rlm@1: /*
rlm@1: ** $Id: ldebug.c,v 2.29.1.6 2008/05/08 16:56:26 roberto Exp $
rlm@1: ** Debug Interface
rlm@1: ** See Copyright Notice in lua.h
rlm@1: */
rlm@1: 
rlm@1: 
rlm@1: #include <stdarg.h>
rlm@1: #include <stddef.h>
rlm@1: #include <string.h>
rlm@1: 
rlm@1: 
rlm@1: #define ldebug_c
rlm@1: #define LUA_CORE
rlm@1: 
rlm@1: #include "lua.h"
rlm@1: 
rlm@1: #include "lapi.h"
rlm@1: #include "lcode.h"
rlm@1: #include "ldebug.h"
rlm@1: #include "ldo.h"
rlm@1: #include "lfunc.h"
rlm@1: #include "lobject.h"
rlm@1: #include "lopcodes.h"
rlm@1: #include "lstate.h"
rlm@1: #include "lstring.h"
rlm@1: #include "ltable.h"
rlm@1: #include "ltm.h"
rlm@1: #include "lvm.h"
rlm@1: 
rlm@1: 
rlm@1: 
rlm@1: static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name);
rlm@1: 
rlm@1: 
rlm@1: static int currentpc (lua_State *L, CallInfo *ci) {
rlm@1:   if (!isLua(ci)) return -1;  /* function is not a Lua function? */
rlm@1:   if (ci == L->ci)
rlm@1:     ci->savedpc = L->savedpc;
rlm@1:   return pcRel(ci->savedpc, ci_func(ci)->l.p);
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static int currentline (lua_State *L, CallInfo *ci) {
rlm@1:   int pc = currentpc(L, ci);
rlm@1:   if (pc < 0)
rlm@1:     return -1;  /* only active lua functions have current-line information */
rlm@1:   else
rlm@1:     return getline(ci_func(ci)->l.p, pc);
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: /*
rlm@1: ** this function can be called asynchronous (e.g. during a signal)
rlm@1: */
rlm@1: LUA_API int lua_sethook (lua_State *L, lua_Hook func, int mask, int count) {
rlm@1:   if (func == NULL || mask == 0) {  /* turn off hooks? */
rlm@1:     mask = 0;
rlm@1:     func = NULL;
rlm@1:   }
rlm@1:   L->hook = func;
rlm@1:   L->basehookcount = count;
rlm@1:   resethookcount(L);
rlm@1:   L->hookmask = cast_byte(mask);
rlm@1:   return 1;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: LUA_API lua_Hook lua_gethook (lua_State *L) {
rlm@1:   return L->hook;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: LUA_API int lua_gethookmask (lua_State *L) {
rlm@1:   return L->hookmask;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: LUA_API int lua_gethookcount (lua_State *L) {
rlm@1:   return L->basehookcount;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: LUA_API int lua_getstack (lua_State *L, int level, lua_Debug *ar) {
rlm@1:   int status;
rlm@1:   CallInfo *ci;
rlm@1:   lua_lock(L);
rlm@1:   for (ci = L->ci; level > 0 && ci > L->base_ci; ci--) {
rlm@1:     level--;
rlm@1:     if (f_isLua(ci))  /* Lua function? */
rlm@1:       level -= ci->tailcalls;  /* skip lost tail calls */
rlm@1:   }
rlm@1:   if (level == 0 && ci > L->base_ci) {  /* level found? */
rlm@1:     status = 1;
rlm@1:     ar->i_ci = cast_int(ci - L->base_ci);
rlm@1:   }
rlm@1:   else if (level < 0) {  /* level is of a lost tail call? */
rlm@1:     status = 1;
rlm@1:     ar->i_ci = 0;
rlm@1:   }
rlm@1:   else status = 0;  /* no such level */
rlm@1:   lua_unlock(L);
rlm@1:   return status;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static Proto *getluaproto (CallInfo *ci) {
rlm@1:   return (isLua(ci) ? ci_func(ci)->l.p : NULL);
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static const char *findlocal (lua_State *L, CallInfo *ci, int n) {
rlm@1:   const char *name;
rlm@1:   Proto *fp = getluaproto(ci);
rlm@1:   if (fp && (name = luaF_getlocalname(fp, n, currentpc(L, ci))) != NULL)
rlm@1:     return name;  /* is a local variable in a Lua function */
rlm@1:   else {
rlm@1:     StkId limit = (ci == L->ci) ? L->top : (ci+1)->func;
rlm@1:     if (limit - ci->base >= n && n > 0)  /* is 'n' inside 'ci' stack? */
rlm@1:       return "(*temporary)";
rlm@1:     else
rlm@1:       return NULL;
rlm@1:   }
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: LUA_API const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n) {
rlm@1:   CallInfo *ci = L->base_ci + ar->i_ci;
rlm@1:   const char *name = findlocal(L, ci, n);
rlm@1:   lua_lock(L);
rlm@1:   if (name)
rlm@1:       luaA_pushobject(L, ci->base + (n - 1));
rlm@1:   lua_unlock(L);
rlm@1:   return name;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: LUA_API const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n) {
rlm@1:   CallInfo *ci = L->base_ci + ar->i_ci;
rlm@1:   const char *name = findlocal(L, ci, n);
rlm@1:   lua_lock(L);
rlm@1:   if (name)
rlm@1:       setobjs2s(L, ci->base + (n - 1), L->top - 1);
rlm@1:   L->top--;  /* pop value */
rlm@1:   lua_unlock(L);
rlm@1:   return name;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static void funcinfo (lua_Debug *ar, Closure *cl) {
rlm@1:   if (cl->c.isC) {
rlm@1:     ar->source = "=[C]";
rlm@1:     ar->linedefined = -1;
rlm@1:     ar->lastlinedefined = -1;
rlm@1:     ar->what = "C";
rlm@1:   }
rlm@1:   else {
rlm@1:     ar->source = getstr(cl->l.p->source);
rlm@1:     ar->linedefined = cl->l.p->linedefined;
rlm@1:     ar->lastlinedefined = cl->l.p->lastlinedefined;
rlm@1:     ar->what = (ar->linedefined == 0) ? "main" : "Lua";
rlm@1:   }
rlm@1:   luaO_chunkid(ar->short_src, ar->source, LUA_IDSIZE);
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static void info_tailcall (lua_Debug *ar) {
rlm@1:   ar->name = ar->namewhat = "";
rlm@1:   ar->what = "tail";
rlm@1:   ar->lastlinedefined = ar->linedefined = ar->currentline = -1;
rlm@1:   ar->source = "=(tail call)";
rlm@1:   luaO_chunkid(ar->short_src, ar->source, LUA_IDSIZE);
rlm@1:   ar->nups = 0;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static void collectvalidlines (lua_State *L, Closure *f) {
rlm@1:   if (f == NULL || f->c.isC) {
rlm@1:     setnilvalue(L->top);
rlm@1:   }
rlm@1:   else {
rlm@1:     Table *t = luaH_new(L, 0, 0);
rlm@1:     int *lineinfo = f->l.p->lineinfo;
rlm@1:     int i;
rlm@1:     for (i=0; i<f->l.p->sizelineinfo; i++)
rlm@1:       setbvalue(luaH_setnum(L, t, lineinfo[i]), 1);
rlm@1:     sethvalue(L, L->top, t); 
rlm@1:   }
rlm@1:   incr_top(L);
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static int auxgetinfo (lua_State *L, const char *what, lua_Debug *ar,
rlm@1:                     Closure *f, CallInfo *ci) {
rlm@1:   int status = 1;
rlm@1:   if (f == NULL) {
rlm@1:     info_tailcall(ar);
rlm@1:     return status;
rlm@1:   }
rlm@1:   for (; *what; what++) {
rlm@1:     switch (*what) {
rlm@1:       case 'S': {
rlm@1:         funcinfo(ar, f);
rlm@1:         break;
rlm@1:       }
rlm@1:       case 'l': {
rlm@1:         ar->currentline = (ci) ? currentline(L, ci) : -1;
rlm@1:         break;
rlm@1:       }
rlm@1:       case 'u': {
rlm@1:         ar->nups = f->c.nupvalues;
rlm@1:         break;
rlm@1:       }
rlm@1:       case 'n': {
rlm@1:         ar->namewhat = (ci) ? getfuncname(L, ci, &ar->name) : NULL;
rlm@1:         if (ar->namewhat == NULL) {
rlm@1:           ar->namewhat = "";  /* not found */
rlm@1:           ar->name = NULL;
rlm@1:         }
rlm@1:         break;
rlm@1:       }
rlm@1:       case 'L':
rlm@1:       case 'f':  /* handled by lua_getinfo */
rlm@1:         break;
rlm@1:       default: status = 0;  /* invalid option */
rlm@1:     }
rlm@1:   }
rlm@1:   return status;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: LUA_API int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
rlm@1:   int status;
rlm@1:   Closure *f = NULL;
rlm@1:   CallInfo *ci = NULL;
rlm@1:   lua_lock(L);
rlm@1:   if (*what == '>') {
rlm@1:     StkId func = L->top - 1;
rlm@1:     luai_apicheck(L, ttisfunction(func));
rlm@1:     what++;  /* skip the '>' */
rlm@1:     f = clvalue(func);
rlm@1:     L->top--;  /* pop function */
rlm@1:   }
rlm@1:   else if (ar->i_ci != 0) {  /* no tail call? */
rlm@1:     ci = L->base_ci + ar->i_ci;
rlm@1:     lua_assert(ttisfunction(ci->func));
rlm@1:     f = clvalue(ci->func);
rlm@1:   }
rlm@1:   status = auxgetinfo(L, what, ar, f, ci);
rlm@1:   if (strchr(what, 'f')) {
rlm@1:     if (f == NULL) setnilvalue(L->top);
rlm@1:     else setclvalue(L, L->top, f);
rlm@1:     incr_top(L);
rlm@1:   }
rlm@1:   if (strchr(what, 'L'))
rlm@1:     collectvalidlines(L, f);
rlm@1:   lua_unlock(L);
rlm@1:   return status;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: /*
rlm@1: ** {======================================================
rlm@1: ** Symbolic Execution and code checker
rlm@1: ** =======================================================
rlm@1: */
rlm@1: 
rlm@1: #define check(x)		if (!(x)) return 0;
rlm@1: 
rlm@1: #define checkjump(pt,pc)	check(0 <= pc && pc < pt->sizecode)
rlm@1: 
rlm@1: #define checkreg(pt,reg)	check((reg) < (pt)->maxstacksize)
rlm@1: 
rlm@1: 
rlm@1: 
rlm@1: static int precheck (const Proto *pt) {
rlm@1:   check(pt->maxstacksize <= MAXSTACK);
rlm@1:   check(pt->numparams+(pt->is_vararg & VARARG_HASARG) <= pt->maxstacksize);
rlm@1:   check(!(pt->is_vararg & VARARG_NEEDSARG) ||
rlm@1:               (pt->is_vararg & VARARG_HASARG));
rlm@1:   check(pt->sizeupvalues <= pt->nups);
rlm@1:   check(pt->sizelineinfo == pt->sizecode || pt->sizelineinfo == 0);
rlm@1:   check(pt->sizecode > 0 && GET_OPCODE(pt->code[pt->sizecode-1]) == OP_RETURN);
rlm@1:   return 1;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: #define checkopenop(pt,pc)	luaG_checkopenop((pt)->code[(pc)+1])
rlm@1: 
rlm@1: int luaG_checkopenop (Instruction i) {
rlm@1:   switch (GET_OPCODE(i)) {
rlm@1:     case OP_CALL:
rlm@1:     case OP_TAILCALL:
rlm@1:     case OP_RETURN:
rlm@1:     case OP_SETLIST: {
rlm@1:       check(GETARG_B(i) == 0);
rlm@1:       return 1;
rlm@1:     }
rlm@1:     default: return 0;  /* invalid instruction after an open call */
rlm@1:   }
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static int checkArgMode (const Proto *pt, int r, enum OpArgMask mode) {
rlm@1:   switch (mode) {
rlm@1:     case OpArgN: check(r == 0); break;
rlm@1:     case OpArgU: break;
rlm@1:     case OpArgR: checkreg(pt, r); break;
rlm@1:     case OpArgK:
rlm@1:       check(ISK(r) ? INDEXK(r) < pt->sizek : r < pt->maxstacksize);
rlm@1:       break;
rlm@1:   }
rlm@1:   return 1;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static Instruction symbexec (const Proto *pt, int lastpc, int reg) {
rlm@1:   int pc;
rlm@1:   int last;  /* stores position of last instruction that changed `reg' */
rlm@1:   last = pt->sizecode-1;  /* points to final return (a `neutral' instruction) */
rlm@1:   check(precheck(pt));
rlm@1:   for (pc = 0; pc < lastpc; pc++) {
rlm@1:     Instruction i = pt->code[pc];
rlm@1:     OpCode op = GET_OPCODE(i);
rlm@1:     int a = GETARG_A(i);
rlm@1:     int b = 0;
rlm@1:     int c = 0;
rlm@1:     check(op < NUM_OPCODES);
rlm@1:     checkreg(pt, a);
rlm@1:     switch (getOpMode(op)) {
rlm@1:       case iABC: {
rlm@1:         b = GETARG_B(i);
rlm@1:         c = GETARG_C(i);
rlm@1:         check(checkArgMode(pt, b, getBMode(op)));
rlm@1:         check(checkArgMode(pt, c, getCMode(op)));
rlm@1:         break;
rlm@1:       }
rlm@1:       case iABx: {
rlm@1:         b = GETARG_Bx(i);
rlm@1:         if (getBMode(op) == OpArgK) check(b < pt->sizek);
rlm@1:         break;
rlm@1:       }
rlm@1:       case iAsBx: {
rlm@1:         b = GETARG_sBx(i);
rlm@1:         if (getBMode(op) == OpArgR) {
rlm@1:           int dest = pc+1+b;
rlm@1:           check(0 <= dest && dest < pt->sizecode);
rlm@1:           if (dest > 0) {
rlm@1:             int j;
rlm@1:             /* check that it does not jump to a setlist count; this
rlm@1:                is tricky, because the count from a previous setlist may
rlm@1:                have the same value of an invalid setlist; so, we must
rlm@1:                go all the way back to the first of them (if any) */
rlm@1:             for (j = 0; j < dest; j++) {
rlm@1:               Instruction d = pt->code[dest-1-j];
rlm@1:               if (!(GET_OPCODE(d) == OP_SETLIST && GETARG_C(d) == 0)) break;
rlm@1:             }
rlm@1:             /* if 'j' is even, previous value is not a setlist (even if
rlm@1:                it looks like one) */
rlm@1:             check((j&1) == 0);
rlm@1:           }
rlm@1:         }
rlm@1:         break;
rlm@1:       }
rlm@1:     }
rlm@1:     if (testAMode(op)) {
rlm@1:       if (a == reg) last = pc;  /* change register `a' */
rlm@1:     }
rlm@1:     if (testTMode(op)) {
rlm@1:       check(pc+2 < pt->sizecode);  /* check skip */
rlm@1:       check(GET_OPCODE(pt->code[pc+1]) == OP_JMP);
rlm@1:     }
rlm@1:     switch (op) {
rlm@1:       case OP_LOADBOOL: {
rlm@1:         if (c == 1) {  /* does it jump? */
rlm@1:           check(pc+2 < pt->sizecode);  /* check its jump */
rlm@1:           check(GET_OPCODE(pt->code[pc+1]) != OP_SETLIST ||
rlm@1:                 GETARG_C(pt->code[pc+1]) != 0);
rlm@1:         }
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_LOADNIL: {
rlm@1:         if (a <= reg && reg <= b)
rlm@1:           last = pc;  /* set registers from `a' to `b' */
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_GETUPVAL:
rlm@1:       case OP_SETUPVAL: {
rlm@1:         check(b < pt->nups);
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_GETGLOBAL:
rlm@1:       case OP_SETGLOBAL: {
rlm@1:         check(ttisstring(&pt->k[b]));
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_SELF: {
rlm@1:         checkreg(pt, a+1);
rlm@1:         if (reg == a+1) last = pc;
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_CONCAT: {
rlm@1:         check(b < c);  /* at least two operands */
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_TFORLOOP: {
rlm@1:         check(c >= 1);  /* at least one result (control variable) */
rlm@1:         checkreg(pt, a+2+c);  /* space for results */
rlm@1:         if (reg >= a+2) last = pc;  /* affect all regs above its base */
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_FORLOOP:
rlm@1:       case OP_FORPREP:
rlm@1:         checkreg(pt, a+3);
rlm@1:         /* go through */
rlm@1:       case OP_JMP: {
rlm@1:         int dest = pc+1+b;
rlm@1:         /* not full check and jump is forward and do not skip `lastpc'? */
rlm@1:         if (reg != NO_REG && pc < dest && dest <= lastpc)
rlm@1:           pc += b;  /* do the jump */
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_CALL:
rlm@1:       case OP_TAILCALL: {
rlm@1:         if (b != 0) {
rlm@1:           checkreg(pt, a+b-1);
rlm@1:         }
rlm@1:         c--;  /* c = num. returns */
rlm@1:         if (c == LUA_MULTRET) {
rlm@1:           check(checkopenop(pt, pc));
rlm@1:         }
rlm@1:         else if (c != 0)
rlm@1:           checkreg(pt, a+c-1);
rlm@1:         if (reg >= a) last = pc;  /* affect all registers above base */
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_RETURN: {
rlm@1:         b--;  /* b = num. returns */
rlm@1:         if (b > 0) checkreg(pt, a+b-1);
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_SETLIST: {
rlm@1:         if (b > 0) checkreg(pt, a + b);
rlm@1:         if (c == 0) {
rlm@1:           pc++;
rlm@1:           check(pc < pt->sizecode - 1);
rlm@1:         }
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_CLOSURE: {
rlm@1:         int nup, j;
rlm@1:         check(b < pt->sizep);
rlm@1:         nup = pt->p[b]->nups;
rlm@1:         check(pc + nup < pt->sizecode);
rlm@1:         for (j = 1; j <= nup; j++) {
rlm@1:           OpCode op1 = GET_OPCODE(pt->code[pc + j]);
rlm@1:           check(op1 == OP_GETUPVAL || op1 == OP_MOVE);
rlm@1:         }
rlm@1:         if (reg != NO_REG)  /* tracing? */
rlm@1:           pc += nup;  /* do not 'execute' these pseudo-instructions */
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_VARARG: {
rlm@1:         check((pt->is_vararg & VARARG_ISVARARG) &&
rlm@1:              !(pt->is_vararg & VARARG_NEEDSARG));
rlm@1:         b--;
rlm@1:         if (b == LUA_MULTRET) check(checkopenop(pt, pc));
rlm@1:         checkreg(pt, a+b-1);
rlm@1:         break;
rlm@1:       }
rlm@1:       default: break;
rlm@1:     }
rlm@1:   }
rlm@1:   return pt->code[last];
rlm@1: }
rlm@1: 
rlm@1: #undef check
rlm@1: #undef checkjump
rlm@1: #undef checkreg
rlm@1: 
rlm@1: /* }====================================================== */
rlm@1: 
rlm@1: 
rlm@1: int luaG_checkcode (const Proto *pt) {
rlm@1:   return (symbexec(pt, pt->sizecode, NO_REG) != 0);
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static const char *kname (Proto *p, int c) {
rlm@1:   if (ISK(c) && ttisstring(&p->k[INDEXK(c)]))
rlm@1:     return svalue(&p->k[INDEXK(c)]);
rlm@1:   else
rlm@1:     return "?";
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static const char *getobjname (lua_State *L, CallInfo *ci, int stackpos,
rlm@1:                                const char **name) {
rlm@1:   if (isLua(ci)) {  /* a Lua function? */
rlm@1:     Proto *p = ci_func(ci)->l.p;
rlm@1:     int pc = currentpc(L, ci);
rlm@1:     Instruction i;
rlm@1:     *name = luaF_getlocalname(p, stackpos+1, pc);
rlm@1:     if (*name)  /* is a local? */
rlm@1:       return "local";
rlm@1:     i = symbexec(p, pc, stackpos);  /* try symbolic execution */
rlm@1:     lua_assert(pc != -1);
rlm@1:     switch (GET_OPCODE(i)) {
rlm@1:       case OP_GETGLOBAL: {
rlm@1:         int g = GETARG_Bx(i);  /* global index */
rlm@1:         lua_assert(ttisstring(&p->k[g]));
rlm@1:         *name = svalue(&p->k[g]);
rlm@1:         return "global";
rlm@1:       }
rlm@1:       case OP_MOVE: {
rlm@1:         int a = GETARG_A(i);
rlm@1:         int b = GETARG_B(i);  /* move from `b' to `a' */
rlm@1:         if (b < a)
rlm@1:           return getobjname(L, ci, b, name);  /* get name for `b' */
rlm@1:         break;
rlm@1:       }
rlm@1:       case OP_GETTABLE: {
rlm@1:         int k = GETARG_C(i);  /* key index */
rlm@1:         *name = kname(p, k);
rlm@1:         return "field";
rlm@1:       }
rlm@1:       case OP_GETUPVAL: {
rlm@1:         int u = GETARG_B(i);  /* upvalue index */
rlm@1:         *name = p->upvalues ? getstr(p->upvalues[u]) : "?";
rlm@1:         return "upvalue";
rlm@1:       }
rlm@1:       case OP_SELF: {
rlm@1:         int k = GETARG_C(i);  /* key index */
rlm@1:         *name = kname(p, k);
rlm@1:         return "method";
rlm@1:       }
rlm@1:       default: break;
rlm@1:     }
rlm@1:   }
rlm@1:   return NULL;  /* no useful name found */
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
rlm@1:   Instruction i;
rlm@1:   if ((isLua(ci) && ci->tailcalls > 0) || !isLua(ci - 1))
rlm@1:     return NULL;  /* calling function is not Lua (or is unknown) */
rlm@1:   ci--;  /* calling function */
rlm@1:   i = ci_func(ci)->l.p->code[currentpc(L, ci)];
rlm@1:   if (GET_OPCODE(i) == OP_CALL || GET_OPCODE(i) == OP_TAILCALL ||
rlm@1:       GET_OPCODE(i) == OP_TFORLOOP)
rlm@1:     return getobjname(L, ci, GETARG_A(i), name);
rlm@1:   else
rlm@1:     return NULL;  /* no useful name can be found */
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: /* only ANSI way to check whether a pointer points to an array */
rlm@1: static int isinstack (CallInfo *ci, const TValue *o) {
rlm@1:   StkId p;
rlm@1:   for (p = ci->base; p < ci->top; p++)
rlm@1:     if (o == p) return 1;
rlm@1:   return 0;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: void luaG_typeerror (lua_State *L, const TValue *o, const char *op) {
rlm@1:   const char *name = NULL;
rlm@1:   const char *t = luaT_typenames[ttype(o)];
rlm@1:   const char *kind = (isinstack(L->ci, o)) ?
rlm@1:                          getobjname(L, L->ci, cast_int(o - L->base), &name) :
rlm@1:                          NULL;
rlm@1:   if (kind)
rlm@1:     luaG_runerror(L, "attempt to %s %s " LUA_QS " (a %s value)",
rlm@1:                 op, kind, name, t);
rlm@1:   else
rlm@1:     luaG_runerror(L, "attempt to %s a %s value", op, t);
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: void luaG_concaterror (lua_State *L, StkId p1, StkId p2) {
rlm@1:   if (ttisstring(p1) || ttisnumber(p1)) p1 = p2;
rlm@1:   lua_assert(!ttisstring(p1) && !ttisnumber(p1));
rlm@1:   luaG_typeerror(L, p1, "concatenate");
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: void luaG_aritherror (lua_State *L, const TValue *p1, const TValue *p2) {
rlm@1:   TValue temp;
rlm@1:   if (luaV_tonumber(p1, &temp) == NULL)
rlm@1:     p2 = p1;  /* first operand is wrong */
rlm@1:   luaG_typeerror(L, p2, "perform arithmetic on");
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: int luaG_ordererror (lua_State *L, const TValue *p1, const TValue *p2) {
rlm@1:   const char *t1 = luaT_typenames[ttype(p1)];
rlm@1:   const char *t2 = luaT_typenames[ttype(p2)];
rlm@1:   if (t1[2] == t2[2])
rlm@1:     luaG_runerror(L, "attempt to compare two %s values", t1);
rlm@1:   else
rlm@1:     luaG_runerror(L, "attempt to compare %s with %s", t1, t2);
rlm@1:   return 0;
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: static void addinfo (lua_State *L, const char *msg) {
rlm@1:   CallInfo *ci = L->ci;
rlm@1:   if (isLua(ci)) {  /* is Lua code? */
rlm@1:     char buff[LUA_IDSIZE];  /* add file:line information */
rlm@1:     int line = currentline(L, ci);
rlm@1:     luaO_chunkid(buff, getstr(getluaproto(ci)->source), LUA_IDSIZE);
rlm@1:     luaO_pushfstring(L, "%s:%d: %s", buff, line, msg);
rlm@1:   }
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: void luaG_errormsg (lua_State *L) {
rlm@1:   if (L->errfunc != 0) {  /* is there an error handling function? */
rlm@1:     StkId errfunc = restorestack(L, L->errfunc);
rlm@1:     if (!ttisfunction(errfunc)) luaD_throw(L, LUA_ERRERR);
rlm@1:     setobjs2s(L, L->top, L->top - 1);  /* move argument */
rlm@1:     setobjs2s(L, L->top - 1, errfunc);  /* push function */
rlm@1:     incr_top(L);
rlm@1:     luaD_call(L, L->top - 2, 1);  /* call it */
rlm@1:   }
rlm@1:   luaD_throw(L, LUA_ERRRUN);
rlm@1: }
rlm@1: 
rlm@1: 
rlm@1: void luaG_runerror (lua_State *L, const char *fmt, ...) {
rlm@1:   va_list argp;
rlm@1:   va_start(argp, fmt);
rlm@1:   addinfo(L, luaO_pushvfstring(L, fmt, argp));
rlm@1:   va_end(argp);
rlm@1:   luaG_errormsg(L);
rlm@1: }
rlm@1: