Re: lauxlib.c : luaL_loadfilex BUG : can loose OS error, fixed

[Massimo Sala <massimo.sala.71@...>]

It was thus said that the Great Sean Conner once stated:

> I think it was intentional that errno isn't used in this function.

The function already used errno, look at the source code: luaL_loadfilex calls errfile

If you don't read the source, you cannot understand the subtle bug I fixed.

M

On Tue, 12 May 2020 at 00:04, Sean Conner <sean@conman.org> wrote:

It was thus said that the Great Massimo Sala once stated:
> Current code of the function, last lines:
> ...
>   readstatus = ferror(lf.f);
>   if (filename) fclose(lf.f);  /* close file (even in case of errors) */
>   if (readstatus) {
>     lua_settop(L, fnameindex);  /* ignore results from 'lua_load' */
>     return errfile(L, "read", fnameindex);
>   }
>   lua_remove(L, fnameindex);
>   return status;
> }
>
>
> On some OS fclose could change errno. See for example
> http://man7.org/linux/man-pages/man3/fclose.3.html
>        The fclose() function may also fail and set errno for any of the
>        errors specified for the routines close(2), write(2), or fflush(3).
>

  The C standard (C89, C99, and C11 have the same language) states this
about errno:

        The value of errno may be set to nonzero by a library function call
        whether or not there is an error, provided the use of errno is not
        documented in the description of the function in this International
        Standard.

fclose() is not documented as setting errno, so it's up to the
implementation (not even the operating system---the C standard library
itself) whether fclose() sets errno or not.  I think it was intentional that
errno isn't used in this function.

  -spc
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