emacs-29 6f9ea396f49 06/11: org-latex-preview: Add protection when `untrusted-content' is non-nil

[Eli Zaretskii]

branch: emacs-29
commit 6f9ea396f49cbe38c2173e0a72ba6af3e03b271c
Author: Ihor Radchenko <yantar92@posteo.net>
Commit: Eli Zaretskii <eliz@gnu.org>

    org-latex-preview: Add protection when `untrusted-content' is non-nil
    
    * lisp/org/org.el (org--latex-preview-when-risky): New variable
    controlling how to handle LaTeX previews in Org files from untrusted
    origin.
    (org-latex-preview): Consult `org--latex-preview-when-risky' before
    generating previews.
    
    This patch adds a layer of protection when LaTeX preview is requested
    for an email attachment, where `untrusted-content' is set to non-nil.
---
 lisp/org/org.el | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/lisp/org/org.el b/lisp/org/org.el
index c75afbf5a67..0f5d17deee2 100644
--- a/lisp/org/org.el
+++ b/lisp/org/org.el
@@ -1140,6 +1140,24 @@ the following lines anywhere in the buffer:
   :package-version '(Org . "8.0")
   :type 'boolean)
 
+(defvar untrusted-content) ; defined in files.el
+(defvar org--latex-preview-when-risky nil
+  "If non-nil, enable LaTeX preview in Org buffers from unsafe source.
+
+Some specially designed LaTeX code may generate huge pdf or log files
+that may exhaust disk space.
+
+This variable controls how to handle LaTeX preview when rendering LaTeX
+fragments that originate from incoming email messages.  It has no effect
+when Org mode is unable to determine the origin of the Org buffer.
+
+An Org buffer is considered to be from unsafe source when the
+variable `untrusted-content' has a non-nil value in the buffer.
+
+If this variable is non-nil, LaTeX previews are rendered unconditionally.
+
+This variable may be renamed or changed in the future.")
+
 (defcustom org-insert-mode-line-in-empty-file nil
   "Non-nil means insert the first line setting Org mode in empty files.
 When the function `org-mode' is called interactively in an empty file, this
@@ -15695,6 +15713,7 @@ fragments in the buffer."
   (interactive "P")
   (cond
    ((not (display-graphic-p)) nil)
+   ((and untrusted-content (not org--latex-preview-when-risky)) nil)
    ;; Clear whole buffer.
    ((equal arg '(64))
     (org-clear-latex-preview (point-min) (point-max))