/*
** $Id: ldo.c,v 2.38.1.4 2012/01/18 02:27:10 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);
        luaD_checkstack(L, p->maxstacksize);
        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;
}
