Git repo prepare for backups and restore

backup_prep.sh

#!/bin/bash
#    05/26/2012 jag
#  COMPONENT_NAME: backup_prep.sh
#
#  ORIGIN: Jeffrey Gipson
#
#  Personal Proprietary
#  (C) COPYRIGHT 2012 Jeffrey Gipson
#  Unpublished work - All Rights Reserved
#
#  DESCRIPTION:
#
#     This script prepares the system for backup.
#
#  EXAMPLE:
#
#

function warn () { echo "$@" 1>&2; }
function die  () 
{  
  local code=1
  local message="Unknown error in ${FUNCNAME[1]}"
  
  if [[ "$1" =~ ^[0-9]+$ ]]; then
    code=$1
    shift
  fi
  message="$0"
  if [[ -n "$message" ]]; then
    warn "$message"
  fi
  exit $code
}

function find_git_repos ()
{
  find "${@:-/home}" -type d                     \
             -path */.gvfs -prune ! -name .gvfs  \
             -o -name .git                       \
             -exec /usr/bin/dirname {} \;
}

function reset_git_repo ()
{
  if [[ $# -ne 1 ]]; then
    die "${FUNCNAME}() usage error, no argument, expected path to repo"
  fi

  if [[ ! -d "$1/.git" ]]; then
    warn "$1 does not appear to be a non-bare git repo; skipping..."
    return
  fi

  pushd "$1" &>/dev/null

  if [[ ! -f "README.backup" ]]; then
    warn "$1 wasn't prepared for backup... skipping"
    return
  else
    rm -f README.backup
  fi

  if git reset --hard; then
    if [[ "$(git stash list -1 --format=%s)" == "On working: backup" ]]; then
      if ! git stash pop; then
        die "SERIOUS: unable to pop stash for $1"
      fi
    fi
    warn "$1 reset complete"
  else
    die "SERIOUS: unable to reset --hard for $1"
  fi
}

function prepare_git_repo ()
{
  if [[ $# -ne 1 ]]; then
    die "${FUNCNAME}() usage error, no argument, expected path to repo"
  fi

  if [[ ! -d "$1/.git" ]]; then
    warn "$1 does not appear to be a non-bare git repo; skipping..."
    return
  fi

  pushd "$1" &>/dev/null
  if git stash save backup && git ls-files -z | xargs -0 rm; then
    cat>>README.backup<<EOT
This folder has been prepped for backup. It should only be in this state
during the backup. If something has gone wrong, attempt to run:

  backup_prep.sh reset

If you need to reset it manually, then run:

  git reset --hard
  
  git stash list

If the top of the stash stack is "On working: backup" then pop the stash:

  git stash pop

Finally delete this file:

  command rm README.backup
EOT
    warn "$1 preparation completed"
  else
    warn "An error occurred, attempting to reset..."
    if reset_git_repo "$1"; then
      die 2 "reset successful for $1"
    else
      die "SERIOUS: unable to recover state for $1"
    fi
  fi
  popd &>/dev/null
}

function belt
{  
    echo "belt and suspenders: making extra backup in /tmp/gitrepobaks/tar"
    find_git_repos | tar cf /tmp/gitrepobaks.tar -T - 
}

case "$1" in
  prep)
    belt || die "belt broke!"
    while read repo; do
      prepare_git_repo "$repo"
    done < <(find_git_repos) 
    ;;

  reset)
    while read repo; do
      reset_git_repo "$repo"
    done < <(find_git_repos) 
    ;;

  belt)
    belt
    ;;

  list)
    find_git_repos
    ;;

  test)
    belt
    rm -rf /tmp/before /tmp/after
    mkdir /tmp/before /tmp/after
    pushd /tmp/before
    tar xf /tmp/gitrepobaks.tar
    cd ../after
    tar xf /tmp/gitrepobaks.tar
    while read repo; do
      prepare_git_repo "$repo"
    done < <(find_git_repos /tmp/after)
    while read repo; do
      reset_git_repo "$repo"
    done < <(find_git_repos /tmp/after)
    popd
    exec diff -ur /tmp/before /tmp/after | less
    ;;

  *)
    die 1 "Usage: $BASH_SOURCE (prep|reset)"
    ;;

esac