[svn-r19126] Description:

	Bring r19124 from trunk to 1.8 branch:

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

Tested on:
       FreeBSD/32 6.3 (duty) in debug mode
	(h5committest performed on trunk)

2 files changed, 21 insertions, 6 deletions

diff --git a/configure b/configure
index a55a709..aceee30 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.in Id: configure.in 19077 2010-07-16 16:41:22Z nfortne2 .
+# From configure.in Id: configure.in 19100 2010-07-19 18:38:40Z koziol .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.65 for HDF5 1.8.5-snap5.
 #
diff --git a/src/H5Fsuper.c b/src/H5Fsuper.c
index 4275069..0469f8a 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)