threads / patch / 57929

patchhook: provide GIT_HOOK for all hooks

Subject: [PATCH] hook: provide GIT_HOOK for all hooks

## tl;dr

7 messages between May 27, 2022 and May 31, 2022. Diffs are folded; open one to read it.

replies: 6people: 3as markdown or json

John Cai via GitGitGadget· May 27, 2022, 20:52 UTC · lore
From: John Cai <johncai86@gmail.com>

In order to allow users to use one executable for multiple hooks, provide a GIT_HOOK variable that is set to the hook event that triggered it.

Signed-off-by: John Cai <johncai86@gmail.com>
---
    hook: Provide GIT_HOOK for all hooks
    
    In order to allow users to use one executable for multiple hooks,
    provide a GIT_HOOK variable that is set to the hook event that triggered
    it.
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1271%2Fjohn-cai%2Fjc%2Fset-git-hooks-env-var-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1271/john-cai/jc/set-git-hooks-env-var-v1
Pull-Request: https://github.com/git/git/pull/1271
 Documentation/githooks.txt |  4 ++++
 hook.c                     |  2 ++
 t/t1800-hook.sh            | 12 ++++++++++++
 3 files changed, 18 insertions(+)
Show changes to 3 files +18 −0

Documentation/githooks.txt, hook.c, t/t1800-hook.sh

diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
index a16e62bc8c8..b27ed8d11b6 100644
--- a/Documentation/githooks.txt
+++ b/Documentation/githooks.txt
@@ -31,6 +31,10 @@ Hooks can get their arguments via the environment, command-line
 arguments, and stdin. See the documentation for each hook below for
 details.
 
+The `$GIT_HOOK` environment variable is passed to all hooks and holds the
+triggering hook event, eg: `pre-commit`, `update`, etc. This allows one
+executable to be used for multiple hooks.
+
 `git init` may copy hooks to the new repository, depending on its
 configuration. See the "TEMPLATE DIRECTORY" section in
 linkgit:git-init[1] for details. When the rest of this document refers
diff --git a/hook.c b/hook.c
index 1d51be3b77a..966f2114db4 100644
--- a/hook.c
+++ b/hook.c
@@ -144,6 +144,8 @@ int run_hooks_opt(const char *hook_name, struct run_hooks_opt *options)
 		cb_data.hook_path = abs_path.buf;
 	}
 
+	strvec_pushf(&cb_data.options->env,"GIT_HOOK=%s", hook_name);
+
 	run_processes_parallel_tr2(jobs,
 				   pick_next_hook,
 				   notify_start_failure,
diff --git a/t/t1800-hook.sh b/t/t1800-hook.sh
index 26ed5e11bc8..a22c1a82a5e 100755
--- a/t/t1800-hook.sh
+++ b/t/t1800-hook.sh
@@ -38,6 +38,18 @@ test_expect_success 'git hook run: basic' '
 	test_cmp expect actual
 '
 
+test_expect_success 'git hook run: $GIT_HOOK' '
+	test_hook test-hook <<-EOF &&
+	printenv GIT_HOOK
+	EOF
+
+	cat >expect <<-\EOF &&
+	test-hook
+	EOF
+	git hook run test-hook 2>actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'git hook run: stdout and stderr both write to our stderr' '
 	test_hook test-hook <<-EOF &&
 	echo >&1 Will end up on stderr

base-commit: 8ddf593a250e07d388059f7e3f471078e1d2ed5c

-- 
gitgitgadget
Junio C Hamano· May 27, 2022, 21:20 UTC · re: John Cai via GitGitGadget · lore

Re: [PATCH] hook: provide GIT_HOOK for all hooks

"John Cai via GitGitGadget" <gitgitgadget@gmail.com> writes:
Show 5 quoted lines
> From: John Cai <johncai86@gmail.com>
>
> In order to allow users to use one executable for multiple hooks,
> provide a GIT_HOOK variable that is set to the hook event that triggered
> it.

I agree it would be handy to give hooks to play multiple roles by dispatching on its name, just like our "git" potty can dispatch built-ins when called "git-foo".

I do not think GIT_HOOK is a good name for the environment variable that is used for that purpose, though. It is easily mistaken as if end users can set GIT_HOOK environment themselves to point at a program and cause "git" to run it whenever it may want to run any hook, for example. IOW, the name is overly broad.

How about calling it with a name with "HOOK" and "NAME" in it?
Show 12 quoted lines
> diff --git a/t/t1800-hook.sh b/t/t1800-hook.sh
> index 26ed5e11bc8..a22c1a82a5e 100755
> --- a/t/t1800-hook.sh
> +++ b/t/t1800-hook.sh
> @@ -38,6 +38,18 @@ test_expect_success 'git hook run: basic' '
>  	test_cmp expect actual
>  '
>  
> +test_expect_success 'git hook run: $GIT_HOOK' '
> +	test_hook test-hook <<-EOF &&
> +	printenv GIT_HOOK
> +	EOF
This will introduce the first hit from "git grep printenv".
It is not even in POSIX.  Do we absolutely need to?
Perhaps
    echo "$GIT_HOOK"

is sufficient, or if you want to distinguish an unset and set to empty string:

    if test "${GIT_HOOK+set}" = "set"
    then
        echo "GIT_HOOK is set to '$GIT_HOOK'"
    else
        echo "GIT_HOOK is unset"
	exit 1
    fi
may be another way.
> +	cat >expect <<-\EOF &&
> +	test-hook
> +	EOF
For one-liner, 
	echo test-hook >expect &&
should be a more compact and equally understandable way to write this.
> +	git hook run test-hook 2>actual &&
> +	test_cmp expect actual
> +'
John Cai· May 28, 2022, 04:26 UTC · re: Junio C Hamano · lore

Re: [PATCH] hook: provide GIT_HOOK for all hooks

Hi Junio
On 27 May 2022, at 17:20, Junio C Hamano wrote:
Show 17 quoted lines
> "John Cai via GitGitGadget" <gitgitgadget@gmail.com> writes:
>
>> From: John Cai <johncai86@gmail.com>
>>
>> In order to allow users to use one executable for multiple hooks,
>> provide a GIT_HOOK variable that is set to the hook event that triggered
>> it.
>
> I agree it would be handy to give hooks to play multiple roles by
> dispatching on its name, just like our "git" potty can dispatch
> built-ins when called "git-foo".
>
> I do not think GIT_HOOK is a good name for the environment variable
> that is used for that purpose, though.  It is easily mistaken as if
> end users can set GIT_HOOK environment themselves to point at a
> program and cause "git" to run it whenever it may want to run any
> hook, for example.  IOW, the name is overly broad.
Yes, I see what you mean. It would be good to pick a more specific variable.
>
> How about calling it with a name with "HOOK" and "NAME" in it?
For lack of imagination, would GIT_HOOK_NAME still be too broad?
Show 17 quoted lines
>
>> diff --git a/t/t1800-hook.sh b/t/t1800-hook.sh
>> index 26ed5e11bc8..a22c1a82a5e 100755
>> --- a/t/t1800-hook.sh
>> +++ b/t/t1800-hook.sh
>> @@ -38,6 +38,18 @@ test_expect_success 'git hook run: basic' '
>>  	test_cmp expect actual
>>  '
>>
>> +test_expect_success 'git hook run: $GIT_HOOK' '
>> +	test_hook test-hook <<-EOF &&
>> +	printenv GIT_HOOK
>> +	EOF
>
> This will introduce the first hit from "git grep printenv".
>
> It is not even in POSIX.  Do we absolutely need to?
certainly not, I'll change this.
Show 27 quoted lines
>
> Perhaps
>
>     echo "$GIT_HOOK"
>
> is sufficient, or if you want to distinguish an unset and set to
> empty string:
>
>     if test "${GIT_HOOK+set}" = "set"
>     then
>         echo "GIT_HOOK is set to '$GIT_HOOK'"
>     else
>         echo "GIT_HOOK is unset"
> 	exit 1
>     fi
>
> may be another way.
>
>> +	cat >expect <<-\EOF &&
>> +	test-hook
>> +	EOF
>
> For one-liner,
>
> 	echo test-hook >expect &&
>
> should be a more compact and equally understandable way to write this.
good point!
>
>> +	git hook run test-hook 2>actual &&
>> +	test_cmp expect actual
>> +'
Ævar Arnfjörð Bjarmason· May 28, 2022, 15:53 UTC · re: John Cai via GitGitGadget · lore

Re: [PATCH] hook: provide GIT_HOOK for all hooks

On Fri, May 27 2022, John Cai via GitGitGadget wrote:
Show 5 quoted lines
> From: John Cai <johncai86@gmail.com>
>
> In order to allow users to use one executable for multiple hooks,
> provide a GIT_HOOK variable that is set to the hook event that triggered
> it.

You can use one executable for multiple hooks already, I've written such dispatchers that just look at the argv of the process.

What we will need something like this for is for the config-based hooks, and I think it makes sense to have a facility that's portable across both methods of hook invocations.

I really don't mind this change, and I think it's a good one to make.

But the commit message & documentation here really should be updated to reflect that this is currently superfluous to inspecting argv in the hook process, and that we're providing this anyway for XYZ reason.

John Cai· May 28, 2022, 16:42 UTC · re: Ævar Arnfjörð Bjarmason · lore

Re: [PATCH] hook: provide GIT_HOOK for all hooks

Hi Ævar
On 28 May 2022, at 11:53, Ævar Arnfjörð Bjarmason wrote:
Show 14 quoted lines
> On Fri, May 27 2022, John Cai via GitGitGadget wrote:
>
>> From: John Cai <johncai86@gmail.com>
>>
>> In order to allow users to use one executable for multiple hooks,
>> provide a GIT_HOOK variable that is set to the hook event that triggered
>> it.
>
> You can use one executable for multiple hooks already, I've written such
> dispatchers that just look at the argv of the process.
>
> What we will need something like this for is for the config-based hooks,
> and I think it makes sense to have a facility that's portable across
> both methods of hook invocations.

Ah yes, thanks for pointing this out. I will re-roll the commit message as we as clarity the documentation.

Show 7 quoted lines
>
> I really don't mind this change, and I think it's a good one to
> make.
>
> But the commit message & documentation here really should be updated to
> reflect that this is currently superfluous to inspecting argv in the
> hook process, and that we're providing this anyway for XYZ reason.
Junio C Hamano· May 28, 2022, 17:24 UTC · re: Ævar Arnfjörð Bjarmason · lore

Re: [PATCH] hook: provide GIT_HOOK for all hooks

Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
> But the commit message & documentation here really should be updated to
> reflect that this is currently superfluous to inspecting argv in the
> hook process, and that we're providing this anyway for XYZ reason.

Or this probably is better added as part of the series that actually adds the mechanism to trigger hooks defined in the configuration file.

Then "we do not need it now, but we will in the future because we will do XYZ" does not have to be said, which is a huge plus.

Thanks.
John Cai· May 31, 2022, 01:31 UTC · re: Junio C Hamano · lore

Re: [PATCH] hook: provide GIT_HOOK for all hooks

On 28 May 2022, at 13:24, Junio C Hamano wrote:
Show 9 quoted lines
> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
>
>> But the commit message & documentation here really should be updated to
>> reflect that this is currently superfluous to inspecting argv in the
>> hook process, and that we're providing this anyway for XYZ reason.
>
> Or this probably is better added as part of the series that actually
> adds the mechanism to trigger hooks defined in the configuration
> file.

I don't mind including this as part of Ævar's config hook series. On the other hand this patch could allow the config hooks series to be smaller and more easily reviewed.

I'm okay either way--maybe Ævar can speak to what his preference is.
Show 5 quoted lines
>
> Then "we do not need it now, but we will in the future because we
> will do XYZ" does not have to be said, which is a huge plus.
>
> Thanks.

thanks John

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