du: exclude non-directories under -t threshold

[naman_freebsdfoundation.org]

Summary

Fixes the issue highlighted in https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=265200.

Test Plan

Regression test included in commit.

[jrm]

Before patch:

% du -aht 20000000 /bin
8.5K    /bin/ln
8.5K    /bin/chflags
8.5K    /bin/rm
8.5K    /bin/test
8.5K    /bin/timeout
 21K    /bin/dd
 13K    /bin/cp
 69K    /bin/pax
4.5K    /bin/freebsd-version
8.5K    /bin/cat
4.5K    /bin/mkdir
 13K    /bin/pkill
 13K    /bin/expr
305K    /bin/csh
 37K    /bin/ed
 45K    /bin/rmail
 25K    /bin/ls
 13K    /bin/date
 13K    /bin/setfacl
8.5K    /bin/getfacl
4.5K    /bin/rmdir
125K    /bin/sh
4.5K    /bin/domainname
4.5K    /bin/pwd
8.5K    /bin/uuidgen
8.5K    /bin/nproc
 21K    /bin/stty
8.5K    /bin/kenv
 33K    /bin/ps
4.5K    /bin/echo
4.5K    /bin/realpath
4.5K    /bin/hostname
8.5K    /bin/sleep
 13K    /bin/mv
8.5K    /bin/chmod
4.5K    /bin/sync
8.5K    /bin/pwait
 13K    /bin/df
8.5K    /bin/kill
 13K    /bin/chio

After patch:

# /usr/obj/usr/src/amd64.amd64/usr.bin/du/du -aht 20000000 /bin
#

usr.bin/du/du.c

323–326

DU(1) says

-t threshold
        Display only entries for which size exceeds threshold.

% du -ah | sort -n
4.0K    ./Makefile
4.0K    ./Makefile.depend
4.0K    ./tests/Makefile
4.0K    ./tests/Makefile.depend
8.0K    ./du.1
8.0K    ./tests/du_test.sh
 16K    ./du.c
 20K    ./tests
 56K    .

% du -ah -t 4k | sort -n
4.0K    ./Makefile
4.0K    ./Makefile.depend
4.0K    ./tests/Makefile
4.0K    ./tests/Makefile.depend
8.0K    ./du.1
8.0K    ./tests/du_test.sh
 16K    ./du.c
 20K    ./tests
 56K    .

% du -ah -t 5k | sort -n
8.0K    ./du.1
8.0K    ./tests/du_test.sh
 16K    ./du.c
 20K    ./tests
 56K    .

Since the manpage says only files with a size *exceeding* the threshold will be displayed, shouldn't the 4K files be excluded with -t 4k?

DU(1) from coreutils 9.3 says,

-t, --threshold=SIZE
       exclude entries smaller than SIZE

which implies that files with a size equal to the threshold will be displayed. This is indeed the case.

% du -ab /etc/X11 | sort -n
0       /etc/X11/xorg.conf.d
318     /etc/X11/xinit/xinitrc.d/40-libcanberra-gtk-module.sh
538     /etc/X11/xinit/xinitrc.d/50-systemd-user.sh
856     /etc/X11
856     /etc/X11/xinit
856     /etc/X11/xinit/xinitrc.d
%

% du -ab /etc/X11 -t 856 | sort -n
856     /etc/X11
856     /etc/X11/xinit
856     /etc/X11/xinit/xinitrc.d
%

% du -ab /etc/X11 -t 857 | sort -n
%

(The -b flag in coreutils du says it's "equivalent to '--apparent-size --block-size=1'". We require a minimum block size of 512, so we can't do the same comparison.)

I think the best thing to do is update our man page to say something like this.

-t threshold
        Exclude entries smaller than threshold.

[naman_freebsdfoundation.org]

Made requested changes, and updated base revision.

• use -h for consistent test output
• update man page to correctly reflect -t behavior
• fix typo in test
• Merge branch 'main' into du-at