From: nobu.nokada@...
Date: 2005-05-18T10:50:28+09:00
Subject: Re: IRB, Mac OS X, command-line require via "-r" and Bus Errors

Hi,

At Wed, 18 May 2005 06:40:31 +0900,
Jonathan Paisley wrote in [ruby-talk:142962]:
> I'm not entirely sure what you mean here. The CFRuntime code removes -AppleLanguages 
> arguments from the command line, but the code that does it crashes if there are
> NULLs present. We see the error if a ruby script calls set_arg0 before this happens.
> set_arg0 sets argv[0], and sets argv[1 to argc-1] to NULL.

The code "around line 720" you posted doesn't remove
-AppleLanguages, but copies it to __CFAppleLanguages.  So I
guess it might be used later if it was given.

> One of my suggestions was: in set_arg0 use empty strings ("") instead
> of NULL values in set_arg0. This would prevent the crash.
> 
> An alternative would be just to link ruby with the CoreFoundation framework. That way,
> the CFRuntime initialisation code should get executed before ruby initialises, and
> the problem goes away.

Does the initialization run just once in the whole process?

> > What about this?
> > 
> > void
> > ruby_sysinit(argc, argv)
> >     int *argc;
> >     char ***argv;
> > {
> > #if defined(__APPLE__) && (defined(__MACH__) || defined(__DARWIN__))
> >     int i, n = *argc, len = 0;
> >     char **v1 = *argv, **v2 = ALLOC_N(char*, n + 1);
> >     MEMCPY(v2, v1, char*, n);
> >     v2[n] = 0;
> >     for (i = 0; i < n; ++i) {
> > 	v1[i] = strdup(v1[i]);
> >     }
> >     *argv = v2;
> > #elif defined(__MACOS__) && defined(__MWERKS__)
> >     *argc = ccommand(argv);
> > #endif
> > }
> 
> The problem with this is that it causes set_arg0 to not have the desired effect.
> 
> set_arg0 is designed to change the process name, as it appears in 'ps' output. 
> To do this, it's necessary to overwrite the existing argument strings.
> Note: what I mean here is overwriting the character data in the existing
> strings, and not changing string pointers in the argv array. 'ps' (or in
> kernel process info, depending on OS) reads directly from the argument
> strings, not going through any pointers in an argv array.
> 
> The upshot is that changing argv for ruby in the proposed ruby_sysinit
> means that a later set_arg0 will not change the necessary kernel-known
> arguments. 

No, it duplicates the argument strings and remains them in the
original argv (i.e., pointed from *_NSGetArgv()), but let the
entire string area to be pointed by newly allocated argv, which
is returned to the caller.

-- 
Nobu Nakada