From: Paul Brannan <pbrannan@...>
Date: 2008-01-09T06:35:59+09:00
Subject: Re: Embedding 1.9

On Wed, Jan 09, 2008 at 02:04:03AM +0900, Dave Thomas wrote:
> int main(int argc, char **argv) {
>   VALUE result;
> 
>   ruby_sysinit(&argc, &argv);
>   RUBY_INIT_STACK;
>   ruby_init();
>   ruby_init_loadpath();
> 
>   rb_require("sum.rb");
>   rb_eval_string("$summer = Summer.new");
>   rb_eval_string("$result = $summer.sum(10)");
>   result = rb_gv_get("result");
>   printf("Result = %d\n", NUM2INT(result));
>   ruby_finalize();
>   exit(0);
> }

Before I added sum.rb:

  class Summer
    def sum(*args)
      args.inject { |sum, x| sum + x }
    end
  end

I was getting a segfault running your example:

  [pbrannan@zaphod embed]$ ./embed
  <dummy toplevel>:17: [BUG] Segmentation fault
  ruby 1.9.0 (2008-01-04 revision 0) [i686-linux]
  
Your example should catch exceptions:
  
  VALUE embeded(VALUE ignore)
  {
    VALUE result;
    rb_require("sum.rb");
    rb_eval_string("$summer = Summer.new");
    rb_eval_string("$result = $summer.sum(10)");
    result = rb_gv_get("result");
    printf("Result = %d\n", NUM2INT(result));
    return Qnil;
  }
  
  int main(int argc, char **argv) {
    int state;
  
    ruby_sysinit(&argc, &argv);
    RUBY_INIT_STACK;
    ruby_init();
    ruby_options(argc, argv);
  
    rb_protect(embeded, Qnil, &state);
    return ruby_cleanup(state);
  }

to prevent the segfault:

  [pbrannan@zaphod embed]$ mv sum.rb sum_bk.rb
  [pbrannan@zaphod embed]$ ./embed 
  ruby 1.9.0 (2008-01-08 revision 0) [i686-linux]
  <dummy toplevel>:17: no such file to load -- sum.rb (LoadError)

I also removed the call to exit(0) and replaced ruby_init_loadpath()
with ruby_options().

I think there's still some work left to do, because:
  - the filename is wrong ("dummy toplevel").
  - TOPLEVEL_BINDING is undefined
  - NameError exceptions aren't getting caught (the program just exits)
  - I can't require shared objects (rb_require("socket") gives an error
    about rb_eRuntimeError being undefined)

I don't know which of these are bugs in my code and which are bugs in
the interpreter.

BTW, how are you determining which options to pass to the compiler/linker?  I
feel there should be a better way than what I'm doing:

  ruby_config() { ruby1.9 -rrbconfig -e "puts Config::CONFIG['$1']" | grep -v "ruby 1.9.0"; }
  gcc embed.c -o embed \
  -I `ruby_config rubyhdrdir` \
  -I `ruby_config rubyhdrdir`/`ruby_config arch` \
  -L `ruby_config libdir` \
  `ruby_config LDFLAGS` \
  `ruby_config LIBS` \
  `ruby_config LIBRUBYARG`

I'm unsure whether I should be using LDFLAGS above, since it contains
the string "-L.", which seems wrong.

Paul