Re: [PATCH v6 16/16] scripts/oss-fuzz: remove the generic-fuzz target

From: Alexander Bulekov <alxndr@bu.edu>
To: Darren Kenny <darren.kenny@oracle.com>
Cc: Thomas Huth <thuth@redhat.com>,
	qemu-devel@nongnu.org, f4bug@amsat.org, bsd@redhat.com,
	stefanha@redhat.com, pbonzini@redhat.com,
	dimastep@yandex-team.ru
Subject: Re: [PATCH v6 16/16] scripts/oss-fuzz: remove the generic-fuzz target
Date: Thu, 22 Oct 2020 09:01:23 -0400	[thread overview]
Message-ID: <20201022130123.5bjijh5cupwujeox@mozz.bu.edu> (raw)
In-Reply-To: <m2o8ku7ghw.fsf@oracle.com>

On 201022 1032, Darren Kenny wrote:
> Hi Alex,
> 
> On Wednesday, 2020-10-21 at 17:09:22 -04, Alexander Bulekov wrote:
> > generic-fuzz is not a standalone fuzzer - it requires some env variables
> > to be set. On oss-fuzz, we set these with some predefined
> > generic-fuzz-{...} targets, that are thin wrappers around generic-fuzz.
> > Remove generic-fuzz from the oss-fuzz build, so oss-fuzz does not treat
> > it as a standalone fuzzer.
> >
> > Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> > ---
> >  scripts/oss-fuzz/build.sh | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/scripts/oss-fuzz/build.sh b/scripts/oss-fuzz/build.sh
> > index 0c3ca9e06f..37cd7f9e25 100755
> > --- a/scripts/oss-fuzz/build.sh
> > +++ b/scripts/oss-fuzz/build.sh
> > @@ -97,5 +97,11 @@ do
> 

Hi Darren,

> I'm presuming that the target that you're removing is being created by
> this line, maybe we should just specifically skip it here instead?

Sounds good.

> The comment below on the removal probably would still apply though.
> 
> >      cp qemu-fuzz-i386 "$DEST_DIR/qemu-fuzz-i386-target-$target"
> 
> Also, did you look into using hard-links, or even sym-links - they would
> require less duplication of the binaries, which may be important, or may
> not, and quicker creation too, e.g.
> 
>       ln qemu-fuzz-i386 "$DEST_DIR/qemu-fuzz-i386-target-$target"

This is what I tried, when I was putting together the patch-series, and
it raised an error when I was testing it in the oss-fuzz
docker-containers. I blamed it on Docker, originally, but I just took a
closer look, and the problem was that "qemu-fuzz-i386" isn't on the same
file-system as $DEST_DIR in the oss-fuzz Docker. If I copy
qemu-fuzz-i386 to $DEST_DIR/lib, and do 
    ln "$DEST_DIR/lib/qemu-fuzz-i386" \
       "$DEST_DIR/qemu-fuzz-i386-target-$target"
everything works :)
Thanks
-Alex

> 
> It's something that has been done for years, for example if you do:
> 
>       ls -il /sbin/{e2fsck,fsck.ext*}
> 
> you will see they share the same inode. Similarly for vi and ex, they
> use symlinks (hardlinks on some OSes, but seems not Linux):
> 
>       ls -il /bin/{vi,ex}
> 
> The main point is that argv[0] will be the name of link itself, not the
> thing pointed to.
> 
> Thanks,
> 
> Darren.
> 
> >  done
> >  
> > +# Remove the generic-fuzz target, as it requires some environment variables to
> > +# be configured. We have some generic-fuzz-{pc-q35, floppy, ...} targets that
> > +# are thin wrappers around this target that set the required environment
> > +# variables according to predefined configs.
> > +rm "$DEST_DIR/qemu-fuzz-i386-target-generic-fuzz"
> > +
> >  echo "Done. The fuzzers are located in $DEST_DIR"
> >  exit 0
> > -- 
> > 2.28.0