[RFC][PATCH v1 2/5] include/link.h: Update the link_map struct to allow clones

[Vivek Das Mohapatra <vivek at collabora dot com>]

From: Vivek Das Mohapatra <vivek@collabora.co.uk>

We already have an l_real pointer, used for a similar purpose by
the linker for copies of ld.so in secondary namespaces. Update its
documentation and add a bitfield to indicate when link_map entry
is a clone.
---
 include/link.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/link.h b/include/link.h
index 5924594548..e051b5cd36 100644
--- a/include/link.h
+++ b/include/link.h
@@ -104,8 +104,9 @@ struct link_map
        They may change without notice.  */
 
     /* This is an element which is only ever different from a pointer to
-       the very same copy of this type for ld.so when it is used in more
-       than one namespace.  */
+       the very same copy of this type when:
+       - A shallow copy of ld.so is placed in namespaces other than LM_ID_BASE.
+       - An object is cloned into a namespace by dlmopen with RTLD_SHARED.  */
     struct link_map *l_real;
 
     /* Number of the namespace this link map belongs to.  */
@@ -177,6 +178,7 @@ struct link_map
     unsigned int l_relocated:1;	/* Nonzero if object's relocations done.  */
     unsigned int l_init_called:1; /* Nonzero if DT_INIT function called.  */
     unsigned int l_global:1;	/* Nonzero if object in _dl_global_scope.  */
+    unsigned int l_clone:1;    /* Nonzero if object is a clone.  */
     unsigned int l_reserved:2;	/* Reserved for internal use.  */
     unsigned int l_phdr_allocated:1; /* Nonzero if the data structure pointed
 					to by `l_phdr' is allocated.  */
-- 
2.11.0