module/lua/lmem.c

   1 /* BEGIN CSTYLED */
   2 /*
   3 ** $Id: lmem.c,v 1.84.1.1 2013/04/12 18:48:47 roberto Exp $
   4 ** Interface to Memory Manager
   5 ** See Copyright Notice in lua.h
   6 */
   7
   8
   9 #define lmem_c
  10 #define LUA_CORE
  11
  12 #include <sys/lua/lua.h>
  13
  14 #include "ldebug.h"
  15 #include "ldo.h"
  16 #include "lgc.h"
  17 #include "lmem.h"
  18 #include "lobject.h"
  19 #include "lstate.h"
  20
  21
  22
  23 /*
  24 ** About the realloc function:
  25 ** void * frealloc (void *ud, void *ptr, size_t osize, size_t nsize);
  26 ** (`osize' is the old size, `nsize' is the new size)
  27 **
  28 ** * frealloc(ud, NULL, x, s) creates a new block of size `s' (no
  29 ** matter 'x').
  30 **
  31 ** * frealloc(ud, p, x, 0) frees the block `p'
  32 ** (in this specific case, frealloc must return NULL);
  33 ** particularly, frealloc(ud, NULL, 0, 0) does nothing
  34 ** (which is equivalent to free(NULL) in ANSI C)
  35 **
  36 ** frealloc returns NULL if it cannot create or reallocate the area
  37 ** (any reallocation to an equal or smaller size cannot fail!)
  38 */
  39
  40
  41
  42 #define MINSIZEARRAY    4
  43
  44
  45 void *luaM_growaux_ (lua_State *L, void *block, int *size, size_t size_elems,
  46                      int limit, const char *what) {
  47   void *newblock;
  48   int newsize;
  49   if (*size >= limit/2) {  /* cannot double it? */
  50     if (*size >= limit)  /* cannot grow even a little? */
  51       luaG_runerror(L, "too many %s (limit is %d)", what, limit);
  52     newsize = limit;  /* still have at least one free place */
  53   }
  54   else {
  55     newsize = (*size)*2;
  56     if (newsize < MINSIZEARRAY)
  57       newsize = MINSIZEARRAY;  /* minimum size */
  58   }
  59   newblock = luaM_reallocv(L, block, *size, newsize, size_elems);
  60   *size = newsize;  /* update only when everything else is OK */
  61   return newblock;
  62 }
  63
  64
  65 l_noret luaM_toobig (lua_State *L) {
  66   luaG_runerror(L, "memory allocation error: block too big");
  67 }
  68
  69
  70
  71 /*
  72 ** generic allocation routine.
  73 */
  74 void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
  75   void *newblock;
  76   global_State *g = G(L);
  77   size_t realosize = (block) ? osize : 0;
  78   lua_assert((realosize == 0) == (block == NULL));
  79 #if defined(HARDMEMTESTS)
  80   if (nsize > realosize && g->gcrunning)
  81     luaC_fullgc(L, 1);  /* force a GC whenever possible */
  82 #endif
  83   newblock = (*g->frealloc)(g->ud, block, osize, nsize);
  84   if (newblock == NULL && nsize > 0) {
  85     api_check(L, nsize > realosize,
  86                  "realloc cannot fail when shrinking a block");
  87     if (g->gcrunning) {
  88       luaC_fullgc(L, 1);  /* try to free some memory... */
  89       newblock = (*g->frealloc)(g->ud, block, osize, nsize);  /* try again */
  90     }
  91     if (newblock == NULL)
  92       luaD_throw(L, LUA_ERRMEM);
  93   }
  94   lua_assert((nsize == 0) == (newblock == NULL));
  95   g->GCdebt = (g->GCdebt + nsize) - realosize;
  96   return newblock;
  97 }
  98 /* END CSTYLED */