lua/ldebug.c

/*
** $Id: ldebug.c,v 1.109 2002/04/22 14:40:23 roberto Exp roberto $
** Debug Interface
** See Copyright Notice in lua.h
*/


#include <stdlib.h>

#include "lua.h"

#include "lapi.h"
#include "lcode.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "luadebug.h"
#include "lvm.h"



static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name);



static int isLmark (CallInfo *ci) {
  return (ttype(ci->base - 1) == LUA_TFUNCTION && !ci_func(ci)->c.isC);
}


static int currentpc (lua_State *L, CallInfo *ci) {
  if (ci->pc == NULL) return -1;  /* function is not an active Lua function */
  if (ci == L->ci || ci->pc != (ci+1)->pc)  /* no other function using `pc'? */
    ci->savedpc = *ci->pc;  /* may not be saved; save it */
  /* function's pc is saved */
  return pcRel(ci->savedpc, ci_func(ci)->l.p);
}


static int currentline (lua_State *L, CallInfo *ci) {
  int pc = currentpc(L, ci);
  if (pc < 0)
    return -1;  /* only active lua functions have current-line information */
  else
    return ci_func(ci)->l.p->lineinfo[pc];
}


LUA_API lua_Hook lua_setcallhook (lua_State *L, lua_Hook func) {
  lua_Hook oldhook;
  lua_lock(L);
  oldhook = L->callhook;
  L->callhook = func;
  lua_unlock(L);
  return oldhook;
}


LUA_API lua_Hook lua_setlinehook (lua_State *L, lua_Hook func) {
  CallInfo *ci;
  lua_Hook oldhook;
  lua_lock(L);
  oldhook = L->linehook;
  L->linehook = func;
  for (ci = L->base_ci; ci <= L->ci; ci++)
    currentpc(L, ci);  /* update `savedpc' */
  lua_unlock(L);
  return oldhook;
}


LUA_API int lua_getstack (lua_State *L, int level, lua_Debug *ar) {
  int status;
  lua_lock(L);
  if (L->ci - L->base_ci <= level) status = 0;  /* there is no such level */
  else {
    ar->i_ci = (L->ci - L->base_ci) - level;
    status = 1;
  }
  lua_unlock(L);
  return status;
}


static Proto *getluaproto (CallInfo *ci) {
  return (isLmark(ci) ? ci_func(ci)->l.p : NULL);
}


LUA_API const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n) {
  const char *name;
  CallInfo *ci;
  Proto *fp;
  lua_lock(L);
  name = NULL;
  ci = L->base_ci + ar->i_ci;
  fp = getluaproto(ci);
  if (fp) {  /* is a Lua function? */
    name = luaF_getlocalname(fp, n, currentpc(L, ci));
    if (name)
      luaA_pushobject(L, ci->base+(n-1));  /* push value */
  }
  lua_unlock(L);
  return name;
}


LUA_API const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n) {
  const char *name;
  CallInfo *ci;
  Proto *fp;
  lua_lock(L);
  name = NULL;
  ci = L->base_ci + ar->i_ci;
  fp = getluaproto(ci);
  L->top--;  /* pop new value */
  if (fp) {  /* is a Lua function? */
    name = luaF_getlocalname(fp, n, currentpc(L, ci));
    if (!name || name[0] == '(')  /* `(' starts private locals */
      name = NULL;
    else
      setobj(ci->base+(n-1), L->top);
  }
  lua_unlock(L);
  return name;
}


static void infoLproto (lua_Debug *ar, Proto *f) {
  ar->source = getstr(f->source);
  ar->linedefined = f->lineDefined;
  ar->what = "Lua";
}


static void funcinfo (lua_State *L, lua_Debug *ar, StkId func) {
  Closure *cl;
  if (ttype(func) == LUA_TFUNCTION)
    cl = clvalue(func);
  else {
    luaD_runerror(L, "value for `lua_getinfo' is not a function");
    cl = NULL;  /* to avoid warnings */
  }
  if (cl->c.isC) {
    ar->source = "=C";
    ar->linedefined = -1;
    ar->what = "C";
  }
  else
    infoLproto(ar, cl->l.p);
  luaO_chunkid(ar->short_src, ar->source, LUA_IDSIZE);
  if (ar->linedefined == 0)
    ar->what = "main";
}


static const char *travglobals (lua_State *L, const TObject *o) {
  Table *g = hvalue(gt(L));
  int i = sizenode(g);
  while (i--) {
    Node *n = node(g, i);
    if (luaO_equalObj(o, val(n)) && ttype(key(n)) == LUA_TSTRING)
      return getstr(tsvalue(key(n)));
  }
  return NULL;
}


static void getname (lua_State *L, const TObject *f, lua_Debug *ar) {
  /* try to find a name for given function */
  if ((ar->name = travglobals(L, f)) != NULL)
    ar->namewhat = "global";
  else ar->namewhat = "";  /* not found */
}


LUA_API int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
  StkId f;
  CallInfo *ci;
  int status = 1;
  lua_lock(L);
  if (*what != '>') {  /* function is active? */
    ci = L->base_ci + ar->i_ci;
    f = ci->base - 1;
  }
  else {
    what++;  /* skip the `>' */
    ci = NULL;
    f = L->top - 1;
  }
  for (; *what; what++) {
    switch (*what) {
      case 'S': {
        funcinfo(L, ar, f);
        break;
      }
      case 'l': {
        ar->currentline = (ci) ? currentline(L, ci) : -1;
        break;
      }
      case 'u': {
        ar->nups = (ttype(f) == LUA_TFUNCTION) ? clvalue(f)->c.nupvalues : 0;
        break;
      }
      case 'n': {
        ar->namewhat = (ci) ? getfuncname(L, ci, &ar->name) : NULL;
        if (ar->namewhat == NULL)
          getname(L, f, ar);
        break;
      }
      case 'f': {
        setobj(L->top, f);
        status = 2;
        break;
      }
      default: status = 0;  /* invalid option */
    }
  }
  if (!ci) L->top--;  /* pop function */
  if (status == 2) incr_top(L);
  lua_unlock(L);
  return status;
}


/*
** {======================================================
** Symbolic Execution and code checker
** =======================================================
*/

#define check(x)		if (!(x)) return 0;

#define checkjump(pt,pc)	check(0 <= pc && pc < pt->sizecode)

#define checkreg(pt,reg)	check((reg) < (pt)->maxstacksize)



static int precheck (const Proto *pt) {
  check(pt->maxstacksize <= MAXSTACK);
  lua_assert(pt->numparams+pt->is_vararg <= pt->maxstacksize);
  check(GET_OPCODE(pt->code[pt->sizecode-1]) == OP_RETURN);
  return 1;
}


static int checkopenop (const Proto *pt, int pc) {
  Instruction i = pt->code[pc+1];
  switch (GET_OPCODE(i)) {
    case OP_CALL:
    case OP_TAILCALL:
    case OP_RETURN: {
      check(GETARG_B(i) == 0);
      return 1;
    }
    case OP_SETLISTO: return 1;
    default: return 0;  /* invalid instruction after an open call */
  }
}


static Instruction luaG_symbexec (const Proto *pt, int lastpc, int reg) {
  int pc;
  int last;  /* stores position of last instruction that changed `reg' */
  last = pt->sizecode-1;  /* points to final return (a `neutral' instruction) */
  if (reg == NO_REG)  /* full check? */
    check(precheck(pt));
  for (pc = 0; pc < lastpc; pc++) {
    const Instruction i = pt->code[pc];
    OpCode op = GET_OPCODE(i);
    int a = GETARG_A(i);
    int b = 0;
    int c = 0;
    checkreg(pt, a);
    switch (getOpMode(op)) {
      case iABC: {
        b = GETARG_B(i);
        c = GETARG_C(i);
        if (testOpMode(op, OpModeBreg))
          checkreg(pt, b);
        if (testOpMode(op, OpModeCreg))
          check(c < pt->maxstacksize ||
               (c >= MAXSTACK && c-MAXSTACK < pt->sizek));
        break;
      }
      case iABx: {
        b = GETARG_Bx(i);
        if (testOpMode(op, OpModeK)) check(b < pt->sizek);
        break;
      }
      case iAsBx: {
        b = GETARG_sBx(i);
        break;
      }
    }
    if (testOpMode(op, OpModesetA)) {
      if (a == reg) last = pc;  /* change register `a' */
    }
    if (testOpMode(op, OpModeT))
      check(pc+2 < pt->sizecode);  /* check skip */
    switch (op) {
      case OP_LOADBOOL: {
        check(c == 0 || pc+2 < pt->sizecode);  /* check its jump */
        break;
      }
      case OP_LOADNIL: {
        if (a <= reg && reg <= b)
          last = pc;  /* set registers from `a' to `b' */
        break;
      }
      case OP_GETUPVAL:
      case OP_SETUPVAL: {
        check(b < pt->nupvalues);
        break;
      }
      case OP_GETGLOBAL:
      case OP_SETGLOBAL: {
        check(ttype(&pt->k[b]) == LUA_TSTRING);
        break;
      }
      case OP_SELF: {
        checkreg(pt, a+1);
        if (reg == a+1) last = pc;
        break;
      }
      case OP_CONCAT: {
        /* `c' is a register, and at least two operands */
        check(c < MAXSTACK && b < c);
        break;
      }
      case OP_FORLOOP:
        checkreg(pt, a+2);
        /* go through */
      case OP_JMP: {
        int dest = pc+1+b;
	check(0 <= dest && dest < pt->sizecode);
        /* not full check and jump is forward and do not skip `lastpc'? */
        if (reg != NO_REG && pc < dest && dest <= lastpc)
          pc += b;  /* do the jump */
        break;
      }
      case OP_TFORLOOP: {
        checkreg(pt, a+2+c);
        check(pc+2 < pt->sizecode);  /* check skip */
        break;
      }
      case OP_CALL: {
        if (b != 0) {
          checkreg(pt, a+b-1);
        }
        c--;  /* c = num. returns */
        if (c == LUA_MULTRET) {
          check(checkopenop(pt, pc));
        }
        else if (c != 0)
          checkreg(pt, a+c-1);
        if (reg >= a) last = pc;  /* affect all registers above base */
        break;
      }
      case OP_TAILCALL:
      case OP_RETURN: {
        b--;  /* b = num. returns */
        if (b > 0) checkreg(pt, a+b-1);
        break;
      }
      case OP_SETLIST: {
        checkreg(pt, a + (b&(LFIELDS_PER_FLUSH-1)) + 1);
        break;
      }
      case OP_CLOSURE: {
        int nup;
        check(b < pt->sizep);
        nup = pt->p[b]->nupvalues;
        check(pc + nup < pt->sizecode);
        for (; nup>0; nup--) {
          OpCode op1 = GET_OPCODE(pt->code[pc+nup]);
          check(op1 == OP_GETUPVAL || op1 == OP_MOVE);
        }
        break;
      }
      default: break;
    }
  }
  return pt->code[last];
}

/* }====================================================== */


int luaG_checkcode (const Proto *pt) {
  return luaG_symbexec(pt, pt->sizecode, NO_REG);
}


static const char *kname (Proto *p, int c) {
  c = c - MAXSTACK;
  if (c >= 0 && ttype(&p->k[c]) == LUA_TSTRING)
    return svalue(&p->k[c]);
  else
    return "?";
}


static const char *getobjname (lua_State *L, CallInfo *ci, int stackpos,
                               const char **name) {
  if (isLmark(ci)) {  /* an active Lua function? */
    Proto *p = ci_func(ci)->l.p;
    int pc = currentpc(L, ci);
    Instruction i;
    *name = luaF_getlocalname(p, stackpos+1, pc);
    if (*name)  /* is a local? */
      return "local";
    i = luaG_symbexec(p, pc, stackpos);  /* try symbolic execution */
    lua_assert(pc != -1);
    switch (GET_OPCODE(i)) {
      case OP_GETGLOBAL: {
        lua_assert(ttype(&p->k[GETARG_Bx(i)]) == LUA_TSTRING);
        *name = svalue(&p->k[GETARG_Bx(i)]);
        return "global";
      }
      case OP_MOVE: {
        int a = GETARG_A(i);
        int b = GETARG_B(i);  /* move from `b' to `a' */
        if (b < a)
          return getobjname(L, ci, b, name);  /* get name for `b' */
        break;
      }
      case OP_GETTABLE: {
        *name = luaF_getlocalname(p, GETARG_B(i)+1, pc);
        if (*name && *name[0] == '*') {
          *name = kname(p, GETARG_C(i));
          return "global";
        }
        *name = kname(p, GETARG_C(i));
        return "field";
        break;
      }
      case OP_SELF: {
        *name = kname(p, GETARG_C(i));
        return "method";
        break;
      }
      default: break;
    }
  }
  return NULL;  /* no useful name found */
}


static Instruction getcurrentinstr (lua_State *L, CallInfo *ci) {
  if (ci == L->base_ci || !isLmark(ci))
    return (Instruction)(-1);  /* not an active Lua function */
  else
    return ci_func(ci)->l.p->code[currentpc(L, ci)];
}


static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
  Instruction i;
  ci--;  /* calling function */
  i = getcurrentinstr(L, ci);
  return (GET_OPCODE(i) == OP_CALL ? getobjname(L, ci, GETARG_A(i), name)
                                   : NULL);  /* no useful name found */
}


/* only ANSI way to check whether a pointer points to an array */
static int isinstack (CallInfo *ci, const TObject *o) {
  StkId p;
  for (p = ci->base; p < ci->top; p++)
    if (o == p) return 1;
  return 0;
}


void luaG_typeerror (lua_State *L, const TObject *o, const char *op) {
  const char *name;
  const char *t = luaT_typenames[ttype(o)];
  const char *kind = NULL;
  if (isinstack(L->ci, o))
    kind = getobjname(L, L->ci, o - L->ci->base, &name);
  if (kind)
    luaO_verror(L, "attempt to %.30s %.20s `%.40s' (a %.10s value)",
                op, kind, name, t);
  else
    luaO_verror(L, "attempt to %.30s a %.10s value", op, t);
}


void luaG_concaterror (lua_State *L, StkId p1, StkId p2) {
  if (ttype(p1) == LUA_TSTRING) p1 = p2;
  lua_assert(ttype(p1) != LUA_TSTRING);
  luaG_typeerror(L, p1, "concat");
}


void luaG_aritherror (lua_State *L, StkId p1, const TObject *p2) {
  TObject temp;
  if (luaV_tonumber(p1, &temp) == NULL)
    p2 = p1;  /* first operand is wrong */
  luaG_typeerror(L, p2, "perform arithmetic on");
}


void luaG_ordererror (lua_State *L, const TObject *p1, const TObject *p2) {
  const char *t1 = luaT_typenames[ttype(p1)];
  const char *t2 = luaT_typenames[ttype(p2)];
  if (t1[2] == t2[2])
    luaO_verror(L, "attempt to compare two %.10s values", t1);
  else
    luaO_verror(L, "attempt to compare %.10s with %.10s", t1, t2);
}