From: Darrick J. Wong <djwong@xxxxxxxxxx>
The Unicode code point for "zero width joiners" (aka 0x200D) is used to
hint to renderers that a sequence of simple code points should be
combined into a more complex rendering. This is how compound emoji such
as "wounded heart" are composed out of "heart" and "bandaid"; and how
complex glyphs are rendered in Malayam.
Emoji in filenames are a supported usecase, so stop warning about the
mere existence of ZWJ. We already warn about ZWJ that are used to
produce confusingly rendered names in a single namespace, so we're not
losing any robustness here.
Cc: <linux-xfs@xxxxxxxxxxxxxxx> # v6.10.0
Fixes: d43362c78e3e37 ("xfs_scrub: store bad flags with the name entry")
Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
---
scrub/unicrash.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/scrub/unicrash.c b/scrub/unicrash.c
index 143060b569f27c..b83bef644b6dce 100644
--- a/scrub/unicrash.c
+++ b/scrub/unicrash.c
@@ -508,8 +508,14 @@ name_entry_examine(
if (is_nonrendering(uchr))
ret |= UNICRASH_INVISIBLE;
- /* control characters */
- if (u_iscntrl(uchr))
+ /*
+ * Warn about control characters in filenames except for zero
+ * width joiners because those are used to construct compound
+ * emoji and glyphs in various languages. ZWJ is already
+ * covered by UNICRASH_INVISIBLE, so we can detect its use in
+ * confusing names.
+ */
+ if (uchr != 0x200D && u_iscntrl(uchr))
ret |= UNICRASH_CONTROL_CHAR;
switch (u_charDirection(uchr)) {
