1/*
2** State and stack handling.
3** Copyright (C) 2005-2014 Mike Pall. See Copyright Notice in luajit.h
4**
5** Portions taken verbatim or adapted from the Lua interpreter.
6** Copyright (C) 1994-2008 Lua.org, PUC-Rio. See Copyright Notice in lua.h
7*/
8
9#define lj_state_c
10#define LUA_CORE
11
12#include "lj_obj.h"
13#include "lj_gc.h"
14#include "lj_err.h"
15#include "lj_str.h"
16#include "lj_tab.h"
17#include "lj_func.h"
18#include "lj_meta.h"
19#include "lj_state.h"
20#include "lj_frame.h"
21#if LJ_HASFFI
22#include "lj_ctype.h"
23#endif
24#include "lj_trace.h"
25#include "lj_dispatch.h"
26#include "lj_vm.h"
27#include "lj_lex.h"
28#include "lj_alloc.h"
29
30/* -- Stack handling ------------------------------------------------------ */
31
32/* Stack sizes. */
33#define LJ_STACK_MIN LUA_MINSTACK /* Min. stack size. */
34#define LJ_STACK_MAX LUAI_MAXSTACK /* Max. stack size. */
35#define LJ_STACK_START (2*LJ_STACK_MIN) /* Starting stack size. */
36#define LJ_STACK_MAXEX (LJ_STACK_MAX + 1 + LJ_STACK_EXTRA)
37
38/* Explanation of LJ_STACK_EXTRA:
39**
40** Calls to metamethods store their arguments beyond the current top
41** without checking for the stack limit. This avoids stack resizes which
42** would invalidate passed TValue pointers. The stack check is performed
43** later by the function header. This can safely resize the stack or raise
44** an error. Thus we need some extra slots beyond the current stack limit.
45**
46** Most metamethods need 4 slots above top (cont, mobj, arg1, arg2) plus
47** one extra slot if mobj is not a function. Only lj_meta_tset needs 5
48** slots above top, but then mobj is always a function. So we can get by
49** with 5 extra slots.
50*/
51
52/* Resize stack slots and adjust pointers in state. */
53static void resizestack(lua_State *L, MSize n)
54{
55 TValue *st, *oldst = tvref(L->stack);
56 ptrdiff_t delta;
57 MSize oldsize = L->stacksize;
58 MSize realsize = n + 1 + LJ_STACK_EXTRA;
59 GCobj *up;
60 lua_assert((MSize)(tvref(L->maxstack)-oldst)==L->stacksize-LJ_STACK_EXTRA-1);
61 st = (TValue *)lj_mem_realloc(L, tvref(L->stack),
62 (MSize)(L->stacksize*sizeof(TValue)),
63 (MSize)(realsize*sizeof(TValue)));
64 setmref(L->stack, st);
65 delta = (char *)st - (char *)oldst;
66 setmref(L->maxstack, st + n);
67 while (oldsize < realsize) /* Clear new slots. */
68 setnilV(st + oldsize++);
69 L->stacksize = realsize;
70 L->base = (TValue *)((char *)L->base + delta);
71 L->top = (TValue *)((char *)L->top + delta);
72 for (up = gcref(L->openupval); up != NULL; up = gcnext(up))
73 setmref(gco2uv(up)->v, (TValue *)((char *)uvval(gco2uv(up)) + delta));
74 if (obj2gco(L) == gcref(G(L)->jit_L))
75 setmref(G(L)->jit_base, mref(G(L)->jit_base, char) + delta);
76}
77
78/* Relimit stack after error, in case the limit was overdrawn. */
79void lj_state_relimitstack(lua_State *L)
80{
81 if (L->stacksize > LJ_STACK_MAXEX && L->top-tvref(L->stack) < LJ_STACK_MAX-1)
82 resizestack(L, LJ_STACK_MAX);
83}
84
85/* Try to shrink the stack (called from GC). */
86void lj_state_shrinkstack(lua_State *L, MSize used)
87{
88 if (L->stacksize > LJ_STACK_MAXEX)
89 return; /* Avoid stack shrinking while handling stack overflow. */
90 if (4*used < L->stacksize &&
91 2*(LJ_STACK_START+LJ_STACK_EXTRA) < L->stacksize &&
92 obj2gco(L) != gcref(G(L)->jit_L)) /* Don't shrink stack of live trace. */
93 resizestack(L, L->stacksize >> 1);
94}
95
96/* Try to grow stack. */
97void LJ_FASTCALL lj_state_growstack(lua_State *L, MSize need)
98{
99 MSize n;
100 if (L->stacksize > LJ_STACK_MAXEX) /* Overflow while handling overflow? */
101 lj_err_throw(L, LUA_ERRERR);
102 n = L->stacksize + need;
103 if (n > LJ_STACK_MAX) {
104 n += 2*LUA_MINSTACK;
105 } else if (n < 2*L->stacksize) {
106 n = 2*L->stacksize;
107 if (n >= LJ_STACK_MAX)
108 n = LJ_STACK_MAX;
109 }
110 resizestack(L, n);
111 if (L->stacksize > LJ_STACK_MAXEX)
112 lj_err_msg(L, LJ_ERR_STKOV);
113}
114
115void LJ_FASTCALL lj_state_growstack1(lua_State *L)
116{
117 lj_state_growstack(L, 1);
118}
119
120/* Allocate basic stack for new state. */
121static void stack_init(lua_State *L1, lua_State *L)
122{
123 TValue *stend, *st = lj_mem_newvec(L, LJ_STACK_START+LJ_STACK_EXTRA, TValue);
124 setmref(L1->stack, st);
125 L1->stacksize = LJ_STACK_START + LJ_STACK_EXTRA;
126 stend = st + L1->stacksize;
127 setmref(L1->maxstack, stend - LJ_STACK_EXTRA - 1);
128 L1->base = L1->top = st+1;
129 setthreadV(L1, st, L1); /* Needed for curr_funcisL() on empty stack. */
130 while (st < stend) /* Clear new slots. */
131 setnilV(st++);
132}
133
134/* -- State handling ------------------------------------------------------ */
135
136/* Open parts that may cause memory-allocation errors. */
137static TValue *cpluaopen(lua_State *L, lua_CFunction dummy, void *ud)
138{
139 global_State *g = G(L);
140 UNUSED(dummy);
141 UNUSED(ud);
142 stack_init(L, L);
143 /* NOBARRIER: State initialization, all objects are white. */
144 setgcref(L->env, obj2gco(lj_tab_new(L, 0, LJ_MIN_GLOBAL)));
145 settabV(L, registry(L), lj_tab_new(L, 0, LJ_MIN_REGISTRY));
146 lj_str_resize(L, LJ_MIN_STRTAB-1);
147 lj_meta_init(L);
148 lj_lex_init(L);
149 fixstring(lj_err_str(L, LJ_ERR_ERRMEM)); /* Preallocate memory error msg. */
150 g->gc.threshold = 4*g->gc.total;
151 lj_trace_initstate(g);
152 return NULL;
153}
154
155static void close_state(lua_State *L)
156{
157 global_State *g = G(L);
158 lj_func_closeuv(L, tvref(L->stack));
159 lj_gc_freeall(g);
160 lua_assert(gcref(g->gc.root) == obj2gco(L));
161 lua_assert(g->strnum == 0);
162 lj_trace_freestate(g);
163#if LJ_HASFFI
164 lj_ctype_freestate(g);
165#endif
166 lj_mem_freevec(g, g->strhash, g->strmask+1, GCRef);
167 lj_str_freebuf(g, &g->tmpbuf);
168 lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
169 lua_assert(g->gc.total == sizeof(GG_State));
170#ifndef LUAJIT_USE_SYSMALLOC
171 if (g->allocf == lj_alloc_f)
172 lj_alloc_destroy(g->allocd);
173 else
174#endif
175 g->allocf(g->allocd, G2GG(g), sizeof(GG_State), 0);
176}
177
178#if LJ_64
179lua_State *lj_state_newstate(lua_Alloc f, void *ud)
180#else
181LUA_API lua_State *lua_newstate(lua_Alloc f, void *ud)
182#endif
183{
184 GG_State *GG = (GG_State *)f(ud, NULL, 0, sizeof(GG_State));
185 lua_State *L = &GG->L;
186 global_State *g = &GG->g;
187 if (GG == NULL || !checkptr32(GG)) return NULL;
188 memset(GG, 0, sizeof(GG_State));
189 L->gct = ~LJ_TTHREAD;
190 L->marked = LJ_GC_WHITE0 | LJ_GC_FIXED | LJ_GC_SFIXED; /* Prevent free. */
191 L->dummy_ffid = FF_C;
192 setmref(L->glref, g);
193 g->gc.currentwhite = LJ_GC_WHITE0 | LJ_GC_FIXED;
194 g->strempty.marked = LJ_GC_WHITE0;
195 g->strempty.gct = ~LJ_TSTR;
196 g->allocf = f;
197 g->allocd = ud;
198 setgcref(g->mainthref, obj2gco(L));
199 setgcref(g->uvhead.prev, obj2gco(&g->uvhead));
200 setgcref(g->uvhead.next, obj2gco(&g->uvhead));
201 g->strmask = ~(MSize)0;
202 setnilV(registry(L));
203 setnilV(&g->nilnode.val);
204 setnilV(&g->nilnode.key);
205 setmref(g->nilnode.freetop, &g->nilnode);
206 lj_str_initbuf(&g->tmpbuf);
207 g->gc.state = GCSpause;
208 setgcref(g->gc.root, obj2gco(L));
209 setmref(g->gc.sweep, &g->gc.root);
210 g->gc.total = sizeof(GG_State);
211 g->gc.pause = LUAI_GCPAUSE;
212 g->gc.stepmul = LUAI_GCMUL;
213 lj_dispatch_init((GG_State *)L);
214 L->status = LUA_ERRERR+1; /* Avoid touching the stack upon memory error. */
215 if (lj_vm_cpcall(L, NULL, NULL, cpluaopen) != 0) {
216 /* Memory allocation error: free partial state. */
217 close_state(L);
218 return NULL;
219 }
220 L->status = 0;
221 return L;
222}
223
224static TValue *cpfinalize(lua_State *L, lua_CFunction dummy, void *ud)
225{
226 UNUSED(dummy);
227 UNUSED(ud);
228 lj_gc_finalize_cdata(L);
229 lj_gc_finalize_udata(L);
230 /* Frame pop omitted. */
231 return NULL;
232}
233
234LUA_API void lua_close(lua_State *L)
235{
236 global_State *g = G(L);
237 int i;
238 L = mainthread(g); /* Only the main thread can be closed. */
239 lj_func_closeuv(L, tvref(L->stack));
240 lj_gc_separateudata(g, 1); /* Separate udata which have GC metamethods. */
241#if LJ_HASJIT
242 G2J(g)->flags &= ~JIT_F_ON;
243 G2J(g)->state = LJ_TRACE_IDLE;
244 lj_dispatch_update(g);
245#endif
246 for (i = 0;;) {
247 hook_enter(g);
248 L->status = 0;
249 L->cframe = NULL;
250 L->base = L->top = tvref(L->stack) + 1;
251 if (lj_vm_cpcall(L, NULL, NULL, cpfinalize) == 0) {
252 if (++i >= 10) break;
253 lj_gc_separateudata(g, 1); /* Separate udata again. */
254 if (gcref(g->gc.mmudata) == NULL) /* Until nothing is left to do. */
255 break;
256 }
257 }
258 close_state(L);
259}
260
261lua_State *lj_state_new(lua_State *L)
262{
263 lua_State *L1 = lj_mem_newobj(L, lua_State);
264 L1->gct = ~LJ_TTHREAD;
265 L1->dummy_ffid = FF_C;
266 L1->status = 0;
267 L1->stacksize = 0;
268 setmref(L1->stack, NULL);
269 L1->cframe = NULL;
270 /* NOBARRIER: The lua_State is new (marked white). */
271 setgcrefnull(L1->openupval);
272 setmrefr(L1->glref, L->glref);
273 setgcrefr(L1->env, L->env);
274 stack_init(L1, L); /* init stack */
275 lua_assert(iswhite(obj2gco(L1)));
276 return L1;
277}
278
279void LJ_FASTCALL lj_state_free(global_State *g, lua_State *L)
280{
281 lua_assert(L != mainthread(g));
282 lj_func_closeuv(L, tvref(L->stack));
283 lua_assert(gcref(L->openupval) == NULL);
284 lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
285 lj_mem_freet(g, L);
286}
287
288