Allow to search for characters whose bidi directionality was overridden.

 src/bidi.c (bidi_find_first_overridden): New function.
 src/xdisp.c (Fbidi_find_overridden_directionality): New function.
 (syms_of_xdisp): Defsubr it.
 src/dispextern.h (bidi_find_first_overridden): Add prototype.

 doc/lispref/display.texi (Bidirectional Display): Document
 'bidi-find-overridden-directionality'.

 etc/NEWS: Mention 'bidi-find-overridden-directionality'.

2 files changed, 11 insertions, 0 deletions

diff --git a/etc/ChangeLog b/etc/ChangeLog
index 09dfd7f2e35..4f672dfce5e 100644
--- a/etc/ChangeLog
+++ b/etc/ChangeLog
@@ -1,3 +1,7 @@
+2014-12-02  Eli Zaretskii  <eliz@gnu.org>
+
+        * NEWS: Mention 'bidi-find-overridden-directionality'.
+
 2014-11-29  Paul Eggert  <eggert@cs.ucla.edu>
 
         Lessen focus on ChangeLog files, as opposed to change log entries.
diff --git a/etc/NEWS b/etc/NEWS
index 6c636cf3095..bb016ee8944 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -98,6 +98,13 @@ environment.  For the time being this is implemented for modern POSIX
 systems and for MS-Windows, for other systems they fall back to their
 counterparts `string-lessp' and `string-equal'.
 
++++
+** The new function `bidi-find-overridden-directionality' allows to
+find characters whose directionality was, perhaps maliciously,
+overridden by directional override control characters.  Lisp programs
+can use this to detect potential phishing of URLs and other links that
+exploits bidirectional display reordering.
+
 *** The ls-lisp package uses `string-collate-lessp' to sort file names.
 If you want the old, locale-independent sorting, customize the new
 option `ls-lisp-use-string-collate' to a nil value.