github.com/dolfly/pty@v1.2.1/pty_linux.go (about)

     1  //go:build linux
     2  //+build linux
     3  
     4  package pty
     5  
     6  import (
     7  	"os"
     8  	"strconv"
     9  	"syscall"
    10  	"unsafe"
    11  )
    12  
    13  func open() (pty, tty *os.File, err error) {
    14  	p, err := os.OpenFile("/dev/ptmx", os.O_RDWR, 0)
    15  	if err != nil {
    16  		return nil, nil, err
    17  	}
    18  	// In case of error after this point, make sure we close the ptmx fd.
    19  	defer func() {
    20  		if err != nil {
    21  			_ = p.Close() // Best effort.
    22  		}
    23  	}()
    24  
    25  	sname, err := ptsname(p)
    26  	if err != nil {
    27  		return nil, nil, err
    28  	}
    29  
    30  	if err := unlockpt(p); err != nil {
    31  		return nil, nil, err
    32  	}
    33  
    34  	t, err := os.OpenFile(sname, os.O_RDWR|syscall.O_NOCTTY, 0) //nolint:gosec // Expected Open from a variable.
    35  	if err != nil {
    36  		return nil, nil, err
    37  	}
    38  	return p, t, nil
    39  }
    40  
    41  func ptsname(f *os.File) (string, error) {
    42  	var n _C_uint
    43  	err := ioctl(f.Fd(), syscall.TIOCGPTN, uintptr(unsafe.Pointer(&n))) //nolint:gosec // Expected unsafe pointer for Syscall call.
    44  	if err != nil {
    45  		return "", err
    46  	}
    47  	return "/dev/pts/" + strconv.Itoa(int(n)), nil
    48  }
    49  
    50  func unlockpt(f *os.File) error {
    51  	var u _C_int
    52  	// use TIOCSPTLCK with a pointer to zero to clear the lock
    53  	return ioctl(f.Fd(), syscall.TIOCSPTLCK, uintptr(unsafe.Pointer(&u))) //nolint:gosec // Expected unsafe pointer for Syscall call.
    54  }