Utilities: Added LogoutHook scripts for emulated NVRAM saving.

Utilities/LogoutHook/LogoutHook.command

+#!/bin/sh
+
+#
+# Copyright © 2019 Rodion Shingarev. All rights reserved.
+# Slight optimizations by PMheart and vit9696.
+#
+
+abort() {
+  echo "Fatal error: ${1}"
+  exit 1
+}
+
+if [ ! -x /usr/bin/dirname ] || [ ! -x /usr/sbin/nvram ] || [ ! -x /usr/bin/grep ] || [ ! -x /bin/chmod ] || [ ! -x /usr/bin/sed ] || [ ! -x /usr/bin/base64 ] || [ ! -x /bin/rm ] || [ ! -x /bin/mkdir ] || [ ! -x /bin/cat ] || [ ! -x /bin/dd ] || [ ! -x /usr/bin/stat ] || [ ! -x /usr/libexec/PlistBuddy ] || [ ! -x /usr/sbin/ioreg ] || [ ! -x /usr/bin/xxd ] || [ ! -x /usr/sbin/diskutil ] || [ ! -x /bin/cp ] || [ ! -x /usr/bin/wc ]; then
+  abort "Unix environment is broken!"
+fi
+
+cd "$(/usr/bin/dirname "${0}")" || abort "Failed to enter working directory!"
+
+nvram=/usr/sbin/nvram
+if [ -z "$("${nvram}" -x '8BE4DF61-93CA-11D2-AA0D-00E098032B8C:BootOrder' | /usr/bin/grep 'xml')" ]; then
+  nvram=./nvram.mojave
+  if [ ! -f "${nvram}" ]; then
+    abort "${nvram} does NOT exist!"
+  elif [ ! -x "${nvram}" ]; then
+    abort "${nvram} is not executable!"
+  fi
+fi
+
+getKey() {
+  local key="$1"
+  "${nvram}" -x "${key}" | /usr/bin/sed '/\<data\>/,/\<\/data\>/!d;//d' | /usr/bin/base64 --decode
+}
+
+/bin/rm -rf dumps
+/bin/mkdir dumps || abort "Failed to create dumps directory!"
+cd dumps         || abort "Failed to enter dumps directory!"
+
+"${nvram}" -xp > ./nvram1.plist || abort "Failed to dump nvram!"
+
+getKey '8BE4DF61-93CA-11D2-AA0D-00E098032B8C:Boot0080' > ./Boot0080
+if [ ! -z "$(/bin/cat ./Boot0080)" ]; then
+  getKey 'efi-boot-device-data' > efi-boot-device-data || abort "Failed to retrieve efi-boot-device-data!"
+  /bin/dd seek=24 if=efi-boot-device-data of=Boot0080 bs=1 count=$(/usr/bin/stat -f%z efi-boot-device-data)    || abort "Failed to fill Boot0080 with efi-boot-device-data!"
+  /usr/libexec/PlistBuddy -c "Import Add:8BE4DF61-93CA-11D2-AA0D-00E098032B8C:Boot0080 Boot0080" ./nvram.plist || abort "Failed to import Boot0080!"
+fi
+
+for key in BootOrder BootCurrent BootNext Boot008{1..3}; do
+  getKey "8BE4DF61-93CA-11D2-AA0D-00E098032B8C:${key}" > "${key}"
+  if [ ! -z "$(/bin/cat "${key}")" ]; then
+    /usr/libexec/PlistBuddy -c "Import Add:8BE4DF61-93CA-11D2-AA0D-00E098032B8C:${key} ${key}" ./nvram.plist || abort "Failed to import ${key} from 8BE4DF61-93CA-11D2-AA0D-00E098032B8C!"
+  fi
+done
+
+/usr/libexec/PlistBuddy -c "Add Version integer 1"                                       ./nvram.plist || abort "Failed to add Version!"
+/usr/libexec/PlistBuddy -c "Add Add:7C436110-AB2A-4BBB-A880-FE41995C9F82 dict"           ./nvram.plist || abort "Failed to add dict 7C436110-AB2A-4BBB-A880-FE41995C9F82"
+/usr/libexec/PlistBuddy -c "Merge nvram1.plist Add:7C436110-AB2A-4BBB-A880-FE41995C9F82" ./nvram.plist || abort "Failed to merge with nvram1.plist!"
+
+UUID="$("${nvram}" 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102:boot-path | /usr/bin/sed 's/.*GPT,\([^,]*\),.*/\1/')"
+if [ "$(printf "${UUID}" | /usr/bin/wc -c)" -eq 36 ] && [ -z "$(echo "${UUID}" | /usr/bin/sed 's/[-0-9A-F]//g')" ]; then
+  /usr/sbin/diskutil mount "${UUID}" || abort "Failed to mount ${UUID}!"
+  /bin/cp ./nvram.plist "$(/usr/sbin/diskutil info "${UUID}" | /usr/bin/sed -n 's/.*Mount Point: *//p')" || abort "Failed to copy nvram.plist!"
+  exit 0
+else
+  abort "Illegal UUID or unknown loader!"
+fi
+
+/bin/rm -rf dumps

Utilities/LogoutHook/README.md

+LogoutHook
+===========
+
+## Installation
+```sudo defaults write com.apple.loginwindow LogoutHook /path/to/LogoutHook.command```
+
+## Notes
+`LogoutHook.command` highly depends on macOS `nvram` utility supporting `-x` option, which is unavailable on 10.12 and below. (Our `nvram.mojave` somehow fixes that issue by invoking it instead of system one)
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