slot_base::slot_base(src): If the source slot_base has a null rep->call_,

2005-05-01  Murray Cumming <murrayc@murrayc.com>

        * sigc++/functors/slot_base.cc:
        slot_base::slot_base(src): If the source
        slot_base has a null rep->call_, meaning that the
        slot is invalid, just return a default-constructed
        slot, to prevent the crash shown in
        tests/tests_copy_invalid_slot.cc. Bug #302515 by
        Régis Duchesne.

3 files changed, 28 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index eed146c..0825c48 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,15 @@
 2005-05-01  Murray Cumming <murrayc@murrayc.com>
 
+	* sigc++/functors/slot_base.cc: 
+	slot_base::slot_base(src): If the source 
+	slot_base has a null rep->call_, meaning that the 
+	slot is invalid, just return a default-constructed 
+	slot, to prevent the crash shown in 
+	tests/tests_copy_invalid_slot.cc. Bug #302515 by 
+	Régis Duchesne.
+
+2005-05-01  Murray Cumming <murrayc@murrayc.com>
+
 	* sigc++/functors/macros/mem_fun.h.m4: bound_*<>: 
 	Add a new is_base_and_derived<sigc::trackable> 
 	parameter to the template and thereby provide a 
diff --git a/sigc++/functors/slot_base.cc b/sigc++/functors/slot_base.cc
index 6f57e74..27e37ae 100644
--- a/sigc++/functors/slot_base.cc
+++ b/sigc++/functors/slot_base.cc
@@ -55,9 +55,11 @@ void slot_rep::disconnect()
 void* slot_rep::notify(void* data)
 {
   slot_rep* self_ = reinterpret_cast<slot_rep*>(data);
+
   self_->call_ = 0; // Invalidate the slot.
   self_->destroy(); // Detach the stored functor from the other referred trackables and destroy it.
   self_->disconnect(); // Disconnect the slot (might lead to deletion of self_!).
+
   return 0;
 }
 
@@ -78,7 +80,17 @@ slot_base::slot_base(const slot_base& src)
   blocked_(src.blocked_)
 {
   if (src.rep_)
-    rep_ = src.rep_->dup();
+  {
+    //Check call_ so we can ignore invalidated slots.
+    //Otherwise, destroyed bound reference parameters (whose destruction caused the slot's invalidation) may be used during dup().
+    //Note: I'd prefer to check somewhere during dup(). murrayc.
+    if (src.rep_->call_)
+      rep_ = src.rep_->dup();
+    else
+    {
+      *this = slot_base(); //Return the default invalid slot.
+    }
+  }
 }
 
 slot_base::~slot_base()
diff --git a/tests/test_copy_invalid_slot.cc b/tests/test_copy_invalid_slot.cc
index 4739c17..40162b0 100644
--- a/tests/test_copy_invalid_slot.cc
+++ b/tests/test_copy_invalid_slot.cc
@@ -11,6 +11,11 @@ int main(int argc, char **argv)
    // This invalidates foo.
    delete t;
 
+   // Try to crash if the invalid slot parameter is used by libsigc++,
+   // and get a debugger backtrace at the point that it happens.
+   //
+   // Comment this out to get a meaningful backtrace from valgrind.
+   //
    // Try to pollute the memory previously occupied by the sigc::trackable
    // instance. The hope is that with a regular memory allocator (i.e. not
    // valgrind), we end up with buffer == (void *)t.