Commit message: Fixed bug: invalid 'oldpc' when returning to a function

The field 'L->oldpc' is not always updated when control returns to a
function; an invalid value can seg. fault when computing 'changedline'.
(One example is an error in a finalizer; control can return to
'luaV_execute' without executing 'luaD_poscall'.) Instead of trying to
fix all possible corner cases, it seems safer to be resilient to invalid
values for 'oldpc'. Valid but wrong values at most cause an extra call
to a line hook.
CVE: CVE-2020-15945
CWE: CWE-703
Vulnerability description: Lua through 5.4.0 has a segmentation fault in changedline in ldebug.c (e.g., when called by luaG_traceexec) because it incorrectly expects that an oldpc value is always updated upon a return of the flow of control to a function.

Project: lua

LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
  int i;
  lua_State *L;
  global_State *g;
  LG *l = cast(LG *, (*f)(ud, NULL, LUA_TTHREAD, sizeof(LG)));
  if (l == NULL) return NULL;
  L = &l->l.l;
  g = &l->g;
  L->tt = LUA_VTHREAD;
  g->currentwhite = bitmask(WHITE0BIT);
  L->marked = luaC_white(g);
  preinit_thread(L, g);
  g->allgc = obj2gco(L);  /* by now, only object is the main thread */
  L->next = NULL;
  g->Cstacklimit = L->nCcalls = LUAI_MAXCSTACK + CSTACKERR;
  incnny(L);  /* main thread is always non yieldable */
  g->frealloc = f;
  g->ud = ud;
  g->warnf = NULL;
  g->ud_warn = NULL;
  g->mainthread = L;
  g->seed = luai_makeseed(L);
  g->gcrunning = 0;  /* no GC while building state */
  g->strt.size = g->strt.nuse = 0;
  g->strt.hash = NULL;
  setnilvalue(&g->l_registry);
  g->panic = NULL;
  g->gcstate = GCSpause;
  g->gckind = KGC_INC;
  g->gcemergency = 0;
  g->finobj = g->tobefnz = g->fixedgc = NULL;
  g->survival = g->old = g->reallyold = NULL;
  g->finobjsur = g->finobjold = g->finobjrold = NULL;
  g->sweepgc = NULL;
  g->gray = g->grayagain = NULL;
  g->weak = g->ephemeron = g->allweak = NULL;
  g->twups = NULL;
  g->totalbytes = sizeof(LG);
  g->GCdebt = 0;
  g->lastatomic = 0;
  setivalue(&g->nilvalue, 0);  /* to signal that state is not yet built */
  setgcparam(g->gcpause, LUAI_GCPAUSE);
  setgcparam(g->gcstepmul, LUAI_GCMUL);
  g->gcstepsize = LUAI_GCSTEPSIZE;
  setgcparam(g->genmajormul, LUAI_GENMAJORMUL);
  g->genminormul = LUAI_GENMINORMUL;
  for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
  if (luaD_rawrunprotected(L, f_luaopen, NULL) != LUA_OK) {
    /* memory allocation error: free partial state */
    close_state(L);
    L = NULL;
  }
  return L;
}

Project: lua

int lua_resetthread (lua_State *L) {
  CallInfo *ci;
  int status;
  lua_lock(L);
  L->ci = ci = &L->base_ci;  /* unwind CallInfo list */
  setnilvalue(s2v(L->stack));  /* 'function' entry for basic 'ci' */
  ci->func = L->stack;
  ci->callstatus = CIST_C;
  status = luaF_close(L, L->stack, CLOSEPROTECT);
  if (status != CLOSEPROTECT)  /* real errors? */
    luaD_seterrorobj(L, status, L->stack + 1);
  else {
    status = LUA_OK;
    L->top = L->stack + 1;
  }
  ci->top = L->top + LUA_MINSTACK;
  L->status = status;
  lua_unlock(L);
  return status;
}

Project: lua

LUA_API void lua_close (lua_State *L) {
  lua_lock(L);
  L = G(L)->mainthread;  /* only the main thread can be closed */
  close_state(L);
}

Project: lua

LUA_API lua_State *lua_newthread (lua_State *L) {
  global_State *g;
  lua_State *L1;
  lua_lock(L);
  g = G(L);
  luaC_checkGC(L);
  /* create new thread */
  L1 = &cast(LX *, luaM_newobject(L, LUA_TTHREAD, sizeof(LX)))->l;
  L1->marked = luaC_white(g);
  L1->tt = LUA_VTHREAD;
  /* link it on list 'allgc' */
  L1->next = g->allgc;
  g->allgc = obj2gco(L1);
  /* anchor it on L stack */
  setthvalue2s(L, L->top, L1);
  api_incr_top(L);
  preinit_thread(L1, g);
  L1->nCcalls = getCcalls(L);
  L1->hookmask = L->hookmask;
  L1->basehookcount = L->basehookcount;
  L1->hook = L->hook;
  resethookcount(L1);
  /* initialize L1 extra space */
  memcpy(lua_getextraspace(L1), lua_getextraspace(g->mainthread),
         LUA_EXTRASPACE);
  luai_userstatethread(L, L1);
  stack_init(L1, L);  /* init stack */
  lua_unlock(L);
  return L1;
}

Project: lua

void luaE_freeCI (lua_State *L) {
  CallInfo *ci = L->ci;
  CallInfo *next = ci->next;
  ci->next = NULL;
  L->nCcalls += L->nci;  /* add removed elements back to 'nCcalls' */
  while ((ci = next) != NULL) {
    next = ci->next;
    luaM_free(L, ci);
    L->nci--;
  }
  L->nCcalls -= L->nci;  /* adjust result */
}

Project: lua

void luaE_enterCcall (lua_State *L) {
  int ncalls = getCcalls(L);
  L->nCcalls--;
  if (ncalls <= CSTACKERR) {  /* possible overflow? */
    luaE_freeCI(L);  /* release unused CIs */
    ncalls = getCcalls(L);  /* update call count */
    if (ncalls <= CSTACKERR) {  /* still overflow? */
      if (ncalls <= CSTACKERRMARK)  /* below error-handling zone? */
        luaD_throw(L, LUA_ERRERR);  /* error while handling stack error */
      else if (ncalls >= CSTACKMARK) {
        /* not in error-handling zone; raise the error now */
        L->nCcalls = (CSTACKMARK - 1);  /* enter error-handling zone */
        luaG_runerror(L, "C stack overflow");
      }
      /* else stack is in the error-handling zone;
         allow message handler to work */
    }
  }
}

Project: lua

CallInfo *luaE_extendCI (lua_State *L) {
  CallInfo *ci;
  lua_assert(L->ci->next == NULL);
  luaE_enterCcall(L);
  ci = luaM_new(L, CallInfo);
  lua_assert(L->ci->next == NULL);
  L->ci->next = ci;
  ci->previous = L->ci;
  ci->next = NULL;
  ci->u.l.trap = 0;
  L->nci++;
  return ci;
}

Project: lua

void luaV_execute (lua_State *L, CallInfo *ci) {
  LClosure *cl;
  TValue *k;
  StkId base;
  const Instruction *pc;
  int trap;
#if LUA_USE_JUMPTABLE
#include "ljumptab.h"
#endif
 tailcall:
  trap = L->hookmask;
  cl = clLvalue(s2v(ci->func));
  k = cl->p->k;
  pc = ci->u.l.savedpc;
  if (trap) {
    if (cl->p->is_vararg)
      trap = 0;  /* hooks will start after VARARGPREP instruction */
    else if (pc == cl->p->code)  /* first instruction (not resuming)? */
      luaD_hookcall(L, ci);
    ci->u.l.trap = 1;  /* there may be other hooks */
  }
  base = ci->func + 1;
  /* main loop of interpreter */
  for (;;) {
    Instruction i;  /* instruction being executed */
    StkId ra;  /* instruction's A register */
    vmfetch();
    lua_assert(base == ci->func + 1);
    lua_assert(base <= L->top && L->top < L->stack + L->stacksize);
    /* invalidate top for instructions not expecting it */
    lua_assert(isIT(i) || (cast_void(L->top = base), 1));
    vmdispatch (GET_OPCODE(i)) {
      vmcase(OP_MOVE) {
        setobjs2s(L, ra, RB(i));
        vmbreak;
      }
      vmcase(OP_LOADI) {
        lua_Integer b = GETARG_sBx(i);
        setivalue(s2v(ra), b);
        vmbreak;
      }
      vmcase(OP_LOADF) {
        int b = GETARG_sBx(i);
        setfltvalue(s2v(ra), cast_num(b));
        vmbreak;
      }
      vmcase(OP_LOADK) {
        TValue *rb = k + GETARG_Bx(i);
        setobj2s(L, ra, rb);
        vmbreak;
      }
      vmcase(OP_LOADKX) {
        TValue *rb;
        rb = k + GETARG_Ax(*pc); pc++;
        setobj2s(L, ra, rb);
        vmbreak;
      }
      vmcase(OP_LOADFALSE) {
        setbfvalue(s2v(ra));
        vmbreak;
      }
      vmcase(OP_LFALSESKIP) {
        setbfvalue(s2v(ra));
        pc++;  /* skip next instruction */
        vmbreak;
      }
      vmcase(OP_LOADTRUE) {
        setbtvalue(s2v(ra));
        vmbreak;
      }
      vmcase(OP_LOADNIL) {
        int b = GETARG_B(i);
        do {
          setnilvalue(s2v(ra++));
        } while (b--);
        vmbreak;
      }
      vmcase(OP_GETUPVAL) {
        int b = GETARG_B(i);
        setobj2s(L, ra, cl->upvals[b]->v);
        vmbreak;
      }
      vmcase(OP_SETUPVAL) {
        UpVal *uv = cl->upvals[GETARG_B(i)];
        setobj(L, uv->v, s2v(ra));
        luaC_barrier(L, uv, s2v(ra));
        vmbreak;
      }
      vmcase(OP_GETTABUP) {
        const TValue *slot;
        TValue *upval = cl->upvals[GETARG_B(i)]->v;
        TValue *rc = KC(i);
        TString *key = tsvalue(rc);  /* key must be a string */
        if (luaV_fastget(L, upval, key, slot, luaH_getshortstr)) {
          setobj2s(L, ra, slot);
        }
        else
          Protect(luaV_finishget(L, upval, rc, ra, slot));
        vmbreak;
      }
      vmcase(OP_GETTABLE) {
        const TValue *slot;
        TValue *rb = vRB(i);
        TValue *rc = vRC(i);
        lua_Unsigned n;
        if (ttisinteger(rc)  /* fast track for integers? */
            ? (cast_void(n = ivalue(rc)), luaV_fastgeti(L, rb, n, slot))
            : luaV_fastget(L, rb, rc, slot, luaH_get)) {
          setobj2s(L, ra, slot);
        }
        else
          Protect(luaV_finishget(L, rb, rc, ra, slot));
        vmbreak;
      }
      vmcase(OP_GETI) {
        const TValue *slot;
        TValue *rb = vRB(i);
        int c = GETARG_C(i);
        if (luaV_fastgeti(L, rb, c, slot)) {
          setobj2s(L, ra, slot);
        }
        else {
          TValue key;
          setivalue(&key, c);
          Protect(luaV_finishget(L, rb, &key, ra, slot));
        }
        vmbreak;
      }
      vmcase(OP_GETFIELD) {
        const TValue *slot;
        TValue *rb = vRB(i);
        TValue *rc = KC(i);
        TString *key = tsvalue(rc);  /* key must be a string */
        if (luaV_fastget(L, rb, key, slot, luaH_getshortstr)) {
          setobj2s(L, ra, slot);
        }
        else
          Protect(luaV_finishget(L, rb, rc, ra, slot));
        vmbreak;
      }
      vmcase(OP_SETTABUP) {
        const TValue *slot;
        TValue *upval = cl->upvals[GETARG_A(i)]->v;
        TValue *rb = KB(i);
        TValue *rc = RKC(i);
        TString *key = tsvalue(rb);  /* key must be a string */
        if (luaV_fastget(L, upval, key, slot, luaH_getshortstr)) {
          luaV_finishfastset(L, upval, slot, rc);
        }
        else
          Protect(luaV_finishset(L, upval, rb, rc, slot));
        vmbreak;
      }
      vmcase(OP_SETTABLE) {
        const TValue *slot;
        TValue *rb = vRB(i);  /* key (table is in 'ra') */
        TValue *rc = RKC(i);  /* value */
        lua_Unsigned n;
        if (ttisinteger(rb)  /* fast track for integers? */
            ? (cast_void(n = ivalue(rb)), luaV_fastgeti(L, s2v(ra), n, slot))
            : luaV_fastget(L, s2v(ra), rb, slot, luaH_get)) {
          luaV_finishfastset(L, s2v(ra), slot, rc);
        }
        else
          Protect(luaV_finishset(L, s2v(ra), rb, rc, slot));
        vmbreak;
      }
      vmcase(OP_SETI) {
        const TValue *slot;
        int c = GETARG_B(i);
        TValue *rc = RKC(i);
        if (luaV_fastgeti(L, s2v(ra), c, slot)) {
          luaV_finishfastset(L, s2v(ra), slot, rc);
        }
        else {
          TValue key;
          setivalue(&key, c);
          Protect(luaV_finishset(L, s2v(ra), &key, rc, slot));
        }
        vmbreak;
      }
      vmcase(OP_SETFIELD) {
        const TValue *slot;
        TValue *rb = KB(i);
        TValue *rc = RKC(i);
        TString *key = tsvalue(rb);  /* key must be a string */
        if (luaV_fastget(L, s2v(ra), key, slot, luaH_getshortstr)) {
          luaV_finishfastset(L, s2v(ra), slot, rc);
        }
        else
          Protect(luaV_finishset(L, s2v(ra), rb, rc, slot));
        vmbreak;
      }
      vmcase(OP_NEWTABLE) {
        int b = GETARG_B(i);  /* log2(hash size) + 1 */
        int c = GETARG_C(i);  /* array size */
        Table *t;
        if (b > 0)
          b = 1 << (b - 1);  /* size is 2^(b - 1) */
        lua_assert((!TESTARG_k(i)) == (GETARG_Ax(*pc) == 0));
        if (TESTARG_k(i))  /* non-zero extra argument? */
          c += GETARG_Ax(*pc) * (MAXARG_C + 1);  /* add it to size */
        pc++;  /* skip extra argument */
        L->top = ra + 1;  /* correct top in case of emergency GC */
        t = luaH_new(L);  /* memory allocation */
        sethvalue2s(L, ra, t);
        if (b != 0 || c != 0)
          luaH_resize(L, t, c, b);  /* idem */
        checkGC(L, ra + 1);
        vmbreak;
      }
      vmcase(OP_SELF) {
        const TValue *slot;
        TValue *rb = vRB(i);
        TValue *rc = RKC(i);
        TString *key = tsvalue(rc);  /* key must be a string */
        setobj2s(L, ra + 1, rb);
        if (luaV_fastget(L, rb, key, slot, luaH_getstr)) {
          setobj2s(L, ra, slot);
        }
        else
          Protect(luaV_finishget(L, rb, rc, ra, slot));
        vmbreak;
      }
      vmcase(OP_ADDI) {
        op_arithI(L, l_addi, luai_numadd);
        vmbreak;
      }
      vmcase(OP_ADDK) {
        op_arithK(L, l_addi, luai_numadd);
        vmbreak;
      }
      vmcase(OP_SUBK) {
        op_arithK(L, l_subi, luai_numsub);
        vmbreak;
      }
      vmcase(OP_MULK) {
        op_arithK(L, l_muli, luai_nummul);
        vmbreak;
      }
      vmcase(OP_MODK) {
        op_arithK(L, luaV_mod, luaV_modf);
        vmbreak;
      }
      vmcase(OP_POWK) {
        op_arithfK(L, luai_numpow);
        vmbreak;
      }
      vmcase(OP_DIVK) {
        op_arithfK(L, luai_numdiv);
        vmbreak;
      }
      vmcase(OP_IDIVK) {
        op_arithK(L, luaV_idiv, luai_numidiv);
        vmbreak;
      }
      vmcase(OP_BANDK) {
        op_bitwiseK(L, l_band);
        vmbreak;
      }
      vmcase(OP_BORK) {
        op_bitwiseK(L, l_bor);
        vmbreak;
      }
      vmcase(OP_BXORK) {
        op_bitwiseK(L, l_bxor);
        vmbreak;
      }
      vmcase(OP_SHRI) {
        TValue *rb = vRB(i);
        int ic = GETARG_sC(i);
        lua_Integer ib;
        if (tointegerns(rb, &ib)) {
          pc++; setivalue(s2v(ra), luaV_shiftl(ib, -ic));
        }
        vmbreak;
      }
      vmcase(OP_SHLI) {
        TValue *rb = vRB(i);
        int ic = GETARG_sC(i);
        lua_Integer ib;
        if (tointegerns(rb, &ib)) {
          pc++; setivalue(s2v(ra), luaV_shiftl(ic, ib));
        }
        vmbreak;
      }
      vmcase(OP_ADD) {
        op_arith(L, l_addi, luai_numadd);
        vmbreak;
      }
      vmcase(OP_SUB) {
        op_arith(L, l_subi, luai_numsub);
        vmbreak;
      }
      vmcase(OP_MUL) {
        op_arith(L, l_muli, luai_nummul);
        vmbreak;
      }
      vmcase(OP_MOD) {
        op_arith(L, luaV_mod, luaV_modf);
        vmbreak;
      }
      vmcase(OP_POW) {
        op_arithf(L, luai_numpow);
        vmbreak;
      }
      vmcase(OP_DIV) {  /* float division (always with floats) */
        op_arithf(L, luai_numdiv);
        vmbreak;
      }
      vmcase(OP_IDIV) {  /* floor division */
        op_arith(L, luaV_idiv, luai_numidiv);
        vmbreak;
      }
      vmcase(OP_BAND) {
        op_bitwise(L, l_band);
        vmbreak;
      }
      vmcase(OP_BOR) {
        op_bitwise(L, l_bor);
        vmbreak;
      }
      vmcase(OP_BXOR) {
        op_bitwise(L, l_bxor);
        vmbreak;
      }
      vmcase(OP_SHR) {
        op_bitwise(L, luaV_shiftr);
        vmbreak;
      }
      vmcase(OP_SHL) {
        op_bitwise(L, luaV_shiftl);
        vmbreak;
      }
      vmcase(OP_MMBIN) {
        Instruction pi = *(pc - 2);  /* original arith. expression */
        TValue *rb = vRB(i);
        TMS tm = (TMS)GETARG_C(i);
        StkId result = RA(pi);
        lua_assert(OP_ADD <= GET_OPCODE(pi) && GET_OPCODE(pi) <= OP_SHR);
        Protect(luaT_trybinTM(L, s2v(ra), rb, result, tm));
        vmbreak;
      }
      vmcase(OP_MMBINI) {
        Instruction pi = *(pc - 2);  /* original arith. expression */
        int imm = GETARG_sB(i);
        TMS tm = (TMS)GETARG_C(i);
        int flip = GETARG_k(i);
        StkId result = RA(pi);
        Protect(luaT_trybiniTM(L, s2v(ra), imm, flip, result, tm));
        vmbreak;
      }
      vmcase(OP_MMBINK) {
        Instruction pi = *(pc - 2);  /* original arith. expression */
        TValue *imm = KB(i);
        TMS tm = (TMS)GETARG_C(i);
        int flip = GETARG_k(i);
        StkId result = RA(pi);
        Protect(luaT_trybinassocTM(L, s2v(ra), imm, flip, result, tm));
        vmbreak;
      }
      vmcase(OP_UNM) {
        TValue *rb = vRB(i);
        lua_Number nb;
        if (ttisinteger(rb)) {
          lua_Integer ib = ivalue(rb);
          setivalue(s2v(ra), intop(-, 0, ib));
        }
        else if (tonumberns(rb, nb)) {
          setfltvalue(s2v(ra), luai_numunm(L, nb));
        }
        else
          Protect(luaT_trybinTM(L, rb, rb, ra, TM_UNM));
        vmbreak;
      }
      vmcase(OP_BNOT) {
        TValue *rb = vRB(i);
        lua_Integer ib;
        if (tointegerns(rb, &ib)) {
          setivalue(s2v(ra), intop(^, ~l_castS2U(0), ib));
        }
        else
          Protect(luaT_trybinTM(L, rb, rb, ra, TM_BNOT));
        vmbreak;
      }
      vmcase(OP_NOT) {
        TValue *rb = vRB(i);
        if (l_isfalse(rb))
          setbtvalue(s2v(ra));
        else
          setbfvalue(s2v(ra));
        vmbreak;
      }
      vmcase(OP_LEN) {
        Protect(luaV_objlen(L, ra, vRB(i)));
        vmbreak;
      }
      vmcase(OP_CONCAT) {
        int n = GETARG_B(i);  /* number of elements to concatenate */
        L->top = ra + n;  /* mark the end of concat operands */
        ProtectNT(luaV_concat(L, n));
        checkGC(L, L->top); /* 'luaV_concat' ensures correct top */
        vmbreak;
      }
      vmcase(OP_CLOSE) {
        Protect(luaF_close(L, ra, LUA_OK));
        vmbreak;
      }
      vmcase(OP_TBC) {
        /* create new to-be-closed upvalue */
        halfProtect(luaF_newtbcupval(L, ra));
        vmbreak;
      }
      vmcase(OP_JMP) {
        dojump(ci, i, 0);
        vmbreak;
      }
      vmcase(OP_EQ) {
        int cond;
        TValue *rb = vRB(i);
        Protect(cond = luaV_equalobj(L, s2v(ra), rb));
        docondjump();
        vmbreak;
      }
      vmcase(OP_LT) {
        op_order(L, l_lti, LTnum, lessthanothers);
        vmbreak;
      }
      vmcase(OP_LE) {
        op_order(L, l_lei, LEnum, lessequalothers);
        vmbreak;
      }
      vmcase(OP_EQK) {
        TValue *rb = KB(i);
        /* basic types do not use '__eq'; we can use raw equality */
        int cond = luaV_rawequalobj(s2v(ra), rb);
        docondjump();
        vmbreak;
      }
      vmcase(OP_EQI) {
        int cond;
        int im = GETARG_sB(i);
        if (ttisinteger(s2v(ra)))
          cond = (ivalue(s2v(ra)) == im);
        else if (ttisfloat(s2v(ra)))
          cond = luai_numeq(fltvalue(s2v(ra)), cast_num(im));
        else
          cond = 0;  /* other types cannot be equal to a number */
        docondjump();
        vmbreak;
      }
      vmcase(OP_LTI) {
        op_orderI(L, l_lti, luai_numlt, 0, TM_LT);
        vmbreak;
      }
      vmcase(OP_LEI) {
        op_orderI(L, l_lei, luai_numle, 0, TM_LE);
        vmbreak;
      }
      vmcase(OP_GTI) {
        op_orderI(L, l_gti, luai_numgt, 1, TM_LT);
        vmbreak;
      }
      vmcase(OP_GEI) {
        op_orderI(L, l_gei, luai_numge, 1, TM_LE);
        vmbreak;
      }
      vmcase(OP_TEST) {
        int cond = !l_isfalse(s2v(ra));
        docondjump();
        vmbreak;
      }
      vmcase(OP_TESTSET) {
        TValue *rb = vRB(i);
        if (l_isfalse(rb) == GETARG_k(i))
          pc++;
        else {
          setobj2s(L, ra, rb);
          donextjump(ci);
        }
        vmbreak;
      }
      vmcase(OP_CALL) {
        int b = GETARG_B(i);
        int nresults = GETARG_C(i) - 1;
        if (b != 0)  /* fixed number of arguments? */
          L->top = ra + b;  /* top signals number of arguments */
        /* else previous instruction set top */
        ProtectNT(luaD_call(L, ra, nresults));
        vmbreak;
      }
      vmcase(OP_TAILCALL) {
        int b = GETARG_B(i);  /* number of arguments + 1 (function) */
        int nparams1 = GETARG_C(i);
        /* delat is virtual 'func' - real 'func' (vararg functions) */
        int delta = (nparams1) ? ci->u.l.nextraargs + nparams1 : 0;
        if (b != 0)
          L->top = ra + b;
        else  /* previous instruction set top */
          b = cast_int(L->top - ra);
        savepc(ci);  /* some calls here can raise errors */
        if (TESTARG_k(i)) {
          /* close upvalues from current call; the compiler ensures
             that there are no to-be-closed variables here, so this
             call cannot change the stack */
          luaF_close(L, base, NOCLOSINGMETH);
          lua_assert(base == ci->func + 1);
        }
        while (!ttisfunction(s2v(ra))) {  /* not a function? */
          luaD_tryfuncTM(L, ra);  /* try '__call' metamethod */
          b++;  /* there is now one extra argument */
          checkstackGCp(L, 1, ra);
        }
        if (!ttisLclosure(s2v(ra))) {  /* C function? */
          luaD_call(L, ra, LUA_MULTRET);  /* call it */
          updatetrap(ci);
          updatestack(ci);  /* stack may have been relocated */
          ci->func -= delta;
          luaD_poscall(L, ci, cast_int(L->top - ra));
          return;
        }
        ci->func -= delta;
        luaD_pretailcall(L, ci, ra, b);  /* prepare call frame */
        goto tailcall;
      }
      vmcase(OP_RETURN) {
        int n = GETARG_B(i) - 1;  /* number of results */
        int nparams1 = GETARG_C(i);
        if (n < 0)  /* not fixed? */
          n = cast_int(L->top - ra);  /* get what is available */
        savepc(ci);
        if (TESTARG_k(i)) {  /* may there be open upvalues? */
          if (L->top < ci->top)
            L->top = ci->top;
          luaF_close(L, base, LUA_OK);
          updatetrap(ci);
          updatestack(ci);
        }
        if (nparams1)  /* vararg function? */
          ci->func -= ci->u.l.nextraargs + nparams1;
        L->top = ra + n;  /* set call for 'luaD_poscall' */
        luaD_poscall(L, ci, n);
        return;
      }
      vmcase(OP_RETURN0) {
        if (L->hookmask) {
          L->top = ra;
          halfProtectNT(luaD_poscall(L, ci, 0));  /* no hurry... */
        }
        else {  /* do the 'poscall' here */
          int nres = ci->nresults;
          L->ci = ci->previous;  /* back to caller */
          L->top = base - 1;
          while (nres-- > 0)
            setnilvalue(s2v(L->top++));  /* all results are nil */
        }
        return;
      }
      vmcase(OP_RETURN1) {
        if (L->hookmask) {
          L->top = ra + 1;
          halfProtectNT(luaD_poscall(L, ci, 1));  /* no hurry... */
        }
        else {  /* do the 'poscall' here */
          int nres = ci->nresults;
          L->ci = ci->previous;  /* back to caller */
          if (nres == 0)
            L->top = base - 1;  /* asked for no results */
          else {
            setobjs2s(L, base - 1, ra);  /* at least this result */
            L->top = base;
            while (--nres > 0)  /* complete missing results */
              setnilvalue(s2v(L->top++));
          }
        }
        return;
      }
      vmcase(OP_FORLOOP) {
        if (ttisinteger(s2v(ra + 2))) {  /* integer loop? */
          lua_Unsigned count = l_castS2U(ivalue(s2v(ra + 1)));
          if (count > 0) {  /* still more iterations? */
            lua_Integer step = ivalue(s2v(ra + 2));
            lua_Integer idx = ivalue(s2v(ra));  /* internal index */
            chgivalue(s2v(ra + 1), count - 1);  /* update counter */
            idx = intop(+, idx, step);  /* add step to index */
            chgivalue(s2v(ra), idx);  /* update internal index */
            setivalue(s2v(ra + 3), idx);  /* and control variable */
            pc -= GETARG_Bx(i);  /* jump back */
          }
        }
        else if (floatforloop(ra))  /* float loop */
          pc -= GETARG_Bx(i);  /* jump back */
        updatetrap(ci);  /* allows a signal to break the loop */
        vmbreak;
      }
      vmcase(OP_FORPREP) {
        savestate(L, ci);  /* in case of errors */
        if (forprep(L, ra))
          pc += GETARG_Bx(i) + 1;  /* skip the loop */
        vmbreak;
      }
      vmcase(OP_TFORPREP) {
        /* create to-be-closed upvalue (if needed) */
        halfProtect(luaF_newtbcupval(L, ra + 3));
        pc += GETARG_Bx(i);
        i = *(pc++);  /* go to next instruction */
        lua_assert(GET_OPCODE(i) == OP_TFORCALL && ra == RA(i));
        goto l_tforcall;
      }
      vmcase(OP_TFORCALL) {
       l_tforcall:
        /* 'ra' has the iterator function, 'ra + 1' has the state,
           'ra + 2' has the control variable, and 'ra + 3' has the
           to-be-closed variable. The call will use the stack after
           these values (starting at 'ra + 4')
        */
        /* push function, state, and control variable */
        memcpy(ra + 4, ra, 3 * sizeof(*ra));
        L->top = ra + 4 + 3;
        ProtectNT(luaD_call(L, ra + 4, GETARG_C(i)));  /* do the call */
        updatestack(ci);  /* stack may have changed */
        i = *(pc++);  /* go to next instruction */
        lua_assert(GET_OPCODE(i) == OP_TFORLOOP && ra == RA(i));
        goto l_tforloop;
      }
      vmcase(OP_TFORLOOP) {
        l_tforloop:
        if (!ttisnil(s2v(ra + 4))) {  /* continue loop? */
          setobjs2s(L, ra + 2, ra + 4);  /* save control variable */
          pc -= GETARG_Bx(i);  /* jump back */
        }
        vmbreak;
      }
      vmcase(OP_SETLIST) {
        int n = GETARG_B(i);
        unsigned int last = GETARG_C(i);
        Table *h = hvalue(s2v(ra));
        if (n == 0)
          n = cast_int(L->top - ra) - 1;  /* get up to the top */
        else
          L->top = ci->top;  /* correct top in case of emergency GC */
        last += n;
        if (TESTARG_k(i)) {
          last += GETARG_Ax(*pc) * (MAXARG_C + 1);
          pc++;
        }
        if (last > luaH_realasize(h))  /* needs more space? */
          luaH_resizearray(L, h, last);  /* preallocate it at once */
        for (; n > 0; n--) {
          TValue *val = s2v(ra + n);
          setobj2t(L, &h->array[last - 1], val);
          last--;
          luaC_barrierback(L, obj2gco(h), val);
        }
        vmbreak;
      }
      vmcase(OP_CLOSURE) {
        Proto *p = cl->p->p[GETARG_Bx(i)];
        halfProtect(pushclosure(L, p, cl->upvals, base, ra));
        checkGC(L, ra + 1);
        vmbreak;
      }
      vmcase(OP_VARARG) {
        int n = GETARG_C(i) - 1;  /* required results */
        Protect(luaT_getvarargs(L, ci, ra, n));
        vmbreak;
      }
      vmcase(OP_VARARGPREP) {
        ProtectNT(luaT_adjustvarargs(L, GETARG_A(i), ci, cl->p));
        if (trap) {
          luaD_hookcall(L, ci);
          L->oldpc = 1;  /* next opcode will be seen as a "new" line */
        }
        updatebase(ci);  /* function has new base after adjustment */
        vmbreak;
      }
      vmcase(OP_EXTRAARG) {
        lua_assert(0);
        vmbreak;
      }
    }
  }
}

Project: lua

static void f_luaopen (lua_State *L, void *ud) {
  global_State *g = G(L);
  UNUSED(ud);
  stack_init(L, L);  /* init stack */
  init_registry(L, g);
  luaS_init(L);
  luaT_init(L);
  luaX_init(L);
  g->gcrunning = 1;  /* allow gc */
  setnilvalue(&g->nilvalue);
  luai_userstateopen(L);
}

Project: lua

static void close_state (lua_State *L) {
  global_State *g = G(L);
  luaF_close(L, L->stack, CLOSEPROTECT);  /* close all upvalues */
  luaC_freeallobjects(L);  /* collect all objects */
  if (ttisnil(&g->nilvalue))  /* closing a fully built state? */
    luai_userstateclose(L);
  luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
  freestack(L);
  lua_assert(gettotalbytes(g) == sizeof(LG));
  (*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0);  /* free main block */
}

Project: lua

void luaE_freethread (lua_State *L, lua_State *L1) {
  LX *l = fromstate(L1);
  luaF_close(L1, L1->stack, NOCLOSINGMETH);  /* close all upvalues */
  lua_assert(L1->openupval == NULL);
  luai_userstatefree(L, L1);
  freestack(L1);
  luaM_free(L, l);
}

Project: lua

static void stack_init (lua_State *L1, lua_State *L) {
  int i; CallInfo *ci;
  /* initialize stack array */
  L1->stack = luaM_newvector(L, BASIC_STACK_SIZE, StackValue);
  L1->stacksize = BASIC_STACK_SIZE;
  for (i = 0; i < BASIC_STACK_SIZE; i++)
    setnilvalue(s2v(L1->stack + i));  /* erase new stack */
  L1->top = L1->stack;
  L1->stack_last = L1->stack + L1->stacksize - EXTRA_STACK;
  /* initialize first ci */
  ci = &L1->base_ci;
  ci->next = ci->previous = NULL;
  ci->callstatus = CIST_C;
  ci->func = L1->top;
  ci->u.c.k = NULL;
  ci->nresults = 0;
  setnilvalue(s2v(L1->top));  /* 'function' entry for this 'ci' */
  L1->top++;
  ci->top = L1->top + LUA_MINSTACK;
  L1->ci = ci;
}

Project: lua

void luaE_warnerror (lua_State *L, const char *where) {
  TValue *errobj = s2v(L->top - 1);  /* error object */
  const char *msg = (ttisstring(errobj))
                  ? svalue(errobj)
                  : "error object is not a string";
  /* produce warning "error in %s (%s)" (where, msg) */
  luaE_warning(L, "error in ", 1);
  luaE_warning(L, where, 1);
  luaE_warning(L, " (", 1);
  luaE_warning(L, msg, 1);
  luaE_warning(L, ")", 0);
}

Project: lua

void luaE_shrinkCI (lua_State *L) {
  CallInfo *ci = L->ci->next;  /* first free CallInfo */
  CallInfo *next;
  if (ci == NULL)
    return;  /* no extra elements */
  L->nCcalls += L->nci;  /* add removed elements back to 'nCcalls' */
  while ((next = ci->next) != NULL) {  /* two extra elements? */
    CallInfo *next2 = next->next;  /* next's next */
    ci->next = next2;  /* remove next from the list */
    L->nci--;
    luaM_free(L, next);  /* free next */
    if (next2 == NULL)
      break;  /* no more elements */
    else {
      next2->previous = ci;
      ci = next2;  /* continue */
    }
  }
  L->nCcalls -= L->nci;  /* adjust result */
}

Project: lua

static unsigned int luai_makeseed (lua_State *L) {
  char buff[3 * sizeof(size_t)];
  unsigned int h = cast_uint(time(NULL));
  int p = 0;
  addbuff(buff, p, L);  /* heap variable */
  addbuff(buff, p, &h);  /* local variable */
  addbuff(buff, p, &lua_newstate);  /* public function */
  lua_assert(p == sizeof(buff));
  return luaS_hash(buff, p, h, 1);
}

Project: lua

LUA_API int lua_setcstacklimit (lua_State *L, unsigned int limit) {
  global_State *g = G(L);
  int ccalls;
  luaE_freeCI(L);  /* release unused CIs */
  ccalls = getCcalls(L);
  if (limit >= 40000)
    return 0;  /* out of bounds */
  limit += CSTACKERR;
  if (L != g-> mainthread)
    return 0;  /* only main thread can change the C stack */
  else if (ccalls <= CSTACKERR)
    return 0;  /* handling overflow */
  else {
    int diff = limit - g->Cstacklimit;
    if (ccalls + diff <= CSTACKERR)
      return 0;  /* new limit would cause an overflow */
    g->Cstacklimit = limit;  /* set new limit */
    L->nCcalls += diff;  /* correct 'nCcalls' */
    return limit - diff - CSTACKERR;  /* success; return previous limit */
  }
}

Project: lua

static void preinit_thread (lua_State *L, global_State *g) {
  G(L) = g;
  L->stack = NULL;
  L->ci = NULL;
  L->nci = 0;
  L->stacksize = 0;
  L->twups = L;  /* thread has no upvalues */
  L->errorJmp = NULL;
  L->hook = NULL;
  L->hookmask = 0;
  L->basehookcount = 0;
  L->allowhook = 1;
  resethookcount(L);
  L->openupval = NULL;
  L->status = LUA_OK;
  L->errfunc = 0;
  L->oldpc = 0;
}

Project: lua

void luaE_warning (lua_State *L, const char *msg, int tocont) {
  lua_WarnFunction wf = G(L)->warnf;
  if (wf != NULL)
    wf(G(L)->ud_warn, msg, tocont);
}