bind9/util/branchsync.sh

#!/bin/sh

# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
#
# SPDX-License-Identifier: MPL-2.0
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0.  If a copy of the MPL was not distributed with this
# file, you can obtain one at https://mozilla.org/MPL/2.0/.
#
# See the COPYRIGHT file distributed with this work for additional
# information regarding copyright ownership.

# branchsync:
# pull in changes from a main BIND 9 release branch to a subscription
# branch (e.g., from v9_9 to v9_9_sub).  This excludes commits from the
# 'tinderbox' user (copyright updates and doc regeneration) because those
# will be taken care of in the subscription branch itself.
#
# Most of the time, changes in the main branch will cherry-pick cleanly
# into the subscription branch. When one fails, we reset to the last
# commit that went cleanly, and send mail -- or, if running in interactive
# mode, we stop and allow the user to resolve conflicts.
#
# NOTE: This does not push changes to the repository; currently that's up
# to the caller.
#
# Usage:
# branchsync.sh [ -i ] [ -c ]
#   -i: interactive mode (don't reset and send mail)
#   -c: continue (conflicts are resolved; edit message and commit)

restore_files() {
  # restore the copyrights and api files
  git checkout HEAD -- util/copyrights lib/*/api
  # restore the generated documentation
  git checkout HEAD -- doc/arm/*.html doc/arm/Bv9ARM.pdf
  git checkout HEAD -- bin/*/*.html bin/*/*.[0-9]
  # don't update the EXCLUDED file
  if [ -f EXCLUDED ]; then
    git checkout HEAD -- EXCLUDED
  fi
}

savehash() {
  cat <<EOF >$1.new
SOURCEBRANCH=$2
LASTHASH=$3
EOF
  mv -f $1.new $1
  git add branchsync.dat
}

thisbranch() {
  git branch | grep '^\*' | cut -b3-
}

docommit() {
  # skip the commit if we're only updating branchsync.dat
  status=$(git status -suno | grep branchsync.dat)
  if [ -z "$status" ]; then
    return
  fi

  # pull in the log message from the cherry-picked commit
  git log -1 --pretty=format:%s%n%b $2 >orig_commit_msg.tmp
  author=$(git log -1 --pretty=format:"%aN <%aE>" $2)
  firstline=$(head -1 orig_commit_msg.tmp | sed 's/^\[[a-z0-9_]*\] //')
  tail -n +2 orig_commit_msg.tmp >remainder.tmp
  firstline="[$BRANCH] $firstline"
  echo $firstline >commit_msg.tmp
  cat remainder.tmp >>commit_msg.tmp
  echo "pulled from $1 by script." >>commit_msg.tmp
  echo "hash: $2" >>commit_msg.tmp
  msg=$(cat commit_msg.tmp)
  rm -f orig_commit_msg.tmp commit_msg.tmp remainder.tmp

  # commit
  git commit --no-verify --no-edit --author="$author" -m "$msg" || exit 1
}

BRANCH=$(thisbranch)

if [ ! -f branchsync.dat ]; then
  echo "$0: branchsync data file not found"
  exit 0
fi

. branchsync.dat

# check arguments
interactive=
continuing=
case $1 in
  '-i')
    interactive=yes
    ;;
  '-c')
    docommit $SOURCEBRANCH $LASTHASH
    interactive=yes
    continuing=yes
    ;;
  *)
    if [ $# -ne 0 ]; then
      echo "Usage: $0 [ -i ] [ -c ]" 1>&2
      exit 1
    fi
    ;;
esac

if [ -z "$continuing" ]; then
  status=$(git status -suno)
  if [ -n "$status" ]; then
    echo "Work tree is not clean. Clean up, or run with -c:"
    echo "$status"
    exit 1
  fi

  # make sure both branches are synced to the source repository
  git pull origin $BRANCH >/dev/null 2>&1
  git checkout -f $SOURCEBRANCH >/dev/null 2>&1
  git pull origin $SOURCEBRANCH >/dev/null 2>&1
  git checkout -f $BRANCH >/dev/null 2>&1
fi

# loop through commits looking for ones that should be cherry-picked
git log $SOURCEBRANCH --first-parent --reverse --format='%H %aN' $LASTHASH..$SOURCEBRANCH \
  | awk '$0 !~ /Tinderbox/ {print $1}' | {
  while read hash; do
    mainline=
    if [ $(git cat-file -p ${hash} | grep '^parent [0-9a-f][0-9a-f]*$' | wc -l) -gt 1 ]; then
      mainline="-m 1 "
    fi
    if git cherry-pick ${mainline} -xn ${hash}; then
      # cherry-pick was clean
      # restore the files that we don't want updated automatically
      restore_files

      # note which hash we're merging
      savehash branchsync.dat $SOURCEBRANCH $hash

      # fix the commit message, and commit
      docommit $SOURCEBRANCH $hash

      # move on to the next commit
      continue
    elif [ -n "$interactive" ]; then
      # interactive mode -- wait for user to fix things
      # first restore the files that we don't want updated automatically
      restore_files

      # note which hash we're merging
      savehash branchsync.dat $SOURCEBRANCH $hash
    else
      # noninteractive mode
      # reset everything
      git reset --hard

      # build mail message
      subject="Branch sync to $BRANCH failed"
      cat <<EOF >/tmp/branchmsg.$$
Attempt to cherry pick ${hash}
to $BRANCH failed.

Commit message of change was:
$(git log -1 --pretty=format:%s%n%b ${hash})
EOF

      # send mail
      cat /tmp/branchmsg.$$ | mail -s "$subject" bind-changes@isc.org
      rm /tmp/branchmsg.$$
    fi

    break
  done
}