installer: Add core dump support.

Fixes: <https://issues.guix.gnu.org/58733>

* gnu/installer.scm (installer-program): Enable core dump generation.
* gnu/installer/dump.scm (%core-dump): New variable.
(prepare-dump): Copy the core dump file.
* gnu/installer/newt/welcome.scm (run-welcome-page): Propose to report an
installation that previously generated a core dump.

gnu/installer.scm

@@ -389,6 +389,12 @@ (define installer-builder
                          (ice-9 match)
                          (ice-9 textual-ports))
 
+            ;; Enable core dump generation.
+            (setrlimit 'core #f #f)
+            (call-with-output-file "/proc/sys/kernel/core_pattern"
+              (lambda (port)
+                (format port %core-dump)))
+
             ;; Initialize gettext support so that installers can use
             ;; (guix i18n) module.
             #$init-gettext

gnu/installer/dump.scm

@@ -28,13 +28,17 @@ (define-module (gnu installer dump)
   #:use-module (web http)
   #:use-module (web response)
   #:use-module (webutils multipart)
-  #:export (prepare-dump
+  #:export (%core-dump
+            prepare-dump
             make-dump
             send-dump-report))
 
 ;; The installer crash dump type.
 (define %dump-type "installer-dump")
 
+;; The core dump file.
+(define %core-dump "/tmp/installer-core-dump")
+
 (define (result->list result)
   "Return the alist for the given RESULT."
   (hash-map->list (lambda (k v)
@@ -66,6 +70,10 @@ (define dump-dir
     ;; syslog
     (copy-file "/var/log/messages" "syslog")
 
+    ;; core dump
+    (when (file-exists? %core-dump)
+      (copy-file %core-dump "core-dump"))
+
     ;; dmesg
     (let ((pipe (open-pipe* OPEN_READ "dmesg")))
       (call-with-output-file "dmesg"

gnu/installer/newt/welcome.scm

@@ -20,6 +20,7 @@
 (define-module (gnu installer newt welcome)
   #:use-module ((gnu build linux-modules)
                 #:select (modules-loaded))
+  #:use-module (gnu installer dump)
   #:use-module (gnu installer steps)
   #:use-module (gnu installer utils)
   #:use-module (gnu installer newt page)
@@ -132,6 +133,20 @@ (define (run-welcome-page logo)
 the system does not boot, perhaps you will need to add nomodeset to the
 kernel arguments and need to configure the uvesafb kernel module.")
                       (G_ "Pre-install warning")))
+    (when (file-exists? %core-dump)
+      (match
+          (choice-window
+           (G_ "Previous installation failed")
+           (G_ "Continue")
+           (G_ "Report the failure")
+           (G_ "It seems that the previous installation exited unexpectedly \
+and generated a core dump.  Do you want to continue or to report the failure \
+first?"))
+        (1 #t)
+        (2 (raise
+            (condition
+             (&message
+              (message "User abort.")))))))
     (run-menu-page
      (G_ "GNU Guix install")
      (G_ "Welcome to GNU Guix system installer!