plugin/emacs: recover from quick-lint-js crashes in Flymake plugin

Signed-off-by: wagner riffel <w@104d.net>

plugin/emacs/flymake-quicklintjs.el

@@ -40,47 +40,89 @@ Return a list of Flymake diagnostic objects in source buffer SRC-BUF."
                                        (if (= sev 0) :error :warning) msg)))
           quicklintjs-output-alist))
 
+(defun flymake-quicklintjs--report-with-crash (qljs-stdout-buf
+                                               qljs-stderr-buf
+                                               src-buf report-fn)
+  "Similar to `flymake-quicklintjs--report' but tries to recover errors from
+quick-lint-js crashes and logs whatever is in QLJS-STDERR-BUF"
+  (flymake-log :warning
+               "quick-lint-js exited with a deadly signal.\n\
+Please consider filing a bug at\
+ https://github.com/quick-lint/quick-lint-js/issues/new\n\
+qjls-stderr-buf:\n\
+%s\n"
+               (with-current-buffer qljs-stderr-buf
+                 (buffer-substring-no-properties (point-min) (point-max))))
+  (with-current-buffer qljs-stdout-buf
+    (save-excursion
+      ;; a crash without any previous issue, try to fix an empty buffer
+      (when (zerop (buffer-size))
+        (goto-char (point-min))
+        (insert-char ?\())
+      ;; the above left a '(' danlging or crashed and
+      ;; emacs_lisp_error_reporter::finish() haven't been called yet
+      (goto-char (point-min))
+      (when (eq (char-after 1) ?\()
+        (goto-char (point-max))
+        (insert-char ?\)))))
+  (condition-case nil
+      (flymake-quicklintjs--report qljs-stdout-buf src-buf report-fn)
+    (funcall report-fn '())))
+
+(defun flymake-quicklintjs--report (qljs-stdout-buf src-buf report-fn)
+  "Call REPORT-FN to highlight reports in SRC_BUF reported in QLJS-STDOUT-BUF.
+QLJS-STDOUT-BUF is entirely read and it's expected to be in
+QUICKLINTJS-OUTPUT-ALIST format."
+  (with-current-buffer qljs-stdout-buf
+    (funcall report-fn
+             (flymake-quicklintjs--make-diagnostics
+              src-buf
+              (car (read-from-string
+                    (buffer-substring-no-properties (point-min)
+                                                    (point-max))))))))
+
 ;;;###autoload
 (defun flymake-quicklintjs (report-fn &rest _args)
   "Flymake backend for quick-lint-js linter.
-This backend uses `flymake-quicklintjs-program' (which see) to launch a
-quick-lint-js process that is passed the current buffer's contents via stdin.
+This backend uses `quicklintjs-find-program' to find and launch a quick-lint-js
+process that is passed the current buffer's contents via stdin.
 REPORT-FN is Flymake's callback."
   (when (process-live-p flymake-quicklintjs--proc)
     (kill-process flymake-quicklintjs--proc))
-  (let ((src-buf (current-buffer)))
-    (setq flymake-quicklintjs--proc
-          (make-process
-           :name "flymake-quicklintjs"
-           :connection-type 'pipe
-           :noquery t
-           :buffer (get-buffer-create " *flymake-quicklintjs*")
-           :command (quicklintjs-find-program
-                     (let ((file (buffer-file-name)))
-                       (when file (concat "--path-for-config-search=" file)))
-                      "--stdin" "--output-format=emacs-lisp")
-           :sentinel
-           (lambda (p _ev)
-             (unwind-protect
-                 (when (and (eq 'exit (process-status p))
-                            (eq p flymake-quicklintjs--proc))
-                   (with-current-buffer (process-buffer p)
-                     (let ((diags (flymake-quicklintjs--make-diagnostics
-                                  src-buf
-                                  (car (read-from-string
-                                        (buffer-substring-no-properties
-                                         (point-min) (point-max)))))))
-                       (if (or diags (zerop (process-exit-status p)))
-                           (funcall report-fn diags)
-                         (funcall report-fn
-                                  :panic :explanation
-                                  (buffer-substring
-                                   (point-min) (progn (goto-char (point-min))
-                                                      (line-end-position))))))))
-               (unless (process-live-p p)
-                 (kill-buffer (process-buffer p)))))))
-    (process-send-region flymake-quicklintjs--proc (point-min) (point-max))
-    (process-send-eof flymake-quicklintjs--proc)))
+  (let ((src-buf (current-buffer))
+        (stdout-buf (generate-new-buffer " *flymake-quicklintjs-stdout*"))
+        (stderr-buf (generate-new-buffer " *flymake-quicklintjs-stderr*")))
+    (save-restriction
+      (widen)
+      (setq flymake-quicklintjs--proc
+            (make-process
+             :name "flymake-quicklintjs"
+             :connection-type 'pipe
+             :noquery t
+             :buffer stdout-buf
+             :stderr stderr-buf
+             :command (quicklintjs-find-program
+                       (let ((file (buffer-file-name)))
+                         (when file (concat "--path-for-config-search=" file)))
+                       "--stdin" "--output-format=emacs-lisp")
+             :sentinel
+             (lambda (p _ev)
+               (let ((proc-status (process-status p)))
+                 (unwind-protect
+                     (when (and (or (eq proc-status 'exit)
+                                    (eq proc-status 'signal))
+                                (with-current-buffer src-buf
+                                  (eq p flymake-quicklintjs--proc)))
+                       (if (zerop (process-exit-status p))
+                           (flymake-quicklintjs--report stdout-buf
+                                                        src-buf
+                                                        report-fn)
+                         (flymake-quicklintjs--report-with-crash
+                          stdout-buf stderr-buf src-buf report-fn)))
+                   (progn (kill-buffer stdout-buf)
+                          (kill-buffer stderr-buf)))))))
+      (process-send-region flymake-quicklintjs--proc (point-min) (point-max))
+      (process-send-eof flymake-quicklintjs--proc))))
 
 (provide 'flymake-quicklintjs)
 

src/emacs-lisp-error-reporter.cpp

@@ -82,6 +82,7 @@ void emacs_lisp_error_formatter::write_after_message(severity sev,
     return;
   }
   this->output_ << "\")";
+  this->output_.flush();
 }
 }