[bug#49969] [PATCH v3 06/10] gnu: desktop: Add greetd-service-type

[muradm]

Currently, only agreety configuration is provided.

* gnu/services/desktop.scm: Add greetd-service-type
---
 gnu/services/desktop.scm | 225 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 225 insertions(+)

diff --git a/gnu/services/desktop.scm b/gnu/services/desktop.scm
index a63a2936a7..b7ac08cf20 100644
--- a/gnu/services/desktop.scm
+++ b/gnu/services/desktop.scm
@@ -49,6 +49,7 @@
   #:use-module (gnu system pam)
   #:use-module (gnu packages glib)
   #:use-module (gnu packages admin)
+  #:use-module (gnu packages bash)
   #:use-module (gnu packages cups)
   #:use-module (gnu packages freedesktop)
   #:use-module (gnu packages gnome)
@@ -160,6 +161,12 @@
             seatd-configuration
             seatd-service-type
 
+            greetd-configuration
+            greetd-terminal-configuration
+            greetd-service-type
+            greetd-agreety-tty-session
+            greetd-agreety-tty-xdg-session
+
             %desktop-services))
 
 ;;; Commentary:
@@ -1240,6 +1247,224 @@ applications needing access to be root.")
      (service-extension shepherd-root-service-type seatd-shepherd-service)))
    (default-value (seatd-configuration))))
 
+
+;;;
+;;; greetd-service-type -- minimal and flexible login manager daemon
+;;;
+
+(define-record-type* <greetd-agreety-session>
+  greetd-agreety-session make-greetd-agreety-session
+  greetd-agreety-session?
+  (package greetd-agreety-command-package (default bash))
+  (command-bin greetd-agreety-command-bin (default "/bin/bash"))
+  (command-args greetd-agreety-command-args (default '("-l")))
+  (extra-env greetd-agreety-extra-env (default '()))
+  (command-generator greetd-agreety-command-generator))
+
+(define greetd-agreety-tty-session-command
+  (match-lambda
+    (($ <greetd-agreety-session> pkg command-bin command-args extra-env)
+     (program-file
+      "agreety-tty-session-command"
+      #~(begin
+          (use-modules (ice-9 match))
+          (let* ((abs-cmd-bin #$(file-append pkg command-bin)))
+            (for-each
+             (match-lambda ((var . val) (setenv var val)))
+             (quote (#$@extra-env)))
+            (apply execl abs-cmd-bin abs-cmd-bin
+                   (list #$@command-args))))))))
+
+(define greetd-agreety-tty-xdg-session-command
+  (match-lambda
+    (($ <greetd-agreety-session> package command-bin command-args extra-env)
+     (program-file
+      "agreety-tty-xdg-session-command"
+      #~(begin
+          (use-modules (ice-9 match))
+          (let*
+              ((username (getenv "USER"))
+               (useruid (passwd:uid (getpwuid username)))
+               (useruid (number->string useruid))
+               (abs-cmd-bin #$(file-append package command-bin)))
+            (setenv "XDG_SESSION_TYPE" "tty")
+            (setenv "XDG_RUNTIME_DIR" (string-append "/run/user/" useruid))
+            (for-each
+             (match-lambda ((var . val) (setenv var val)))
+             (quote (#$@extra-env)))
+            (apply execl abs-cmd-bin abs-cmd-bin
+                   (list #$@command-args))))))))
+
+(define greetd-agreety-tty-session
+  (greetd-agreety-session
+   (command-generator greetd-agreety-tty-session-command)))
+
+(define greetd-agreety-tty-xdg-session
+  (greetd-agreety-session
+   (command-generator greetd-agreety-tty-xdg-session-command)))
+
+(define-record-type* <greetd-terminal-configuration>
+  greetd-terminal-configuration make-greetd-terminal-configuration
+  greetd-terminal-configuration?
+  (greetd greetd-package (default greetd))
+  (config-file-name greetd-config-file-name (thunked)
+                    (default (default-config-file-name this-record)))
+  (terminal-vt greetd-terminal-vt (default "7"))
+  (default-session-user greetd-default-session-user (default "greeter"))
+  (default-session-command greetd-default-session-command
+    (default greetd-agreety-tty-xdg-session)))
+
+(define (default-config-file-name config)
+  (string-join (list "config-" (greetd-terminal-vt config) ".toml") ""))
+
+(define make-greetd-terminal-default-session-command
+  (match-lambda
+    (($ <greetd-terminal-configuration> greetd _ _ _ default-session-command)
+     (cond ((greetd-agreety-session? default-session-command)
+            (let*
+                ((generator (greetd-agreety-command-generator
+                             default-session-command))
+                 (command (apply generator (list default-session-command)))
+                 (agreety-bin (file-append greetd "/bin/agreety")))
+              (program-file
+               "agreety-command"
+               #~(execl #$agreety-bin #$agreety-bin "-c" #$command))))
+           (else (program-file "agreety-command-exit" #~(exit #f)))))))
+
+(define (make-greetd-terminal-configuration-file config)
+  (let*
+      ((config-file-name (greetd-config-file-name config))
+       (terminal-vt (greetd-terminal-vt config))
+       (default-session-user (greetd-default-session-user config))
+       (default-session-command (make-greetd-terminal-default-session-command 
config)))
+    (mixed-text-file
+     config-file-name
+     "[terminal]\n"
+     "vt = " terminal-vt "\n"
+     "[default_session]\n"
+     "user = " default-session-user "\n"
+     "command = " default-session-command "\n")))
+
+(define %default-motd
+  (plain-file "motd" "This is the GNU operating system, welcome!\n\n"))
+
+(define %greetd-accounts
+  (list (user-account
+         (name "greeter")
+         (group "wheel")
+         (supplementary-groups '("users" "tty" "input" "video" "audio"))
+         (system? #t))))
+
+(define %greetd-file-systems
+  (list (file-system
+          (device "none")
+          (mount-point "/run/greetd/pam_mount")
+          (type "tmpfs")
+          (check? #f)
+          (flags '(no-suid no-dev no-exec))
+          (options "mode=0755")
+          (create-mount-point? #t))))
+
+(define %greetd-pam-mount-rules
+  `((debug (@ (enable "0")))
+    (volume (@ (sgrp "users")
+               (fstype "tmpfs")
+               (mountpoint "/run/user/%(USERUID)")
+               (options 
"noexec,nosuid,nodev,size=1g,mode=0700,uid=%(USERUID),gid=%(USERGID)")))
+    (logout (@ (wait "0")
+               (hup "0")
+               (term "yes")
+               (kill "no")))
+    (mkmountpoint (@ (enable "1") (remove "true")))))
+
+(define-record-type* <greetd-configuration>
+  greetd-configuration make-greetd-configuration
+  greetd-configuration?
+  (motd greetd-motd (default %default-motd))
+  (allow-empty-passwords? greetd-allow-empty-passwords? (default #t))
+  (terminals greetd-terminals (default '())))
+
+(define (make-greetd-pam-mount-conf-file config)
+  (computed-file
+   "greetd_pam_mount.conf.xml"
+   #~(begin
+       (use-modules (sxml simple))
+       (call-with-output-file #$output
+         (lambda (port)
+           (sxml->xml
+            '(*TOP*
+              (*PI* xml "version='1.0' encoding='utf-8'")
+              (pam_mount
+               #$@%greetd-pam-mount-rules
+               (pmvarrun
+                #$(file-append greetd-pam-mount
+                               "/sbin/pmvarrun -u '%(USER)' -o 
'%(OPERATION)'"))))
+            port))))))
+
+(define (greetd-etc-service config)
+  `(("security/greetd_pam_mount.conf.xml"
+     ,(make-greetd-pam-mount-conf-file config))))
+
+(define (greetd-pam-service config)
+  (define optional-pam-mount
+    (pam-entry
+     (control "optional")
+     (module #~(string-append #$greetd-pam-mount 
"/lib/security/pam_mount.so"))))
+
+  (list
+   (unix-pam-service "greetd"
+                     #:login-uid? #t
+                     #:allow-empty-passwords?
+                     (greetd-allow-empty-passwords? config)
+                     #:motd
+                     (greetd-motd config))
+   (lambda (pam)
+     (if (member (pam-service-name pam)
+                 '("login" "greetd" "su" "slim" "gdm-password"))
+         (pam-service
+          (inherit pam)
+          (auth (append (pam-service-auth pam)
+                        (list optional-pam-mount)))
+          (session (append (pam-service-session pam)
+                           (list optional-pam-mount))))
+         pam))))
+
+(define (greetd-shepherd-services config)
+  (map
+   (lambda (tc)
+     (let*
+         ((greetd-bin (file-append (greetd-package tc) "/sbin/greetd"))
+          (greetd-conf (make-greetd-terminal-configuration-file tc))
+          (greetd-vt (greetd-terminal-vt tc)))
+       (shepherd-service
+        (documentation "Minimal and flexible login manager daemon")
+        (requirement '(user-processes host-name udev virtual-terminal))
+        (provision (list (symbol-append
+                          'term-tty
+                          (string->symbol (greetd-terminal-vt tc)))))
+        (start #~(make-forkexec-constructor
+                  (list #$greetd-bin "-c" #$greetd-conf)
+                  #:log-file
+                  (string-append "/tmp/greetd." #$greetd-vt ".log")))
+        (stop #~(make-kill-destructor)))))
+   (greetd-terminals config)))
+
+(define greetd-service-type
+  (service-type
+   (name 'greetd)
+   (description "Provides necessary infrastructure for logging into the
+system including @code{greetd} PAM service, @code{pam-mount} module to
+mount/unmount /run/user/<uid> directory for user and @code{greetd}
+login manager daemon.")
+   (extensions
+    (list
+     (service-extension account-service-type (const %greetd-accounts))
+     (service-extension file-system-service-type (const %greetd-file-systems))
+     (service-extension etc-service-type greetd-etc-service)
+     (service-extension pam-root-service-type greetd-pam-service)
+     (service-extension shepherd-root-service-type greetd-shepherd-services)))
+   (default-value (greetd-configuration))))
+
 
 ;;;
 ;;; The default set of desktop services.
-- 
2.32.0