#!/bin/bash
#
# Tool to dump info from a singularity image
# Run this as "root" from _inside_ the container image,
# because it will interrogate the system using the image's
# contained files.
#
# This is for Debian-based image
#
# Usage:
#    simg-dump-info.sh  INFO_DIR  CONT_NAME  [IMAGE_ROOT_DIR]
#
# INFO_DIR is the location to dump the info files
# CONT_NAME is the name of the container (to be used as the basenames)
#
# Info dumped so far:
# - ${CONT_NAME}.files - actual list of files
# - ${CONT_NAME}.files-dpkg - registration of files according to dpkg
# - ${CONT_NAME}.lists-dpkg.tar - registration of files according to dpkg
#   (individual list files)
# - ${CONT_NAME}.dpkg-l - list of installed packages


_simg_list_all_files () {
    local ROOT_DIR="${1:-.}"

    find "$ROOT_DIR" -mount \
        | sort  \
        | awk -v ROOT="$ROOT_DIR" '
              BEGIN {
                  ROOTX = ROOT
                  gsub(/\/+$/, "", ROOTX)
                  ROOTX = (ROOTX "/")
                  len_ROOTX = length(ROOTX)
              }
              $0 == ROOT { next }
              (substr($0, 1, len_ROOTX) == ROOTX) {
                  print(substr($0, len_ROOTX))
                  next
              }
          '
}


set -e

MYSELF=$0
MYDIR=$(dirname "$MYSELF")

INFO_DIR=${1:?INFO_DIR required as arg 1}
CONT_NAME=${2:?CONT_NAME required as arg 2}
CONT_IMAGE_ROOT_DIR=${3:-/}


# Get the view of the files *ACTUALLY* residing in the container
_simg_list_all_files "${CONT_IMAGE_ROOT_DIR}" > "${INFO_DIR}/${CONT_NAME}.files"

dpkg -l > "${INFO_DIR}/${CONT_NAME}.dpkg-l"

# Get the view of files registered to dpkg
# (In some containers the files do not exist there because they
# were somehow deleted, e.g. doc files, man pages, ...)
(
    cd /var/lib/dpkg/info
    tar cf "${INFO_DIR}/${CONT_NAME}.lists-dpkg.tar" *.list
    cat *.list | sort | uniq > "${INFO_DIR}/${CONT_NAME}.dpkg-files"
)