[PATCH v2 2/2] systemd-logind: Only use systemd-logind integration together with keeptty

[Aaron Plattner]

On 04/30/2015 05:24 AM, Hans de Goede wrote:
> systemd-logind integration does not work when starting X on a new tty, as
> that detaches X from the current session and after hat systemd-logind revokes
> all rights any already open fds and refuses to open new fds for X.
>
> This means that currently e.g. "startx -- vt7" breaks, and breaks badly,
> requiring ssh access to the system to kill X.
>
> The fix for this is easy, we must not use systemd-logind integration when
> not using KeepTty, or iow we may only use systemd-logind integration together
> with KeepTty.
>
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>

I can confirm that this fixes VT switching for X servers started from an 
SSH session on Arch Linux, which I use all the time for debugging. So

Tested-by: Aaron Plattner <aplattner at nvidia.com>

I was afraid not using -keeptty was going to break using a debugger, but 
it looks like it works these days. Not using -keeptty breaks ctrl-Z to 
suspend the server, but I'm less concerned about that.

> ---
> Changes in v2:
> -Document that -keeptty must be passed for logind integration in man page
> -Print an INFO message when disabling logind integration due to -keeptty
>   not being set
> ---
>   hw/xfree86/man/Xorg.man                      | 6 +++---
>   hw/xfree86/os-support/linux/systemd-logind.c | 9 +++++++++
>   2 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/hw/xfree86/man/Xorg.man b/hw/xfree86/man/Xorg.man
> index 3ff6aef..0864a58 100644
> --- a/hw/xfree86/man/Xorg.man
> +++ b/hw/xfree86/man/Xorg.man
> @@ -271,9 +271,9 @@ is ignored if
>   is anything other than \(oqPCI\(cq.
>   .TP 8
>   .B \-keeptty
> -Prevent the server from detaching its initial controlling terminal.
> -This option is only useful when debugging the server.  Not all platforms
> -support (or can use) this option.
> +Prevent the server from detaching its initial controlling terminal. If you
> +want to use systemd-logind integration you must specify this option.
> +Not all platorms support (or can use) this option.
>   .TP 8
>   .BI \-keyboard " keyboard-name"
>   Use the xorg.conf(__filemansuffix__) file
> diff --git a/hw/xfree86/os-support/linux/systemd-logind.c b/hw/xfree86/os-support/linux/systemd-logind.c
> index 4ad41a3..72f1ae3 100644
> --- a/hw/xfree86/os-support/linux/systemd-logind.c
> +++ b/hw/xfree86/os-support/linux/systemd-logind.c
> @@ -34,6 +34,7 @@
>
>   #include "os.h"
>   #include "dbus-core.h"
> +#include "linux.h"
>   #include "xf86.h"
>   #include "xf86platformBus.h"
>   #include "xf86Xinput.h"
> @@ -596,6 +597,14 @@ static struct dbus_core_hook core_hook = {
>   int
>   systemd_logind_init(void)
>   {
> +    linux_parse_vt_settings();
> +    if (!linux_get_keeptty()) {
> +        LogMessage(X_INFO,
> +            "systemd-logind: logind integration requires -keeptty and "
> +            "-keeptty was not provided, disabling logind integration\n");
> +        return 1;
> +    }
> +
>       return dbus_core_add_hook(&core_hook);
>   }
>
>