Commit 961abf79 authored by unknown's avatar unknown
Browse files

memroot: trash the memory in free_root()

parent 43da0a41

mysys/my_alloc.c

+14 −1
Original line number Diff line number Diff line
@@ -217,6 +217,12 @@ gptr alloc_root(MEM_ROOT *mem_root,unsigned int Size) 
#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 @@ static inline void mark_blocks_free(MEM_ROOT* root) 
  /* 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 @@ void free_root(MEM_ROOT *root, myf MyFlags) 
  {

    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;