scripts: add fwdport/fwdabort.sh for forward porting commits between branches (#2597)

Signed-off-by: Mike Ralphson <[email protected]>

Author: MikeRalphson

scripts/fwdabort.sh

@@ -0,0 +1,10 @@
+#!/bin/sh
+
+# Aborts a fwdport.sh run cleanly
+
+# Author: @MikeRalphson
+
+git am -i --abort
+rm -f *.mbox *.patch *.rej
+git checkout main
+

scripts/fwdport.sh

@@ -0,0 +1,100 @@
+#!/bin/sh
+
+# Forward ports changes from the spec file of a source branch to the spec file of a target branch
+# For example: porting interim changes made in v3.1.x patch releases to the v3.2.0 branch
+
+# This script is designed to be run once per branch, when interim changes need merging in
+# before another branch is released. It is not intended to be run multiple times to keep
+# two branches in sync.
+
+# Author: @MikeRalphson
+# Issues: https://github.com/OAI/OpenAPI-Specification/pull/2163
+
+mainbranch=main
+myremote=origin
+upstream=upstream
+
+source=$1
+target=$2
+
+if [ -z "$source" ]; then
+  echo You must specify a source and target branch
+  exit 1
+fi
+if [ -z "$target" ]; then
+  echo You must specify a source and target branch
+  exit 1
+fi
+
+echo Checking working dir...
+status=`git ls-files -m`
+if [ -z "$status" ]; then
+  echo All clear
+else
+  echo You have a dirty working tree, aborting
+  echo ${status}
+  exit 1
+fi
+
+cruft=`ls -1 *.patch *.rej *.mbox 2>/dev/null`
+if [ -z "$cruft" ]; then
+  echo No .patch, .rej or .mbox files found, continuing
+else
+  echo .patch / .rej / .mbox files found, aborting
+  exit 1
+fi
+
+tmpbranch=forward-port-${source}
+existing=`git branch | grep ${tmpbranch}`
+if [ -z "$existing" ]; then
+  echo No matching temp branch found, continuing
+else
+  echo Temp branch ${tmpbranch} already exists, aborting
+  exit 1
+fi
+
+srcver=`echo $source | sed s/-dev//g | sed s/v//g`.md
+tgtver=`echo $target | sed s/-dev//g | sed s/v//g`.md
+
+echo Forward-porting changes from ${source}:versions/${srcver} to ${target}:${tgtver}
+echo You may use the commands \'git fwdskip\' and \'git fwdcont\' to skip patches, or to continue after manually fixing.
+echo Use `fwdabort.sh` to abort cleanly.
+echo
+echo Due to a bug in \`git am\`, git v2.22.1+ is required, you\'re running:
+git --version
+echo
+echo Press a key to continue...
+read
+
+git config --add rerere.enabled true
+git config alias.fwdskip '!git am -i --skip'
+git config alias.fwdcont '!git am -i --continue'
+
+git checkout ${source}
+git pull ${upstream} ${source}
+
+# look at using git merge-base as an alternative? say if we branched 3.1.0 part way through 3.0.2's life
+
+firstsrc=`git log --abbrev-commit --format=format:%H -n 1 --reverse -- versions/${srcver}`
+lastsrc=`git log --abbrev-commit --format=format:%H -- versions/${srcver} | tail -n 1`
+changes=`git log --format=format:%H --reverse versions/${srcver}`
+
+echo Applying changes from ${firstsrc} to ${lastsrc}
+
+# remove first (creation) commit and uniq without sorting
+oIFS="$IFS"
+IFS=' '
+changes=`echo ${changes} | tail -n +2 | awk '!x[$0]++'`
+IFS="$oIFS"
+
+for c in ${changes}; do
+  git format-patch --stdout -1 $c | sed s/${srcver}/${tgtver}/g > $c.patch
+done
+
+git checkout ${target}
+git pull ${upstream} ${target}
+git checkout -b ${tmpbranch}
+cat *.patch > fwdport.mbox
+rm -f *.patch
+git am -3 --interactive --ignore-whitespace -s fwdport.mbox
+