.git/hooks/post-applypatch for rehashing with an original committer.

post-applypatch.sh

#!/bin/sh
. git-sh-setup

## XXX: For rehashing with an original comitter:
#
# Backgrounds:
# - {commit} includes ['tree', 'parent', 'author', 'committer']
# - When `git am` finished, generated an unexpected commit id.
#   - Check `git cat-file commit HEAD` and compare it.
# - `git am` handled only ['tree', 'parent', 'author']
#   - `git format-patch` includes only these metadatas.
#   - So the lack of 'committer' metadata caused wrong generated commit id.
# - Below codes run inside of `git am`
#   - Whenever patch file pipes in.
#
# HACK:
PATCH_APPLYING_AUTHOR="$(git rev-parse --git-path rebase-apply/author-sciprt)"
if [ -r $PATCH_APPLYING_AUTHOR ]
then
	# Setup the environment variables for an original committer metadata.
	source $PATCH_APPLYING_AUTHOR
	export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL GIT_AUTHOR_DATE
	export GIT_COMMITTER_NAME=$GIT_AUTHOR_NAME
	export GIT_COMMITTER_EMAIL=$GIT_AUTHOR_EMAIL
	export GIT_COMMITTER_DATE=$GIT_AUHTOR_DATE
	
	# Commit (rehash) with an original committer metadata.
	BEFORE="$(git rev-parse --verify --short HEAD)"
	git commit --amend -reset-author --no-edit --no-verify --quite
	AFTER="$(git rev-parse --verify --short HEAD)"
	
	# Report to user
	COMMIT_MSG_FILE="$(git rev-parse --git-path rebase-apply/final-commit)"
	COMMIT_MSG="$(head -n 1 $COMMIT_MSG_FILE)"
	echo "Rehashed: $COMMIT_MSG :: $AFTER"
	
	# TODO: (WIP) Recheck!
	EXPECTED_HASH_FILE="$(git rev-parse --git-path rebase-apply/abort-safety)"
	if [ -r $EXPECTED_HASH_FILE ]
	then
		EXPECTED_HASH="$(cat $EXPECTED_HASH_FILE)"
		if [ "$AFTER" != "$EXPECTED_HASH" ]
		then
			echo ""
			echo " Warning! Mismatched when patch generated.  (experimental)"
			echo "   - Before  : $BEFORE"
			echo "   - After   : $AFTER"
			echo "   - Expected: $EXPECTED_HASH"
			echo ""
		fi
	fi
fi
# END-OF-HACK