ldo.c
(5.4.6)
/*
** $Id: ldo.c $
** Stack and Call structure of Lua
** See Copyright Notice in lua.h
*/
#define ldo_c
#define LUA_CORE
#include "lprefix.h"
#include <setjmp.h>
#include <stdlib.h>
#include <string.h>
#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"
#define errorstatus(s) ((s) > LUA_YIELD)
/*
** {======================================================
** 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 /* }{ */
/* ISO C 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 */
};
void luaD_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;
}
case LUA_OK: { /* special case only for closing upvalues */
setnilvalue(s2v(oldtop)); /* no error message */
break;
}
default: {
lua_assert(errorstatus(errcode)); /* real error */
setobjs2s(L, oldtop, L->top.p - 1); /* error message on current top */
break;
}
}
L->top.p = 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 */
global_State *g = G(L);
errcode = luaE_resetthread(L, errcode); /* close all upvalues */
if (g->mainthread->errorJmp) { /* main thread has a handler? */
setobjs2s(L, g->mainthread->top.p++, L->top.p - 1); /* copy error obj. */
luaD_throw(g->mainthread, errcode); /* re-throw in main thread */
}
else { /* no handler at all; abort */
if (g->panic) { /* panic function? */
lua_unlock(L);
g->panic(L); /* call panic function (last chance to jump out) */
}
abort();
}
}
}
int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
l_uint32 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;
}
/* }====================================================== */
/*
** {==================================================================
** Stack reallocation
** ===================================================================
*/
/*
** Change all pointers to the stack into offsets.
*/
static void relstack (lua_State *L) {
CallInfo *ci;
UpVal *up;
L->top.offset = savestack(L, L->top.p);
L->tbclist.offset = savestack(L, L->tbclist.p);
for (up = L->openupval; up != NULL; up = up->u.open.next)
up->v.offset = savestack(L, uplevel(up));
for (ci = L->ci; ci != NULL; ci = ci->previous) {
ci->top.offset = savestack(L, ci->top.p);
ci->func.offset = savestack(L, ci->func.p);
}
}
/*
** Change back all offsets into pointers.
*/
static void correctstack (lua_State *L) {
CallInfo *ci;
UpVal *up;
L->top.p = restorestack(L, L->top.offset);
L->tbclist.p = restorestack(L, L->tbclist.offset);
for (up = L->openupval; up != NULL; up = up->u.open.next)
up->v.p = s2v(restorestack(L, up->v.offset));
for (ci = L->ci; ci != NULL; ci = ci->previous) {
ci->top.p = restorestack(L, ci->top.offset);
ci->func.p = restorestack(L, ci->func.offset);
if (isLua(ci))
ci->u.l.trap = 1; /* signal to update 'trap' in 'luaV_execute' */
}
}
/* some space for error handling */
#define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
/*
** Reallocate the stack to a new size, correcting all pointers into it.
** In ISO C, any pointer use after the pointer has been deallocated is
** undefined behavior. So, before the reallocation, all pointers are
** changed to offsets, and after the reallocation they are changed back
** to pointers. As during the reallocation the pointers are invalid, the
** reallocation cannot run emergency collections.
**
** In case of allocation error, raise an error or return false according
** to 'raiseerror'.
*/
int luaD_reallocstack (lua_State *L, int newsize, int raiseerror) {
int oldsize = stacksize(L);
int i;
StkId newstack;
int oldgcstop = G(L)->gcstopem;
lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
relstack(L); /* change pointers to offsets */
G(L)->gcstopem = 1; /* stop emergency collection */
newstack = luaM_reallocvector(L, L->stack.p, oldsize + EXTRA_STACK,
newsize + EXTRA_STACK, StackValue);
G(L)->gcstopem = oldgcstop; /* restore emergency collection */
if (l_unlikely(newstack == NULL)) { /* reallocation failed? */
correctstack(L); /* change offsets back to pointers */
if (raiseerror)
luaM_error(L);
else return 0; /* do not raise an error */
}
L->stack.p = newstack;
correctstack(L); /* change offsets back to pointers */
L->stack_last.p = L->stack.p + newsize;
for (i = oldsize + EXTRA_STACK; i < newsize + EXTRA_STACK; i++)
setnilvalue(s2v(newstack + i)); /* erase new segment */
return 1;
}
/*
** Try to grow the stack by at least 'n' elements. When 'raiseerror'
** is true, raises any error; otherwise, return 0 in case of errors.
*/
int luaD_growstack (lua_State *L, int n, int raiseerror) {
int size = stacksize(L);
if (l_unlikely(size > LUAI_MAXSTACK)) {
/* if stack is larger than maximum, thread is already using the
extra space reserved for errors, that is, thread is handling
a stack error; cannot grow further than that. */
lua_assert(stacksize(L) == ERRORSTACKSIZE);
if (raiseerror)
luaD_throw(L, LUA_ERRERR); /* error inside message handler */
return 0; /* if not 'raiseerror', just signal it */
}
else if (n < LUAI_MAXSTACK) { /* avoids arithmetic overflows */
int newsize = 2 * size; /* tentative new size */
int needed = cast_int(L->top.p - L->stack.p) + n;
if (newsize > LUAI_MAXSTACK) /* cannot cross the limit */
newsize = LUAI_MAXSTACK;
if (newsize < needed) /* but must respect what was asked for */
newsize = needed;
if (l_likely(newsize <= LUAI_MAXSTACK))
return luaD_reallocstack(L, newsize, raiseerror);
}
/* else stack overflow */
/* add extra size to be able to handle the error message */
luaD_reallocstack(L, ERRORSTACKSIZE, raiseerror);
if (raiseerror)
luaG_runerror(L, "stack overflow");
return 0;
}
/*
** Compute how much of the stack is being used, by computing the
** maximum top of all call frames in the stack and the current top.
*/
static int stackinuse (lua_State *L) {
CallInfo *ci;
int res;
StkId lim = L->top.p;
for (ci = L->ci; ci != NULL; ci = ci->previous) {
if (lim < ci->top.p) lim = ci->top.p;
}
lua_assert(lim <= L->stack_last.p + EXTRA_STACK);
res = cast_int(lim - L->stack.p) + 1; /* part of stack in use */
if (res < LUA_MINSTACK)
res = LUA_MINSTACK; /* ensure a minimum size */
return res;
}
/*
** If stack size is more than 3 times the current use, reduce that size
** to twice the current use. (So, the final stack size is at most 2/3 the
** previous size, and half of its entries are empty.)
** As a particular case, if stack was handling a stack overflow and now
** it is not, 'max' (limited by LUAI_MAXSTACK) will be smaller than
** stacksize (equal to ERRORSTACKSIZE in this case), and so the stack
** will be reduced to a "regular" size.
*/
void luaD_shrinkstack (lua_State *L) {
int inuse = stackinuse(L);
int max = (inuse > LUAI_MAXSTACK / 3) ? LUAI_MAXSTACK : inuse * 3;
/* if thread is currently not handling a stack overflow and its
size is larger than maximum "reasonable" size, shrink it */
if (inuse <= LUAI_MAXSTACK && stacksize(L) > max) {
int nsize = (inuse > LUAI_MAXSTACK / 2) ? LUAI_MAXSTACK : inuse * 2;
luaD_reallocstack(L, nsize, 0); /* ok if that fails */
}
else /* don't change stack */
condmovestack(L,{},{}); /* (change only for debugging) */
luaE_shrinkCI(L); /* shrink CI list */
}
void luaD_inctop (lua_State *L) {
luaD_checkstack(L, 1);
L->top.p++;
}
/* }================================================================== */
/*
** Call a hook for the given event. Make sure there is a hook to be
** called. (Both 'L->hook' and 'L->hookmask', which trigger this
** function, can be changed asynchronously by signals.)
*/
void luaD_hook (lua_State *L, int event, int line,
int ftransfer, int ntransfer) {
lua_Hook hook = L->hook;
if (hook && L->allowhook) { /* make sure there is a hook */
int mask = CIST_HOOKED;
CallInfo *ci = L->ci;
ptrdiff_t top = savestack(L, L->top.p); /* preserve original 'top' */
ptrdiff_t ci_top = savestack(L, ci->top.p); /* idem for 'ci->top' */
lua_Debug ar;
ar.event = event;
ar.currentline = line;
ar.i_ci = ci;
if (ntransfer != 0) {
mask |= CIST_TRAN; /* 'ci' has transfer information */
ci->u2.transferinfo.ftransfer = ftransfer;
ci->u2.transferinfo.ntransfer = ntransfer;
}
if (isLua(ci) && L->top.p < ci->top.p)
L->top.p = ci->top.p; /* protect entire activation register */
luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
if (ci->top.p < L->top.p + LUA_MINSTACK)
ci->top.p = L->top.p + LUA_MINSTACK;
L->allowhook = 0; /* cannot call hooks inside a hook */
ci->callstatus |= mask;
lua_unlock(L);
(*hook)(L, &ar);
lua_lock(L);
lua_assert(!L->allowhook);
L->allowhook = 1;
ci->top.p = restorestack(L, ci_top);
L->top.p = restorestack(L, top);
ci->callstatus &= ~mask;
}
}
/*
** Executes a call hook for Lua functions. This function is called
** whenever 'hookmask' is not zero, so it checks whether call hooks are
** active.
*/
void luaD_hookcall (lua_State *L, CallInfo *ci) {
L->oldpc = 0; /* set 'oldpc' for new function */
if (L->hookmask & LUA_MASKCALL) { /* is call hook on? */
int event = (ci->callstatus & CIST_TAIL) ? LUA_HOOKTAILCALL
: LUA_HOOKCALL;
Proto *p = ci_func(ci)->p;
ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */
luaD_hook(L, event, -1, 1, p->numparams);
ci->u.l.savedpc--; /* correct 'pc' */
}
}
/*
** Executes a return hook for Lua and C functions and sets/corrects
** 'oldpc'. (Note that this correction is needed by the line hook, so it
** is done even when return hooks are off.)
*/
static void rethook (lua_State *L, CallInfo *ci, int nres) {
if (L->hookmask & LUA_MASKRET) { /* is return hook on? */
StkId firstres = L->top.p - nres; /* index of first result */
int delta = 0; /* correction for vararg functions */
int ftransfer;
if (isLua(ci)) {
Proto *p = ci_func(ci)->p;
if (p->is_vararg)
delta = ci->u.l.nextraargs + p->numparams + 1;
}
ci->func.p += delta; /* if vararg, back to virtual 'func' */
ftransfer = cast(unsigned short, firstres - ci->func.p);
luaD_hook(L, LUA_HOOKRET, -1, ftransfer, nres); /* call it */
ci->func.p -= delta;
}
if (isLua(ci = ci->previous))
L->oldpc = pcRel(ci->u.l.savedpc, ci_func(ci)->p); /* set 'oldpc' */
}
/*
** Check whether 'func' has a '__call' metafield. If so, put it in the
** stack, below original 'func', so that 'luaD_precall' can call it. Raise
** an error if there is no '__call' metafield.
*/
StkId luaD_tryfuncTM (lua_State *L, StkId func) {
const TValue *tm;
StkId p;
checkstackGCp(L, 1, func); /* space for metamethod */
tm = luaT_gettmbyobj(L, s2v(func), TM_CALL); /* (after previous GC) */
if (l_unlikely(ttisnil(tm)))
luaG_callerror(L, s2v(func)); /* nothing to call */
for (p = L->top.p; p > func; p--) /* open space for metamethod */
setobjs2s(L, p, p-1);
L->top.p++; /* stack space pre-allocated by the caller */
setobj2s(L, func, tm); /* metamethod is the new function to be called */
return func;
}
/*
** Given 'nres' results at 'firstResult', move 'wanted' of them to 'res'.
** Handle most typical cases (zero results for commands, one result for
** expressions, multiple results for tail calls/single parameters)
** separated.
*/
l_sinline void moveresults (lua_State *L, StkId res, int nres, int wanted) {
StkId firstresult;
int i;
switch (wanted) { /* handle typical cases separately */
case 0: /* no values needed */
L->top.p = res;
return;
case 1: /* one value needed */
if (nres == 0) /* no results? */
setnilvalue(s2v(res)); /* adjust with nil */
else /* at least one result */
setobjs2s(L, res, L->top.p - nres); /* move it to proper place */
L->top.p = res + 1;
return;
case LUA_MULTRET:
wanted = nres; /* we want all results */
break;
default: /* two/more results and/or to-be-closed variables */
if (hastocloseCfunc(wanted)) { /* to-be-closed variables? */
L->ci->callstatus |= CIST_CLSRET; /* in case of yields */
L->ci->u2.nres = nres;
res = luaF_close(L, res, CLOSEKTOP, 1);
L->ci->callstatus &= ~CIST_CLSRET;
if (L->hookmask) { /* if needed, call hook after '__close's */
ptrdiff_t savedres = savestack(L, res);
rethook(L, L->ci, nres);
res = restorestack(L, savedres); /* hook can move stack */
}
wanted = decodeNresults(wanted);
if (wanted == LUA_MULTRET)
wanted = nres; /* we want all results */
}
break;
}
/* generic case */
firstresult = L->top.p - nres; /* index of first result */
if (nres > wanted) /* extra results? */
nres = wanted; /* don't need them */
for (i = 0; i < nres; i++) /* move all results to correct place */
setobjs2s(L, res + i, firstresult + i);
for (; i < wanted; i++) /* complete wanted number of results */
setnilvalue(s2v(res + i));
L->top.p = res + wanted; /* top points after the last result */
}
/*
** Finishes a function call: calls hook if necessary, moves current
** number of results to proper place, and returns to previous call
** info. If function has to close variables, hook must be called after
** that.
*/
void luaD_poscall (lua_State *L, CallInfo *ci, int nres) {
int wanted = ci->nresults;
if (l_unlikely(L->hookmask && !hastocloseCfunc(wanted)))
rethook(L, ci, nres);
/* move results to proper place */
moveresults(L, ci->func.p, nres, wanted);
/* function cannot be in any of these cases when returning */
lua_assert(!(ci->callstatus &
(CIST_HOOKED | CIST_YPCALL | CIST_FIN | CIST_TRAN | CIST_CLSRET)));
L->ci = ci->previous; /* back to caller (after closing variables) */
}
#define next_ci(L) (L->ci->next ? L->ci->next : luaE_extendCI(L))
l_sinline CallInfo *prepCallInfo (lua_State *L, StkId func, int nret,
int mask, StkId top) {
CallInfo *ci = L->ci = next_ci(L); /* new frame */
ci->func.p = func;
ci->nresults = nret;
ci->callstatus = mask;
ci->top.p = top;
return ci;
}
/*
** precall for C functions
*/
l_sinline int precallC (lua_State *L, StkId func, int nresults,
lua_CFunction f) {
int n; /* number of returns */
CallInfo *ci;
checkstackGCp(L, LUA_MINSTACK, func); /* ensure minimum stack size */
L->ci = ci = prepCallInfo(L, func, nresults, CIST_C,
L->top.p + LUA_MINSTACK);
lua_assert(ci->top.p <= L->stack_last.p);
if (l_unlikely(L->hookmask & LUA_MASKCALL)) {
int narg = cast_int(L->top.p - func) - 1;
luaD_hook(L, LUA_HOOKCALL, -1, 1, narg);
}
lua_unlock(L);
n = (*f)(L); /* do the actual call */
lua_lock(L);
api_checknelems(L, n);
luaD_poscall(L, ci, n);
return n;
}
/*
** Prepare a function for a tail call, building its call info on top
** of the current call info. 'narg1' is the number of arguments plus 1
** (so that it includes the function itself). Return the number of
** results, if it was a C function, or -1 for a Lua function.
*/
int luaD_pretailcall (lua_State *L, CallInfo *ci, StkId func,
int narg1, int delta) {
retry:
switch (ttypetag(s2v(func))) {
case LUA_VCCL: /* C closure */
return precallC(L, func, LUA_MULTRET, clCvalue(s2v(func))->f);
case LUA_VLCF: /* light C function */
return precallC(L, func, LUA_MULTRET, fvalue(s2v(func)));
case LUA_VLCL: { /* Lua function */
Proto *p = clLvalue(s2v(func))->p;
int fsize = p->maxstacksize; /* frame size */
int nfixparams = p->numparams;
int i;
checkstackGCp(L, fsize - delta, func);
ci->func.p -= delta; /* restore 'func' (if vararg) */
for (i = 0; i < narg1; i++) /* move down function and arguments */
setobjs2s(L, ci->func.p + i, func + i);
func = ci->func.p; /* moved-down function */
for (; narg1 <= nfixparams; narg1++)
setnilvalue(s2v(func + narg1)); /* complete missing arguments */
ci->top.p = func + 1 + fsize; /* top for new function */
lua_assert(ci->top.p <= L->stack_last.p);
ci->u.l.savedpc = p->code; /* starting point */
ci->callstatus |= CIST_TAIL;
L->top.p = func + narg1; /* set top */
return -1;
}
default: { /* not a function */
func = luaD_tryfuncTM(L, func); /* try to get '__call' metamethod */
/* return luaD_pretailcall(L, ci, func, narg1 + 1, delta); */
narg1++;
goto retry; /* try again */
}
}
}
/*
** Prepares the call to a function (C or Lua). For C functions, also do
** the call. The function to be called is at '*func'. The arguments
** are on the stack, right after the function. Returns the CallInfo
** to be executed, if it was a Lua function. Otherwise (a C function)
** returns NULL, with all the results on the stack, starting at the
** original function position.
*/
CallInfo *luaD_precall (lua_State *L, StkId func, int nresults) {
retry:
switch (ttypetag(s2v(func))) {
case LUA_VCCL: /* C closure */
precallC(L, func, nresults, clCvalue(s2v(func))->f);
return NULL;
case LUA_VLCF: /* light C function */
precallC(L, func, nresults, fvalue(s2v(func)));
return NULL;
case LUA_VLCL: { /* Lua function */
CallInfo *ci;
Proto *p = clLvalue(s2v(func))->p;
int narg = cast_int(L->top.p - func) - 1; /* number of real arguments */
int nfixparams = p->numparams;
int fsize = p->maxstacksize; /* frame size */
checkstackGCp(L, fsize, func);
L->ci = ci = prepCallInfo(L, func, nresults, 0, func + 1 + fsize);
ci->u.l.savedpc = p->code; /* starting point */
for (; narg < nfixparams; narg++)
setnilvalue(s2v(L->top.p++)); /* complete missing arguments */
lua_assert(ci->top.p <= L->stack_last.p);
return ci;
}
default: { /* not a function */
func = luaD_tryfuncTM(L, func); /* try to get '__call' metamethod */
/* return luaD_precall(L, func, nresults); */
goto retry; /* try again with metamethod */
}
}
}
/*
** Call a function (C or Lua) through C. 'inc' can be 1 (increment
** number of recursive invocations in the C stack) or nyci (the same
** plus increment number of non-yieldable calls).
** This function can be called with some use of EXTRA_STACK, so it should
** check the stack before doing anything else. 'luaD_precall' already
** does that.
*/
l_sinline void ccall (lua_State *L, StkId func, int nResults, l_uint32 inc) {
CallInfo *ci;
L->nCcalls += inc;
if (l_unlikely(getCcalls(L) >= LUAI_MAXCCALLS)) {
checkstackp(L, 0, func); /* free any use of EXTRA_STACK */
luaE_checkcstack(L);
}
if ((ci = luaD_precall(L, func, nResults)) != NULL) { /* Lua function? */
ci->callstatus = CIST_FRESH; /* mark that it is a "fresh" execute */
luaV_execute(L, ci); /* call it */
}
L->nCcalls -= inc;
}
/*
** External interface for 'ccall'
*/
void luaD_call (lua_State *L, StkId func, int nResults) {
ccall(L, func, nResults, 1);
}
/*
** Similar to 'luaD_call', but does not allow yields during the call.
*/
void luaD_callnoyield (lua_State *L, StkId func, int nResults) {
ccall(L, func, nResults, nyci);
}
/*
** Finish the job of 'lua_pcallk' after it was interrupted by an yield.
** (The caller, 'finishCcall', does the final call to 'adjustresults'.)
** The main job is to complete the 'luaD_pcall' called by 'lua_pcallk'.
** If a '__close' method yields here, eventually control will be back
** to 'finishCcall' (when that '__close' method finally returns) and
** 'finishpcallk' will run again and close any still pending '__close'
** methods. Similarly, if a '__close' method errs, 'precover' calls
** 'unroll' which calls ''finishCcall' and we are back here again, to
** close any pending '__close' methods.
** Note that, up to the call to 'luaF_close', the corresponding
** 'CallInfo' is not modified, so that this repeated run works like the
** first one (except that it has at least one less '__close' to do). In
** particular, field CIST_RECST preserves the error status across these
** multiple runs, changing only if there is a new error.
*/
static int finishpcallk (lua_State *L, CallInfo *ci) {
int status = getcistrecst(ci); /* get original status */
if (l_likely(status == LUA_OK)) /* no error? */
status = LUA_YIELD; /* was interrupted by an yield */
else { /* error */
StkId func = restorestack(L, ci->u2.funcidx);
L->allowhook = getoah(ci->callstatus); /* restore 'allowhook' */
func = luaF_close(L, func, status, 1); /* can yield or raise an error */
luaD_seterrorobj(L, status, func);
luaD_shrinkstack(L); /* restore stack size in case of overflow */
setcistrecst(ci, LUA_OK); /* clear original status */
}
ci->callstatus &= ~CIST_YPCALL;
L->errfunc = ci->u.c.old_errfunc;
/* if it is here, there were errors or yields; unlike 'lua_pcallk',
do not change status */
return status;
}
/*
** Completes the execution of a C function interrupted by an yield.
** The interruption must have happened while the function was either
** closing its tbc variables in 'moveresults' or executing
** 'lua_callk'/'lua_pcallk'. In the first case, it just redoes
** 'luaD_poscall'. In the second case, the call to 'finishpcallk'
** finishes the interrupted execution of 'lua_pcallk'. After that, it
** calls the continuation of the interrupted function and finally it
** completes the job of the 'luaD_call' that called the function. In
** the call to 'adjustresults', we do not know the number of results
** of the function called by 'lua_callk'/'lua_pcallk', so we are
** conservative and use LUA_MULTRET (always adjust).
*/
static void finishCcall (lua_State *L, CallInfo *ci) {
int n; /* actual number of results from C function */
if (ci->callstatus & CIST_CLSRET) { /* was returning? */
lua_assert(hastocloseCfunc(ci->nresults));
n = ci->u2.nres; /* just redo 'luaD_poscall' */
/* don't need to reset CIST_CLSRET, as it will be set again anyway */
}
else {
int status = LUA_YIELD; /* default if there were no errors */
/* must have a continuation and must be able to call it */
lua_assert(ci->u.c.k != NULL && yieldable(L));
if (ci->callstatus & CIST_YPCALL) /* was inside a 'lua_pcallk'? */
status = finishpcallk(L, ci); /* finish it */
adjustresults(L, LUA_MULTRET); /* finish 'lua_callk' */
lua_unlock(L);
n = (*ci->u.c.k)(L, status, ci->u.c.ctx); /* call continuation */
lua_lock(L);
api_checknelems(L, n);
}
luaD_poscall(L, ci, n); /* finish 'luaD_call' */
}
/*
** Executes "full continuation" (everything in the stack) of a
** previously interrupted coroutine until the stack is empty (or another
** interruption long-jumps out of the loop).
*/
static void unroll (lua_State *L, void *ud) {
CallInfo *ci;
UNUSED(ud);
while ((ci = L->ci) != &L->base_ci) { /* something in the stack */
if (!isLua(ci)) /* C function? */
finishCcall(L, ci); /* complete its execution */
else { /* Lua function */
luaV_finishOp(L); /* finish interrupted instruction */
luaV_execute(L, ci); /* execute down to higher C 'boundary' */
}
}
}
/*
** Try to find a suspended protected call (a "recover point") for the
** given thread.
*/
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 */
}
/*
** Signal an error in the call to 'lua_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 int resume_error (lua_State *L, const char *msg, int narg) {
L->top.p -= narg; /* remove args from the stack */
setsvalue2s(L, L->top.p, luaS_new(L, msg)); /* push error message */
api_incr_top(L);
lua_unlock(L);
return LUA_ERRRUN;
}
/*
** Do the work for 'lua_resume' in protected mode. Most of the work
** depends on the status of the coroutine: initial state, suspended
** inside a hook, or regularly suspended (optionally with a continuation
** function), plus erroneous cases: non-suspended coroutine or dead
** coroutine.
*/
static void resume (lua_State *L, void *ud) {
int n = *(cast(int*, ud)); /* number of arguments */
StkId firstArg = L->top.p - n; /* first argument */
CallInfo *ci = L->ci;
if (L->status == LUA_OK) /* starting a coroutine? */
ccall(L, firstArg - 1, LUA_MULTRET, 0); /* just call its body */
else { /* resuming from previous yield */
lua_assert(L->status == LUA_YIELD);
L->status = LUA_OK; /* mark that it is running (again) */
if (isLua(ci)) { /* yielded inside a hook? */
L->top.p = firstArg; /* discard arguments */
luaV_execute(L, ci); /* just continue running Lua code */
}
else { /* 'common' yield */
if (ci->u.c.k != NULL) { /* does it have a continuation function? */
lua_unlock(L);
n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */
lua_lock(L);
api_checknelems(L, n);
}
luaD_poscall(L, ci, n); /* finish 'luaD_call' */
}
unroll(L, NULL); /* run continuation */
}
}
/*
** Unrolls a coroutine in protected mode while there are recoverable
** errors, that is, errors inside a protected call. (Any error
** interrupts 'unroll', and this loop protects it again so it can
** continue.) Stops with a normal end (status == LUA_OK), an yield
** (status == LUA_YIELD), or an unprotected error ('findpcall' doesn't
** find a recover point).
*/
static int precover (lua_State *L, int status) {
CallInfo *ci;
while (errorstatus(status) && (ci = findpcall(L)) != NULL) {
L->ci = ci; /* go down to recovery functions */
setcistrecst(ci, status); /* status to finish 'pcall' */
status = luaD_rawrunprotected(L, unroll, NULL);
}
return status;
}
LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs,
int *nresults) {
int status;
lua_lock(L);
if (L->status == LUA_OK) { /* may be starting a coroutine */
if (L->ci != &L->base_ci) /* not in base level? */
return resume_error(L, "cannot resume non-suspended coroutine", nargs);
else if (L->top.p - (L->ci->func.p + 1) == nargs) /* no function? */
return resume_error(L, "cannot resume dead coroutine", nargs);
}
else if (L->status != LUA_YIELD) /* ended with errors? */
return resume_error(L, "cannot resume dead coroutine", nargs);
L->nCcalls = (from) ? getCcalls(from) : 0;
if (getCcalls(L) >= LUAI_MAXCCALLS)
return resume_error(L, "C stack overflow", nargs);
L->nCcalls++;
luai_userstateresume(L, nargs);
api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
status = luaD_rawrunprotected(L, resume, &nargs);
/* continue running after recoverable errors */
status = precover(L, status);
if (l_likely(!errorstatus(status)))
lua_assert(status == L->status); /* normal end or yield */
else { /* unrecoverable error */
L->status = cast_byte(status); /* mark thread as 'dead' */
luaD_seterrorobj(L, status, L->top.p); /* push error message */
L->ci->top.p = L->top.p;
}
*nresults = (status == LUA_YIELD) ? L->ci->u2.nyield
: cast_int(L->top.p - (L->ci->func.p + 1));
lua_unlock(L);
return status;
}
LUA_API int lua_isyieldable (lua_State *L) {
return yieldable(L);
}
LUA_API int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx,
lua_KFunction k) {
CallInfo *ci;
luai_userstateyield(L, nresults);
lua_lock(L);
ci = L->ci;
api_checknelems(L, nresults);
if (l_unlikely(!yieldable(L))) {
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->u2.nyield = nresults; /* save number of results */
if (isLua(ci)) { /* inside a hook? */
lua_assert(!isLuacode(ci));
api_check(L, nresults == 0, "hooks cannot yield values");
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 */
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' */
}
/*
** Auxiliary structure to call 'luaF_close' in protected mode.
*/
struct CloseP {
StkId level;
int status;
};
/*
** Auxiliary function to call 'luaF_close' in protected mode.
*/
static void closepaux (lua_State *L, void *ud) {
struct CloseP *pcl = cast(struct CloseP *, ud);
luaF_close(L, pcl->level, pcl->status, 0);
}
/*
** Calls 'luaF_close' in protected mode. Return the original status
** or, in case of errors, the new status.
*/
int luaD_closeprotected (lua_State *L, ptrdiff_t level, int status) {
CallInfo *old_ci = L->ci;
lu_byte old_allowhooks = L->allowhook;
for (;;) { /* keep closing upvalues until no more errors */
struct CloseP pcl;
pcl.level = restorestack(L, level); pcl.status = status;
status = luaD_rawrunprotected(L, &closepaux, &pcl);
if (l_likely(status == LUA_OK)) /* no more errors? */
return pcl.status;
else { /* an error occurred; restore saved state and repeat */
L->ci = old_ci;
L->allowhook = old_allowhooks;
}
}
}
/*
** Call the C function 'func' in protected mode, restoring basic
** thread information ('allowhook', etc.) and in particular
** its stack level in case of errors.
*/
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;
ptrdiff_t old_errfunc = L->errfunc;
L->errfunc = ef;
status = luaD_rawrunprotected(L, func, u);
if (l_unlikely(status != LUA_OK)) { /* an error occurred? */
L->ci = old_ci;
L->allowhook = old_allowhooks;
status = luaD_closeprotected(L, old_top, status);
luaD_seterrorobj(L, status, restorestack(L, old_top));
luaD_shrinkstack(L); /* restore stack size in case of overflow */
}
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 '%s')", x, mode);
luaD_throw(L, LUA_ERRSYNTAX);
}
}
static void f_parser (lua_State *L, void *ud) {
LClosure *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->name);
}
else {
checkmode(L, p->mode, "text");
cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
}
lua_assert(cl->nupvalues == cl->p->sizeupvalues);
luaF_initupvals(L, cl);
}
int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
const char *mode) {
struct SParser p;
int status;
incnny(L); /* 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.p), 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);
decnny(L);
return status;
}