bug#10293: [PATCH] du -x should not count files in other file systems

[Jim Meyering]

Paul Eggert wrote:
> While looking into Bug#10282 I noticed that 'du' is mishandling
> the -x option.  It relies on FTS_XDEV to not cross file system boundaries,
> but FTS_XDEV visits the root of the other file system, causing
> 'du' to output a line "0 X" where X is the mount point of the
> other file system.  This doesn't sound right, since X is in a
> different file system and du -x is supposed to ignore files in
> other file systems.  Also, it disagrees with Solaris 10 du
> (at least).
>
> Here's a proposed patch.  The bug is absent from coreutils 5.0
> and present in 5.2.0.  I'm guessing from the NEWS files that
> it was introduced in 5.1.0 but 5.1.0 is no longer available
> at ftp.gnu.org so this isn't trivial for me to check.
>
> du: -x should not count files in other file systems
> * NEWS: Document fix.
> * src/du.c (process_file): Don't count files in different file
> systems if -x is given.
> * tests/du/one-file-system: Test for this bug.

Thanks for noticing/fixing that.  The fix looks fine.
Please include in the commit log the SHA1 that probably induced the bug.
Also, a small improvement to the test script below:

> diff --git a/NEWS b/NEWS
...
> diff --git a/tests/du/one-file-system b/tests/du/one-file-system
...
> +# "du -xL" reported a zero count for a file in a different file system,
> +# instead of ignoring it.
> +du -xL d > u || fail=1
> +sed 's/^[0-9][0-9]*  //' u > out1
> +cat <<\EOF > exp1 || fail=1
> +d
> +EOF

The three lines above can be replaced by this one:

echo d > exp1 || fail=1

> +compare exp1 out1 || fail=1
> +
>  Exit $fail