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