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1 /*
2 ** $Id: lfunc.c $
3 ** Auxiliary functions to manipulate prototypes and closures
4 ** See Copyright Notice in lua.h
5 */
6 
7 #define lfunc_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 "lfunc.h"
20 #include "lgc.h"
21 #include "lmem.h"
22 #include "lobject.h"
23 #include "lstate.h"
24 
25 
26 
luaF_newCclosure(lua_State * L,int nupvals)27 CClosure *luaF_newCclosure (lua_State *L, int nupvals) {
28   GCObject *o = luaC_newobj(L, LUA_VCCL, sizeCclosure(nupvals));
29   CClosure *c = gco2ccl(o);
30   c->nupvalues = cast_byte(nupvals);
31   return c;
32 }
33 
34 
luaF_newLclosure(lua_State * L,int nupvals)35 LClosure *luaF_newLclosure (lua_State *L, int nupvals) {
36   GCObject *o = luaC_newobj(L, LUA_VLCL, sizeLclosure(nupvals));
37   LClosure *c = gco2lcl(o);
38   c->p = NULL;
39   c->nupvalues = cast_byte(nupvals);
40   while (nupvals--) c->upvals[nupvals] = NULL;
41   return c;
42 }
43 
44 
45 /*
46 ** fill a closure with new closed upvalues
47 */
luaF_initupvals(lua_State * L,LClosure * cl)48 void luaF_initupvals (lua_State *L, LClosure *cl) {
49   int i;
50   for (i = 0; i < cl->nupvalues; i++) {
51     GCObject *o = luaC_newobj(L, LUA_VUPVAL, sizeof(UpVal));
52     UpVal *uv = gco2upv(o);
53     uv->v = &uv->u.value;  /* make it closed */
54     setnilvalue(uv->v);
55     cl->upvals[i] = uv;
56     luaC_objbarrier(L, cl, o);
57   }
58 }
59 
60 
61 /*
62 ** Create a new upvalue at the given level, and link it to the list of
63 ** open upvalues of 'L' after entry 'prev'.
64 **/
newupval(lua_State * L,int tbc,StkId level,UpVal ** prev)65 static UpVal *newupval (lua_State *L, int tbc, StkId level, UpVal **prev) {
66   GCObject *o = luaC_newobj(L, LUA_VUPVAL, sizeof(UpVal));
67   UpVal *uv = gco2upv(o);
68   UpVal *next = *prev;
69   uv->v = s2v(level);  /* current value lives in the stack */
70   uv->tbc = tbc;
71   uv->u.open.next = next;  /* link it to list of open upvalues */
72   uv->u.open.previous = prev;
73   if (next)
74     next->u.open.previous = &uv->u.open.next;
75   *prev = uv;
76   if (!isintwups(L)) {  /* thread not in list of threads with upvalues? */
77     L->twups = G(L)->twups;  /* link it to the list */
78     G(L)->twups = L;
79   }
80   return uv;
81 }
82 
83 
84 /*
85 ** Find and reuse, or create if it does not exist, an upvalue
86 ** at the given level.
87 */
luaF_findupval(lua_State * L,StkId level)88 UpVal *luaF_findupval (lua_State *L, StkId level) {
89   UpVal **pp = &L->openupval;
90   UpVal *p;
91   lua_assert(isintwups(L) || L->openupval == NULL);
92   while ((p = *pp) != NULL && uplevel(p) >= level) {  /* search for it */
93     lua_assert(!isdead(G(L), p));
94     if (uplevel(p) == level)  /* corresponding upvalue? */
95       return p;  /* return it */
96     pp = &p->u.open.next;
97   }
98   /* not found: create a new upvalue after 'pp' */
99   return newupval(L, 0, level, pp);
100 }
101 
102 
callclose(lua_State * L,void * ud)103 static void callclose (lua_State *L, void *ud) {
104   UNUSED(ud);
105   luaD_callnoyield(L, L->top - 3, 0);
106 }
107 
108 
109 /*
110 ** Prepare closing method plus its arguments for object 'obj' with
111 ** error message 'err'. (This function assumes EXTRA_STACK.)
112 */
prepclosingmethod(lua_State * L,TValue * obj,TValue * err)113 static int prepclosingmethod (lua_State *L, TValue *obj, TValue *err) {
114   StkId top = L->top;
115   const TValue *tm = luaT_gettmbyobj(L, obj, TM_CLOSE);
116   if (ttisnil(tm))  /* no metamethod? */
117     return 0;  /* nothing to call */
118   setobj2s(L, top, tm);  /* will call metamethod... */
119   setobj2s(L, top + 1, obj);  /* with 'self' as the 1st argument */
120   setobj2s(L, top + 2, err);  /* and error msg. as 2nd argument */
121   L->top = top + 3;  /* add function and arguments */
122   return 1;
123 }
124 
125 
126 /*
127 ** Raise an error with message 'msg', inserting the name of the
128 ** local variable at position 'level' in the stack.
129 */
varerror(lua_State * L,StkId level,const char * msg)130 static void varerror (lua_State *L, StkId level, const char *msg) {
131   int idx = cast_int(level - L->ci->func);
132   const char *vname = luaG_findlocal(L, L->ci, idx, NULL);
133   if (vname == NULL) vname = "?";
134   luaG_runerror(L, msg, vname);
135 }
136 
137 
138 /*
139 ** Prepare and call a closing method. If status is OK, code is still
140 ** inside the original protected call, and so any error will be handled
141 ** there. Otherwise, a previous error already activated the original
142 ** protected call, and so the call to the closing method must be
143 ** protected here. (A status == CLOSEPROTECT behaves like a previous
144 ** error, to also run the closing method in protected mode).
145 ** If status is OK, the call to the closing method will be pushed
146 ** at the top of the stack. Otherwise, values are pushed after
147 ** the 'level' of the upvalue being closed, as everything after
148 ** that won't be used again.
149 */
callclosemth(lua_State * L,StkId level,int status)150 static int callclosemth (lua_State *L, StkId level, int status) {
151   TValue *uv = s2v(level);  /* value being closed */
152   if (likely(status == LUA_OK)) {
153     if (prepclosingmethod(L, uv, &G(L)->nilvalue))  /* something to call? */
154       callclose(L, NULL);  /* call closing method */
155     else if (!l_isfalse(uv))  /* non-closable non-false value? */
156       varerror(L, level, "attempt to close non-closable variable '%s'");
157   }
158   else {  /* must close the object in protected mode */
159     ptrdiff_t oldtop;
160     level++;  /* space for error message */
161     oldtop = savestack(L, level + 1);  /* top will be after that */
162     luaD_seterrorobj(L, status, level);  /* set error message */
163     if (prepclosingmethod(L, uv, s2v(level))) {  /* something to call? */
164       int newstatus = luaD_pcall(L, callclose, NULL, oldtop, 0);
165       if (newstatus != LUA_OK && status == CLOSEPROTECT)  /* first error? */
166         status = newstatus;  /* this will be the new error */
167       else {
168         if (newstatus != LUA_OK)  /* suppressed error? */
169           luaE_warnerror(L, "__close metamethod");
170         /* leave original error (or nil) on top */
171         L->top = restorestack(L, oldtop);
172       }
173     }
174     /* else no metamethod; ignore this case and keep original error */
175   }
176   return status;
177 }
178 
179 
180 /*
181 ** Try to create a to-be-closed upvalue
182 ** (can raise a memory-allocation error)
183 */
trynewtbcupval(lua_State * L,void * ud)184 static void trynewtbcupval (lua_State *L, void *ud) {
185   newupval(L, 1, cast(StkId, ud), &L->openupval);
186 }
187 
188 
189 /*
190 ** Create a to-be-closed upvalue. If there is a memory error
191 ** when creating the upvalue, the closing method must be called here,
192 ** as there is no upvalue to call it later.
193 */
luaF_newtbcupval(lua_State * L,StkId level)194 void luaF_newtbcupval (lua_State *L, StkId level) {
195   TValue *obj = s2v(level);
196   lua_assert(L->openupval == NULL || uplevel(L->openupval) < level);
197   if (!l_isfalse(obj)) {  /* false doesn't need to be closed */
198     int status;
199     const TValue *tm = luaT_gettmbyobj(L, obj, TM_CLOSE);
200     if (ttisnil(tm))  /* no metamethod? */
201       varerror(L, level, "variable '%s' got a non-closable value");
202     status = luaD_rawrunprotected(L, trynewtbcupval, level);
203     if (unlikely(status != LUA_OK)) {  /* memory error creating upvalue? */
204       lua_assert(status == LUA_ERRMEM);
205       luaD_seterrorobj(L, LUA_ERRMEM, level + 1);  /* save error message */
206       /* next call must succeed, as object is closable */
207       prepclosingmethod(L, s2v(level), s2v(level + 1));
208       callclose(L, NULL);  /* call closing method */
209       luaD_throw(L, LUA_ERRMEM);  /* throw memory error */
210     }
211   }
212 }
213 
214 
luaF_unlinkupval(UpVal * uv)215 void luaF_unlinkupval (UpVal *uv) {
216   lua_assert(upisopen(uv));
217   *uv->u.open.previous = uv->u.open.next;
218   if (uv->u.open.next)
219     uv->u.open.next->u.open.previous = uv->u.open.previous;
220 }
221 
222 
luaF_close(lua_State * L,StkId level,int status)223 int luaF_close (lua_State *L, StkId level, int status) {
224   UpVal *uv;
225   while ((uv = L->openupval) != NULL && uplevel(uv) >= level) {
226     TValue *slot = &uv->u.value;  /* new position for value */
227     lua_assert(uplevel(uv) < L->top);
228     if (uv->tbc && status != NOCLOSINGMETH) {
229       /* must run closing method, which may change the stack */
230       ptrdiff_t levelrel = savestack(L, level);
231       status = callclosemth(L, uplevel(uv), status);
232       level = restorestack(L, levelrel);
233     }
234     luaF_unlinkupval(uv);
235     setobj(L, slot, uv->v);  /* move value to upvalue slot */
236     uv->v = slot;  /* now current value lives here */
237     if (!iswhite(uv)) {  /* neither white nor dead? */
238       nw2black(uv);  /* closed upvalues cannot be gray */
239       luaC_barrier(L, uv, slot);
240     }
241   }
242   return status;
243 }
244 
245 
luaF_newproto(lua_State * L)246 Proto *luaF_newproto (lua_State *L) {
247   GCObject *o = luaC_newobj(L, LUA_VPROTO, sizeof(Proto));
248   Proto *f = gco2p(o);
249   f->k = NULL;
250   f->sizek = 0;
251   f->p = NULL;
252   f->sizep = 0;
253   f->code = NULL;
254   f->sizecode = 0;
255   f->lineinfo = NULL;
256   f->sizelineinfo = 0;
257   f->abslineinfo = NULL;
258   f->sizeabslineinfo = 0;
259   f->upvalues = NULL;
260   f->sizeupvalues = 0;
261   f->numparams = 0;
262   f->is_vararg = 0;
263   f->maxstacksize = 0;
264   f->locvars = NULL;
265   f->sizelocvars = 0;
266   f->linedefined = 0;
267   f->lastlinedefined = 0;
268   f->source = NULL;
269   return f;
270 }
271 
272 
luaF_freeproto(lua_State * L,Proto * f)273 void luaF_freeproto (lua_State *L, Proto *f) {
274   luaM_freearray(L, f->code, f->sizecode);
275   luaM_freearray(L, f->p, f->sizep);
276   luaM_freearray(L, f->k, f->sizek);
277   luaM_freearray(L, f->lineinfo, f->sizelineinfo);
278   luaM_freearray(L, f->abslineinfo, f->sizeabslineinfo);
279   luaM_freearray(L, f->locvars, f->sizelocvars);
280   luaM_freearray(L, f->upvalues, f->sizeupvalues);
281   luaM_free(L, f);
282 }
283 
284 
285 /*
286 ** Look for n-th local variable at line 'line' in function 'func'.
287 ** Returns NULL if not found.
288 */
luaF_getlocalname(const Proto * f,int local_number,int pc)289 const char *luaF_getlocalname (const Proto *f, int local_number, int pc) {
290   int i;
291   for (i = 0; i<f->sizelocvars && f->locvars[i].startpc <= pc; i++) {
292     if (pc < f->locvars[i].endpc) {  /* is variable active? */
293       local_number--;
294       if (local_number == 0)
295         return getstr(f->locvars[i].varname);
296     }
297   }
298   return NULL;  /* not found */
299 }
300 
301