On 2019-11-14 17:48, Martin Schulte wrote:
> Hello,
>
> I create files t<n> (n=1,3,5,7) with ctime=now and atime=now+<n> days:
>
> $ uname -a
> $ echo
> $ find --version
> $ for d in 1 3 5 7; do
>> touch -a -d "$(date -d "$d day" '+%Y-%m-%d %H:%M:%S')" t$d
>> done
> $ echo
> $ echo find:
> $ find . -name 't?' -used +4
> $ echo done.
>
> I expect
> ./t5
> ./t7
> as output from find but I get nothing:
>
> Linux martnix4 4.9.0-11-amd64 #1 SMP Debian 4.9.189-3+deb9u1 (2019-09-20)
> x86_64 GNU/Linux
>
> find (GNU findutils) 4.7.0-git
> Copyright (C) 2016 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>. This is free software: you are free
> to change and redistribute it. There is NO WARRANTY, to the extent
> permitted by law.
>
> Written by Eric B. Decker, James Youngman, and Kevin Dalley.
> Features enabled: D_TYPE O_NOFOLLOW(enabled) LEAF_OPTIMISATION FTS
> (FTS_CWDFD) CBO(level=2)
>
> find:
> done.
>
> Do I misunderstand the man page? If this is a bug, it looks as if
> pred_used calls pred_timewindow with a bad second argument (absolute time
> iso relative to ctime).
>
> Best regards,
>
> Martin
Thank you for the bug report.
First of all, I have the impression that the -used predicate may often
suffer from 'noatime' or 'relatime' mounts nowadays.
Re. the problem: after a quick look at the sources I see 2 problems:
a) the 'timespec delta' is reversed.
It seems that this bug sneaked somehow in during the introduction of
sub-second timestamp resolution back in 2007.
b) the function pred_used should return false if atime < ctime.
Such a condition has to be added because the -used predicate shall
evaluate to true:
1. with "-used -N": if atime is less than N days after ctime.
2. with "-used N": if atime is exactly N days after ctime.
3. with "-used +N": if atime is more than N days after ctime.
Therefore, if atime is before ctime, then -used with any argument
should evaluate to false.
The attached (raw git diff) fixes both.
Your test case would then look like the following:
$ rm t* # remove because otherwise 'touch' would always also set the ctime.
$ for d in 1 3 5 7; do \
touch -a -d "$(date -d "$d day" '+%Y-%m-%d %H:%M:%S')" t$d ; \
done
$ stat -c "Name: %n Access: %x Change: %z" t?
Name: t1 Access: 2019-11-18 23:04:17.000000000 +0100 Change: 2019-11-17
23:04:17.147805944 +0100
Name: t3 Access: 2019-11-20 23:04:17.000000000 +0100 Change: 2019-11-17
23:04:17.151806001 +0100
Name: t5 Access: 2019-11-22 23:04:17.000000000 +0100 Change: 2019-11-17
23:04:17.155806059 +0100
Name: t7 Access: 2019-11-24 23:04:17.000000000 +0100 Change: 2019-11-17
23:04:17.159806116 +0100
$ for f in -8 -7 -6 -5 -4 -3 -2 -1 -0 0 +0 +1 +2 +3 +4 +5 +6 +7 +8; do \
set -x ; \
find . -type f -used $f; \
{ set +x; } 2>/dev/null; \
done
+ find . -type f -used -8
./t7
./t5
./t3
./t1
+ find . -type f -used -7
./t7
./t5
./t3
./t1
+ find . -type f -used -6
./t5
./t3
./t1
+ find . -type f -used -5
./t5
./t3
./t1
+ find . -type f -used -4
./t3
./t1
+ find . -type f -used -3
./t3
./t1
+ find . -type f -used -2
./t1
+ find . -type f -used -1
./t1
+ find . -type f -used -0
+ find . -type f -used 0
+ find . -type f -used +0
./t7
./t5
./t3
./t1
+ find . -type f -used +1
./t7
./t5
./t3
+ find . -type f -used +2
./t7
./t5
./t3
+ find . -type f -used +3
./t7
./t5
+ find . -type f -used +4
./t7
./t5
+ find . -type f -used +5
./t7
+ find . -type f -used +6
./t7
+ find . -type f -used +7
+ find . -type f -used +8
I'll try to come up with a proper patch - maybe including a test
case - in the next few days (although a look into my calendar for this
week doesn't leave much hope for this).
Have a nice day,
Berny
diff --git a/find/pred.c b/find/pred.c
index 688103d6..9d7b0a0e 100644
--- a/find/pred.c
+++ b/find/pred.c
@@ -1166,8 +1166,13 @@ pred_used (const char *pathname, struct stat *stat_buf, struct predicate *pred_p
/* TODO: this needs to be retested carefully (manually, if necessary) */
at = get_stat_atime (stat_buf);
ct = get_stat_ctime (stat_buf);
- delta.tv_sec = at.tv_sec - ct.tv_sec;
- delta.tv_nsec = at.tv_nsec - ct.tv_nsec;
+
+ /* Always evaluate to false if aime < ctime. */
+ if (compare_ts (at, ct) < 0)
+ return false;
+
+ delta.tv_sec = ct.tv_sec - at.tv_sec;
+ delta.tv_nsec = ct.tv_nsec - at.tv_nsec;
if (delta.tv_nsec < 0)
{
delta.tv_nsec += 1000000000;
