1//go:build freebsd
2//+build freebsd
3
4package pty
5
6import (
7	"errors"
8	"os"
9	"syscall"
10	"unsafe"
11)
12
13func posixOpenpt(oflag int) (fd int, err error) {
14	r0, _, e1 := syscall.Syscall(syscall.SYS_POSIX_OPENPT, uintptr(oflag), 0, 0)
15	fd = int(r0)
16	if e1 != 0 {
17		err = e1
18	}
19	return fd, err
20}
21
22func open() (pty, tty *os.File, err error) {
23	fd, err := posixOpenpt(syscall.O_RDWR | syscall.O_CLOEXEC)
24	if err != nil {
25		return nil, nil, err
26	}
27	p := os.NewFile(uintptr(fd), "/dev/pts")
28	// In case of error after this point, make sure we close the pts fd.
29	defer func() {
30		if err != nil {
31			_ = p.Close() // Best effort.
32		}
33	}()
34
35	sname, err := ptsname(p)
36	if err != nil {
37		return nil, nil, err
38	}
39
40	t, err := os.OpenFile("/dev/"+sname, os.O_RDWR, 0)
41	if err != nil {
42		return nil, nil, err
43	}
44	return p, t, nil
45}
46
47func isptmaster(fd uintptr) (bool, error) {
48	err := ioctl(fd, syscall.TIOCPTMASTER, 0)
49	return err == nil, err
50}
51
52var (
53	emptyFiodgnameArg fiodgnameArg
54	ioctlFIODGNAME    = _IOW('f', 120, unsafe.Sizeof(emptyFiodgnameArg))
55)
56
57func ptsname(f *os.File) (string, error) {
58	master, err := isptmaster(f.Fd())
59	if err != nil {
60		return "", err
61	}
62	if !master {
63		return "", syscall.EINVAL
64	}
65
66	const n = _C_SPECNAMELEN + 1
67	var (
68		buf = make([]byte, n)
69		arg = fiodgnameArg{Len: n, Buf: (*byte)(unsafe.Pointer(&buf[0]))}
70	)
71	if err := ioctl(f.Fd(), ioctlFIODGNAME, uintptr(unsafe.Pointer(&arg))); err != nil {
72		return "", err
73	}
74
75	for i, c := range buf {
76		if c == 0 {
77			return string(buf[:i]), nil
78		}
79	}
80	return "", errors.New("FIODGNAME string not NUL-terminated")
81}
82