/*
** State and stack handling.
** Copyright (C) 2005-2014 Mike Pall. See Copyright Notice in luajit.h
**
** Portions taken verbatim or adapted from the Lua interpreter.
** Copyright (C) 1994-2008 Lua.org, PUC-Rio. See Copyright Notice in lua.h
*/

#define lj_state_c
#define LUA_CORE

#include "lj_obj.h"
#include "lj_gc.h"
#include "lj_err.h"
#include "lj_str.h"
#include "lj_tab.h"
#include "lj_func.h"
#include "lj_meta.h"
#include "lj_state.h"
#include "lj_frame.h"
#if LJ_HASFFI
    #include "lj_ctype.h"
#endif
#include "lj_trace.h"
#include "lj_dispatch.h"
#include "lj_vm.h"
#include "lj_lex.h"
#include "lj_alloc.h"

/* -- Stack handling ------------------------------------------------------ */

/* Stack sizes. */
#define LJ_STACK_MIN LUA_MINSTACK         /* Min. stack size. */
#define LJ_STACK_MAX LUAI_MAXSTACK        /* Max. stack size. */
#define LJ_STACK_START (2 * LJ_STACK_MIN) /* Starting stack size. */
#define LJ_STACK_MAXEX (LJ_STACK_MAX + 1 + LJ_STACK_EXTRA)

/* Explanation of LJ_STACK_EXTRA:
**
** Calls to metamethods store their arguments beyond the current top
** without checking for the stack limit. This avoids stack resizes which
** would invalidate passed TValue pointers. The stack check is performed
** later by the function header. This can safely resize the stack or raise
** an error. Thus we need some extra slots beyond the current stack limit.
**
** Most metamethods need 4 slots above top (cont, mobj, arg1, arg2) plus
** one extra slot if mobj is not a function. Only lj_meta_tset needs 5
** slots above top, but then mobj is always a function. So we can get by
** with 5 extra slots.
*/

/* Resize stack slots and adjust pointers in state. */
static void resizestack(lua_State *L, MSize n)
{
    TValue *st, *oldst = tvref(L->stack);
    ptrdiff_t delta;
    MSize oldsize = L->stacksize;
    MSize realsize = n + 1 + LJ_STACK_EXTRA;
    GCobj *up;
    lua_assert((MSize)(tvref(L->maxstack) - oldst) ==
               L->stacksize - LJ_STACK_EXTRA - 1);
    st = (TValue *)lj_mem_realloc(L, tvref(L->stack),
                                  (MSize)(L->stacksize * sizeof(TValue)),
                                  (MSize)(realsize * sizeof(TValue)));
    setmref(L->stack, st);
    delta = (char *)st - (char *)oldst;
    setmref(L->maxstack, st + n);
    while (oldsize < realsize) /* Clear new slots. */
        setnilV(st + oldsize++);
    L->stacksize = realsize;
    L->base = (TValue *)((char *)L->base + delta);
    L->top = (TValue *)((char *)L->top + delta);
    for (up = gcref(L->openupval); up != NULL; up = gcnext(up))
        setmref(gco2uv(up)->v, (TValue *)((char *)uvval(gco2uv(up)) + delta));
    if (obj2gco(L) == gcref(G(L)->jit_L))
        setmref(G(L)->jit_base, mref(G(L)->jit_base, char) + delta);
}

/* Relimit stack after error, in case the limit was overdrawn. */
void lj_state_relimitstack(lua_State *L)
{
    if (L->stacksize > LJ_STACK_MAXEX &&
        L->top - tvref(L->stack) < LJ_STACK_MAX - 1)
        resizestack(L, LJ_STACK_MAX);
}

/* Try to shrink the stack (called from GC). */
void lj_state_shrinkstack(lua_State *L, MSize used)
{
    if (L->stacksize > LJ_STACK_MAXEX)
        return; /* Avoid stack shrinking while handling stack overflow. */
    if (4 * used < L->stacksize &&
        2 * (LJ_STACK_START + LJ_STACK_EXTRA) < L->stacksize &&
        obj2gco(L) !=
            gcref(G(L)->jit_L)) /* Don't shrink stack of live trace. */
        resizestack(L, L->stacksize >> 1);
}

/* Try to grow stack. */
void LJ_FASTCALL lj_state_growstack(lua_State *L, MSize need)
{
    MSize n;
    if (L->stacksize > LJ_STACK_MAXEX) /* Overflow while handling overflow? */
        lj_err_throw(L, LUA_ERRERR);
    n = L->stacksize + need;
    if (n > LJ_STACK_MAX) {
        n += 2 * LUA_MINSTACK;
    }
    else if (n < 2 * L->stacksize) {
        n = 2 * L->stacksize;
        if (n >= LJ_STACK_MAX)
            n = LJ_STACK_MAX;
    }
    resizestack(L, n);
    if (L->stacksize > LJ_STACK_MAXEX)
        lj_err_msg(L, LJ_ERR_STKOV);
}

void LJ_FASTCALL lj_state_growstack1(lua_State *L) { lj_state_growstack(L, 1); }

/* Allocate basic stack for new state. */
static void stack_init(lua_State *L1, lua_State *L)
{
    TValue *stend,
        *st = lj_mem_newvec(L, LJ_STACK_START + LJ_STACK_EXTRA, TValue);
    setmref(L1->stack, st);
    L1->stacksize = LJ_STACK_START + LJ_STACK_EXTRA;
    stend = st + L1->stacksize;
    setmref(L1->maxstack, stend - LJ_STACK_EXTRA - 1);
    L1->base = L1->top = st + 1;
    setthreadV(L1, st, L1); /* Needed for curr_funcisL() on empty stack. */
    while (st < stend)      /* Clear new slots. */
        setnilV(st++);
}

/* -- State handling ------------------------------------------------------ */

/* Open parts that may cause memory-allocation errors. */
static TValue *cpluaopen(lua_State *L, lua_CFunction dummy, void *ud)
{
    global_State *g = G(L);
    UNUSED(dummy);
    UNUSED(ud);
    stack_init(L, L);
    /* NOBARRIER: State initialization, all objects are white. */
    setgcref(L->env, obj2gco(lj_tab_new(L, 0, LJ_MIN_GLOBAL)));
    settabV(L, registry(L), lj_tab_new(L, 0, LJ_MIN_REGISTRY));
    lj_str_resize(L, LJ_MIN_STRTAB - 1);
    lj_meta_init(L);
    lj_lex_init(L);
    fixstring(lj_err_str(L, LJ_ERR_ERRMEM)); /* Preallocate memory error msg. */
    g->gc.threshold = 4 * g->gc.total;
    lj_trace_initstate(g);
    return NULL;
}

static void close_state(lua_State *L)
{
    global_State *g = G(L);
    lj_func_closeuv(L, tvref(L->stack));
    lj_gc_freeall(g);
    lua_assert(gcref(g->gc.root) == obj2gco(L));
    lua_assert(g->strnum == 0);
    lj_trace_freestate(g);
#if LJ_HASFFI
    lj_ctype_freestate(g);
#endif
    lj_mem_freevec(g, g->strhash, g->strmask + 1, GCRef);
    lj_str_freebuf(g, &g->tmpbuf);
    lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
    lua_assert(g->gc.total == sizeof(GG_State));
#ifndef LUAJIT_USE_SYSMALLOC
    if (g->allocf == lj_alloc_f)
        lj_alloc_destroy(g->allocd);
    else
#endif
        g->allocf(g->allocd, G2GG(g), sizeof(GG_State), 0);
}

#if LJ_64
lua_State *lj_state_newstate(lua_Alloc f, void *ud)
#else
LUA_API lua_State *lua_newstate(lua_Alloc f, void *ud)
#endif
{
    GG_State *GG = (GG_State *)f(ud, NULL, 0, sizeof(GG_State));
    lua_State *L = &GG->L;
    global_State *g = &GG->g;
    if (GG == NULL || !checkptr32(GG))
        return NULL;
    memset(GG, 0, sizeof(GG_State));
    L->gct = ~LJ_TTHREAD;
    L->marked = LJ_GC_WHITE0 | LJ_GC_FIXED | LJ_GC_SFIXED; /* Prevent free. */
    L->dummy_ffid = FF_C;
    setmref(L->glref, g);
    g->gc.currentwhite = LJ_GC_WHITE0 | LJ_GC_FIXED;
    g->strempty.marked = LJ_GC_WHITE0;
    g->strempty.gct = ~LJ_TSTR;
    g->allocf = f;
    g->allocd = ud;
    setgcref(g->mainthref, obj2gco(L));
    setgcref(g->uvhead.prev, obj2gco(&g->uvhead));
    setgcref(g->uvhead.next, obj2gco(&g->uvhead));
    g->strmask = ~(MSize)0;
    setnilV(registry(L));
    setnilV(&g->nilnode.val);
    setnilV(&g->nilnode.key);
    setmref(g->nilnode.freetop, &g->nilnode);
    lj_str_initbuf(&g->tmpbuf);
    g->gc.state = GCSpause;
    setgcref(g->gc.root, obj2gco(L));
    setmref(g->gc.sweep, &g->gc.root);
    g->gc.total = sizeof(GG_State);
    g->gc.pause = LUAI_GCPAUSE;
    g->gc.stepmul = LUAI_GCMUL;
    lj_dispatch_init((GG_State *)L);
    L->status =
        LUA_ERRERR + 1; /* Avoid touching the stack upon memory error. */
    if (lj_vm_cpcall(L, NULL, NULL, cpluaopen) != 0) {
        /* Memory allocation error: free partial state. */
        close_state(L);
        return NULL;
    }
    L->status = 0;
    return L;
}

static TValue *cpfinalize(lua_State *L, lua_CFunction dummy, void *ud)
{
    UNUSED(dummy);
    UNUSED(ud);
    lj_gc_finalize_cdata(L);
    lj_gc_finalize_udata(L);
    /* Frame pop omitted. */
    return NULL;
}

LUA_API void lua_close(lua_State *L)
{
    global_State *g = G(L);
    int i;
    L = mainthread(g); /* Only the main thread can be closed. */
    lj_func_closeuv(L, tvref(L->stack));
    lj_gc_separateudata(g, 1); /* Separate udata which have GC metamethods. */
#if LJ_HASJIT
    G2J(g)->flags &= ~JIT_F_ON;
    G2J(g)->state = LJ_TRACE_IDLE;
    lj_dispatch_update(g);
#endif
    for (i = 0;;) {
        hook_enter(g);
        L->status = 0;
        L->cframe = NULL;
        L->base = L->top = tvref(L->stack) + 1;
        if (lj_vm_cpcall(L, NULL, NULL, cpfinalize) == 0) {
            if (++i >= 10)
                break;
            lj_gc_separateudata(g, 1);        /* Separate udata again. */
            if (gcref(g->gc.mmudata) == NULL) /* Until nothing is left to do. */
                break;
        }
    }
    close_state(L);
}

lua_State *lj_state_new(lua_State *L)
{
    lua_State *L1 = lj_mem_newobj(L, lua_State);
    L1->gct = ~LJ_TTHREAD;
    L1->dummy_ffid = FF_C;
    L1->status = 0;
    L1->stacksize = 0;
    setmref(L1->stack, NULL);
    L1->cframe = NULL;
    /* NOBARRIER: The lua_State is new (marked white). */
    setgcrefnull(L1->openupval);
    setmrefr(L1->glref, L->glref);
    setgcrefr(L1->env, L->env);
    stack_init(L1, L); /* init stack */
    lua_assert(iswhite(obj2gco(L1)));
    return L1;
}

void LJ_FASTCALL lj_state_free(global_State *g, lua_State *L)
{
    lua_assert(L != mainthread(g));
    lj_func_closeuv(L, tvref(L->stack));
    lua_assert(gcref(L->openupval) == NULL);
    lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
    lj_mem_freet(g, L);
}
