reading script from file: luaL_dofile inconsistencies

First of all, many compliments to the authors of Lua.

I have been learning LUA since Saturday.

I am trying to do my best to improve LUA; I hope not to waste your time, I don't know if you have already talked about these topics.

I read the manual and I look at LUA source code.

Please correct me, I take the manual as the public, formal specification of LUA.

Two questions:

1) return code

The manual says " It returns false if there are no errors or true in case of errors."

I read the source code (both 5.3 and 5.4) and I am trying to follow all the return paths.

lauxlib.h

#define luaL_dofile(L, fn) (luaL_loadfile(L, fn) || lua_pcall(L, 0, LUA_MULTRET, 0))

#define luaL_loadfile(L,f) luaL_loadfilex(L,f,NULL)

lauxlib.c

luaL_loadfilex

if (lf.f == NULL) return errfile(L, "reopen", fnameindex);

errfile

return LUA_ERRFILE;

lauxlib.h

#define LUA_ERRFILE (LUA_ERRERR+1)

lua.h

#define LUA_ERRERR 6

So it seems to me the return values can - at least - be 0, 1, 7.

Am I right ?

2) loading compiled files

luaL_dofile can load plain source code and compiled scripts (bytecode).

I have to check users don't pass filenames of compiled scripts.

From what I see, there isn't any LUA library to help this and the common solutions is:

- open the file in binary mode

- read the first byte: the value ESC marks a binary script (lua.h : LUA_SIGNATURE "\x1bLua")

I want to be sure so I dig into the source files:

lauxlib.c

luaL_loadfilex

Reading the code, it seems the function reads the file and checks for

- BOM ?

- 1st line: comment ?

before this check

if (c == LUA_SIGNATURE[0] && filename) { /* binary file? */

So luaL_loadfilex accepts binary files even if they start with BOM and/or a comment. I tested this, it works indeed.

Considerations:

2a) The manual doesn't say anything about this strange possibility

2b) For what I see around, users don't know this; so to "block" the execution of compiled scripts they code the naive and insufficient

load the file and check the first byte: ESC ?

I don't know if this is the intended behaviour or just a side effect of using luaL_loadfilex to load both for plain text and bytecode scripts..

I propose this change: the binary file have to start, at offset 0, with LUA_SIGNATURE.

What do you think ?

Best regards, Massimo