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[PATCH 1/8] xfsprogs: Fix setbitval() bug when nbits is byte-aligned

To: xfs@xxxxxxxxxxx
Subject: [PATCH 1/8] xfsprogs: Fix setbitval() bug when nbits is byte-aligned
From: Alex Elder <aelder@xxxxxxx>
Date: Thu, 10 Nov 2011 14:35:11 -0600
Cc: Kevan Rehm <kfr@xxxxxxx>, Alex Elder <aelder@xxxxxxx>
In-reply-to: <1320957318-16269-1-git-send-email-aelder@xxxxxxx>
References: <1320957318-16269-1-git-send-email-aelder@xxxxxxx>
From: Kevan Rehm <kfr@xxxxxxx>

If a field whose size is not an even multiple of 8 bits happens to
be aligned on a byte boundary and the machine is little-endian,
routine setbitval() would do a byte copy of zero bytes, effectively
doing nothing.

Catch this case, and arrange for doing the bit setting "the hard
way" (i.e., without using memcpy()) to avoid this problem.

Signed-off-by: Alex Elder <aelder@xxxxxxx>
---
 db/bit.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/db/bit.c b/db/bit.c
index ca57d31..36de0a1 100644
--- a/db/bit.c
+++ b/db/bit.c
@@ -153,7 +153,7 @@ setbitval(
                 */
 
                /* byte aligned ? */
-               if (bitoff%NBBY) {
+               if (bitoff % NBBY || nbits % NBBY) {
                        /* no - bit copy */
                        for (bit=0; bit<nbits; bit++)
                                setbit(out, bit+bitoff, getbit(in, bit));
-- 
1.7.6.4

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