[PATCH] oc-basic: Detect malformed bibtex bibliographies

[Ihor Radchenko <yantar92@gmail.com>]

There is an edge case triggering infinite loop in oc-basic.

It is caused by bibtex-map-entries (used in
org-cite-basic--parse-bibtex) when ran on a malformed bibtex buffer [1].

The proposed patch validates the bibtex buffer before processing and
throws an error if issues are found.  `bibtex-validate` also
conveniently displays a list of errors with clickable links to
problematic lines.

I believe that it is useful for the users to see such issues instead of,
say, failing silently on malformed bibliographies.

WDYT?

Best,
Ihor

[1] https://debbugs.gnu.org/cgi/bugreport.cgi?bug=55036

* lisp/oc-basic.el (org-cite-basic--parse-bibtex): Validate the
bibliography before parsing.  Display list of issues if any (via
`bibtex-validate`).
(org-cite-basic--parse-bibliography): Set buffer file name needed by
`bibtex-validate`.  Empty the cache in case of error.
---
 lisp/oc-basic.el | 38 ++++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 14 deletions(-)

diff --git a/lisp/oc-basic.el b/lisp/oc-basic.el
index 873986d07..79f7a4844 100644
--- a/lisp/oc-basic.el
+++ b/lisp/oc-basic.el
@@ -214,6 +214,10 @@ (defun org-cite-basic--parse-bibtex (dialect)
   (let ((entries (make-hash-table :test #'equal))
         (bibtex-sort-ignore-string-entries t))
     (bibtex-set-dialect dialect t)
+    ;; Throw an error if bibliography is malformed.
+    (unless (bibtex-validate)
+      (user-error "Malformed bibliography at %S"
+                  (or (buffer-file-name) (current-buffer))))
     (bibtex-map-entries
      (lambda (key &rest _)
        ;; Normalize entries: field names are turned into symbols
@@ -258,21 +262,27 @@ (defun org-cite-basic--parse-bibliography (&optional info)
             (when (or (org-file-has-changed-p file)
                       (not (gethash file org-cite-basic--file-id-cache)))
               (insert-file-contents file)
+              (setf (buffer-file-name) file)
               (puthash file (org-buffer-hash) org-cite-basic--file-id-cache))
-	    (let* ((file-id (cons file (gethash file org-cite-basic--file-id-cache)))
-                   (entries
-                    (or (cdr (assoc file-id org-cite-basic--bibliography-cache))
-                        (let ((table
-                               (pcase (file-name-extension file)
-                                 ("json" (org-cite-basic--parse-json))
-                                 ("bib" (org-cite-basic--parse-bibtex 'biblatex))
-                                 ("bibtex" (org-cite-basic--parse-bibtex 'BibTeX))
-                                 (ext
-                                  (user-error "Unknown bibliography extension: %S"
-                                              ext)))))
-                          (push (cons file-id table) org-cite-basic--bibliography-cache)
-                          table))))
-              (push (cons file entries) results)))))
+            (unwind-protect
+                (condition-case nil
+                    (unwind-protect
+	                (let* ((file-id (cons file (gethash file org-cite-basic--file-id-cache)))
+                               (entries
+                                (or (cdr (assoc file-id org-cite-basic--bibliography-cache))
+                                    (let ((table
+                                           (pcase (file-name-extension file)
+                                             ("json" (org-cite-basic--parse-json))
+                                             ("bib" (org-cite-basic--parse-bibtex 'biblatex))
+                                             ("bibtex" (org-cite-basic--parse-bibtex 'BibTeX))
+                                             (ext
+                                              (user-error "Unknown bibliography extension: %S"
+                                                          ext)))))
+                                      (push (cons file-id table) org-cite-basic--bibliography-cache)
+                                      table))))
+                          (push (cons file entries) results))
+                      (setf (buffer-file-name) nil))
+                  (error (setq org-cite-basic--file-id-cache nil)))))))
       (when info (plist-put info :cite-basic/bibliography results))
       results)))
 
-- 
2.35.1



-- 
Ihor Radchenko,
PhD,
Center for Advancing Materials Performance from the Nanoscale (CAMP-nano)
State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China
Email: yantar92@gmail.com, ihor_radchenko@alumni.sutd.edu.sg