[svn-r19124] Description:

	Add some error checking to the process of creating superblock extension.

Tested on:
        FreeBSD/32 6.3 (duty) in debug mode
        FreeBSD/64 6.3 (liberty) w/C++ & FORTRAN, in debug mode
        Linux/32 2.6 (jam) w/PGI compilers, w/default API=1.8.x,
                w/C++ & FORTRAN, w/threadsafe, in debug mode
        Linux/64-amd64 2.6 (amani) w/Intel compilers, w/default API=1.6.x,
                w/C++ & FORTRAN, in production mode
        Solaris/32 2.10 (linew) w/deprecated symbols disabled, w/C++ & FORTRAN,
                w/szip filter, w/threadsafe, in production mode
        Linux/PPC 2.6 (heiwa) w/C++ & FORTRAN, w/threadsafe, in debug mode
        Linux/64-ia64 2.6 (cobalt) w/Intel compilers, w/C++ & FORTRAN,
                in production mode
        Linux/64-amd64 2.6 (abe) w/parallel, w/FORTRAN, in debug mode

1 files changed, 20 insertions, 5 deletions

diff --git a/src/H5Fsuper.c b/src/H5Fsuper.c
index f9b6b0c..a259dde 100644
--- a/src/H5Fsuper.c
+++ b/src/H5Fsuper.c
@@ -189,12 +189,27 @@ H5F_super_ext_create(H5F_t *f, hid_t dxpl_id, H5O_loc_t *ext_ptr)
     HDassert(!H5F_addr_defined(f->shared->sblock->ext_addr));
     HDassert(ext_ptr);
 
-    H5O_loc_reset(ext_ptr);
-    if(H5O_create(f, dxpl_id, 0, H5P_GROUP_CREATE_DEFAULT, ext_ptr) < 0)
-	HGOTO_ERROR(H5E_OHDR, H5E_CANTCREATE, FAIL, "unable to create superblock extension")
+    /* Check for older version of superblock format that can't support superblock extensions */
+    if(f->shared->sblock->super_vers < HDF5_SUPERBLOCK_VERSION_2)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTCREATE, FAIL, "superblock extension not permitted with version %u of superblock", f->shared->sblock->super_vers)
+    else if(H5F_addr_defined(f->shared->sblock->ext_addr))
+        HGOTO_ERROR(H5E_FILE, H5E_CANTCREATE, FAIL, "superblock extension already exists?!?!")
+    else {
+        /* The superblock extension isn't actually a group, but the
+         * default group creation list should work fine.
+         * If we don't supply a size for the object header, HDF5 will
+         * allocate H5O_MIN_SIZE by default.  This is currently
+         * big enough to hold the biggest possible extension, but should
+         * be tuned if more information is added to the superblock
+         * extension.
+         */
+        H5O_loc_reset(ext_ptr);
+        if(H5O_create(f, dxpl_id, 0, H5P_GROUP_CREATE_DEFAULT, ext_ptr) < 0)
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTCREATE, FAIL, "unable to create superblock extension")
 
-    /* Record the address of the superblock extension */
-    f->shared->sblock->ext_addr = ext_ptr->addr;
+        /* Record the address of the superblock extension */
+        f->shared->sblock->ext_addr = ext_ptr->addr;
+    } /* end else */
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)