installer: Run commands without hopping through the shell.

* gnu/installer/utils.scm (run-shell-command): Rename to...
(run-command): Remove call to 'call-with-temporary-output-file' and hop
through Bash.  Expect COMMAND to be a list of strings rather than a
string.
* gnu/installer/final.scm (install-system): Turn INSTALL-COMMAND into a
list of strings and pass it to 'run-command'.
* gnu/installer/newt/page.scm (edit-file): Likewise.

gnu/installer/final.scm

@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018, 2020 Mathieu Othacehe <m.othacehe@gmail.com>
-;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -111,10 +111,9 @@ cow-store service."
 Start COW-STORE service on target directory and launch guix install command in
 a subshell.  LOCALE must be the locale name under which that command will run,
 or #f.  Return #t on success and #f on failure."
-  (let ((install-command
-         (format #f "guix system init --fallback ~a ~a"
-                 (%installer-configuration-file)
-                 (%installer-target-dir))))
+  (let ((install-command (list "guix" "system" "init" "--fallback"
+                               (%installer-configuration-file)
+                               (%installer-target-dir))))
     (mkdir-p (%installer-target-dir))
 
     ;; We want to initialize user passwords but we don't want to store them in
@@ -128,7 +127,7 @@ or #f.  Return #t on success and #f on failure."
       (lambda ()
         (start-service 'cow-store (list (%installer-target-dir))))
       (lambda ()
-        (run-shell-command install-command #:locale locale))
+        (run-command install-command #:locale locale))
       (lambda ()
         (stop-service 'cow-store)
         ;; Remove the store overlay created at cow-store service start.

gnu/installer/newt/page.scm

@@ -719,9 +719,8 @@ ITEMS when 'Ok' is pressed."
   (newt-suspend)
   ;; Use Nano because it syntax-highlights Scheme by default.
   ;; TODO: Add a menu to choose an editor?
-  (run-shell-command (string-append "/run/current-system/profile/bin/nano "
-                                    file)
-                     #:locale locale)
+  (run-command (list "/run/current-system/profile/bin/nano" file)
+               #:locale locale)
   (newt-resume))
 
 (define* (run-file-textbox-page #:key

gnu/installer/utils.scm

@@ -32,7 +32,7 @@
             read-all
             nearest-exact-integer
             read-percentage
-            run-shell-command
+            run-command
 
             syslog-port
             syslog
@@ -68,48 +68,48 @@ number. If no percentage is found, return #f"
     (and result
          (string->number (match:substring result 1)))))
 
-(define* (run-shell-command command #:key locale)
-  "Run COMMAND, a string, with Bash, and in the given LOCALE.  Return true if
+(define* (run-command command #:key locale)
+  "Run COMMAND, a list of strings, in the given LOCALE.  Return true if
 COMMAND exited successfully, #f otherwise."
+  (define env (environ))
+
   (define (pause)
     (format #t (G_ "Press Enter to continue.~%"))
     (send-to-clients '(pause))
+    (environ env)                               ;restore environment variables
     (match (select (cons (current-input-port) (current-clients))
              '() '())
       (((port _ ...) _ _)
        (read-line port))))
 
-  (call-with-temporary-output-file
-   (lambda (file port)
-     (when locale
-       (let ((supported? (false-if-exception
-                          (setlocale LC_ALL locale))))
-         ;; If LOCALE is not supported, then set LANGUAGE, which might at
-         ;; least give us translated messages.
-         (if supported?
-             (format port "export LC_ALL=\"~a\"~%" locale)
-             (format port "export LANGUAGE=\"~a\"~%"
-                     (string-take locale
-                                  (string-index locale #\_))))))
+  (setenv "PATH" "/run/current-system/profile/bin")
 
-     (format port "exec ~a~%" command)
-     (close port)
+  (when locale
+    (let ((supported? (false-if-exception
+                       (setlocale LC_ALL locale))))
+      ;; If LOCALE is not supported, then set LANGUAGE, which might at
+      ;; least give us translated messages.
+      (if supported?
+          (setenv "LC_ALL" locale)
+          (setenv "LANGUAGE"
+                  (string-take locale
+                               (string-index locale #\_))))))
 
-     (guard (c ((invoke-error? c)
-                (newline)
-                (format (current-error-port)
-                        (G_ "Command failed with exit code ~a.~%")
-                        (invoke-error-exit-status c))
-                (syslog "command ~s failed with exit code ~a"
-                        command (invoke-error-exit-status c))
-                (pause)
-                #f))
-       (syslog "running command ~s~%" command)
-       (invoke "bash" "--init-file" file)
-       (syslog "command ~s succeeded~%" command)
-       (newline)
-       (pause)
-       #t))))
+  (guard (c ((invoke-error? c)
+             (newline)
+             (format (current-error-port)
+                     (G_ "Command failed with exit code ~a.~%")
+                     (invoke-error-exit-status c))
+             (syslog "command ~s failed with exit code ~a"
+                     command (invoke-error-exit-status c))
+             (pause)
+             #f))
+    (syslog "running command ~s~%" command)
+    (apply invoke command)
+    (syslog "command ~s succeeded~%" command)
+    (newline)
+    (pause)
+    #t))
 
 
 ;;;