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[2/3] xfs_scrub: don't warn about zero width joiner control characters

Message ID 174042401309.1205942.12498812873396538376.stgit@frogsfrogsfrogs (mailing list archive)
State New
Headers show
Series [1/3] xfs_scrub: fix buffer overflow in string_escape | expand

Commit Message

Darrick J. Wong Feb. 24, 2025, 7:07 p.m. UTC 
From: Darrick J. Wong <djwong@kernel.org>

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@vger.kernel.org> # v6.10.0
Fixes: d43362c78e3e37 ("xfs_scrub: store bad flags with the name entry")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 scrub/unicrash.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Comments

Christoph Hellwig Feb. 24, 2025, 10:28 p.m. UTC | #1 
Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series

Patch

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)) {