Re: [musl] dynlink.c tests

[Farid Zakaria <fmzakari@ucsc.edu>]

Just to be pedantic, few ideas come to mind:
- One could change the symbol count method to only use DT_HASH and it
would succeed until GCC removed it ;)
- The order of resolution for dependencies
- $ORIGIN replacement

I am very appreciative of the codebase.
I'm going through it at the moment "stripping it down" a bit to be for
x86-64 and adding some comments to help me better understand the
process.
I was going to look at whether I can take on a C++ standard as a
dependency as well.

If you are interested in my fork + what I'm hoping to accomplish,
please reach out.

Thank you Rich.

On Mon, Oct 23, 2023 at 10:57 AM Rich Felker <dalias@libc.org> wrote:
>
> On Mon, Oct 23, 2023 at 10:08:41AM -0700, Farid Zakaria wrote:
> > Sorry for the late reply Rich.
> >
> > That's what my current plan of attack is but I was wondering if the
> > musl codebase itself has such a test suite already
> > (something similar to the libc test suite)
> >
> > How do dynlink authors validate they haven't broken any edge cases in
> > program loading?
> > (i.e. such as DT_GNU_HASH etc..)
>
> Generally this code has almost zero churn, and is expected to be that
> way. Your example of gnu hash for example is a pure mathematical
> function that never has any reason to be changed.
>
> On top of that, none of this is code that dynamically succeeds or
> fails based on any complex runtime condition. For the most part,
> either it does the right thing or it doesn't, and if it doesn't,
> nothing would load.
>
> This doesn't mean testability is unwanted, just that this code is
> rather low priority for testing compared to things with a lot more
> dynamic corner cases.
>
> Rich
>
>
> > On Fri, Oct 20, 2023 at 5:00 PM Rich Felker <dalias@libc.org> wrote:
> > >
> > > On Fri, Oct 20, 2023 at 11:18:44AM -0700, Farid Zakaria wrote:
> > > > What's the best way to test dynlink.c ?
> > > > I'm making some small changes (actually just simplifying it by
> > > > removing some code for unneeded arch like DL_FDPIC) but would like to
> > > > make sure I didn't bork anything.
> > > >
> > > > I found https://wiki.musl-libc.org/writing-tests but that seems
> > > > focused strictly on the libc itself.
> > > > Is there a dynamic-loader test suite anyone is familiar with ?
> > >
> > > The general strategy I would use would be to setup recipes to build
> > > binaries/shared libraries that make use of particular dynamic linking
> > > features, then load/execute them in ways that assert that the relevant
> > > feature operated as expected.
> > >
> > > Rich