Guard against the C++ destructor chain by not letting the debugger list clean up after itself in the C++ destructor chain.

If users call "static void lldb::SBDebugger::Terminate()" we will clean up the debugger list, and users can individually destroy debugger instances with "static void lldb::SBDebugger::Destroy(SBDebugger &)". But if we let the C++ destructor chain tear down this list, other threads that might still be running as the main thread exits can now crash if they access the debugger list. We stop this by leaking the debugger list and its mutex.

<rdar://problem/26372169>

llvm-svn: 270869

1 files changed, 49 insertions, 67 deletions

diff --git a/lldb/source/Core/Debugger.cpp b/lldb/source/Core/Debugger.cpp
index d5727efe6a3..dfff06d11a9 100644
--- a/lldb/source/Core/Debugger.cpp
+++ b/lldb/source/Core/Debugger.cpp
@@ -68,23 +68,9 @@ static size_t g_debugger_event_thread_stack_bytes = 8 * 1024 * 1024;
 
 #pragma mark Static Functions
 
-static std::recursive_mutex &
-GetDebuggerListMutex()
-{
-    static std::recursive_mutex g_mutex;
-    return g_mutex;
-}
-
 typedef std::vector<DebuggerSP> DebuggerList;
-
-static DebuggerList &
-GetDebuggerList()
-{
-    // hide the static debugger list inside a singleton accessor to avoid
-    // global init constructors
-    static DebuggerList g_list;
-    return g_list;
-}
+static std::recursive_mutex *g_debugger_list_mutex_ptr = nullptr; // NOTE: intentional leak to avoid issues with C++ destructor chain
+static DebuggerList *g_debugger_list_ptr = nullptr; // NOTE: intentional leak to avoid issues with C++ destructor chain
 
 OptionEnumValueElement
 g_show_disassembly_enum_values[] =
@@ -454,28 +440,32 @@ Debugger::SetTabSize (uint32_t tab_size)
 //}
 //
 
-static bool lldb_initialized = false;
 void
 Debugger::Initialize(LoadPluginCallbackType load_plugin_callback)
 {
-    assert(!lldb_initialized && "Debugger::Initialize called more than once!");
-
-    lldb_initialized = true;
+    assert(g_debugger_list_ptr == nullptr && "Debugger::Initialize called more than once!");
+    g_debugger_list_mutex_ptr = new std::recursive_mutex();
+    g_debugger_list_ptr = new DebuggerList();
     g_load_plugin_callback = load_plugin_callback;
 }
 
 void
 Debugger::Terminate ()
 {
-    assert(lldb_initialized && "Debugger::Terminate called without a matching Debugger::Initialize!");
+    assert(g_debugger_list_ptr && "Debugger::Terminate called without a matching Debugger::Initialize!");
 
-    // Clear our master list of debugger objects
-    std::lock_guard<std::recursive_mutex> guard(GetDebuggerListMutex());
-    auto& debuggers = GetDebuggerList();
-    for (const auto& debugger: debuggers)
-        debugger->Clear();
-
-    debuggers.clear();
+    if (g_debugger_list_ptr && g_debugger_list_mutex_ptr)
+    {
+        // Clear our master list of debugger objects
+        {
+            std::lock_guard<std::recursive_mutex> guard(*g_debugger_list_mutex_ptr);
+            for (const auto& debugger: *g_debugger_list_ptr)
+                debugger->Clear();
+            g_debugger_list_ptr->clear();
+            delete g_debugger_list_ptr;
+            g_debugger_list_ptr = nullptr;
+        }
+    }
 }
 
 void
@@ -604,10 +594,10 @@ DebuggerSP
 Debugger::CreateInstance (lldb::LogOutputCallback log_callback, void *baton)
 {
     DebuggerSP debugger_sp (new Debugger(log_callback, baton));
-    if (lldb_initialized)
+    if (g_debugger_list_ptr && g_debugger_list_mutex_ptr)
     {
-        std::lock_guard<std::recursive_mutex> guard(GetDebuggerListMutex());
-        GetDebuggerList().push_back(debugger_sp);
+        std::lock_guard<std::recursive_mutex> guard(*g_debugger_list_mutex_ptr);
+        g_debugger_list_ptr->push_back(debugger_sp);
     }
     debugger_sp->InstanceInitialize ();
     return debugger_sp;
@@ -621,16 +611,15 @@ Debugger::Destroy (DebuggerSP &debugger_sp)
         
     debugger_sp->Clear();
 
-    if (lldb_initialized)
+    if (g_debugger_list_ptr && g_debugger_list_mutex_ptr)
     {
-        std::lock_guard<std::recursive_mutex> guard(GetDebuggerListMutex());
-        DebuggerList &debugger_list = GetDebuggerList ();
-        DebuggerList::iterator pos, end = debugger_list.end();
-        for (pos = debugger_list.begin (); pos != end; ++pos)
+        std::lock_guard<std::recursive_mutex> guard(*g_debugger_list_mutex_ptr);
+        DebuggerList::iterator pos, end = g_debugger_list_ptr->end();
+        for (pos = g_debugger_list_ptr->begin (); pos != end; ++pos)
         {
             if ((*pos).get() == debugger_sp.get())
             {
-                debugger_list.erase (pos);
+                g_debugger_list_ptr->erase (pos);
                 return;
             }
         }
@@ -641,13 +630,11 @@ DebuggerSP
 Debugger::FindDebuggerWithInstanceName (const ConstString &instance_name)
 {
     DebuggerSP debugger_sp;
-    if (lldb_initialized)
+    if (g_debugger_list_ptr && g_debugger_list_mutex_ptr)
     {
-        std::lock_guard<std::recursive_mutex> guard(GetDebuggerListMutex());
-        DebuggerList &debugger_list = GetDebuggerList();
-        DebuggerList::iterator pos, end = debugger_list.end();
-
-        for (pos = debugger_list.begin(); pos != end; ++pos)
+        std::lock_guard<std::recursive_mutex> guard(*g_debugger_list_mutex_ptr);
+        DebuggerList::iterator pos, end = g_debugger_list_ptr->end();
+        for (pos = g_debugger_list_ptr->begin (); pos != end; ++pos)
         {
             if ((*pos)->m_instance_name == instance_name)
             {
@@ -663,12 +650,11 @@ TargetSP
 Debugger::FindTargetWithProcessID (lldb::pid_t pid)
 {
     TargetSP target_sp;
-    if (lldb_initialized)
+    if (g_debugger_list_ptr && g_debugger_list_mutex_ptr)
     {
-        std::lock_guard<std::recursive_mutex> guard(GetDebuggerListMutex());
-        DebuggerList &debugger_list = GetDebuggerList();
-        DebuggerList::iterator pos, end = debugger_list.end();
-        for (pos = debugger_list.begin(); pos != end; ++pos)
+        std::lock_guard<std::recursive_mutex> guard(*g_debugger_list_mutex_ptr);
+        DebuggerList::iterator pos, end = g_debugger_list_ptr->end();
+        for (pos = g_debugger_list_ptr->begin (); pos != end; ++pos)
         {
             target_sp = (*pos)->GetTargetList().FindTargetWithProcessID (pid);
             if (target_sp)
@@ -682,12 +668,11 @@ TargetSP
 Debugger::FindTargetWithProcess (Process *process)
 {
     TargetSP target_sp;
-    if (lldb_initialized)
+    if (g_debugger_list_ptr && g_debugger_list_mutex_ptr)
     {
-        std::lock_guard<std::recursive_mutex> guard(GetDebuggerListMutex());
-        DebuggerList &debugger_list = GetDebuggerList();
-        DebuggerList::iterator pos, end = debugger_list.end();
-        for (pos = debugger_list.begin(); pos != end; ++pos)
+        std::lock_guard<std::recursive_mutex> guard(*g_debugger_list_mutex_ptr);
+        DebuggerList::iterator pos, end = g_debugger_list_ptr->end();
+        for (pos = g_debugger_list_ptr->begin (); pos != end; ++pos)
         {
             target_sp = (*pos)->GetTargetList().FindTargetWithProcess (process);
             if (target_sp)
@@ -1162,10 +1147,10 @@ Debugger::GetAsyncErrorStream ()
 size_t
 Debugger::GetNumDebuggers()
 {
-    if (lldb_initialized)
+    if (g_debugger_list_ptr && g_debugger_list_mutex_ptr)
     {
-        std::lock_guard<std::recursive_mutex> guard(GetDebuggerListMutex());
-        return GetDebuggerList().size();
+        std::lock_guard<std::recursive_mutex> guard(*g_debugger_list_mutex_ptr);
+        return g_debugger_list_ptr->size();
     }
     return 0;
 }
@@ -1175,13 +1160,11 @@ Debugger::GetDebuggerAtIndex (size_t index)
 {
     DebuggerSP debugger_sp;
     
-    if (lldb_initialized)
+    if (g_debugger_list_ptr && g_debugger_list_mutex_ptr)
     {
-        std::lock_guard<std::recursive_mutex> guard(GetDebuggerListMutex());
-        DebuggerList &debugger_list = GetDebuggerList();
-
-        if (index < debugger_list.size())
-            debugger_sp = debugger_list[index];
+        std::lock_guard<std::recursive_mutex> guard(*g_debugger_list_mutex_ptr);
+        if (index < g_debugger_list_ptr->size())
+            debugger_sp = g_debugger_list_ptr->at(index);
     }
 
     return debugger_sp;
@@ -1192,12 +1175,11 @@ Debugger::FindDebuggerWithID (lldb::user_id_t id)
 {
     DebuggerSP debugger_sp;
 
-    if (lldb_initialized)
+    if (g_debugger_list_ptr && g_debugger_list_mutex_ptr)
     {
-        std::lock_guard<std::recursive_mutex> guard(GetDebuggerListMutex());
-        DebuggerList &debugger_list = GetDebuggerList();
-        DebuggerList::iterator pos, end = debugger_list.end();
-        for (pos = debugger_list.begin(); pos != end; ++pos)
+        std::lock_guard<std::recursive_mutex> guard(*g_debugger_list_mutex_ptr);
+        DebuggerList::iterator pos, end = g_debugger_list_ptr->end();
+        for (pos = g_debugger_list_ptr->begin (); pos != end; ++pos)
         {
             if ((*pos)->GetID() == id)
             {