a git extention to import patches from the RPM spec file to a git branch

git-spec-import

#!/bin/sh
#
# git spec-import
#   a git extention to import patches from the RPM spec file to a git branch
#
# Copyright(c) 2019 Keisuke MORI ([email protected])
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
# sample .gitconfig:
#
#[spec-import "resource-agents.spec"]
#	basecommitmacro = upstream_version
#	excluderegex = ^Patch100[0-9]$
#	dist = .el8
#[spec-import "pacemaker.spec"]
#	basecommitmacro = commit
#	excluderegex = 
#	dist = .el8
#[spec-import "fence-agents.spec"]
#	basecommittagformat = v%{VERSION}
#	excluderegex = ^Patch100[0-9]$
#	dist = .el8
#	# workaround for rpmspec failure
#	rpmspecsed = /^Requires: %/d
#[spec-import "corosync.spec"]
#	basecommittagformat = v%{VERSION}
#	excluderegex = 
#	dist = .el8
#[spec-import "pcs.spec"]
#	basecommittagformat = %{VERSION}
#	excluderegex = 
#	dist = .el8
#	# workaround for rpmspec failure
#	rpmspecsed = /^Suggests: \\|^Requires: (/d
#


function git_apply_patch()
{
  local pfile
  pfile="$1"
  pfilepath="${PATCHDIR}/${pfile}"

  if grep '^From ' "${pfilepath}" >/dev/null 2>&1 ; then
    # mbox format generated by git format-patch
    git am "$pfilepath" || git_am_try_resolve || error_exit "ERROR: failed to apply $pfilepath"

  else
    # regular diff format
    git apply --index "$pfilepath" || error_exit "ERROR: failed to apply $pfilepath"
    git commit -m "$pfile" || error_exit "ERROR: failed to commit $pfile"

  fi
}

function git_am_try_resolve()
{
  rc=1
  while [ $rc -ne 0 ]; do
    patch -p1 < $(git rev-parse --git-dir)/rebase-apply/patch || return 1
    git add -u .
    git am --resolved
    rc=$?
  done
}

function merge_backport_branches()
{
  git checkout $BASE_COMMIT || error_exit "ERROR: base commit not found: $BASE_COMMIT"

  # TODO: when already exists
  git checkout -b $BRANCH_BASE
  git checkout -b $BRANCH_NAME

  grep '^Patch[0-9]*:' $SPECFILE | while read pline; do
    set -- $pline
    pnum="$(echo $1 | tr -d ':')"
    pfile="$2"

    pbranch="${pnum}-${pfile}"

    # skip excluded patches
    expr match "$pnum" "$EXCLUDE_REGEX" >/dev/null && continue

    
    git branch | grep "$pbranch" >/dev/null 2>&1;
    rc=$?
    if [ $rc -ne 0 ]; then
      git checkout -b $pbranch

      git_apply_patch $pfile

      git checkout $BRANCH_NAME
    fi

    git merge $pbranch

  done || error_exit "ERROR: merge failed"
}

function git_branch_delete()
{
  git branch -D "$1" 2>&1 | grep -v "^error: branch .* not found."
}
  
function delete_backport_branches()
{
  # try to checkout to the base of the branch, or to master if not determined
  [ -z "$BASE_COMMIT" ] && BASE_COMMIT="$(git rev-parse $BRANCH_BASE)" || BASE_COMMIT=""
  [ -z "$BASE_COMMIT" ] && BASE_COMMIT="master"
  git checkout $BASE_COMMIT || error_exit "ERROR: base commit not found: $BASE_COMMIT"

  git_branch_delete $BRANCH_BASE
  git_branch_delete $BRANCH_NAME

  grep '^Patch[0-9]*:' $SPECFILE | while read pline; do
    set -- $pline
    pnum="$(echo $1 | tr -d ':')"
    pfile="$2"

    pbranch="${pnum}-${pfile}"

    git_branch_delete $pbranch

  done
}

function error_exit()
{
  echo "$@"
  exit 1
}

function on_exit()
{
  # clean up temporarly files if exists
  [ -f "$TMPSPECFILE" ] && rm -f "$TMPSPECFILE"
}


function read_config()
{
  local section base_commit_macro exclude_regex dist
  local branch_name
  section="spec-import.$(basename $SPECFILE)"
  dist=$(git config --get "${section}.dist")
  rpmspecopts=$(git config --get "${section}.rpmspecopts")
  rpmspec_sed=$(git config --get "${section}.rpmspecsed")
  base_commit_macro=$(git config --get "${section}.basecommitmacro")
  base_commit_tagformat=$(git config --get "${section}.basecommittagformat")
  exclude_regex=$(git config --get "${section}.excluderegex")

  # use modified TMPSPECFILE if the spec file can not be parsed 
  # by rpmspec command
  if [ -n "$rpmspec_sed" ]; then
    TMPSPECFILE="${SPECFILE}.git-import"
    sed -e "$rpmspec_sed" "$SPECFILE" > "$TMPSPECFILE"
    SPECFILE="$TMPSPECFILE"
  fi

  # build rpmspec command line; 
  #  - needs to be eval'ed to pass the quoted arguments properly
  rpmspec="rpmspec -D '%_sourcedir $PATCHDIR'"
  [ -n "$dist" ] && rpmspec="$rpmspec -D '%dist $dist'"
  [ -n "$rpmspecopts" ] && rpmspec="$rpmspec $rpmspecopts"

  branch_name="$(eval $rpmspec -q --queryformat='%{VERSION}-%{RELEASE}' --srpm ${SPECFILE})"
  [ -n "$branch_name" ] && BRANCH_NAME="$branch_name"


  [ -n "$base_commit_macro" ] && BASE_COMMIT=$(grep "^%global $base_commit_macro " ${SPECFILE} | awk '{print $3}')
  [ -n "$base_commit_tagformat" ] && BASE_COMMIT="$(eval $rpmspec -q --queryformat='$base_commit_tagformat' --srpm ${SPECFILE})"


  [ -n "$exclude_regex" ] && EXCLUDE_REGEX="$exclude_regex"
}

function dump_config()
{
  echo "SPECFILE = $SPECFILE"
  echo "BRANCH_NAME = $BRANCH_NAME"
  echo "BRANCH_BASE = $BRANCH_BASE"
  echo "BASE_COMMIT = $BASE_COMMIT"
  echo "EXCLUDE_REGEX = $EXCLUDE_REGEX"
}

function usage()
{
  echo "usage: $0 [-b branch_name] [-m] [-C] [-D] SPECFILE"
  exit 0
}

### Main 

## parse args
opt_branch=""
opt_check=0
opt_delete=0
opt_currentbase=0
while getopts "b:mCD" opt; do
  case $opt in
    b) opt_branch="$OPTARG";;
    m) opt_currentbase=1;;
    C) opt_check=1;;
    D) opt_delete=1;;
    *) usage;;
  esac
done
shift $(($OPTIND - 1))

[ $# -ne 0 ] || usage

SPECFILE="$1"
PATCHDIR="$(dirname $SPECFILE)"

TMPSPECFILE=""
trap -- on_exit EXIT

## config variabes to customize for the spec file
BRANCH_NAME='spec-import'
BASE_COMMIT=""
EXCLUDE_REGEX=""

read_config

# override BRANCH_NAME if specified 
[ -n "$opt_branch" ] && BRANCH_NAME="$opt_branch"
BRANCH_BASE="${BRANCH_NAME}-base"
# force to branch from the current commit if specified
[ $opt_currentbase -ne 0 ] && BASE_COMMIT=""

if [ $opt_check -ne 0 ]; then
  dump_config
  exit 0
fi
if [ $opt_delete -ne 0 ]; then
  delete_backport_branches
  exit 0
fi
if [ $opt_currentbase -eq 0 ] && [ -z "$BASE_COMMIT" ]; then
  echo "ERROR: base commit can not be determined"
  echo "       use -m option to force to branch from the current commit,"
  echo "       or add 'basecommitmacro' or 'basecommittagformat' parameter to .gitconfig"
  usage
fi

merge_backport_branches


echo
echo "Succeeded."