deps/lua/src/ldblib.c

/*
** $Id: ldblib.c,v 1.104.1.3 2008/01/21 13:11:21 roberto Exp $
** Interface from Lua to its debug API
** See Copyright Notice in lua.h
*/


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define ldblib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


static int db_getregistry (lua_State *L) {
  lua_pushvalue(L, LUA_REGISTRYINDEX);
  return 1;
}


static int db_getmetatable (lua_State *L) {
  luaL_checkany(L, 1);
  if (!lua_getmetatable(L, 1)) {
    lua_pushnil(L);  /* no metatable */
  }
  return 1;
}


static int db_setmetatable (lua_State *L) {
  int t = lua_type(L, 2);
  luaL_argcheck(L, t == LUA_TNIL || t == LUA_TTABLE, 2,
                    "nil or table expected");
  lua_settop(L, 2);
  lua_pushboolean(L, lua_setmetatable(L, 1));
  return 1;
}


static int db_getfenv (lua_State *L) {
  lua_getfenv(L, 1);
  return 1;
}


static int db_setfenv (lua_State *L) {
  luaL_checktype(L, 2, LUA_TTABLE);
  lua_settop(L, 2);
  if (lua_setfenv(L, 1) == 0)
    luaL_error(L, LUA_QL("setfenv")
                  " cannot change environment of given object");
  return 1;
}


static void settabss (lua_State *L, const char *i, const char *v) {
  lua_pushstring(L, v);
  lua_setfield(L, -2, i);
}


static void settabsi (lua_State *L, const char *i, int v) {
  lua_pushinteger(L, v);
  lua_setfield(L, -2, i);
}


static lua_State *getthread (lua_State *L, int *arg) {
  if (lua_isthread(L, 1)) {
    *arg = 1;
    return lua_tothread(L, 1);
  }
  else {
    *arg = 0;
    return L;
  }
}


static void treatstackoption (lua_State *L, lua_State *L1, const char *fname) {
  if (L == L1) {
    lua_pushvalue(L, -2);
    lua_remove(L, -3);
  }
  else
    lua_xmove(L1, L, 1);
  lua_setfield(L, -2, fname);
}


static int db_getinfo (lua_State *L) {
  lua_Debug ar;
  int arg;
  lua_State *L1 = getthread(L, &arg);
  const char *options = luaL_optstring(L, arg+2, "flnSu");
  if (lua_isnumber(L, arg+1)) {
    if (!lua_getstack(L1, (int)lua_tointeger(L, arg+1), &ar)) {
      lua_pushnil(L);  /* level out of range */
      return 1;
    }
  }
  else if (lua_isfunction(L, arg+1)) {
    lua_pushfstring(L, ">%s", options);
    options = lua_tostring(L, -1);
    lua_pushvalue(L, arg+1);
    lua_xmove(L, L1, 1);
  }
  else
    return luaL_argerror(L, arg+1, "function or level expected");
  if (!lua_getinfo(L1, options, &ar))
    return luaL_argerror(L, arg+2, "invalid option");
  lua_createtable(L, 0, 2);
  if (strchr(options, 'S')) {
    settabss(L, "source", ar.source);
    settabss(L, "short_src", ar.short_src);
    settabsi(L, "linedefined", ar.linedefined);
    settabsi(L, "lastlinedefined", ar.lastlinedefined);
    settabss(L, "what", ar.what);
  }
  if (strchr(options, 'l'))
    settabsi(L, "currentline", ar.currentline);
  if (strchr(options, 'u'))
    settabsi(L, "nups", ar.nups);
  if (strchr(options, 'n')) {
    settabss(L, "name", ar.name);
    settabss(L, "namewhat", ar.namewhat);
  }
  if (strchr(options, 'L'))
    treatstackoption(L, L1, "activelines");
  if (strchr(options, 'f'))
    treatstackoption(L, L1, "func");
  return 1;  /* return table */
}


static int db_getlocal (lua_State *L) {
  int arg;
  lua_State *L1 = getthread(L, &arg);
  lua_Debug ar;
  const char *name;
  if (!lua_getstack(L1, luaL_checkint(L, arg+1), &ar))  /* out of range? */
    return luaL_argerror(L, arg+1, "level out of range");
  name = lua_getlocal(L1, &ar, luaL_checkint(L, arg+2));
  if (name) {
    lua_xmove(L1, L, 1);
    lua_pushstring(L, name);
    lua_pushvalue(L, -2);
    return 2;
  }
  else {
    lua_pushnil(L);
    return 1;
  }
}


static int db_setlocal (lua_State *L) {
  int arg;
  lua_State *L1 = getthread(L, &arg);
  lua_Debug ar;
  if (!lua_getstack(L1, luaL_checkint(L, arg+1), &ar))  /* out of range? */
    return luaL_argerror(L, arg+1, "level out of range");
  luaL_checkany(L, arg+3);
  lua_settop(L, arg+3);
  lua_xmove(L, L1, 1);
  lua_pushstring(L, lua_setlocal(L1, &ar, luaL_checkint(L, arg+2)));
  return 1;
}


static int auxupvalue (lua_State *L, int get) {
  const char *name;
  int n = luaL_checkint(L, 2);
  luaL_checktype(L, 1, LUA_TFUNCTION);
  if (lua_iscfunction(L, 1)) return 0;  /* cannot touch C upvalues from Lua */
  name = get ? lua_getupvalue(L, 1, n) : lua_setupvalue(L, 1, n);
  if (name == NULL) return 0;
  lua_pushstring(L, name);
  lua_insert(L, -(get+1));
  return get + 1;
}


static int db_getupvalue (lua_State *L) {
  return auxupvalue(L, 1);
}


static int db_setupvalue (lua_State *L) {
  luaL_checkany(L, 3);
  return auxupvalue(L, 0);
}


static const char KEY_HOOK = 'h';


static void hookf (lua_State *L, lua_Debug *ar) {
  static const char *const hooknames[] =
    {"call", "return", "line", "count", "tail return"};
  lua_pushlightuserdata(L, (void *)&KEY_HOOK);
  lua_rawget(L, LUA_REGISTRYINDEX);
  lua_pushlightuserdata(L, L);
  lua_rawget(L, -2);
  if (lua_isfunction(L, -1)) {
    lua_pushstring(L, hooknames[(int)ar->event]);
    if (ar->currentline >= 0)
      lua_pushinteger(L, ar->currentline);
    else lua_pushnil(L);
    lua_assert(lua_getinfo(L, "lS", ar));
    lua_call(L, 2, 0);
  }
}


static int makemask (const char *smask, int count) {
  int mask = 0;
  if (strchr(smask, 'c')) mask |= LUA_MASKCALL;
  if (strchr(smask, 'r')) mask |= LUA_MASKRET;
  if (strchr(smask, 'l')) mask |= LUA_MASKLINE;
  if (count > 0) mask |= LUA_MASKCOUNT;
  return mask;
}


static char *unmakemask (int mask, char *smask) {
  int i = 0;
  if (mask & LUA_MASKCALL) smask[i++] = 'c';
  if (mask & LUA_MASKRET) smask[i++] = 'r';
  if (mask & LUA_MASKLINE) smask[i++] = 'l';
  smask[i] = '\0';
  return smask;
}


static void gethooktable (lua_State *L) {
  lua_pushlightuserdata(L, (void *)&KEY_HOOK);
  lua_rawget(L, LUA_REGISTRYINDEX);
  if (!lua_istable(L, -1)) {
    lua_pop(L, 1);
    lua_createtable(L, 0, 1);
    lua_pushlightuserdata(L, (void *)&KEY_HOOK);
    lua_pushvalue(L, -2);
    lua_rawset(L, LUA_REGISTRYINDEX);
  }
}


static int db_sethook (lua_State *L) {
  int arg, mask, count;
  lua_Hook func;
  lua_State *L1 = getthread(L, &arg);
  if (lua_isnoneornil(L, arg+1)) {
    lua_settop(L, arg+1);
    func = NULL; mask = 0; count = 0;  /* turn off hooks */
  }
  else {
    const char *smask = luaL_checkstring(L, arg+2);
    luaL_checktype(L, arg+1, LUA_TFUNCTION);
    count = luaL_optint(L, arg+3, 0);
    func = hookf; mask = makemask(smask, count);
  }
  gethooktable(L);
  lua_pushlightuserdata(L, L1);
  lua_pushvalue(L, arg+1);
  lua_rawset(L, -3);  /* set new hook */
  lua_pop(L, 1);  /* remove hook table */
  lua_sethook(L1, func, mask, count);  /* set hooks */
  return 0;
}


static int db_gethook (lua_State *L) {
  int arg;
  lua_State *L1 = getthread(L, &arg);
  char buff[5];
  int mask = lua_gethookmask(L1);
  lua_Hook hook = lua_gethook(L1);
  if (hook != NULL && hook != hookf)  /* external hook? */
    lua_pushliteral(L, "external hook");
  else {
    gethooktable(L);
    lua_pushlightuserdata(L, L1);
    lua_rawget(L, -2);   /* get hook */
    lua_remove(L, -2);  /* remove hook table */
  }
  lua_pushstring(L, unmakemask(mask, buff));
  lua_pushinteger(L, lua_gethookcount(L1));
  return 3;
}


static int db_debug (lua_State *L) {
  for (;;) {
    char buffer[250];
    fputs("lua_debug> ", stderr);
    if (fgets(buffer, sizeof(buffer), stdin) == 0 ||
        strcmp(buffer, "cont\n") == 0)
      return 0;
    if (luaL_loadbuffer(L, buffer, strlen(buffer), "=(debug command)") ||
        lua_pcall(L, 0, 0, 0)) {
      fputs(lua_tostring(L, -1), stderr);
      fputs("\n", stderr);
    }
    lua_settop(L, 0);  /* remove eventual returns */
  }
}


#define LEVELS1	12	/* size of the first part of the stack */
#define LEVELS2	10	/* size of the second part of the stack */

static int db_errorfb (lua_State *L) {
  int level;
  int firstpart = 1;  /* still before eventual `...' */
  int arg;
  lua_State *L1 = getthread(L, &arg);
  lua_Debug ar;
  if (lua_isnumber(L, arg+2)) {
    level = (int)lua_tointeger(L, arg+2);
    lua_pop(L, 1);
  }
  else
    level = (L == L1) ? 1 : 0;  /* level 0 may be this own function */
  if (lua_gettop(L) == arg)
    lua_pushliteral(L, "");
  else if (!lua_isstring(L, arg+1)) return 1;  /* message is not a string */
  else lua_pushliteral(L, "\n");
  lua_pushliteral(L, "stack traceback:");
  while (lua_getstack(L1, level++, &ar)) {
    if (level > LEVELS1 && firstpart) {
      /* no more than `LEVELS2' more levels? */
      if (!lua_getstack(L1, level+LEVELS2, &ar))
        level--;  /* keep going */
      else {
        lua_pushliteral(L, "\n\t...");  /* too many levels */
        while (lua_getstack(L1, level+LEVELS2, &ar))  /* find last levels */
          level++;
      }
      firstpart = 0;
      continue;
    }
    lua_pushliteral(L, "\n\t");
    lua_getinfo(L1, "Snl", &ar);
    lua_pushfstring(L, "%s:", ar.short_src);
    if (ar.currentline > 0)
      lua_pushfstring(L, "%d:", ar.currentline);
    if (*ar.namewhat != '\0')  /* is there a name? */
        lua_pushfstring(L, " in function " LUA_QS, ar.name);
    else {
      if (*ar.what == 'm')  /* main? */
        lua_pushfstring(L, " in main chunk");
      else if (*ar.what == 'C' || *ar.what == 't')
        lua_pushliteral(L, " ?");  /* C function or tail call */
      else
        lua_pushfstring(L, " in function <%s:%d>",
                           ar.short_src, ar.linedefined);
    }
    lua_concat(L, lua_gettop(L) - arg);
  }
  lua_concat(L, lua_gettop(L) - arg);
  return 1;
}


static const luaL_Reg dblib[] = {
  {"debug", db_debug},
  {"getfenv", db_getfenv},
  {"gethook", db_gethook},
  {"getinfo", db_getinfo},
  {"getlocal", db_getlocal},
  {"getregistry", db_getregistry},
  {"getmetatable", db_getmetatable},
  {"getupvalue", db_getupvalue},
  {"setfenv", db_setfenv},
  {"sethook", db_sethook},
  {"setlocal", db_setlocal},
  {"setmetatable", db_setmetatable},
  {"setupvalue", db_setupvalue},
  {"traceback", db_errorfb},
  {NULL, NULL}
};


LUALIB_API int luaopen_debug (lua_State *L) {
  luaL_register(L, LUA_DBLIBNAME, dblib);
  return 1;
}
Commit	Line	Data
	1	/*
	2	** $Id: ldblib.c,v 1.104.1.3 2008/01/21 13:11:21 roberto Exp $
	3	** Interface from Lua to its debug API
	4	** See Copyright Notice in lua.h
	5	*/
	6
	7
	8	#include <stdio.h>
	9	#include <stdlib.h>
	10	#include <string.h>
	11
	12	#define ldblib_c
	13	#define LUA_LIB
	14
	15	#include "lua.h"
	16
	17	#include "lauxlib.h"
	18	#include "lualib.h"
	19
	20
	21
	22	static int db_getregistry (lua_State *L) {
	23	lua_pushvalue(L, LUA_REGISTRYINDEX);
	24	return 1;
	25	}
	26
	27
	28	static int db_getmetatable (lua_State *L) {
	29	luaL_checkany(L, 1);
	30	if (!lua_getmetatable(L, 1)) {
	31	lua_pushnil(L); /* no metatable */
	32	}
	33	return 1;
	34	}
	35
	36
	37	static int db_setmetatable (lua_State *L) {
	38	int t = lua_type(L, 2);
	39	luaL_argcheck(L, t == LUA_TNIL \|\| t == LUA_TTABLE, 2,
	40	"nil or table expected");
	41	lua_settop(L, 2);
	42	lua_pushboolean(L, lua_setmetatable(L, 1));
	43	return 1;
	44	}
	45
	46
	47	static int db_getfenv (lua_State *L) {
	48	lua_getfenv(L, 1);
	49	return 1;
	50	}
	51
	52
	53	static int db_setfenv (lua_State *L) {
	54	luaL_checktype(L, 2, LUA_TTABLE);
	55	lua_settop(L, 2);
	56	if (lua_setfenv(L, 1) == 0)
	57	luaL_error(L, LUA_QL("setfenv")
	58	" cannot change environment of given object");
	59	return 1;
	60	}
	61
	62
	63	static void settabss (lua_State L, const char i, const char *v) {
	64	lua_pushstring(L, v);
	65	lua_setfield(L, -2, i);
	66	}
	67
	68
	69	static void settabsi (lua_State L, const char i, int v) {
	70	lua_pushinteger(L, v);
	71	lua_setfield(L, -2, i);
	72	}
	73
	74
	75	static lua_State getthread (lua_State L, int *arg) {
	76	if (lua_isthread(L, 1)) {
	77	*arg = 1;
	78	return lua_tothread(L, 1);
	79	}
	80	else {
	81	*arg = 0;
	82	return L;
	83	}
	84	}
	85
	86
	87	static void treatstackoption (lua_State L, lua_State L1, const char *fname) {
	88	if (L == L1) {
	89	lua_pushvalue(L, -2);
	90	lua_remove(L, -3);
	91	}
	92	else
	93	lua_xmove(L1, L, 1);
	94	lua_setfield(L, -2, fname);
	95	}
	96
	97
	98	static int db_getinfo (lua_State *L) {
	99	lua_Debug ar;
	100	int arg;
	101	lua_State *L1 = getthread(L, &arg);
	102	const char *options = luaL_optstring(L, arg+2, "flnSu");
	103	if (lua_isnumber(L, arg+1)) {
	104	if (!lua_getstack(L1, (int)lua_tointeger(L, arg+1), &ar)) {
	105	lua_pushnil(L); /* level out of range */
	106	return 1;
	107	}
	108	}
	109	else if (lua_isfunction(L, arg+1)) {
	110	lua_pushfstring(L, ">%s", options);
	111	options = lua_tostring(L, -1);
	112	lua_pushvalue(L, arg+1);
	113	lua_xmove(L, L1, 1);
	114	}
	115	else
	116	return luaL_argerror(L, arg+1, "function or level expected");
	117	if (!lua_getinfo(L1, options, &ar))
	118	return luaL_argerror(L, arg+2, "invalid option");
	119	lua_createtable(L, 0, 2);
	120	if (strchr(options, 'S')) {
	121	settabss(L, "source", ar.source);
	122	settabss(L, "short_src", ar.short_src);
	123	settabsi(L, "linedefined", ar.linedefined);
	124	settabsi(L, "lastlinedefined", ar.lastlinedefined);
	125	settabss(L, "what", ar.what);
	126	}
	127	if (strchr(options, 'l'))
	128	settabsi(L, "currentline", ar.currentline);
	129	if (strchr(options, 'u'))
	130	settabsi(L, "nups", ar.nups);
	131	if (strchr(options, 'n')) {
	132	settabss(L, "name", ar.name);
	133	settabss(L, "namewhat", ar.namewhat);
	134	}
	135	if (strchr(options, 'L'))
	136	treatstackoption(L, L1, "activelines");
	137	if (strchr(options, 'f'))
	138	treatstackoption(L, L1, "func");
	139	return 1; /* return table */
	140	}
	141
	142
	143	static int db_getlocal (lua_State *L) {
	144	int arg;
	145	lua_State *L1 = getthread(L, &arg);
	146	lua_Debug ar;
	147	const char *name;
	148	if (!lua_getstack(L1, luaL_checkint(L, arg+1), &ar)) /* out of range? */
	149	return luaL_argerror(L, arg+1, "level out of range");
	150	name = lua_getlocal(L1, &ar, luaL_checkint(L, arg+2));
	151	if (name) {
	152	lua_xmove(L1, L, 1);
	153	lua_pushstring(L, name);
	154	lua_pushvalue(L, -2);
	155	return 2;
	156	}
	157	else {
	158	lua_pushnil(L);
	159	return 1;
	160	}
	161	}
	162
	163
	164	static int db_setlocal (lua_State *L) {
	165	int arg;
	166	lua_State *L1 = getthread(L, &arg);
	167	lua_Debug ar;
	168	if (!lua_getstack(L1, luaL_checkint(L, arg+1), &ar)) /* out of range? */
	169	return luaL_argerror(L, arg+1, "level out of range");
	170	luaL_checkany(L, arg+3);
	171	lua_settop(L, arg+3);
	172	lua_xmove(L, L1, 1);
	173	lua_pushstring(L, lua_setlocal(L1, &ar, luaL_checkint(L, arg+2)));
	174	return 1;
	175	}
	176
	177
	178	static int auxupvalue (lua_State *L, int get) {
	179	const char *name;
	180	int n = luaL_checkint(L, 2);
	181	luaL_checktype(L, 1, LUA_TFUNCTION);
	182	if (lua_iscfunction(L, 1)) return 0; /* cannot touch C upvalues from Lua */
	183	name = get ? lua_getupvalue(L, 1, n) : lua_setupvalue(L, 1, n);
	184	if (name == NULL) return 0;
	185	lua_pushstring(L, name);
	186	lua_insert(L, -(get+1));
	187	return get + 1;
	188	}
	189
	190
	191	static int db_getupvalue (lua_State *L) {
	192	return auxupvalue(L, 1);
	193	}
	194
	195
	196	static int db_setupvalue (lua_State *L) {
	197	luaL_checkany(L, 3);
	198	return auxupvalue(L, 0);
	199	}
	200
	201
	202
	203	static const char KEY_HOOK = 'h';
	204
	205
	206	static void hookf (lua_State L, lua_Debug ar) {
	207	static const char *const hooknames[] =
	208	{"call", "return", "line", "count", "tail return"};
	209	lua_pushlightuserdata(L, (void *)&KEY_HOOK);
	210	lua_rawget(L, LUA_REGISTRYINDEX);
	211	lua_pushlightuserdata(L, L);
	212	lua_rawget(L, -2);
	213	if (lua_isfunction(L, -1)) {
	214	lua_pushstring(L, hooknames[(int)ar->event]);
	215	if (ar->currentline >= 0)
	216	lua_pushinteger(L, ar->currentline);
	217	else lua_pushnil(L);
	218	lua_assert(lua_getinfo(L, "lS", ar));
	219	lua_call(L, 2, 0);
	220	}
	221	}
	222
	223
	224	static int makemask (const char *smask, int count) {
	225	int mask = 0;
	226	if (strchr(smask, 'c')) mask \|= LUA_MASKCALL;
	227	if (strchr(smask, 'r')) mask \|= LUA_MASKRET;
	228	if (strchr(smask, 'l')) mask \|= LUA_MASKLINE;
	229	if (count > 0) mask \|= LUA_MASKCOUNT;
	230	return mask;
	231	}
	232
	233
	234	static char unmakemask (int mask, char smask) {
	235	int i = 0;
	236	if (mask & LUA_MASKCALL) smask[i++] = 'c';
	237	if (mask & LUA_MASKRET) smask[i++] = 'r';
	238	if (mask & LUA_MASKLINE) smask[i++] = 'l';
	239	smask[i] = '\0';
	240	return smask;
	241	}
	242
	243
	244	static void gethooktable (lua_State *L) {
	245	lua_pushlightuserdata(L, (void *)&KEY_HOOK);
	246	lua_rawget(L, LUA_REGISTRYINDEX);
	247	if (!lua_istable(L, -1)) {
	248	lua_pop(L, 1);
	249	lua_createtable(L, 0, 1);
	250	lua_pushlightuserdata(L, (void *)&KEY_HOOK);
	251	lua_pushvalue(L, -2);
	252	lua_rawset(L, LUA_REGISTRYINDEX);
	253	}
	254	}
	255
	256
	257	static int db_sethook (lua_State *L) {
	258	int arg, mask, count;
	259	lua_Hook func;
	260	lua_State *L1 = getthread(L, &arg);
	261	if (lua_isnoneornil(L, arg+1)) {
	262	lua_settop(L, arg+1);
	263	func = NULL; mask = 0; count = 0; /* turn off hooks */
	264	}
	265	else {
	266	const char *smask = luaL_checkstring(L, arg+2);
	267	luaL_checktype(L, arg+1, LUA_TFUNCTION);
	268	count = luaL_optint(L, arg+3, 0);
	269	func = hookf; mask = makemask(smask, count);
	270	}
	271	gethooktable(L);
	272	lua_pushlightuserdata(L, L1);
	273	lua_pushvalue(L, arg+1);
	274	lua_rawset(L, -3); /* set new hook */
	275	lua_pop(L, 1); /* remove hook table */
	276	lua_sethook(L1, func, mask, count); /* set hooks */
	277	return 0;
	278	}
	279
	280
	281	static int db_gethook (lua_State *L) {
	282	int arg;
	283	lua_State *L1 = getthread(L, &arg);
	284	char buff[5];
	285	int mask = lua_gethookmask(L1);
	286	lua_Hook hook = lua_gethook(L1);
	287	if (hook != NULL && hook != hookf) /* external hook? */
	288	lua_pushliteral(L, "external hook");
	289	else {
	290	gethooktable(L);
	291	lua_pushlightuserdata(L, L1);
	292	lua_rawget(L, -2); /* get hook */
	293	lua_remove(L, -2); /* remove hook table */
	294	}
	295	lua_pushstring(L, unmakemask(mask, buff));
	296	lua_pushinteger(L, lua_gethookcount(L1));
	297	return 3;
	298	}
	299
	300
	301	static int db_debug (lua_State *L) {
	302	for (;;) {
	303	char buffer[250];
	304	fputs("lua_debug> ", stderr);
	305	if (fgets(buffer, sizeof(buffer), stdin) == 0 \|\|
	306	strcmp(buffer, "cont\n") == 0)
	307	return 0;
	308	if (luaL_loadbuffer(L, buffer, strlen(buffer), "=(debug command)") \|\|
	309	lua_pcall(L, 0, 0, 0)) {
	310	fputs(lua_tostring(L, -1), stderr);
	311	fputs("\n", stderr);
	312	}
	313	lua_settop(L, 0); /* remove eventual returns */
	314	}
	315	}
	316
	317
	318	#define LEVELS1 12 /* size of the first part of the stack */
	319	#define LEVELS2 10 /* size of the second part of the stack */
	320
	321	static int db_errorfb (lua_State *L) {
	322	int level;
	323	int firstpart = 1; /* still before eventual `...' */
	324	int arg;
	325	lua_State *L1 = getthread(L, &arg);
	326	lua_Debug ar;
	327	if (lua_isnumber(L, arg+2)) {
	328	level = (int)lua_tointeger(L, arg+2);
	329	lua_pop(L, 1);
	330	}
	331	else
	332	level = (L == L1) ? 1 : 0; /* level 0 may be this own function */
	333	if (lua_gettop(L) == arg)
	334	lua_pushliteral(L, "");
	335	else if (!lua_isstring(L, arg+1)) return 1; /* message is not a string */
	336	else lua_pushliteral(L, "\n");
	337	lua_pushliteral(L, "stack traceback:");
	338	while (lua_getstack(L1, level++, &ar)) {
	339	if (level > LEVELS1 && firstpart) {
	340	/* no more than `LEVELS2' more levels? */
	341	if (!lua_getstack(L1, level+LEVELS2, &ar))
	342	level--; /* keep going */
	343	else {
	344	lua_pushliteral(L, "\n\t..."); /* too many levels */
	345	while (lua_getstack(L1, level+LEVELS2, &ar)) /* find last levels */
	346	level++;
	347	}
	348	firstpart = 0;
	349	continue;
	350	}
	351	lua_pushliteral(L, "\n\t");
	352	lua_getinfo(L1, "Snl", &ar);
	353	lua_pushfstring(L, "%s:", ar.short_src);
	354	if (ar.currentline > 0)
	355	lua_pushfstring(L, "%d:", ar.currentline);
	356	if (ar.namewhat != '\0') / is there a name? */
	357	lua_pushfstring(L, " in function " LUA_QS, ar.name);
	358	else {
	359	if (ar.what == 'm') / main? */
	360	lua_pushfstring(L, " in main chunk");
	361	else if (ar.what == 'C' \|\| ar.what == 't')
	362	lua_pushliteral(L, " ?"); /* C function or tail call */
	363	else
	364	lua_pushfstring(L, " in function <%s:%d>",
	365	ar.short_src, ar.linedefined);
	366	}
	367	lua_concat(L, lua_gettop(L) - arg);
	368	}
	369	lua_concat(L, lua_gettop(L) - arg);
	370	return 1;
	371	}
	372
	373
	374	static const luaL_Reg dblib[] = {
	375	{"debug", db_debug},
	376	{"getfenv", db_getfenv},
	377	{"gethook", db_gethook},
	378	{"getinfo", db_getinfo},
	379	{"getlocal", db_getlocal},
	380	{"getregistry", db_getregistry},
	381	{"getmetatable", db_getmetatable},
	382	{"getupvalue", db_getupvalue},
	383	{"setfenv", db_setfenv},
	384	{"sethook", db_sethook},
	385	{"setlocal", db_setlocal},
	386	{"setmetatable", db_setmetatable},
	387	{"setupvalue", db_setupvalue},
	388	{"traceback", db_errorfb},
	389	{NULL, NULL}
	390	};
	391
	392
	393	LUALIB_API int luaopen_debug (lua_State *L) {
	394	luaL_register(L, LUA_DBLIBNAME, dblib);
	395	return 1;
	396	}
	397