lmem.c revision 344220 
1/*
2** $Id: lmem.c,v 1.91.1.1 2017/04/19 17:20:42 roberto Exp $
3** Interface to Memory Manager
4** See Copyright Notice in lua.h
5*/
6
7#define lmem_c
8#define LUA_CORE
9
10#include "lprefix.h"
11
12
13#include <stddef.h>
14
15#include "lua.h"
16
17#include "ldebug.h"
18#include "ldo.h"
19#include "lgc.h"
20#include "lmem.h"
21#include "lobject.h"
22#include "lstate.h"
23
24
25
26/*
27** About the realloc function:
28** void * frealloc (void *ud, void *ptr, size_t osize, size_t nsize);
29** ('osize' is the old size, 'nsize' is the new size)
30**
31** * frealloc(ud, NULL, x, s) creates a new block of size 's' (no
32** matter 'x').
33**
34** * frealloc(ud, p, x, 0) frees the block 'p'
35** (in this specific case, frealloc must return NULL);
36** particularly, frealloc(ud, NULL, 0, 0) does nothing
37** (which is equivalent to free(NULL) in ISO C)
38**
39** frealloc returns NULL if it cannot create or reallocate the area
40** (any reallocation to an equal or smaller size cannot fail!)
41*/
42
43
44
45#define MINSIZEARRAY	4
46
47
48void *luaM_growaux_ (lua_State *L, void *block, int *size, size_t size_elems,
49                     int limit, const char *what) {
50  void *newblock;
51  int newsize;
52  if (*size >= limit/2) {  /* cannot double it? */
53    if (*size >= limit)  /* cannot grow even a little? */
54      luaG_runerror(L, "too many %s (limit is %d)", what, limit);
55    newsize = limit;  /* still have at least one free place */
56  }
57  else {
58    newsize = (*size)*2;
59    if (newsize < MINSIZEARRAY)
60      newsize = MINSIZEARRAY;  /* minimum size */
61  }
62  newblock = luaM_reallocv(L, block, *size, newsize, size_elems);
63  *size = newsize;  /* update only when everything else is OK */
64  return newblock;
65}
66
67
68l_noret luaM_toobig (lua_State *L) {
69  luaG_runerror(L, "memory allocation error: block too big");
70}
71
72
73
74/*
75** generic allocation routine.
76*/
77void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
78  void *newblock;
79  global_State *g = G(L);
80  size_t realosize = (block) ? osize : 0;
81  lua_assert((realosize == 0) == (block == NULL));
82#if defined(HARDMEMTESTS)
83  if (nsize > realosize && g->gcrunning)
84    luaC_fullgc(L, 1);  /* force a GC whenever possible */
85#endif
86  newblock = (*g->frealloc)(g->ud, block, osize, nsize);
87  if (newblock == NULL && nsize > 0) {
88    lua_assert(nsize > realosize);  /* cannot fail when shrinking a block */
89    if (g->version) {  /* is state fully built? */
90      luaC_fullgc(L, 1);  /* try to free some memory... */
91      newblock = (*g->frealloc)(g->ud, block, osize, nsize);  /* try again */
92    }
93    if (newblock == NULL)
94      luaD_throw(L, LUA_ERRMEM);
95  }
96  lua_assert((nsize == 0) == (newblock == NULL));
97  g->GCdebt = (g->GCdebt + nsize) - realosize;
98  return newblock;
99}
100
101