Merge pull request #1348 in HDFFV/hdf5 from ~SONGYULU/hdf5_ray:bugfix/HDFFV-10635-hdf5-library-segmentation-fault to develop

* commit '3e8599591504c95d8a97100b9546174f6132dc97':
  HDFFV-10635: Some minor changes to the test case and the comments in the library.
  HDFFV-10635: add a test case.
  HDFFV-10635: Allowing to write the same variable-length element more than once.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/H5HG.c b/src/H5HG.c
index b9d8dc3..df1c82d 100644
--- a/src/H5HG.c
+++ b/src/H5HG.c
@@ -785,7 +785,14 @@ H5HG_remove (H5F_t *f, H5HG_t *hobj)
         HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, FAIL, "unable to protect global heap")
 
     HDassert(hobj->idx < heap->nused);
-    HDassert(heap->obj[hobj->idx].begin);
+    
+    /* When the application selects the same location to rewrite the VL element by using H5Sselect_elements,
+     * it can happen that the entry has been removed by first rewrite.  Here we simply skip the removal of
+     * the entry and let the second rewrite happen (see HDFFV-10635).  In the future, it'd be nice to handle
+     * this situation in H5T_conv_vlen in H5Tconv.c instead of this level (HDFFV-10648). */
+    if(heap->obj[hobj->idx].nrefs == 0 && heap->obj[hobj->idx].size == 0 && !heap->obj[hobj->idx].begin)
+        HGOTO_DONE(ret_value)
+        
     obj_start = heap->obj[hobj->idx].begin;
     /* Include object header size */
     need = H5HG_ALIGN(heap->obj[hobj->idx].size) + H5HG_SIZEOF_OBJHDR(f);