From c0a40dd2df551e5e7cda8ba7b8f987bc52c81dce Mon Sep 17 00:00:00 2001
From: Maniack Crudelis <maniackcrudelis@users.noreply.github.com>
Date: Mon, 22 May 2017 15:24:16 +0200
Subject: [PATCH] New helpers ynh_store_file_checksum and
 ynh_backup_if_checksum_is_different (#286)

* New helpers ynh_store_checksum_config and ynh_compare_checksum_config

Helpers for avoid destruction of personalised config files.
If the config file was manually modified, make a backup of it.

The name of this backup is returned, so the packager can choose which of this both file will used by default.

* Implement @JimboJoe's comments.
* Setting local variables as local
* Adding warning about $app that should be defined
* Remove "globally" in comment to limit confusion
* Remove "globally" in comment to limit confusion
* Remove compress and use /home/yunohost.conf/backup
* Changing timestamp format to match regen-conf's
* Tested and fixed ;)
---
 data/helpers.d/filesystem | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/data/helpers.d/filesystem b/data/helpers.d/filesystem
index 0d13c4825..f0f3afb06 100644
--- a/data/helpers.d/filesystem
+++ b/data/helpers.d/filesystem
@@ -81,6 +81,44 @@ properly with chmod/chown." >&2
     echo $TMP_DIR
 }
 
+# Calculate and store a file checksum into the app settings
+#
+# $app should be defined when calling this helper
+#
+# usage: ynh_store_file_checksum file
+# | arg: file - The file on which the checksum will performed, then stored.
+ynh_store_file_checksum () {
+	local checksum_setting_name=checksum_${1//[\/ ]/_}	# Replace all '/' and ' ' by '_'
+	ynh_app_setting_set $app $checksum_setting_name $(sudo md5sum "$1" | cut -d' ' -f1)
+}
+
+# Verify the checksum and backup the file if it's different
+# This helper is primarily meant to allow to easily backup personalised/manually 
+# modified config files.
+#
+# $app should be defined when calling this helper
+#
+# usage: ynh_backup_if_checksum_is_different file
+# | arg: file - The file on which the checksum test will be perfomed.
+#
+# | ret: Return the name a the backup file, or nothing
+ynh_backup_if_checksum_is_different () {
+	local file=$1
+	local checksum_setting_name=checksum_${file//[\/ ]/_}	# Replace all '/' and ' ' by '_'
+	local checksum_value=$(ynh_app_setting_get $app $checksum_setting_name)
+	if [ -n "$checksum_value" ]
+	then	# Proceed only if a value was stored into the app settings
+		if ! echo "$checksum_value $file" | sudo md5sum -c --status
+		then	# If the checksum is now different
+			backup_file="/home/yunohost.conf/backup/$file.backup.$(date '+%Y%m%d.%H%M%S')"
+			sudo mkdir -p "$(dirname "$backup_file")"
+			sudo cp -a "$file" "$backup_file"	# Backup the current file
+			echo "File $file has been manually modified since the installation or last upgrade. So it has been duplicated in $backup_file" >&2
+			echo "$backup_file"	# Return the name of the backup file
+		fi
+	fi
+}
+
 # Remove a file or a directory securely
 #
 # usage: ynh_secure_remove path_to_remove