[svn-r12528] Added User-Defined links to the library.

Users can create external links using H5L_create_external().  These links
point to an object in another HDF5 file.  Users can alter the behavior of
external links or create new kinds of links by registering callbacks
using the H5L interface.

Added tests, tools support, etc.

Also a number of other, minor changes have been made (some restructuring of
the H5L interface, for instance).

Additional documentation and examples are forthcoming.

1 files changed, 85 insertions, 0 deletions

diff --git a/tools/lib/h5diff.c b/tools/lib/h5diff.c
index e8c546e..4fed814 100644
--- a/tools/lib/h5diff.c
+++ b/tools/lib/h5diff.c
@@ -870,6 +870,7 @@ hsize_t diff_compare (hid_t file1_id,
  *  H5G_DATASET  Object is a dataset
  *  H5G_TYPE     Object is a named data type
  *  H5G_LINK     Object is a symbolic link
+ *  H5G_UDLINK   Object is a user-defined link
  *
  * Return: Number of differences found
  *
@@ -1067,6 +1068,90 @@ hsize_t diff (hid_t file1_id,
   }
   break;
 
+ /*-------------------------------------------------------------------------
+  * H5G_UDLINK
+  *-------------------------------------------------------------------------
+  */
+ case H5G_UDLINK:
+  {
+   char *buf1 = NULL;
+   char *buf2 = NULL;
+   H5L_linkinfo_t li1;
+   H5L_linkinfo_t li2;
+
+   if (H5Lget_linkinfo (file1_id, path1, &li1, H5P_DEFAULT) < 0)
+    goto out;
+   if (H5Lget_linkinfo (file1_id, path1, &li2, H5P_DEFAULT) < 0)
+    goto out;
+
+   /* Only external links will have a query function registered */
+   if(li1.linkclass == H5L_LINK_EXTERNAL && li2.linkclass == H5L_LINK_EXTERNAL)
+   {
+      buf1 = HDmalloc (li1.u.link_size);
+      buf2 = HDmalloc (li2.u.link_size);
+
+      if (H5Lget_linkval (file1_id, path1, li1.u.link_size, buf1, H5P_DEFAULT) < 0)
+      {
+        HDfree (buf1); HDfree (buf2);
+        goto out;
+      }
+      if (H5Lget_linkval (file2_id, path2, li2.u.link_size, buf2, H5P_DEFAULT) < 0)
+      {
+        HDfree (buf1); HDfree (buf2);
+        goto out;
+      }
+
+      /* If the buffers are the same size, compare them */
+      if(li1.u.link_size == li2.u.link_size)
+      {
+        if (H5Lget_linkval (file1_id, path1, li1.u.link_size, buf1, H5P_DEFAULT) < 0)
+        {
+          HDfree (buf1); HDfree (buf2);
+          goto out;
+        }
+        if (H5Lget_linkval (file2_id, path2, li2.u.link_size, buf2, H5P_DEFAULT) < 0)
+        {
+          HDfree (buf1); HDfree (buf2);
+          goto out;
+        }
+        ret = HDmemcmp (buf1, buf2, li1.u.link_size);
+      }
+      else
+        ret = 1;
+
+      /* if "buf1" != "buf2" then the links are "different" */
+      nfound = (ret != 0) ? 1 : 0;
+
+      if (print_objname (options, nfound))
+        parallel_print("External Link:        <%s> and <%s>\n", path1, path2);
+   }
+   else
+   {
+      /* If one or both of these links isn't an external link, we can only
+       * compare information from H5Lget_linkinfo since we don't have a query
+       * function registered for them. */
+
+      /* If the link classes or the buffer length are not the
+       * same, the links are "different"
+       */
+      if((li1.linkclass != li2.linkclass) || (li1.u.link_size != li2.u.link_size))
+        nfound = 1;
+      else
+        nfound = 0;
+
+      if (print_objname (options, nfound))
+        parallel_print("User-defined Link:        <%s> and <%s>\n", path1, path2);
+   }
+
+   /* always print the number of differences found in verbose mode */
+   if (options->m_verbose)
+    print_found(nfound);
+
+   HDfree (buf1);
+   HDfree (buf2);
+  }
+  break;
+
  default:
   nfound = 0;
   if (options->m_verbose)