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