[mmalloc] Use mremap to expand heaps (heap collision prevention)

[simgrid.git] / src / xbt / mmalloc / mmorecore.c

diff --git a/src/xbt/mmalloc/mmorecore.c b/src/xbt/mmalloc/mmorecore.c
index 014b8b8..f47c539 100644 (file)
--- a/src/xbt/mmalloc/mmorecore.c
+++ b/src/xbt/mmalloc/mmorecore.c
@@ -1,7 +1,4 @@
-/* Support for an sbrk-like function that uses mmap.
-   Copyright 1992, 2000 Free Software Foundation, Inc.
-
-   Contributed by Fred Fish at Cygnus Support.   fnf@cygnus.com */
+/* Support for an sbrk-like function that uses mmap. */
 
 /* Copyright (c) 2010-2014. The SimGrid Team.
  * All rights reserved.                                                     */
@@ -9,9 +6,9 @@
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
 
-#ifndef MAP_ANONYMOUS
-#define MAP_ANONYMOUS MAP_ANON
-#endif
+/* Copyright 1992, 2000 Free Software Foundation, Inc.
+
+   Contributed by Fred Fish at Cygnus Support.   fnf@cygnus.com */
 
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>             /* Prototypes for lseek */
@@ -23,6 +20,10 @@
 
 #include "mmprivate.h"
 
+#ifndef MAP_ANONYMOUS
+#define MAP_ANONYMOUS MAP_ANON
+#endif
+
 #define PAGE_ALIGN(addr) (void*) (((long)(addr) + xbt_pagesize - 1) &   \
                                   ~((long)xbt_pagesize - 1))
 
@@ -108,9 +109,14 @@ void *mmorecore(struct mdesc *mdp, ssize_t size)
 
       /* Let's call mmap. Note that it is possible that mdp->top
          is 0. In this case mmap will choose the address for us */
-      mapto = mmap(mdp->top, mapbytes, PROT_READ | PROT_WRITE,
+      if(mdp->base==mdp->top)
+        mapto = mmap(mdp->top, mapbytes, PROT_READ | PROT_WRITE,
                    MAP_PRIVATE_OR_SHARED(mdp) | MAP_IS_ANONYMOUS(mdp) |
                    MAP_FIXED, MAP_ANON_OR_FD(mdp), foffset);
+      else {
+        size_t old_size = (char*)mdp->top - (char*)mdp->base;
+        mapto = mremap(mdp->base, old_size, old_size+size, 0);
+      }
 
       if (mapto == (void *) -1/* That's MAP_FAILED */) {
         char buff[1024];
@@ -123,9 +129,6 @@ void *mmorecore(struct mdesc *mdp, ssize_t size)
         abort();
       }
 
-      if (mdp->top == 0)
-        mdp->base = mdp->breakval = mapto;
-
       mdp->top = PAGE_ALIGN((char *) mdp->breakval + size);
       result = (void *) mdp->breakval;
       mdp->breakval = (char *) mdp->breakval + size;