bk commit into 4.1 tree (serg:1.2390)

[serg]

Below is the list of changes that have just been committed into a local
4.1 repository of serg. When serg does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
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ChangeSet
  1.2390 05/08/24 23:07:06 serg@stripped +1 -0
  memroot: trash the memory in free_root()

  mysys/my_alloc.c
    1.25 05/08/24 23:07:01 serg@stripped +14 -1
    memroot: trash the memory in free_root()

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	serg
# Host:	sergbook.mysql.com
# Root:	/usr/home/serg/Abk/mysql-4.1

--- 1.24/mysys/my_alloc.c	Tue Oct 26 20:29:54 2004
+++ 1.25/mysys/my_alloc.c	Wed Aug 24 23:07:01 2005
@@ -203,7 +203,7 @@
     next->left= get_size-ALIGN_SIZE(sizeof(USED_MEM));
     *prev=next;
   }
-    
+
   point= (gptr) ((char*) next+ (next->size-next->left));
   /*TODO: next part may be unneded due to mem_root->first_block_usage counter*/
   if ((next->left-= Size) < mem_root->min_malloc)
@@ -217,6 +217,12 @@
 #endif
 }
 
+#ifdef SAFEMALLOC
+#define TRASH(X) bfill(((char*)(X) + ((X)->size-(X)->left)), (X)->left, 0xa5)
+#else
+#define TRASH /* no-op */
+#endif
+
 /* Mark all data in blocks free for reusage */
 
 static inline void mark_blocks_free(MEM_ROOT* root)
@@ -227,14 +233,20 @@
   /* iterate through (partially) free blocks, mark them free */
   last= &root->free;
   for (next= root->free; next; next= *(last= &next->next))
+  {
     next->left= next->size - ALIGN_SIZE(sizeof(USED_MEM));
+    TRASH(next);
+  }
 
   /* Combine the free and the used list */
   *last= next=root->used;
 
   /* now go through the used blocks and mark them free */
   for (; next; next= next->next)
+  {
     next->left= next->size - ALIGN_SIZE(sizeof(USED_MEM));
+    TRASH(next);
+  }
 
   /* Now everything is set; Indicate that nothing is used anymore */
   root->used= 0;
@@ -280,6 +292,7 @@
   {
     root->free=root->pre_alloc;
     root->free->left=root->pre_alloc->size-ALIGN_SIZE(sizeof(USED_MEM));
+    TRASH(root->pre_alloc);
     root->free->next=0;
   }
   root->block_num= 4;