Line | Branch | Decision | Exec | Source |
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1 | /* | |||
2 | ** $Id: lmem.c $ | |||
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, p, x, 0) frees the block 'p' and returns NULL. | |||
32 | ** Particularly, frealloc(ud, NULL, 0, 0) does nothing, | |||
33 | ** which is equivalent to free(NULL) in ISO C. | |||
34 | ** | |||
35 | ** - frealloc(ud, NULL, x, s) creates a new block of size 's' | |||
36 | ** (no matter 'x'). Returns NULL if it cannot create the new block. | |||
37 | ** | |||
38 | ** - otherwise, frealloc(ud, b, x, y) reallocates the block 'b' from | |||
39 | ** size 'x' to size 'y'. Returns NULL if it cannot reallocate the | |||
40 | ** block to the new size. | |||
41 | */ | |||
42 | ||||
43 | ||||
44 | /* | |||
45 | ** Macro to call the allocation function. | |||
46 | */ | |||
47 | #define callfrealloc(g,block,os,ns) ((*g->frealloc)(g->ud, block, os, ns)) | |||
48 | ||||
49 | ||||
50 | /* | |||
51 | ** When an allocation fails, it will try again after an emergency | |||
52 | ** collection, except when it cannot run a collection. The GC should | |||
53 | ** not be called while the state is not fully built, as the collector | |||
54 | ** is not yet fully initialized. Also, it should not be called when | |||
55 | ** 'gcstopem' is true, because then the interpreter is in the middle of | |||
56 | ** a collection step. | |||
57 | */ | |||
58 | #define cantryagain(g) (completestate(g) && !g->gcstopem) | |||
59 | ||||
60 | ||||
61 | ||||
62 | ||||
63 | #if defined(EMERGENCYGCTESTS) | |||
64 | /* | |||
65 | ** First allocation will fail except when freeing a block (frees never | |||
66 | ** fail) and when it cannot try again; this fail will trigger 'tryagain' | |||
67 | ** and a full GC cycle at every allocation. | |||
68 | */ | |||
69 | static void *firsttry (global_State *g, void *block, size_t os, size_t ns) { | |||
70 | if (ns > 0 && cantryagain(g)) | |||
71 | return NULL; /* fail */ | |||
72 | else /* normal allocation */ | |||
73 | return callfrealloc(g, block, os, ns); | |||
74 | } | |||
75 | #else | |||
76 | #define firsttry(g,block,os,ns) callfrealloc(g, block, os, ns) | |||
77 | #endif | |||
78 | ||||
79 | ||||
80 | ||||
81 | ||||
82 | ||||
83 | /* | |||
84 | ** {================================================================== | |||
85 | ** Functions to allocate/deallocate arrays for the Parser | |||
86 | ** =================================================================== | |||
87 | */ | |||
88 | ||||
89 | /* | |||
90 | ** Minimum size for arrays during parsing, to avoid overhead of | |||
91 | ** reallocating to size 1, then 2, and then 4. All these arrays | |||
92 | ** will be reallocated to exact sizes or erased when parsing ends. | |||
93 | */ | |||
94 | #define MINSIZEARRAY 4 | |||
95 | ||||
96 | ||||
97 | 20917 | void *luaM_growaux_ (lua_State *L, void *block, int nelems, int *psize, | ||
98 | int size_elems, int limit, const char *what) { | |||
99 | void *newblock; | |||
100 | 20917 | int size = *psize; | ||
101 |
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20917 | if (nelems + 1 <= size) /* does one extra element still fit? */ |
102 | 16464 | return block; /* nothing to be done */ | ||
103 |
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4453 | if (size >= limit / 2) { /* cannot double it? */ |
104 | ✗ | if (l_unlikely(size >= limit)) /* cannot grow even a little? */ | ||
105 | ✗ | luaG_runerror(L, "too many %s (limit is %d)", what, limit); | ||
106 | ✗ | size = limit; /* still have at least one free place */ | ||
107 | } | |||
108 | else { | |||
109 | 4453 | size *= 2; | ||
110 |
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4453 | if (size < MINSIZEARRAY) |
111 | 2339 | size = MINSIZEARRAY; /* minimum size */ | ||
112 | } | |||
113 | lua_assert(nelems + 1 <= size && size <= limit); | |||
114 | /* 'limit' ensures that multiplication will not overflow */ | |||
115 | 4453 | newblock = luaM_saferealloc_(L, block, cast_sizet(*psize) * size_elems, | ||
116 | 4453 | cast_sizet(size) * size_elems); | ||
117 | 4453 | *psize = size; /* update only when everything else is OK */ | ||
118 | 4453 | return newblock; | ||
119 | } | |||
120 | ||||
121 | ||||
122 | /* | |||
123 | ** In prototypes, the size of the array is also its number of | |||
124 | ** elements (to save memory). So, if it cannot shrink an array | |||
125 | ** to its number of elements, the only option is to raise an | |||
126 | ** error. | |||
127 | */ | |||
128 | 3661 | void *luaM_shrinkvector_ (lua_State *L, void *block, int *size, | ||
129 | int final_n, int size_elem) { | |||
130 | void *newblock; | |||
131 | 3661 | size_t oldsize = cast_sizet((*size) * size_elem); | ||
132 | 3661 | size_t newsize = cast_sizet(final_n * size_elem); | ||
133 | lua_assert(newsize <= oldsize); | |||
134 | 3661 | newblock = luaM_saferealloc_(L, block, oldsize, newsize); | ||
135 | 3661 | *size = final_n; | ||
136 | 3661 | return newblock; | ||
137 | } | |||
138 | ||||
139 | /* }================================================================== */ | |||
140 | ||||
141 | ||||
142 | ✗ | l_noret luaM_toobig (lua_State *L) { | ||
143 | ✗ | luaG_runerror(L, "memory allocation error: block too big"); | ||
144 | } | |||
145 | ||||
146 | ||||
147 | /* | |||
148 | ** Free memory | |||
149 | */ | |||
150 | 101362 | void luaM_free_ (lua_State *L, void *block, size_t osize) { | ||
151 | 101362 | global_State *g = G(L); | ||
152 | lua_assert((osize == 0) == (block == NULL)); | |||
153 | 101362 | callfrealloc(g, block, osize, 0); | ||
154 | 101362 | g->GCdebt -= osize; | ||
155 | 101362 | } | ||
156 | ||||
157 | ||||
158 | /* | |||
159 | ** In case of allocation fail, this function will do an emergency | |||
160 | ** collection to free some memory and then try the allocation again. | |||
161 | */ | |||
162 | ✗ | static void *tryagain (lua_State *L, void *block, | ||
163 | size_t osize, size_t nsize) { | |||
164 | ✗ | global_State *g = G(L); | ||
165 | ✗ | if (cantryagain(g)) { | ||
166 | ✗ | luaC_fullgc(L, 1); /* try to free some memory... */ | ||
167 | ✗ | return callfrealloc(g, block, osize, nsize); /* try again */ | ||
168 | } | |||
169 | ✗ | else return NULL; /* cannot run an emergency collection */ | ||
170 | } | |||
171 | ||||
172 | ||||
173 | /* | |||
174 | ** Generic allocation routine. | |||
175 | */ | |||
176 | 24055 | void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) { | ||
177 | void *newblock; | |||
178 | 24055 | global_State *g = G(L); | ||
179 | lua_assert((osize == 0) == (block == NULL)); | |||
180 | 24055 | newblock = firsttry(g, block, osize, nsize); | ||
181 |
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24055 | if (l_unlikely(newblock == NULL && nsize > 0)) { |
182 | ✗ | newblock = tryagain(L, block, osize, nsize); | ||
183 | ✗ | if (newblock == NULL) /* still no memory? */ | ||
184 | ✗ | return NULL; /* do not update 'GCdebt' */ | ||
185 | } | |||
186 | lua_assert((nsize == 0) == (newblock == NULL)); | |||
187 | 24055 | g->GCdebt = (g->GCdebt + nsize) - osize; | ||
188 | 24055 | return newblock; | ||
189 | } | |||
190 | ||||
191 | ||||
192 | 8732 | void *luaM_saferealloc_ (lua_State *L, void *block, size_t osize, | ||
193 | size_t nsize) { | |||
194 | 8732 | void *newblock = luaM_realloc_(L, block, osize, nsize); | ||
195 |
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8732 | if (l_unlikely(newblock == NULL && nsize > 0)) /* allocation failed? */ |
196 | ✗ | luaM_error(L); | ||
197 | 8732 | return newblock; | ||
198 | } | |||
199 | ||||
200 | ||||
201 | 89554 | void *luaM_malloc_ (lua_State *L, size_t size, int tag) { | ||
202 |
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89554 | if (size == 0) |
203 | ✗ | return NULL; /* that's all */ | ||
204 | else { | |||
205 | 89554 | global_State *g = G(L); | ||
206 | 89554 | void *newblock = firsttry(g, NULL, tag, size); | ||
207 |
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89554 | if (l_unlikely(newblock == NULL)) { |
208 | ✗ | newblock = tryagain(L, NULL, tag, size); | ||
209 | ✗ | if (newblock == NULL) | ||
210 | ✗ | luaM_error(L); | ||
211 | } | |||
212 | 89554 | g->GCdebt += size; | ||
213 | 89554 | return newblock; | ||
214 | } | |||
215 | } | |||
216 |