1package pty 2 3import ( 4 "errors" 5 "os" 6 "syscall" 7 "unsafe" 8) 9 10func open() (pty, tty *os.File, err error) { 11 pFD, err := syscall.Open("/dev/ptmx", syscall.O_RDWR|syscall.O_CLOEXEC, 0) 12 if err != nil { 13 return nil, nil, err 14 } 15 p := os.NewFile(uintptr(pFD), "/dev/ptmx") 16 // In case of error after this point, make sure we close the ptmx fd. 17 defer func() { 18 if err != nil { 19 _ = p.Close() // Best effort. 20 } 21 }() 22 23 sname, err := ptsname(p) 24 if err != nil { 25 return nil, nil, err 26 } 27 28 if err := grantpt(p); err != nil { 29 return nil, nil, err 30 } 31 32 if err := unlockpt(p); err != nil { 33 return nil, nil, err 34 } 35 36 t, err := os.OpenFile(sname, os.O_RDWR, 0) 37 if err != nil { 38 return nil, nil, err 39 } 40 return p, t, nil 41} 42 43func ptsname(f *os.File) (string, error) { 44 n := make([]byte, _IOC_PARM_LEN(syscall.TIOCPTYGNAME)) 45 46 err := ioctl(f.Fd(), syscall.TIOCPTYGNAME, uintptr(unsafe.Pointer(&n[0]))) 47 if err != nil { 48 return "", err 49 } 50 51 for i, c := range n { 52 if c == 0 { 53 return string(n[:i]), nil 54 } 55 } 56 return "", errors.New("TIOCPTYGNAME string not NUL-terminated") 57} 58 59func grantpt(f *os.File) error { 60 return ioctl(f.Fd(), syscall.TIOCPTYGRANT, 0) 61} 62 63func unlockpt(f *os.File) error { 64 return ioctl(f.Fd(), syscall.TIOCPTYUNLK, 0) 65} 66