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lua/ldo.c

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/*
** $Id: ldo.c,v 2.115 2014/03/21 13:52:33 roberto Exp roberto $
** 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 "lapi.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
** =======================================================
*/
/*
** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
** default, Lua handles errors with exceptions when compiling as
** C++ code, with _longjmp/_setjmp when asked to use them, and with
** longjmp/setjmp otherwise.
*/
#if !defined(LUAI_THROW) /* { */
#if defined(__cplusplus) && !defined(LUA_USE_LONGJMP) /* { */
/* C++ exceptions */
#define LUAI_THROW(L,c) throw(c)
#define LUAI_TRY(L,c,a) \
try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
#define luai_jmpbuf int /* dummy variable */
#elif defined(LUA_USE_POSIX) /* }{ */
/* in POSIX, try _longjmp/_setjmp (more efficient) */
#define LUAI_THROW(L,c) _longjmp((c)->b, 1)
#define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a }
#define luai_jmpbuf jmp_buf
#else /* }{ */
/* ANSI handling with long jumps */
#define LUAI_THROW(L,c) longjmp((c)->b, 1)
#define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
#define luai_jmpbuf jmp_buf
#endif /* } */
#endif /* } */
/* chain list of long jump buffers */
struct lua_longjmp {
struct lua_longjmp *previous;
luai_jmpbuf b;
volatile int status; /* error code */
};
static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
switch (errcode) {
case LUA_ERRMEM: { /* memory error? */
setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
break;
}
case LUA_ERRERR: {
setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
break;
}
default: {
setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
break;
}
}
L->top = oldtop + 1;
}
l_noret luaD_throw (lua_State *L, int errcode) {
if (L->errorJmp) { /* thread has an error handler? */
L->errorJmp->status = errcode; /* set status */
LUAI_THROW(L, L->errorJmp); /* jump to it */
}
else { /* thread has no error handler */
L->status = cast_byte(errcode); /* mark it as dead */
if (G(L)->mainthread->errorJmp) { /* main thread has a handler? */
setobjs2s(L, G(L)->mainthread->top++, L->top - 1); /* copy error obj. */
luaD_throw(G(L)->mainthread, errcode); /* re-throw in main thread */
}
else { /* no handler at all; abort */
if (G(L)->panic) { /* panic function? */
lua_unlock(L);
G(L)->panic(L); /* call it (last chance to jump out) */
}
abort();
}
}
}
int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
unsigned short oldnCcalls = L->nCcalls;
struct lua_longjmp lj;
lj.status = LUA_OK;
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 */
L->nCcalls = oldnCcalls;
return lj.status;
}
/* }====================================================== */
static void correctstack (lua_State *L, TValue *oldstack) {
CallInfo *ci;
UpVal *up;
L->top = (L->top - oldstack) + L->stack;
for (up = L->openupval; up != NULL; up = up->u.open.next)
up->v = (up->v - oldstack) + L->stack;
for (ci = L->ci; ci != NULL; ci = ci->previous) {
ci->top = (ci->top - oldstack) + L->stack;
ci->func = (ci->func - oldstack) + L->stack;
if (isLua(ci))
ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
}
}
/* some space for error handling */
#define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
void luaD_reallocstack (lua_State *L, int newsize) {
TValue *oldstack = L->stack;
int lim = L->stacksize;
lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
for (; lim < newsize; lim++)
setnilvalue(L->stack + lim); /* erase new segment */
L->stacksize = newsize;
L->stack_last = L->stack + newsize - EXTRA_STACK;
correctstack(L, oldstack);
}
void luaD_growstack (lua_State *L, int n) {
int size = L->stacksize;
if (size > LUAI_MAXSTACK) /* error after extra size? */
luaD_throw(L, LUA_ERRERR);
else {
int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
int newsize = 2 * size;
if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
if (newsize < needed) newsize = needed;
if (newsize > LUAI_MAXSTACK) { /* stack overflow? */
luaD_reallocstack(L, ERRORSTACKSIZE);
luaG_runerror(L, "stack overflow");
}
else
luaD_reallocstack(L, newsize);
}
}
static int stackinuse (lua_State *L) {
CallInfo *ci;
StkId lim = L->top;
for (ci = L->ci; ci != NULL; ci = ci->previous) {
lua_assert(ci->top <= L->stack_last);
if (lim < ci->top) lim = ci->top;
}
return cast_int(lim - L->stack) + 1; /* part of stack in use */
}
void luaD_shrinkstack (lua_State *L) {
int inuse = stackinuse(L);
int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
if (L->stacksize > LUAI_MAXSTACK) /* was handling stack overflow? */
luaE_freeCI(L); /* free all CIs (list grew because of an error) */
else
luaE_shrinkCI(L); /* shrink list */
if (inuse > LUAI_MAXSTACK || /* still handling stack overflow? */
goodsize >= L->stacksize) /* would grow instead of shrink? */
condmovestack(L); /* don't change stack (change only for debugging) */
else
luaD_reallocstack(L, goodsize); /* shrink it */
}
void luaD_hook (lua_State *L, int event, int line) {
lua_Hook hook = L->hook;
if (hook && L->allowhook) {
CallInfo *ci = L->ci;
ptrdiff_t top = savestack(L, L->top);
ptrdiff_t ci_top = savestack(L, ci->top);
lua_Debug ar;
ar.event = event;
ar.currentline = line;
ar.i_ci = ci;
luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
ci->top = L->top + LUA_MINSTACK;
lua_assert(ci->top <= L->stack_last);
L->allowhook = 0; /* cannot call hooks inside a hook */
ci->callstatus |= CIST_HOOKED;
lua_unlock(L);
(*hook)(L, &ar);
lua_lock(L);
lua_assert(!L->allowhook);
L->allowhook = 1;
ci->top = restorestack(L, ci_top);
L->top = restorestack(L, top);
ci->callstatus &= ~CIST_HOOKED;
}
}
static void callhook (lua_State *L, CallInfo *ci) {
int hook = LUA_HOOKCALL;
ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */
if (isLua(ci->previous) &&
GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
ci->callstatus |= CIST_TAIL;
hook = LUA_HOOKTAILCALL;
}
luaD_hook(L, hook, -1);
ci->u.l.savedpc--; /* correct 'pc' */
}
static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
int i;
int nfixargs = p->numparams;
StkId base, fixed;
lua_assert(actual >= nfixargs);
/* move fixed parameters to final position */
luaD_checkstack(L, p->maxstacksize); /* check again for new 'base' */
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);
}
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 next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
/*
** returns true if function has been executed (C function)
*/
int luaD_precall (lua_State *L, StkId func, int nresults) {
lua_CFunction f;
CallInfo *ci;
int n; /* number of arguments (Lua) or returns (C) */
ptrdiff_t funcr = savestack(L, func);
switch (ttype(func)) {
case LUA_TLCF: /* light C function */
f = fvalue(func);
goto Cfunc;
case LUA_TCCL: { /* C closure */
f = clCvalue(func)->f;
Cfunc:
luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
ci = next_ci(L); /* now 'enter' new function */
ci->nresults = nresults;
ci->func = restorestack(L, funcr);
ci->top = L->top + LUA_MINSTACK;
lua_assert(ci->top <= L->stack_last);
ci->callstatus = 0;
luaC_checkGC(L); /* stack grow uses memory */
if (L->hookmask & LUA_MASKCALL)
luaD_hook(L, LUA_HOOKCALL, -1);
lua_unlock(L);
n = (*f)(L); /* do the actual call */
lua_lock(L);
api_checknelems(L, n);
luaD_poscall(L, L->top - n);
return 1;
}
case LUA_TLCL: { /* Lua function: prepare its call */
StkId base;
Proto *p = clLvalue(func)->p;
n = cast_int(L->top - func) - 1; /* number of real arguments */
luaD_checkstack(L, p->maxstacksize);
for (; n < p->numparams; n++)
setnilvalue(L->top++); /* complete missing arguments */
if (!p->is_vararg) {
func = restorestack(L, funcr);
base = func + 1;
}
else {
base = adjust_varargs(L, p, n);
func = restorestack(L, funcr); /* previous call can change stack */
}
ci = next_ci(L); /* now 'enter' new function */
ci->nresults = nresults;
ci->func = func;
ci->u.l.base = base;
ci->top = base + p->maxstacksize;
lua_assert(ci->top <= L->stack_last);
ci->u.l.savedpc = p->code; /* starting point */
ci->callstatus = CIST_LUA;
L->top = ci->top;
luaC_checkGC(L); /* stack grow uses memory */
if (L->hookmask & LUA_MASKCALL)
callhook(L, ci);
return 0;
}
default: { /* not a function */
func = tryfuncTM(L, func); /* retry with 'function' tag method */
return luaD_precall(L, func, nresults); /* now it must be a function */
}
}
}
int luaD_poscall (lua_State *L, StkId firstResult) {
StkId res;
int wanted, i;
CallInfo *ci = L->ci;
if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
if (L->hookmask & LUA_MASKRET) {
ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */
luaD_hook(L, LUA_HOOKRET, -1);
firstResult = restorestack(L, fr);
}
L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */
}
res = ci->func; /* res == final position of 1st result */
wanted = ci->nresults;
L->ci = ci = ci->previous; /* back to caller */
/* 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, int allowyield) {
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 (!allowyield) L->nny++;
if (!luaD_precall(L, func, nResults)) /* is a Lua function? */
luaV_execute(L); /* call it */
if (!allowyield) L->nny--;
L->nCcalls--;
}
static void finishCcall (lua_State *L) {
CallInfo *ci = L->ci;
int n;
lua_assert(ci->u.c.k != NULL); /* must have a continuation */
lua_assert(L->nny == 0);
if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */
ci->callstatus &= ~CIST_YPCALL; /* finish 'lua_pcall' */
L->errfunc = ci->u.c.old_errfunc;
}
/* finish 'lua_callk'/'lua_pcall' */
adjustresults(L, ci->nresults);
/* call continuation function */
if (!(ci->callstatus & CIST_STAT)) /* no call status? */
ci->u.c.status = LUA_YIELD; /* 'default' status */
lua_assert(ci->u.c.status != LUA_OK);
ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
lua_unlock(L);
n = (*ci->u.c.k)(L);
lua_lock(L);
api_checknelems(L, n);
/* finish 'luaD_precall' */
luaD_poscall(L, L->top - n);
}
static void unroll (lua_State *L, void *ud) {
UNUSED(ud);
for (;;) {
if (L->ci == &L->base_ci) /* stack is empty? */
return; /* coroutine finished normally */
if (!isLua(L->ci)) /* C function? */
finishCcall(L);
else { /* Lua function */
luaV_finishOp(L); /* finish interrupted instruction */
luaV_execute(L); /* execute down to higher C 'boundary' */
}
}
}
/*
** check whether thread has a suspended protected call
*/
static CallInfo *findpcall (lua_State *L) {
CallInfo *ci;
for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */
if (ci->callstatus & CIST_YPCALL)
return ci;
}
return NULL; /* no pending pcall */
}
static int recover (lua_State *L, int status) {
StkId oldtop;
CallInfo *ci = findpcall(L);
if (ci == NULL) return 0; /* no recovery point */
/* "finish" luaD_pcall */
oldtop = restorestack(L, ci->extra);
luaF_close(L, oldtop);
seterrorobj(L, status, oldtop);
L->ci = ci;
L->allowhook = ci->u.c.old_allowhook;
L->nny = 0; /* should be zero to be yieldable */
luaD_shrinkstack(L);
L->errfunc = ci->u.c.old_errfunc;
ci->callstatus |= CIST_STAT; /* call has error status */
ci->u.c.status = status; /* (here it is) */
return 1; /* continue running the coroutine */
}
/*
** signal an error in the call to 'resume', not in the execution of the
** coroutine itself. (Such errors should not be handled by any coroutine
** error handler and should not kill the coroutine.)
*/
static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) {
L->top = firstArg; /* remove args from the stack */
setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */
api_incr_top(L);
luaD_throw(L, -1); /* jump back to 'lua_resume' */
}
/*
** do the work for 'lua_resume' in protected mode
*/
static void resume (lua_State *L, void *ud) {
int nCcalls = L->nCcalls;
StkId firstArg = cast(StkId, ud);
CallInfo *ci = L->ci;
if (nCcalls >= LUAI_MAXCCALLS)
resume_error(L, "C stack overflow", firstArg);
if (L->status == LUA_OK) { /* may be starting a coroutine */
if (ci != &L->base_ci) /* not in base level? */
resume_error(L, "cannot resume non-suspended coroutine", firstArg);
/* coroutine is in base level; start running it */
if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */
luaV_execute(L); /* call it */
}
else if (L->status != LUA_YIELD)
resume_error(L, "cannot resume dead coroutine", firstArg);
else { /* resuming from previous yield */
L->status = LUA_OK;
ci->func = restorestack(L, ci->extra);
if (isLua(ci)) /* yielded inside a hook? */
luaV_execute(L); /* just continue running Lua code */
else { /* 'common' yield */
if (ci->u.c.k != NULL) { /* does it have a continuation? */
int n;
ci->u.c.status = LUA_YIELD; /* 'default' status */
ci->callstatus |= CIST_YIELDED;
lua_unlock(L);
n = (*ci->u.c.k)(L); /* call continuation */
lua_lock(L);
api_checknelems(L, n);
firstArg = L->top - n; /* yield results come from continuation */
}
luaD_poscall(L, firstArg); /* finish 'luaD_precall' */
}
unroll(L, NULL);
}
lua_assert(nCcalls == L->nCcalls);
}
LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
int status;
int oldnny = L->nny; /* save 'nny' */
lua_lock(L);
luai_userstateresume(L, nargs);
L->nCcalls = (from) ? from->nCcalls + 1 : 1;
L->nny = 0; /* allow yields */
api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
status = luaD_rawrunprotected(L, resume, L->top - nargs);
if (status == -1) /* error calling 'lua_resume'? */
status = LUA_ERRRUN;
else { /* yield or regular error */
while (status != LUA_OK && status != LUA_YIELD) { /* error? */
if (recover(L, status)) /* recover point? */
status = luaD_rawrunprotected(L, unroll, NULL); /* run continuation */
else { /* unrecoverable error */
L->status = cast_byte(status); /* mark thread as `dead' */
seterrorobj(L, status, L->top);
L->ci->top = L->top;
break;
}
}
lua_assert(status == L->status);
}
L->nny = oldnny; /* restore 'nny' */
L->nCcalls--;
lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
lua_unlock(L);
return status;
}
LUA_API int lua_isyieldable (lua_State *L) {
return (L->nny == 0);
}
LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) {
CallInfo *ci = L->ci;
luai_userstateyield(L, nresults);
lua_lock(L);
api_checknelems(L, nresults);
if (L->nny > 0) {
if (L != G(L)->mainthread)
luaG_runerror(L, "attempt to yield across a C-call boundary");
else
luaG_runerror(L, "attempt to yield from outside a coroutine");
}
L->status = LUA_YIELD;
ci->extra = savestack(L, ci->func); /* save current 'func' */
if (isLua(ci)) { /* inside a hook? */
api_check(L, k == NULL, "hooks cannot continue after yielding");
}
else {
if ((ci->u.c.k = k) != NULL) /* is there a continuation? */
ci->u.c.ctx = ctx; /* save context */
ci->func = L->top - nresults - 1; /* protect stack below results */
luaD_throw(L, LUA_YIELD);
}
lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */
lua_unlock(L);
return 0; /* return to 'luaD_hook' */
}
int luaD_pcall (lua_State *L, Pfunc func, void *u,
ptrdiff_t old_top, ptrdiff_t ef) {
int status;
CallInfo *old_ci = L->ci;
lu_byte old_allowhooks = L->allowhook;
unsigned short old_nny = L->nny;
ptrdiff_t old_errfunc = L->errfunc;
L->errfunc = ef;
status = luaD_rawrunprotected(L, func, u);
if (status != LUA_OK) { /* an error occurred? */
StkId oldtop = restorestack(L, old_top);
luaF_close(L, oldtop); /* close possible pending closures */
seterrorobj(L, status, oldtop);
L->ci = old_ci;
L->allowhook = old_allowhooks;
L->nny = old_nny;
luaD_shrinkstack(L);
}
L->errfunc = old_errfunc;
return status;
}
/*
** Execute a protected parser.
*/
struct SParser { /* data to `f_parser' */
ZIO *z;
Mbuffer buff; /* dynamic structure used by the scanner */
Dyndata dyd; /* dynamic structures used by the parser */
const char *mode;
const char *name;
};
static void checkmode (lua_State *L, const char *mode, const char *x) {
if (mode && strchr(mode, x[0]) == NULL) {
luaO_pushfstring(L,
"attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
luaD_throw(L, LUA_ERRSYNTAX);
}
}
static void f_parser (lua_State *L, void *ud) {
Closure *cl;
struct SParser *p = cast(struct SParser *, ud);
int c = zgetc(p->z); /* read first character */
if (c == LUA_SIGNATURE[0]) {
checkmode(L, p->mode, "binary");
cl = luaU_undump(L, p->z, &p->buff, p->name);
}
else {
checkmode(L, p->mode, "text");
cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
}
lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
luaF_initupvals(L, &cl->l);
}
int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
const char *mode) {
struct SParser p;
int status;
L->nny++; /* cannot yield during parsing */
p.z = z; p.name = name; p.mode = mode;
p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
p.dyd.label.arr = NULL; p.dyd.label.size = 0;
luaZ_initbuffer(L, &p.buff);
status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
luaZ_freebuffer(L, &p.buff);
luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
L->nny--;
return status;
}
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