Merge branch 'autoterminal' into 'main'

implement autoterminal: automatically started scripts that take over a virtual terminal for user interaction

See merge request systemrescue/systemrescue-sources!196

airootfs/etc/systemd/scripts/sysrescue-initialize.py

@@ -8,6 +8,29 @@ import glob
 import os
 import sys
 import re
+import tempfile
+
+# pythons os.symlink bails when a file already exists, this function also handles overwrites
+def symlink_overwrite(target, link_file):
+    link_dir = os.path.dirname(link_file)
+    
+    while True:
+        # get a tmp filename in the same dir as link_file
+        tmp = tempfile.NamedTemporaryFile(delete=True, dir=link_dir)
+        tmp.close()
+        # tmp is now deleted
+        
+        # os.symlink aborts when a file with the same name already exists
+        # someone could have created a new file with the tmp name right in this moment
+        # so we need to loop and try again in this case
+        try:
+            os.symlink(target,tmp.name)
+            break
+        except FileExistsError:
+            pass
+    
+    os.replace(tmp.name, link_file)
+
 
 # ==============================================================================
 # Initialization
@@ -179,6 +202,64 @@ if (late_load_srm != None) and (late_load_srm != ""):
     # so we have to do this manually. Note: only affects multi-user.target, nothing else
     subprocess.run(["/usr/bin/systemctl", "--no-block", "start", "multi-user.target"])
 
+# ==============================================================================
+# autoterminal: programs that take over a virtual terminal for user interaction
+# ==============================================================================
+
+# expect a dict with terminal-name: command, like config['autoterminal']['tty2'] = "/usr/bin/setkmap"
+if ('autoterminal' in config) and (config['autoterminal'] is not None) and \
+   (config['autoterminal'] is not False) and isinstance(config['autoterminal'], dict):
+    print("====> Configuring autoterminal ...")
+    with open('/usr/share/sysrescue/template/autoterminal.service', 'r') as template_file:
+        conf_template = template_file.read()
+    with open('/usr/share/sysrescue/template/serial-autoterminal.service', 'r') as template_file:
+        serial_conf_template = template_file.read()
+    start_services = []
+    for terminal, command in sorted(config['autoterminal'].items()):
+        if m := re.match(r"^serial:([a-zA-Z0-9_-]+)$", terminal):
+            serial=True
+            terminal = m.group(1)
+        else:
+            serial=False
+
+        if not re.match(r"^[a-zA-Z0-9_-]+$", terminal):
+            print (f"Ignoring invalid terminal name '{terminal}'")
+            errcnt+=1
+            continue
+        # do not check if terminal or command exists: an autorun could create them later on
+        if serial:
+            print (f"setting serial terminal '{terminal}' to '{command}'")
+        else:
+            print (f"setting terminal '{terminal}' to '{command}'")
+        with open(f"/etc/systemd/system/autoterminal-{terminal}.service", "w") as terminal_conf:
+            # write service config, based on the template config we loaded above
+            # don't use getty@{terminal}.service name to not use autovt@{terminal}.service on-demand logic
+            if serial:
+                conf_data=serial_conf_template.replace("%TTY%",terminal)
+            else:
+                conf_data=conf_template.replace("%TTY%",terminal)
+
+            conf_data=conf_data.replace("%EXEC%",command)
+            terminal_conf.write(conf_data)
+        # enable service: always start it, do not wait for the user to switch to the terminal
+        # means other programs (like X.org) can't allocate it away, also allows for longer running init sequences
+        symlink_overwrite(f"/etc/systemd/system/autoterminal-{terminal}.service",
+                        f"/etc/systemd/system/getty.target.wants/autoterminal-{terminal}.service")
+
+        # mask the regular getty for this terminal
+        if serial:
+            symlink_overwrite("/dev/null",f"/etc/systemd/system/serial-getty@{terminal}.service")
+        else:
+            symlink_overwrite("/dev/null",f"/etc/systemd/system/getty@{terminal}.service")
+            symlink_overwrite("/dev/null",f"/etc/systemd/system/autovt@{terminal}.service")
+
+        start_services.append(f"autoterminal-{terminal}.service")
+    # reload systemd to allow the new config to take effect
+    subprocess.run(["/usr/bin/systemctl", "daemon-reload"])
+    # explicitly start new services (after daemon-reload): systemd can't update dependencies while starting
+    for s in start_services:
+        subprocess.run(["/usr/bin/systemctl", "--no-block", "start", s])
+
 # ==============================================================================
 # End of the script
 # ==============================================================================

airootfs/usr/share/sysrescue/template/autoterminal.service

@@ -0,0 +1,60 @@
+#  SPDX-License-Identifier: LGPL-2.1-or-later
+#
+#  This file is part of SystemRescue, based on getty@.service from systemd
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=SystemRescue autoterminal %TTY%
+Documentation=https://www.system-rescue.org/manual/autoterminal/
+After=systemd-user-sessions.service plymouth-quit-wait.service getty-pre.target \
+      getty@%TTY%.service autovt@%TTY%.service
+
+# If additional gettys are spawned during boot then we should make
+# sure that this is synchronized before getty.target, even though
+# getty.target didn't actually pull it in.
+Before=getty.target
+IgnoreOnIsolate=yes
+
+# IgnoreOnIsolate causes issues with sulogin, if someone isolates
+# rescue.target or starts rescue.service from multi-user.target or
+# graphical.target.
+Conflicts=rescue.service getty@%TTY%.service autovt@%TTY%.service
+Before=rescue.service
+
+[Service]
+# the VT is cleared by TTYVTDisallocate
+ExecStart=-%EXEC%
+
+# do not wait 5 seconds as for Type=idle before starting the service
+Type=simple
+
+Restart=always
+RestartSec=1
+UtmpIdentifier=%TTY%
+StandardInput=tty
+StandardOutput=tty
+TTYPath=/dev/%TTY%
+TTYReset=yes
+TTYVHangup=yes
+TTYVTDisallocate=yes
+IgnoreSIGPIPE=no
+SendSIGHUP=yes
+
+# make this a systemd-logind session without needing a getty
+User=root
+PAMName=login
+
+# generate all utmp/wtmp entries and don't expect the program to do it
+UtmpMode=user
+
+# Unset locale for the console getty since the console has problems
+# displaying some internationalized messages.
+UnsetEnvironment=LANG LANGUAGE LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY \
+     LC_MESSAGES LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT LC_IDENTIFICATION
+
+[Install]
+WantedBy=getty.target

airootfs/usr/share/sysrescue/template/serial-autoterminal.service

@@ -0,0 +1,54 @@
+#  SPDX-License-Identifier: LGPL-2.1-or-later
+#
+#  This file is part of SystemRescue, based on serial-getty@.service from systemd
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=SystemRescue serial autoterminal %TTY%
+Documentation=https://www.system-rescue.org/manual/autoterminal/
+BindsTo=dev-%TTY%.device
+After=dev-%TTY%.device systemd-user-sessions.service plymouth-quit-wait.service \
+      getty-pre.target serial-getty@%TTY%.service
+
+# If additional gettys are spawned during boot then we should make
+# sure that this is synchronized before getty.target, even though
+# getty.target didn't actually pull it in.
+Before=getty.target
+IgnoreOnIsolate=yes
+
+# IgnoreOnIsolate causes issues with sulogin, if someone isolates
+# rescue.target or starts rescue.service from multi-user.target or
+# graphical.target.
+Conflicts=rescue.service serial-getty@%TTY%.service
+Before=rescue.service
+
+[Service]
+ExecStart=-%EXEC%
+
+# do not wait 5 seconds as for Type=idle before starting the service
+Type=simple
+
+Restart=always
+RestartSec=1
+UtmpIdentifier=%TTY%
+StandardInput=tty
+StandardOutput=tty
+TTYPath=/dev/%TTY%
+TTYReset=yes
+TTYVHangup=yes
+IgnoreSIGPIPE=no
+SendSIGHUP=yes
+
+# make this a systemd-logind session without needing a getty
+User=root
+PAMName=login
+
+# generate all utmp/wtmp entries and don't expect the program to do it
+UtmpMode=user
+
+[Install]
+WantedBy=getty.target