# Looking for pre-commit hook to check whitespace errors but not for all files

3 messages from 2013-12-14 to 2013-12-16. Participants: Paul Menzel, John Keeping, Junio C Hamano.
Thread: https://gitlist.dev/t/35531

## Paul Menzel, 2013-12-14 15:28

Subject: Looking for pre-commit hook to check whitespace errors but not for all files
Message-ID: <1387034894.4636.9.camel@mattotaupa>
URL: https://gitlist.dev/e/1387034894.4636.9.camel%40mattotaupa

```
Dear git folks,


in coreboot we try to check for whitespace errors before committing. Of
course a pre-commit hook is the way to go, but unfortunately it is not
so simple (at least for me) as the following requirements exist.

1. Only the files actually committed should be checked. That means
running `git commit -a`, abort that and then running `git commit
some/file` should only check `some/file` for whitespace errors.

2. There are certain files that are allowed to have whitespace errors.
In our case these are `*.patch` and `*.diff` files which by design seem
to contain whitespace error.

Currently the whole tree is checked, which takes a lot of time [1].

I tried to come up with a patch [2], but failed so far. Best would be to
have

    $ git diff --check --only-committed-files --exclude "*patch$"

where I could not find a way for the last to switches.

Currently, I would use

    $ git diff-index --cached --name-only $against -- | grep -v patch$

and pass that list to some whitespace check program. Unfortunately that
still does not fulfill the first requirement.

What am I missing to solve this elegantly?


Thanks,

Paul


[1] http://review.coreboot.org/gitweb?p=coreboot.git;a=blob;f=util/lint/lint-stable-003-whitespace;h=1e824a1e76e37ce641b91c75f2f78e0e2abfd37f;hb=HEAD
[2] http://review.coreboot.org/#/c/3340/

```

## John Keeping, 2013-12-14 16:59

Subject: Re: Looking for pre-commit hook to check whitespace errors but not for all files
Message-ID: <20131214165914.GJ3163@serenity.lan>
URL: https://gitlist.dev/e/20131214165914.GJ3163%40serenity.lan
In-Reply-To: <1387034894.4636.9.camel@mattotaupa>

```
On Sat, Dec 14, 2013 at 04:28:14PM +0100, Paul Menzel wrote:
> in coreboot we try to check for whitespace errors before committing. Of
> course a pre-commit hook is the way to go, but unfortunately it is not
> so simple (at least for me) as the following requirements exist.
> 
> 1. Only the files actually committed should be checked. That means
> running `git commit -a`, abort that and then running `git commit
> some/file` should only check `some/file` for whitespace errors.
> 
> 2. There are certain files that are allowed to have whitespace errors.
> In our case these are `*.patch` and `*.diff` files which by design seem
> to contain whitespace error.
> 
> Currently the whole tree is checked, which takes a lot of time [1].
> 
> I tried to come up with a patch [2], but failed so far. Best would be to
> have
> 
>     $ git diff --check --only-committed-files --exclude "*patch$"
> 
> where I could not find a way for the last to switches.
> 
> Currently, I would use
> 
>     $ git diff-index --cached --name-only $against -- | grep -v patch$
> 
> and pass that list to some whitespace check program. Unfortunately that
> still does not fulfill the first requirement.
> 
> What am I missing to solve this elegantly?

I think you want to combine .gitattributes with something like the
diff-index above:

	$ cat >.gitattributes <<-EOF
	*.patch whitespace=false
	*.diff whitespace=false
	EOF

	$ git diff-index --check --cached $against --

```

## Junio C Hamano, 2013-12-16 19:06

Subject: Re: Looking for pre-commit hook to check whitespace errors but not for all files
Message-ID: <xmqq8uvkpqcs.fsf@gitster.dls.corp.google.com>
URL: https://gitlist.dev/e/xmqq8uvkpqcs.fsf%40gitster.dls.corp.google.com
In-Reply-To: <1387034894.4636.9.camel@mattotaupa>

```
Paul Menzel <paulepanter@users.sourceforge.net> writes:

> 1. Only the files actually committed should be checked. That means
> running `git commit -a`, abort that and then running `git commit
> some/file` should only check `some/file` for whitespace errors.

Doesn't hooks/pre-commit.sample we ship already gets this right?

	$ git init foobar && cd foobar
	$ mv .git/hooks/pre-commit.sample .git/hooks/pre-commit
        $ for i in foo bar; do echo $i >$i.txt; done
        $ git commit -m initial
        $ for i in foo bar; do echo "$i " >$i.txt; done
        $ git commit -a
        bar.txt:1: trailing whitespace.
        +bar
        foo.txt:1: trailing whitespace.
        +foo
        $ git commit foo.txt
        foo.txt:1: trailing whitespace.
        +foo

> 2. There are certain files that are allowed to have whitespace errors.

As John Keeping alraedy pointed out, you can use the attributes
mechanism to mark what kind of payload each path has to control
this kind of thing.

```