Refactor bin/doom

So innocuous CLI command return values don't break the post-script
written to /tmp/doom.sh.

bin/doom

@@ -23,6 +23,54 @@
         (expand-file-name
          "../" (file-name-directory (file-truename load-file-name)))))
 
+
+;;
+;;; Sanity checks
+
+(when (version< emacs-version "26.3")
+  (error
+   (concat "Detected Emacs " emacs-version " (at " (car command-line-args) ").\n\n"
+           "Doom only supports Emacs 26.3 and newer. 27.1 is highly recommended. A guide\n"
+           "to install a newer version of Emacs can be found at:\n\n  "
+           (format "https://doomemacs.org/docs/getting_started.org#%s"
+                   (cond ((eq system-type 'darwin) "on-macos")
+                         ((memq system-type '(cygwin windows-nt ms-dos)) "on-windows")
+                         ("on-linux")))
+           "Aborting...")))
+
+(unless (file-readable-p (expand-file-name "core/core.el" user-emacs-directory))
+  (error
+   (concat
+    "Couldn't find or read '"
+    (abbreviate-file-name
+     (expand-file-name "core/core.el" user-emacs-directory))
+    "'.\n\n"
+    "Are you sure Doom Emacs is correctly installed?\n\n"
+    (when (file-symlink-p load-file-name)
+      (concat "This error can occur if you've symlinked the 'doom' script, which Doom does not\n"
+              "support. Consider symlinking its parent directory instead or explicitly set the\n"
+              "EMACSDIR environment variable, e.g.\n\n  "
+              (if (string-match-p "/fish$" (getenv "SHELL"))
+                  "env EMACSDIR=~/.emacs.d doom"
+                "EMACSDIR=~/.emacs.d doom sync"))
+      "\n\n")
+    "Aborting...")))
+
+(when (equal (user-real-uid) 0)
+  ;; If ~/.emacs.d is owned by root, assume the user genuinely wants root to be
+  ;; their primary user.
+  (unless (= 0 (file-attribute-user-id (file-attributes user-emacs-directory)))
+    (error
+     (concat
+      "Do not run this script as root. It will cause file permissions errors later.\n\n"
+      "To carry on anyway, change the owner of your Emacs config to root:\n\n"
+      "  chown root:root -R " (abbreviate-file-name user-emacs-directory) "\n\n"
+      "Aborting..."))))
+
+
+;;
+;;; Let 'er rip!
+
 ;; HACK Load `cl' and site files manually to prevent polluting logs and stdout
 ;;      with deprecation and/or file load messages.
 (let ((inhibit-message t))
@@ -43,69 +91,48 @@
         (setq tail (cdr tail)))
       (load site-run-file t (not verbose)))))
 
-(kill-emacs
- (pcase
-     (catch 'exit
-       ;; Catch some potential issues early
-       (cond
-        ((version< emacs-version "26.3")
-         (princ (concat "Detected Emacs " emacs-version " (at " (car command-line-args) ").\n\n"))
-         (princ "Doom only supports Emacs 26.3 and newer. 27.1 is highly recommended. A guide\n")
-         (princ "to install a newer version of Emacs can be found at:\n\n  ")
-         (princ (format "https://doomemacs.org/docs/getting_started.org#%s"
-                        (cond ((eq system-type 'darwin) "on-macos")
-                              ((memq system-type '(cygwin windows-nt ms-dos)) "on-windows")
-                              ("on-linux"))))
-         (princ "Aborting...")
-         1)
-
-        ((not (file-readable-p (expand-file-name "core/core.el" user-emacs-directory)))
-         (princ (concat "Couldn't find or read '"
-                        (abbreviate-file-name
-                         (expand-file-name "core/core.el" user-emacs-directory))
-                        "'.\n\n"))
-         (princ "Are you sure Doom Emacs is correctly installed?\n\n")
-         (when (file-symlink-p load-file-name)
-           (princ "This error can occur if you've symlinked the 'doom' script, which Doom does not\n")
-           (princ "support. Consider symlinking its parent directory instead or explicitly set the\n")
-           (princ "EMACSDIR environment variable, e.g.\n\n  ")
-           (princ (if (string-match-p "/fish$" (getenv "SHELL"))
-                      "env EMACSDIR=~/.emacs.d doom"
-                    "EMACSDIR=~/.emacs.d doom sync"))
-           (princ "\n\n")
-           (princ "Aborting..."))
-         2)
-
-        ((and (equal (user-real-uid) 0)
-              (/= 0 (file-attribute-user-id (file-attributes user-emacs-directory))))
-         (princ "Do not run this script as root. It will cause file permissions errors later.\n\n")
-         (princ "To carry on anyway, change the owner of your Emacs config to root:\n\n")
-         (princ (concat "  chown root:root -R " (abbreviate-file-name user-emacs-directory) "\n\n"))
-         (princ "Aborting...")
-         3)
-
 ;; Load the heart of the beast and its CLI processing library
-        ((load (expand-file-name "core/core.el" user-emacs-directory) nil t)
+(load (expand-file-name "core/core.el" user-emacs-directory) nil t)
 (require 'core-cli)
 
-         ;; Process the arguments passed to this script. `doom-cli-execute'
+(kill-emacs
-         ;; should return a boolean, integer (error code) or throw an 'exit
+ ;; Process the arguments passed to this script. `doom-cli-execute' should
-         ;; event, which is handled specially.
+ ;; return one of two things: a cons cell whose CAR is t, and CDR is the
-         (apply #'doom-cli-execute :doom (cdr (member "--" argv))))))
+ ;; command's return value OR one of: a keyword, command string, or command
+ ;; list.
+ (pcase (apply #'doom-cli-execute :doom (cdr (member "--" argv)))
 
-   ;; Any non-zero integer is treated as an explicit exit code.
+   ;; If a CLI command returns an integer, treat it as an exit code.
-   ((and (pred integerp) code)
+   ((and (app car-safe `t) code)
-    code)
+    (if (integerp (cdr code))
+        (cdr code)))
 
-   ;; If, instead, we were given a string or list of strings, copy these as
+   ;; CLI commands can do (throw 'exit SHELL-COMMAND) to run something after
-   ;; shell script commands to a temporary script file which this script will
+   ;; this session ends. e.g.
-   ;; execute after this session finishes. Also accepts special keywords, like
+   ;;
-   ;; `:restart', to rerun the current command with the same arguments.
+   ;;   (throw 'exit "$@") or (throw 'exit :restart)
-   ((and (or (pred consp)
+   ;;     This reruns the current command with the same arguments.
-             (pred stringp)
+   ;;   (throw 'exit "$@ -h -c")
-             (pred keywordp))
+   ;;     This reruns the current command with two new switches.
+   ;;   (throw 'exit "emacs -nw FILE")
+   ;;     Opens Emacs on FILE
+   ;;   (throw 'exit t) or (throw 'exit nil)
+   ;;     A safe way to simply abort back to the shell with exit code 0
+   ;;   (throw 'exit 42)
+   ;;     Abort to shell with an explicit exit code (as a more abrupt
+   ;;     alternative to having the CLI command return 42).
+   ;;
+   ;; How this works: the command is written to a temporary shell script which
+   ;; is executed after this session ends (see the shebang lines of this file).
+   ;; It's done this way because Emacs' batch library lacks an implementation of
+   ;; the exec system call.
+   (command
+    (cond
+     ((integerp command)
       command)
-    (let ((script (expand-file-name "doom.sh" temporary-file-directory))
+     ((booleanp command)
+      0)
+     ((let ((script (expand-file-name "doom.sh" temporary-file-directory))
             (coding-system-for-write 'utf-8-unix)
             (coding-system-for-read  'utf-8-unix))
         (with-temp-file script
@@ -132,11 +159,9 @@
                                             (shell-quote-argument (match-string 2 env)))))
                   (format "PATH=\"%s%s$PATH\" \\\n" (concat doom-emacs-dir "bin/") path-separator)
                   "_postscript $@\n"))
-      (set-file-modes script #o600))
+        (set-file-modes script #o600))))
+
       ;; Error code 128 is special: it means run the post-script after this
       ;; session ends.
       128)
-
+   ))
-   ;; Anything else (e.g. booleans) is treated as a successful run. Yes, a `nil'
-   ;; indicates a successful run too!
-   (_ 0)))

core/autoload/output.el

@@ -108,7 +108,7 @@ Accepts 'ansi and 'text-properties. nil means don't render colors.")
   (unless (string-empty-p output)
     (princ output)
     (terpri)
-    t))
+    output))
 
 ;;;###autoload
 (defun doom--output-indent (width text &optional prefix)

core/core-cli.el

@@ -127,11 +127,12 @@ Environment variables:
             (when command
               (push command args))
             (setq command "help"))
-          (if (null command)
+          (cons
+           t (if (null command)
                  (doom-cli-execute "help")
                (let ((start-time (current-time)))
                  (run-hooks 'doom-cli-pre-hook)
-              (when (apply #'doom-cli-execute command args)
+                 (when-let (result (apply #'doom-cli-execute command args))
                    (run-hooks 'doom-cli-post-hook)
                    (print! (success "Finished in %s")
                            (let* ((duration (float-time (time-subtract (current-time) before-init-time)))
@@ -143,7 +144,8 @@ Environment variables:
                                nil (list (unless (zerop hours)   (format "%dh" hours))
                                          (unless (zerop minutes) (format "%dm" minutes))
                                          (format (if (> duration 60) "%ds" "%.4fs")
-                                              seconds)))))))))))
+                                                 seconds))))))
+                   result))))))
     ;; TODO Not implemented yet
     (doom-cli-command-not-found-error
      (print! (error "Command 'doom %s' not recognized") (string-join (cdr e) " "))