Fix ietf-drums-remove-whitespace unmatched " and (

* lisp/mail/ietf-drums.el:
+ (ietf-drums-skip-comment):  New helper function.
+ (ietf-drums-remove-comments):  Use ietf-drums-skip-comment.
+ (ietf-drums-remove-whitespace):  Handle unterminated quotes and
comments, as ietf-drums-remove-comments already does.
* test/lisp/mail/ietf-drums-tests.el:
+ Test unterminated quote and comment for
ietf-drums-remove-whitespace and ietf-drums-remove-comments (bug#53965).

2 files changed, 36 insertions, 10 deletions

diff --git a/lisp/mail/ietf-drums.el b/lisp/mail/ietf-drums.el
index db77aba172f..85aa27235fc 100644
--- a/lisp/mail/ietf-drums.el
+++ b/lisp/mail/ietf-drums.el
@@ -65,6 +65,21 @@ backslash and doublequote.")
     (modify-syntax-entry ?\' "_" table)
     table))
 
+(defvar ietf-drums-comment-syntax-table
+  (let ((table (copy-syntax-table ietf-drums-syntax-table)))
+    (modify-syntax-entry ?\" "w" table)
+    table)
+  "In comments, DQUOTE is normal and does not start a string.")
+
+(defun ietf-drums--skip-comment ()
+  ;; From just before the start of a comment, go to the end.  Returns
+  ;; point.  If the comment is unterminated, go to point-max.
+  (condition-case ()
+      (with-syntax-table ietf-drums-comment-syntax-table
+        (forward-sexp 1))
+    (scan-error (goto-char (point-max))))
+  (point))
+
 (defun ietf-drums-token-to-list (token)
   "Translate TOKEN into a list of characters."
   (let ((i 0)
@@ -109,14 +124,7 @@ backslash and doublequote.")
               (forward-sexp 1)
             (error (goto-char (point-max)))))
          ((eq c ?\()
-          (delete-region
-               (point)
-               (condition-case nil
-                   (with-syntax-table (copy-syntax-table ietf-drums-syntax-table)
-                     (modify-syntax-entry ?\" "w")
-                     (forward-sexp 1)
-                     (point))
-                 (error (point-max)))))
+          (delete-region (point) (ietf-drums--skip-comment)))
          (t
           (forward-char 1))))
       (buffer-string))))
@@ -130,9 +138,11 @@ backslash and doublequote.")
         (setq c (char-after))
         (cond
          ((eq c ?\")
-          (forward-sexp 1))
+          (condition-case ()
+              (forward-sexp 1)
+            (scan-error (goto-char (point-max)))))
          ((eq c ?\()
-          (forward-sexp 1))
+          (ietf-drums--skip-comment))
          ((memq c '(?\  ?\t ?\n ?\r))
           (delete-char 1))
          (t
diff --git a/test/lisp/mail/ietf-drums-tests.el b/test/lisp/mail/ietf-drums-tests.el
index 4cc38b8763a..b13937bf736 100644
--- a/test/lisp/mail/ietf-drums-tests.el
+++ b/test/lisp/mail/ietf-drums-tests.el
@@ -40,6 +40,16 @@
   (should (equal (ietf-drums-remove-comments
                   "random (first) (second (and)) (third) not fourth")
                  "random    not fourth"))
+  ;; Test some unterminated comments.
+  (should (equal (ietf-drums-remove-comments "test an (unterminated comment")
+                 "test an "))
+  (should (equal (ietf-drums-remove-comments "test an \"unterminated quote")
+                 ;; returns the string unchanged (and doesn't barf).
+                 "test an \"unterminated quote"))
+  (should (equal (ietf-drums-remove-comments
+                  ;; note that double-quote is not special.
+                  "test (unterminated comments with \"quoted (\" )stuff")
+                 "test "))
 
   ;; ietf-drums-remove-whitespace
   (should (equal (ietf-drums-remove-whitespace "random string")
@@ -53,6 +63,12 @@
   (should (equal (ietf-drums-remove-whitespace
                   "random (first) (second (and)) (third) not fourth")
                  "random(first)(second (and))(third)notfourth"))
+  ;; Test some unterminated comments and quotes.
+  (should (equal (ietf-drums-remove-whitespace
+                  "random (first) (second (and)) (third unterminated")
+                 "random(first)(second (and))(third unterminated"))
+  (should (equal (ietf-drums-remove-whitespace "random \"non terminated string")
+                 "random\"non terminated string"))
 
   ;; ietf-drums-strip
   (should (equal (ietf-drums-strip "random string") "randomstring"))