Re: [fuse-devel] Do I need to support both - libfuse2 and libfuse3 in my application in order to work on more Linux distros, in case I deploy libfuse with my application

[Cyril C. <cyr...@gm...>]

> All new features are optional and established at the FUSE_INIT phase

Which are those "all new features"? I mean, what features could be
unsupported by the kernel?

On Tue, Oct 1, 2019 at 3:58 PM Cyril Cyrov <cyr...@gm...> wrote:
>
> Yes, I think I totally get your point.
>
> My point of view is - building libfuse3 on older systems is possible
> and it cost me like 2-3 hours to build the necessary tools. Packing
> fusermount3 in the installer also doesn't sound so hard - we already
> do deploy libfuse.so, that's just one ore file. And finally, patching
> in order to find the fusermount3 binary - this seems like a trivial
> patch.
> Also given the fact, that we rarely update fuse versions, this effort
> seems to worth it.
>
> My two concerns, that I still have, are:
> 1) is there any security risk in deploying fusermount3 and should I do
> anything special, except just copy the binary into the installer?
> 2) how will I understand that the kernel is too old for some feature,
> that I need (I get it, that it's during the FUSE_INIT phase, I'll have
> to read more about this).
>
> On Tue, Oct 1, 2019 at 3:19 PM Antonio SJ Musumeci <tra...@sp...> wrote:
> >
> > You can optionally deploy it or patch the build to install to a
> > different location / filename.
> >
> > This is what I was getting at prior. The library is not designed to be
> > used this way so without upstreaming some changing that make it easier
> > to do so you'll have to maintain some part of the setup.
> >
> > My biggest problem with embedding libfuse3 was the build system simply
> > not working on older platforms and getting that replaced or officially
> > supporting multiple systems doesn't seem a reasonable ask.
> >
> > On 10/1/2019 7:31 AM, Cyril Cyrov wrote:
> > > Actually, deploying `libfuse3.so` won't be enough, deploying
> > > `fusermount3` is also necessary (+ building libfuse with `-D
> > > FUSERMOUNT_DIR=.....`)? Isn't this some kind of a security issue
> > > (deploying fusermount3)?
> > >
> > > On Tue, Oct 1, 2019 at 1:53 PM Cyril Cyrov <cyr...@gm...> wrote:
> > >> Hi,
> > >>
> > >> Here's an introduction for this thread:
> > >> https://github.com/libfuse/libfuse/issues/460
> > >>
> > >> Long story short:
> > >> Q: How can I support both libfuse2 and libfuse3 in order to make my
> > >> app work on more Linux distos?
> > >> A: You don't need to do that.
> > >>
> > >> So, continuing the discussion here.
> > >>
> > >> ---
> > >>
> > >> My misunderstanding comes from the fact, that I though there are two
> > >> different kernel modules for the two versions and that libfuse3 can
> > >> only work on Linux distros, which do have `fuse3` package installed
> > >> (and these distros are just a few). This misunderstanding was also
> > >> supported by the fact, that libfuse3 needs fusermount3 in order to
> > >> create a mountpoint.
> > >>
> > >> Another miscommunication occurred by the different interpretation of
> > >> "patching the fuse implementation" and "embedding" fuse.
> > >>
> > >> We do deploy a libfuse shared object with our application. So, this is
> > >> not an issue at all.
> > >>
> > >> My concern was - can I use and deploy libfuse3 on older Linux distros,
> > >> like CentOS 6, for example?
> > >>
> > >> What confuses me further is that I cannot find any matching between
> > >> libfuse versions and kernel versions, explaining which libfuse version
> > >> is compatible with which kernel versions.
> > >>
> > >> ---
> > >>
> > >> @trapexit
> > >>> Then you'll have to deal with the distro's support
> > >> By "avoid patching the fuse implementation" I didn't mean I don't want
> > >> to deploy fuse build, I just misunderstood you and thought that you
> > >> suggest actually making some source patch in order to "merge" them
> > >> somehow. Sorry for the misleading.
> > >>
> > >> ---
> > >>
> > >> @Nikratio:
> > >>> "Why don't you ship two binaries (one for libfuse2 and one for libfuse3) together with a small wrapper that picks with version to use?"
> > >> This will be necessary only if we don't deploy a build for libfuse, correct?
> > >>
> > >> ---
> > >>
> > >> So, I'll try to wrap things up, please correct me if I'm wrong - appreciated!
> > >>
> > >> We can actually use only libfuse3 and if we deploy it (or statically
> > >> link it in our application) this should work fine all Linux distros,
> > >> which otherwise would work fine with libfuse2. Is that correct?
> > >> Also, is there a way to find out which libfuse3 features depend on
> > >> which Linux kernel, in order to work fine?
> > >>
> > >> Thanks,
> > >> Kiril
> > >
> >
> >
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