From: Mark Wooding <mdw@distorted.org.uk>
Date: Mon, 13 Apr 2020 14:16:56 +0000 (+0100)
Subject: el/dot-emacs.el: Remove `noip' from `LD_PRELOAD' list while running `man'.
X-Git-Url: https://git.distorted.org.uk/~mdw/profile/commitdiff_plain/234ade9da911fef971e2938bbf23c322bcdff148

el/dot-emacs.el: Remove `noip' from `LD_PRELOAD' list while running `man'.

Later versions of `man-db' install a `seccomp' filter to prevent stray
manpages from (among other stuff) doing network things.  This interacts
badly with `noip', which wants to fetch the list of network interfaces
at startup.  Since the `man-db' filter is strictly better than what
`noip' is doing, just turn off `noip' while running `man'.
---

diff --git a/el/dot-emacs.el b/el/dot-emacs.el
index d2b9dcc..5bba5d7 100644
--- a/el/dot-emacs.el
+++ b/el/dot-emacs.el
@@ -4441,6 +4441,41 @@ there is sadness."
   (set-window-dedicated-p (or window (selected-window)) nil))
 
 ;;;--------------------------------------------------------------------------
+;;; Man pages.
+
+;; Turn off `noip' when running `man': it interferes with `man-db''s own
+;; seccomp(2)-based sandboxing, which is (in this case, at least) strictly
+;; better.
+(defadvice Man-getpage-in-background
+    (around mdw-inhibit-noip (topic) compile activate)
+  "Inhibit the `noip' preload hack when invoking `man'."
+  (let* ((old-preload (getenv "LD_PRELOAD"))
+	 (preloads (save-match-data (split-string old-preload ":")))
+	 (any nil)
+	 (filtered nil))
+    (while preloads
+      (let ((item (pop preloads)))
+	(if (save-match-data
+	      (string-match  "\\(/\\|^\\)noip\.so\\(:\\|$\\)" item))
+	    (setq any t)
+	  (push item filtered))))
+    (if any
+	(unwind-protect
+	    (progn
+	      (setenv "LD_PRELOAD"
+		      (and filtered
+			   (with-output-to-string
+			     (setq filtered (nreverse filtered))
+			     (let ((first t))
+			       (while filtered
+				 (if first (setq first nil)
+				   (write-char ?:))
+				 (write-string (pop filtered)))))))
+	      ad-do-it)
+	  (setenv "LD_PRELOAD" old-preload))
+      ad-do-it)))
+
+;;;--------------------------------------------------------------------------
 ;;; MPC configuration.
 
 (eval-when-compile (trap (require 'mpc)))