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package pty
/* based on:
http://src.illumos.org/source/xref/illumos-gate/usr/src/lib/libc/port/gen/pt.c
*/
import (
"errors"
"golang.org/x/sys/unix"
"os"
"strconv"
"syscall"
"unsafe"
)
const NODEV = ^uint64(0)
func open() (pty, tty *os.File, err error) {
masterfd, err := syscall.Open("/dev/ptmx", syscall.O_RDWR|unix.O_NOCTTY, 0)
//masterfd, err := syscall.Open("/dev/ptmx", syscall.O_RDWR|syscall.O_CLOEXEC|unix.O_NOCTTY, 0)
if err != nil {
return nil, nil, err
}
p := os.NewFile(uintptr(masterfd), "/dev/ptmx")
sname, err := ptsname(p)
if err != nil {
return nil, nil, err
}
err = grantpt(p)
if err != nil {
return nil, nil, err
}
err = unlockpt(p)
if err != nil {
return nil, nil, err
}
slavefd, err := syscall.Open(sname, os.O_RDWR|unix.O_NOCTTY, 0)
if err != nil {
return nil, nil, err
}
t := os.NewFile(uintptr(slavefd), sname)
// pushing terminal driver STREAMS modules as per pts(7)
for _, mod := range([]string{"ptem", "ldterm", "ttcompat"}) {
err = streams_push(t, mod)
if err != nil {
return nil, nil, err
}
}
return p, t, nil
}
func minor(x uint64) uint64 {
return x & 0377
}
func ptsdev(fd uintptr) uint64 {
istr := strioctl{ISPTM, 0, 0, nil}
err := ioctl(fd, I_STR, uintptr(unsafe.Pointer(&istr)))
if err != nil {
return NODEV
}
var status unix.Stat_t
err = unix.Fstat(int(fd), &status)
if err != nil {
return NODEV
}
return uint64(minor(status.Rdev))
}
func ptsname(f *os.File) (string, error) {
dev := ptsdev(f.Fd())
if dev == NODEV {
return "", errors.New("not a master pty")
}
fn := "/dev/pts/" + strconv.FormatInt(int64(dev), 10)
// access(2) creates the slave device (if the pty exists)
// F_OK == 0 (unistd.h)
err := unix.Access(fn, 0)
if err != nil {
return "", err
}
return fn, nil
}
type pt_own struct {
pto_ruid int32
pto_rgid int32
}
func grantpt(f *os.File) error {
if ptsdev(f.Fd()) == NODEV {
return errors.New("not a master pty")
}
var pto pt_own
pto.pto_ruid = int32(os.Getuid())
// XXX should first attempt to get gid of DEFAULT_TTY_GROUP="tty"
pto.pto_rgid = int32(os.Getgid())
var istr strioctl
istr.ic_cmd = OWNERPT
istr.ic_timout = 0
istr.ic_len = int32(unsafe.Sizeof(istr))
istr.ic_dp = unsafe.Pointer(&pto)
err := ioctl(f.Fd(), I_STR, uintptr(unsafe.Pointer(&istr)))
if err != nil {
return errors.New("access denied")
}
return nil
}
func unlockpt(f *os.File) error {
istr := strioctl{UNLKPT, 0, 0, nil}
return ioctl(f.Fd(), I_STR, uintptr(unsafe.Pointer(&istr)))
}
// push STREAMS modules if not already done so
func streams_push(f *os.File, mod string) error {
var err error
buf := []byte(mod)
// XXX I_FIND is not returning an error when the module
// is already pushed even though truss reports a return
// value of 1. A bug in the Go Solaris syscall interface?
// XXX without this we are at risk of the issue
// https://www.illumos.org/issues/9042
// but since we are not using libc or XPG4.2, we should not be
// double-pushing modules
err = ioctl(f.Fd(), I_FIND, uintptr(unsafe.Pointer(&buf[0])))
if err != nil {
return nil
}
err = ioctl(f.Fd(), I_PUSH, uintptr(unsafe.Pointer(&buf[0])))
return err
}
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