[svn-r8607] Purpose: bug fix.

Description:  After an opaque datatype is created, if no tag is attached, some operations will have
trouble to deal with null string of tag.

Solution:  Initialize opaque's tag as empty string when it's created.

Platforms tested:  h5committest.

1 files changed, 8 insertions, 3 deletions

diff --git a/src/H5T.c b/src/H5T.c
index 11e7899..7a50308 100644
--- a/src/H5T.c
+++ b/src/H5T.c
@@ -2616,8 +2616,12 @@ H5T_create(H5T_class_t type, size_t size)
             dt->type = type;
             if(type==H5T_COMPOUND)
                 dt->u.compnd.packed=TRUE;       /* Start out packed */
-            break;
+            else if(type==H5T_OPAQUE)
+                /* Initialize the tag in case it's not set later.  A null tag will 
+                 * cause problems for later operations. */
+                dt->u.opaque.tag = H5MM_strdup("");
 
+            break;
         case H5T_ENUM:
             if (sizeof(char)==size) {
                 subtype = H5T_NATIVE_SCHAR_g;
@@ -3637,8 +3641,9 @@ H5T_cmp(const H5T_t *dt1, const H5T_t *dt2)
             break;
 
         case H5T_OPAQUE:
-            HGOTO_DONE(HDstrcmp(dt1->u.opaque.tag,dt2->u.opaque.tag));
-
+            if(dt1->u.opaque.tag && dt2->u.opaque.tag) {
+                HGOTO_DONE(HDstrcmp(dt1->u.opaque.tag,dt2->u.opaque.tag));
+            } 
         case H5T_ARRAY:
             if (dt1->u.array.ndims < dt2->u.array.ndims)
                 HGOTO_DONE(-1);