Re: dofile, loadfile, loadstring in a coroutine

[lists@...]

First of all, thanks for the help (and the explanation of the
lua_yield/lua_pcall constraint... I think I might get it now)
On Apr 21, 2007, at 2:35 PM, Rici Lake wrote:

Perhaps you should try:

print ("f()", f, xpcall(f, debug.traceback))

f = loadstring("print('hello')")
print ("f()", f, xpcall(f, debug.traceback))

--> 	f()	function: 0x1094250	true

i.e. no error, but no print('hello') either.

The only error I can think of is that 'print' isn't in the function
environment of the compiled chunk.

Shouldn't the xpcall return false and an error in this case?

I don't think you can resume the master state, although I could be wrong.

It works:

extern "C" {
	#include "lua.h"
	#include "lualib.h"
	#include "lauxlib.h"
}

int main (int argc, char ** argv)
{
	char * filename = "/test1.lua";
	int result;

	lua_State * L = luaL_newstate(); //lua_newstate(Lua :: alloc, 0);
	if (L) {
		luaL_openlibs(L);

		// luaL_dofile(L, "/preload1.lua"); // *1*

		if (luaL_loadfile (L, filename))
		{
			printf("luaL_loadfile error: %s", lua_tostring(L, -1));
			printf("luaL_loadfile failed");
			lua_pop(L, 1);
		}
		else
		{
			result = lua_resume(L, lua_gettop(L) - 1);
			printf("lua_resume result %i\n", result);
		}

	} else {
		printf("luaL_newstate failed\n");
	}
	return 0;
}

And if test1.lua contains this:

print("hello from test1.lua")
f = loadstring("print('hello from chunk')")
print ("f()", f, xpcall(f, debug.traceback)))

Then I correctly get:

hello from test1.lua
hello
f()	function: 0x307730	true
lua_resume result 0

I isolated the offending element - it is a token filter applied to the
state before loading the file.  If I remove the filter (*1* in the code
sample above), the function works as expected.

It looks like the line

loadstring("print('hello from chunk')")

is being trashed by the token FILTER, returning only <eof>.  Is this
because I'm calling it by resuming a thread?

I'm using Lua 5.1.2, with the token filter patch applied and proxy.c
included.

Here is preload1.lua, based upon the example in the tokenf package:

print("hello from preload1.lua")

-- debug filter
local function IN(get,put)
	put("IN init")
	while true do
		local line,token,value=get()
		print(line,token,value)
		put(line,token,value)
	end
end

local function OUT(get,put)
	put("OUT init")
	while true do
		local line,token,value=get()
		print("",line,token,value)
		put(line,token,value)
	end
end

local function pipe(f,get,put)
	put = put or coroutine.yield
	local F=coroutine.wrap(f)
	F(get,put)
	return F
end

function FILTER(get,source) FILTER=pipe(OUT,pipe(IN,get)) end

And here is the output if line *1* is uncommented:

hello from preload1.lua
1	<name>	print
	1	<name>	print
1	(	nil
	1	(	nil
1	<string>	hello from test1.lua
	1	<string>	hello from test1.lua
1	)	nil
	1	)	nil
3	<name>	f
	3	<name>	f
3	=	nil
	3	=	nil
3	<name>	loadstring
	3	<name>	loadstring
3	(	nil
	3	(	nil
3	<string>	print('hello from chunk')
	3	<string>	print('hello from chunk')
3	)	nil
	3	)	nil
4	<name>	print
	4	<name>	print
4	(	nil
	4	(	nil
4	<string>	f()
	4	<string>	f()
4	,	nil
	4	,	nil
4	<name>	f
	4	<name>	f
4	,	nil
	4	,	nil
4	<name>	xpcall
	4	<name>	xpcall
4	(	nil
	4	(	nil
4	<name>	f
	4	<name>	f
4	,	nil
	4	,	nil
4	<name>	debug
	4	<name>	debug
4	.	nil
	4	.	nil
4	<name>	traceback
	4	<name>	traceback
4	)	nil
	4	)	nil
4	)	nil
	4	)	nil
5	<eof>	nil
	5	<eof>	nil
hello from test1.lua
0	<eof>	nil
	0	<eof>	nil
0	<eof>	nil
	0	<eof>	nil
f()	function: 0x309410	true
lua_resume result 0

FWIW, I've included the patched llex.c at the end, in case there's
something there that might be the culprit.

llex.c:

/*
** $Id: llex.c,v 2.20 2006/03/09 18:14:31 roberto Exp $
** Lexical Analyzer
** See Copyright Notice in lua.h
*/


#include <ctype.h>
#include <locale.h>
#include <string.h>

#define llex_c
#define LUA_CORE

#include "lua.h"

#include "ldo.h"
#include "llex.h"
#include "lobject.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "lzio.h"



#define next(ls) (ls->current = zgetc(ls->z))




#define currIsNewline(ls)	(ls->current == '\n' || ls->current == '\r')


/* ORDER RESERVED */
const char *const luaX_tokens [] = {
    "and", "break", "do", "else", "elseif",
    "end", "false", "for", "function", "if",
    "in", "local", "nil", "not", "or", "repeat",
    "return", "then", "true", "until", "while",
    "..", "...", "==", ">=", "<=", "~=",
    "<number>", "<name>", "<string>", "<eof>",
    NULL
};


#define save_and_next(ls) (save(ls, ls->current), next(ls))


static void save (LexState *ls, int c) {
  Mbuffer *b = ls->buff;
  if (b->n + 1 > b->buffsize) {
    size_t newsize;
    if (b->buffsize >= MAX_SIZET/2)
      luaX_lexerror(ls, "lexical element too long", 0);
    newsize = b->buffsize * 2;
    luaZ_resizebuffer(ls->L, b, newsize);
  }
  b->buffer[b->n++] = cast(char, c);
}


void luaX_init (lua_State *L) {
  int i;
  for (i=0; i<NUM_RESERVED; i++) {
    TString *ts = luaS_new(L, luaX_tokens[i]);
    luaS_fix(ts);  /* reserved words are never collected */
    lua_assert(strlen(luaX_tokens[i])+1 <= TOKEN_LEN);
    ts->tsv.reserved = cast_byte(i+1);  /* reserved word */
  }
}


#define MAXSRC          80


const char *luaX_token2str (LexState *ls, int token) {
  if (token < FIRST_RESERVED) {
    lua_assert(token == cast(unsigned char, token));
    return (iscntrl(token)) ? luaO_pushfstring(ls->L, "char(%d)", token) :
                              luaO_pushfstring(ls->L, "%c", token);
  }
  else
    return luaX_tokens[token-FIRST_RESERVED];
}


static const char *txtToken (LexState *ls, int token) {
  switch (token) {
    case TK_NAME:
    case TK_STRING:
    case TK_NUMBER:
      save(ls, '\0');
      return luaZ_buffer(ls->buff);
    default:
      return luaX_token2str(ls, token);
  }
}


void luaX_lexerror (LexState *ls, const char *msg, int token) {
  char buff[MAXSRC];
  luaO_chunkid(buff, getstr(ls->source), MAXSRC);
  msg = luaO_pushfstring(ls->L, "%s:%d: %s", buff, ls->linenumber, msg);
  if (token)
    luaO_pushfstring(ls->L, "%s near " LUA_QS, msg, txtToken(ls, token));
  luaD_throw(ls->L, LUA_ERRSYNTAX);
}


void luaX_syntaxerror (LexState *ls, const char *msg) {
  luaX_lexerror(ls, msg, ls->t.token);
}


TString *luaX_newstring (LexState *ls, const char *str, size_t l) {
  lua_State *L = ls->L;
  TString *ts = luaS_newlstr(L, str, l);
  TValue *o = luaH_setstr(L, ls->fs->h, ts);  /* entry for `str' */
  if (ttisnil(o))
    setbvalue(o, 1);  /* make sure `str' will not be collected */
  return ts;
}


static void inclinenumber (LexState *ls) {
  int old = ls->current;
  lua_assert(currIsNewline(ls));
  next(ls);  /* skip `\n' or `\r' */
  if (currIsNewline(ls) && ls->current != old)
    next(ls);  /* skip `\n\r' or `\r\n' */
  if (++ls->linenumber >= MAX_INT)
    luaX_syntaxerror(ls, "chunk has too many lines");
}


static void setinput (lua_State *L, LexState *ls, ZIO *z, TString *source) {
  ls->decpoint = '.';
  ls->L = L;
  ls->lookahead.token = TK_EOS;  /* no look-ahead token */
  ls->z = z;
  ls->fs = NULL;
  ls->linenumber = 1;
  ls->lastline = 1;
  ls->source = source;
  luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER);  /* initialize buffer */
  next(ls);  /* read first char */
}



/*
** =======================================================
** LEXICAL ANALYZER
** =======================================================
*/



static int check_next (LexState *ls, const char *set) {
  if (!strchr(set, ls->current))
    return 0;
  save_and_next(ls);
  return 1;
}


static void buffreplace (LexState *ls, char from, char to) {
  size_t n = luaZ_bufflen(ls->buff);
  char *p = luaZ_buffer(ls->buff);
  while (n--)
    if (p[n] == from) p[n] = to;
}


static void trydecpoint (LexState *ls, SemInfo *seminfo) {
  /* format error: try to update decimal point separator */
  struct lconv *cv = localeconv();
  char old = ls->decpoint;
  ls->decpoint = (cv ? cv->decimal_point[0] : '.');
  buffreplace(ls, old, ls->decpoint);  /* try updated decimal separator */
  if (!luaO_str2d(luaZ_buffer(ls->buff), &seminfo->r)) {
    /* format error with correct decimal point: no more options */
    buffreplace(ls, ls->decpoint, '.');  /* undo change (for error
message) */
    luaX_lexerror(ls, "malformed number", TK_NUMBER);
  }
}


/* LUA_NUMBER */
static void read_numeral (LexState *ls, SemInfo *seminfo) {
  lua_assert(isdigit(ls->current));
  do {
    save_and_next(ls);
  } while (isdigit(ls->current) || ls->current == '.');
  if (check_next(ls, "Ee"))  /* `E'? */
    check_next(ls, "+-");  /* optional exponent sign */
  while (isalnum(ls->current) || ls->current == '_')
    save_and_next(ls);
  save(ls, '\0');
  buffreplace(ls, '.', ls->decpoint);  /* follow locale for decimal point */
  if (!luaO_str2d(luaZ_buffer(ls->buff), &seminfo->r))  /* format error? */
    trydecpoint(ls, seminfo); /* try to update decimal point separator */
}


static int skip_sep (LexState *ls) {
  int count = 0;
  int s = ls->current;
  lua_assert(s == '[' || s == ']');
  save_and_next(ls);
  while (ls->current == '=') {
    save_and_next(ls);
    count++;
  }
  return (ls->current == s) ? count : (-count) - 1;
}


static void read_long_string (LexState *ls, SemInfo *seminfo, int sep) {
  int cont = 0;
  (void)(cont);  /* avoid warnings when `cont' is not used */
  save_and_next(ls);  /* skip 2nd `[' */
  if (currIsNewline(ls))  /* string starts with a newline? */
    inclinenumber(ls);  /* skip it */
  for (;;) {
    switch (ls->current) {
      case EOZ:
        luaX_lexerror(ls, (seminfo) ? "unfinished long string" :
                                   "unfinished long comment", TK_EOS);
        break;  /* to avoid warnings */
#if defined(LUA_COMPAT_LSTR)
      case '[': {
        if (skip_sep(ls) == sep) {
          save_and_next(ls);  /* skip 2nd `[' */
          cont++;
#if LUA_COMPAT_LSTR == 1
          if (sep == 0)
            luaX_lexerror(ls, "nesting of [[...]] is deprecated", '[');
#endif
        }
        break;
      }
#endif
      case ']': {
        if (skip_sep(ls) == sep) {
          save_and_next(ls);  /* skip 2nd `]' */
#if defined(LUA_COMPAT_LSTR) && LUA_COMPAT_LSTR == 2
          cont--;
          if (sep == 0 && cont >= 0) break;
#endif
          goto endloop;
        }
        break;
      }
      case '\n':
      case '\r': {
        save(ls, '\n');
        inclinenumber(ls);
        if (!seminfo) luaZ_resetbuffer(ls->buff);  /* avoid wasting space */
        break;
      }
      default: {
        if (seminfo) save_and_next(ls);
        else next(ls);
      }
    }
  } endloop:
  if (seminfo)
    seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + (2 + sep),
                                     luaZ_bufflen(ls->buff) - 2*(2 + sep));
}


static void read_string (LexState *ls, int del, SemInfo *seminfo) {
  save_and_next(ls);
  while (ls->current != del) {
    switch (ls->current) {
      case EOZ:
        luaX_lexerror(ls, "unfinished string", TK_EOS);
        continue;  /* to avoid warnings */
      case '\n':
      case '\r':
        luaX_lexerror(ls, "unfinished string", TK_STRING);
        continue;  /* to avoid warnings */
      case '\\': {
        int c;
        next(ls);  /* do not save the `\' */
        switch (ls->current) {
          case 'a': c = '\a'; break;
          case 'b': c = '\b'; break;
          case 'f': c = '\f'; break;
          case 'n': c = '\n'; break;
          case 'r': c = '\r'; break;
          case 't': c = '\t'; break;
          case 'v': c = '\v'; break;
          case '\n':  /* go through */
          case '\r': save(ls, '\n'); inclinenumber(ls); continue;
          case EOZ: continue;  /* will raise an error next loop */
          default: {
            if (!isdigit(ls->current))
              save_and_next(ls);  /* handles \\, \", \', and \? */
            else {  /* \xxx */
              int i = 0;
              c = 0;
              do {
                c = 10*c + (ls->current-'0');
                next(ls);
              } while (++i<3 && isdigit(ls->current));
              if (c > UCHAR_MAX)
                luaX_lexerror(ls, "escape sequence too large", TK_STRING);
              save(ls, c);
            }
            continue;
          }
        }
        save(ls, c);
        next(ls);
        continue;
      }
      default:
        save_and_next(ls);
    }
  }
  save_and_next(ls);  /* skip delimiter */
  seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + 1,
                                   luaZ_bufflen(ls->buff) - 2);
}


static int llex (LexState *ls, SemInfo *seminfo) {
  luaZ_resetbuffer(ls->buff);
  for (;;) {
    switch (ls->current) {
      case '\n':
      case '\r': {
        inclinenumber(ls);
        continue;
      }
      case '-': {
        next(ls);
        if (ls->current != '-') return '-';
        /* else is a comment */
        next(ls);
        if (ls->current == '[') {
          int sep = skip_sep(ls);
          luaZ_resetbuffer(ls->buff);  /* `skip_sep' may dirty the buffer */
          if (sep >= 0) {
            read_long_string(ls, NULL, sep);  /* long comment */
            luaZ_resetbuffer(ls->buff);
            continue;
          }
        }
        /* else short comment */
        while (!currIsNewline(ls) && ls->current != EOZ)
          next(ls);
        continue;
      }
      case '[': {
        int sep = skip_sep(ls);
        if (sep >= 0) {
          read_long_string(ls, seminfo, sep);
          return TK_STRING;
        }
        else if (sep == -1) return '[';
        else luaX_lexerror(ls, "invalid long string delimiter", TK_STRING);
      }
      case '=': {
        next(ls);
        if (ls->current != '=') return '=';
        else { next(ls); return TK_EQ; }
      }
      case '<': {
        next(ls);
        if (ls->current != '=') return '<';
        else { next(ls); return TK_LE; }
      }
      case '>': {
        next(ls);
        if (ls->current != '=') return '>';
        else { next(ls); return TK_GE; }
      }
      case '~': {
        next(ls);
        if (ls->current != '=') return '~';
        else { next(ls); return TK_NE; }
      }
      case '"':
      case '\'': {
        read_string(ls, ls->current, seminfo);
        return TK_STRING;
      }
      case '.': {
        save_and_next(ls);
        if (check_next(ls, ".")) {
          if (check_next(ls, "."))
            return TK_DOTS;   /* ... */
          else return TK_CONCAT;   /* .. */
        }
        else if (!isdigit(ls->current)) return '.';
        else {
          read_numeral(ls, seminfo);
          return TK_NUMBER;
        }
      }
      case EOZ: {
        return TK_EOS;
      }
      default: {
        if (isspace(ls->current)) {
          lua_assert(!currIsNewline(ls));
          next(ls);
          continue;
        }
        else if (isdigit(ls->current)) {
          read_numeral(ls, seminfo);
          return TK_NUMBER;
        }
        else if (isalpha(ls->current) || ls->current == '_') {
          /* identifier or reserved word */
          TString *ts;
          do {
            save_and_next(ls);
          } while (isalnum(ls->current) || ls->current == '_');
          ts = luaX_newstring(ls, luaZ_buffer(ls->buff),
                                  luaZ_bufflen(ls->buff));
          if (ts->tsv.reserved > 0)  /* reserved word? */
            return ts->tsv.reserved - 1 + FIRST_RESERVED;
          else {
            seminfo->ts = ts;
            return TK_NAME;
          }
        }
        else {
          int c = ls->current;
          next(ls);
          return c;  /* single-char tokens (+ - / ...) */
        }
      }
    }
  }
}

//#include "proxy.c"
/* TOKEN FILTERS: */

#define USE_TOKEN_FILTERS

#ifdef USE_TOKEN_FILTERS

	#define FILTER	"FILTER"

	static int gettoken(lua_State *L)
	{
	 LexState *ls=lua_touserdata(L,lua_upvalueindex(1));
	 SemInfo seminfo;
	 int c;
	 if (ls!=NULL && ls->fs==NULL) return0;
	 if (ls==NULL)
	 {
	  c=TK_EOS;
	  lua_pushinteger(L,0);
	 }
	 else
	 {
	  c=llex(ls,&seminfo);
	  lua_pushinteger(L,ls->linenumber);
	 }
	 if (c<FIRST_RESERVED)
	 {
	  char s=c;
	  lua_pushlstring(L,&s,1);
	 }
	 else
	  lua_pushstring(L,luaX_tokens[c-FIRST_RESERVED]);
	 if (c==TK_NAME || c==TK_STRING)
	  lua_pushlstring(L,getstr(seminfo.ts),seminfo.ts->tsv.len);
	 elseif (c==TK_NUMBER)
	  lua_pushnumber(L,seminfo.r);
	 else
	  lua_pushnil(L);
	 if (c==TK_EOS && ls!=NULL)
	 {
	  lua_pushnil(L);
	  lua_replace(L,lua_upvalueindex(1));
	 }
	 return3;
	}

	void luaX_setinput(lua_State *L, LexState *ls, ZIO *z, TString *source)
	{
	 setinput(L,ls,z,source);
	 lua_getglobal(L,FILTER);
	 if (lua_isnil(L,-1))
	  lua_pop(L,1);
	 else
	 {
	  lua_pushlightuserdata(L,ls);
	  lua_pushcclosure(L,gettoken,1);
	  lua_pushlstring(L,getstr(source),source->tsv.len);
	  lua_call(L,2,0);
	 }
	}

	static int nexttoken(LexState *ls, SemInfo *seminfo)
	{
	 lua_State *L=ls->L;
	 lua_getglobal(L,FILTER);
	 if (lua_isnil(L,-1))
	 {
	  lua_pop(L,1);
	  return llex(ls,seminfo);
	 }
	 else
	 {
	  int c;
	  const char *token;
	  lua_call(L,0,3);
	  token=lua_tostring(L,-2);
	  if (token==NULL)
	   c=TK_EOS;
	  else
	  {
	   int i;
	   c=-1;
	   for (i=0; luaX_tokens[i]; i++)
	   {
		if (strcmp(token,luaX_tokens[i])==0)
		{
		 c=i+FIRST_RESERVED;
		 break;
		}
	   }
	   if (c==-1)
		c=token[0];
	   elseif (c==TK_NAME || c==TK_STRING)
	   {
		if (lua_tostring(L,-1)==NULL)
		 seminfo->ts=luaS_newliteral(L,"?");
		else
		 seminfo->ts=luaS_newlstr(L,lua_tostring(L,-1),lua_strlen(L,-1));
	   }
	   elseif (c==TK_NUMBER)
		seminfo->r=lua_tonumber(L,-1);
	  }
	  ls->linenumber=lua_tointeger(L,-3);
	  lua_pop(L,3);
	  return c;
	 }
	}

	#define llex nexttoken

#endif

/* TOKEN FILTERS END */

void luaX_next (LexState *ls) {
  ls->lastline = ls->linenumber;
  if (ls->lookahead.token != TK_EOS) {  /* is there a look-ahead token? */
    ls->t = ls->lookahead;  /* use this one */
    ls->lookahead.token = TK_EOS;  /* and discharge it */
  }
  else
    ls->t.token = llex(ls, &ls->t.seminfo);  /* read next token */
}


void luaX_lookahead (LexState *ls) {
  lua_assert(ls->lookahead.token == TK_EOS);
  ls->lookahead.token = llex(ls, &ls->lookahead.seminfo);
}