[Ovirt-devel] coming soon: prohibition on pushing bad-whitespace-adding changes

[Jim Meyering]

In the next couple of days, I expect to enable a git hook on the server
that will deny any attempt to push a change that adds "bad" whitespace.
In the mean time, you who will be pushing or posting changes should be
sure to enable commit-time checks for white space:

  Run "chmod a+x .git/hooks/update" (if you already have the file,
  .git/hooks/update) or "cd .git/hooks && cp -a update.sample update"
  if you have one named update.sample.

That will help you by making your local commits fail whenever
a change adds bad (e.g. trailing) whitespace.  If that happens,
it tells you which file/line-number are affected, and you just
edit those lines and retry the commit.

If you forget and commit (locally) changes that add trailing blanks,
you'll have to edit those change sets e.g., via "git rebase -i next",
before you can push them.

FYI, I've included below the patch I'll apply to the server-side
.git/hooks/update script.

For reference, to disable it, you would do this on the server:

    git --git-dir=/var/www/git/ovirt.git/hooks \
      config hooks.allowbadwhitespace false

>From 1660659d0d38e1138ca402e486b62292e018d8fd Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering at redhat.com>
Date: Tue, 29 Jul 2008 18:16:50 +0200
Subject: [PATCH] Reject any attempt to push a change that adds "bad" whitespace.

Override with this:
	git config hooks.allowbadwhitespace true

---
 templates/hooks--update.sample |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/templates/hooks--update.sample b/templates/hooks--update.sample
index 93c6055..fa372c3 100755
--- a/templates/hooks--update.sample
+++ b/templates/hooks--update.sample
@@ -56,6 +56,7 @@ else
 	newrev_type=$(git-cat-file -t $newrev)
 fi

+check_diff=no
 case "$refname","$newrev_type" in
 	refs/tags/*,commit)
 		# un-annotated tag
@@ -78,6 +79,7 @@ case "$refname","$newrev_type" in
 		;;
 	refs/heads/*,commit)
 		# branch
+		check_diff=yes
 		;;
 	refs/heads/*,delete)
 		# delete branch
@@ -88,6 +90,7 @@ case "$refname","$newrev_type" in
 		;;
 	refs/remotes/*,commit)
 		# tracking branch
+		check_diff=yes
 		;;
 	refs/remotes/*,delete)
 		# delete tracking branch
@@ -103,5 +106,12 @@ case "$refname","$newrev_type" in
 		;;
 esac

+if [ $check_diff = yes ]; then
+	allow_bad_whitespace=$(git config --bool hooks.allowbadwhitespace)
+	if [ "$allow_bad_whitespace" != "true" ]; then
+		exec git diff --check $oldrev $newrev --
+	fi
+fi
+
 # --- Finished
 exit 0
--
1.5.6.4.435.g780ea