2 files changed, 63 insertions, 44 deletions

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 59b6c63a..700c166d 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,11 @@
+2013-06-26  Mark Wielaard  <mjw@redhat.com>
+
+	* libdw_visit_scopes.c (__libdw_visit_scopes): Don't reject root
+	DIEs without children. Return an error whenever dwarf_child or
+	dwarf_siblingof return an error. Don't call recurse and increase
+	the depth for an imported unit. Walk the children of an imported
+	unit as if they are logical children of the parent root DIE.
+
 2013-05-03  Mark Wielaard  <mjw@redhat.com>
 
 	* dwarf_getsrclines.c (dwarf_getsrclines): Only set end_sequence
diff --git a/libdw/libdw_visit_scopes.c b/libdw/libdw_visit_scopes.c
index ea0c6b47..a8555ce4 100644
--- a/libdw/libdw_visit_scopes.c
+++ b/libdw/libdw_visit_scopes.c
@@ -84,10 +84,11 @@ __libdw_visit_scopes (depth, root, previsit, postvisit, arg)
      void *arg;
 {
   struct Dwarf_Die_Chain child;
+  int ret;
 
   child.parent = root;
-  if (INTUSE(dwarf_child) (&root->die, &child.die) != 0)
-    return -1;
+  if ((ret = INTUSE(dwarf_child) (&root->die, &child.die)) != 0)
+    return ret < 0 ? -1 : 0; // Having zero children is legal.
 
   inline int recurse (void)
     {
@@ -95,63 +96,73 @@ __libdw_visit_scopes (depth, root, previsit, postvisit, arg)
 				   previsit, postvisit, arg);
     }
 
-  do
-    {
-      child.prune = false;
-
-      if (previsit != NULL)
-	{
-	  int result = (*previsit) (depth + 1, &child, arg);
-	  if (result != DWARF_CB_OK)
-	    return result;
-	}
-
-      if (!child.prune)
-	switch (classify_die (&child.die))
+  inline int walk_children ()
+  {
+    do
+      {
+	/* For an imported unit, it is logically as if the children of
+	   that unit are siblings of the other children.  So don't do
+	   a full recursion into the imported unit, but just walk the
+	   children in place before moving to the next real child.  */
+	while (classify_die (&child.die) == imported)
 	  {
-	  case match:
-	  case match_inline:
-	  case walk:
-	    if (INTUSE(dwarf_haschildren) (&child.die))
+	    Dwarf_Die orig_child_die = child.die;
+	    Dwarf_Attribute attr_mem;
+	    Dwarf_Attribute *attr = INTUSE(dwarf_attr) (&child.die,
+							DW_AT_import,
+							&attr_mem);
+	    if (INTUSE(dwarf_formref_die) (attr, &child.die) != NULL
+                && INTUSE(dwarf_child) (&child.die, &child.die) == 0)
 	      {
-		int result = recurse ();
+		int result = walk_children ();
 		if (result != DWARF_CB_OK)
 		  return result;
 	      }
-	    break;
 
-	  case imported:
+	    /* Any "real" children left?  */
+	    if ((ret = INTUSE(dwarf_siblingof) (&orig_child_die,
+						&child.die)) != 0)
+	      return ret < 0 ? -1 : 0;
+	  };
+
+	child.prune = false;
+
+	if (previsit != NULL)
+	  {
+	    int result = (*previsit) (depth + 1, &child, arg);
+	    if (result != DWARF_CB_OK)
+	      return result;
+	  }
+
+	if (!child.prune)
+	  switch (classify_die (&child.die))
 	    {
-	      /* This imports another compilation unit to appear
-		 as part of this one, inside the current scope.
-		 Recurse to search the referenced unit, but without
-		 recording it as an inner scoping level.  */
-
-	      Dwarf_Attribute attr_mem;
-	      Dwarf_Attribute *attr = INTUSE(dwarf_attr) (&child.die,
-							  DW_AT_import,
-							  &attr_mem);
-	      if (INTUSE(dwarf_formref_die) (attr, &child.die) != NULL)
+	    case match:
+	    case match_inline:
+	    case walk:
+	      if (INTUSE(dwarf_haschildren) (&child.die))
 		{
 		  int result = recurse ();
 		  if (result != DWARF_CB_OK)
 		    return result;
 		}
+	      break;
+
+	    default:
+	      break;
 	    }
-	    break;
 
-	  default:
-	    break;
+	if (postvisit != NULL)
+	  {
+	    int result = (*postvisit) (depth + 1, &child, arg);
+	    if (result != DWARF_CB_OK)
+	      return result;
 	  }
+      }
+    while ((ret = INTUSE(dwarf_siblingof) (&child.die, &child.die)) == 0);
 
-      if (postvisit != NULL)
-	{
-	  int result = (*postvisit) (depth + 1, &child, arg);
-	  if (result != DWARF_CB_OK)
-	    return result;
-	}
-    }
-  while (INTUSE(dwarf_siblingof) (&child.die, &child.die) == 0);
+    return ret < 0 ? -1 : 0;
+  }
 
-  return 0;
+  return walk_children ();
 }