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d99a0153 CW |
1 | /* |
2 | ** $Id: ldo.c,v 2.108.1.3 2013/11/08 18:22:50 roberto Exp $ | |
3 | ** Stack and Call structure of Lua | |
4 | ** See Copyright Notice in lua.h | |
5 | */ | |
6 | ||
7 | ||
8 | #define ldo_c | |
9 | #define LUA_CORE | |
10 | ||
11 | #include <sys/lua/lua.h> | |
12 | ||
13 | #include "lapi.h" | |
14 | #include "ldebug.h" | |
15 | #include "ldo.h" | |
16 | #include "lfunc.h" | |
17 | #include "lgc.h" | |
18 | #include "lmem.h" | |
19 | #include "lobject.h" | |
20 | #include "lopcodes.h" | |
21 | #include "lparser.h" | |
22 | #include "lstate.h" | |
23 | #include "lstring.h" | |
24 | #include "ltable.h" | |
25 | #include "ltm.h" | |
d99a0153 CW |
26 | #include "lvm.h" |
27 | #include "lzio.h" | |
28 | ||
29 | ||
30 | ||
3eabed74 MA |
31 | /* Return the number of bytes available on the stack. */ |
32 | #if defined (_KERNEL) && defined(__linux__) | |
33 | #include <asm/current.h> | |
34 | static intptr_t stack_remaining(void) { | |
d8a09b3a RL |
35 | intptr_t local; |
36 | local = (intptr_t)&local - (intptr_t)current->stack; | |
37 | return local; | |
3eabed74 MA |
38 | } |
39 | #elif defined (_KERNEL) && defined(__FreeBSD__) | |
40 | #include <sys/pcpu.h> | |
41 | static intptr_t stack_remaining(void) { | |
d8a09b3a RL |
42 | intptr_t local; |
43 | local = (intptr_t)&local - (intptr_t)curthread->td_kstack; | |
44 | return local; | |
3eabed74 MA |
45 | } |
46 | #else | |
47 | static intptr_t stack_remaining(void) { | |
48 | return INTPTR_MAX; | |
49 | } | |
50 | #endif | |
d99a0153 CW |
51 | |
52 | /* | |
53 | ** {====================================================== | |
54 | ** Error-recovery functions | |
55 | ** ======================================================= | |
56 | */ | |
57 | ||
58 | /* | |
59 | ** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By | |
60 | ** default, Lua handles errors with exceptions when compiling as | |
61 | ** C++ code, with _longjmp/_setjmp when asked to use them, and with | |
62 | ** longjmp/setjmp otherwise. | |
63 | */ | |
64 | #if !defined(LUAI_THROW) | |
65 | ||
66 | #ifdef _KERNEL | |
67 | ||
cf2eba66 | 68 | #ifdef __linux__ |
d99a0153 CW |
69 | #if defined(__i386__) |
70 | #define JMP_BUF_CNT 6 | |
71 | #elif defined(__x86_64__) | |
72 | #define JMP_BUF_CNT 8 | |
73 | #elif defined(__sparc__) && defined(__arch64__) | |
74 | #define JMP_BUF_CNT 6 | |
75 | #elif defined(__powerpc__) | |
76 | #define JMP_BUF_CNT 26 | |
77 | #elif defined(__aarch64__) | |
78 | #define JMP_BUF_CNT 64 | |
79 | #elif defined(__arm__) | |
80 | #define JMP_BUF_CNT 65 | |
81 | #elif defined(__mips__) | |
82 | #define JMP_BUF_CNT 12 | |
83 | #elif defined(__s390x__) | |
adf495e2 | 84 | #define JMP_BUF_CNT 18 |
4254e407 RD |
85 | #elif defined(__riscv) |
86 | #define JMP_BUF_CNT 64 | |
d99a0153 CW |
87 | #else |
88 | #define JMP_BUF_CNT 1 | |
89 | #endif | |
90 | ||
91 | typedef struct _label_t { long long unsigned val[JMP_BUF_CNT]; } label_t; | |
92 | ||
93 | int setjmp(label_t *) __attribute__ ((__nothrow__)); | |
460748d4 | 94 | extern __attribute__((noreturn)) void longjmp(label_t *); |
d99a0153 CW |
95 | |
96 | #define LUAI_THROW(L,c) longjmp(&(c)->b) | |
97 | #define LUAI_TRY(L,c,a) if (setjmp(&(c)->b) == 0) { a } | |
98 | #define luai_jmpbuf label_t | |
99 | ||
dd4bc569 | 100 | /* unsupported arches will build but not be able to run lua programs */ |
d99a0153 CW |
101 | #if JMP_BUF_CNT == 1 |
102 | int setjmp (label_t *buf) { | |
103 | return 1; | |
104 | } | |
105 | ||
106 | void longjmp (label_t * buf) { | |
107 | for (;;); | |
108 | } | |
109 | #endif | |
cf2eba66 MM |
110 | #else |
111 | #define LUAI_THROW(L,c) longjmp((c)->b, 1) | |
112 | #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a } | |
113 | #define luai_jmpbuf jmp_buf | |
114 | #endif | |
d99a0153 CW |
115 | |
116 | #else /* _KERNEL */ | |
117 | ||
118 | #if defined(__cplusplus) && !defined(LUA_USE_LONGJMP) | |
119 | /* C++ exceptions */ | |
120 | #define LUAI_THROW(L,c) throw(c) | |
121 | #define LUAI_TRY(L,c,a) \ | |
122 | try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; } | |
123 | #define luai_jmpbuf int /* dummy variable */ | |
124 | ||
125 | #elif defined(LUA_USE_ULONGJMP) | |
126 | /* in Unix, try _longjmp/_setjmp (more efficient) */ | |
127 | #define LUAI_THROW(L,c) _longjmp((c)->b, 1) | |
128 | #define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a } | |
129 | #define luai_jmpbuf jmp_buf | |
130 | ||
131 | #else | |
132 | /* default handling with long jumps */ | |
133 | #define LUAI_THROW(L,c) longjmp((c)->b, 1) | |
134 | #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a } | |
135 | #define luai_jmpbuf jmp_buf | |
136 | ||
137 | #endif | |
138 | ||
139 | #endif /* _KERNEL */ | |
140 | ||
141 | #endif /* LUAI_THROW */ | |
142 | ||
143 | ||
144 | /* chain list of long jump buffers */ | |
145 | struct lua_longjmp { | |
146 | struct lua_longjmp *previous; | |
147 | luai_jmpbuf b; | |
148 | volatile int status; /* error code */ | |
149 | }; | |
150 | ||
151 | ||
152 | static void seterrorobj (lua_State *L, int errcode, StkId oldtop) { | |
153 | switch (errcode) { | |
154 | case LUA_ERRMEM: { /* memory error? */ | |
155 | setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */ | |
156 | break; | |
157 | } | |
158 | case LUA_ERRERR: { | |
159 | setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling")); | |
160 | break; | |
161 | } | |
162 | default: { | |
163 | setobjs2s(L, oldtop, L->top - 1); /* error message on current top */ | |
164 | break; | |
165 | } | |
166 | } | |
167 | L->top = oldtop + 1; | |
168 | } | |
169 | ||
170 | ||
171 | l_noret luaD_throw (lua_State *L, int errcode) { | |
172 | if (L->errorJmp) { /* thread has an error handler? */ | |
173 | L->errorJmp->status = errcode; /* set status */ | |
174 | LUAI_THROW(L, L->errorJmp); /* jump to it */ | |
175 | } | |
176 | else { /* thread has no error handler */ | |
177 | L->status = cast_byte(errcode); /* mark it as dead */ | |
178 | if (G(L)->mainthread->errorJmp) { /* main thread has a handler? */ | |
179 | setobjs2s(L, G(L)->mainthread->top++, L->top - 1); /* copy error obj. */ | |
180 | luaD_throw(G(L)->mainthread, errcode); /* re-throw in main thread */ | |
181 | } | |
182 | else { /* no handler at all; abort */ | |
183 | if (G(L)->panic) { /* panic function? */ | |
184 | lua_unlock(L); | |
185 | G(L)->panic(L); /* call it (last chance to jump out) */ | |
186 | } | |
187 | panic("no error handler"); | |
188 | } | |
189 | } | |
190 | } | |
191 | ||
192 | ||
193 | int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) { | |
194 | unsigned short oldnCcalls = L->nCcalls; | |
195 | struct lua_longjmp lj; | |
196 | lj.status = LUA_OK; | |
197 | lj.previous = L->errorJmp; /* chain new error handler */ | |
198 | L->errorJmp = &lj; | |
199 | LUAI_TRY(L, &lj, | |
200 | (*f)(L, ud); | |
201 | ); | |
202 | L->errorJmp = lj.previous; /* restore old error handler */ | |
203 | L->nCcalls = oldnCcalls; | |
204 | return lj.status; | |
205 | } | |
206 | ||
207 | /* }====================================================== */ | |
208 | ||
209 | ||
210 | static void correctstack (lua_State *L, TValue *oldstack) { | |
211 | CallInfo *ci; | |
212 | GCObject *up; | |
213 | L->top = (L->top - oldstack) + L->stack; | |
214 | for (up = L->openupval; up != NULL; up = up->gch.next) | |
215 | gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack; | |
216 | for (ci = L->ci; ci != NULL; ci = ci->previous) { | |
217 | ci->top = (ci->top - oldstack) + L->stack; | |
218 | ci->func = (ci->func - oldstack) + L->stack; | |
219 | if (isLua(ci)) | |
220 | ci->u.l.base = (ci->u.l.base - oldstack) + L->stack; | |
221 | } | |
222 | } | |
223 | ||
224 | ||
225 | /* some space for error handling */ | |
226 | #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200) | |
227 | ||
228 | ||
229 | void luaD_reallocstack (lua_State *L, int newsize) { | |
230 | TValue *oldstack = L->stack; | |
231 | int lim = L->stacksize; | |
232 | lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE); | |
233 | lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK); | |
234 | luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue); | |
235 | for (; lim < newsize; lim++) | |
236 | setnilvalue(L->stack + lim); /* erase new segment */ | |
237 | L->stacksize = newsize; | |
238 | L->stack_last = L->stack + newsize - EXTRA_STACK; | |
239 | correctstack(L, oldstack); | |
240 | } | |
241 | ||
242 | ||
243 | void luaD_growstack (lua_State *L, int n) { | |
244 | int size = L->stacksize; | |
245 | if (size > LUAI_MAXSTACK) /* error after extra size? */ | |
246 | luaD_throw(L, LUA_ERRERR); | |
247 | else { | |
248 | int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK; | |
249 | int newsize = 2 * size; | |
250 | if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK; | |
251 | if (newsize < needed) newsize = needed; | |
252 | if (newsize > LUAI_MAXSTACK) { /* stack overflow? */ | |
253 | luaD_reallocstack(L, ERRORSTACKSIZE); | |
254 | luaG_runerror(L, "stack overflow"); | |
255 | } | |
256 | else | |
257 | luaD_reallocstack(L, newsize); | |
258 | } | |
259 | } | |
260 | ||
261 | ||
262 | static int stackinuse (lua_State *L) { | |
263 | CallInfo *ci; | |
264 | StkId lim = L->top; | |
265 | for (ci = L->ci; ci != NULL; ci = ci->previous) { | |
266 | lua_assert(ci->top <= L->stack_last); | |
267 | if (lim < ci->top) lim = ci->top; | |
268 | } | |
269 | return cast_int(lim - L->stack) + 1; /* part of stack in use */ | |
270 | } | |
271 | ||
272 | ||
273 | void luaD_shrinkstack (lua_State *L) { | |
274 | int inuse = stackinuse(L); | |
275 | int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK; | |
276 | if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK; | |
277 | if (inuse > LUAI_MAXSTACK || /* handling stack overflow? */ | |
278 | goodsize >= L->stacksize) /* would grow instead of shrink? */ | |
279 | condmovestack(L); /* don't change stack (change only for debugging) */ | |
280 | else | |
281 | luaD_reallocstack(L, goodsize); /* shrink it */ | |
282 | } | |
283 | ||
284 | ||
285 | void luaD_hook (lua_State *L, int event, int line) { | |
286 | lua_Hook hook = L->hook; | |
287 | if (hook && L->allowhook) { | |
288 | CallInfo *ci = L->ci; | |
289 | ptrdiff_t top = savestack(L, L->top); | |
290 | ptrdiff_t ci_top = savestack(L, ci->top); | |
291 | lua_Debug ar; | |
292 | ar.event = event; | |
293 | ar.currentline = line; | |
294 | ar.i_ci = ci; | |
295 | luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */ | |
296 | ci->top = L->top + LUA_MINSTACK; | |
297 | lua_assert(ci->top <= L->stack_last); | |
298 | L->allowhook = 0; /* cannot call hooks inside a hook */ | |
299 | ci->callstatus |= CIST_HOOKED; | |
300 | lua_unlock(L); | |
301 | (*hook)(L, &ar); | |
302 | lua_lock(L); | |
303 | lua_assert(!L->allowhook); | |
304 | L->allowhook = 1; | |
305 | ci->top = restorestack(L, ci_top); | |
306 | L->top = restorestack(L, top); | |
307 | ci->callstatus &= ~CIST_HOOKED; | |
308 | } | |
309 | } | |
310 | ||
311 | ||
312 | static void callhook (lua_State *L, CallInfo *ci) { | |
313 | int hook = LUA_HOOKCALL; | |
314 | ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */ | |
315 | if (isLua(ci->previous) && | |
316 | GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) { | |
317 | ci->callstatus |= CIST_TAIL; | |
318 | hook = LUA_HOOKTAILCALL; | |
319 | } | |
320 | luaD_hook(L, hook, -1); | |
321 | ci->u.l.savedpc--; /* correct 'pc' */ | |
322 | } | |
323 | ||
324 | ||
325 | static StkId adjust_varargs (lua_State *L, Proto *p, int actual) { | |
326 | int i; | |
327 | int nfixargs = p->numparams; | |
328 | StkId base, fixed; | |
329 | lua_assert(actual >= nfixargs); | |
330 | /* move fixed parameters to final position */ | |
331 | luaD_checkstack(L, p->maxstacksize); /* check again for new 'base' */ | |
332 | fixed = L->top - actual; /* first fixed argument */ | |
333 | base = L->top; /* final position of first argument */ | |
334 | for (i=0; i<nfixargs; i++) { | |
335 | setobjs2s(L, L->top++, fixed + i); | |
336 | setnilvalue(fixed + i); | |
337 | } | |
338 | return base; | |
339 | } | |
340 | ||
341 | ||
342 | static StkId tryfuncTM (lua_State *L, StkId func) { | |
343 | const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL); | |
344 | StkId p; | |
345 | ptrdiff_t funcr = savestack(L, func); | |
346 | if (!ttisfunction(tm)) | |
347 | luaG_typeerror(L, func, "call"); | |
348 | /* Open a hole inside the stack at `func' */ | |
349 | for (p = L->top; p > func; p--) setobjs2s(L, p, p-1); | |
350 | incr_top(L); | |
351 | func = restorestack(L, funcr); /* previous call may change stack */ | |
352 | setobj2s(L, func, tm); /* tag method is the new function to be called */ | |
353 | return func; | |
354 | } | |
355 | ||
356 | ||
357 | ||
358 | #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L))) | |
359 | ||
360 | ||
361 | /* | |
362 | ** returns true if function has been executed (C function) | |
363 | */ | |
364 | int luaD_precall (lua_State *L, StkId func, int nresults) { | |
365 | lua_CFunction f; | |
366 | CallInfo *ci; | |
367 | int n; /* number of arguments (Lua) or returns (C) */ | |
368 | ptrdiff_t funcr = savestack(L, func); | |
369 | switch (ttype(func)) { | |
370 | case LUA_TLCF: /* light C function */ | |
371 | f = fvalue(func); | |
372 | goto Cfunc; | |
373 | case LUA_TCCL: { /* C closure */ | |
374 | f = clCvalue(func)->f; | |
375 | Cfunc: | |
376 | luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */ | |
377 | ci = next_ci(L); /* now 'enter' new function */ | |
378 | ci->nresults = nresults; | |
379 | ci->func = restorestack(L, funcr); | |
380 | ci->top = L->top + LUA_MINSTACK; | |
381 | lua_assert(ci->top <= L->stack_last); | |
382 | ci->callstatus = 0; | |
383 | luaC_checkGC(L); /* stack grow uses memory */ | |
384 | if (L->hookmask & LUA_MASKCALL) | |
385 | luaD_hook(L, LUA_HOOKCALL, -1); | |
386 | lua_unlock(L); | |
387 | n = (*f)(L); /* do the actual call */ | |
388 | lua_lock(L); | |
389 | api_checknelems(L, n); | |
390 | luaD_poscall(L, L->top - n); | |
391 | return 1; | |
392 | } | |
393 | case LUA_TLCL: { /* Lua function: prepare its call */ | |
394 | StkId base; | |
395 | Proto *p = clLvalue(func)->p; | |
396 | n = cast_int(L->top - func) - 1; /* number of real arguments */ | |
397 | luaD_checkstack(L, p->maxstacksize); | |
398 | for (; n < p->numparams; n++) | |
399 | setnilvalue(L->top++); /* complete missing arguments */ | |
400 | if (!p->is_vararg) { | |
401 | func = restorestack(L, funcr); | |
402 | base = func + 1; | |
403 | } | |
404 | else { | |
405 | base = adjust_varargs(L, p, n); | |
406 | func = restorestack(L, funcr); /* previous call can change stack */ | |
407 | } | |
408 | ci = next_ci(L); /* now 'enter' new function */ | |
409 | ci->nresults = nresults; | |
410 | ci->func = func; | |
411 | ci->u.l.base = base; | |
412 | ci->top = base + p->maxstacksize; | |
413 | lua_assert(ci->top <= L->stack_last); | |
414 | ci->u.l.savedpc = p->code; /* starting point */ | |
415 | ci->callstatus = CIST_LUA; | |
416 | L->top = ci->top; | |
417 | luaC_checkGC(L); /* stack grow uses memory */ | |
418 | if (L->hookmask & LUA_MASKCALL) | |
419 | callhook(L, ci); | |
420 | return 0; | |
421 | } | |
422 | default: { /* not a function */ | |
423 | func = tryfuncTM(L, func); /* retry with 'function' tag method */ | |
424 | return luaD_precall(L, func, nresults); /* now it must be a function */ | |
425 | } | |
426 | } | |
427 | } | |
428 | ||
429 | ||
430 | int luaD_poscall (lua_State *L, StkId firstResult) { | |
431 | StkId res; | |
432 | int wanted, i; | |
433 | CallInfo *ci = L->ci; | |
434 | if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) { | |
435 | if (L->hookmask & LUA_MASKRET) { | |
436 | ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */ | |
437 | luaD_hook(L, LUA_HOOKRET, -1); | |
438 | firstResult = restorestack(L, fr); | |
439 | } | |
440 | L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */ | |
441 | } | |
442 | res = ci->func; /* res == final position of 1st result */ | |
443 | wanted = ci->nresults; | |
444 | L->ci = ci = ci->previous; /* back to caller */ | |
445 | /* move results to correct place */ | |
446 | for (i = wanted; i != 0 && firstResult < L->top; i--) | |
447 | setobjs2s(L, res++, firstResult++); | |
448 | while (i-- > 0) | |
449 | setnilvalue(res++); | |
450 | L->top = res; | |
451 | return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */ | |
452 | } | |
453 | ||
454 | ||
455 | /* | |
456 | ** Call a function (C or Lua). The function to be called is at *func. | |
457 | ** The arguments are on the stack, right after the function. | |
458 | ** When returns, all the results are on the stack, starting at the original | |
459 | ** function position. | |
460 | */ | |
461 | void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) { | |
462 | if (++L->nCcalls >= LUAI_MAXCCALLS) { | |
463 | if (L->nCcalls == LUAI_MAXCCALLS) | |
464 | luaG_runerror(L, "C stack overflow"); | |
465 | else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3))) | |
3eabed74 | 466 | luaD_throw(L, LUA_ERRERR); /* error while handling stack error */ |
d99a0153 | 467 | } |
3eabed74 MA |
468 | intptr_t remaining = stack_remaining(); |
469 | if (L->runerror == 0 && remaining < LUAI_MINCSTACK) | |
470 | luaG_runerror(L, "C stack overflow"); | |
471 | if (L->runerror != 0 && remaining < LUAI_MINCSTACK / 2) | |
472 | luaD_throw(L, LUA_ERRERR); /* error while handling stack error */ | |
d99a0153 CW |
473 | if (!allowyield) L->nny++; |
474 | if (!luaD_precall(L, func, nResults)) /* is a Lua function? */ | |
475 | luaV_execute(L); /* call it */ | |
476 | if (!allowyield) L->nny--; | |
477 | L->nCcalls--; | |
478 | } | |
479 | ||
480 | ||
481 | static void finishCcall (lua_State *L) { | |
482 | CallInfo *ci = L->ci; | |
483 | int n; | |
484 | lua_assert(ci->u.c.k != NULL); /* must have a continuation */ | |
485 | lua_assert(L->nny == 0); | |
486 | if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */ | |
487 | ci->callstatus &= ~CIST_YPCALL; /* finish 'lua_pcall' */ | |
488 | L->errfunc = ci->u.c.old_errfunc; | |
489 | } | |
490 | /* finish 'lua_callk'/'lua_pcall' */ | |
491 | adjustresults(L, ci->nresults); | |
492 | /* call continuation function */ | |
493 | if (!(ci->callstatus & CIST_STAT)) /* no call status? */ | |
494 | ci->u.c.status = LUA_YIELD; /* 'default' status */ | |
495 | lua_assert(ci->u.c.status != LUA_OK); | |
496 | ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED; | |
497 | lua_unlock(L); | |
498 | n = (*ci->u.c.k)(L); | |
499 | lua_lock(L); | |
500 | api_checknelems(L, n); | |
501 | /* finish 'luaD_precall' */ | |
502 | luaD_poscall(L, L->top - n); | |
503 | } | |
504 | ||
505 | ||
506 | static void unroll (lua_State *L, void *ud) { | |
507 | UNUSED(ud); | |
508 | for (;;) { | |
509 | if (L->ci == &L->base_ci) /* stack is empty? */ | |
510 | return; /* coroutine finished normally */ | |
511 | if (!isLua(L->ci)) /* C function? */ | |
512 | finishCcall(L); | |
513 | else { /* Lua function */ | |
514 | luaV_finishOp(L); /* finish interrupted instruction */ | |
515 | luaV_execute(L); /* execute down to higher C 'boundary' */ | |
516 | } | |
517 | } | |
518 | } | |
519 | ||
520 | ||
521 | /* | |
522 | ** check whether thread has a suspended protected call | |
523 | */ | |
524 | static CallInfo *findpcall (lua_State *L) { | |
525 | CallInfo *ci; | |
526 | for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */ | |
527 | if (ci->callstatus & CIST_YPCALL) | |
528 | return ci; | |
529 | } | |
530 | return NULL; /* no pending pcall */ | |
531 | } | |
532 | ||
533 | ||
534 | static int recover (lua_State *L, int status) { | |
535 | StkId oldtop; | |
536 | CallInfo *ci = findpcall(L); | |
537 | if (ci == NULL) return 0; /* no recovery point */ | |
538 | /* "finish" luaD_pcall */ | |
539 | oldtop = restorestack(L, ci->extra); | |
540 | luaF_close(L, oldtop); | |
541 | seterrorobj(L, status, oldtop); | |
542 | L->ci = ci; | |
543 | L->allowhook = ci->u.c.old_allowhook; | |
544 | L->nny = 0; /* should be zero to be yieldable */ | |
545 | luaD_shrinkstack(L); | |
546 | L->errfunc = ci->u.c.old_errfunc; | |
547 | ci->callstatus |= CIST_STAT; /* call has error status */ | |
548 | ci->u.c.status = status; /* (here it is) */ | |
549 | return 1; /* continue running the coroutine */ | |
550 | } | |
551 | ||
552 | ||
553 | /* | |
554 | ** signal an error in the call to 'resume', not in the execution of the | |
555 | ** coroutine itself. (Such errors should not be handled by any coroutine | |
556 | ** error handler and should not kill the coroutine.) | |
557 | */ | |
558 | static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) { | |
559 | L->top = firstArg; /* remove args from the stack */ | |
560 | setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */ | |
561 | api_incr_top(L); | |
562 | luaD_throw(L, -1); /* jump back to 'lua_resume' */ | |
563 | } | |
564 | ||
565 | ||
566 | /* | |
567 | ** do the work for 'lua_resume' in protected mode | |
568 | */ | |
569 | static void resume_cb (lua_State *L, void *ud) { | |
570 | int nCcalls = L->nCcalls; | |
571 | StkId firstArg = cast(StkId, ud); | |
572 | CallInfo *ci = L->ci; | |
573 | if (nCcalls >= LUAI_MAXCCALLS) | |
574 | resume_error(L, "C stack overflow", firstArg); | |
575 | if (L->status == LUA_OK) { /* may be starting a coroutine */ | |
576 | if (ci != &L->base_ci) /* not in base level? */ | |
577 | resume_error(L, "cannot resume non-suspended coroutine", firstArg); | |
578 | /* coroutine is in base level; start running it */ | |
579 | if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */ | |
580 | luaV_execute(L); /* call it */ | |
581 | } | |
582 | else if (L->status != LUA_YIELD) | |
583 | resume_error(L, "cannot resume dead coroutine", firstArg); | |
584 | else { /* resuming from previous yield */ | |
585 | L->status = LUA_OK; | |
586 | ci->func = restorestack(L, ci->extra); | |
587 | if (isLua(ci)) /* yielded inside a hook? */ | |
588 | luaV_execute(L); /* just continue running Lua code */ | |
589 | else { /* 'common' yield */ | |
590 | if (ci->u.c.k != NULL) { /* does it have a continuation? */ | |
591 | int n; | |
592 | ci->u.c.status = LUA_YIELD; /* 'default' status */ | |
593 | ci->callstatus |= CIST_YIELDED; | |
594 | lua_unlock(L); | |
595 | n = (*ci->u.c.k)(L); /* call continuation */ | |
596 | lua_lock(L); | |
597 | api_checknelems(L, n); | |
598 | firstArg = L->top - n; /* yield results come from continuation */ | |
599 | } | |
600 | luaD_poscall(L, firstArg); /* finish 'luaD_precall' */ | |
601 | } | |
602 | unroll(L, NULL); | |
603 | } | |
604 | lua_assert(nCcalls == L->nCcalls); | |
605 | } | |
606 | ||
607 | ||
608 | LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) { | |
609 | int status; | |
610 | int oldnny = L->nny; /* save 'nny' */ | |
611 | lua_lock(L); | |
612 | luai_userstateresume(L, nargs); | |
613 | L->nCcalls = (from) ? from->nCcalls + 1 : 1; | |
614 | L->nny = 0; /* allow yields */ | |
615 | api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs); | |
616 | status = luaD_rawrunprotected(L, resume_cb, L->top - nargs); | |
617 | if (status == -1) /* error calling 'lua_resume'? */ | |
618 | status = LUA_ERRRUN; | |
619 | else { /* yield or regular error */ | |
620 | while (status != LUA_OK && status != LUA_YIELD) { /* error? */ | |
621 | if (recover(L, status)) /* recover point? */ | |
622 | status = luaD_rawrunprotected(L, unroll, NULL); /* run continuation */ | |
623 | else { /* unrecoverable error */ | |
624 | L->status = cast_byte(status); /* mark thread as `dead' */ | |
625 | seterrorobj(L, status, L->top); | |
626 | L->ci->top = L->top; | |
627 | break; | |
628 | } | |
629 | } | |
630 | lua_assert(status == L->status); | |
631 | } | |
632 | L->nny = oldnny; /* restore 'nny' */ | |
633 | L->nCcalls--; | |
634 | lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0)); | |
635 | lua_unlock(L); | |
636 | return status; | |
637 | } | |
638 | ||
639 | ||
640 | LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) { | |
641 | CallInfo *ci = L->ci; | |
642 | luai_userstateyield(L, nresults); | |
643 | lua_lock(L); | |
644 | api_checknelems(L, nresults); | |
645 | if (L->nny > 0) { | |
646 | if (L != G(L)->mainthread) | |
647 | luaG_runerror(L, "attempt to yield across a C-call boundary"); | |
648 | else | |
649 | luaG_runerror(L, "attempt to yield from outside a coroutine"); | |
650 | } | |
651 | L->status = LUA_YIELD; | |
652 | ci->extra = savestack(L, ci->func); /* save current 'func' */ | |
653 | if (isLua(ci)) { /* inside a hook? */ | |
654 | api_check(L, k == NULL, "hooks cannot continue after yielding"); | |
655 | } | |
656 | else { | |
657 | if ((ci->u.c.k = k) != NULL) /* is there a continuation? */ | |
658 | ci->u.c.ctx = ctx; /* save context */ | |
659 | ci->func = L->top - nresults - 1; /* protect stack below results */ | |
660 | luaD_throw(L, LUA_YIELD); | |
661 | } | |
662 | lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */ | |
663 | lua_unlock(L); | |
664 | return 0; /* return to 'luaD_hook' */ | |
665 | } | |
666 | ||
667 | ||
668 | int luaD_pcall (lua_State *L, Pfunc func, void *u, | |
669 | ptrdiff_t old_top, ptrdiff_t ef) { | |
670 | int status; | |
671 | CallInfo *old_ci = L->ci; | |
672 | lu_byte old_allowhooks = L->allowhook; | |
673 | unsigned short old_nny = L->nny; | |
674 | ptrdiff_t old_errfunc = L->errfunc; | |
675 | L->errfunc = ef; | |
676 | status = luaD_rawrunprotected(L, func, u); | |
677 | if (status != LUA_OK) { /* an error occurred? */ | |
678 | StkId oldtop = restorestack(L, old_top); | |
679 | luaF_close(L, oldtop); /* close possible pending closures */ | |
680 | seterrorobj(L, status, oldtop); | |
681 | L->ci = old_ci; | |
682 | L->allowhook = old_allowhooks; | |
683 | L->nny = old_nny; | |
684 | luaD_shrinkstack(L); | |
685 | } | |
686 | L->errfunc = old_errfunc; | |
687 | return status; | |
688 | } | |
689 | ||
690 | ||
691 | ||
692 | /* | |
693 | ** Execute a protected parser. | |
694 | */ | |
695 | struct SParser { /* data to `f_parser' */ | |
696 | ZIO *z; | |
697 | Mbuffer buff; /* dynamic structure used by the scanner */ | |
698 | Dyndata dyd; /* dynamic structures used by the parser */ | |
699 | const char *mode; | |
700 | const char *name; | |
701 | }; | |
702 | ||
703 | ||
704 | static void checkmode (lua_State *L, const char *mode, const char *x) { | |
705 | if (mode && strchr(mode, x[0]) == NULL) { | |
706 | luaO_pushfstring(L, | |
707 | "attempt to load a %s chunk (mode is " LUA_QS ")", x, mode); | |
708 | luaD_throw(L, LUA_ERRSYNTAX); | |
709 | } | |
710 | } | |
711 | ||
712 | ||
713 | static void f_parser (lua_State *L, void *ud) { | |
714 | int i; | |
715 | Closure *cl; | |
716 | struct SParser *p = cast(struct SParser *, ud); | |
717 | int c = zgetc(p->z); /* read first character */ | |
fc5d4b67 DB |
718 | lua_assert(c != LUA_SIGNATURE[0]); /* binary not supported */ |
719 | checkmode(L, p->mode, "text"); | |
720 | cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c); | |
d99a0153 CW |
721 | lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues); |
722 | for (i = 0; i < cl->l.nupvalues; i++) { /* initialize upvalues */ | |
723 | UpVal *up = luaF_newupval(L); | |
724 | cl->l.upvals[i] = up; | |
725 | luaC_objbarrier(L, cl, up); | |
726 | } | |
727 | } | |
728 | ||
729 | ||
730 | int luaD_protectedparser (lua_State *L, ZIO *z, const char *name, | |
731 | const char *mode) { | |
732 | struct SParser p; | |
733 | int status; | |
734 | L->nny++; /* cannot yield during parsing */ | |
735 | p.z = z; p.name = name; p.mode = mode; | |
736 | p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0; | |
737 | p.dyd.gt.arr = NULL; p.dyd.gt.size = 0; | |
738 | p.dyd.label.arr = NULL; p.dyd.label.size = 0; | |
739 | luaZ_initbuffer(L, &p.buff); | |
740 | status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc); | |
741 | luaZ_freebuffer(L, &p.buff); | |
742 | luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size); | |
743 | luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size); | |
744 | luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size); | |
745 | L->nny--; | |
746 | return status; | |
747 | } |