",
+                 m_session_data->m_debugger->GetProcess().GetProcessId(),
+                 GetPrivateState());
+
+        LLDB_LOG(log, "resuming {0} threads for detach.",
+                 m_thread_list.GetSize());
+
+        bool failed = false;
+        for (uint32_t i = 0; i < m_thread_list.GetSize(); ++i) {
+          auto thread = std::static_pointer_cast<TargetThreadWindows>(
+              m_thread_list.GetThreadAtIndex(i));
+          Status result = thread->DoResume();
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anatawa12 wrote:

> Does this mean that if the thread/process gets another exception before we manage to detach from it, it will remain suspended?

No, the process will not suspend.
The process will receive the exception and the process handles it instead.
For simple programs, it will crash the process but some process may handle in their way.
We can see this behavior with TestDetachResumes by reverting 5ad1a98a8b07e1d75829870995fbf36fb8cb99ed.

> I'm not familiar with windows debugging API, so I don't know if there's a way to handle this, but I believe this is the reason why linux (and others) have a PTRACE_DETACH call which (atomically) detaches from a process/thread _and_ resumes it.

I agree with that but as far as I researched I could not figure out the API to detach and resume thread simultaneously.


https://github.com/llvm/llvm-project/pull/115712