gistfile1.h

static VALUE
io_write(VALUE io, SEL sel, VALUE to_write)
{
    rb_io_t *io_struct;
    VALUE to_write;
    UInt8 *buffer;
    CFIndex length;
    
    rb_secure(4);
    
    io_struct = ExtractIOStruct(io);
    rb_io_assert_writable(io_struct);
    // TODO: Account for the port not being IO, use funcall to call .write()
    // instead.
    to_write = rb_obj_as_string(to_write);
    buffer = (UInt8*)rb_str_byteptr(to_write);
    length = (CFIndex)rb_str_bytelen(to_write);
    
    if(length == 0) {
        return INT2FIX(0);
    }
    return LONG2FIX(CFWriteStreamWrite(io_struct->writeStream, buffer, length));
}