1 /*
2 ** $Id: lmem.h $
3 ** Interface to Memory Manager
4 ** See Copyright Notice in lua.h
5 */
6 
7 #ifndef lmem_h
8 #define lmem_h
9 
10 
11 #include <stddef.h>
12 
13 #include "llimits.h"
14 #include "lua.h"
15 
16 
17 #define luaM_error(L)	luaD_throw(L, LUA_ERRMEM)
18 
19 
20 /*
21 ** This macro tests whether it is safe to multiply 'n' by the size of
22 ** type 't' without overflows. Because 'e' is always constant, it avoids
23 ** the runtime division MAX_SIZET/(e).
24 ** (The macro is somewhat complex to avoid warnings:  The 'sizeof'
25 ** comparison avoids a runtime comparison when overflow cannot occur.
26 ** The compiler should be able to optimize the real test by itself, but
27 ** when it does it, it may give a warning about "comparison is always
28 ** false due to limited range of data type"; the +1 tricks the compiler,
29 ** avoiding this warning but also this optimization.)
30 */
31 #define luaM_testsize(n,e)  \
32 	(sizeof(n) >= sizeof(size_t) && cast_sizet((n)) + 1 > MAX_SIZET/(e))
33 
34 #define luaM_checksize(L,n,e)  \
35 	(luaM_testsize(n,e) ? luaM_toobig(L) : cast_void(0))
36 
37 
38 /*
39 ** Computes the minimum between 'n' and 'MAX_SIZET/sizeof(t)', so that
40 ** the result is not larger than 'n' and cannot overflow a 'size_t'
41 ** when multiplied by the size of type 't'. (Assumes that 'n' is an
42 ** 'int' or 'unsigned int' and that 'int' is not larger than 'size_t'.)
43 */
44 #define luaM_limitN(n,t)  \
45   ((cast_sizet(n) <= MAX_SIZET/sizeof(t)) ? (n) :  \
46      cast_uint((MAX_SIZET/sizeof(t))))
47 
48 
49 /*
50 ** Arrays of chars do not need any test
51 */
52 #define luaM_reallocvchar(L,b,on,n)  \
53   cast_charp(luaM_saferealloc_(L, (b), (on)*sizeof(char), (n)*sizeof(char)))
54 
55 #define luaM_freemem(L, b, s)	luaM_free_(L, (b), (s))
56 #define luaM_free(L, b)		luaM_free_(L, (b), sizeof(*(b)))
57 #define luaM_freearray(L, b, n)   luaM_free_(L, (b), (n)*sizeof(*(b)))
58 
59 #define luaM_new(L,t)		cast(t*, luaM_malloc_(L, sizeof(t), 0))
60 #define luaM_newvector(L,n,t)	cast(t*, luaM_malloc_(L, (n)*sizeof(t), 0))
61 #define luaM_newvectorchecked(L,n,t) \
62   (luaM_checksize(L,n,sizeof(t)), luaM_newvector(L,n,t))
63 
64 #define luaM_newobject(L,tag,s)	luaM_malloc_(L, (s), tag)
65 
66 #define luaM_growvector(L,v,nelems,size,t,limit,e) \
67 	((v)=cast(t *, luaM_growaux_(L,v,nelems,&(size),sizeof(t), \
68                          luaM_limitN(limit,t),e)))
69 
70 #define luaM_reallocvector(L, v,oldn,n,t) \
71    (cast(t *, luaM_realloc_(L, v, cast_sizet(oldn) * sizeof(t), \
72                                   cast_sizet(n) * sizeof(t))))
73 
74 #define luaM_shrinkvector(L,v,size,fs,t) \
75    ((v)=cast(t *, luaM_shrinkvector_(L, v, &(size), fs, sizeof(t))))
76 
77 LUAI_FUNC l_noret luaM_toobig (lua_State *L);
78 
79 /* not to be called directly */
80 LUAI_FUNC void *luaM_realloc_ (lua_State *L, void *block, size_t oldsize,
81                                                           size_t size);
82 LUAI_FUNC void *luaM_saferealloc_ (lua_State *L, void *block, size_t oldsize,
83                                                               size_t size);
84 LUAI_FUNC void luaM_free_ (lua_State *L, void *block, size_t osize);
85 LUAI_FUNC void *luaM_growaux_ (lua_State *L, void *block, int nelems,
86                                int *size, int size_elem, int limit,
87                                const char *what);
88 LUAI_FUNC void *luaM_shrinkvector_ (lua_State *L, void *block, int *nelem,
89                                     int final_n, int size_elem);
90 LUAI_FUNC void *luaM_malloc_ (lua_State *L, size_t size, int tag);
91 
92 #endif
93 
94