Object
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Returns number of bytes that can be read without blocking. Returns zero if no information available.
 
               static VALUE
io_nread(VALUE io)
{
    rb_io_t *fptr = NULL;
    ioctl_arg n;
    GetOpenFile(io, fptr);
    rb_io_check_readable(fptr);
    int len = rb_io_read_pending(fptr);
    if (len > 0) return INT2FIX(len);
    if (!FIONREAD_POSSIBLE_P(fptr->fd)) return INT2FIX(0);
    if (ioctl(fptr->fd, FIONREAD, &n)) return INT2FIX(0);
    if (n > 0) return ioctl_arg2num(n);
    return INT2FIX(0);
}
             
            Returns true if input available without blocking, or false.
 
               static VALUE
io_ready_p(VALUE io)
{
    rb_io_t *fptr;
    GetOpenFile(io, fptr);
    rb_io_check_readable(fptr);
    if (rb_io_read_pending(fptr)) return Qtrue;
    return io_wait_event(io, RUBY_IO_READABLE, RB_INT2NUM(0));
}
             
            Waits until the IO becomes ready for the specified events and returns the subset of events that become ready, or false when times out.
The events can be a bit mask of IO::READABLE, IO::WRITABLE or IO::PRIORITY.
Returns true immediately when buffered data is available.
Optional parameter mode is one of :read, :write, or :read_write (deprecated).
 
               static VALUE
io_wait(int argc, VALUE *argv, VALUE io)
{
    VALUE timeout = Qnil;
    rb_io_event_t events = 0;
    if (argc < 2 || (argc >= 2 && RB_SYMBOL_P(argv[1]))) {
        if (argc > 0) {
            timeout = argv[0];
        }
        for (int i = 1; i < argc; i += 1) {
            events |= wait_mode_sym(argv[i]);
        }
    }
    else if (argc == 2) {
        events = RB_NUM2UINT(argv[0]);
        if (argv[1] != Qnil) {
            timeout = argv[1];
        }
    }
    else {
        // TODO error
        return Qnil;
    }
    if (events == 0) {
        events = RUBY_IO_READABLE;
    }
    if (events & RUBY_IO_READABLE) {
        rb_io_t *fptr = NULL;
        RB_IO_POINTER(io, fptr);
        if (rb_io_read_pending(fptr)) {
            return Qtrue;
        }
    }
    return io_wait_event(io, events, timeout);
}
             
            Waits until IO is priority and returns true or false when times out.
 
               static VALUE
io_wait_priority(int argc, VALUE *argv, VALUE io)
{
    rb_io_t *fptr = NULL;
    RB_IO_POINTER(io, fptr);
    rb_io_check_readable(fptr);
    if (rb_io_read_pending(fptr)) return Qtrue;
    rb_check_arity(argc, 0, 1);
    VALUE timeout = argc == 1 ? argv[0] : Qnil;
    return io_wait_event(io, RUBY_IO_PRIORITY, timeout);
}
             
            Waits until IO is readable and returns true, or false when times out. Returns true immediately when buffered data is available.
 
               static VALUE
io_wait_readable(int argc, VALUE *argv, VALUE io)
{
    rb_io_t *fptr = NULL;
    RB_IO_POINTER(io, fptr);
    rb_io_check_readable(fptr);
    if (rb_io_read_pending(fptr)) return Qtrue;
    rb_check_arity(argc, 0, 1);
    VALUE timeout = (argc == 1 ? argv[0] : Qnil);
    return io_wait_event(io, RUBY_IO_READABLE, timeout);
}
             
            Waits until IO is writable and returns true or false when times out.
 
               static VALUE
io_wait_writable(int argc, VALUE *argv, VALUE io)
{
    rb_io_t *fptr = NULL;
    RB_IO_POINTER(io, fptr);
    rb_io_check_writable(fptr);
    rb_check_arity(argc, 0, 1);
    VALUE timeout = (argc == 1 ? argv[0] : Qnil);
    return io_wait_event(io, RUBY_IO_WRITABLE, timeout);
}