/*
 * Returns bytes of data in the input buffer. Normally, returns 0.
 */
static VALUE
rb_zstream_avail_in(obj)
    VALUE obj;
{
    struct zstream *z;
    Data_Get_Struct(obj, struct zstream, z);
    return INT2FIX(NIL_P(z->input) ? 0 : (int)(RSTRING(z->input)->len));
}