module/lua/lmem.c

   1 /*
   2 ** $Id: lmem.c,v 1.84.1.1 2013/04/12 18:48:47 roberto Exp $
   3 ** Interface to Memory Manager
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #define lmem_c
   9 #define LUA_CORE
  10
  11 #include <sys/lua/lua.h>
  12
  13 #include "ldebug.h"
  14 #include "ldo.h"
  15 #include "lgc.h"
  16 #include "lmem.h"
  17 #include "lobject.h"
  18 #include "lstate.h"
  19
  20
  21
  22 /*
  23 ** About the realloc function:
  24 ** void * frealloc (void *ud, void *ptr, size_t osize, size_t nsize);
  25 ** (`osize' is the old size, `nsize' is the new size)
  26 **
  27 ** * frealloc(ud, NULL, x, s) creates a new block of size `s' (no
  28 ** matter 'x').
  29 **
  30 ** * frealloc(ud, p, x, 0) frees the block `p'
  31 ** (in this specific case, frealloc must return NULL);
  32 ** particularly, frealloc(ud, NULL, 0, 0) does nothing
  33 ** (which is equivalent to free(NULL) in ANSI C)
  34 **
  35 ** frealloc returns NULL if it cannot create or reallocate the area
  36 ** (any reallocation to an equal or smaller size cannot fail!)
  37 */
  38
  39
  40
  41 #define MINSIZEARRAY    4
  42
  43
  44 void *luaM_growaux_ (lua_State *L, void *block, int *size, size_t size_elems,
  45                      int limit, const char *what) {
  46   void *newblock;
  47   int newsize;
  48   if (*size >= limit/2) {  /* cannot double it? */
  49     if (*size >= limit)  /* cannot grow even a little? */
  50       luaG_runerror(L, "too many %s (limit is %d)", what, limit);
  51     newsize = limit;  /* still have at least one free place */
  52   }
  53   else {
  54     newsize = (*size)*2;
  55     if (newsize < MINSIZEARRAY)
  56       newsize = MINSIZEARRAY;  /* minimum size */
  57   }
  58   newblock = luaM_reallocv(L, block, *size, newsize, size_elems);
  59   *size = newsize;  /* update only when everything else is OK */
  60   return newblock;
  61 }
  62
  63
  64 l_noret luaM_toobig (lua_State *L) {
  65   luaG_runerror(L, "memory allocation error: block too big");
  66 }
  67
  68
  69
  70 /*
  71 ** generic allocation routine.
  72 */
  73 void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
  74   void *newblock;
  75   global_State *g = G(L);
  76   size_t realosize = (block) ? osize : 0;
  77   lua_assert((realosize == 0) == (block == NULL));
  78 #if defined(HARDMEMTESTS)
  79   if (nsize > realosize && g->gcrunning)
  80     luaC_fullgc(L, 1);  /* force a GC whenever possible */
  81 #endif
  82   newblock = (*g->frealloc)(g->ud, block, osize, nsize);
  83   if (newblock == NULL && nsize > 0) {
  84     api_check(L, nsize > realosize,
  85                  "realloc cannot fail when shrinking a block");
  86     if (g->gcrunning) {
  87       luaC_fullgc(L, 1);  /* try to free some memory... */
  88       newblock = (*g->frealloc)(g->ud, block, osize, nsize);  /* try again */
  89     }
  90     if (newblock == NULL)
  91       luaD_throw(L, LUA_ERRMEM);
  92   }
  93   lua_assert((nsize == 0) == (newblock == NULL));
  94   g->GCdebt = (g->GCdebt + nsize) - realosize;
  95   return newblock;
  96 }