[svn-r12872] Description:

    Implement basic framework for H5Lget_info_by_idx and get it working for
creation order indices on compact groups.

    Clean up code a bit.
    
    Close resource link in user-defined link traversal.

Tested on:
    Linux/32 2.6 (chicago)

10 files changed, 609 insertions, 148 deletions

diff --git a/src/H5Glink.c b/src/H5Glink.c
index 6611ea0..73b974e 100644
--- a/src/H5Glink.c
+++ b/src/H5Glink.c
@@ -88,7 +88,8 @@ typedef struct {
 /* PRIVATE PROTOTYPES */
 static herr_t H5G_link_build_table_cb(const void *_mesg, unsigned idx, void *_udata);
 static herr_t H5G_link_build_table(H5O_loc_t *oloc, hid_t dxpl_id,
-    const H5O_linfo_t *linfo, H5_iter_order_t order, H5G_link_table_t *ltable);
+    const H5O_linfo_t *linfo, H5L_index_t idx_type, H5_iter_order_t order,
+    H5G_link_table_t *ltable);
 
 
 /*-------------------------------------------------------------------------
@@ -120,7 +121,7 @@ H5G_link_build_table_cb(const void *_mesg, unsigned UNUSED idx, void *_udata)
     HDassert(udata->curr_lnk < udata->ltable->nlinks);
 
     /* Copy link message into table */
-    if(H5O_copy(H5O_LINK_ID, lnk, &(udata->ltable->lnks[udata->curr_lnk])) == NULL)
+    if(NULL == H5O_copy(H5O_LINK_ID, lnk, &(udata->ltable->lnks[udata->curr_lnk])))
         HGOTO_ERROR(H5E_SYM, H5E_CANTCOPY, H5O_ITER_ERROR, "can't copy link message")
 
     /* Increment current link entry to operate on */
@@ -147,7 +148,7 @@ done:
  */
 static herr_t
 H5G_link_build_table(H5O_loc_t *oloc, hid_t dxpl_id, const H5O_linfo_t *linfo,
-    H5_iter_order_t order, H5G_link_table_t *ltable)
+    H5L_index_t idx_type, H5_iter_order_t order, H5G_link_table_t *ltable)
 {
     herr_t	ret_value = SUCCEED;    /* Return value */
 
@@ -178,13 +179,22 @@ H5G_link_build_table(H5O_loc_t *oloc, hid_t dxpl_id, const H5O_linfo_t *linfo,
             HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "error iterating over link messages")
 
         /* Sort link table in correct iteration order */
-        /* (XXX: by name, currently) */
-        if(order == H5_ITER_INC)
-            HDqsort(ltable->lnks, ltable->nlinks, sizeof(H5O_link_t), H5G_obj_cmp_name_inc);
-        else if(order == H5_ITER_INC)
-            HDqsort(ltable->lnks, ltable->nlinks, sizeof(H5O_link_t), H5G_obj_cmp_name_dec);
-        else
-            HDassert(order == H5_ITER_NATIVE);
+        if(idx_type == H5L_INDEX_NAME) {
+            if(order == H5_ITER_INC)
+                HDqsort(ltable->lnks, ltable->nlinks, sizeof(H5O_link_t), H5G_obj_cmp_name_inc);
+            else if(order == H5_ITER_INC)
+                HDqsort(ltable->lnks, ltable->nlinks, sizeof(H5O_link_t), H5G_obj_cmp_name_dec);
+            else
+                HDassert(order == H5_ITER_NATIVE);
+        } /* end if */
+        else {
+            if(order == H5_ITER_INC)
+                HDqsort(ltable->lnks, ltable->nlinks, sizeof(H5O_link_t), H5G_obj_cmp_corder_inc);
+            else if(order == H5_ITER_INC)
+                HDqsort(ltable->lnks, ltable->nlinks, sizeof(H5O_link_t), H5G_obj_cmp_corder_dec);
+            else
+                HDassert(order == H5_ITER_NATIVE);
+        } /* end else */
     } /* end if */
     else
         ltable->lnks = NULL;
@@ -439,7 +449,7 @@ H5G_link_get_name_by_idx(H5O_loc_t *oloc, hid_t dxpl_id,
     HDassert(oloc);
 
     /* Build table of all link messages */
-    if(H5G_link_build_table(oloc, dxpl_id, linfo, H5_ITER_INC, &ltable) < 0)
+    if(H5G_link_build_table(oloc, dxpl_id, linfo, H5L_INDEX_NAME, H5_ITER_INC, &ltable) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "can't create link message table")
 
     /* Check for going out of bounds */
@@ -494,12 +504,12 @@ H5G_link_get_type_by_idx(H5O_loc_t *oloc, hid_t dxpl_id, const H5O_linfo_t *linf
     HDassert(oloc);
 
     /* Build table of all link messages */
-    if(H5G_link_build_table(oloc, dxpl_id, linfo, H5_ITER_INC, &ltable) < 0)
+    if(H5G_link_build_table(oloc, dxpl_id, linfo, H5L_INDEX_NAME, H5_ITER_INC, &ltable) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, H5G_UNKNOWN, "can't create link message table")
 
     /* Check for going out of bounds */
     if(idx >= ltable.nlinks)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5G_UNKNOWN, "index out of bound")
+	HGOTO_ERROR(H5E_ARGS, H5E_BADRANGE, H5G_UNKNOWN, "index out of bound")
 
     /* Determine type of object */
     if(ltable.lnks[idx].type == H5L_TYPE_SOFT)
@@ -664,7 +674,7 @@ H5G_link_iterate(H5O_loc_t *oloc, hid_t dxpl_id, const H5O_linfo_t *linfo,
     HDassert(op.lib_op);
 
     /* Build table of all link messages */
-    if(H5G_link_build_table(oloc, dxpl_id, linfo, order, &ltable) < 0)
+    if(H5G_link_build_table(oloc, dxpl_id, linfo, H5L_INDEX_NAME, order, &ltable) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "can't create link message table")
 
     /* Iterate over link messages */
@@ -731,7 +741,7 @@ H5G_link_lookup_cb(const void *_mesg, unsigned UNUSED idx, void *_udata)
     if(HDstrcmp(lnk->name, udata->name) == 0) {
         if(udata->lnk) {
             /* Copy link information */
-            if(H5O_copy(H5O_LINK_ID, lnk, udata->lnk) == NULL)
+            if(NULL == H5O_copy(H5O_LINK_ID, lnk, udata->lnk))
                 HGOTO_ERROR(H5E_SYM, H5E_CANTCOPY, H5O_ITER_ERROR, "can't copy link message")
         } /* end if */
 
@@ -790,3 +800,59 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_link_lookup() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:	H5G_link_lookup_by_corder
+ *
+ * Purpose:	Look up an object in a group using link messages, according
+ *              the link's creation order.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@hdfgroup.org
+ *		Nov  6 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5G_link_lookup_by_corder(H5O_loc_t *oloc, hid_t dxpl_id, const H5O_linfo_t *linfo,
+    H5_iter_order_t order, hsize_t n, H5O_link_t *lnk)
+{
+    H5G_link_table_t    ltable = {0, NULL};     /* Link table */
+    herr_t     ret_value = SUCCEED;     /* Return value */
+
+    FUNC_ENTER_NOAPI(H5G_link_lookup_by_corder, FAIL)
+
+    /* check arguments */
+    HDassert(oloc && oloc->file);
+    HDassert(linfo);
+    HDassert(lnk);
+
+    /* Build table of all link messages, sorted according to desired order */
+    if(H5G_link_build_table(oloc, dxpl_id, linfo, H5L_INDEX_CORDER, order, &ltable) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "can't create link message table")
+
+    /* Check for going out of bounds */
+    if(n >= ltable.nlinks)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADRANGE, FAIL, "index out of bound")
+
+    /* Copy link information */
+#ifdef QAK
+HDfprintf(stderr, "%s: ltable.lnks[%Hu].corder = %Hd\n", FUNC, n, ltable.lnks[n].corder);
+HDfprintf(stderr, "%s: ltable.lnks[%Hu].corder_valid = %t\n", FUNC, n, ltable.lnks[n].corder_valid);
+#endif /* QAK */
+    if(NULL == H5O_copy(H5O_LINK_ID, &ltable.lnks[n], lnk))
+        HGOTO_ERROR(H5E_SYM, H5E_CANTCOPY, H5O_ITER_ERROR, "can't copy link message")
+
+done:
+    /* Release link table */
+    if(ltable.lnks) {
+        /* Free link table information */
+        if(H5G_obj_release_table(&ltable) < 0)
+            HDONE_ERROR(H5E_SYM, H5E_CANTFREE, FAIL, "unable to release link table")
+    } /* end if */
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5G_link_lookup_by_corder() */
+
diff --git a/src/H5Gobj.c b/src/H5Gobj.c
index 0762b87..633ac5c 100644
--- a/src/H5Gobj.c
+++ b/src/H5Gobj.c
@@ -163,6 +163,76 @@ H5G_obj_cmp_name_dec(const void *lnk1, const void *lnk2)
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5G_obj_cmp_corder_inc
+ *
+ * Purpose:	Callback routine for comparing two link creation orders, in
+ *              increasing order
+ *
+ * Return:	An integer less than, equal to, or greater than zero if the
+ *              first argument is considered to be respectively less than,
+ *              equal to, or greater than the second.  If two members compare
+ *              as equal, their order in the sorted array is undefined.
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@hdfgroup.org
+ *		Nov  6 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+int
+H5G_obj_cmp_corder_inc(const void *lnk1, const void *lnk2)
+{
+    int ret_value;              /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5G_obj_cmp_corder_inc)
+
+    if(((const H5O_link_t *)lnk1)->corder < ((const H5O_link_t *)lnk2)->corder)
+        ret_value = -1;
+    else if(((const H5O_link_t *)lnk1)->corder > ((const H5O_link_t *)lnk2)->corder)
+        ret_value = 1;
+    else
+        ret_value = 0;
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5G_obj_cmp_corder_inc() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5G_obj_cmp_corder_dec
+ *
+ * Purpose:	Callback routine for comparing two link creation orders, in
+ *              decreasing order
+ *
+ * Return:	An integer less than, equal to, or greater than zero if the
+ *              second argument is considered to be respectively less than,
+ *              equal to, or greater than the first.  If two members compare
+ *              as equal, their order in the sorted array is undefined.
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@hdfgroup.org
+ *		Nov  6 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+int
+H5G_obj_cmp_corder_dec(const void *lnk1, const void *lnk2)
+{
+    int ret_value;              /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5G_obj_cmp_corder_dec)
+
+    if(((const H5O_link_t *)lnk1)->corder < ((const H5O_link_t *)lnk2)->corder)
+        ret_value = 1;
+    else if(((const H5O_link_t *)lnk1)->corder > ((const H5O_link_t *)lnk2)->corder)
+        ret_value = -1;
+    else
+        ret_value = 0;
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5G_obj_cmp_corder_dec() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5G_obj_release_table
  *
  * Purpose:     Release table containing a list of links for a group
@@ -1022,7 +1092,7 @@ done:
 /*-------------------------------------------------------------------------
  * Function:	H5G_obj_lookup
  *
- * Purpose:	Look up a link in a group.
+ * Purpose:	Look up a link in a group, using the name as the key.
  *
  * Return:	Non-negative on success/Negative on failure
  *
@@ -1072,3 +1142,90 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_obj_lookup() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:	H5G_obj_lookup_by_idx
+ *
+ * Purpose:	Look up a link in a group, according to an order within an
+ *              index.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@hdfgroup.org
+ *		Nov  6 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5G_obj_lookup_by_idx(H5O_loc_t *grp_oloc, H5L_index_t idx_type,
+    H5_iter_order_t order, hsize_t n, H5O_link_t *lnk, hid_t dxpl_id)
+{
+    H5O_linfo_t linfo;		        /* Link info message */
+    herr_t     ret_value = SUCCEED;     /* Return value */
+
+    FUNC_ENTER_NOAPI(H5G_obj_lookup_by_idx, FAIL)
+
+    /* check arguments */
+    HDassert(grp_oloc && grp_oloc->file);
+
+    /* Attempt to get the link info message for this group */
+    if(H5O_read(grp_oloc, H5O_LINFO_ID, 0, &linfo, dxpl_id)) {
+        /* Check for query on the name */
+        if(idx_type == H5L_INDEX_NAME) {
+            /* Check for dense link storage */
+            if(H5F_addr_defined(linfo.link_fheap_addr)) {
+                /* Get the object's info from the dense link storage */
+                if(H5G_dense_lookup(grp_oloc->file, dxpl_id, &linfo, "", lnk) < 0)
+                    HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "can't locate object")
+            } /* end if */
+            else {
+                /* Get the object's info from the link messages */
+                if(H5G_link_lookup(grp_oloc, "", lnk, dxpl_id) < 0)
+                    HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "can't locate object")
+            } /* end else */
+        } /* end if */
+        else {
+            H5O_ginfo_t ginfo;		        /* Group info message */
+
+            /* Get group info message, to see if creation order is stored for links in this group */
+            if(NULL == H5O_read(grp_oloc, H5O_GINFO_ID, 0, &ginfo, dxpl_id))
+                HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "can't retrieve group info message for group")
+
+            /* Check if creation order is tracked */
+            if(!ginfo.track_corder)
+                HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "creation order not tracked for links in group")
+
+            /* Check for dense link storage */
+            if(H5F_addr_defined(linfo.link_fheap_addr)) {
+HDfprintf(stderr, "%s: creation order query on dense storage not implemented yet!\n", FUNC);
+HGOTO_ERROR(H5E_SYM, H5E_UNSUPPORTED, FAIL, "creation order query on dense storage not implemented yet")
+            } /* end if */
+            else {
+                /* Get the object's info from the link messages */
+                if(H5G_link_lookup_by_corder(grp_oloc, dxpl_id, &linfo, order, n, lnk) < 0)
+                    HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "can't locate object")
+            } /* end else */
+        } /* end else */
+    } /* end if */
+    else {
+        /* Clear error stack from not finding the link info message */
+        H5E_clear_stack(NULL);
+
+        /* Can only perform name lookups on groups with symbol tables */
+        if(idx_type != H5L_INDEX_NAME)
+            HGOTO_ERROR(H5E_SYM, H5E_BADVALUE, FAIL, "no creation order index to query")
+if(order == H5_ITER_DEC) {
+    HDfprintf(stderr, "%s: decreasing order query on symbol table not implemented yet!\n", FUNC);
+    HGOTO_ERROR(H5E_SYM, H5E_UNSUPPORTED, FAIL, "decreasing order query on symbol table not implemented yet")
+} /* end if */
+
+        /* Get the object's info from the symbol table */
+        if(H5G_stab_lookup(grp_oloc, "", lnk, dxpl_id) < 0)
+            HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "can't locate object")
+    } /* end else */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5G_obj_lookup_by_idx() */
+
diff --git a/src/H5Gpkg.h b/src/H5Gpkg.h
index db4d8c1..9c1928b 100644
--- a/src/H5Gpkg.h
+++ b/src/H5Gpkg.h
@@ -429,6 +429,9 @@ H5_DLL herr_t H5G_link_iterate(H5O_loc_t *oloc, hid_t dxpl_id, const H5O_linfo_t
     int *last_obj, H5G_link_iterate_t op, void *op_data);
 H5_DLL herr_t H5G_link_lookup(H5O_loc_t *grp_oloc, const char *name,
     H5O_link_t *lnk, hid_t dxpl_id);
+H5_DLL herr_t H5G_link_lookup_by_corder(H5O_loc_t *oloc, hid_t dxpl_id,
+    const H5O_linfo_t *linfo, H5_iter_order_t order, hsize_t n,
+    H5O_link_t *lnk);
 
 /* Functions that understand "dense" link storage */
 H5_DLL herr_t H5G_dense_build_table(H5F_t *f, hid_t dxpl_id, const H5O_linfo_t *linfo,
@@ -453,26 +456,28 @@ H5_DLL herr_t H5G_dense_delete(H5F_t *f, hid_t dxpl_id, H5O_linfo_t *linfo,
 /* Functions that understand objects */
 H5_DLL int H5G_obj_cmp_name_inc(const void *lnk1, const void *lnk2);
 H5_DLL int H5G_obj_cmp_name_dec(const void *lnk1, const void *lnk2);
+H5_DLL int H5G_obj_cmp_corder_inc(const void *lnk1, const void *lnk2);
+H5_DLL int H5G_obj_cmp_corder_dec(const void *lnk1, const void *lnk2);
 H5_DLL herr_t H5G_obj_release_table(H5G_link_table_t *ltable);
 H5_DLL herr_t H5G_obj_create(H5F_t *f, hid_t dxpl_id, const H5O_ginfo_t *ginfo,
     const H5O_linfo_t *linfo, H5O_loc_t *oloc/*out*/);
 H5_DLL herr_t H5G_obj_insert(H5O_loc_t *grp_oloc, const char *name,
     H5O_link_t *obj_lnk, hbool_t adj_link, hid_t dxpl_id);
-H5_DLL herr_t H5G_obj_lookup(H5O_loc_t *grp_oloc, const char *name,
-    H5O_link_t *lnk, hid_t dxpl_id);
 H5_DLL herr_t H5G_obj_iterate(hid_t loc_id, const char *name,
     H5_iter_order_t order, int skip, int *last_obj, H5G_iterate_t op,
     void *op_data, hid_t dxpl_id);
-H5_DLL herr_t H5G_obj_count(struct H5O_loc_t *oloc, hsize_t *num_objs, hid_t dxpl_id);
+H5_DLL herr_t H5G_obj_count(struct H5O_loc_t *oloc, hsize_t *num_objs,
+    hid_t dxpl_id);
 H5_DLL ssize_t H5G_obj_get_name_by_idx(H5O_loc_t *oloc, hsize_t idx,
     char* name, size_t size, hid_t dxpl_id);
 H5_DLL H5G_obj_t H5G_obj_get_type_by_idx(H5O_loc_t *oloc, hsize_t idx,
     hid_t dxpl_id);
 H5_DLL herr_t H5G_obj_remove(H5O_loc_t *oloc, const char *name,
     H5G_obj_t *obj_type, hid_t dxpl_id);
-H5_DLL herr_t H5G_obj_find(H5G_loc_t *loc, const char *name,
-    unsigned traverse_flags, H5O_link_t *lnk, H5O_loc_t *obj_oloc,
-    hid_t lapl_id, hid_t dxpl_id);
+H5_DLL herr_t H5G_obj_lookup(H5O_loc_t *grp_oloc, const char *name,
+    H5O_link_t *lnk, hid_t dxpl_id);
+H5_DLL herr_t H5G_obj_lookup_by_idx(H5O_loc_t *grp_oloc, H5L_index_t idx_type,
+    H5_iter_order_t order, hsize_t n, H5O_link_t *lnk, hid_t dxpl_id);
 
 /*
  * These functions operate on group hierarchy names.
diff --git a/src/H5Gprivate.h b/src/H5Gprivate.h
index 6ca2b68..23cc895 100644
--- a/src/H5Gprivate.h
+++ b/src/H5Gprivate.h
@@ -193,5 +193,5 @@ H5_DLL herr_t H5G_loc_find(H5G_loc_t *loc, const char *name,
 H5_DLL herr_t H5G_loc_reset(H5G_loc_t *loc);
 H5_DLL herr_t H5G_loc_free(H5G_loc_t *loc);
 
-#endif
+#endif /* _H5Gprivate_H */
 
diff --git a/src/H5Gpublic.h b/src/H5Gpublic.h
index 4f0117a..8048aee 100644
--- a/src/H5Gpublic.h
+++ b/src/H5Gpublic.h
@@ -92,17 +92,6 @@ typedef struct H5G_stat_t {
 /* Prototype for H5Giterate() operator */
 typedef herr_t (*H5G_iterate_t)(hid_t group, const char *name, void *op_data);
 
-/*
- * The types of indices on links in groups.  Primarily used for "<do> <foo> by
- * index" routines and for iterating over links in groups.
- */
-typedef enum H5G_index_t {
-    H5G_INDEX_UNKNOWN = -1,	/* Unknown index type			*/
-    H5G_INDEX_NAME,		/* Index on names of links		*/
-    H5G_INDEX_CORDER,		/* Index on creation order of links	*/
-    H5G_INDEX_N			/* Number of indices defined on links in groups */
-} H5G_index_t;
-
 /********************/
 /* Public Variables */
 /********************/
diff --git a/src/H5Gtraverse.c b/src/H5Gtraverse.c
index c1f8440..4c92bc4 100644
--- a/src/H5Gtraverse.c
+++ b/src/H5Gtraverse.c
@@ -146,8 +146,9 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-static herr_t H5G_traverse_ud(H5G_loc_t *grp_loc/*in,out*/, H5O_link_t *lnk,
-    H5G_loc_t *obj_loc/*in,out*/, size_t *nlinks/*in,out*/, hid_t lapl_id,
+static herr_t
+H5G_traverse_ud(H5G_loc_t *grp_loc/*in,out*/, H5O_link_t *lnk,
+    H5G_loc_t *obj_loc/*in,out*/, size_t *nlinks/*in,out*/, hid_t _lapl_id,
     hid_t dxpl_id)
 {
     const H5L_class_t   *link_class;       /* User-defined link class */
@@ -158,7 +159,7 @@ static herr_t H5G_traverse_ud(H5G_loc_t *grp_loc/*in,out*/, H5O_link_t *lnk,
     H5O_loc_t          *new_oloc=NULL;
     H5F_t              *temp_file=NULL;
     H5G_t              *grp;
-    H5P_genplist_t     *lapl_default;
+    hid_t               lapl_id = (-1);         /* LAPL local to this routine */
     H5P_genplist_t     *lapl;                   /* LAPL with nlinks set */
     hid_t               cur_grp = (-1);
     herr_t              ret_value = SUCCEED;    /* Return value */
@@ -171,6 +172,7 @@ static herr_t H5G_traverse_ud(H5G_loc_t *grp_loc/*in,out*/, H5O_link_t *lnk,
     HDassert(lnk->type >= H5L_TYPE_UD_MIN);
     HDassert(obj_loc);
     HDassert(nlinks);
+    HDassert(_lapl_id >= 0);
 
     /* Reset the object's path information, because we can't detect any changes
      * in the "path" the user-defined callback takes */
@@ -196,17 +198,22 @@ static herr_t H5G_traverse_ud(H5G_loc_t *grp_loc/*in,out*/, H5O_link_t *lnk,
 
     /* Record number of soft links left to traverse in the property list.
      * If no property list exists yet, create one. */
-    if(lapl_id == H5P_DEFAULT) {
+    if(_lapl_id == H5P_DEFAULT || _lapl_id == H5P_LINK_ACCESS_DEFAULT) {
         HDassert(H5P_LINK_ACCESS_DEFAULT != -1);
-        if(NULL == (lapl_default = H5I_object(H5P_LINK_ACCESS_DEFAULT)))
+        if(NULL == (lapl = H5I_object(H5P_LINK_ACCESS_DEFAULT)))
             HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "unable to get default property list")
 
-        if((lapl_id = H5P_copy_plist(lapl_default)) < 0)
+        if((lapl_id = H5P_copy_plist(lapl)) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "unable to copy property list")
     } /* end if */
+    else {
+        /* Use the property list passed in */
+        lapl_id = _lapl_id;
+
+        if(NULL == (lapl = H5I_object(lapl_id)))
+            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "unable to get property list from ID")
+    } /* end else */
 
-    if(NULL == (lapl = H5I_object(lapl_id)))
-        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "unable to get property list from ID")
     if(H5P_set(lapl, H5L_ACS_NLINKS_NAME, nlinks) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set nlink info")
 
@@ -268,6 +275,11 @@ done:
         if(H5I_dec_ref(cb_return) < 0)
               HDONE_ERROR(H5E_ATOM, H5E_CANTRELEASE, FAIL, "unable to close atom from UD callback")
 
+    /* Close the LAPL, if we copied the default one */
+    if(lapl_id > 0 && lapl_id != _lapl_id)
+        if(H5I_dec_ref(lapl_id) < 0)
+              HDONE_ERROR(H5E_ATOM, H5E_CANTRELEASE, FAIL, "unable to close copied link access property list")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_traverse_ud() */
 
diff --git a/src/H5L.c b/src/H5L.c
index f3dcd5b..793d570 100644
--- a/src/H5L.c
+++ b/src/H5L.c
@@ -48,54 +48,67 @@
 /* Local Typedefs */
 /******************/
 
-/* User data for path traversal routine for getting link metadata */
+/* User data for path traversal routine for getting link info by name */
 typedef struct {
-    H5L_info_t      *linfo;                  /* Buffer to return to user */
-    hid_t           dxpl_id;                 /* dxpl to use in callback */
+    H5L_info_t      *linfo;             /* Buffer to return to user */
+    hid_t           dxpl_id;            /* dxpl to use in callback */
 } H5L_trav_ud1_t;
 
 /* User data for path traversal callback to creating a link */
 typedef struct {
-    H5F_t *file;                              /* Pointer to the file */
-    hid_t dxpl_id;                            /* Dataset transfer property list */
-    hid_t lcpl_id;                            /* Link creation property list */
-    H5G_name_t *path;                         /* Path to object being linked */
-    H5O_link_t *lnk;                          /* Pointer to link information to insert */
+    H5F_t *file;                        /* Pointer to the file */
+    hid_t dxpl_id;                      /* Dataset transfer property list */
+    hid_t lcpl_id;                      /* Link creation property list */
+    H5G_name_t *path;                   /* Path to object being linked */
+    H5O_link_t *lnk;                    /* Pointer to link information to insert */
 } H5L_trav_ud2_t;
 
 /* User data for path traversal routine for moving and renaming a link */
 typedef struct {
-    const char *dst_name;                     /* Destination name for moving object */
-    H5T_cset_t cset;                          /* Char set for new name */
-    H5G_loc_t  *dst_loc;		      /* Destination location for moving object */
-    hbool_t copy;                             /* TRUE if this is a copy operation */
-    hid_t lapl_id;                            /* lapl to use in callback */
-    hid_t dxpl_id;                            /* dxpl to use in callback */
+    const char *dst_name;               /* Destination name for moving object */
+    H5T_cset_t cset;                    /* Char set for new name */
+    H5G_loc_t  *dst_loc;		/* Destination location for moving object */
+    hbool_t copy;                       /* TRUE if this is a copy operation */
+    hid_t lapl_id;                      /* lapl to use in callback */
+    hid_t dxpl_id;                      /* dxpl to use in callback */
 } H5L_trav_ud3_t;
 
 /* User data for path traversal routine for getting soft link value */
 typedef struct {
-    size_t size;                              /* Size of user buffer */
-    void *buf;                                /* User buffer */
+    size_t size;                        /* Size of user buffer */
+    void *buf;                          /* User buffer */
 } H5L_trav_ud4_t;
 
 /* User data for path traversal routine for removing link (i.e. unlink) */
 typedef struct {
-    hid_t dxpl_id;                            /* Dataset transfer property list */
+    hid_t dxpl_id;                      /* Dataset transfer property list */
 } H5L_trav_ud5_t;
 
 /* User data for path traversal routine for moving and renaming an object */
 typedef struct {
-    H5F_t *file;                              /* Pointer to the file */
-    H5O_link_t *lnk;                          /* Pointer to link information to insert */
-    hbool_t copy;                             /* TRUE if this is a copy operation */
-    hid_t dxpl_id;                            /* Dataset transfer property list */
+    H5F_t *file;                        /* Pointer to the file */
+    H5O_link_t *lnk;                    /* Pointer to link information to insert */
+    hbool_t copy;                       /* TRUE if this is a copy operation */
+    hid_t dxpl_id;                      /* Dataset transfer property list */
 } H5L_trav_ud6_t;
 
+/* User data for path traversal routine for getting link info by index */
+typedef struct {
+    /* In */
+    H5L_index_t idx_type;               /* Index to use */
+    H5_iter_order_t order;              /* Order to iterate in index */
+    hsize_t n;                          /* Offset of link within index */
+    hid_t dxpl_id;                      /* dxpl to use in callback */
+
+    /* Out */
+    H5L_info_t      *linfo;             /* Buffer to return to user */
+} H5L_trav_ud7_t;
+
 /********************/
 /* Local Prototypes */
 /********************/
 
+static int H5L_find_class_idx(H5L_type_t id);
 static herr_t H5L_link_cb(H5G_loc_t *grp_loc/*in*/, const char *name,
     const H5O_link_t *lnk, H5G_loc_t *obj_loc, void *_udata/*in,out*/,
     H5G_own_loc_t *own_loc/*out*/);
@@ -117,7 +130,12 @@ static herr_t H5L_move_dest_cb(H5G_loc_t *grp_loc/*in*/,
 static herr_t H5L_get_info_cb(H5G_loc_t UNUSED *grp_loc/*in*/, const char UNUSED *name,
     const H5O_link_t *lnk, H5G_loc_t UNUSED *obj_loc, void *_udata/*in,out*/,
     H5G_own_loc_t *own_loc/*out*/);
-static int H5L_find_class_idx(H5L_type_t id);
+static herr_t H5L_get_info_by_idx_cb(H5G_loc_t UNUSED *grp_loc/*in*/, const char UNUSED *name,
+    const H5O_link_t *lnk, H5G_loc_t UNUSED *obj_loc, void *_udata/*in,out*/,
+    H5G_own_loc_t *own_loc/*out*/);
+static herr_t H5L_get_info_by_idx(const H5G_loc_t *loc, const char *group_name,
+    H5L_index_t idx_type, H5_iter_order_t order, hsize_t n,
+    H5L_info_t *linkbuf/*out*/, hid_t lapl_id, hid_t dxpl_id);
 
 /*********************/
 /* Package Variables */
@@ -669,6 +687,11 @@ H5Lget_info(hid_t loc_id, const char *name, H5L_info_t *linkbuf /*out*/,
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a location")
     if(!name || !*name)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no name specified")
+    if(H5P_DEFAULT == lapl_id)
+        lapl_id = H5P_LINK_ACCESS_DEFAULT;
+    else
+        if(TRUE != H5P_isa_class(lapl_id, H5P_LINK_ACCESS))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not link access property list ID")
 
     /* Get the creation time */
     if(H5L_get_info(&loc, name, linkbuf, lapl_id, H5AC_ind_dxpl_id) < 0)
@@ -680,6 +703,54 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5Lget_info_by_idx
+ *
+ * Purpose:	Gets metadata for a link, according to the order within an
+ *              index.
+ *
+ * Return:	Success:	Non-negative with information in LINKBUF
+ * 		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Monday, November  6, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Lget_info_by_idx(hid_t loc_id, const char *group_name,
+    H5L_index_t idx_type, H5_iter_order_t order, hsize_t n,
+    H5L_info_t *linkbuf /*out*/, hid_t lapl_id)
+{
+    H5G_loc_t	loc;
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_API(H5Lget_info_by_idx, FAIL)
+
+    /* Check arguments */
+    if(H5G_loc(loc_id, &loc))
+	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a location")
+    if(!group_name || !*group_name)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no name specified")
+    if(idx_type <= H5L_INDEX_UNKNOWN || idx_type >= H5L_INDEX_N)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid index type specified")
+    if(order <= H5_ITER_UNKNOWN || order >= H5_ITER_N)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid iteration order specified")
+    if(H5P_DEFAULT == lapl_id)
+        lapl_id = H5P_LINK_ACCESS_DEFAULT;
+    else
+        if(TRUE != H5P_isa_class(lapl_id, H5P_LINK_ACCESS))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not link access property list ID")
+
+    /* Get the creation time */
+    if(H5L_get_info_by_idx(&loc, group_name, idx_type, order, n, linkbuf, lapl_id, H5AC_ind_dxpl_id) < 0)
+	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to get link info")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Gget_info_by_idx() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5Lregister
  *
  * Purpose:	Registers a class of user-defined links, or changes the
@@ -716,9 +787,9 @@ H5Lregister(const H5L_class_t *cls)
     if(cls->version != H5L_LINK_CLASS_T_VERS)
       HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid H5L_class_t version number")
 
-    if (cls->id < H5L_TYPE_UD_MIN || cls->id > H5L_TYPE_MAX)
+    if(cls->id < H5L_TYPE_UD_MIN || cls->id > H5L_TYPE_MAX)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid link identification number")
-    if (cls->trav_func == NULL)
+    if(cls->trav_func == NULL)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no traversal function specified")
 
     /* Do it */
@@ -748,7 +819,7 @@ done:
 herr_t
 H5Lunregister(H5L_type_t id)
 {
-    herr_t      ret_value=SUCCEED;       /* Return value */
+    herr_t      ret_value = SUCCEED;       /* Return value */
 
     FUNC_ENTER_API(H5Lunregister, FAIL)
     H5TRACE1("e","Ll",id);
@@ -785,18 +856,18 @@ htri_t
 H5Lis_registered(H5L_type_t id)
 {
     size_t i;                   /* Local index variable */
-    htri_t ret_value=FALSE;     /* Return value */
+    htri_t ret_value = FALSE;     /* Return value */
 
     FUNC_ENTER_API(H5Lis_registered, FAIL)
 
     /* Check args */
-    if(id<0 || id>H5L_TYPE_MAX)
+    if(id < 0 || id > H5L_TYPE_MAX)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid link type id number")
 
     /* Is the link class already registered? */
-    for(i=0; i<H5L_table_used_g; i++)
-	if(H5L_table_g[i].id==id) {
-            ret_value=TRUE;
+    for(i = 0; i < H5L_table_used_g; i++)
+	if(H5L_table_g[i].id == id) {
+            ret_value = TRUE;
             break;
         } /* end if */
 
@@ -832,12 +903,12 @@ static int
 H5L_find_class_idx(H5L_type_t id)
 {
     size_t i;                   /* Local index variable */
-    int ret_value=FAIL;         /* Return value */
+    int ret_value = FAIL;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5L_find_class_idx)
 
-    for (i=0; i<H5L_table_used_g; i++)
-	if (H5L_table_g[i].id == id)
+    for(i = 0; i < H5L_table_used_g; i++)
+	if(H5L_table_g[i].id == id)
 	    HGOTO_DONE((int)i)
 
 done:
@@ -863,16 +934,16 @@ const H5L_class_t *
 H5L_find_class(H5L_type_t id)
 {
     int	idx;                            /* Filter index in global table */
-    H5L_class_t *ret_value=NULL;   /* Return value */
+    H5L_class_t *ret_value = NULL;   /* Return value */
 
     FUNC_ENTER_NOAPI(H5L_find_class, NULL)
 
     /* Get the index in the global table */
-    if((idx=H5L_find_class_idx(id))<0)
+    if((idx = H5L_find_class_idx(id)) < 0)
         HGOTO_ERROR(H5E_LINK, H5E_NOTREGISTERED, NULL, "unable to find link class")
 
     /* Set return value */
-    ret_value=H5L_table_g+idx;
+    ret_value = H5L_table_g+idx;
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -951,25 +1022,25 @@ done:
 herr_t
 H5L_unregister(H5L_type_t id)
 {
-    size_t i;                   /* Local index variable */
-    herr_t ret_value=SUCCEED;   /* Return value */
+    size_t i;                           /* Local index variable */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
-    FUNC_ENTER_NOAPI(H5L_unregister,FAIL)
+    FUNC_ENTER_NOAPI(H5L_unregister, FAIL)
 
-    assert (id>=0 && id<=H5L_TYPE_MAX);
+    HDassert(id >= 0 && id <= H5L_TYPE_MAX);
 
     /* Is the filter already registered? */
-    for (i=0; i<H5L_table_used_g; i++)
-	if (H5L_table_g[i].id==id)
+    for(i = 0; i < H5L_table_used_g; i++)
+	if(H5L_table_g[i].id == id)
             break;
 
     /* Fail if filter not found */
-    if (i>=H5L_table_used_g)
+    if(i >= H5L_table_used_g)
         HGOTO_ERROR(H5E_LINK, H5E_NOTREGISTERED, FAIL, "link class is not registered")
 
     /* Remove filter from table */
     /* Don't worry about shrinking table size (for now) */
-    HDmemmove(&H5L_table_g[i],&H5L_table_g[i+1],sizeof(H5L_class_t)*((H5L_table_used_g-1)-i));
+    HDmemmove(&H5L_table_g[i], &H5L_table_g[i + 1], sizeof(H5L_class_t) * ((H5L_table_used_g - 1) - i));
     H5L_table_used_g--;
 
 done:
@@ -1014,7 +1085,7 @@ H5L_link(H5G_loc_t *new_loc, const char *new_name, H5G_loc_t *obj_loc,
     lnk.u.hard.addr = obj_loc->oloc->addr;
 
     /* Create the link */
-    if( H5L_create_real(new_loc, new_name, obj_loc->path, obj_loc->oloc->file, &lnk, lcpl_id, lapl_id, dxpl_id) <0) 
+    if(H5L_create_real(new_loc, new_name, obj_loc->path, obj_loc->oloc->file, &lnk, lcpl_id, lapl_id, dxpl_id) < 0) 
         HGOTO_ERROR(H5E_LINK, H5E_CANTINIT, FAIL, "unable to create new link to object")
 
 done:
@@ -1113,12 +1184,12 @@ done:
     /* Close the location given to the user callback if it was created */
     if(grp_id >= 0)
     {
-        if(H5I_dec_ref(grp_id) <0)
+        if(H5I_dec_ref(grp_id) < 0)
             HDONE_ERROR(H5E_ATOM, H5E_CANTRELEASE, FAIL, "unable to close atom from UD callback")
     }
     else if(grp != NULL)
     {
-        if(H5G_close(grp) <0)
+        if(H5G_close(grp) < 0)
             HDONE_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "unable to close group given to UD callback")
     }
     else if(temp_loc_init)
@@ -1288,16 +1359,14 @@ H5L_create_hard(H5G_loc_t *cur_loc, const char *cur_name,
 
     /* Create actual link to the object.  Pass in NULL for the path, since this
      * function shouldn't change an object's user path. */
-    if(H5L_create_real(link_loc, link_name, NULL, link_file, &lnk, lcpl_id,
-                       lapl_id, dxpl_id) < 0)
+    if(H5L_create_real(link_loc, link_name, NULL, link_file, &lnk, lcpl_id, lapl_id, dxpl_id) < 0)
         HGOTO_ERROR(H5E_LINK, H5E_CANTINIT, FAIL, "unable to create new link to object")
 
 done:
     /* Free the object header location */
-    if(loc_valid)    {
+    if(loc_valid)
         if(H5G_loc_free(&obj_loc) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CANTRELEASE, FAIL, "unable to free location")
-    }
 
     /* Free the normalized path name */
     if(norm_cur_name)
@@ -1343,8 +1412,7 @@ H5L_create_soft(const char *target_path, H5G_loc_t *link_loc,
     lnk.u.soft.name = norm_target;
 
     /* Create actual link to the object */
-    if(H5L_create_real(link_loc, link_name, NULL, NULL, &lnk, lcpl_id,
-                       lapl_id, dxpl_id) < 0)
+    if(H5L_create_real(link_loc, link_name, NULL, NULL, &lnk, lcpl_id, lapl_id, dxpl_id) < 0)
         HGOTO_ERROR(H5E_LINK, H5E_CANTINIT, FAIL, "unable to create new link to object")
 
 done:
@@ -1405,8 +1473,7 @@ H5L_create_ud(H5G_loc_t *link_loc, const char *link_name, const void * ud_data,
     lnk.type = type;
 
     /* Create actual link to the object */
-    if(H5L_create_real(link_loc, link_name, NULL, NULL, &lnk, lcpl_id,
-                       lapl_id, dxpl_id) < 0)
+    if(H5L_create_real(link_loc, link_name, NULL, NULL, &lnk, lcpl_id, lapl_id, dxpl_id) < 0)
         HGOTO_ERROR(H5E_LINK, H5E_CANTINIT, FAIL, "unable to register new name for object")
 
 done:
@@ -1736,25 +1803,25 @@ H5L_move_dest_cb(H5G_loc_t *grp_loc/*in*/, const char *name,
             {
                 if((link_class->copy_func)(udata->lnk->name, grp_id, udata->lnk->u.ud.udata, udata->lnk->u.ud.size) < 0)
                     HGOTO_ERROR(H5E_LINK, H5E_CALLBACK, FAIL, "UD copy callback returned error")
-            }
+            } /* end if */
             else
             {
                 if((link_class->move_func)(udata->lnk->name, grp_id, udata->lnk->u.ud.udata, udata->lnk->u.ud.size) < 0)
                     HGOTO_ERROR(H5E_LINK, H5E_CALLBACK, FAIL, "UD move callback returned error")
-            }
-        }
-    }
+            } /* end else */
+        } /* end if */
+    } /* end if */
 
 done:
     /* Close the location given to the user callback if it was created */
     if(grp_id >= 0)
     {
-        if(H5I_dec_ref(grp_id) <0)
+        if(H5I_dec_ref(grp_id) < 0)
             HDONE_ERROR(H5E_ATOM, H5E_CANTRELEASE, FAIL, "unable to close atom from UD callback")
     }
     else if(grp != NULL)
     {
-        if(H5G_close(grp) <0)
+        if(H5G_close(grp) < 0)
             HDONE_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "unable to close group given to UD callback")
     }
     else if(temp_loc_init)
@@ -1809,7 +1876,7 @@ H5L_move_cb(H5G_loc_t *grp_loc/*in*/, const char *name, const H5O_link_t *lnk,
     /* Get object type */
     switch(lnk->type) {
         case H5L_TYPE_HARD:
-          if(H5G_UNKNOWN == (type = H5O_obj_type(obj_loc->oloc, udata->dxpl_id)))
+            if(H5G_UNKNOWN == (type = H5O_obj_type(obj_loc->oloc, udata->dxpl_id)))
                 HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "unable to get object type to move")
             break;
 
@@ -1826,6 +1893,7 @@ H5L_move_cb(H5G_loc_t *grp_loc/*in*/, const char *name, const H5O_link_t *lnk,
     /* Set up user data for move_dest_cb */
     if((udata_out.lnk = H5O_copy(H5O_LINK_ID, lnk, NULL)) == NULL)
         HGOTO_ERROR(H5E_LINK, H5E_CANTCOPY, FAIL, "unable to copy link to be moved")
+
     /* In this special case, the link's name is going to be replaced at its
      * destination, so we should free it here.
      */
@@ -1857,10 +1925,10 @@ H5L_move_cb(H5G_loc_t *grp_loc/*in*/, const char *name, const H5O_link_t *lnk,
         if(H5G_obj_remove(grp_loc->oloc, orig_name, &type, udata->dxpl_id) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to remove old name")
         H5RS_decr(dst_name_r);
-    }
+    } /* end if */
 
 done:
-        /* Cleanup */
+    /* Cleanup */
     if(orig_name)
         H5MM_xfree(orig_name);
 
@@ -1875,7 +1943,7 @@ done:
         else if(udata_out.lnk->type >= H5L_TYPE_UD_MIN && udata_out.lnk->u.ud.size > 0)
             udata_out.lnk->u.ud.udata = H5MM_xfree(udata_out.lnk->u.ud.udata);
         H5MM_xfree(udata_out.lnk);
-    }
+    } /* end if */
 
     /* Indicate that this callback didn't take ownership of the group *
      * location for the object */
@@ -1988,14 +2056,13 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5L_get_info_cb(H5G_loc_t UNUSED *grp_loc/*in*/, const char UNUSED *name, const H5O_link_t *lnk,
-    H5G_loc_t UNUSED *obj_loc, void *_udata/*in,out*/, H5G_own_loc_t *own_loc/*out*/)
+H5L_get_info_cb(H5G_loc_t UNUSED *grp_loc/*in*/, const char UNUSED *name,
+    const H5O_link_t *lnk, H5G_loc_t UNUSED *obj_loc, void *_udata/*in,out*/,
+    H5G_own_loc_t *own_loc/*out*/)
 {
     H5L_trav_ud1_t *udata = (H5L_trav_ud1_t *)_udata;   /* User data passed in */
     H5L_info_t *linfo = udata->linfo;
-    const H5L_class_t *link_class;       /* User-defined link class */
-    ssize_t cb_ret;          /* Return value from UD callback */
-    herr_t ret_value = SUCCEED;              /* Return value */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5L_get_info_cb)
 
@@ -2013,34 +2080,39 @@ H5L_get_info_cb(H5G_loc_t UNUSED *grp_loc/*in*/, const char UNUSED *name, const
 
         switch(lnk->type)
         {
-          case H5L_TYPE_HARD:
-              linfo->u.address = lnk->u.hard.addr;
-              break;
-
-          case H5L_TYPE_SOFT:
-              linfo->u.link_size = HDstrlen(lnk->u.soft.name) + 1; /*count the null terminator*/
-              break;
-
-          default:
-            if(lnk->type < H5L_TYPE_UD_MIN || lnk->type > H5L_TYPE_MAX)
-                HGOTO_ERROR(H5E_LINK, H5E_BADTYPE, FAIL, "unknown link class")
-
-            /* User-defined link; call its query function to get the link udata size. */
-            /* Get the link class for this type of link.  It's okay if the class
-            * isn't registered, though--we just can't give any more information
-            * about it
-            */
-              link_class = H5L_find_class(lnk->type);
-
-              if(link_class != NULL && link_class->query_func != NULL) {
-                  if((cb_ret = (link_class->query_func)(lnk->name, lnk->u.ud.udata, lnk->u.ud.size, NULL, (size_t)0)) < 0)
-                    HGOTO_ERROR(H5E_LINK, H5E_CALLBACK, FAIL, "query buffer size callback returned failure")
-
-                  linfo->u.link_size = cb_ret;
-              }
-              else {
-                  linfo->u.link_size = 0;
-              }
+            case H5L_TYPE_HARD:
+                linfo->u.address = lnk->u.hard.addr;
+                break;
+
+            case H5L_TYPE_SOFT:
+                linfo->u.link_size = HDstrlen(lnk->u.soft.name) + 1; /*count the null terminator*/
+                break;
+
+            default:
+            {
+                const H5L_class_t *link_class;      /* User-defined link class */
+
+                if(lnk->type < H5L_TYPE_UD_MIN || lnk->type > H5L_TYPE_MAX)
+                    HGOTO_ERROR(H5E_LINK, H5E_BADTYPE, FAIL, "unknown link class")
+
+                /* User-defined link; call its query function to get the link udata size. */
+                /* Get the link class for this type of link.  It's okay if the class
+                 * isn't registered, though--we just can't give any more information
+                 * about it
+                 */
+                link_class = H5L_find_class(lnk->type);
+
+                if(link_class != NULL && link_class->query_func != NULL) {
+                    ssize_t cb_ret;             /* Return value from UD callback */
+
+                    if((cb_ret = (link_class->query_func)(lnk->name, lnk->u.ud.udata, lnk->u.ud.size, NULL, (size_t)0)) < 0)
+                        HGOTO_ERROR(H5E_LINK, H5E_CALLBACK, FAIL, "query buffer size callback returned failure")
+
+                    linfo->u.link_size = cb_ret;
+                } /* end if */
+                else
+                    linfo->u.link_size = 0;
+            } /* end case */
         } /* end switch */
     } /* end if */
 
@@ -2066,12 +2138,13 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5L_get_info(const H5G_loc_t *loc, const char *name, H5L_info_t *linkbuf/*out*/, hid_t lapl_id, hid_t dxpl_id)
+H5L_get_info(const H5G_loc_t *loc, const char *name,
+    H5L_info_t *linkbuf/*out*/, hid_t lapl_id, hid_t dxpl_id)
 {
-    H5L_trav_ud1_t udata;
-    herr_t ret_value = SUCCEED;       /* Return value */
+    H5L_trav_ud1_t udata;               /* User data for callback */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT(H5L_get_info)
+    FUNC_ENTER_NOAPI(H5L_get_info, FAIL)
 
     udata.linfo = linkbuf;
     udata.dxpl_id = dxpl_id;
@@ -2086,6 +2159,148 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5L_get_info_by_idx_cb
+ *
+ * Purpose:	Callback for retrieving a link's metadata according to an
+ *              index's order.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *              Monday, November  6 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5L_get_info_by_idx_cb(H5G_loc_t UNUSED *grp_loc/*in*/, const char UNUSED *name,
+    const H5O_link_t UNUSED *lnk, H5G_loc_t *obj_loc, void *_udata/*in,out*/,
+    H5G_own_loc_t *own_loc/*out*/)
+{
+    H5L_trav_ud7_t *udata = (H5L_trav_ud7_t *)_udata;   /* User data passed in */
+    H5O_link_t grp_lnk;                 /* Link within group */
+    H5L_info_t *linfo = udata->linfo;
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5L_get_info_by_idx_cb)
+
+#ifdef QAK
+HDfprintf(stderr, "%s: grp_loc = %p\n", FUNC, grp_loc);
+HDfprintf(stderr, "%s: name = %p\n", FUNC, name);
+if(name)
+    HDfprintf(stderr, "%s: name = '%s'\n", FUNC, name);
+HDfprintf(stderr, "%s: lnk = %p\n", FUNC, lnk);
+if(lnk && lnk->name)
+    HDfprintf(stderr, "%s: lnk->name = '%s'\n", FUNC, lnk->name);
+HDfprintf(stderr, "%s: obj_loc = %p\n", FUNC, obj_loc);
+if(obj_loc) {
+    HDfprintf(stderr, "%s: obj_loc->oloc = %p\n", FUNC, obj_loc->oloc);
+    if(obj_loc->oloc)
+        HDfprintf(stderr, "%s: obj_loc->oloc->addr = %a\n", FUNC, obj_loc->oloc->addr);
+} /* end if */
+#endif /* QAK */
+
+    /* Check if the name of the group resolved to a valid object */
+    if(obj_loc == NULL)
+        HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "group doesn't exist")
+
+    /* Query link */
+    if(H5G_obj_lookup_by_idx(obj_loc->oloc, udata->idx_type, udata->order,
+                udata->n, &grp_lnk, udata->dxpl_id) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "link not found")
+
+    /* Get information from the link */
+    if(linfo) {
+        linfo->cset = grp_lnk.cset;
+        linfo->corder = grp_lnk.corder;
+        linfo->corder_valid = grp_lnk.corder_valid;
+        linfo->type = grp_lnk.type;
+
+        switch(grp_lnk.type) {
+            case H5L_TYPE_HARD:
+                linfo->u.address = grp_lnk.u.hard.addr;
+                break;
+
+            case H5L_TYPE_SOFT:
+                linfo->u.link_size = HDstrlen(grp_lnk.u.soft.name) + 1; /*count the null terminator*/
+                break;
+
+            default:
+            {
+                const H5L_class_t *link_class;      /* User-defined link class */
+
+                if(grp_lnk.type < H5L_TYPE_UD_MIN || grp_lnk.type > H5L_TYPE_MAX)
+                    HGOTO_ERROR(H5E_LINK, H5E_BADTYPE, FAIL, "unknown link class")
+
+                /* User-defined link; call its query function to get the link udata size. */
+                /* Get the link class for this type of link.  It's okay if the class
+                 * isn't registered, though--we just can't give any more information
+                 * about it
+                 */
+                link_class = H5L_find_class(grp_lnk.type);
+
+                if(link_class != NULL && link_class->query_func != NULL) {
+                    ssize_t cb_ret;             /* Return value from UD callback */
+
+                    if((cb_ret = (link_class->query_func)(grp_lnk.name, grp_lnk.u.ud.udata, grp_lnk.u.ud.size, NULL, (size_t)0)) < 0)
+                        HGOTO_ERROR(H5E_LINK, H5E_CALLBACK, FAIL, "query buffer size callback returned failure")
+
+                    linfo->u.link_size = cb_ret;
+                } /* end if */
+                else
+                    linfo->u.link_size = 0;
+            } /* end case */
+        } /* end switch */
+    } /* end if */
+
+done:
+    /* Indicate that this callback didn't take ownership of the group *
+     * location for the object */
+    *own_loc = H5G_OWN_NONE;
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5L_get_info_by_idx_cb() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5L_get_info_by_idx
+ *
+ * Purpose:	Returns metadata about a link, according to an order within
+ *              an index.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *              Monday, November  6 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5L_get_info_by_idx(const H5G_loc_t *loc, const char *group_name,
+    H5L_index_t idx_type, H5_iter_order_t order, hsize_t n,
+    H5L_info_t *linkbuf/*out*/, hid_t lapl_id, hid_t dxpl_id)
+{
+    H5L_trav_ud7_t udata;               /* User data for callback */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5L_get_info_by_idx)
+
+    /* Set up user data for callback */
+    udata.idx_type = idx_type;
+    udata.order = order;
+    udata.n = n;
+    udata.dxpl_id = dxpl_id;
+    udata.linfo = linkbuf;
+
+    /* Traverse the group hierarchy to locate the object to get info about */
+    if(H5G_traverse(loc, group_name, H5G_TARGET_SLINK|H5G_TARGET_UDLINK, H5L_get_info_by_idx_cb, &udata, lapl_id, dxpl_id) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_EXISTS, FAIL, "name doesn't exist")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5L_get_info_by_idx() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5L_get_default_lcpl
  *
  * Purpose:	Accessor for the default Link Creation Property List
@@ -2102,7 +2317,7 @@ done:
 hid_t
 H5L_get_default_lcpl(void)
 {
-    hid_t ret_value = FAIL;       /* Return value */
+    hid_t ret_value;            /* Return value */
 
     FUNC_ENTER_NOAPI(H5L_get_default_lcpl, FAIL)
 
diff --git a/src/H5Lpublic.h b/src/H5Lpublic.h
index e944965..eb24375 100644
--- a/src/H5Lpublic.h
+++ b/src/H5Lpublic.h
@@ -120,6 +120,18 @@ typedef struct {
     H5L_query_func_t query_func;    /* Callback for queries                 */
 } H5L_class_t;
 
+/*
+ * The types of indices on links in groups.  Primarily used for "<do> <foo> by
+ * index" routines and for iterating over links in groups.
+ */
+typedef enum H5L_index_t {
+    H5L_INDEX_UNKNOWN = -1,	/* Unknown index type			*/
+    H5L_INDEX_NAME,		/* Index on names of links		*/
+    H5L_INDEX_CORDER,		/* Index on creation order of links	*/
+    H5L_INDEX_N			/* Number of indices defined on links in groups */
+} H5L_index_t;
+
+
 /********************/
 /* Public Variables */
 /********************/
@@ -144,6 +156,9 @@ H5_DLL herr_t H5Lget_val(hid_t loc_id, const char *name, size_t size,
 			      void *buf/*out*/, hid_t lapl_id);
 H5_DLL herr_t H5Lget_info(hid_t loc_id, const char *name,
                               H5L_info_t *linkbuf /*out*/, hid_t lapl_id);
+H5_DLL herr_t H5Lget_info_by_idx(hid_t loc_id, const char *group_name,
+    H5L_index_t idx_type, H5_iter_order_t order, hsize_t n,
+    H5L_info_t *linkbuf /*out*/, hid_t lapl_id);
 
 /* UD link functions */
 H5_DLL herr_t H5Lcreate_ud(hid_t link_loc_id, const char *link_name,
diff --git a/src/H5Plapl.c b/src/H5Plapl.c
index eb3fb1c..e05e4b0 100644
--- a/src/H5Plapl.c
+++ b/src/H5Plapl.c
@@ -119,14 +119,14 @@ const H5P_libclass_t H5P_CLS_LACC[1] = {{
  *              October 31, 2006
  *-------------------------------------------------------------------------
  */
-herr_t
+static herr_t
 H5P_lacc_reg_prop(H5P_genclass_t *pclass)
 {
     size_t nlinks = H5L_ACS_NLINKS_DEF; /* Default number of soft links to traverse */
     char *elink_prefix = H5L_ACS_ELINK_PREFIX_DEF; /* Default external link prefix string */
     herr_t ret_value = SUCCEED;         /* Return value */
 
-    FUNC_ENTER_NOAPI(H5P_lacc_reg_prop, FAIL)
+    FUNC_ENTER_NOAPI_NOINIT(H5P_lacc_reg_prop)
 
     /* Register property for number of links traversed */
     if(H5P_register(pclass, H5L_ACS_NLINKS_NAME, H5L_ACS_NLINKS_SIZE,
diff --git a/src/H5public.h b/src/H5public.h
index e7f4d32..114944a 100644
--- a/src/H5public.h
+++ b/src/H5public.h
@@ -229,9 +229,11 @@ typedef ssize_t			hssize_t;
 
 /* Common iteration orders */
 typedef enum {
+    H5_ITER_UNKNOWN,    /* Unknown order */
     H5_ITER_INC,        /* Increasing order */
     H5_ITER_DEC,        /* Decreasing order */
-    H5_ITER_NATIVE      /* No particular order, whatever is fastest */
+    H5_ITER_NATIVE,     /* No particular order, whatever is fastest */
+    H5_ITER_N		/* Number of iteration orders */
 } H5_iter_order_t;
 
 /* Functions in H5.c */