pre-push

#!/usr/bin/env bash
#
# Usage: Copy this file to your repository's .git/hooks directory. Name the
# copy "pre-push" and set the executable bit.
#
#   cp gerrit-pre-push /path/to/repo/.git/hooks/pre-push \
#       && chmod +x /path/to/repo/.git/hooks/pre-push
#
# This hook checks for unwanted pushes to specific remotes by checking commit
# messages for bad patterns. If such a pattern is found, the push is aborted.
# This hook can also run additional checks when pushing to those remotes.
#
# # Selecting remotes #
#
# Run `git config jdkprepush.remotes "<remote_names>"`. Remote names should be
# a space-separated list. Additionally, the special name "GERRIT" can be used
# to check pushes to any remote when the remote ref starts with "refs/for/".
#
# If not specified in git config, the default value "GERRIT" is used. If
# specified but empty, this hook will not check any remotes.
#
# # Specifying patterns #
#
# Run `git config jdkprepush.patterns "<patterns>"`. Use a whitespace-separated
# list of regular expression patterns. If your patterns may include whitespace,
# you can use another separator character; in that case, also run
# `git config jdkprepush.separator '<char>'` to specify it.
#
# Patters are passed to git rev-list --grep. By default, patterns are case-
# insensitive.
#
# If not specified in git config, the default value "^(WIP|stash)" is used. If
# specified but empty, this hook will not look for any patterns.
#
# # Running additional checks #
#
# To run project-specific checks before pushing (e.g. a test suite), do either
# of the following:
#
# - Add a file named "pre-push-run-checks" in the .git/hooks directory. It will
#   be executed if pushing to Gerrit, and its exit status will be used as the
#   exit status for this hook.
#
# - Modify the block at the end of this file with your commands. (In that case,
#   make sure this isn't a symlinked file.)
#
# Remaining comments are copied from .git/hooks/pre-push.sample.
#
# -----
# An example hook script to verify what is about to be pushed. Called by "git
# push" after it has checked the remote status, but before anything has been
# pushed. If this script exits with a non-zero status nothing will be pushed.
#
# This hook is called with the following parameters:
#
# $1 -- Name of the remote to which the push is being done
# $2 -- URL to which the push is being done
#
# If pushing without using a named remote those arguments will be equal.
#
# Information about the commits which are being pushed is supplied as lines to
# the standard input in the form:
#
#   <local ref> <local sha1> <remote ref> <remote sha1>

remote="$1"
url="$2"

z40=0000000000000000000000000000000000000000

# read git config for remotes
# -> not specified -> "GERRIT"
# -> empty -> skip hook

# read git config for patterns (pattern?)
# -> not specified -> "^(WIP|stash)"
# -> empty -> don't look for patterns (but still run checks)

# while read
# - pass deletes through
# - check if we're interested (if not, pass)
#   - remote_ref in REMOTES, or GERRIT in REMOTES and remote_ref starts with refs/for/
# - mark run-checks
# - check patterns (unless patterns empty)

while read local_ref local_sha remote_ref remote_sha
do
  # Handle delete
  if [[ "$local_sha" = "$z40" ]]
  then
    echo "$local_ref, $remote_ref"
    :
  # Move along if we don't match refs/for/
  elif [[ ! "$remote_ref" =~ ^refs/for/.+ ]]
  then
    echo "$local_ref, $remote_ref"
    :
  else
    echo "$local_ref, $local_sha, $remote_ref, $remote_sha"
    if [[ "$remote_sha" = "$z40" ]]
    then
      # New branch, examine all commits
      branchname="${remote_ref#refs/for/}"

      if [[ "$branchname" =~ % ]]
      then
        # Gerrit allows various push-options by appending them to the remote
        # using "%<option>=<string>[,<option>=<string>...]". Strip this off.
        # TODO: '%' is a valid character in branch names, so this could mangle
        # the branch name. We should find a way to workaround that.
        echo "NOTE: stripping Gerrit push-options beginning at '%'"
        branchname=${branchname%%\%*}
      fi

      if git check-ref-format --allow-onelevel "$branchname"
      then
        range="${remote}/${branchname}..$local_sha"
      fi

      if [[ -z "$range" ]]
      then
        range="$local_sha"
      fi
    else
      # Update to existing branch, examine new commits
      range="$remote_sha..$local_sha"
    fi

    echo "Examining $range"

    # Check for WIP/stash commit
    commit=`git rev-list -n 1 -i --grep '^WIP' --grep '^stash' "$range"`
    if [[ -n "$commit" ]]
    then
      echo >&2 "Found WIP/stash commit in $local_ref, not pushing ($commit)"
      exit 1
    fi

    # In case you want to run any verifications
    run_checks=true
  fi
done

if [[ -n "$run_checks" ]]; then
  hookfile="$(git rev-parse --git-dir)/hooks/gerrit-pre-push"
  if [[ -e "$hookfile" ]]; then
    [[ -x "$hookfile" ]] && "$hookfile"
    exit $?
  fi
fi

exit 0