unwind-dw2-fde-glibc.c (_Unwind_IteratePhdrCallback): Guard against…

unwind-dw2-fde-glibc.c (_Unwind_IteratePhdrCallback): Guard against prev_cache_entry == NULL when moving a cache entry to the head of...

2005-12-15  Andrew Haley  <aph@redhat.com>

        * unwind-dw2-fde-glibc.c (_Unwind_IteratePhdrCallback): Guard
        against prev_cache_entry == NULL when moving a cache entry to the
        head of the list.

From-SVN: r108582

gcc/ChangeLog

+2005-12-15  Andrew Haley  <aph@redhat.com>
+
+	* unwind-dw2-fde-glibc.c (_Unwind_IteratePhdrCallback): Guard
+	against prev_cache_entry == NULL when moving a cache entry to the
+	head of the list.
+	
 2005-12-15  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* config/mt/mt.c (mt_override_options): Require lower case

gcc/unwind-dw2-fde-glibc.c

@@ -257,7 +257,10 @@ _Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
 
   if (size >= sizeof (struct ext_dl_phdr_info))
     {
-      if (last_cache_entry != NULL)
+      /* Move the cache entry we're about to overwrite to the head of
+	 the list.  If either last_cache_entry or prev_cache_entry are
+	 NULL, that cache entry is already at the head.  */
+      if (last_cache_entry != NULL && prev_cache_entry != NULL)
 	{
 	  prev_cache_entry->link = last_cache_entry->link;
 	  last_cache_entry->link = frame_hdr_cache_head;