unixorn/git-extra-commands

#!/usr/bin/env bash
#
# git-rebase-theirs - Resolve rebase conflicts by favoring 'theirs' version
#
#    Copyright (C) 2012 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
#
#    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 3 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 see <http://www.gnu.org/licenses/gpl.html>

#Defaults:
verbose=0
backup=1
inplace=0
ext=".bak"

message() { printf "%s\n" "$1" >&2 ; }
# shellcheck disable=SC2104
skip()    { message "skipping ${2:-$file}${1:+: $1}"; continue ; }
argerr()  { printf "%s: %s\n" "$myname" "${1:-error}" >&2 ; usage 1 ; }
invalid() { argerr "invalid option: $1" ; }
missing() { argerr "missing${1:+ $1} operand." ; }

usage() {
    cat <<- USAGE
    Usage: $myname [options] [--] FILE...
    USAGE
    if [[ "$1" ]] ; then
        cat >&2 <<- USAGE
        Try '$myname --help' for more information.
        USAGE
        exit 1
    fi
    cat <<-USAGE

    Resolve git rebase conflicts in FILE(s) by favoring 'theirs' version

    When using git rebase, conflicts are usually wanted to be resolved
    by favoring the <working branch> version (the branch being rebased,
    'theirs' side in a rebase), instead of the <upstream> version (the
    base branch, 'ours' side)

    But git rebase --strategy -X theirs is only available from git 1.7.3
    For older versions, $myname is the solution. And Despite the name,
    it's also useful for fixing failed cherry-picks

    It works by discarding all lines between '<<<<<<< ' and '========'
    inclusive, and also the the '>>>>>> commit' marker.

    By default it outputs to stdout, but files can be edited in-place
    using --in-place, which, unlike sed, creates a backup by default.

    Options:
      -h|--help            show this page.
      -v|--verbose         print more details in stderr.

      --in-place[=SUFFIX]  edit files in place, creating a backup with
                           SUFFIX extension. Default if blank is "$ext"

      --no-backup          disables backup

    Copyright (C) 2012 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
    License: GPLv3 or later. See <http://www.gnu.org/licenses/gpl.html>
    USAGE
    exit 0
}
myname="${0##*/}"

# Option handling
files=()
while (( $# )); do
    case "$1" in
    -h|--help     ) usage            ;;
    -v|--verbose  ) verbose=1        ;;
    --no-backup   ) backup=0         ;;
    --in-place    ) inplace=1        ;;
    --in-place=*  ) inplace=1
                    suffix="${1#*=}" ;;
    --            ) shift ; break    ;;
    -*            ) invalid "$1"     ;;
    *             ) files+=( "$1" )  ;;
    esac
    shift
done
files+=( "$@" )

if ! (( "${#files[@]}" )); then missing "FILE"; fi

ext=${suffix:-$ext}

for file in "${files[@]}"; do

    if ! [[ -f "$file" ]]; then skip "not a valid file"; fi

    if ((inplace)); then
        outfile=$(mktemp) || skip "could not create temporary file"
        # shellcheck disable=SC2064
        trap "rm -f -- '$outfile'" EXIT
        cp "$file" "$outfile" || skip
        exec 3>"$outfile"
    else
        exec 3>&1
    fi

    # Do the magic :)
    awk '/^<<<<<<<+ .+$/,/^=+$/{next} /^>>>>>>>+ /{next} 1' "$file" >&3

    exec 3>&-

    if ! ((inplace)); then continue; fi

    diff "$file" "$outfile" >/dev/null && skip "no conflict markers found"

    if ((backup)); then cp "$file" "$file$ext" || skip "could not backup"; fi

    cp "$outfile" "$file" || skip "could not edit in-place"
    rm -f -- "$outfile"
    trap - EXIT

    if ((verbose)); then message "resolved ${file}"; fi
done