79 lines
1.5 KiB
Go
79 lines
1.5 KiB
Go
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package pty
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import (
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"errors"
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"os"
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"syscall"
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"unsafe"
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)
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func posixOpenpt(oflag int) (fd int, err error) {
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r0, _, e1 := syscall.Syscall(syscall.SYS_POSIX_OPENPT, uintptr(oflag), 0, 0)
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fd = int(r0)
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if e1 != 0 {
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err = e1
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}
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return fd, err
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}
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func open() (pty, tty *os.File, err error) {
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fd, err := posixOpenpt(syscall.O_RDWR | syscall.O_CLOEXEC)
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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(fd), "/dev/pts")
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// In case of error after this point, make sure we close the pts fd.
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defer func() {
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if err != nil {
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_ = p.Close() // Best effort.
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}
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}()
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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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t, err := os.OpenFile("/dev/"+sname, os.O_RDWR, 0)
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if err != nil {
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return nil, nil, err
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}
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return p, t, nil
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}
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func isptmaster(fd uintptr) (bool, error) {
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err := ioctl(fd, syscall.TIOCPTMASTER, 0)
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return err == nil, err
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}
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var (
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emptyFiodgnameArg fiodgnameArg
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ioctlFIODGNAME = _IOW('f', 120, unsafe.Sizeof(emptyFiodgnameArg))
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)
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func ptsname(f *os.File) (string, error) {
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master, err := isptmaster(f.Fd())
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if err != nil {
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return "", err
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}
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if !master {
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return "", syscall.EINVAL
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}
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const n = _C_SPECNAMELEN + 1
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var (
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buf = make([]byte, n)
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arg = fiodgnameArg{Len: n, Buf: (*byte)(unsafe.Pointer(&buf[0]))}
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)
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if err := ioctl(f.Fd(), ioctlFIODGNAME, uintptr(unsafe.Pointer(&arg))); err != nil {
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return "", err
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}
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for i, c := range buf {
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if c == 0 {
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return string(buf[:i]), nil
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}
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}
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return "", errors.New("FIODGNAME string not NUL-terminated")
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}
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