37 files changed, 353 insertions, 154 deletions

diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index a605bc5..9c4c47c 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -142,8 +142,11 @@ Bug Fixes since HDF5-1.8.0 release
 
     Library
     -------
-      - Fixed a bug that could cause problems when copying an object with a shared
-            message in its own object header. (NAF - 2009/01/29)
+      - Fixed a bug that could cause problems when an attribute was added to a
+            committed datatype using the committed datatype's datatype.
+            (NAF - 2009/02/12)
+      - Fixed a bug that could cause problems when copying an object with a
+            shared message in its own object header. (NAF - 2009/01/29)
       - Changed H5Tset_order to properly reject H5T_ORDER_NONE for most
             datatypes. (NAF - 2009/01/27)
       - Fixed a bug where H5Tpack wouldn't remove trailing space from an
diff --git a/src/H5Abtree2.c b/src/H5Abtree2.c
index 07550da..da4ad86 100644
--- a/src/H5Abtree2.c
+++ b/src/H5Abtree2.c
@@ -168,7 +168,7 @@ H5A_dense_fh_name_cmp(const void *obj, size_t UNUSED obj_len, void *_udata)
     FUNC_ENTER_NOAPI_NOINIT(H5A_dense_fh_name_cmp)
 
     /* Decode attribute information */
-    if(NULL == (attr = (H5A_t *)H5O_msg_decode(udata->f, udata->dxpl_id, H5O_ATTR_ID, (const unsigned char *)obj)))
+    if(NULL == (attr = (H5A_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_ATTR_ID, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, FAIL, "can't decode attribute")
 
     /* Compare the string values */
diff --git a/src/H5Adense.c b/src/H5Adense.c
index 76ab95d..bc5ddfb 100644
--- a/src/H5Adense.c
+++ b/src/H5Adense.c
@@ -806,7 +806,7 @@ H5A_dense_copy_fh_cb(const void *obj, size_t UNUSED obj_len, void *_udata)
      *  HDF5 routine, it could attempt to re-protect that direct block for the
      *  heap, causing the HDF5 routine called to fail)
      */
-    if(NULL == (udata->attr = (H5A_t *)H5O_msg_decode(udata->f, udata->dxpl_id, H5O_ATTR_ID, (const unsigned char *)obj)))
+    if(NULL == (udata->attr = (H5A_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_ATTR_ID, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTDECODE, FAIL, "can't decode attribute")
 
     /* Set the creation order index for the attribute */
diff --git a/src/H5Gbtree2.c b/src/H5Gbtree2.c
index d060a11..c16fc16 100644
--- a/src/H5Gbtree2.c
+++ b/src/H5Gbtree2.c
@@ -164,7 +164,7 @@ H5G_dense_fh_name_cmp(const void *obj, size_t UNUSED obj_len, void *_udata)
     FUNC_ENTER_NOAPI_NOINIT(H5G_dense_fh_name_cmp)
 
     /* Decode link information */
-    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode link")
 
     /* Compare the string values */
diff --git a/src/H5Gdense.c b/src/H5Gdense.c
index 6c3a171..2bca4fa 100644
--- a/src/H5Gdense.c
+++ b/src/H5Gdense.c
@@ -566,7 +566,7 @@ H5G_dense_lookup_by_idx_fh_cb(const void *obj, size_t UNUSED obj_len, void *_uda
     FUNC_ENTER_NOAPI_NOINIT(H5G_dense_lookup_by_idx_fh_cb)
 
     /* Decode link information & keep a copy */
-    if(NULL == (tmp_lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (tmp_lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode link")
 
     /* Copy link information */
@@ -852,7 +852,7 @@ H5G_dense_iterate_fh_cb(const void *obj, size_t UNUSED obj_len, void *_udata)
      *  HDF5 routine, it could attempt to re-protect that direct block for the
      *  heap, causing the HDF5 routine called to fail - QAK)
      */
-    if(NULL == (udata->lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (udata->lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode link")
 
 done:
@@ -1047,7 +1047,7 @@ H5G_dense_get_name_by_idx_fh_cb(const void *obj, size_t UNUSED obj_len, void *_u
     FUNC_ENTER_NOAPI_NOINIT(H5G_dense_get_name_by_idx_fh_cb)
 
     /* Decode link information */
-    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode link")
 
     /* Get the length of the name */
@@ -1245,7 +1245,7 @@ H5G_dense_remove_fh_cb(const void *obj, size_t UNUSED obj_len, void *_udata)
     FUNC_ENTER_NOAPI_NOINIT(H5G_dense_remove_fh_cb)
 
     /* Decode link information */
-    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode link")
 
     /* Check for removing the link from the creation order index */
@@ -1408,7 +1408,7 @@ H5G_dense_remove_by_idx_fh_cb(const void *obj, size_t UNUSED obj_len, void *_uda
     FUNC_ENTER_NOAPI_NOINIT(H5G_dense_remove_by_idx_fh_cb)
 
     /* Decode link information */
-    if(NULL == (udata->lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (udata->lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, H5_ITER_ERROR, "can't decode link")
 
     /* Can't operate on link here because the fractal heap block is locked */
diff --git a/src/H5HFcache.c b/src/H5HFcache.c
index 847c54e..8ab35cb 100644
--- a/src/H5HFcache.c
+++ b/src/H5HFcache.c
@@ -387,7 +387,7 @@ HDfprintf(stderr, "%s: Load heap header, addr = %a\n", FUNC, addr);
         UINT32DECODE(p, hdr->pline_root_direct_filter_mask);
 
         /* Decode I/O filter information */
-        if(NULL == (pline = (H5O_pline_t *)H5O_msg_decode(hdr->f, dxpl_id, H5O_PLINE_ID, p)))
+        if(NULL == (pline = (H5O_pline_t *)H5O_msg_decode(hdr->f, dxpl_id, NULL, H5O_PLINE_ID, p)))
             HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, NULL, "can't decode I/O pipeline filters")
         p += hdr->filter_len;
 
diff --git a/src/H5O.c b/src/H5O.c
index 73c8e73..8c8ace0 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -1393,9 +1393,9 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5O_link
+ * Function:	H5O_link_oh
  *
- * Purpose:	Adjust the link count for an object header by adding
+ * Purpose:	Adjust the link count for an open object header by adding
  *		ADJUST to the link count.
  *
  * Return:	Success:	New link count
@@ -1409,24 +1409,12 @@ done:
  *-------------------------------------------------------------------------
  */
 int
-H5O_link(const H5O_loc_t *loc, int adjust, hid_t dxpl_id)
+H5O_link_oh(H5F_t *f, int adjust, hid_t dxpl_id, H5O_t *oh, unsigned *oh_flags)
 {
-    H5O_t	*oh = NULL;
-    H5AC_protect_t oh_acc;              /* Access mode for protecting object header */
-    unsigned oh_flags = H5AC__NO_FLAGS_SET; /* Whether the object was deleted  */
+    haddr_t addr = H5O_OH_GET_ADDR(oh);     /* Object header address */
     int	ret_value;                          /* Return value */
 
-    FUNC_ENTER_NOAPI(H5O_link, FAIL)
-
-    /* check args */
-    HDassert(loc);
-    HDassert(loc->file);
-    HDassert(H5F_addr_defined(loc->addr));
-
-    /* get header */
-    oh_acc = adjust ? H5AC_WRITE : H5AC_READ;
-    if(NULL == (oh = (H5O_t *)H5AC_protect(loc->file, dxpl_id, H5AC_OHDR, loc->addr, NULL, NULL, oh_acc)))
-	HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, FAIL, "unable to load object header")
+    FUNC_ENTER_NOAPI(H5O_link_oh, FAIL)
 
     /* Check for adjusting link count */
     if(adjust) {
@@ -1435,38 +1423,38 @@ H5O_link(const H5O_loc_t *loc, int adjust, hid_t dxpl_id)
             if((unsigned)(-adjust) > oh->nlink)
                 HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "link count would be negative")
             oh->nlink += adjust;
-            oh_flags |= H5AC__DIRTIED_FLAG;
+            *oh_flags |= H5AC__DIRTIED_FLAG;
 
             /* Check if the object should be deleted */
             if(oh->nlink == 0) {
                 /* Check if the object is still open by the user */
-                if(H5FO_opened(loc->file, loc->addr) != NULL) {
+                if(H5FO_opened(f, addr) != NULL) {
                     /* Flag the object to be deleted when it's closed */
-                    if(H5FO_mark(loc->file, loc->addr, TRUE) < 0)
+                    if(H5FO_mark(f, addr, TRUE) < 0)
                         HGOTO_ERROR(H5E_OHDR, H5E_CANTDELETE, FAIL, "can't mark object for deletion")
                 } /* end if */
                 else {
                     /* Delete object right now */
-                    if(H5O_delete_oh(loc->file, dxpl_id, oh) < 0)
+                    if(H5O_delete_oh(f, dxpl_id, oh) < 0)
                         HGOTO_ERROR(H5E_OHDR, H5E_CANTDELETE, FAIL, "can't delete object from file")
 
                     /* Mark the object header as deleted */
-                    oh_flags = H5AC__DELETED_FLAG | H5AC__FREE_FILE_SPACE_FLAG;
+                    *oh_flags = H5AC__DELETED_FLAG | H5AC__FREE_FILE_SPACE_FLAG;
                 } /* end else */
             } /* end if */
         } else {
             /* A new object, or one that will be deleted */
             if(oh->nlink == 0) {
                 /* Check if the object is current open, but marked for deletion */
-                if(H5FO_marked(loc->file, loc->addr) > 0) {
+                if(H5FO_marked(f, addr) > 0) {
                     /* Remove "delete me" flag on the object */
-                    if(H5FO_mark(loc->file, loc->addr, FALSE) < 0)
+                    if(H5FO_mark(f, addr, FALSE) < 0)
                         HGOTO_ERROR(H5E_OHDR, H5E_CANTDELETE, FAIL, "can't mark object for deletion")
                 } /* end if */
             } /* end if */
 
             oh->nlink += adjust;
-            oh_flags |= H5AC__DIRTIED_FLAG;
+            *oh_flags |= H5AC__DIRTIED_FLAG;
         } /* end if */
 
         /* Check for operations on refcount message */
@@ -1475,7 +1463,7 @@ H5O_link(const H5O_loc_t *loc, int adjust, hid_t dxpl_id)
             if(oh->has_refcount_msg) {
                 /* Check for removing refcount message */
                 if(oh->nlink <= 1) {
-                    if(H5O_msg_remove_real(loc->file, oh, H5O_MSG_REFCOUNT, H5O_ALL, NULL, NULL, TRUE, dxpl_id) < 0)
+                    if(H5O_msg_remove_real(f, oh, H5O_MSG_REFCOUNT, H5O_ALL, NULL, NULL, TRUE, dxpl_id) < 0)
                         HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete refcount message")
                     oh->has_refcount_msg = FALSE;
                 } /* end if */
@@ -1483,7 +1471,7 @@ H5O_link(const H5O_loc_t *loc, int adjust, hid_t dxpl_id)
                 else {
                     H5O_refcount_t refcount = oh->nlink;
 
-                    if(H5O_msg_write_real(loc->file, dxpl_id, oh, H5O_MSG_REFCOUNT, H5O_MSG_FLAG_DONTSHARE, 0, &refcount) < 0)
+                    if(H5O_msg_write_real(f, dxpl_id, oh, H5O_MSG_REFCOUNT, H5O_MSG_FLAG_DONTSHARE, 0, &refcount) < 0)
                         HGOTO_ERROR(H5E_ATTR, H5E_CANTUPDATE, FAIL, "unable to update refcount message")
                 } /* end else */
             } /* end if */
@@ -1492,7 +1480,7 @@ H5O_link(const H5O_loc_t *loc, int adjust, hid_t dxpl_id)
                 if(oh->nlink > 1) {
                     H5O_refcount_t refcount = oh->nlink;
 
-                    if(H5O_msg_append_real(loc->file, dxpl_id, oh, H5O_MSG_REFCOUNT, H5O_MSG_FLAG_DONTSHARE, 0, &refcount) < 0)
+                    if(H5O_msg_append_real(f, dxpl_id, oh, H5O_MSG_REFCOUNT, H5O_MSG_FLAG_DONTSHARE, 0, &refcount) < 0)
                         HGOTO_ERROR(H5E_ATTR, H5E_CANTINSERT, FAIL, "unable to create new refcount message")
                     oh->has_refcount_msg = TRUE;
                 } /* end if */
@@ -1504,6 +1492,51 @@ H5O_link(const H5O_loc_t *loc, int adjust, hid_t dxpl_id)
     ret_value = oh->nlink;
 
 done:
+    FUNC_LEAVE_NOAPI(ret_value);
+} /* end H5O_link_oh() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5O_link
+ *
+ * Purpose:	Adjust the link count for an object header by adding
+ *		ADJUST to the link count.
+ *
+ * Return:	Success:	New link count
+ *
+ *		Failure:	Negative
+ *
+ * Programmer:	Robb Matzke
+ *		matzke@llnl.gov
+ *		Aug  5 1997
+ *
+ *-------------------------------------------------------------------------
+ */
+int
+H5O_link(const H5O_loc_t *loc, int adjust, hid_t dxpl_id)
+{
+    H5O_t	*oh = NULL;
+    H5AC_protect_t oh_acc;              /* Access mode for protecting object header */
+    unsigned oh_flags = H5AC__NO_FLAGS_SET; /* Whether the object was deleted  */
+    int	ret_value;                          /* Return value */
+
+    FUNC_ENTER_NOAPI(H5O_link, FAIL)
+
+    /* check args */
+    HDassert(loc);
+    HDassert(loc->file);
+    HDassert(H5F_addr_defined(loc->addr));
+
+    /* get header */
+    oh_acc = adjust ? H5AC_WRITE : H5AC_READ;
+    if(NULL == (oh = (H5O_t *)H5AC_protect(loc->file, dxpl_id, H5AC_OHDR, loc->addr, NULL, NULL, oh_acc)))
+	HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, FAIL, "unable to load object header")
+
+    /* Call the "real" link routine */
+    if((ret_value = H5O_link_oh(loc->file, adjust, dxpl_id, oh, &oh_flags)) < 0)
+        HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "unable to adjust object link count")
+
+done:
     if(oh && H5AC_unprotect(loc->file, dxpl_id, H5AC_OHDR, loc->addr, oh, oh_flags) < 0)
 	HDONE_ERROR(H5E_OHDR, H5E_PROTECT, FAIL, "unable to release object header")
 
diff --git a/src/H5Oainfo.c b/src/H5Oainfo.c
index 7f6a55d..667f28c 100644
--- a/src/H5Oainfo.c
+++ b/src/H5Oainfo.c
@@ -35,8 +35,8 @@
 
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_ainfo_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_ainfo_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_ainfo_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_ainfo_copy(const void *_mesg, void *_dest);
 static size_t H5O_ainfo_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -105,8 +105,8 @@ H5FL_DEFINE_STATIC(H5O_ainfo_t);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_ainfo_decode(H5F_t *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_ainfo_decode(H5F_t *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_ainfo_t	*ainfo = NULL;  /* Attribute info */
     unsigned char flags;        /* Flags for encoding attribute info */
diff --git a/src/H5Oattr.c b/src/H5Oattr.c
index b875d02..b375791 100644
--- a/src/H5Oattr.c
+++ b/src/H5Oattr.c
@@ -27,8 +27,8 @@
 
 /* PRIVATE PROTOTYPES */
 static herr_t H5O_attr_encode(H5F_t *f, uint8_t *p, const void *mesg);
-static void *H5O_attr_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_attr_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static void *H5O_attr_copy(const void *_mesg, void *_dest);
 static size_t H5O_attr_size(const H5F_t *f, const void *_mesg);
 static herr_t H5O_attr_free(void *mesg);
@@ -121,7 +121,7 @@ H5FL_EXTERN(H5S_extent_t);
     function using malloc() and is returned to the caller.
 --------------------------------------------------------------------------*/
 static void *
-H5O_attr_decode(H5F_t *f, hid_t dxpl_id, unsigned UNUSED mesg_flags,
+H5O_attr_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned UNUSED mesg_flags,
     unsigned *ioflags, const uint8_t *p)
 {
     H5A_t		*attr = NULL;
@@ -182,7 +182,8 @@ H5O_attr_decode(H5F_t *f, hid_t dxpl_id, unsigned UNUSED mesg_flags,
         p += name_len;    /* advance the memory pointer */
 
     /* Decode the attribute's datatype */
-    if(NULL == (attr->shared->dt = (H5T_t *)(H5O_MSG_DTYPE->decode)(f, dxpl_id, ((flags & H5O_ATTR_FLAG_TYPE_SHARED) ? H5O_MSG_FLAG_SHARED : 0), ioflags, p)))
+    if(NULL == (attr->shared->dt = (H5T_t *)(H5O_MSG_DTYPE->decode)(f, dxpl_id, open_oh,
+        ((flags & H5O_ATTR_FLAG_TYPE_SHARED) ? H5O_MSG_FLAG_SHARED : 0), ioflags, p)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTDECODE, NULL, "can't decode attribute datatype")
     if(attr->shared->version < H5O_ATTR_VERSION_2)
         p += H5O_ALIGN_OLD(attr->shared->dt_size);
@@ -196,7 +197,8 @@ H5O_attr_decode(H5F_t *f, hid_t dxpl_id, unsigned UNUSED mesg_flags,
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
     /* Decode attribute's dataspace extent */
-    if((extent = (H5S_extent_t *)(H5O_MSG_SDSPACE->decode)(f, dxpl_id, ((flags & H5O_ATTR_FLAG_SPACE_SHARED) ? H5O_MSG_FLAG_SHARED : 0), ioflags, p)) == NULL)
+    if((extent = (H5S_extent_t *)(H5O_MSG_SDSPACE->decode)(f, dxpl_id, open_oh,
+        ((flags & H5O_ATTR_FLAG_SPACE_SHARED) ? H5O_MSG_FLAG_SHARED : 0), ioflags, p)) == NULL)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTDECODE, NULL, "can't decode attribute dataspace")
 
     /* Copy the extent information to the dataspace */
diff --git a/src/H5Obogus.c b/src/H5Obogus.c
index c257ca4..cee3199 100644
--- a/src/H5Obogus.c
+++ b/src/H5Obogus.c
@@ -38,8 +38,8 @@
 #ifdef H5O_ENABLE_BOGUS
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_bogus_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_bogus_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_bogus_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static size_t H5O_bogus_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
 static herr_t H5O_bogus_debug(H5F_t *f, hid_t dxpl_id, const void *_mesg, FILE * stream,
@@ -87,8 +87,8 @@ const H5O_msg_class_t H5O_MSG_BOGUS[1] = {{
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_bogus_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_bogus_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_bogus_t *mesg = NULL;
     void *ret_value;            /* Return value */
diff --git a/src/H5Obtreek.c b/src/H5Obtreek.c
index 36e4c1a..99e6bdd 100644
--- a/src/H5Obtreek.c
+++ b/src/H5Obtreek.c
@@ -28,8 +28,8 @@
 #include "H5Opkg.h"             /* Object headers			*/
 #include "H5MMprivate.h"	/* Memory management			*/
 
-static void  *H5O_btreek_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void  *H5O_btreek_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_btreek_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void  *H5O_btreek_copy(const void *_mesg, void *_dest);
 static size_t H5O_btreek_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -79,8 +79,8 @@ const H5O_msg_class_t H5O_MSG_BTREEK[1] = {{
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_btreek_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_btreek_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_btreek_t	*mesg;          /* Native message */
     void                *ret_value;     /* Return value */
diff --git a/src/H5Ocache.c b/src/H5Ocache.c
index db093a4..551eca8 100644
--- a/src/H5Ocache.c
+++ b/src/H5Ocache.c
@@ -536,7 +536,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
                 unsigned ioflags = 0;   /* Flags for decode routine */
 
                 /* Decode continuation message */
-                cont = (H5O_cont_t *)(H5O_MSG_CONT->decode)(f, dxpl_id, 0, &ioflags, oh->mesg[curmesg].raw);
+                cont = (H5O_cont_t *)(H5O_MSG_CONT->decode)(f, dxpl_id, NULL, 0, &ioflags, oh->mesg[curmesg].raw);
                 cont->chunkno = oh->nchunks;	/*the next chunk to allocate */
 
                 /* Save 'native' form of continuation message */
@@ -559,7 +559,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
 
                 /* Decode ref. count message */
                 HDassert(oh->version > H5O_VERSION_1);
-                refcount = (H5O_refcount_t *)(H5O_MSG_REFCOUNT->decode)(f, dxpl_id, 0, &ioflags, oh->mesg[curmesg].raw);
+                refcount = (H5O_refcount_t *)(H5O_MSG_REFCOUNT->decode)(f, dxpl_id, NULL, 0, &ioflags, oh->mesg[curmesg].raw);
 
                 /* Save 'native' form of ref. count message */
                 oh->mesg[curmesg].native = refcount;
diff --git a/src/H5Ocont.c b/src/H5Ocont.c
index b3f178d..df336dd 100644
--- a/src/H5Ocont.c
+++ b/src/H5Ocont.c
@@ -37,8 +37,8 @@
 
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_cont_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_cont_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_cont_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static size_t H5O_cont_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
 static herr_t H5O_cont_free(void *mesg);
@@ -90,8 +90,8 @@ H5FL_DEFINE(H5O_cont_t);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_cont_decode(H5F_t *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_cont_decode(H5F_t *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_cont_t             *cont = NULL;
     void                   *ret_value;
diff --git a/src/H5Odrvinfo.c b/src/H5Odrvinfo.c
index 9aafe41..864fe9e 100644
--- a/src/H5Odrvinfo.c
+++ b/src/H5Odrvinfo.c
@@ -28,8 +28,8 @@
 #include "H5Opkg.h"             /* Object headers			*/
 #include "H5MMprivate.h"	/* Memory management			*/
 
-static void  *H5O_drvinfo_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void  *H5O_drvinfo_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_drvinfo_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void  *H5O_drvinfo_copy(const void *_mesg, void *_dest);
 static size_t H5O_drvinfo_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -80,8 +80,8 @@ const H5O_msg_class_t H5O_MSG_DRVINFO[1] = {{
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_drvinfo_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_drvinfo_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_drvinfo_t	*mesg;          /* Native message */
     void                *ret_value;     /* Return value */
diff --git a/src/H5Odtype.c b/src/H5Odtype.c
index 71692c1..24e443c 100644
--- a/src/H5Odtype.c
+++ b/src/H5Odtype.c
@@ -29,8 +29,8 @@
 
 /* PRIVATE PROTOTYPES */
 static herr_t H5O_dtype_encode(H5F_t *f, uint8_t *p, const void *mesg);
-static void *H5O_dtype_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_dtype_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static void *H5O_dtype_copy(const void *_mesg, void *_dest);
 static size_t H5O_dtype_size(const H5F_t *f, const void *_mesg);
 static herr_t H5O_dtype_reset(void *_mesg);
@@ -990,7 +990,7 @@ done:
     function using malloc() and is returned to the caller.
 --------------------------------------------------------------------------*/
 static void *
-H5O_dtype_decode(H5F_t *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
+H5O_dtype_decode(H5F_t *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh, unsigned UNUSED mesg_flags,
     unsigned *ioflags/*in,out*/, const uint8_t *p)
 {
     H5T_t	*dt = NULL;
diff --git a/src/H5Oefl.c b/src/H5Oefl.c
index ee51e1c..5702b34 100644
--- a/src/H5Oefl.c
+++ b/src/H5Oefl.c
@@ -29,8 +29,8 @@
 #include "H5Opkg.h"             /* Object headers			*/
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_efl_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_efl_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_efl_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_efl_copy(const void *_mesg, void *_dest);
 static size_t H5O_efl_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -84,8 +84,8 @@ const H5O_msg_class_t H5O_MSG_EFL[1] = {{
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_efl_decode(H5F_t *f, hid_t dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_efl_decode(H5F_t *f, hid_t dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_efl_t		*mesg = NULL;
     int			version;
diff --git a/src/H5Ofill.c b/src/H5Ofill.c
index 02706ec..d5345aa 100644
--- a/src/H5Ofill.c
+++ b/src/H5Ofill.c
@@ -33,12 +33,12 @@
 #include "H5Sprivate.h"		/* Dataspaces				*/
 
 
-static void  *H5O_fill_old_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void  *H5O_fill_old_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_fill_old_encode(H5F_t *f, uint8_t *p, const void *_mesg);
 static size_t H5O_fill_old_size(const H5F_t *f, const void *_mesg);
-static void  *H5O_fill_new_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void  *H5O_fill_new_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_fill_new_encode(H5F_t *f, uint8_t *p, const void *_mesg);
 static size_t H5O_fill_new_size(const H5F_t *f, const void *_mesg);
 static void  *H5O_fill_copy(const void *_mesg, void *_dest);
@@ -182,8 +182,8 @@ H5FL_BLK_EXTERN(type_conv);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_fill_new_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_fill_new_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_fill_t	*fill = NULL;
     void	*ret_value;
@@ -296,8 +296,8 @@ done:
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_fill_old_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_fill_old_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_fill_t *fill = NULL;		/* Decoded fill value message */
     void *ret_value;                    /* Return value */
diff --git a/src/H5Oginfo.c b/src/H5Oginfo.c
index 2323fff..83a6085 100644
--- a/src/H5Oginfo.c
+++ b/src/H5Oginfo.c
@@ -33,8 +33,8 @@
 
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_ginfo_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_ginfo_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_ginfo_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_ginfo_copy(const void *_mesg, void *_dest);
 static size_t H5O_ginfo_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -95,8 +95,8 @@ H5FL_DEFINE_STATIC(H5O_ginfo_t);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_ginfo_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_ginfo_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_ginfo_t         *ginfo = NULL;  /* Pointer to group information message */
     unsigned char       flags;          /* Flags for encoding group info */
diff --git a/src/H5Olayout.c b/src/H5Olayout.c
index f914006..73d2c81 100644
--- a/src/H5Olayout.c
+++ b/src/H5Olayout.c
@@ -33,8 +33,8 @@
 
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_layout_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_layout_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_layout_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_layout_copy(const void *_mesg, void *_dest);
 static size_t H5O_layout_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -93,8 +93,8 @@ H5FL_DEFINE(H5O_layout_t);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_layout_decode(H5F_t *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_layout_decode(H5F_t *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_layout_t           *mesg = NULL;
     unsigned               u;
diff --git a/src/H5Olinfo.c b/src/H5Olinfo.c
index d1eb2c0..5ba237a 100644
--- a/src/H5Olinfo.c
+++ b/src/H5Olinfo.c
@@ -35,8 +35,8 @@
 
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_linfo_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_linfo_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_linfo_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_linfo_copy(const void *_mesg, void *_dest);
 static size_t H5O_linfo_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -111,8 +111,8 @@ H5FL_DEFINE_STATIC(H5O_linfo_t);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_linfo_decode(H5F_t *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_linfo_decode(H5F_t *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_linfo_t	*linfo = NULL;  /* Link info */
     unsigned char index_flags;  /* Flags for encoding link index info */
diff --git a/src/H5Olink.c b/src/H5Olink.c
index a4449f0..96d4747 100644
--- a/src/H5Olink.c
+++ b/src/H5Olink.c
@@ -38,8 +38,8 @@
 
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_link_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_link_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_link_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_link_copy(const void *_mesg, void *_dest);
 static size_t H5O_link_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -116,8 +116,8 @@ H5FL_DEFINE_STATIC(H5O_link_t);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_link_decode(H5F_t *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_link_decode(H5F_t *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_link_t          *lnk = NULL;    /* Pointer to link message */
     size_t              len = 0;        /* Length of a string in the message */
diff --git a/src/H5Omessage.c b/src/H5Omessage.c
index a63299a..286240c 100644
--- a/src/H5Omessage.c
+++ b/src/H5Omessage.c
@@ -1804,10 +1804,16 @@ done:
  *		slu@ncsa.uiuc.edu
  *		July 14, 2004
  *
+ * Modifications: Neil Fortner
+ *              Feb 4 2009
+ *              Added open_oh parameter.  This parameter is optional and
+ *              contains this message's protected object header
+ *
  *-------------------------------------------------------------------------
  */
 void *
-H5O_msg_decode(H5F_t *f, hid_t dxpl_id, unsigned type_id, const unsigned char *buf)
+H5O_msg_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned type_id,
+    const unsigned char *buf)
 {
     const H5O_msg_class_t   *type;      /* Actual H5O class type for the ID */
     void *ret_value;                    /* Return value */
@@ -1822,7 +1828,7 @@ H5O_msg_decode(H5F_t *f, hid_t dxpl_id, unsigned type_id, const unsigned char *b
     HDassert(type);
 
     /* decode */
-    if((ret_value = (type->decode)(f, dxpl_id, 0, &ioflags, buf)) == NULL)
+    if((ret_value = (type->decode)(f, dxpl_id, open_oh, 0, &ioflags, buf)) == NULL)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "unable to decode message")
 
 done:
diff --git a/src/H5Omtime.c b/src/H5Omtime.c
index 46272a0..1bbcfe3 100644
--- a/src/H5Omtime.c
+++ b/src/H5Omtime.c
@@ -28,13 +28,13 @@
 #include "H5Opkg.h"             /* Object headers			*/
 
 
-static void *H5O_mtime_new_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_mtime_new_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_mtime_new_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static size_t H5O_mtime_new_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
 
-static void *H5O_mtime_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_mtime_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_mtime_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_mtime_copy(const void *_mesg, void *_dest);
 static size_t H5O_mtime_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -119,8 +119,8 @@ H5FL_DEFINE(time_t);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_mtime_new_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_mtime_new_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     time_t	*mesg;
     uint32_t    tmp_time;       /* Temporary copy of the time */
@@ -172,8 +172,8 @@ done:
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_mtime_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_mtime_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     time_t	*mesg, the_time;
     int	i;
diff --git a/src/H5Oname.c b/src/H5Oname.c
index 915546b..5ffa870 100644
--- a/src/H5Oname.c
+++ b/src/H5Oname.c
@@ -33,8 +33,8 @@
 
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_name_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_name_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_name_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_name_copy(const void *_mesg, void *_dest);
 static size_t H5O_name_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -84,8 +84,8 @@ const H5O_msg_class_t H5O_MSG_NAME[1] = {{
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_name_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_name_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_name_t          *mesg;
     void                *ret_value;     /* Return value */
diff --git a/src/H5Opkg.h b/src/H5Opkg.h
index fa69b93..4bc6d26 100644
--- a/src/H5Opkg.h
+++ b/src/H5Opkg.h
@@ -187,7 +187,7 @@
                                                                               \
         /* Decode the message */                                              \
         HDassert(msg_type->decode);                                           \
-        if(NULL == ((MSG)->native = (msg_type->decode)((F), (DXPL), (MSG)->flags, &ioflags, (MSG)->raw))) \
+        if(NULL == ((MSG)->native = (msg_type->decode)((F), (DXPL), (OH), (MSG)->flags, &ioflags, (MSG)->raw))) \
             HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, ERR, "unable to decode message") \
                                                                               \
         /* Mark the message dirty if it was changed by decoding */            \
@@ -222,7 +222,7 @@ struct H5O_msg_class_t {
     const char	*name;				/*for debugging             */
     size_t	native_size;			/*size of native message    */
     unsigned    share_flags;			/* Message sharing settings */
-    void	*(*decode)(H5F_t*, hid_t, unsigned, unsigned *, const uint8_t *);
+    void	*(*decode)(H5F_t*, hid_t, H5O_t *, unsigned, unsigned *, const uint8_t *);
     herr_t	(*encode)(H5F_t*, hbool_t, uint8_t*, const void *);
     void	*(*copy)(const void *, void *);	/*copy native value         */
     size_t	(*raw_size)(const H5F_t *, hbool_t, const void *);/*sizeof encoded message	*/
@@ -515,8 +515,8 @@ H5_DLL herr_t H5O_release_mesg(H5F_t *f, hid_t dxpl_id, H5O_t *oh,
     H5O_mesg_t *mesg, hbool_t adj_link);
 
 /* Shared object operators */
-H5_DLL void * H5O_shared_decode(H5F_t *f, hid_t dxpl_id, unsigned *ioflags,
-    const uint8_t *buf, const H5O_msg_class_t *type);
+H5_DLL void * H5O_shared_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned *ioflags, const uint8_t *buf, const H5O_msg_class_t *type);
 H5_DLL herr_t H5O_shared_encode(const H5F_t *f, uint8_t *buf/*out*/, const H5O_shared_t *sh_mesg);
 H5_DLL size_t H5O_shared_size(const H5F_t *f, const H5O_shared_t *sh_mesg);
 H5_DLL herr_t H5O_shared_delete(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
diff --git a/src/H5Opline.c b/src/H5Opline.c
index fed2861..20a9d26 100644
--- a/src/H5Opline.c
+++ b/src/H5Opline.c
@@ -33,8 +33,8 @@
 
 /* PRIVATE PROTOTYPES */
 static herr_t H5O_pline_encode(H5F_t *f, uint8_t *p, const void *mesg);
-static void *H5O_pline_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_pline_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static void *H5O_pline_copy(const void *_mesg, void *_dest);
 static size_t H5O_pline_size(const H5F_t *f, const void *_mesg);
 static herr_t H5O_pline_reset(void *_mesg);
@@ -107,8 +107,8 @@ H5FL_DEFINE(H5O_pline_t);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_pline_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_pline_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_pline_t		*pline = NULL;          /* Pipeline message */
     H5Z_filter_info_t   *filter;                /* Filter to decode */
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index 524f786..00c832a 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -574,6 +574,7 @@ H5_DLL herr_t H5O_create(H5F_t *f, hid_t dxpl_id, size_t size_hint,
 H5_DLL herr_t H5O_open(H5O_loc_t *loc);
 H5_DLL herr_t H5O_close(H5O_loc_t *loc);
 H5_DLL int H5O_link(const H5O_loc_t *loc, int adjust, hid_t dxpl_id);
+H5_DLL int H5O_link_oh(H5F_t *f, int adjust, hid_t dxpl_id, H5O_t *oh, unsigned *oh_flags);
 H5_DLL H5O_t *H5O_protect(H5O_loc_t *loc, hid_t dxpl_id);
 H5_DLL herr_t H5O_unprotect(H5O_loc_t *loc, H5O_t *oh);
 H5_DLL herr_t H5O_touch(H5O_loc_t *loc, hbool_t force, hid_t dxpl_id);
@@ -634,8 +635,8 @@ H5_DLL herr_t H5O_msg_get_crt_index(unsigned type_id, const void *mesg,
     H5O_msg_crt_idx_t *crt_idx);
 H5_DLL herr_t H5O_msg_encode(H5F_t *f, unsigned type_id, hbool_t disable_shared,
     unsigned char *buf, const void *obj);
-H5_DLL void* H5O_msg_decode(H5F_t *f, hid_t dxpl_id, unsigned type_id,
-    const unsigned char *buf);
+H5_DLL void* H5O_msg_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned type_id, const unsigned char *buf);
 H5_DLL herr_t H5O_msg_delete(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
     unsigned type_id, void *mesg);
 
diff --git a/src/H5Orefcount.c b/src/H5Orefcount.c
index b2f02b2..2f00e86 100644
--- a/src/H5Orefcount.c
+++ b/src/H5Orefcount.c
@@ -33,8 +33,8 @@
 
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_refcount_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_refcount_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_refcount_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_refcount_copy(const void *_mesg, void *_dest);
 static size_t H5O_refcount_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -90,8 +90,8 @@ H5FL_DEFINE_STATIC(H5O_refcount_t);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_refcount_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_refcount_decode(H5F_t UNUSED *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_refcount_t *refcount = NULL;  /* Reference count */
     void        *ret_value;     /* Return value */
diff --git a/src/H5Osdspace.c b/src/H5Osdspace.c
index fe7bf02..23af101 100644
--- a/src/H5Osdspace.c
+++ b/src/H5Osdspace.c
@@ -26,8 +26,8 @@
 
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_sdspace_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_sdspace_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_sdspace_encode(H5F_t *f, uint8_t *p, const void *_mesg);
 static void *H5O_sdspace_copy(const void *_mesg, void *_dest);
 static size_t H5O_sdspace_size(const H5F_t *f, const void *_mesg);
@@ -109,8 +109,8 @@ H5FL_ARR_EXTERN(hsize_t);
     within this function using malloc() and is returned to the caller.
 --------------------------------------------------------------------------*/
 static void *
-H5O_sdspace_decode(H5F_t *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_sdspace_decode(H5F_t *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5S_extent_t	*sdim = NULL;/* New extent dimensionality structure */
     void		*ret_value;
diff --git a/src/H5Oshared.c b/src/H5Oshared.c
index 062443a..e22a105 100644
--- a/src/H5Oshared.c
+++ b/src/H5Oshared.c
@@ -107,7 +107,7 @@
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_shared_read(H5F_t *f, hid_t dxpl_id, unsigned *ioflags,
+H5O_shared_read(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned *ioflags,
     const H5O_shared_t *shared, const H5O_msg_class_t *type)
 {
     H5HF_t *fheap = NULL;
@@ -159,7 +159,7 @@ H5O_shared_read(H5F_t *f, hid_t dxpl_id, unsigned *ioflags,
             HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "can't read message from fractal heap.")
 
         /* Decode the message */
-        if(NULL == (ret_value = (type->decode)(f, dxpl_id, 0, ioflags, mesg_ptr)))
+        if(NULL == (ret_value = (type->decode)(f, dxpl_id, open_oh, 0, ioflags, mesg_ptr)))
             HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "can't decode shared message.")
     } /* end if */
     else {
@@ -167,12 +167,22 @@ H5O_shared_read(H5F_t *f, hid_t dxpl_id, unsigned *ioflags,
 
         HDassert(shared->type == H5O_SHARE_TYPE_COMMITTED);
 
-        /* Get the shared message from an object header */
+        /* Build the object location for the shared message's object header */
         oloc.file = f;
         oloc.addr = shared->u.loc.oh_addr;
         oloc.holding_file = FALSE;
-        if(NULL == (ret_value = H5O_msg_read(&oloc, type->id, NULL, dxpl_id)))
-            HGOTO_ERROR(H5E_OHDR, H5E_READERROR, NULL, "unable to read message")
+
+        if(open_oh && oloc.addr == H5O_OH_GET_ADDR(open_oh)) {
+            /* The shared message is in the already opened object header.  This
+             * is possible, for example, if an attribute's datatype is shared in
+             * the same object header the attribute is in.  Read the message
+             * directly. */
+            if(NULL == (ret_value = H5O_msg_read_oh(f, dxpl_id, open_oh, type->id, NULL)))
+                HGOTO_ERROR(H5E_OHDR, H5E_READERROR, NULL, "unable to read message")
+        } else
+            /* The shared message is in another object header */
+            if(NULL == (ret_value = H5O_msg_read(&oloc, type->id, NULL, dxpl_id)))
+                HGOTO_ERROR(H5E_OHDR, H5E_READERROR, NULL, "unable to read message")
     } /* end else */
 
     /* Mark the message as shared */
@@ -228,7 +238,7 @@ H5O_shared_link_adj(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
         H5O_loc_t oloc;         /* Location for object header where message is stored */
 
         /*
-         * The shared message is stored in some other object header.
+         * The shared message is stored in some object header.
          * The other object header must be in the same file as the
          * new object header. Adjust the reference count on that
          * object header.
@@ -236,13 +246,26 @@ H5O_shared_link_adj(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
         if(shared->file->shared != f->shared)
             HGOTO_ERROR(H5E_LINK, H5E_CANTINIT, FAIL, "interfile hard links are not allowed")
 
-        /* Get the shared message from an object header */
+        /* Build the object location for the shared message's object header */
         oloc.file = f;
         oloc.addr = shared->u.loc.oh_addr;
         oloc.holding_file = FALSE;
 
-        if(H5O_link(&oloc, adjust, dxpl_id) < 0)
-            HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "unable to adjust shared object link count")
+        if(open_oh && oloc.addr == H5O_OH_GET_ADDR(open_oh)) {
+            /* The shared message is in the already opened object header.  This
+             * is possible, for example, if an attribute's datatype is shared in
+             * the same object header the attribute is in.  Adjust the link
+             * count directly. */
+            unsigned oh_flags = H5AC__NO_FLAGS_SET; /* This is used only to satisfy H5O_link_oh */
+
+            if(H5O_link_oh(f, adjust, dxpl_id, open_oh, &oh_flags) < 0)
+                HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "unable to adjust shared object link count")
+
+            HDassert(!(oh_flags & H5AC__DELETED_FLAG));
+        } else
+            /* The shared message is in another object header */
+            if(H5O_link(&oloc, adjust, dxpl_id) < 0)
+                HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "unable to adjust shared object link count")
     } /* end if */
     else {
         HDassert(shared->type == H5O_SHARE_TYPE_SOHM || shared->type == H5O_SHARE_TYPE_HERE);
@@ -277,7 +300,7 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5O_shared_decode(H5F_t *f, hid_t dxpl_id, unsigned *ioflags,
+H5O_shared_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned *ioflags,
     const uint8_t *buf, const H5O_msg_class_t *type)
 {
     H5O_shared_t sh_mesg;       /* Shared message info */
@@ -344,7 +367,7 @@ H5O_shared_decode(H5F_t *f, hid_t dxpl_id, unsigned *ioflags,
     sh_mesg.msg_type_id = type->id;
 
     /* Retrieve actual message, through decoded shared message info */
-    if(NULL == (ret_value = H5O_shared_read(f, dxpl_id, ioflags, &sh_mesg, type)))
+    if(NULL == (ret_value = H5O_shared_read(f, dxpl_id, open_oh, ioflags, &sh_mesg, type)))
         HGOTO_ERROR(H5E_OHDR, H5E_READERROR, NULL, "unable to retrieve native message")
 
 done:
diff --git a/src/H5Oshared.h b/src/H5Oshared.h
index d52cd8f..c0f5cd6 100644
--- a/src/H5Oshared.h
+++ b/src/H5Oshared.h
@@ -48,7 +48,7 @@
  *-------------------------------------------------------------------------
  */
 static H5_inline void *
-H5O_SHARED_DECODE(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
+H5O_SHARED_DECODE(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned mesg_flags,
     unsigned *ioflags, const uint8_t *p)
 {
     void *ret_value;            /* Return value */
@@ -68,7 +68,7 @@ H5O_SHARED_DECODE(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
     /* Check for shared message */
     if(mesg_flags & H5O_MSG_FLAG_SHARED) {
         /* Retrieve native message info indirectly through shared message */
-        if(NULL == (ret_value = H5O_shared_decode(f, dxpl_id, ioflags, p, H5O_SHARED_TYPE)))
+        if(NULL == (ret_value = H5O_shared_decode(f, dxpl_id, open_oh, ioflags, p, H5O_SHARED_TYPE)))
 	    HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "unable to decode shared message")
 
         /* We currently do not support automatically fixing shared messages */
@@ -81,7 +81,7 @@ H5O_SHARED_DECODE(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
     } /* end if */
     else {
         /* Decode native message directly */
-        if(NULL == (ret_value = H5O_SHARED_DECODE_REAL(f, dxpl_id, mesg_flags, ioflags, p)))
+        if(NULL == (ret_value = H5O_SHARED_DECODE_REAL(f, dxpl_id, open_oh, mesg_flags, ioflags, p)))
 	    HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "unable to decode native message")
     } /* end else */
 
diff --git a/src/H5Oshmesg.c b/src/H5Oshmesg.c
index 74fe739..51c1c55 100644
--- a/src/H5Oshmesg.c
+++ b/src/H5Oshmesg.c
@@ -28,8 +28,8 @@
 #include "H5Opkg.h"             /* Object headers			*/
 #include "H5MMprivate.h"	/* Memory management			*/
 
-static void  *H5O_shmesg_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void  *H5O_shmesg_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_shmesg_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void  *H5O_shmesg_copy(const void *_mesg, void *_dest);
 static size_t H5O_shmesg_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -76,8 +76,8 @@ const H5O_msg_class_t H5O_MSG_SHMESG[1] = {{
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_shmesg_decode(H5F_t *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_shmesg_decode(H5F_t *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_shmesg_table_t	*mesg;          /* Native message */
     void                *ret_value;     /* Return value */
diff --git a/src/H5Ostab.c b/src/H5Ostab.c
index 9524f43..a93a46d 100644
--- a/src/H5Ostab.c
+++ b/src/H5Ostab.c
@@ -36,8 +36,8 @@
 
 
 /* PRIVATE PROTOTYPES */
-static void *H5O_stab_decode(H5F_t *f, hid_t dxpl_id, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p);
+static void *H5O_stab_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
+    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
 static herr_t H5O_stab_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_stab_copy(const void *_mesg, void *_dest);
 static size_t H5O_stab_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -96,8 +96,8 @@ H5FL_DEFINE_STATIC(H5O_stab_t);
  *-------------------------------------------------------------------------
  */
 static void *
-H5O_stab_decode(H5F_t *f, hid_t UNUSED dxpl_id, unsigned UNUSED mesg_flags,
-    unsigned UNUSED *ioflags, const uint8_t *p)
+H5O_stab_decode(H5F_t *f, hid_t UNUSED dxpl_id, H5O_t UNUSED *open_oh,
+    unsigned UNUSED mesg_flags, unsigned UNUSED *ioflags, const uint8_t *p)
 {
     H5O_stab_t          *stab = NULL;
     void                *ret_value;     /* Return value */
diff --git a/src/H5S.c b/src/H5S.c
index b7982f0..40134a6 100644
--- a/src/H5S.c
+++ b/src/H5S.c
@@ -1565,7 +1565,7 @@ H5S_decode(const unsigned char *buf)
 
     /* Decode the extent part of dataspace */
     /* (pass mostly bogus file pointer and bogus DXPL) */
-    if((extent = (H5S_extent_t *)H5O_msg_decode(f, H5P_DEFAULT, H5O_SDSPACE_ID, buf))==NULL)
+    if((extent = (H5S_extent_t *)H5O_msg_decode(f, H5P_DEFAULT, NULL, H5O_SDSPACE_ID, buf))==NULL)
 	HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDECODE, NULL, "can't decode object")
     buf += extent_size;
 
diff --git a/src/H5SM.c b/src/H5SM.c
index d942399..c383877 100755
--- a/src/H5SM.c
+++ b/src/H5SM.c
@@ -1402,7 +1402,7 @@ H5SM_delete(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, H5O_shared_t *sh_mesg)
      * master table needs to be unprotected when we do this.
      */
     if(mesg_buf) {
-        if(NULL == (native_mesg = H5O_msg_decode(f, dxpl_id, type_id, (const unsigned char *)mesg_buf)))
+        if(NULL == (native_mesg = H5O_msg_decode(f, dxpl_id, open_oh, type_id, (const unsigned char *)mesg_buf)))
             HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, FAIL, "can't decode shared message.")
 
         if(H5O_msg_delete(f, dxpl_id, open_oh, type_id, native_mesg) < 0)
diff --git a/src/H5T.c b/src/H5T.c
index d6bc1ed..7e978e7 100644
--- a/src/H5T.c
+++ b/src/H5T.c
@@ -2920,7 +2920,7 @@ H5T_decode(const unsigned char *buf)
 	HGOTO_ERROR(H5E_DATATYPE, H5E_VERSION, NULL, "unknown version of encoded datatype")
 
     /* Decode the serialized datatype message */
-    if((ret_value = H5O_msg_decode(f, H5AC_dxpl_id, H5O_DTYPE_ID, buf)) == NULL)
+    if((ret_value = H5O_msg_decode(f, H5AC_dxpl_id, NULL, H5O_DTYPE_ID, buf)) == NULL)
 	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTDECODE, NULL, "can't decode object")
 
 done:
diff --git a/test/tattr.c b/test/tattr.c
index fe092e6..b25d3a5 100644
--- a/test/tattr.c
+++ b/test/tattr.c
@@ -9773,6 +9773,135 @@ test_attr_bug2(hid_t fcpl, hid_t fapl)
 
 /****************************************************************
 **
+**  test_attr_bug3(): Test basic H5A (attribute) code.
+**      Tests creating and deleting attributes which use a
+**      datatype and/or dataspace stored in the same object
+**      header.
+**
+****************************************************************/
+static void
+test_attr_bug3(hid_t fcpl, hid_t fapl)
+{
+    hid_t   fid;            /* File ID */
+    hid_t   aid1, aid2;     /* Attribute IDs */
+    hid_t   sid1, sid2;     /* Dataspace ID */
+    hid_t   tid1, tid2;     /* Datatype IDs */
+    hid_t   did;            /* Dataset ID */
+    hsize_t dims1[2] = {2, 2},
+            dims2[2] = {3, 3}; /* Dimensions */
+    int     wdata1[2][2];
+    unsigned wdata2[3][3];  /* Write buffers */
+    herr_t  ret;            /* Generic return status */
+
+    /* Output message about test being performed */
+    MESSAGE(5, ("Testing Attributes in the Same Header as their Datatypes\n"));
+
+    /* Create dataspaces */
+    sid1 = H5Screate_simple(2, dims1, NULL);
+    CHECK(sid1, FAIL, "H5Screate_simple");
+    sid2 = H5Screate_simple(2, dims2, NULL);
+    CHECK(sid2, FAIL, "H5Screate_simple");
+
+    /* Create file to operate on */
+    fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl, fapl);
+    CHECK(fid, FAIL, "H5Fcreate");
+
+    /* Create datatypes and commit tid1 */
+    tid1 = H5Tcopy(H5T_STD_I16BE);
+    CHECK(tid1, FAIL, "H5Tcopy");
+    tid2 = H5Tcopy(H5T_STD_U64LE);
+    CHECK(tid1, FAIL, "H5Tcopy");
+    ret = H5Tcommit2(fid, "dtype", tid1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    CHECK(ret, FAIL, "H5Tcommit2");
+
+    /* Create dataset */
+    did = H5Dcreate2(fid, "dset", tid2, sid2, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    CHECK(did, FAIL, "H5Dcreate2");
+
+    /* Create attribute on datatype, using that datatype as its datatype */
+    aid1 = H5Acreate2(tid1, "attr", tid1, sid1, H5P_DEFAULT, H5P_DEFAULT);
+    CHECK(aid1, FAIL, "H5Acreate2");
+
+    /* Create attribute on dataset, using its datatype and dataspace */
+    aid2 = H5Acreate2(did, "attr", tid2, sid2, H5P_DEFAULT, H5P_DEFAULT);
+    CHECK(aid2, FAIL, "H5Acreate2");
+
+    /* Close attributes */
+    ret = H5Aclose(aid1);
+    CHECK(ret, FAIL, "H5Aclose");
+    ret = H5Aclose(aid2);
+    CHECK(ret, FAIL, "H5Aclose");
+
+    /* Reopen attributes */
+    aid1 = H5Aopen(tid1, "attr", H5P_DEFAULT);
+    CHECK(aid1, FAIL, "H5Aopen");
+    aid2 = H5Aopen(did, "attr", H5P_DEFAULT);
+    CHECK(aid2, FAIL, "H5Aopen");
+
+    /* Write data to the attributes (the data is uninitialized, we only care
+     * that H5Awrite succeeds for now) */
+    ret = H5Awrite(aid1, H5T_NATIVE_INT, wdata1[0]);
+    CHECK(ret, FAIL, "H5Awrite");
+    ret = H5Awrite(aid2, H5T_NATIVE_UINT, wdata2[0]);
+    CHECK(ret, FAIL, "H5Awrite");
+
+    /* Close attributes */
+    ret = H5Aclose(aid1);
+    CHECK(ret, FAIL, "H5Aclose");
+    ret = H5Aclose(aid2);
+    CHECK(ret, FAIL, "H5Aclose");
+
+    /* Delete attributes */
+    ret = H5Adelete(tid1, "attr");
+    CHECK(ret, FAIL, "H5Adelete");
+    ret = H5Adelete(did, "attr");
+    CHECK(ret, FAIL, "H5Adelete");
+
+    /* Recreate attributes */
+    aid1 = H5Acreate2(tid1, "attr", tid1, sid1, H5P_DEFAULT, H5P_DEFAULT);
+    CHECK(aid1, FAIL, "H5Acreate2");
+    aid2 = H5Acreate2(did, "attr", tid2, sid2, H5P_DEFAULT, H5P_DEFAULT);
+    CHECK(aid2, FAIL, "H5Acreate2");
+
+    /* Delete attributes (note they are still open) */
+    ret = H5Adelete(tid1, "attr");
+    CHECK(ret, FAIL, "H5Adelete");
+    ret = H5Adelete(did, "attr");
+    CHECK(ret, FAIL, "H5Adelete");
+
+    /* Close dataspaces and transient datatype */
+    ret = H5Sclose(sid1);
+    CHECK(ret, FAIL, "H5Sclose");
+    ret = H5Sclose(sid2);
+    CHECK(ret, FAIL, "H5Sclose");
+    ret = H5Tclose(tid2);
+    CHECK(ret, FAIL, "H5Tclose");
+
+    /* Close dataset and committed datatype */
+    ret = H5Tclose(tid1);
+    CHECK(ret, FAIL, "H5Tclose");
+    ret = H5Dclose(did);
+    CHECK(ret, FAIL, "H5Dclose");
+
+    /* Delete dataset and committed datatype */
+    ret = H5Ldelete(fid, "dtype", H5P_DEFAULT);
+    CHECK(ret, FAIL, "H5Tclose");
+    ret = H5Ldelete(fid, "dset", H5P_DEFAULT);
+    CHECK(ret, FAIL, "H5Dclose");
+
+    /* Close attributes */
+    ret = H5Aclose(aid1);
+    CHECK(ret, FAIL, "H5Aclose");
+    ret = H5Aclose(aid2);
+    CHECK(ret, FAIL, "H5Aclose");
+
+    /* Close file */
+    ret = H5Fclose(fid);
+    CHECK(ret, FAIL, "H5Fclose");
+}   /* test_attr_bug3() */
+
+/****************************************************************
+**
 **  test_attr(): Main H5A (attribute) testing routine.
 **
 ****************************************************************/
@@ -9913,6 +10042,7 @@ test_attr(void)
                 /* Tests that address specific bugs */
                 test_attr_bug1(my_fcpl, my_fapl);               /* Test odd allocation operations */
                 test_attr_bug2(my_fcpl, my_fapl);               /* Test many deleted attributes */
+                test_attr_bug3(my_fcpl, my_fapl);               /* Test "self referential" attributes */
             } /* end for */
         } /* end if */
         else {
@@ -9933,6 +10063,7 @@ test_attr(void)
             /* Tests that address specific bugs */
             test_attr_bug1(fcpl, my_fapl);                      /* Test odd allocation operations */
             test_attr_bug2(fcpl, my_fapl);                      /* Test many deleted attributes */
+            test_attr_bug3(fcpl, my_fapl);                      /* Test "self referential" attributes */
         } /* end else */
     } /* end for */