Re: [PATCH] test: Fix the escaping issue in memory/passt test

[Stefano Brivio <sbrivio@redhat.com>]

On Wed, 15 Oct 2025 16:04:02 +0800
Yumei Huang <yuhuang@redhat.com> wrote:

> Test memory/passt failed with error "objsize: No such file or
> directory" because of an escaping issue. Fix it.

Sorry for the delay.

I tested the patch and it works for me, it simply adds a \ at the
beginning of the line, and that print simply shows results in the test
log. The output is not used in any automated way.

But I never ran into the issue, so I was looking for an explanation for
this:

> Link: https://bugs.passt.top/show_bug.cgi?id=155
> Signed-off-by: Yumei Huang <yuhuang@redhat.com>
> ---
>  test/memory/passt | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/test/memory/passt b/test/memory/passt
> index 7e45724..c5142ea 100644
> --- a/test/memory/passt
> +++ b/test/memory/passt
> @@ -51,7 +51,7 @@ guest	sed /proc/slabinfo -ne 's/^\([^ ]* *[^ ]* *[^ ]* *[^ ]*\).*/\\\1/p' > /tmp
>  guest	kill \$(cat /tmp/pid)
>  guest	diff -y --suppress-common-lines /tmp/meminfo.before /tmp/meminfo.after || :
>  guest	nm -td -Sr --size-sort -P /bin/passt.avx2 | head -30 | tee /tmp/nm.size
> -guest	sed /proc/slabinfo -ne 's/\(.*<objsize>\).*$/\1/p' | tail -1; (diff -y --suppress-common-lines /tmp/slabinfo.before /tmp/slabinfo.after | sort -grk8)
> +guest	sed /proc/slabinfo -ne 's/\(.*<objsize>\).*$/\\\1/p' | tail -1; (diff -y --suppress-common-lines /tmp/slabinfo.before /tmp/slabinfo.after | sort -grk8)

Without the \ at the beginning, we have this line:

# name            <active_objs> <num_objs> <objsize>

and... maybe you have a file in the directory where you run the tests
that's called num_objs, or objsize, created as a result of a previous
failure (and some other issue), and '<objsize' is not escaped somewhere
so it's taken as a redirection?

Perhaps a \# at the beginning, instead of #, makes Bash ignore the
whole line, and for some reason it's not ignored otherwise?

It shouldn't have anything to do with the guest image because that's
read-only.

Could you have a look if you see any "strange" file name in your test
directory?

Otherwise I would be tempted to just go ahead and apply this because
it's harmless and it's not *that* important that we find a solution to
this. We're going to rewrite this test eventually.

-- 
Stefano