[svn-r19283] Description:

	Bring r19278 from trunk to 1.8 branch:

	More fixes to memory allocation, etc. exposed by valgrind.

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
   Mac OS X/32 10.6.4 (amazon) in debug mode
   Mac OS X/32 10.6.4 (amazon) w/C++ & FORTRAN, w/threadsafe,
       in production mode
   Mac OS X/32 10.6.4 (amazon) w/parallel, in debug mode

1 files changed, 10 insertions, 4 deletions

diff --git a/src/H5HLcache.c b/src/H5HLcache.c
index 6c5c5d2..01532ca 100644
--- a/src/H5HLcache.c
+++ b/src/H5HLcache.c
@@ -438,10 +438,16 @@ H5HL_prefix_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr,
 
         /* Check if the local heap is a single object in cache */
         if(heap->single_cache_obj) {
-            /* Set p to the start of the data block.  This is necessary because
-             * there may be a gap between the used portion of the prefix and the
-             * data block due to alignment constraints. */
-            p = buf + heap->prfx_size;
+            if((p - buf) < heap->prfx_size) {
+                size_t gap;         /* Size of gap between prefix and data block */
+
+                /* Set p to the start of the data block.  This is necessary because
+                 * there may be a gap between the used portion of the prefix and the
+                 * data block due to alignment constraints. */
+                gap = heap->prfx_size - (p - buf);
+                HDmemset(p, 0, gap);
+                p += gap;
+            } /* end if */
 
             /* Serialize the free list into the heap data's image */
             H5HL_fl_serialize(heap);