`free' gets size of the block: complete control over memory use

lmem.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lmem.c,v 1.40 2000/11/24 17:39:56 roberto Exp roberto $
+** $Id: lmem.c,v 1.41 2000/12/26 18:46:09 roberto Exp roberto $
 ** Interface to Memory Manager
 ** See Copyright Notice in lua.h
 */
@@ -29,15 +29,14 @@
 #include <limits.h>
 #include <string.h>
 
-#define realloc(b, s)	debug_realloc(b, s)
-#define malloc(b)	debug_realloc(NULL, b)
-#define free(b)		debug_realloc(b, 0)
+#define basicrealloc(b, os, s)	debug_realloc(b, os, s)
+#define basicfree(b, s)		debug_realloc(b, s, 0)
 
 
 /* ensures maximum alignment for HEADER */
 #define HEADER	(sizeof(union L_Umaxalign))
 
-#define MARKSIZE	16
+#define MARKSIZE	32
 #define MARK		0x55  /* 01010101 (a nice pattern) */
 
 
@@ -55,8 +54,6 @@ static void *checkblock (void *block) {
   int i;
   for (i=0;i<MARKSIZE;i++)
     assert(*(((char *)b)+HEADER+size+i) == MARK+i);  /* corrupted block? */
-  memdebug_numblocks--;
-  memdebug_total -= size;
   return b;
 }
 
@@ -66,12 +63,15 @@ static void freeblock (void *block) {
     size_t size = *blocksize(block);
     block = checkblock(block);
     memset(block, -1, size+HEADER+MARKSIZE);  /* erase block */
-    (free)(block);  /* free original block */
+    free(block);  /* free original block */
+    memdebug_numblocks--;
+    memdebug_total -= size;
   }
 }
 
 
-static void *debug_realloc (void *block, size_t size) {
+static void *debug_realloc (void *block, size_t oldsize, size_t size) {
+  assert((oldsize == 0) ? block == NULL : oldsize == *blocksize(block));
   if (size == 0) {
     freeblock(block);
     return NULL;
@@ -79,19 +79,22 @@ static void *debug_realloc (void *block, size_t size) {
   else if (memdebug_total+size > memdebug_memlimit)
     return NULL;  /* to test memory allocation errors */
   else {
-    size_t realsize = HEADER+size+MARKSIZE;
-    char *newblock = (char *)(malloc)(realsize);  /* alloc a new block */
+    char *newblock;
     int i;
+    size_t realsize = HEADER+size+MARKSIZE;
     if (realsize < size) return NULL;  /* overflow! */
+    newblock = (char *)malloc(realsize);  /* alloc a new block */
     if (newblock == NULL) return NULL;
+    if (oldsize > size) oldsize = size;
     if (block) {
-      size_t oldsize = *blocksize(block);
-      if (oldsize > size) oldsize = size;
       memcpy(newblock+HEADER, block, oldsize);
       freeblock(block);  /* erase (and check) old copy */
     }
+    /* initialize new part of the block with something `weird' */
+    memset(newblock+HEADER+oldsize, -MARK, size-oldsize);
     memdebug_total += size;
-    if (memdebug_total > memdebug_maxmem) memdebug_maxmem = memdebug_total;
+    if (memdebug_total > memdebug_maxmem)
+      memdebug_maxmem = memdebug_total;
     memdebug_numblocks++;
     *(size_t *)newblock = size;
     for (i=0;i<MARKSIZE;i++)
@@ -102,20 +105,26 @@ static void *debug_realloc (void *block, size_t size) {
 
 
 /* }====================================================================== */
-#endif
-
 
+#else
+/* no debug */
 
 /*
 ** Real ISO (ANSI) systems do not need these tests;
 ** but some systems (Sun OS) are not that ISO...
 */
 #ifdef OLD_ANSI
-#define realloc(b,s)	((b) == NULL ? malloc(s) : (realloc)(b, s))
-#define free(b)		if (b) (free)(b)
+#define basicrealloc(b,os,s)	((b) == NULL ? malloc(s) : realloc(b, s))
+#define basicfree(b,s)		if (b) free(b)
+#else
+#define basicrealloc(b,os,s)	realloc(b,s)
+#define basicfree(b,s)		free(b)
+
 #endif
 
 
+#endif
+
 void *luaM_growaux (lua_State *L, void *block, int *size, int size_elems,
                     int limit, const char *errormsg) {
   void *newblock;
@@ -127,7 +136,8 @@ void *luaM_growaux (lua_State *L, void *block, int *size, int size_elems,
       newsize = limit;  /* still have at least MINPOWER2 free places */
     else lua_error(L, errormsg);
   }
-  newblock = luaM_realloc(L, block, (luint32)newsize*(luint32)size_elems);
+  newblock = luaM_realloc(L, block, (luint32)(*size)*(luint32)size_elems,
+                                    (luint32)newsize*(luint32)size_elems);
   *size = newsize;  /* update only when everything else is OK */
   return newblock;
 }
@@ -136,20 +146,25 @@ void *luaM_growaux (lua_State *L, void *block, int *size, int size_elems,
 /*
 ** generic allocation routine.
 */
-void *luaM_realloc (lua_State *L, void *block, luint32 size) {
+void *luaM_realloc (lua_State *L, void *block, luint32 oldsize, luint32 size) {
   if (size == 0) {
-    free(block);  /* block may be NULL; that is OK for free */
-    return NULL;
+    basicfree(block, oldsize);  /* block may be NULL; that is OK for free */
+    block = NULL;
   }
   else if (size >= MAX_SIZET)
     lua_error(L, "memory allocation error: block too big");
-  block = realloc(block, size);
-  if (block == NULL) {
-    if (L)
-      luaD_breakrun(L, LUA_ERRMEM);  /* break run without error message */
-    else return NULL;  /* error before creating state! */
+  else {
+    block = basicrealloc(block, oldsize, size);
+    if (block == NULL) {
+      if (L)
+        luaD_breakrun(L, LUA_ERRMEM);  /* break run without error message */
+      else return NULL;  /* error before creating state! */
+    }
+  }
+  if (L) {
+    L->nblocks -= oldsize;
+    L->nblocks += size;
   }
   return block;
 }
 
-