Re: Form feed characters break odt export

[Ihor Radchenko]

Christian Moe <mail@christianmoe.com> writes:

> I don't think it's specific to ODT or LibreOffice, it's the underlying
> XML 1.0 spec that "discourages" control characters and does not include
> #xC in the range of characters that XML processors must accept.
>
> Spec: https://www.w3.org/TR/REC-xml/#charsets
>
> Some discussion:
> https://stackoverflow.com/questions/404107/why-are-control-characters-illegal-in-xml-1-0

Thanks!
Then, we can simply remove the disallowed characters.
See the attached tentative patch.

>From 5c9fdd9df32b87be9f81e037336332984bc3b16c Mon Sep 17 00:00:00 2001
Message-ID: 
<5c9fdd9df32b87be9f81e037336332984bc3b16c.1735049605.git.yantar92@posteo.net>
From: Ihor Radchenko <yantar92@posteo.net>
Date: Tue, 24 Dec 2024 15:11:22 +0100
Subject: [PATCH] ox-odt: Avoid putting forbidden  characters into ODT xml

* lisp/ox-odt.el (org-odt-forbidden-char-re):
(org-odt-discouraged-char-re): New constants codifying characters that
are prohibited in XML spec.
(org-odt--remove-forbidden): New function removing the prohibited
characters.
(org-odt--encode-plain-text): Remove the prohibited characters.
(org-odt-plain-text): Update comment.

Reported-by: Joseph Turner <joseph@breatheoutbreathe.in>
Link: 87o711l4u4.fsf@christianmoe.com">https://orgmode.org/list/87o711l4u4.fsf@christianmoe.com
---
 lisp/ox-odt.el | 38 +++++++++++++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

diff --git a/lisp/ox-odt.el b/lisp/ox-odt.el
index ec81637ef0..61c8d4ec75 100644
--- a/lisp/ox-odt.el
+++ b/lisp/ox-odt.el
@@ -170,6 +170,28 @@ (defconst org-odt-special-string-regexps
     ("\\.\\.\\." . "&#x2026;"))                ; hellip
   "Regular expressions for special string conversion.")
 
+(defconst org-odt-forbidden-char-re
+  (rx (not (in ?\N{U+9} ?\N{U+A} ?\N{U+D}
+             (?\N{U+20} . ?\N{U+D7FF})
+             (?\N{U+E000} . ?\N{U+FFFD})
+             (?\N{U+10000} . ?\N{U+10FFFF}))))
+  "Regexp matching forbidden XML1.0 characters.
+https://www.w3.org/TR/REC-xml/#charsets";)
+
+(defconst org-odt-discouraged-char-re
+  (rx (in (?\N{U+7F} . ?\N{U+84}) (?\N{U+86} . ?\N{U+9F})
+         (?\N{U+FDD0} . ?\N{U+FDEF}) (?\N{U+1FFFE} . ?\N{U+1FFFF})
+          (?\N{U+2FFFE} . ?\N{U+2FFFF}) (?\N{U+3FFFE} . ?\N{U+3FFFF})
+         (?\N{U+4FFFE} . ?\N{U+4FFFF}) (?\N{U+5FFFE} . ?\N{U+5FFFF})
+          (?\N{U+6FFFE} . ?\N{U+6FFFF}) (?\N{U+7FFFE} . ?\N{U+7FFFF})
+          (?\N{U+8FFFE} . ?\N{U+8FFFF}) (?\N{U+9FFFE} . ?\N{U+9FFFF})
+         (?\N{U+AFFFE} . ?\N{U+AFFFF}) (?\N{U+BFFFE} . ?\N{U+BFFFF})
+          (?\N{U+CFFFE} . ?\N{U+CFFFF}) (?\N{U+DFFFE} . ?\N{U+DFFFF})
+          (?\N{U+EFFFE} . ?\N{U+EFFFF}) (?\N{U+FFFFE} . ?\N{U+FFFFF})
+         (?\N{U+10FFFE} . ?\N{U+10FFFF})))
+  "Regexp matching discouraged XML1.0 characters.
+https://www.w3.org/TR/REC-xml/#charsets";)
+
 (defconst org-odt-schema-dir-list
   (list (expand-file-name "./schema/" org-odt-data-dir))
   "List of directories to search for OpenDocument schema files.
@@ -2892,18 +2914,28 @@ (defun org-odt--encode-tabs-and-spaces (line)
        (format " <text:s text:c=\"%d\"/>" (1- (length s)))))
    line))
 
+(defun org-odt--remove-forbidden (text)
+  "Remove forbidden and discouraged characters from TEXT.
+https://www.w3.org/TR/REC-xml/#charsets";
+  (replace-regexp-in-string
+   org-odt-forbidden-char-re ""
+   (replace-regexp-in-string
+    org-odt-discouraged-char-re ""
+    text)))
+
 (defun org-odt--encode-plain-text (text &optional no-whitespace-filling)
   (dolist (pair '(("&" . "&amp;") ("<" . "&lt;") (">" . "&gt;")))
     (setq text (replace-regexp-in-string (car pair) (cdr pair) text t t)))
-  (if no-whitespace-filling text
-    (org-odt--encode-tabs-and-spaces text)))
+  (org-odt--remove-forbidden
+   (if no-whitespace-filling text
+     (org-odt--encode-tabs-and-spaces text))))
 
 (defun org-odt-plain-text (text info)
   "Transcode a TEXT string from Org to ODT.
 TEXT is the string to transcode.  INFO is a plist holding
 contextual information."
   (let ((output text))
-    ;; Protect &, < and >.
+    ;; Protect &, < and >, and remove forbidden characters.
     (setq output (org-odt--encode-plain-text output t))
     ;; Handle smart quotes.  Be sure to provide original string since
     ;; OUTPUT may have been modified.
-- 
2.47.1

-- 
Ihor Radchenko // yantar92,
Org mode maintainer,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
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