Change memcheck's (client) realloc implementation so that it copies

and moves the block even when the new size is smaller or the same.
This increases the chance that it can detect buggy code which assumes
that realloc-smaller doesn't cause the block to move.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@8454

diff --git a/memcheck/mc_malloc_wrappers.c b/memcheck/mc_malloc_wrappers.c
index 8ccbbc3bfe25a49655ae828e426a0499ca32dd53..cfc1e57ac57fabd79d08cf05b4c5f6a9d7c1869e 100644 (file)
--- a/memcheck/mc_malloc_wrappers.c
+++ b/memcheck/mc_malloc_wrappers.c
@@ -372,24 +372,45 @@ void* MC_(realloc) ( ThreadId tid, void* p_old, SizeT new_szB )
 
    old_szB = mc->szB;
 
-   if (old_szB == new_szB) {
-      /* size unchanged */
-      mc->where = VG_(record_ExeContext)(tid, 0/*first_ip_delta*/);
-      p_new = p_old;
-      
-   } else if (old_szB > new_szB) {
-      /* new size is smaller */
-      MC_(make_mem_noaccess)( mc->data+new_szB, mc->szB-new_szB );
-      mc->szB = new_szB;
-      mc->where = VG_(record_ExeContext)(tid, 0/*first_ip_delta*/);
-      p_new = p_old;
-      /* Possibly fill freed area with specified junk. */
-      if (MC_(clo_free_fill) != -1) {
-         tl_assert(MC_(clo_free_fill) >= 0x00 && MC_(clo_free_fill) <= 0xFF);
-         VG_(memset)((void*)(mc->data+new_szB), MC_(clo_free_fill), 
-                                                old_szB-new_szB);
+   if (new_szB <= old_szB) {
+      /* new size is smaller or the same */
+      Addr a_new; 
+      /* Get new memory */
+      a_new = (Addr)VG_(cli_malloc)(VG_(clo_alignment), new_szB);
+
+      if (a_new) {
+         ExeContext* ec;
+
+         ec = VG_(record_ExeContext)(tid, 0/*first_ip_delta*/);
+         tl_assert(ec);
+
+         /* Retained part is copied, red zones set as normal */
+         MC_(make_mem_noaccess)( a_new-MC_MALLOC_REDZONE_SZB, 
+                                 MC_MALLOC_REDZONE_SZB );
+         MC_(copy_address_range_state) ( (Addr)p_old, a_new, new_szB );
+         MC_(make_mem_noaccess)        ( a_new+new_szB, MC_MALLOC_REDZONE_SZB );
+
+         /* Copy from old to new */
+         VG_(memcpy)((void*)a_new, p_old, new_szB);
+
+         /* Possibly fill freed area with specified junk. */
+         if (MC_(clo_free_fill) != -1) {
+            tl_assert(MC_(clo_free_fill) >= 0x00 && MC_(clo_free_fill) <= 0xFF);
+            VG_(memset)((void*)p_old, MC_(clo_free_fill), old_szB);
+         }
+
+         /* Free old memory */
+         /* Nb: we have to allocate a new MC_Chunk for the new memory rather
+            than recycling the old one, so that any erroneous accesses to the
+            old memory are reported. */
+         die_and_free_mem ( tid, mc, MC_MALLOC_REDZONE_SZB );
+
+         // Allocate a new chunk.
+         mc = create_MC_Chunk( ec, a_new, new_szB, MC_AllocMalloc );
       }
 
+      p_new = (void*)a_new;
+
    } else {
       /* new size is bigger */
       Addr a_new;