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 
luaM_growaux_(lua_State * L,void * block,int * size,size_t size_elems,int limit,const char * what)48 void *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 
luaM_toobig(lua_State * L)68 l_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 */
luaM_realloc_(lua_State * L,void * block,size_t osize,size_t nsize)77 void *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