master 65108998b1e: docview: imenu: check return value of 'mutool'

[Eli Zaretskii]

branch: master
commit 65108998b1ee0b42b57d478ba3b51f9040f04cd4
Author: Morgan Smith <Morgan.J.Smith@outlook.com>
Commit: Eli Zaretskii <eliz@gnu.org>

    docview: imenu: check return value of 'mutool'
    
    While 'mutool' supports many filetypes, 'mutool show' only
    supports PDF files.  This would lead to cryptic imenu errors
    when opening other
    file types (like EPUB) since we would parse the error output.
    During my testing this caused 'imenu--index-alist' to have a
    value of '(nil).
    
    * lisp/doc-view.el (doc-view--pdf-outline): Error when 'mutool'
    returns an error.  Use 'call-process' to get the return value and
    remove the call to 'shell-quote-argument' as 'call-process'
    doesn't want any escapes.
    (doc-view-mode): Handle possible error from 'doc-view-imenu-setup'.
    (doc-view-imenu-enabled): Remove superfluous (and ... t).
    (doc-view-imenu-setup): Remove check for mutool already ensured by
    'doc-view-imenu-enabled' being non-nil.
    (Bug#64516)
---
 lisp/doc-view.el | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/lisp/doc-view.el b/lisp/doc-view.el
index b14655fb274..847601872f5 100644
--- a/lisp/doc-view.el
+++ b/lisp/doc-view.el
@@ -147,6 +147,8 @@
 (require 'filenotify)
 (eval-when-compile (require 'subr-x))
 
+(autoload 'imenu-unavailable-error "imenu")
+
 ;;;; Customization Options
 
 (defgroup doc-view nil
@@ -214,7 +216,7 @@ are available (see Info node `(emacs)Document View')."
   :type 'boolean
   :version "30.1")
 
-(defcustom doc-view-imenu-enabled (and (executable-find "mutool") t)
+(defcustom doc-view-imenu-enabled (executable-find "mutool")
   "Whether to generate an imenu outline when \"mutool\" is available."
   :type 'boolean
   :version "29.1")
@@ -1910,9 +1912,10 @@ structure is extracted by `doc-view--imenu-subtree'."
   (let ((fn (or file-name (buffer-file-name))))
     (when fn
       (let ((outline nil)
-            (fn (shell-quote-argument (expand-file-name fn))))
+            (fn (expand-file-name fn)))
         (with-temp-buffer
-          (insert (shell-command-to-string (format "mutool show %s outline" 
fn)))
+          (unless (= 0 (call-process "mutool" nil (current-buffer) nil "show" 
fn "outline"))
+            (imenu-unavailable-error "Unable to create imenu index using 
`mutool'"))
           (goto-char (point-min))
           (while (re-search-forward doc-view--outline-rx nil t)
             (push `((level . ,(length (match-string 1)))
@@ -1961,7 +1964,7 @@ GOTO-PAGE-FN other than `doc-view-goto-page'."
 
 (defun doc-view-imenu-setup ()
   "Set up local state in the current buffer for imenu, if needed."
-  (when (and doc-view-imenu-enabled (executable-find "mutool"))
+  (when doc-view-imenu-enabled
     (setq-local imenu-create-index-function #'doc-view-imenu-index
                 imenu-submenus-on-top nil
                 imenu-sort-function nil
@@ -2236,7 +2239,10 @@ toggle between displaying the document or editing it as 
text.
     (setq mode-name "DocView"
          buffer-read-only t
          major-mode 'doc-view-mode)
-    (doc-view-imenu-setup)
+    (condition-case imenu-error
+        (doc-view-imenu-setup)
+      (imenu-unavailable (message "imenu support unavailable: %s"
+                                  (cadr imenu-error))))
     (doc-view-initiate-display)
     ;; Switch off view-mode explicitly, because doc-view-mode is the
     ;; canonical view mode for PDF/PS/DVI files.  This could be