48 lines
1.6 KiB
Go
48 lines
1.6 KiB
Go
|
//go:build linux
|
||
|
|
// +build linux
|
||
|
|
|
||
|
|
package chroot
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"os"
|
||
|
|
"syscall"
|
||
|
|
"unsafe"
|
||
|
|
|
||
|
|
"golang.org/x/sys/unix"
|
||
|
|
)
|
||
|
|
|
||
|
|
// Open a PTY using the /dev/ptmx device. The main advantage of using
|
||
|
|
// this instead of posix_openpt is that it avoids cgo.
|
||
|
|
func getPtyDescriptors() (int, int, error) {
|
||
|
|
// Create a pseudo-terminal -- open a copy of the master side.
|
||
|
|
controlFd, err := unix.Open("/dev/ptmx", os.O_RDWR, 0600)
|
||
|
|
if err != nil {
|
||
|
|
return -1, -1, fmt.Errorf("error opening PTY master using /dev/ptmx: %v", err)
|
||
|
|
}
|
||
|
|
// Set the kernel's lock to "unlocked".
|
||
|
|
locked := 0
|
||
|
|
if result, _, err := unix.Syscall(unix.SYS_IOCTL, uintptr(controlFd), unix.TIOCSPTLCK, uintptr(unsafe.Pointer(&locked))); int(result) == -1 {
|
||
|
|
return -1, -1, fmt.Errorf("error unlocking PTY descriptor: %v", err)
|
||
|
|
}
|
||
|
|
// Get a handle for the other end.
|
||
|
|
ptyFd, _, err := unix.Syscall(unix.SYS_IOCTL, uintptr(controlFd), unix.TIOCGPTPEER, unix.O_RDWR|unix.O_NOCTTY)
|
||
|
|
if int(ptyFd) == -1 {
|
||
|
|
if errno, isErrno := err.(syscall.Errno); !isErrno || (errno != syscall.EINVAL && errno != syscall.ENOTTY) {
|
||
|
|
return -1, -1, fmt.Errorf("error getting PTY descriptor: %v", err)
|
||
|
|
}
|
||
|
|
// EINVAL means the kernel's too old to understand TIOCGPTPEER. Try TIOCGPTN.
|
||
|
|
ptyN, err := unix.IoctlGetInt(controlFd, unix.TIOCGPTN)
|
||
|
|
if err != nil {
|
||
|
|
return -1, -1, fmt.Errorf("error getting PTY number: %v", err)
|
||
|
|
}
|
||
|
|
ptyName := fmt.Sprintf("/dev/pts/%d", ptyN)
|
||
|
|
fd, err := unix.Open(ptyName, unix.O_RDWR|unix.O_NOCTTY, 0620)
|
||
|
|
if err != nil {
|
||
|
|
return -1, -1, fmt.Errorf("error opening PTY %q: %v", ptyName, err)
|
||
|
|
}
|
||
|
|
ptyFd = uintptr(fd)
|
||
|
|
}
|
||
|
|
return controlFd, int(ptyFd), nil
|
||
|
|
}
|