SyncBranches

#!/bin/bash

### Synchronizes two branches by interactively asking for commits
### to cherry-pick since a given (non-inclusive) starting git reference.
###
### Usage: SyncBranches -h
### Usage:
### Usage: SyncBranches [-p] -s <src-branch> -d <dst-branch> <since-tag-or-commit>
### Usage:     -p: do not pick anything, just print what is missing
### Usage:     -s <src-branch> or -d <dst-branch>: note that branch names can
### Usage:         be remote names. To use local branches, you must have
### Usage:         checked them out first. Remote dest branches can only be
### Usage:         used for printing the differences.
### Usage:
### Usage: Examples: SyncBranches -s remotes/origin/comp -d comp_gcc481 HG1406f
### Usage:           SyncBranches -p -s remotes/origin/comp -d remotes/origin/comp_gcc481 remotes/origin/comp~20

usage()
{
  perl -ne '/^### Usage:/ && do { s/^### ?//; print }' < $0
  exit 1
}

help()
{
  perl -ne '/^###/ && do { s/^### ?//; print }' < $0
  exit 0
}

p=
for arg; do
  case $arg in
    -h) help ;;
    -p) p=true; shift;;
    -s) srcbranch=$2; shift; shift ;;
    -d) dstbranch=$2; shift; shift ;;
    -*) usage ;;
  esac
done
start=$1
[ $# = 1 ] || { usage; exit 1; }

# check the repo has been cloned
if ! git log -1 &> /dev/null; then
  echo "Could not find a repository in the current directory. Clone it first."
  exit 1
fi

# check start tag/commit exists on src branch
if ! git branch -a --contains $start 2>/dev/null | egrep -q " $srcbranch\$"; then
  echo "Could not find starting tag or commit $start on $srcbranch."
  exit 1
fi

# when not in print-only mode, check the dest branch is local and we are there
if [ -z "$p" ]; then
  if [ "${dstbranch:0:8}" = "remotes/" ]; then
    echo "Cannot use a remote branch as destine for checky-picking.";
    exit 1
  fi
  if [ $(git rev-parse --abbrev-ref HEAD) != $dstbranch ]; then
    echo "You must git-checkout the local $dstbranch branch first."
    exit 1
  fi
fi

for cmt in $(git rev-list --topo-order $start..$srcbranch --reverse); do
  msg=$(git show -s --oneline $cmt|cut -d" " -f2-)
  printf "%s %70s" "(${cmt:0:7})" "$msg"
  if git log -s --oneline -50 $dstbranch | grep -q "$msg"; then
    printf "%8s%18s\n" "" "[ALREADY PICKED]"
  else
    printf "%8s" "$($p echo -n '? (y/n)')"
    $p read -s answer
    case $answer in
      y) printf "%18s\n" "[    PICKING...]"; git cherry-pick $cmt || break;;
      *) printf "%18s\n" "[    NOT PICKED]";;
    esac;
  fi
done