/*
** $Id: ldebug.c,v 2.90.1.3 2013/05/16 16:04:15 roberto Exp $
** Debug Interface
** See Copyright Notice in lua.h
*/

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

#define ldebug_c
#define LUA_CORE

#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)

static const char *getfuncname(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));
}

/*
** this function can be called asynchronous (e.g. during a signal)
*/
LUA_API int 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);
	return 1;
}

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 >= 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);
	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 = 0; /* to avoid warnings */
		name = findlocal(L, ar->i_ci, n, &pos);
		if (name)
		{
			setobj2s(L, L->top, pos);
			api_incr_top(L);
		}
	}
	lua_unlock(L);
	return name;
}

LUA_API const char *lua_setlocal(lua_State *L, const lua_Debug *ar, int n)
{
	StkId pos = 0; /* to avoid warnings */
	const char *name = findlocal(L, ar->i_ci, n, &pos);
	lua_lock(L);
	if (name)
		setobjs2s(L, pos, L->top - 1);
	L->top--; /* pop value */
	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 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':
			{
				/* calling function is a known Lua function? */
				if (ci && !(ci->callstatus & CIST_TAIL) && isLua(ci->previous))
					ar->namewhat = getfuncname(L, ci->previous, &ar->name);
				else
					ar->namewhat = NULL;
				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);
	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);
	}
	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;
			}
			case OP_TEST:
			{
				if (reg == a) /* jumped code can change 'a' */
					setreg = filterpc(pc, 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 */
}

static const char *getfuncname(lua_State *L, CallInfo *ci, const char **name)
{
	TMS tm;
	Proto *p = ci_func(ci)->p;   /* calling function */
	int pc = currentpc(ci);      /* calling instruction index */
	Instruction i = p->code[pc]; /* calling instruction */
	switch (GET_OPCODE(i))
	{
		case OP_CALL:
		case OP_TAILCALL: /* get function name */
			return getobjname(p, pc, GETARG_A(i), name);
		case OP_TFORCALL:
		{ /* for iterator */
			*name = "for iterator";
			return "for iterator";
		}
		/* all other instructions can call only 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_EQ:
			tm = TM_EQ;
			break;
		case OP_ADD:
			tm = TM_ADD;
			break;
		case OP_SUB:
			tm = TM_SUB;
			break;
		case OP_MUL:
			tm = TM_MUL;
			break;
		case OP_DIV:
			tm = TM_DIV;
			break;
		case OP_MOD:
			tm = TM_MOD;
			break;
		case OP_POW:
			tm = TM_POW;
			break;
		case OP_UNM:
			tm = TM_UNM;
			break;
		case OP_LEN:
			tm = TM_LEN;
			break;
		case OP_LT:
			tm = TM_LT;
			break;
		case OP_LE:
			tm = TM_LE;
			break;
		case OP_CONCAT:
			tm = TM_CONCAT;
			break;
		default:
			return NULL; /* else no useful name can be found */
	}
	*name = getstr(G(L)->tmname[tm]);
	return "metamethod";
}

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

/*
** only ANSI way to check whether a pointer points to an array
** (used only for error messages, so efficiency is not a big concern)
*/
static int isinstack(CallInfo *ci, const TValue *o)
{
	StkId p;
	for (p = ci->u.l.base; p < ci->top; p++)
		if (o == p) return 1;
	return 0;
}

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;
}

l_noret luaG_typeerror(lua_State *L, const TValue *o, const char *op)
{
	CallInfo *ci = L->ci;
	const char *name = NULL;
	const char *t = objtypename(o);
	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);
	}
	if (kind)
		luaG_runerror(L, "attempt to %s %s " LUA_QS " (a %s value)",
					  op, kind, name, t);
	else
		luaG_runerror(L, "attempt to %s a %s value", op, t);
}

l_noret luaG_concaterror(lua_State *L, StkId p1, StkId p2)
{
	if (ttisstring(p1) || ttisnumber(p1)) p1 = p2;
	lua_assert(!ttisstring(p1) && !ttisnumber(p1));
	luaG_typeerror(L, p1, "concatenate");
}

l_noret luaG_aritherror(lua_State *L, const TValue *p1, const TValue *p2)
{
	TValue temp;
	if (luaV_tonumber(p1, &temp) == NULL)
		p2 = p1; /* first operand is wrong */
	luaG_typeerror(L, p2, "perform arithmetic on");
}

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

static void addinfo(lua_State *L, const char *msg)
{
	CallInfo *ci = L->ci;
	if (isLua(ci))
	{                          /* is Lua code? */
		char buff[LUA_IDSIZE]; /* add file:line information */
		int line = currentline(ci);
		TString *src = ci_func(ci)->p->source;
		if (src)
			luaO_chunkid(buff, getstr(src), LUA_IDSIZE);
		else
		{ /* no source available; use "?" instead */
			buff[0] = '?';
			buff[1] = '\0';
		}
		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);
		if (!ttisfunction(errfunc)) luaD_throw(L, LUA_ERRERR);
		setobjs2s(L, L->top, L->top - 1);  /* move argument */
		setobjs2s(L, L->top - 1, errfunc); /* push function */
		L->top++;
		luaD_call(L, L->top - 2, 1, 0); /* call it */
	}
	luaD_throw(L, LUA_ERRRUN);
}

l_noret luaG_runerror(lua_State *L, const char *fmt, ...)
{
	va_list argp;
	va_start(argp, fmt);
	addinfo(L, luaO_pushvfstring(L, fmt, argp));
	va_end(argp);
	luaG_errormsg(L);
}
