Re: What's cooking in git.git (Oct 2021, #02; Wed, 6)

> On Wed, Oct 06, 2021 at 10:24:40PM -0400, Jeff King wrote:
>
>> On Wed, Oct 06, 2021 at 05:24:14PM -0700, Junio C Hamano wrote:
>> 
>> > * tb/repack-write-midx (2021-10-01) 9 commits
>> >   (merged to 'next' on 2021-10-06 at ccdd5aaf2a)
>> >  + builtin/repack.c: pass `--refs-snapshot` when writing bitmaps
>> >  + builtin/repack.c: make largest pack preferred
>> >  + builtin/repack.c: support writing a MIDX while repacking
>> >  + builtin/repack.c: extract showing progress to a variable
>> >  + builtin/repack.c: rename variables that deal with non-kept packs
>> >  + builtin/repack.c: keep track of existing packs unconditionally
>> >  + midx: preliminary support for `--refs-snapshot`
>> >  + builtin/multi-pack-index.c: support `--stdin-packs` mode
>> >  + midx: expose `write_midx_file_only()` publicly
>> > 
>> >  "git repack" has been taught to generate multi-pack reachability
>> >  bitmaps.
>> > 
>> >  Will merge to 'master'.
>> 
>> Sorry not to catch this before it hit 'next', but there's a small leak
>> in the test helper. This patch can go on top to fix it.
>
> The reason for that is that I didn't find it by inspection; I've started
> running my personal builds through coverity. It wasn't too bad to set up
> with a GitHub Action, like so:
>
> ---
>  .github/workflows/coverity.yml | 35 ++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
>  create mode 100644 .github/workflows/coverity.yml
>
> diff --git a/.github/workflows/coverity.yml b/.github/workflows/coverity.yml
> new file mode 100644
> index 0000000000..bfd4dff275
> --- /dev/null
> +++ b/.github/workflows/coverity.yml
> @@ -0,0 +1,35 @@
> +name: coverity-scan
> +on: push
> +
> +jobs:
> +  latest:
> +    runs-on: ubuntu-latest
> +    steps:
> +      - uses: actions/checkout@v2
> +      - run: ci/install-dependencies.sh
> +      - name: Download Coverity Build Tool
> +        run: |
> +          wget -q https://scan.coverity.com/download/linux64 --post-data "token=$TOKEN&project=peff/git" -O cov-analysis-linux64.tar.gz

> +          mkdir cov-analysis-linux64
> +          tar xzf cov-analysis-linux64.tar.gz --strip 1 -C cov-analysis-linux64
> +        env:
> +          TOKEN: ${{ secrets.COVERITY_SCAN_TOKEN }}
> +
> +      - name: Build with cov-build
> +        run: |
> +          export PATH=$(pwd)/cov-analysis-linux64/bin:$PATH
> +          cov-build --dir cov-int make
> +
> +      - name: Submit the result to Coverity Scan
> +        run: |
> +          tar czvf git.tgz cov-int
> +          curl \

> +            --form project=peff/git \
> +            --form token=$TOKEN \
> +            --form email=peff@peff.net \
> +            --form file=@git.tgz \
> +            --form version=$(git rev-parse HEAD) \
> +            --form description="$(./git version)" \
> +            https://scan.coverity.com/builds?project=peff/git
> +        env:
> +          TOKEN: ${{ secrets.COVERITY_SCAN_TOKEN }}
>
> Is there interest in having something like this in the main repo? We'd
> need to tweak some values:

>   - any repo which wants to use this has to set up the secret token
>     (COVERITY_SCAN_TOKEN here). That involves creating a coverity
>     account, and then setting the token in the GitHub web interface.
>     Presumably we'd just bail immediately if that token isn't set, so
>     forks aside from git/git would have to enable it independently.

>   - likewise it needs the email address for the coverity account. That
>     could probably be set in the environment, too.
>
>   - we'd probably want to only run it for integration branches, since
>     coverity sets some limits on how often it runs. This could probably
>     be set in another environment variable, so people could tweak it for
>     their forks if they wanted to (or we could use the ci-config hacks,
>     but I put those together mostly because these environment variables
>     didn't exist back then; I suspect we could switch off of them now).
>
> There are tons of existing warnings, many of which are false positives.
> But it keeps track of which problems are new, and emails out a summary
> of only the new ones (which is how I saw the leak here, which just hit
> next). I don't care all that much about leaks here (we have other
> techniques for finding them), but when Stefan used to do regular
> coverity builds in the past, it routinely found useful errors.
>
> If we had it running on git/git, it's possible for people to subscribe
> to those notifications (or view them on the site; both require the
> people to have coverity accounts, but they're free).
>
> Thoughts?