1package pty
2
3import (
4	"errors"
5	"os"
6	"syscall"
7	"unsafe"
8)
9
10func open() (pty, tty *os.File, err error) {
11	p, err := os.OpenFile("/dev/ptmx", os.O_RDWR, 0)
12	if err != nil {
13		return nil, nil, err
14	}
15
16	sname, err := ptsname(p)
17	if err != nil {
18		return nil, nil, err
19	}
20
21	err = grantpt(p)
22	if err != nil {
23		return nil, nil, err
24	}
25
26	err = unlockpt(p)
27	if err != nil {
28		return nil, nil, err
29	}
30
31	t, err := os.OpenFile(sname, os.O_RDWR, 0)
32	if err != nil {
33		return nil, nil, err
34	}
35	return p, t, nil
36}
37
38func ptsname(f *os.File) (string, error) {
39	n := make([]byte, _IOC_PARM_LEN(syscall.TIOCPTYGNAME))
40
41	err := ioctl(f.Fd(), syscall.TIOCPTYGNAME, uintptr(unsafe.Pointer(&n[0])))
42	if err != nil {
43		return "", err
44	}
45
46	for i, c := range n {
47		if c == 0 {
48			return string(n[:i]), nil
49		}
50	}
51	return "", errors.New("TIOCPTYGNAME string not NUL-terminated")
52}
53
54func grantpt(f *os.File) error {
55	return ioctl(f.Fd(), syscall.TIOCPTYGRANT, 0)
56}
57
58func unlockpt(f *os.File) error {
59	return ioctl(f.Fd(), syscall.TIOCPTYUNLK, 0)
60}
61