Mesen-SX/Lua/ldebug.c

/*
** $Id: ldebug.c,v 2.121 2016/10/19 12:32:10 roberto Exp $
** Debug Interface
** See Copyright Notice in lua.h
*/

#define ldebug_c
#define LUA_CORE

#include "lprefix.h"


#include <stdarg.h>
#include <stddef.h>
#include <string.h>

#include "lua.h"

#include "lapi.h"
#include "lcode.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lvm.h"


#define noLuaClosure(f)		((f) == NULL || (f)->c.tt == LUA_TCCL)


/* Active Lua function (given call info) */
#define ci_func(ci)		(clLvalue((ci)->func))


static const char* funcnamefromcode(lua_State* L, CallInfo* ci,
                                    const char** name);


static int currentpc(CallInfo* ci)
{
	lua_assert(isLua(ci));
	return pcRel(ci->u.l.savedpc, ci_func(ci)->p);
}


static int currentline(CallInfo* ci)
{
	return getfuncline(ci_func(ci)->p, currentpc(ci));
}


/*
** If function yielded, its 'func' can be in the 'extra' field. The
** next function restores 'func' to its correct value for debugging
** purposes. (It exchanges 'func' and 'extra'; so, when called again,
** after debugging, it also "re-restores" ** 'func' to its altered value.
*/
static void swapextra(lua_State* L)
{
	if (L->status == LUA_YIELD)
	{
		CallInfo* ci = L->ci; /* get function that yielded */
		StkId temp = ci->func; /* exchange its 'func' and 'extra' values */
		ci->func = restorestack(L, ci->extra);
		ci->extra = savestack(L, temp);
	}
}


/*
** This function can be called asynchronously (e.g. during a signal).
** Fields 'oldpc', 'basehookcount', and 'hookcount' (set by
** 'resethookcount') are for debug only, and it is no problem if they
** get arbitrary values (causes at most one wrong hook call). 'hookmask'
** is an atomic value. We assume that pointers are atomic too (e.g., gcc
** ensures that for all platforms where it runs). Moreover, 'hook' is
** always checked before being called (see 'luaD_hook').
*/
LUA_API void lua_sethook(lua_State* L, lua_Hook func, int mask, int count)
{
	if (func == NULL || mask == 0)
	{
		/* turn off hooks? */
		mask = 0;
		func = NULL;
	}
	if (isLua(L->ci))
		L->oldpc = L->ci->u.l.savedpc;
	L->hook = func;
	L->basehookcount = count;
	resethookcount(L);
	L->hookmask = cast_byte(mask);
}


LUA_API lua_Hook lua_gethook(lua_State* L)
{
	return L->hook;
}


LUA_API int lua_gethookmask(lua_State* L)
{
	return L->hookmask;
}


LUA_API int lua_gethookcount(lua_State* L)
{
	return L->basehookcount;
}


LUA_API int lua_getstack(lua_State* L, int level, lua_Debug* ar)
{
	int status;
	CallInfo* ci;
	if (level < 0) return 0; /* invalid (negative) level */
	lua_lock(L);
	for (ci = L->ci; level > 0 && ci != &L->base_ci; ci = ci->previous)
		level--;
	if (level == 0 && ci != &L->base_ci)
	{
		/* level found? */
		status = 1;
		ar->i_ci = ci;
	}
	else status = 0; /* no such level */
	lua_unlock(L);
	return status;
}


static const char* upvalname(Proto* p, int uv)
{
	TString* s = check_exp(uv < p->sizeupvalues, p->upvalues[uv].name);
	if (s == NULL) return "?";
	else return getstr(s);
}


static const char* findvararg(CallInfo* ci, int n, StkId* pos)
{
	int nparams = clLvalue(ci->func)->p->numparams;
	if (n >= cast_int(ci->u.l.base - ci->func) - nparams)
		return NULL; /* no such vararg */
	else
	{
		*pos = ci->func + nparams + n;
		return "(*vararg)"; /* generic name for any vararg */
	}
}


static const char* findlocal(lua_State* L, CallInfo* ci, int n,
                             StkId* pos)
{
	const char* name = NULL;
	StkId base;
	if (isLua(ci))
	{
		if (n < 0) /* access to vararg values? */
			return findvararg(ci, -n, pos);
		else
		{
			base = ci->u.l.base;
			name = luaF_getlocalname(ci_func(ci)->p, n, currentpc(ci));
		}
	}
	else
		base = ci->func + 1;
	if (name == NULL)
	{
		/* no 'standard' name? */
		StkId limit = (ci == L->ci) ? L->top : ci->next->func;
		if (limit - base >= n && n > 0) /* is 'n' inside 'ci' stack? */
			name = "(*temporary)"; /* generic name for any valid slot */
		else
			return NULL; /* no name */
	}
	*pos = base + (n - 1);
	return name;
}


LUA_API const char* lua_getlocal(lua_State* L, const lua_Debug* ar, int n)
{
	const char* name;
	lua_lock(L);
	swapextra(L);
	if (ar == NULL)
	{
		/* information about non-active function? */
		if (!isLfunction(L->top - 1)) /* not a Lua function? */
			name = NULL;
		else /* consider live variables at function start (parameters) */
			name = luaF_getlocalname(clLvalue(L->top - 1)->p, n, 0);
	}
	else
	{
		/* active function; get information through 'ar' */
		StkId pos = NULL; /* to avoid warnings */
		name = findlocal(L, ar->i_ci, n, &pos);
		if (name)
		{
			setobj2s(L, L->top, pos);
			api_incr_top(L);
		}
	}
	swapextra(L);
	lua_unlock(L);
	return name;
}


LUA_API const char* lua_setlocal(lua_State* L, const lua_Debug* ar, int n)
{
	StkId pos = NULL; /* to avoid warnings */
	const char* name;
	lua_lock(L);
	swapextra(L);
	name = findlocal(L, ar->i_ci, n, &pos);
	if (name)
	{
		setobjs2s(L, pos, L->top - 1);
		L->top--; /* pop value */
	}
	swapextra(L);
	lua_unlock(L);
	return name;
}


static void funcinfo(lua_Debug* ar, Closure* cl)
{
	if (noLuaClosure(cl))
	{
		ar->source = "=[C]";
		ar->linedefined = -1;
		ar->lastlinedefined = -1;
		ar->what = "C";
	}
	else
	{
		Proto* p = cl->l.p;
		ar->source = p->source ? getstr(p->source) : "=?";
		ar->linedefined = p->linedefined;
		ar->lastlinedefined = p->lastlinedefined;
		ar->what = (ar->linedefined == 0) ? "main" : "Lua";
	}
	luaO_chunkid(ar->short_src, ar->source, LUA_IDSIZE);
}


static void collectvalidlines(lua_State* L, Closure* f)
{
	if (noLuaClosure(f))
	{
		setnilvalue(L->top);
		api_incr_top(L);
	}
	else
	{
		int i;
		TValue v;
		int* lineinfo = f->l.p->lineinfo;
		Table* t = luaH_new(L); /* new table to store active lines */
		sethvalue(L, L->top, t); /* push it on stack */
		api_incr_top(L);
		setbvalue(&v, 1); /* boolean 'true' to be the value of all indices */
		for (i = 0; i < f->l.p->sizelineinfo; i++) /* for all lines with code */
			luaH_setint(L, t, lineinfo[i], &v); /* table[line] = true */
	}
}


static const char* getfuncname(lua_State* L, CallInfo* ci, const char** name)
{
	if (ci == NULL) /* no 'ci'? */
		return NULL; /* no info */
	else if (ci->callstatus & CIST_FIN)
	{
		/* is this a finalizer? */
		*name = "__gc";
		return "metamethod"; /* report it as such */
	}
		/* calling function is a known Lua function? */
	else if (!(ci->callstatus & CIST_TAIL) && isLua(ci->previous))
		return funcnamefromcode(L, ci->previous, name);
	else return NULL; /* no way to find a name */
}


static int auxgetinfo(lua_State* L, const char* what, lua_Debug* ar,
                      Closure* f, CallInfo* ci)
{
	int status = 1;
	for (; *what; what++)
	{
		switch (*what)
		{
		case 'S':
			{
				funcinfo(ar, f);
				break;
			}
		case 'l':
			{
				ar->currentline = (ci && isLua(ci)) ? currentline(ci) : -1;
				break;
			}
		case 'u':
			{
				ar->nups = (f == NULL) ? 0 : f->c.nupvalues;
				if (noLuaClosure(f))
				{
					ar->isvararg = 1;
					ar->nparams = 0;
				}
				else
				{
					ar->isvararg = f->l.p->is_vararg;
					ar->nparams = f->l.p->numparams;
				}
				break;
			}
		case 't':
			{
				ar->istailcall = (ci) ? ci->callstatus & CIST_TAIL : 0;
				break;
			}
		case 'n':
			{
				ar->namewhat = getfuncname(L, ci, &ar->name);
				if (ar->namewhat == NULL)
				{
					ar->namewhat = ""; /* not found */
					ar->name = NULL;
				}
				break;
			}
		case 'L':
		case 'f': /* handled by lua_getinfo */
			break;
		default: status = 0; /* invalid option */
		}
	}
	return status;
}


LUA_API int lua_getinfo(lua_State* L, const char* what, lua_Debug* ar)
{
	int status;
	Closure* cl;
	CallInfo* ci;
	StkId func;
	lua_lock(L);
	swapextra(L);
	if (*what == '>')
	{
		ci = NULL;
		func = L->top - 1;
		api_check(L, ttisfunction(func), "function expected");
		what++; /* skip the '>' */
		L->top--; /* pop function */
	}
	else
	{
		ci = ar->i_ci;
		func = ci->func;
		lua_assert(ttisfunction(ci->func));
	}
	cl = ttisclosure(func) ? clvalue(func) : NULL;
	status = auxgetinfo(L, what, ar, cl, ci);
	if (strchr(what, 'f'))
	{
		setobjs2s(L, L->top, func);
		api_incr_top(L);
	}
	swapextra(L); /* correct before option 'L', which can raise a mem. error */
	if (strchr(what, 'L'))
		collectvalidlines(L, cl);
	lua_unlock(L);
	return status;
}


/*
** {======================================================
** Symbolic Execution
** =======================================================
*/

static const char* getobjname(Proto* p, int lastpc, int reg,
                              const char** name);


/*
** find a "name" for the RK value 'c'
*/
static void kname(Proto* p, int pc, int c, const char** name)
{
	if (ISK(c))
	{
		/* is 'c' a constant? */
		TValue* kvalue = &p->k[INDEXK(c)];
		if (ttisstring(kvalue))
		{
			/* literal constant? */
			*name = svalue(kvalue); /* it is its own name */
			return;
		}
		/* else no reasonable name found */
	}
	else
	{
		/* 'c' is a register */
		const char* what = getobjname(p, pc, c, name); /* search for 'c' */
		if (what && *what == 'c')
		{
			/* found a constant name? */
			return; /* 'name' already filled */
		}
		/* else no reasonable name found */
	}
	*name = "?"; /* no reasonable name found */
}


static int filterpc(int pc, int jmptarget)
{
	if (pc < jmptarget) /* is code conditional (inside a jump)? */
		return -1; /* cannot know who sets that register */
	else return pc; /* current position sets that register */
}


/*
** try to find last instruction before 'lastpc' that modified register 'reg'
*/
static int findsetreg(Proto* p, int lastpc, int reg)
{
	int pc;
	int setreg = -1; /* keep last instruction that changed 'reg' */
	int jmptarget = 0; /* any code before this address is conditional */
	for (pc = 0; pc < lastpc; pc++)
	{
		Instruction i = p->code[pc];
		OpCode op = GET_OPCODE(i);
		int a = GETARG_A(i);
		switch (op)
		{
		case OP_LOADNIL:
			{
				int b = GETARG_B(i);
				if (a <= reg && reg <= a + b) /* set registers from 'a' to 'a+b' */
					setreg = filterpc(pc, jmptarget);
				break;
			}
		case OP_TFORCALL:
			{
				if (reg >= a + 2) /* affect all regs above its base */
					setreg = filterpc(pc, jmptarget);
				break;
			}
		case OP_CALL:
		case OP_TAILCALL:
			{
				if (reg >= a) /* affect all registers above base */
					setreg = filterpc(pc, jmptarget);
				break;
			}
		case OP_JMP:
			{
				int b = GETARG_sBx(i);
				int dest = pc + 1 + b;
				/* jump is forward and do not skip 'lastpc'? */
				if (pc < dest && dest <= lastpc)
				{
					if (dest > jmptarget)
						jmptarget = dest; /* update 'jmptarget' */
				}
				break;
			}
		default:
			if (testAMode(op) && reg == a) /* any instruction that set A */
				setreg = filterpc(pc, jmptarget);
			break;
		}
	}
	return setreg;
}


static const char* getobjname(Proto* p, int lastpc, int reg,
                              const char** name)
{
	int pc;
	*name = luaF_getlocalname(p, reg + 1, lastpc);
	if (*name) /* is a local? */
		return "local";
	/* else try symbolic execution */
	pc = findsetreg(p, lastpc, reg);
	if (pc != -1)
	{
		/* could find instruction? */
		Instruction i = p->code[pc];
		OpCode op = GET_OPCODE(i);
		switch (op)
		{
		case OP_MOVE:
			{
				int b = GETARG_B(i); /* move from 'b' to 'a' */
				if (b < GETARG_A(i))
					return getobjname(p, pc, b, name); /* get name for 'b' */
				break;
			}
		case OP_GETTABUP:
		case OP_GETTABLE:
			{
				int k = GETARG_C(i); /* key index */
				int t = GETARG_B(i); /* table index */
				const char* vn = (op == OP_GETTABLE) /* name of indexed variable */
					                 ? luaF_getlocalname(p, t + 1, pc)
					                 : upvalname(p, t);
				kname(p, pc, k, name);
				return (vn && strcmp(vn, LUA_ENV) == 0) ? "global" : "field";
			}
		case OP_GETUPVAL:
			{
				*name = upvalname(p, GETARG_B(i));
				return "upvalue";
			}
		case OP_LOADK:
		case OP_LOADKX:
			{
				int b = (op == OP_LOADK)
					        ? GETARG_Bx(i)
					        : GETARG_Ax(p->code[pc + 1]);
				if (ttisstring(&p->k[b]))
				{
					*name = svalue(&p->k[b]);
					return "constant";
				}
				break;
			}
		case OP_SELF:
			{
				int k = GETARG_C(i); /* key index */
				kname(p, pc, k, name);
				return "method";
			}
		default: break; /* go through to return NULL */
		}
	}
	return NULL; /* could not find reasonable name */
}


/*
** Try to find a name for a function based on the code that called it.
** (Only works when function was called by a Lua function.)
** Returns what the name is (e.g., "for iterator", "method",
** "metamethod") and sets '*name' to point to the name.
*/
static const char* funcnamefromcode(lua_State* L, CallInfo* ci,
                                    const char** name)
{
	TMS tm = (TMS)0; /* (initial value avoids warnings) */
	Proto* p = ci_func(ci)->p; /* calling function */
	int pc = currentpc(ci); /* calling instruction index */
	Instruction i = p->code[pc]; /* calling instruction */
	if (ci->callstatus & CIST_HOOKED)
	{
		/* was it called inside a hook? */
		*name = "?";
		return "hook";
	}
	switch (GET_OPCODE(i))
	{
	case OP_CALL:
	case OP_TAILCALL:
		return getobjname(p, pc, GETARG_A(i), name); /* get function name */
	case OP_TFORCALL:
		{
			/* for iterator */
			*name = "for iterator";
			return "for iterator";
		}
		/* other instructions can do calls through metamethods */
	case OP_SELF:
	case OP_GETTABUP:
	case OP_GETTABLE:
		tm = TM_INDEX;
		break;
	case OP_SETTABUP:
	case OP_SETTABLE:
		tm = TM_NEWINDEX;
		break;
	case OP_ADD:
	case OP_SUB:
	case OP_MUL:
	case OP_MOD:
	case OP_POW:
	case OP_DIV:
	case OP_IDIV:
	case OP_BAND:
	case OP_BOR:
	case OP_BXOR:
	case OP_SHL:
	case OP_SHR:
		{
			int offset = cast_int(GET_OPCODE(i)) - cast_int(OP_ADD); /* ORDER OP */
			tm = cast(TMS, offset + cast_int(TM_ADD)); /* ORDER TM */
			break;
		}
	case OP_UNM: tm = TM_UNM;
		break;
	case OP_BNOT: tm = TM_BNOT;
		break;
	case OP_LEN: tm = TM_LEN;
		break;
	case OP_CONCAT: tm = TM_CONCAT;
		break;
	case OP_EQ: tm = TM_EQ;
		break;
	case OP_LT: tm = TM_LT;
		break;
	case OP_LE: tm = TM_LE;
		break;
	default:
		return NULL; /* cannot find a reasonable name */
	}
	*name = getstr(G(L)->tmname[tm]);
	return "metamethod";
}

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


/*
** The subtraction of two potentially unrelated pointers is
** not ISO C, but it should not crash a program; the subsequent
** checks are ISO C and ensure a correct result.
*/
static int isinstack(CallInfo* ci, const TValue* o)
{
	ptrdiff_t i = o - ci->u.l.base;
	return (0 <= i && i < (ci->top - ci->u.l.base) && ci->u.l.base + i == o);
}


/*
** Checks whether value 'o' came from an upvalue. (That can only happen
** with instructions OP_GETTABUP/OP_SETTABUP, which operate directly on
** upvalues.)
*/
static const char* getupvalname(CallInfo* ci, const TValue* o,
                                const char** name)
{
	LClosure* c = ci_func(ci);
	int i;
	for (i = 0; i < c->nupvalues; i++)
	{
		if (c->upvals[i]->v == o)
		{
			*name = upvalname(c->p, i);
			return "upvalue";
		}
	}
	return NULL;
}


static const char* varinfo(lua_State* L, const TValue* o)
{
	const char* name = NULL; /* to avoid warnings */
	CallInfo* ci = L->ci;
	const char* kind = NULL;
	if (isLua(ci))
	{
		kind = getupvalname(ci, o, &name); /* check whether 'o' is an upvalue */
		if (!kind && isinstack(ci, o)) /* no? try a register */
			kind = getobjname(ci_func(ci)->p, currentpc(ci),
			                  cast_int(o - ci->u.l.base), &name);
	}
	return (kind) ? luaO_pushfstring(L, " (%s '%s')", kind, name) : "";
}


l_noret luaG_typeerror(lua_State* L, const TValue* o, const char* op)
{
	const char* t = luaT_objtypename(L, o);
	luaG_runerror(L, "attempt to %s a %s value%s", op, t, varinfo(L, o));
}


l_noret luaG_concaterror(lua_State* L, const TValue* p1, const TValue* p2)
{
	if (ttisstring(p1) || cvt2str(p1)) p1 = p2;
	luaG_typeerror(L, p1, "concatenate");
}


l_noret luaG_opinterror(lua_State* L, const TValue* p1,
                        const TValue* p2, const char* msg)
{
	lua_Number temp;
	if (!tonumber(p1, &temp)) /* first operand is wrong? */
		p2 = p1; /* now second is wrong */
	luaG_typeerror(L, p2, msg);
}


/*
** Error when both values are convertible to numbers, but not to integers
*/
l_noret luaG_tointerror(lua_State* L, const TValue* p1, const TValue* p2)
{
	lua_Integer temp;
	if (!tointeger(p1, &temp))
		p2 = p1;
	luaG_runerror(L, "number%s has no integer representation", varinfo(L, p2));
}


l_noret luaG_ordererror(lua_State* L, const TValue* p1, const TValue* p2)
{
	const char* t1 = luaT_objtypename(L, p1);
	const char* t2 = luaT_objtypename(L, p2);
	if (strcmp(t1, t2) == 0)
		luaG_runerror(L, "attempt to compare two %s values", t1);
	else
		luaG_runerror(L, "attempt to compare %s with %s", t1, t2);
}


/* add src:line information to 'msg' */
const char* luaG_addinfo(lua_State* L, const char* msg, TString* src,
                         int line)
{
	char buff[LUA_IDSIZE];
	if (src)
		luaO_chunkid(buff, getstr(src), LUA_IDSIZE);
	else
	{
		/* no source available; use "?" instead */
		buff[0] = '?';
		buff[1] = '\0';
	}
	return luaO_pushfstring(L, "%s:%d: %s", buff, line, msg);
}


l_noret luaG_errormsg(lua_State* L)
{
	if (L->errfunc != 0)
	{
		/* is there an error handling function? */
		StkId errfunc = restorestack(L, L->errfunc);
		setobjs2s(L, L->top, L->top - 1); /* move argument */
		setobjs2s(L, L->top - 1, errfunc); /* push function */
		L->top++; /* assume EXTRA_STACK */
		luaD_callnoyield(L, L->top - 2, 1); /* call it */
	}
	luaD_throw(L, LUA_ERRRUN);
}


l_noret luaG_runerror(lua_State* L, const char* fmt, ...)
{
	CallInfo* ci = L->ci;
	const char* msg;
	va_list argp;
	va_start(argp, fmt);
	msg = luaO_pushvfstring(L, fmt, argp); /* format message */
	va_end(argp);
	if (isLua(ci)) /* if Lua function, add source:line information */
		luaG_addinfo(L, msg, ci_func(ci)->p->source, currentline(ci));
	luaG_errormsg(L);
}


void luaG_traceexec(lua_State* L)
{
	CallInfo* ci = L->ci;
	lu_byte mask = L->hookmask;
	int counthook = (--L->hookcount == 0 && (mask & LUA_MASKCOUNT));
	if (counthook)
		resethookcount(L); /* reset count */
	else if (!(mask & LUA_MASKLINE))
		return; /* no line hook and count != 0; nothing to be done */
	if (ci->callstatus & CIST_HOOKYIELD)
	{
		/* called hook last time? */
		ci->callstatus &= ~CIST_HOOKYIELD; /* erase mark */
		return; /* do not call hook again (VM yielded, so it did not move) */
	}
	if (counthook)
		luaD_hook(L, LUA_HOOKCOUNT, -1); /* call count hook */
	if (mask & LUA_MASKLINE)
	{
		Proto* p = ci_func(ci)->p;
		int npc = pcRel(ci->u.l.savedpc, p);
		int newline = getfuncline(p, npc);
		if (npc == 0 || /* call linehook when enter a new function, */
			ci->u.l.savedpc <= L->oldpc || /* when jump back (loop), or when */
			newline != getfuncline(p, pcRel(L->oldpc, p))) /* enter a new line */
			luaD_hook(L, LUA_HOOKLINE, newline); /* call line hook */
	}
	L->oldpc = ci->u.l.savedpc;
	if (L->status == LUA_YIELD)
	{
		/* did hook yield? */
		if (counthook)
			L->hookcount = 1; /* undo decrement to zero */
		ci->u.l.savedpc--; /* undo increment (resume will increment it again) */
		ci->callstatus |= CIST_HOOKYIELD; /* mark that it yielded */
		ci->func = L->top - 1; /* protect stack below results */
		luaD_throw(L, LUA_YIELD);
	}
}