/*

** $Id: ldo.c,v 2.38.1.3 2008/01/18 22:31:22 roberto Exp $

** Stack and Call structure of Lua

** See Copyright Notice in lua.h

*/

#include <setjmp.h>

#include <stdlib.h>

#include <string.h>

#define ldo_c

#define LUA_CORE

#include "lua.h"

#include "ldebug.h"

#include "ldo.h"

#include "lfunc.h"

#include "lgc.h"

#include "lmem.h"

#include "lobject.h"

#include "lopcodes.h"

#include "lparser.h"

#include "lstate.h"

#include "lstring.h"

#include "ltable.h"

#include "ltm.h"

#include "lundump.h"

#include "lvm.h"

#include "lzio.h"

/*

** {======================================================

** Error-recovery functions

** =======================================================

*/

/* chain list of long jump buffers */

struct lua_longjmp {

  struct lua_longjmp *previous;

  luai_jmpbuf b;

  volatile int status;  /* error code */

};

void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) {

  switch (errcode) {

    case LUA_ERRMEM: {

      setsvalue2s(L, oldtop, luaS_newliteral(L, MEMERRMSG));

      break;

    }

    case LUA_ERRERR: {

      setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));

      break;

    }

    case LUA_ERRSYNTAX:

    case LUA_ERRRUN: {

      setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */

      break;

    }

  }

  L->top = oldtop + 1;

}

static void restore_stack_limit (lua_State *L) {

  lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);

  if (L->size_ci > LUAI_MAXCALLS) {  /* there was an overflow? */

    int inuse = cast_int(L->ci - L->base_ci);

    if (inuse + 1 < LUAI_MAXCALLS)  /* can `undo' overflow? */

      luaD_reallocCI(L, LUAI_MAXCALLS);

  }

}

static void resetstack (lua_State *L, int status) {

  L->ci = L->base_ci;

  L->base = L->ci->base;

  luaF_close(L, L->base);  /* close eventual pending closures */

  luaD_seterrorobj(L, status, L->base);

  L->nCcalls = L->baseCcalls;

  L->allowhook = 1;

  restore_stack_limit(L);

  L->errfunc = 0;

  L->errorJmp = NULL;

}

void luaD_throw (lua_State *L, int errcode) {

  if (L->errorJmp) {

    L->errorJmp->status = errcode;

    LUAI_THROW(L, L->errorJmp);

  }

  else {

    L->status = cast_byte(errcode);

    if (G(L)->panic) {

      resetstack(L, errcode);

      lua_unlock(L);

      G(L)->panic(L);

    }

    exit(EXIT_FAILURE);

  }

}

int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {

  struct lua_longjmp lj;

  lj.status = 0;

  lj.previous = L->errorJmp;  /* chain new error handler */

  L->errorJmp = &lj;

  LUAI_TRY(L, &lj,

    (*f)(L, ud);

  );

  L->errorJmp = lj.previous;  /* restore old error handler */

  return lj.status;

}

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

static void correctstack (lua_State *L, TValue *oldstack) {

  CallInfo *ci;

  GCObject *up;

  L->top = (L->top - oldstack) + L->stack;

  for (up = L->openupval; up != NULL; up = up->gch.next)

    gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;

  for (ci = L->base_ci; ci <= L->ci; ci++) {

    ci->top = (ci->top - oldstack) + L->stack;

    ci->base = (ci->base - oldstack) + L->stack;

    ci->func = (ci->func - oldstack) + L->stack;

  }

  L->base = (L->base - oldstack) + L->stack;

}

void luaD_reallocstack (lua_State *L, int newsize) {

  TValue *oldstack = L->stack;

  int realsize = newsize + 1 + EXTRA_STACK;

  lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);

  luaM_reallocvector(L, L->stack, L->stacksize, realsize, TValue);

  L->stacksize = realsize;

  L->stack_last = L->stack+newsize;

  correctstack(L, oldstack);

}

void luaD_reallocCI (lua_State *L, int newsize) {

  CallInfo *oldci = L->base_ci;

  luaM_reallocvector(L, L->base_ci, L->size_ci, newsize, CallInfo);

  L->size_ci = newsize;

  L->ci = (L->ci - oldci) + L->base_ci;

  L->end_ci = L->base_ci + L->size_ci - 1;

}

void luaD_growstack (lua_State *L, int n) {

  if (n <= L->stacksize)  /* double size is enough? */

    luaD_reallocstack(L, 2*L->stacksize);

  else

    luaD_reallocstack(L, L->stacksize + n);

}

static CallInfo *growCI (lua_State *L) {

  if (L->size_ci > LUAI_MAXCALLS)  /* overflow while handling overflow? */

    luaD_throw(L, LUA_ERRERR);

  else {

    luaD_reallocCI(L, 2*L->size_ci);

    if (L->size_ci > LUAI_MAXCALLS)

      luaG_runerror(L, "stack overflow");

  }

  return ++L->ci;

}

void luaD_callhook (lua_State *L, int event, int line) {

  lua_Hook hook = L->hook;

  if (hook && L->allowhook) {

    ptrdiff_t top = savestack(L, L->top);

    ptrdiff_t ci_top = savestack(L, L->ci->top);

    lua_Debug ar;

    ar.event = event;

    ar.currentline = line;

    if (event == LUA_HOOKTAILRET)

      ar.i_ci = 0;  /* tail call; no debug information about it */

    else

      ar.i_ci = cast_int(L->ci - L->base_ci);

    luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */

    L->ci->top = L->top + LUA_MINSTACK;

    lua_assert(L->ci->top <= L->stack_last);

    L->allowhook = 0;  /* cannot call hooks inside a hook */

    lua_unlock(L);

    (*hook)(L, &ar);

    lua_lock(L);

    lua_assert(!L->allowhook);

    L->allowhook = 1;

    L->ci->top = restorestack(L, ci_top);

    L->top = restorestack(L, top);

  }

}

static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {

  int i;

  int nfixargs = p->numparams;

  Table *htab = NULL;

  StkId base, fixed;

  for (; actual < nfixargs; ++actual)

    setnilvalue(L->top++);

#if defined(LUA_COMPAT_VARARG)

  if (p->is_vararg & VARARG_NEEDSARG) { /* compat. with old-style vararg? */

    int nvar = actual - nfixargs;  /* number of extra arguments */

    lua_assert(p->is_vararg & VARARG_HASARG);

    luaC_checkGC(L);

    htab = luaH_new(L, nvar, 1);  /* create `arg' table */

    for (i=0; i<nvar; i++)  /* put extra arguments into `arg' table */

      setobj2n(L, luaH_setnum(L, htab, i+1), L->top - nvar + i);

    /* store counter in field `n' */

    setnvalue(luaH_setstr(L, htab, luaS_newliteral(L, "n")), cast_num(nvar));

  }

#endif

  /* move fixed parameters to final position */

  fixed = L->top - actual;  /* first fixed argument */

  base = L->top;  /* final position of first argument */

  for (i=0; i<nfixargs; i++) {

    setobjs2s(L, L->top++, fixed+i);

    setnilvalue(fixed+i);

  }

  /* add `arg' parameter */

  if (htab) {

    sethvalue(L, L->top++, htab);

    lua_assert(iswhite(obj2gco(htab)));

  }

  return base;

}

static StkId tryfuncTM (lua_State *L, StkId func) {

  const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);

  StkId p;

  ptrdiff_t funcr = savestack(L, func);

  if (!ttisfunction(tm))

    luaG_typeerror(L, func, "call");

  /* Open a hole inside the stack at `func' */

  for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);

  incr_top(L);

  func = restorestack(L, funcr);  /* previous call may change stack */

  setobj2s(L, func, tm);  /* tag method is the new function to be called */

  return func;

}

#define inc_ci(L) \

  ((L->ci == L->end_ci) ? growCI(L) : \

   (condhardstacktests(luaD_reallocCI(L, L->size_ci)), ++L->ci))

int luaD_precall (lua_State *L, StkId func, int nresults) {

  LClosure *cl;

  ptrdiff_t funcr;

  if (!ttisfunction(func)) /* `func' is not a function? */

    func = tryfuncTM(L, func);  /* check the `function' tag method */

  funcr = savestack(L, func);

  cl = &clvalue(func)->l;

  L->ci->savedpc = L->savedpc;

  if (!cl->isC) {  /* Lua function? prepare its call */

    CallInfo *ci;

    StkId st, base;

    Proto *p = cl->p;

    luaD_checkstack(L, p->maxstacksize);

    func = restorestack(L, funcr);

    if (!p->is_vararg) {  /* no varargs? */

      base = func + 1;

      if (L->top > base + p->numparams)

        L->top = base + p->numparams;

    }

    else {  /* vararg function */

      int nargs = cast_int(L->top - func) - 1;

      base = adjust_varargs(L, p, nargs);

      func = restorestack(L, funcr);  /* previous call may change the stack */

    }

    ci = inc_ci(L);  /* now `enter' new function */

    ci->func = func;

    L->base = ci->base = base;

    ci->top = L->base + p->maxstacksize;

    lua_assert(ci->top <= L->stack_last);

    L->savedpc = p->code;  /* starting point */

    ci->tailcalls = 0;

    ci->nresults = nresults;

    for (st = L->top; st < ci->top; st++)

      setnilvalue(st);

    L->top = ci->top;

    if (L->hookmask & LUA_MASKCALL) {

      L->savedpc++;  /* hooks assume 'pc' is already incremented */

      luaD_callhook(L, LUA_HOOKCALL, -1);

      L->savedpc--;  /* correct 'pc' */

    }

    return PCRLUA;

  }

  else {  /* if is a C function, call it */

    CallInfo *ci;

    int n;

    luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */

    ci = inc_ci(L);  /* now `enter' new function */

    ci->func = restorestack(L, funcr);

    L->base = ci->base = ci->func + 1;

    ci->top = L->top + LUA_MINSTACK;

    lua_assert(ci->top <= L->stack_last);

    ci->nresults = nresults;

    if (L->hookmask & LUA_MASKCALL)

      luaD_callhook(L, LUA_HOOKCALL, -1);

    lua_unlock(L);

    n = (*curr_func(L)->c.f)(L);  /* do the actual call */

    lua_lock(L);

    if (n < 0)  /* yielding? */

      return PCRYIELD;

    else {

      luaD_poscall(L, L->top - n);

      return PCRC;

    }

  }

}

static StkId callrethooks (lua_State *L, StkId firstResult) {

  ptrdiff_t fr = savestack(L, firstResult);  /* next call may change stack */

  luaD_callhook(L, LUA_HOOKRET, -1);

  if (f_isLua(L->ci)) {  /* Lua function? */

    while ((L->hookmask & LUA_MASKRET) && L->ci->tailcalls--) /* tail calls */

      luaD_callhook(L, LUA_HOOKTAILRET, -1);

  }

  return restorestack(L, fr);

}

int luaD_poscall (lua_State *L, StkId firstResult) {

  StkId res;

  int wanted, i;

  CallInfo *ci;

  if (L->hookmask & LUA_MASKRET)

    firstResult = callrethooks(L, firstResult);

  ci = L->ci--;

  res = ci->func;  /* res == final position of 1st result */

  wanted = ci->nresults;

  L->base = (ci - 1)->base;  /* restore base */

  L->savedpc = (ci - 1)->savedpc;  /* restore savedpc */

  /* move results to correct place */

  for (i = wanted; i != 0 && firstResult < L->top; i--)

    setobjs2s(L, res++, firstResult++);

  while (i-- > 0)

    setnilvalue(res++);

  L->top = res;

  return (wanted - LUA_MULTRET);  /* 0 iff wanted == LUA_MULTRET */

}

/*

** Call a function (C or Lua). The function to be called is at *func.

** The arguments are on the stack, right after the function.

** When returns, all the results are on the stack, starting at the original

** function position.

*/ 

void luaD_call (lua_State *L, StkId func, int nResults) {

  if (++L->nCcalls >= LUAI_MAXCCALLS) {

    if (L->nCcalls == LUAI_MAXCCALLS)

      luaG_runerror(L, "C stack overflow");

    else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))

      luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */

  }

  if (luaD_precall(L, func, nResults) == PCRLUA)  /* is a Lua function? */

    luaV_execute(L, 1);  /* call it */

  L->nCcalls--;

  luaC_checkGC(L);

}

static void resume (lua_State *L, void *ud) {

  StkId firstArg = cast(StkId, ud);

  CallInfo *ci = L->ci;

  if (L->status == 0) {  /* start coroutine? */

    lua_assert(ci == L->base_ci && firstArg > L->base);

    if (luaD_precall(L, firstArg - 1, LUA_MULTRET) != PCRLUA)

      return;

  }

  else {  /* resuming from previous yield */

    lua_assert(L->status == LUA_YIELD);

    L->status = 0;

    if (!f_isLua(ci)) {  /* `common' yield? */

      /* finish interrupted execution of `OP_CALL' */

      lua_assert(GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_CALL ||

                 GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_TAILCALL);

      if (luaD_poscall(L, firstArg))  /* complete it... */

        L->top = L->ci->top;  /* and correct top if not multiple results */

    }

    else  /* yielded inside a hook: just continue its execution */

      L->base = L->ci->base;

  }

  luaV_execute(L, cast_int(L->ci - L->base_ci));

}

static int resume_error (lua_State *L, const char *msg) {

  L->top = L->ci->base;

  setsvalue2s(L, L->top, luaS_new(L, msg));

  incr_top(L);

  lua_unlock(L);

  return LUA_ERRRUN;

}

LUA_API int lua_resume (lua_State *L, int nargs) {

  int status;

  lua_lock(L);

  if (L->status != LUA_YIELD && (L->status != 0 || L->ci != L->base_ci))

      return resume_error(L, "cannot resume non-suspended coroutine");

  if (L->nCcalls >= LUAI_MAXCCALLS)

    return resume_error(L, "C stack overflow");

  luai_userstateresume(L, nargs);

  lua_assert(L->errfunc == 0);

  L->baseCcalls = ++L->nCcalls;

  status = luaD_rawrunprotected(L, resume, L->top - nargs);

  if (status != 0) {  /* error? */

    L->status = cast_byte(status);  /* mark thread as `dead' */

    luaD_seterrorobj(L, status, L->top);

    L->ci->top = L->top;

  }

  else {

    lua_assert(L->nCcalls == L->baseCcalls);

    status = L->status;

  }

  --L->nCcalls;

  lua_unlock(L);

  return status;

}

LUA_API int lua_yield (lua_State *L, int nresults) {

  luai_userstateyield(L, nresults);

  lua_lock(L);

  if (L->nCcalls > L->baseCcalls)

    luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");

  L->base = L->top - nresults;  /* protect stack slots below */

  L->status = LUA_YIELD;

  lua_unlock(L);

  return -1;

}

int luaD_pcall (lua_State *L, Pfunc func, void *u,

                ptrdiff_t old_top, ptrdiff_t ef) {

  int status;

  unsigned short oldnCcalls = L->nCcalls;

  ptrdiff_t old_ci = saveci(L, L->ci);

  lu_byte old_allowhooks = L->allowhook;

  ptrdiff_t old_errfunc = L->errfunc;

  L->errfunc = ef;

  status = luaD_rawrunprotected(L, func, u);

  if (status != 0) {  /* an error occurred? */

    StkId oldtop = restorestack(L, old_top);

    luaF_close(L, oldtop);  /* close eventual pending closures */

    luaD_seterrorobj(L, status, oldtop);

    L->nCcalls = oldnCcalls;

    L->ci = restoreci(L, old_ci);

    L->base = L->ci->base;

    L->savedpc = L->ci->savedpc;

    L->allowhook = old_allowhooks;

    restore_stack_limit(L);

  }

  L->errfunc = old_errfunc;

  return status;

}

/*

** Execute a protected parser.

*/

struct SParser {  /* data to `f_parser' */

  ZIO *z;

  Mbuffer buff;  /* buffer to be used by the scanner */

  const char *name;

};

static void f_parser (lua_State *L, void *ud) {

  int i;

  Proto *tf;

  Closure *cl;

  struct SParser *p = cast(struct SParser *, ud);

  int c = luaZ_lookahead(p->z);

  luaC_checkGC(L);

  tf = ((c == LUA_SIGNATURE[0]) ? luaU_undump : luaY_parser)(L, p->z,

                                                             &p->buff, p->name);

  cl = luaF_newLclosure(L, tf->nups, hvalue(gt(L)));

  cl->l.p = tf;

  for (i = 0; i < tf->nups; i++)  /* initialize eventual upvalues */

    cl->l.upvals[i] = luaF_newupval(L);

  setclvalue(L, L->top, cl);

  incr_top(L);

}

int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) {

  struct SParser p;

  int status;

  p.z = z; p.name = name;

  luaZ_initbuffer(L, &p.buff);

  status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);

  luaZ_freebuffer(L, &p.buff);

  return status;

}