dshasum

#!/usr/bin/env bash

# 
# dshasum
# approach to caculate a folder/directory SHA checksums
#
# 
# Usage info
show_help() {
cat << EOF
Directory SHA checksum (dshasum): Approach to caculate a folder/directory SHA checksums
Tony Liu, 2018-19 version 1.0.1
   
Usage: $(basename $0) -[h|?|v] [-f algorithm] [-p algorithm] [-t cheksum] path ...

      path           A full path of a directory
      -p algorithm   Path checksum algorithm, default=1
                     Valide shasum algorithm option, 1(default), 224, 256, 384, 512, 512224, 512256
      -f algorithm   files inside path checksum algorithm
                     default: equal to -p option
      -h|-?          Show this help
      -v             Verbose mode, which is good for debuging
      -t             [not implemented in this version]

Examples:
      $(basename $0) -p 256 /var/root /bin
      $(basename $0) -p 256 -f 1 /var/root
      $(basename $0) -vp 224 /var/root
EOF
}

printInfo()
{
   [[ $verbose -eq 1 ]] && echo "$1"
}

#
# allFileShasum()
# Get checksum of all files in a directory 
# Input: <Directory>, <Algorithm>
# Output: formatted file shasum strings in order 
# Return:
#    0 = Caculate folder OK
#    1 = Caculate one file OK
#  251 = Not a folder or file, or no access to it
#  252 = access Folder error
#  253 = access file error
#
allFileShasum()
{
   path="$1"
   opt="$2"

   [[ -z "${opt// }" ]] && opt="1"
   # -----------
   if [[ -f "$path" ]]; then
      if sum=$(/usr/bin/shasum -a $opt "$each"); then
         echo "$sum"
         return 1
      else
         return 253
      fi
   fi
   # -----------
   [[ -d "$path" ]] || return 251;

   curPath=$(pwd)
   cd "$path" || return 252
   filelist=" - [Directory-Hash]"
   IFS=$'\n'
   NL=$'\n'
   for each in $(/usr/bin/find -xd * -type f -not -name ".DS_Store" | sort); do
      if sum=$(/usr/bin/shasum -a $opt "$each"); then
         filelist="$filelist${NL}- $sum"
      else
         return 253
      fi
   done
   echo "$filelist"
   cd "$curPath"
}

#
# pathShasum()
# Caculate shasum base on the $1 string
# Input: <String> <Algorithm>
# Output: shasum string
# Return: 0
#
pathShasum()
{
   opt="$2"
   [[ -z "${opt// }" ]] && opt="1"
   echo -n "$1" | /usr/bin/shasum -a $opt | /usr/bin/awk '{print $1}'
   return 0
}

# Initialize our own variables:
verbose=0
path=""
pathAlg="1"
fileAlg=""

#-------------------------------------------------------------
# read the options
OPTIND=1         # Reset in case getopts has been used previously in the shell.
while getopts "h?vp:f:t:" opt; do
   case "$opt" in
   h|\?) show_help; exit 1 ;;
   v)  verbose=1 ;;
   p)  pathAlg="$OPTARG" ;;
   f)  fileAlg="$OPTARG" ;;
   t)  checkString="$OPTARG" ;; 
   esac
done
[ -z "$fileAlg" ] &&  fileAlg="$pathAlg"
#-------------------------------------------------------------
# process the rest Path ... arguments
shift $((OPTIND-1)); [ "${1:-}" = "--" ] && shift
printInfo "Verbose=$verbose, Path Algorithm=$pathAlg, File Algorithm=$fileAlg, CheckString=$checkString, Path=$*"

while [[ $# -gt 0 ]]; do
   eachPath="$1"
   printInfo "Start process path=$1"
   [ -d "$eachPath" ] || { echo "Error: access $eachPath"; exit 250; }
   check=$(allFileShasum "$eachPath" "$fileAlg")
   [[ "$?" != "0" ]] && { echo "Error: file shasum return $?."; exit 250; }
   printInfo "$check"
   check=$(pathShasum "$check" "$pathAlg")
   echo "$check, $eachPath"
   shift
done
exit 0