Re: screen-4.6.0 regression: within su: Cannot open your terminal '/dev/pts/14' - please check

On Fri, 30 Jun 2017 15:25:05 +0800
Clark Wang <[email protected]> wrote:

> On Thu, Jun 29, 2017 at 7:31 PM, Andrew Savchenko <[email protected]>
> wrote:
> 
> > Hi,
> >
> > I often use screen within su - username sessions, so that active
> > terminal (e.g. xterm) is owned by a user different from one using
> > su, e.g.:
> >
> > su - test
> > screen
> >
> > This worked fine before 4.6.0 (up to 4.5.1), with 4.6.0 I have:
> >
> > $ su - test
> > $ screen
> > Cannot open your terminal '/dev/pts/14' - please check.
> >
> > /dev/pts/14 is indeed not owned by user test, but this way screen
> > have worked fine for as long as I can remember, so this access
> > should not be mandatory.
> >
> > Any way to return the old behaviour?
> >  
> 
> The following patch (not a real fix) works fine for me. To me it
> looks like the ``#ifndef NAMEDPIPE'' part is wrongly removed from
> v4.5.x code.
> 
> --- src/screen.c        2017-06-30 15:03:24.886002321 +0800
> +++ ../screen-4.6.0/screen.c    2017-06-30 15:12:25.547628467 +0800
> @@ -1001,6 +1001,7 @@
>    attach_tty = "";
>    if (!detached && !lsflag && !cmdflag && !(dflag && !mflag
> && !rflag && !xflag) &&
>        !(sty && !SockMatch && !mflag && !rflag && !xflag)) {
> +      int fl;
> 
>      /* ttyname implies isatty */
>      SetTtyname(true, &st);
> @@ -1008,6 +1009,10 @@
>      tty_mode = (int)st.st_mode & 0777;
>  #endif
> 
> +    fl = fcntl(0, F_GETFL, 0);
> +    if (fl != -1 && (fl & (O_RDWR|O_RDONLY|O_WRONLY)) == O_RDWR)
> +      attach_fd = 0;
> +
>      if (attach_fd == -1) {
>        if ((n = secopen(attach_tty, O_RDWR | O_NONBLOCK, 0)) < 0)
>          Panic(0, "Cannot open your terminal '%s' - please check.",
> attach_tty);

Hey,

indeed that fixes it, thank you for investigating, I will release 4.6.1
soon.

Amadeusz