dump

/*
 * call-seq:
 *      dump( obj [, anIO] , limit=--1 ) => anIO
 *
 * Serializes obj and all descendent objects. If anIO is
 * specified, the serialized data will be written to it, otherwise the
 * data will be returned as a String. If limit is specified, the
 * traversal of subobjects will be limited to that depth. If limit is
 * negative, no checking of depth will be performed.
 *
 *     class Klass
 *       def initialize(str)
 *         @str = str
 *       end
 *       def sayHello
 *         @str
 *       end
 *     end
 *
 * (produces no output)
 *
 *     o = Klass.new("hello\n")
 *     data = Marshal.dump(o)
 *     obj = Marshal.load(data)
 *     obj.sayHello   #=> "hello\n"
 */
static VALUE
marshal_dump(argc, argv)
    int argc;
    VALUE* argv;
{
    VALUE obj, port, a1, a2;
    int limit = -1;
    struct dump_arg arg;
    struct dump_call_arg c_arg;

    port = Qnil;
    rb_scan_args(argc, argv, "12", &obj, &a1, &a2);
    if (argc == 3) {
        if (!NIL_P(a2)) limit = NUM2INT(a2);
        if (NIL_P(a1)) goto type_error;
        port = a1;
    }
    else if (argc == 2) {
        if (FIXNUM_P(a1)) limit = FIX2INT(a1);
        else if (NIL_P(a1)) goto type_error;
        else port = a1;
    }
    arg.dest = 0;
    arg.symbols = st_init_numtable();
    arg.data    = st_init_numtable();
    arg.taint   = Qfalse;
    arg.str = rb_str_buf_new(0);
    RBASIC(arg.str)->klass = 0;
    arg.wrapper = Data_Wrap_Struct(rb_cData, mark_dump_arg, 0, &arg);
    if (!NIL_P(port)) {
        if (!rb_respond_to(port, s_write)) {
          type_error:
            rb_raise(rb_eTypeError, "instance of IO needed");
        }
        arg.dest = port;
        if (rb_respond_to(port, s_binmode)) {
            rb_funcall2(port, s_binmode, 0, 0);
            check_dump_arg(&arg, s_binmode);
        }
    }
    else {
        port = arg.str;
    }

    c_arg.obj   = obj;
    c_arg.arg   = &arg;
    c_arg.limit = limit;

    w_byte(MARSHAL_MAJOR, &arg);
    w_byte(MARSHAL_MINOR, &arg);

    rb_ensure(dump, (VALUE)&c_arg, dump_ensure, (VALUE)&arg);
    RBASIC(arg.str)->klass = rb_cString;

    return port;
}