Re: os.execute is scary; Jay rants about strings again (was Re: [ANNOUNCE] lua stdlibs release: now Lua 5 compatible)

[Jay Carlson <nop@...>]

Reuben Thomas wrote:

> On Fri, 30 Jan 2004, Jay Carlson wrote:
>
>
> > On Fri, 30 Jan 2004, Jay Carlson wrote:
> >
> >
> > > On Wed, 28 Jan 2004, Reuben Thomas wrote:
> >
> > > > This is the main objection to what I propose above. What can't you do
> > > > conveniently with exec and glob?
> >
> > Oh right, I forgot:
> >
> >  f = os.popen("mipsel-linux-objdump --syms --section="..section..
> > 	" --start-address="..hex(start).." "..objfilename)
> >  for l in f:lines() do
> >    _, _, etc = string.find(l, "^(%x%x%x%x%x%x%x%x) [^l] ...")
> >    ...
> >  end

> What's wrong with pipe, fork and exec? (With a simplifying wrapper,
> obviously.)

To make things clearer, what I claim to want to write there is:

  f = myos.popen("mipsel-linux-objdump", "--syms",
    "--section="..section, "--start-address="..hex(start),
    objfilename)

Right now, external libraries can't create file handles.  So if I write 
an external popen(argv, env), I have to duplicate the infrastructure in 
liolib.c.  The only way I can write myos.popen is in terms of the 
existing io functions, building a complicated command line for io.popen.

Hey, Lua maintainers: this could be a fix for it:

liolib.c:
int
luaIO_filecreate(lua_State *L, FILE *f)
{
   FILE **pf = newfile(L);
   *pf = f;
   return 1;
}

This also lets me easily write stuff like fdopen, which is not ANSI C, 
but widely supported, even outside POSIX.

Jay