bug#70194: SDDM fails to start, black screen on 188d18fc47

[Richard Sent]

Hi Guix!

After upgrading Guix from c9cd16c630 to 188d18fc47, SDDM fails to start
and drops me onto a black screen. I heard from another user on IRC who
seemingly has the same issue, so I think there's a bug here and it's not
a "me" issue.

>From the log, it seems like it might something to do with sddm-helper
communicating with PAM. Normally a line like "[PAM] Conversation with 1
messages" is printed after "[PAM] Authenticating..."

My SDDM configuration:

--8<---------------cut here---------------start------------->8---
(service sddm-service-type
                (sddm-configuration
                 (theme "guix-simplyblack-sddm")
                 (themes-directory (file-append guix-simplyblack-sddm-theme 
"/share/sddm/themes"))))
--8<---------------cut here---------------end--------------->8---

An sddm.log entry when it fails to start:

--8<---------------cut here---------------start------------->8---
[23:28:42.129] (II) DAEMON: Initializing...
[23:28:42.143] (II) DAEMON: Starting...
[23:28:42.144] (II) DAEMON: Logind interface found
[23:28:42.144] (II) DAEMON: Adding new display...
[23:28:42.146] (II) DAEMON: Loaded empty theme configuration
[23:28:42.146] (II) DAEMON: Xauthority path: "/var/run/sddm/xauth_TflZQy"
[23:28:42.147] (II) DAEMON: Using VT 7
[23:28:42.147] (II) DAEMON: Display server starting...
[23:28:42.147] (II) DAEMON: Writing cookie to "/var/run/sddm/xauth_TflZQy"
[23:28:42.147] (II) DAEMON: Running: 
/gnu/store/c6dkx87an4c9qjny6yakxss9zm60wk7p-startx -nolisten tcp -dpi 240 
-background none -seat seat0 vt7 -auth /var/run/sddm/xauth_TflZQy -noreset 
-displayfd 16
[23:28:42.719] (II) DAEMON: Setting default cursor
[23:28:42.728] (WW) DAEMON: Could not setup default cursor
[23:28:42.728] (II) DAEMON: Running display setup script  
"/gnu/store/6ansmr2w8q5kppw4vi5bg9cgmf5h36s8-sddm-0.20.0/share/sddm/scripts/Xsetup"
[23:28:42.732] (II) DAEMON: Display server started.
[23:28:42.732] (II) DAEMON: Socket server starting...
[23:28:42.732] (II) DAEMON: Socket server started.
[23:28:42.735] (II) DAEMON: Loading theme configuration from 
"/gnu/store/vvdgqz68b7hjysyxvx4jgrfs9n8l161a-guix-simplyblack-sddm-theme-0.1/share/sddm/themes/guix-simplyblack-sddm/theme.conf"
[23:28:42.735] (II) DAEMON: Greeter starting...
[23:28:42.746] (II) HELPER: [PAM] Starting...
[23:28:42.746] (II) HELPER: [PAM] Authenticating...
[23:28:42.746] (II) HELPER: [PAM] returning.
[23:28:42.794] (II) HELPER: Writing cookie to "/tmp/xauth_FEgdza"
[23:28:42.794] (II) HELPER: Starting X11 session: "" 
"/gnu/store/6ansmr2w8q5kppw4vi5bg9cgmf5h36s8-sddm-0.20.0/bin/sddm-greeter 
--socket /tmp/sddm-:0-lSqpNm --theme 
/gnu/store/vvdgqz68b7hjysyxvx4jgrfs9n8l161a-guix-simplyblack-sddm-theme-0.1/share/sddm/themes/guix-simplyblack-sddm"
[23:28:42.796] (II) DAEMON: Greeter session started successfully
[23:28:45.920] (II) DAEMON: Message received from greeter: Connect
[23:28:47.626] (II) HELPER: [PAM] Closing session
[23:28:47.628] (II) HELPER: [PAM] Ended.
[23:28:47.639] (WW) DAEMON: Auth: sddm-helper exited with 11
[23:28:47.639] (II) DAEMON: Greeter stopped. SDDM::Auth::HelperExitStatus(11)
--8<---------------cut here---------------end--------------->8---

An sddm.log entry when it successfully runs:

--8<---------------cut here---------------start------------->8---
[23:30:57.842] (II) DAEMON: Initializing...
[23:30:57.846] (II) DAEMON: Starting...
[23:30:57.846] (II) DAEMON: No session manager found
[23:30:57.846] (II) DAEMON: Adding new display...
[23:30:57.847] (II) DAEMON: Loaded empty theme configuration
[23:30:57.848] (II) DAEMON: Xauthority path: "/var/run/sddm/xauth_WsJLVn"
[23:30:57.848] (II) DAEMON: Using VT 7
[23:30:57.848] (II) DAEMON: Display server starting...
[23:30:57.848] (II) DAEMON: Writing cookie to "/var/run/sddm/xauth_WsJLVn"
[23:30:57.848] (II) DAEMON: Running: 
/gnu/store/ybrjbiwpbs440d784p2bmsk7apaybbhy-startx -nolisten tcp -dpi 240 
-background none -seat seat0 vt7 -auth /var/run/sddm/xauth_WsJLVn -noreset 
-displayfd 16
[23:30:58.429] (II) DAEMON: Setting default cursor
[23:30:58.439] (WW) DAEMON: Could not setup default cursor
[23:30:58.439] (II) DAEMON: Running display setup script  
"/gnu/store/n0msvb8vfd3q3f9349kpq8305c4mx67x-sddm-0.20.0/share/sddm/scripts/Xsetup"
[23:30:58.442] (II) DAEMON: Display server started.
[23:30:58.442] (II) DAEMON: Socket server starting...
[23:30:58.442] (II) DAEMON: Socket server started.
[23:30:58.445] (II) DAEMON: Loading theme configuration from 
"/gnu/store/vvdgqz68b7hjysyxvx4jgrfs9n8l161a-guix-simplyblack-sddm-theme-0.1/share/sddm/themes/guix-simplyblack-sddm/theme.conf"
[23:30:58.445] (II) DAEMON: Greeter starting...
[23:30:58.456] (II) HELPER: [PAM] Starting...
[23:30:58.456] (II) HELPER: [PAM] Authenticating...
[23:30:58.456] (II) HELPER: [PAM] returning.
[23:30:58.489] (II) HELPER: Writing cookie to "/tmp/xauth_PUcYpV"
[23:30:58.489] (II) HELPER: Starting X11 session: "" 
"/gnu/store/n0msvb8vfd3q3f9349kpq8305c4mx67x-sddm-0.20.0/bin/sddm-greeter 
--socket /tmp/sddm-:0-cMaMMt --theme 
/gnu/store/vvdgqz68b7hjysyxvx4jgrfs9n8l161a-guix-simplyblack-sddm-theme-0.1/share/sddm/themes/guix-simplyblack-sddm"
[23:30:58.491] (II) DAEMON: Greeter session started successfully
[23:31:01.616] (II) DAEMON: Message received from greeter: Connect
[23:31:05.982] (II) DAEMON: Message received from greeter: Login
[23:31:05.982] (II) DAEMON: Reading from 
"/run/current-system/profile/share/xsessions/stumpwm.desktop"
[23:31:05.982] (II) DAEMON: Session 
"/run/current-system/profile/share/xsessions/stumpwm.desktop" selected, 
command: 
"/gnu/store/fvm9ibhr11bqj09dx5wwha5260hgw2p3-stumpwm-22.11/bin/stumpwm" for VT 7
[23:31:05.991] (II) HELPER: [PAM] Starting...
[23:31:05.991] (II) HELPER: [PAM] Authenticating...
[23:31:05.991] (II) HELPER: [PAM] Preparing to converse...
[23:31:05.991] (II) HELPER: [PAM] Conversation with 1 messages
[23:31:05.996] (II) HELPER: [PAM] returning.
[23:31:05.996] (II) DAEMON: Authentication for user  "richard"  successful
[23:31:06.028] (II) HELPER: Writing cookie to "/tmp/xauth_qHpzQg"
[23:31:06.028] (II) HELPER: Starting X11 session: "" 
"/gnu/store/by9l6s04vi7g7q8nd3ycvaz2p9373y0h-xinitrc 
\"/gnu/store/fvm9ibhr11bqj09dx5wwha5260hgw2p3-stumpwm-22.11/bin/stumpwm\""
[23:31:06.030] (II) DAEMON: Session started true
[23:31:06.044] (II) HELPER: [PAM] Closing session
[23:31:06.045] (II) HELPER: [PAM] Ended.
[23:31:06.047] (II) DAEMON: Auth: sddm-helper exited successfully
[23:31:06.047] (II) DAEMON: Greeter stopped. SDDM::Auth::HELPER_SUCCESS
--8<---------------cut here---------------end--------------->8---

-- 
Take it easy,
Richard Sent
Making my computer weirder one commit at a time.