[PATCH] .github/workflows: add coverity action

[PATCH] .github/workflows: add coverity action

[Taylor Blau]

Coverity is a static analysis tool that detects and generates reports on
various security and code quality issues.

It is particularly useful when diagnosing memory safety issues which may
be used as part of exploiting a security vulnerability.

Coverity's website provides a service accepts "builds" (which is more or
less the collection of '*.o' files generated during a standard build
with "make") as input and generates reports as output. In order to
generate a report, we have to first compile Git and then upload the
build archive to Coverity.

This Action generates and uploads a build archive to Coverity when a
GitHub repository has configured the "COVERITY_SCAN_EMAIL" and
"COVERITY_SCAN_TOKEN" repository secrets, respectively. This enables
Coverity to automatically report on new changes pushed to 'master', as
well as any newly created tags.

A couple of implementation notes:

  - In order to successfully build 'git', we (ab-)use the
    ci/install-dependencies.sh script by faking in some of the
    environment variables to take on values specific to the main.yml
    workflow file in order to install the correct set of dependencies.

  - We could upload the build archive to Coverity directly with a
    straightforward curl request. But using the vapier/coverity-scan
    Action comes with some additional niceties, such as caching the
    (rather large) Coverity tool download between runs.

If the repository is missing either of the two secret tokens mentioned
earlier, this Action is a no-op.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 .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..26b9145d9e
--- /dev/null
+++ b/.github/workflows/coverity.yml
@@ -0,0 +1,35 @@
+name: Coverity
+
+on:
+  push:
+    branches:
+      - master
+    tags:
+      - '*'
+
+jobs:
+  coverity:
+    runs-on: ubuntu-latest
+    env:
+      HAVE_COVERITY_TOKEN: ${{ secrets.COVERITY_SCAN_EMAIL != '' && secrets.COVERITY_SCAN_TOKEN != '' }}
+    steps:
+      - id: check-coverity
+        name: check whether Coverity token is configured
+        run: |
+          echo "enabled=$HAVE_COVERITY_TOKEN" >>$GITHUB_OUTPUT
+      - uses: actions/checkout@v3
+        if: steps.check-coverity.outputs.enabled == 'true'
+      - run: ci/install-dependencies.sh
+        env:
+          CC: gcc
+          CC_PACKAGE: gcc-9
+          jobname: linux-gcc-default
+          runs_on_pool: ubuntu-latest
+        if: steps.check-coverity.outputs.enabled == 'true'
+      - uses: vapier/coverity-scan-action@v1
+        if: steps.check-coverity.outputs.enabled == 'true'
+        with:
+          email: ${{ secrets.COVERITY_SCAN_EMAIL }}
+          token: ${{ secrets.COVERITY_SCAN_TOKEN }}
+          command: make -j8
+
-- 
2.42.0.15.geed1e1a32a

Re: [PATCH] .github/workflows: add coverity action

[Jeff King]

On Mon, Aug 21, 2023 at 11:34:32PM -0400, Taylor Blau wrote:

> Coverity is a static analysis tool that detects and generates reports on
> various security and code quality issues.
> 
> It is particularly useful when diagnosing memory safety issues which may
> be used as part of exploiting a security vulnerability.

I've been running a variant of this on my private repo for the last year
or two. The biggest issue IMHO is that we don't have a good way to
surface problems publicly. The CI "passes" in the sense that the build
is uploaded to coverity, but the interesting bit is whether any new
defects were found (because there are a ton of existing false positives
that I haven't figured out how to silence). So my flow is something
like:

  1. Push to my fork.

  2. Eventually get an email that says "N new defects found".

  3. If N > 0, log into the coverity site and look at them.

What's the plan for adding this to the main git.git repo? Is it to run
on Junio's tree, and then have interested folks sign up for coverity
access and look at it there? If so, how does step 2 work?

Or is it just to have it, so interested parties can do their own
coverity analysis? I'd be happy enough with that, as I am carrying a
similar patch locally.

> Coverity's website provides a service accepts "builds" (which is more or
> less the collection of '*.o' files generated during a standard build
> with "make") as input and generates reports as output. In order to
> generate a report, we have to first compile Git and then upload the
> build archive to Coverity.

I don't think this is quite right. You run a build with their
"cov-build" wrapper, which does some magic. It _does_ invoke the actual
compiler, but does some extra magic, too (I don't know the details, but
it is running cov-translate and cov-emit on the actual source file).

This maybe seems like nit-picking, but it will play into some questions
I have on the patch itself.

>   - We could upload the build archive to Coverity directly with a
>     straightforward curl request. But using the vapier/coverity-scan
>     Action comes with some additional niceties, such as caching the
>     (rather large) Coverity tool download between runs.

Yeah, that is a nice bonus over what I've been using. The tool download
is 800MB!

> diff --git a/.github/workflows/coverity.yml b/.github/workflows/coverity.yml
> new file mode 100644
> index 0000000000..26b9145d9e
> --- /dev/null
> +++ b/.github/workflows/coverity.yml
> @@ -0,0 +1,35 @@
> +name: Coverity
> +
> +on:
> +  push:
> +    branches:
> +      - master
> +    tags:
> +      - '*'

It's probably a good idea not to run this against every single topic
branch. But it's nice if we can catch bugs _before_ they hit master.
Since this isn't a blocking CI job, that's aspirational (it depends on
somebody looking at the results and patching in a timely manner). But I
routinely do my runs against "next" (actually an integration branch that
I base on "next") and investigate the results within a day or two.

Running against "seen" might be even better (though personally I usually
avoid looking at it too closely, as sometimes it has too much of other
people's broken stuff. I have plenty of my own).

I'm not sure what workflow you're envisioning here.

> +jobs:
> +  coverity:
> +    runs-on: ubuntu-latest
> +    env:
> +      HAVE_COVERITY_TOKEN: ${{ secrets.COVERITY_SCAN_EMAIL != '' && secrets.COVERITY_SCAN_TOKEN != '' }}
> +    steps:
> +      - id: check-coverity
> +        name: check whether Coverity token is configured
> +        run: |
> +          echo "enabled=$HAVE_COVERITY_TOKEN" >>$GITHUB_OUTPUT

This check-coverity step is good, as obviously most people's forks won't
be set up to run it. It is a shame we'll have to kick off an actions vm
just to echo "enabled=0". Is there any way to embed that logic directly
in the yaml (I won't be surprised if the answer is "no"; I've been
looking for years for something similar for check-config in the main
workflow).

> +      - uses: actions/checkout@v3
> +        if: steps.check-coverity.outputs.enabled == 'true'
> +      - run: ci/install-dependencies.sh
> +        env:
> +          CC: gcc
> +          CC_PACKAGE: gcc-9
> +          jobname: linux-gcc-default
> +          runs_on_pool: ubuntu-latest
> +        if: steps.check-coverity.outputs.enabled == 'true'

In the workflow file I've been using, I didn't need to do any of this CC
magic. I do run install-dependencies, but it seems to work fine without
extra variables. I do set runs_on_pool=ubuntu-latest in mine. Maybe that
matters (it does hit UBUNTU_COMMON_PKGS)?

> +      - uses: vapier/coverity-scan-action@v1
> +        if: steps.check-coverity.outputs.enabled == 'true'
> +        with:
> +          email: ${{ secrets.COVERITY_SCAN_EMAIL }}
> +          token: ${{ secrets.COVERITY_SCAN_TOKEN }}
> +          command: make -j8

OK, this is presumably doing the cov-build stuff behind the scenes, as
well as the curl upload. In my file, we have to feed a "project" field.
I guess the action just figures this out from whichever repo we're
using. Do GitHub repo names always correspond to coverity project names?
(It does seem kind of superfluous; I think the SCAN_TOKEN is unique to
the project).

-Peff

Re: [PATCH] .github/workflows: add coverity action

[Jeff King]

On Fri, Aug 25, 2023 at 05:32:01PM -0400, Jeff King wrote:

> > Coverity's website provides a service accepts "builds" (which is more or
> > less the collection of '*.o' files generated during a standard build
> > with "make") as input and generates reports as output. In order to
> > generate a report, we have to first compile Git and then upload the
> > build archive to Coverity.
> 
> I don't think this is quite right. You run a build with their
> "cov-build" wrapper, which does some magic. It _does_ invoke the actual
> compiler, but does some extra magic, too (I don't know the details, but
> it is running cov-translate and cov-emit on the actual source file).
> 
> This maybe seems like nit-picking, but it will play into some questions
> I have on the patch itself.

I guess I never actually asked those questions, but they were: why are
you asking for some specific version of gcc since we don't really care
much about the actual compiler.

But I think you don't care about the compiler version; you were just
trying to feed enough data to install-dependencies to get it to run.

-Peff

Re: [PATCH] .github/workflows: add coverity action

[Johannes Schindelin]

Hi Taylor,

On Mon, 21 Aug 2023, Taylor Blau wrote:

> diff --git a/.github/workflows/coverity.yml b/.github/workflows/coverity.yml
> new file mode 100644
> index 0000000000..26b9145d9e
> --- /dev/null
> +++ b/.github/workflows/coverity.yml
> @@ -0,0 +1,35 @@
> +name: Coverity
> +
> +on:
> +  push:
> +    branches:
> +      - master
> +    tags:
> +      - '*'

I would consider it too late to do a Coverity analysis when the version
is already tagged. Therefore, I would like to see this `tags: *' part go.

And I agree with Peff that we should activate this build for `next`, too.
And for good measure for `maint` (and maybe `maint-*`, although those
branches are typically not pushed to `git/git`).

> +
> +jobs:
> +  coverity:
> +    runs-on: ubuntu-latest
> +    env:
> +      HAVE_COVERITY_TOKEN: ${{ secrets.COVERITY_SCAN_EMAIL != '' && secrets.COVERITY_SCAN_TOKEN != '' }}
> +    steps:
> +      - id: check-coverity
> +        name: check whether Coverity token is configured
> +        run: |
> +          echo "enabled=$HAVE_COVERITY_TOKEN" >>$GITHUB_OUTPUT

The canonical output for a step that has no other outputs is called
`result`. That output name is handled by linters such as
https://rhysd.github.io/actionlint/, too, in contrast to outputs with
different names that may be set in a free-form `run:` step that is
impossible to parse by `actionlint`.

But I see a bigger problem: Contrary to what the commit message claims,
the design makes this workflow far from a no-op: There will always be the
need for a VM to be spun up, to receive the orchestration script, to
download the necessary Actions (in this instance,
`vapier/coverity-scan-action`), only to check environment variables, see
that actually nothing needs to be done, update the job's and the run's
status (claiming "success" even if nothing was sent to Coverity) and then
shut down.

We discussed this in the past, as it is a great waste of resources (even
if other people pay for it, it still costs money [*1*] and electricity),
and for some of us even more relevant: it is a great waste of time because
when you are already waiting for 20 queued jobs to be picked up, having to
wait for the next build agent to become available only to spend, I don't
know, half a minute (wall clock time)? on getting this workflow run
queued, the next build agent to become available, the job to be set up,
the first step to be run, the others to be skipped, and then to wrap it
all up by updating the run as completed. I would not fault anyone for
being frustrated with this.

Therefore, I would strongly suggest looking for alternative ways to skip
this workflow run, before applying this patch.

I see these viable alternatives, all pulling the `if:` directive from the
step level to the job level, just like the `l10n.yml` workflow does [*2*],
to avoid even starting the job unless really needed:

- Limit it to the primary repository, `git/git`:

	if: github.event.repository.fork == false

  This is what Git for Windows does in the build that validates the
  revision to use in the `git-for-windows/setup-git-for-windows-sdk`
  Action that is used in Git's CI runs to build and test Git on Windows:
  https://github.com/git-for-windows/git-sdk-64/blob/894191270a78/.github/workflows/ci-artifacts.yml#L14

  While this still clutters the list of workflow runs with plenty of
  skipped runs (see https://github.com/git/git/actions/workflows/l10n.yml
  for an example how this looks), at least it avoids wasting a build agent
  on essentially only checking for the presence of two secrets.

  Developers wishing to run this workflow in their fork could always
  create a branch, edit the workflow to remove this `if:` directive, and
  push the branch to their fork.

- Limit it to `git/git` explicitly, by name:

	if: github.event.repository.owner.login == 'git'

  This is how we run the `vs-build`/`vs-test` combo only in the
  `git-for-windows` fork:
  https://github.com/git/git/blob/v2.42.0/.github/workflows/main.yml#L150

  The advantage here is that it would be slightly more obvious what we are
  doing here than checking `fork == false`, as the org name is mentioned
  explicitly.

- Limit it to `git/git` but also allow it to be triggered manually:

	if: github.event.repository.fork == false || github.event_name == 'workflow_dispatch'

  This is what Git for Windows does in the test verifying that it works in
  the "Nano Server" container image that allows for kind of a minimal
  Windows system to be run via Docker:
  https://github.com/git-for-windows/git-sdk-64/blob/894191270a78/.github/workflows/nano-server.yml#L7

  The advantage of allowing the workflow to be triggered via a
  `workflow_dispatch` is that developers wishing to run this workflow in
  their fork would not need to edit the GitHub workflow but could run it
  unmodified. For details, see
  https://docs.github.com/en/actions/using-workflows/manually-running-a-workflow

- Limit it by repository "topics" (think: "repository tags"):

	if: contains(github.event.repository.topics, 'has-coverity-secrets')

  On GitHub, every repository can be annotated with "topics", i.e. a list
  of labels (which in other scenarios would be called "tags"). These
  topics can be seen by the GitHub workflow run, _before_ even starting a
  job, via the `github.event.repository` attribute.

  This is how InnoSetup does it:
  https://github.com/jrsoftware/issrc/blob/main/.github/workflows/build.yml#L12
  The primary repository does not have the secrets required to run this
  workflow, and hence does not have the "has-issrc-build-env" topic as
  can be seen here: https://github.com/jrsoftware/issrc (look below the
  "About" section on the right side, where you see the topics "installer"
  and "inno-setup"). My personal fork does have them secrets, and the
  topic "has-issrc-build-env" says as much: https://github.com/dscho/issrc

  The advantage of this solution is that it is very easy to "turn on and
  off" the workflow on a repository level, simply by adding or removing
  the "has-coverity-secrets" topic. See:
  https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/classifying-your-repository-with-topics

  The downside is that this method is somewhat unintuitive and needs the
  developer to read documentation (*shudder*) to know what they need to
  do.

I have no strong preference as long as the job is skipped whenever the
Coverity build (read: the `coverity` GitHub workflow run) should be
skipped.

> +      - uses: actions/checkout@v3
> +        if: steps.check-coverity.outputs.enabled == 'true'
> +      - run: ci/install-dependencies.sh
> +        env:
> +          CC: gcc
> +          CC_PACKAGE: gcc-9
> +          jobname: linux-gcc-default

How about modifying `ci/install-dependencies.sh` to introduce a new job
name, `coverity`, that is handled like `linux-gcc-default`? I.e. something
like this:

-- snip --
diff --git a/ci/install-dependencies.sh b/ci/install-dependencies.sh
index 107757a1fea..e6a894e507d 100755
--- a/ci/install-dependencies.sh
+++ b/ci/install-dependencies.sh
@@ -74,7 +74,7 @@ Documentation)
 	test -n "$ALREADY_HAVE_ASCIIDOCTOR" ||
 	sudo gem install --version 1.5.8 asciidoctor
 	;;
-linux-gcc-default)
+linux-gcc-default|coverity)
 	sudo apt-get -q update
 	sudo apt-get -q -y install $UBUNTU_COMMON_PKGS
 	;;
diff --git a/ci/lib.sh b/ci/lib.sh
index 1b0cc2b57db..7a196aa0d17 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -227,7 +227,7 @@ export SKIP_DASHED_BUILT_INS=YesPlease

 case "$runs_on_pool" in
 ubuntu-latest)
-	if test "$jobname" = "linux-gcc-default"
+	if test "$jobname" = "linux-gcc-default" ||  test "$jobname" = "coverity"
 	then
 		break
 	fi
-- snap --

That would be a lot cleaner and would also allow for Coverity-specific
things in this step that won't affect `linux-gcc-default` at the same
time.

> +          runs_on_pool: ubuntu-latest
> +        if: steps.check-coverity.outputs.enabled == 'true'
> +      - uses: vapier/coverity-scan-action@v1

In contrast to the other Actions we use in Git, this one is neither
provided by GitHub nor by the Git (or Git for Windows) project [*3*].

The recommended way to handle such third-party Actions is to pin them by
full length commit SHA:
https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-third-party-actions

This is particularly important because we're passing secret values to that
Action.

> +        if: steps.check-coverity.outputs.enabled == 'true'
> +        with:
> +          email: ${{ secrets.COVERITY_SCAN_EMAIL }}
> +          token: ${{ secrets.COVERITY_SCAN_TOKEN }}
> +          command: make -j8
> +

The commit message would make for a fine place to describe the role of
these `COVERITY_SCAN_*` secrets, how to obtain them, and how to configure
them (i.e. providing a link to
https://docs.github.com/en/actions/security-guides/encrypted-secrets#creating-encrypted-secrets-for-a-repository).

The reason I am suggesting that is that many a time, I have authored
commits like this one, only to puzzle about the exact steps to configure
the the thing properly when I needed it six months later, and regretting
dearly not having had the foresight to help my future self while writing
the commit message.

Another important issue that should be discussed in the commit message is
the matter of Coverity's false positives. I regularly dread going through
the new reports in Coverity (I am doing this for git-for-windows) because
of the many falsely pointed out "buffer overruns" when working e.g. with
`strvec` where Coverity assumes that its `empty_strvec` is ever written
to.

In Git for Windows, I have not had any luck with suppressing these false
reports. For what it's worth, this is the "model file" I am currently
using:

-- snip --
/* modelfile for git */

char strbuf_slopbuf[64];

void *malloc(size_t);
void *calloc(size_t, size_t);
void *realloc(void *, size_t);
void free(void *);

void *xrealloc(void *ptr, size_t size)
{
	void *ret = realloc(ptr, size);
	if (!ret) __coverity_panic__();
	return ret;
}

void *xmalloc(size_t size)
{
	void *mem = malloc(size);
	if (!mem) __coverity_panic__();
	return mem;
}

void xcalloc(size_t num, size_t size)
{
	void *ret = calloc(num, size);
	if (!ret)  __coverity_panic__();
	return ret;
}

void usage(const char *err) {
  __coverity_panic__();
}

void usagef(const char *err, ...) {
  __coverity_panic__();
}

void die(const char *err, ...)  {
  __coverity_panic__();
}

void die_errno(const char *err, ...) {
  __coverity_panic__();
}

void BUG_fl(const char *file, int line, const char *fmt, ...) {
  __coverity_panic__();
}

struct strbuf {
	size_t alloc;
	size_t len;
	char *buf;
};

void strbuf_setlen(struct strbuf *sb, size_t len)
{
        sb->len = len;
	sb->buf[len] = '\0';
}

void strbuf_grow(struct strbuf *sb, size_t amount);

void *memcpy(void *dest, const void *src, size_t n);

void strbuf_add(struct strbuf *sb, const void *data, size_t len)
{
	strbuf_grow(sb, len);
	memcpy(sb->buf + sb->len, data, len);
	sb->len = len;
	sb->buf[len] = '\0';
}

void *memmove(void *dest, const void *src, size_t n);

void strbuf_splice(struct strbuf *sb, size_t pos, size_t len,
				   const void *data, size_t dlen)
{
	if (pos > sb->len)
		die("`pos' is too far after the end of the buffer");
	if (pos + len > sb->len)
		die("`pos + len' is too far after the end of the buffer");

	if (dlen >= len)
		strbuf_grow(sb, dlen - len);
	memmove(sb->buf + pos + dlen,
			sb->buf + pos + len,
			sb->len - pos - len);
	memcpy(sb->buf + pos, data, dlen);
	sb->len = sb->len + dlen - len;
	sb->buf[sb->len + dlen - len] = '\0';
}
-- snap --

It is getting a bit ridiculous at this point, the size of it and the
meager benefit it reaps. But it is better than nothing, I guess.

The reason I would really like to see an extensive discussion about this
in the commit message is that this place would be _the_ most logical
habitat for such a description, to help developers who want to set up
their own Coverity coverage (either in their own Git fork, or even in a
separate project) trying to learn from the Git project.

Ciao,
Johannes

Footnote *1*: In case it was unclear: Build agents are essentially virtual
machines. Those virtual machines are destroyed after every run, and
recreated to a pristine state before picking up the next job. To avoid
having to wait for a virtual machine to be created whenever a job needs to
be run, there is a pool of virtual machines ready to run. There have been
times when we ran so many jobs in the Git project that we drained that
pool and had to wait, painfully, for the virtual machines to be created
which, let me tell you, is not a matter of a mere couple of seconds.

This complexity is reflected in the pricing you can see at
https://docs.github.com/en/billing/managing-billing-for-github-actions/about-billing-for-github-actions

Just to put things into perspective: In our security work, we have to run
our GitHub workflow in a private repository, where GitHub Actions are not
provided free of cost by GitHub. We have a very nice donation from GitHub
in the form of 50,000 build minutes we can use every month. If we spent
all of those minutes running on Linux (i.e. the cheapest option), GitHub
would essentially donate $400 to us. That's what we usually spend in a
matter of days preparing for security releases: The workflow run to
validate v2.39.3, for example, while taking "only" 36 minutes and 1 second
wall clock time, used up over 12 hours of those 50,000 build minutes, and
every time we iterated, we pushed 11 branches and 11 tags. Three
iterations in, we were out of build minutes.

All this is to say: We, the Git project, are not exactly cautious when it
comes to spending GitHub Actions build minutes. I really would love to see
us all to become a lot more mindful on this matter.

Footnote *2*:
https://github.com/git/git/blob/v2.42.0/.github/workflows/l10n.yml#L13

Footnote *3*: We do already use a third-party Action in `l10n.yml`:
`mshick/add-pr-comment@v1`. As you can verify easily, this is not pinned
by full length commit SHA. But then, this step only gets the
`GITHUB_TOKEN` secret, which only has the permission to write to the Pull
Request (i.e. add a comment), not to write to the repository.

Still, we will probably want to pin that Action at some stage, better safe
'n sorry. #leftoverbits

Re: [PATCH] .github/workflows: add coverity action

[Jeff King]

On Tue, Aug 29, 2023 at 10:18:24AM +0200, Johannes Schindelin wrote:

> - Limit it by repository "topics" (think: "repository tags"):
> 
> 	if: contains(github.event.repository.topics, 'has-coverity-secrets')

FWIW, I like this approach the most. As you note, it's not exactly
obvious to discover, but I think it is the most flexible. And setting up
Coverity runs already requires a lot of non-obvious steps (like creating
an account with them and getting a token to paste into the GitHub
secrets area).

My gut feeling is that we should be able to do something with env
variables to avoid the (ab)use of repository tags, but when I looked
into this in the past, it wasn't possible.  However, poking at it again
now, it seems that the "vars" context (but not "secrets") is available
to "jobs.*.if". I'm not sure if I missed before, or if that's a new
feature since the last time I checked.

At any rate, it seems to work to do:

  if: vars.ENABLE_COVERITY != ''

or even make COVERITY_SCAN_EMAIL a "var" instead of a "secret", and use
that. Likewise, I think we could do:

  if: contains(vars.COVERITY_BRANCHES, github.ref_name)

to allow individual repositories to do their own branch selection (that
is matching by substring, which is probably good enough, but if you want
to get fancy, I think we can use fromJSON to interpret the contents of
the variable).

(I had mostly looked into this in the context of branch selection for
our ci-config job, and I think we could do something similar there).

-Peff

Re: [PATCH] .github/workflows: add coverity action

[Johannes Schindelin]

Hi Peff,

On Tue, 29 Aug 2023, Jeff King wrote:

> On Tue, Aug 29, 2023 at 10:18:24AM +0200, Johannes Schindelin wrote:
>
> > - Limit it by repository "topics" (think: "repository tags"):
> >
> > 	if: contains(github.event.repository.topics, 'has-coverity-secrets')
>
> FWIW, I like this approach the most. [...]
>
> My gut feeling is that we should be able to do something with env
> variables [...]

Environment variables need an environment, i.e. a running build agent.
That's why they aren't available in our use case, but only inside a step
(which is too late for our purposes).

I am unsure why secrets aren't available in job-level `if:` expressions,
but they aren't, and that's that, for now.

> [...] it seems that the "vars" context (but not "secrets") is available
> to "jobs.*.if". I'm not sure if I missed before, or if that's a new
> feature since the last time I checked.

I had missed that, too. It was announced here:
https://github.blog/2023-01-10-introducing-required-workflows-and-configuration-variables-to-github-actions/#configuration-variables
(I must have glanced over that post when I saw it because it talked about
required workflows, which are currently irrelevant to my interests).

FWIW the feature is documented here:
https://docs.github.com/en/actions/learn-github-actions/variables

And
https://docs.github.com/en/actions/learn-github-actions/variables#using-the-vars-context-to-access-configuration-variable-values
specifically says:

	Configuration variables can be accessed across the workflow using
	`vars` context.

I.e. it suggests that the context can be used even in the `run-name`
attribute of any workflow. Nice.

FWIW I was unable to deduce any authoritative information as to where the
`secrets` context can be accessed from
https://docs.github.com/en/actions/learn-github-actions/contexts#secrets-context,
but I must assume that access to that context is highly restricted and
probably cannot be used outside the `steps:` attribute, explaining why a
job-level (and in my previous tests, even step-level) `if:` condition
cannot access them.

> (I had mostly looked into this in the context of branch selection for
> our ci-config job, and I think we could do something similar there).

FWIW I concur.

Ciao,
Johannes

Re: [PATCH] .github/workflows: add coverity action

[Jeff King]

On Wed, Aug 30, 2023 at 10:07:35AM +0200, Johannes Schindelin wrote:

> > My gut feeling is that we should be able to do something with env
> > variables [...]
> 
> Environment variables need an environment, i.e. a running build agent.
> That's why they aren't available in our use case, but only inside a step
> (which is too late for our purposes).

Yeah, sorry I was a bit loose with my language. I meant "variables set
from the GitHub UI that are often used as env variables". :)

> > [...] it seems that the "vars" context (but not "secrets") is available
> > to "jobs.*.if". I'm not sure if I missed before, or if that's a new
> > feature since the last time I checked.
> 
> I had missed that, too. It was announced here:
> https://github.blog/2023-01-10-introducing-required-workflows-and-configuration-variables-to-github-actions/#configuration-variables
> (I must have glanced over that post when I saw it because it talked about
> required workflows, which are currently irrelevant to my interests).

Yeah, I found that, too (after sending my email). So it looks like this
is a good, supported path for going forward.

I have a working patch that can replace the ci/config/allow-ref script.
We can't totally ditch the "config" job with it, as there are other
things it does, but it's possible those can be migrated, too. IMHO the
allow-ref one is the _most_ important, though, because it addresses the
case of "everything should be skipped".  Taking that from spinning up
one VM per ref to zero is very good.

I'll post that patch later today.

> FWIW I was unable to deduce any authoritative information as to where the
> `secrets` context can be accessed from
> https://docs.github.com/en/actions/learn-github-actions/contexts#secrets-context,
> but I must assume that access to that context is highly restricted and
> probably cannot be used outside the `steps:` attribute, explaining why a
> job-level (and in my previous tests, even step-level) `if:` condition
> cannot access them.

I found the "vars" context through this table:

  https://docs.github.com/en/actions/learn-github-actions/contexts#context-availability

which does show where "secrets" is available.

-Peff

[PATCH v2] .github/workflows: add coverity action

[Taylor Blau]

Coverity is a static analysis tool that detects and generates reports on
various security and code quality issues.

It is particularly useful when diagnosing memory safety issues which may
be used as part of exploiting a security vulnerability.

Coverity's website provides a service accepts "builds" (which is the
output of running `cov-build` on your project, which invokes `make` with
additional magic) as input and generates reports as output. In order to
generate a report, we have to first compile Git and then upload the
build archive to Coverity.

This Action generates and uploads a build archive to Coverity when a
GitHub repository has done the following:

- Configured the "COVERITY_SCAN_EMAIL" and "COVERITY_SCAN_TOKEN"
  repository secrets. Tokens are found on the "Project Settings" page at
  [1]. Tokens may be added as repository secrets on GitHub repositories
  by following the guide at [2].

- Enabled Coverity builds by (in addition to the above) creating a
  repository variable called `ENABLE_COVERITY`. Repository variables
  (which are different than secrets) can be added according to the guide
  at [3].

This enables Coverity to automatically report on new changes pushed to
the configured branch set, which is specified via the
`COVERITY_BRANCHES` repository variable.

The implementation is mostly straightforward. Though note that we could
upload the build archive to Coverity directly with a straightforward
curl request. But using the vapier/coverity-scan Action comes with some
additional niceties, such as caching the (rather large) Coverity tool
download between runs.

If the repository does not have the `ENABLE_COVERITY` variable set, or
the list of branches specified by `COVERITY_BRANCHES` does not contain
the branch being pushed to, this Action is a no-op.

[1]: https://scan.coverity.com/projects/NAME?tab=project_settings
[2]: https://docs.github.com/en/actions/security-guides/using-secrets-in-github-actions
[3]: https://docs.github.com/en/actions/learn-github-actions/variables

Helped-by: Jeff King <peff@peff.net>
Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
This fell to the bottom of my queue, but I got back to it today while
doing some ~~spring~~ fall inbox cleaning :-). Thanks Peff and Johannes
for helpful review in the first round. Range-diff is below:

Range-diff against v1:
1:  f74ae75ddb < -:  ---------- .github/workflows: add coverity action
-:  ---------- > 1:  b23951c569 .github/workflows: add coverity action

 .github/workflows/coverity.yml | 22 ++++++++++++++++++++++
 ci/install-dependencies.sh     |  2 +-
 ci/lib.sh                      |  2 +-
 3 files changed, 24 insertions(+), 2 deletions(-)
 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..3ba00b3929
--- /dev/null
+++ b/.github/workflows/coverity.yml
@@ -0,0 +1,22 @@
+name: Coverity
+
+on: [push, pull_request]
+
+jobs:
+  coverity:
+    if: (vars.ENABLE_COVERITY == 'true') &&
+      (vars.COVERITY_BRANCHES == '' ||
+       contains(vars.COVERITY_BRANCHES, github.ref_name) ||
+       contains(vars.COVERITY_BRANCHES, '*'))
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - run: ci/install-dependencies.sh
+        env:
+          jobname: coverity
+      - uses: vapier/coverity-scan-action@cae3c096a2eb21c431961a49375ac17aea2670ce
+        with:
+          email: ${{ secrets.COVERITY_SCAN_EMAIL }}
+          token: ${{ secrets.COVERITY_SCAN_TOKEN }}
+          command: make -j8
+
diff --git a/ci/install-dependencies.sh b/ci/install-dependencies.sh
index 4f407530d3..7e100ee63f 100755
--- a/ci/install-dependencies.sh
+++ b/ci/install-dependencies.sh
@@ -74,7 +74,7 @@ Documentation)
 	test -n "$ALREADY_HAVE_ASCIIDOCTOR" ||
 	sudo gem install --version 1.5.8 asciidoctor
 	;;
-linux-gcc-default)
+linux-gcc-default|coverity)
 	sudo apt-get -q update
 	sudo apt-get -q -y install $UBUNTU_COMMON_PKGS
 	;;
diff --git a/ci/lib.sh b/ci/lib.sh
index 6fbb5bade1..2ad0ae340e 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -227,7 +227,7 @@ export SKIP_DASHED_BUILT_INS=YesPlease

 case "$runs_on_pool" in
 ubuntu-*)
-	if test "$jobname" = "linux-gcc-default"
+	if test "$jobname" = "linux-gcc-default" || test "$jobname" = "coverity"
 	then
 		break
 	fi
--
2.42.0.242.gc844f407a1

Re: [PATCH v2] .github/workflows: add coverity action

[Junio C Hamano]

Taylor Blau <me@ttaylorr.com> writes:

> This fell to the bottom of my queue, but I got back to it today while
> doing some ~~spring~~ fall inbox cleaning :-). Thanks Peff and Johannes
> for helpful review in the first round. Range-diff is below:
>
> Range-diff against v1:
> 1:  f74ae75ddb < -:  ---------- .github/workflows: add coverity action
> -:  ---------- > 1:  b23951c569 .github/workflows: add coverity action

That's a useful range-diff ;-).  Even with --word-diff, range-diff does
not notice that they correspond to each other, without an absurd setting
like --creation-factor=999.

>  .github/workflows/coverity.yml | 22 ++++++++++++++++++++++
>  ci/install-dependencies.sh     |  2 +-
>  ci/lib.sh                      |  2 +-
>  3 files changed, 24 insertions(+), 2 deletions(-)
>  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..3ba00b3929
> --- /dev/null
> +++ b/.github/workflows/coverity.yml
> @@ -0,0 +1,22 @@
> +name: Coverity
> +
> +on: [push, pull_request]

This no longer hardcocdes the condition to master and tagged ones,
as ...

> +jobs:
> +  coverity:
> +    if: (vars.ENABLE_COVERITY == 'true') &&
> +      (vars.COVERITY_BRANCHES == '' ||
> +       contains(vars.COVERITY_BRANCHES, github.ref_name) ||
> +       contains(vars.COVERITY_BRANCHES, '*'))

... this lets you control when to run it via the "vars".  This round
also can act on pull-requests in addition to pushes.

> +    runs-on: ubuntu-latest
> +    steps:
> +      - uses: actions/checkout@v3
> +      - run: ci/install-dependencies.sh
> +        env:
> +          jobname: coverity
> +      - uses: vapier/coverity-scan-action@cae3c096a2eb21c431961a49375ac17aea2670ce
> +        with:
> +          email: ${{ secrets.COVERITY_SCAN_EMAIL }}
> +          token: ${{ secrets.COVERITY_SCAN_TOKEN }}
> +          command: make -j8

And the actual implementation is vastly different by just using a
canned one, which requires less maintenance on our end, which is
nice.

> diff --git a/ci/lib.sh b/ci/lib.sh
> index 6fbb5bade1..2ad0ae340e 100755
> --- a/ci/lib.sh
> +++ b/ci/lib.sh
> @@ -227,7 +227,7 @@ export SKIP_DASHED_BUILT_INS=YesPlease
>
>  case "$runs_on_pool" in
>  ubuntu-*)
> -	if test "$jobname" = "linux-gcc-default"
> +	if test "$jobname" = "linux-gcc-default" || test "$jobname" = "coverity"
>  	then
>  		break
>  	fi

This part is new in this iteration, to avoid further customization
that enables more exotic features, which makes sense.

Re: [PATCH v2] .github/workflows: add coverity action

[Johannes Schindelin]

Hi Taylor,

thank you for continuing your work on this. The timing is a bit
unfortunate, though: As I had not heard back from you in this thread, I
had started work yesterday morning on converting Git for Windows'
corresponding Azure Pipeline to a GitHub workflow as a consequence. I had
to leave some polishing for this morning because the validation that the
workflow actually runs correctly and is versatile enough to address both
the needs of the Git project as well as of the Git for Windows project
took longer than anticipated and revealed a couple of problems on which I
will elaborate below.

On Thu, 21 Sep 2023, Taylor Blau wrote:

> [...] using the vapier/coverity-scan Action comes with some additional
> niceties, such as caching the (rather large) Coverity tool download
> between runs.

While it is true that that Action caches the Coverity Tool, this GitHub
Action comes with a few non-niceties, too, one of them being that it
actually fails to do its job. Looking at
https://github.com/vapier/coverity-scan-action/blob/main/action.yml it can
be very easily verified that `cov-configure` is not called. But as
https://github.com/git-for-windows/git/actions/runs/6267593979/job/17020975444#step:9:12
demonstrates, this command now _needs_ to be called:

	Error:  Could not find file coverity_config.xml in directory D:/a/_temp/cov-analysis/config

	The cov-build.exe command needs a configuration file, generated by
	cov-configure, to know how to capture analysis inputs based on
	compiler invocations and/or scanning the filesystem.
	Examples of running cov-configure:

	cov-configure --cs          Microsoft C# compiler (csc)
	cov-configure --gcc         GNU C/C++ compiler (gcc/g++)
	cov-configure --java        Oracle Java compiler (javac)
	cov-configure --javascript  *.js JavaScript source code
	cov-configure --msvc        Microsoft C/C++ compiler (cl)

	See cov-configure documentation for more information.

I had encountered this issue already in April last year and had addressed
it in https://github.com/git-for-windows/build-extra/commit/cec961d2536c,
so it came as an unwelcome surprise to me that this GitHub Action leaves
this problem unaddressed.

Another issue I ran into: That Action defaults to using the URL-encoded
name of the repository (in our case, `git%2Fgit`) as Coverity project
name. That project does not exist, though, and the GitHub Action therefore
silently assumes an empty MD5 and attempts to extract a tar file that is
actually a text file instead, with the contents "Not found".

Further, when I tried to specify `win64` as this GitHub Action's
`platform` input variable (whose existence suggests that platforms other
than `linux64` are allowed), it totally fell over, trying to untar a
`.zip` file.

For this and for various other reasons detailed in the cover letter of
https://lore.kernel.org/git/pull.1588.git.1695379323.gitgitgadget@gmail.com,
it would appear that unfortunately that GitHub Action won't be helpful
here.

Ciao,
Johannes

Re: [PATCH v2] .github/workflows: add coverity action

[Jeff King]

On Thu, Sep 21, 2023 at 05:53:31PM -0400, Taylor Blau wrote:

> diff --git a/.github/workflows/coverity.yml b/.github/workflows/coverity.yml
> new file mode 100644
> index 0000000000..3ba00b3929
> --- /dev/null
> +++ b/.github/workflows/coverity.yml
> @@ -0,0 +1,22 @@
> +name: Coverity
> +
> +on: [push, pull_request]
> +
> +jobs:
> +  coverity:
> +    if: (vars.ENABLE_COVERITY == 'true') &&
> +      (vars.COVERITY_BRANCHES == '' ||
> +       contains(vars.COVERITY_BRANCHES, github.ref_name) ||
> +       contains(vars.COVERITY_BRANCHES, '*'))

I wonder if we really need this ENABLE_COVERITY flag. It's not _too_
hard to set up, but it feels like we can eliminate a setup step and just
infer it from other variables.  Either:

  1. Treat unset COVERITY_BRANCHES as "do not run". Unlike the CI job,
     there's not much useful signal in running this for every PR. A
     human has to go periodically look at the coverity output and make
     sense of it. So I think it's something that would get run
     periodically (say, on updates of "next") just for one or two
     branches.

  2. Use COVERITY_SCAN_EMAIL as a clue that the feature it is enabled. I
     don't think we can do that as-is because it's a secret, not a var.
     But is there a reason for the EMAIL to be a secret? I don't think
     repository vars are fully public; they're just not hidden as deeply
     as secrets. It seems like the right level of privacy for an email.

> +    runs-on: ubuntu-latest
> +    steps:
> +      - uses: actions/checkout@v3
> +      - run: ci/install-dependencies.sh
> +        env:
> +          jobname: coverity
> +      - uses: vapier/coverity-scan-action@cae3c096a2eb21c431961a49375ac17aea2670ce
> +        with:
> +          email: ${{ secrets.COVERITY_SCAN_EMAIL }}
> +          token: ${{ secrets.COVERITY_SCAN_TOKEN }}
> +          command: make -j8

I ran the action and it worked out of the box for me (I have everything
set up on the coverity side already from my custom workflow), modulo one
hiccup. I initially had COVERITY_SCAN_EMAIL as a var, so the upload
failed, complaining of an empty email.

But much to my surprise, the Action still succeeded. It didn't record
the HTTP result code, so I'm not sure if we could detect this with "curl
--fail-with-body" or if we'd have to scrape the output. It may not be
that big a deal either way, though, since the coverity output really is
useless until a human periodically scans over it (but it would be nice
to know if it was routinely failing; I might not notice if it didn't).

-Peff

Re: [PATCH v2] .github/workflows: add coverity action

[Jeff King]

On Fri, Sep 22, 2023 at 01:09:26PM +0200, Johannes Schindelin wrote:

> While it is true that that Action caches the Coverity Tool, this GitHub
> Action comes with a few non-niceties, too, one of them being that it
> actually fails to do its job. Looking at
> https://github.com/vapier/coverity-scan-action/blob/main/action.yml it can
> be very easily verified that `cov-configure` is not called. But as
> https://github.com/git-for-windows/git/actions/runs/6267593979/job/17020975444#step:9:12
> demonstrates, this command now _needs_ to be called:

Hmm. I have been running Coverity for years without running
cov-configure (using my own workflow), and I just tested Taylor's patch,
which worked fine. I wonder what is different about our setups; maybe it
is only an issue on the Windows version of Coverity?

Or maybe it has to do with the project setup on Coverity's server side,
since we have to provide the project name as part of the tool download
(though I don't know if that is purely for logging/auditing on their
side or if the delivered download is customized in any way).

> Another issue I ran into: That Action defaults to using the URL-encoded
> name of the repository (in our case, `git%2Fgit`) as Coverity project
> name. That project does not exist, though, and the GitHub Action therefore
> silently assumes an empty MD5 and attempts to extract a tar file that is
> actually a text file instead, with the contents "Not found".

It took me a minute to understand what you meant here, since the main
use of the project name is for uploading our tarball. But we also must
provide it (along with the token) just to download their scan software,
so that step failed.

And yes, I agree that the error checking in the Action could be better
(I also mentioned elsewhere in the thread that it did not detect or
report a failed upload). I'm not sure if it is easier to submit a patch
there, or if we are better off just doing it all inline (it is not that
much code either way).

> Further, when I tried to specify `win64` as this GitHub Action's
> `platform` input variable (whose existence suggests that platforms other
> than `linux64` are allowed), it totally fell over, trying to untar a
> `.zip` file.

Hmm, yes, I hadn't really considered running Coverity with different
build configurations. But I guess it needs to run code through the
compiler to do its magic, so you'd want to be able to run it on a
Windows build to hit any platform-specific code.

For general git/git use, I'm not sure if we'd want to run it on multiple
platforms, but I guess your plan would be to share the workflow code
between git/ and git-for-windows/, and use a repo variable to select the
platform for the latter. And for that case we can't rely on an Action
which doesn't support Windows.

I'll take a look at the patches you posted.

-Peff

Re: [PATCH v2] .github/workflows: add coverity action

[Jeff King]

On Sat, Sep 23, 2023 at 02:21:37AM -0400, Jeff King wrote:

> I'll take a look at the patches you posted.

OK, I just read over them. I do think the result is not much more
complicated than using the vapier Action, and it fits our multi-platform
needs a bit better.

I had a few small comments about curl usage, but it mostly looks like a
good direction to me.

-Peff