Git hook that determines the author based on the email address in a SSH key. Doesn't work because Git doesn't check the config between pre-commit and commit.

post-commit

#!/bin/sh

# Retrieve author information as Git sees it while commiting
AUTHORINFO=$(git var GIT_AUTHOR_IDENT) || exit 1
NAME=$(printf '%s\n' "${AUTHORINFO}" | sed -n 's/^\(.*\) <.*$/\1/p')
EMAIL=$(printf '%s\n' "${AUTHORINFO}" | sed -n 's/^.* <\(.*\)> .*$/\1/p')

printf "AUTHORINFO: %s\n" "${AUTHORINFO}"
printf "NAME: %s\n" "${NAME}"
printf "EMAIL: %s\n" "${EMAIL}"

# Retrieve author information of the Repo user
REPONAME=$(git config --get repouser.name)
REPOEMAIL=$(git config --get repouser.email)

printf "REPONAME: %s\n" "${REPONAME}"
printf "REPOEMAIL: %s\n" "${REPOEMAIL}"

# If the current configured user is not the Repo user
if [ "${NAME}" != "${REPONAME}" ] || [ "${EMAIL}" != "${REPOEMAIL}" ]; then
	# Reset the Repo user
	git config user.name "${REPONAME}"
	git config user.email "${REPOEMAIL}"

	echo "Config reset!"
fi

pre-commit

#!/bin/sh

# Retrieve author information as Git sees it while commiting
AUTHORINFO=$(git var GIT_AUTHOR_IDENT) || exit 1
NAME=$(printf '%s\n\n' "${AUTHORINFO}" | sed -n 's/^\(.*\) <.*$/\1/p')
EMAIL=$(printf '%s\n\n' "${AUTHORINFO}" | sed -n 's/^.* <\(.*\)> .*$/\1/p')

printf "AUTHORINFO: %s\n" "${AUTHORINFO}"
printf "NAME: %s\n" "${NAME}"
printf "EMAIL: %s\n" "${EMAIL}"

# Retrieve author information of the Repo user
REPONAME=$(git config --get repouser.name)
REPOEMAIL=$(git config --get repouser.email)

printf "REPONAME: %s\n" "${REPONAME}"
printf "REPOEMAIL: %s\n" "${REPOEMAIL}"

# If we're trying to commit as the Repo user
#if [ "${NAME}" = "${REPONAME}" ] || [ "${EMAIL}" = "${REPOEMAIL}" ]; then
	while [ 1 ]; do
		# Check if we can access the SSH key and derive a previous committer from that
		SSHUSER=$(ssh-add -l 2>/dev/null| cut -d" " -f3 | cut -d"@" -f1 | cut -d"+" -f1)
		GITCOMMIT=$(git rev-list --all -i --author=${SSHUSER} | head -n1)
		printf "SSHUSER: %s\n" "${SSHUSER}"
		printf "GITCOMMIT: %s\n" "${GITCOMMIT}"
		if [ -z "$SSHUSER" ] || [ -z "$GITCOMMIT" ]; then
			echo "Could not determine Git user from SSH key"
			break;
		fi

		GITUSER=$(git show -s --pretty=format:%aN ${GITCOMMIT})
		GITEMAIL=$(git show -s --pretty=format:%aE ${GITCOMMIT})
		printf "GITUSER: %s\n" "${GITUSER}"
		printf "GITEMAIL: %s\n" "${GITEMAIL}"
		if [ -z "$GITUSER" ] || [ -z "$GITEMAIL" ]; then
			echo "Could not read previous Git commit for SSH user ${SSHUSER}"
			break;
		fi

		# Set the found values
		# Note that the post-commit hook will reset these config options
		# to the Repo user after committing
		git config user.name "${GITUSER}"
		git config user.email "${GITEMAIL}"
		echo "Config set!"
		exit 0
	done

	echo "Fail!"

	# If all fails, show error message with solution
    cat <<EOF >&2
Please commit under your own name and email instead of "${NAME} <${EMAIL}>":

GIT_AUTHOR_NAME="Your Name" GIT_AUTHOR_EMAIL="[email protected]" git commit
EOF
	exit 2
#fi