1 files changed, 132 insertions, 4 deletions
diff --git a/libstdc++-v3/libsupc++/guard.cc b/libstdc++-v3/libsupc++/guard.cc
index 255108f..a9280bc 100644
--- a/libstdc++-v3/libsupc++/guard.cc
+++ b/libstdc++-v3/libsupc++/guard.cc
@@ -29,26 +29,154 @@
 // Written by Mark Mitchell, CodeSourcery LLC, <mark@codesourcery.com>
 
 #include <cxxabi.h>
+#include <exception>
+#include <bits/c++config.h>
+#include <bits/gthr.h>
 
 // The IA64/generic ABI uses the first byte of the guard variable.
 // The ARM EABI uses the least significant bit.
 
+// Thread-safe static local initialization support.
+#ifdef __GTHREADS
+namespace
+{
+  // static_mutex is a single mutex controlling all static initializations.
+  // This is a static class--the need for a static initialization function
+  // to pass to __gthread_once precludes creating multiple instances, though
+  // I suppose you could achieve the same effect with a template.
+  class static_mutex
+  {
+    static __gthread_recursive_mutex_t mutex;
+
+#ifdef __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION
+    static void init();
+#endif
+
+  public:
+    static void lock();
+    static void unlock();
+  };
+
+  __gthread_recursive_mutex_t static_mutex::mutex
+#ifdef __GTHREAD_RECURSIVE_MUTEX_INIT
+  = __GTHREAD_RECURSIVE_MUTEX_INIT
+#endif
+  ;
+
+#ifdef __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION
+  void static_mutex::init()
+  {
+    __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION (&mutex);
+  }
+#endif
+
+  void static_mutex::lock()
+  {
+#ifdef __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION
+    static __gthread_once_t once = __GTHREAD_ONCE_INIT;
+    __gthread_once (&once, init);
+#endif
+    __gthread_recursive_mutex_lock (&mutex);
+  }
+
+  void static_mutex::unlock ()
+  {
+    __gthread_recursive_mutex_unlock (&mutex);
+  }
+}
+#endif
+
+namespace __gnu_cxx
+{
+  // 6.7[stmt.dcl]/4: If control re-enters the declaration (recursively)
+  // while the object is being initialized, the behavior is undefined.
+
+  // Since we already have a library function to handle locking, we might
+  // as well check for this situation and throw an exception.
+  // We use the second byte of the guard variable to remember that we're
+  // in the middle of an initialization.
+  class recursive_init: public std::exception
+  {
+  public:
+    recursive_init() throw() { }
+    virtual ~recursive_init() throw ();
+  };
+
+  recursive_init::~recursive_init() throw() { }
+}
+
 namespace __cxxabiv1 
 {
+  static int
+  acquire_1 (__guard *g)
+  {
+    if (_GLIBCXX_GUARD_ACQUIRE (g))
+      {
+	if (((char *)g)[1]++)
+	  {
+#ifdef __EXCEPTIONS
+	    throw __gnu_cxx::recursive_init();
+#else
+	    abort ();
+#endif
+	  }
+	return 1;
+      }
+    return 0;
+  }
+  
   extern "C"
   int __cxa_guard_acquire (__guard *g) 
   {
-    return _GLIBCXX_GUARD_ACQUIRE (g);
+#ifdef __GTHREADS
+    if (__gthread_active_p ())
+      {
+	// Simple wrapper for exception safety.
+	struct mutex_wrapper
+	{
+	  bool unlock;
+	  mutex_wrapper (): unlock(true)
+	  {
+	    static_mutex::lock ();
+	  }
+	  ~mutex_wrapper ()
+	  {
+	    if (unlock)
+	      static_mutex::unlock ();
+	  }
+	} mw;
+
+	if (acquire_1 (g))
+	  {
+	    mw.unlock = false;
+	    return 1;
+	  }
+
+	return 0;
+      }
+#endif
+
+    return acquire_1 (g);
   }
 
   extern "C"
-  void __cxa_guard_release (__guard *g)
+  void __cxa_guard_abort (__guard *g)
   {
-    _GLIBCXX_GUARD_RELEASE (g);
+    ((char *)g)[1]--;
+#ifdef __GTHREADS
+    if (__gthread_active_p ())
+      static_mutex::unlock ();
+#endif
   }
 
   extern "C"
-  void __cxa_guard_abort (__guard *)
+  void __cxa_guard_release (__guard *g)
   {
+    ((char *)g)[1]--;
+    _GLIBCXX_GUARD_RELEASE (g);
+#ifdef __GTHREADS
+    if (__gthread_active_p ())
+      static_mutex::unlock ();
+#endif
   }
 }