#!/bin/bash

# Compute checksums for important data, and report changed or invalid 
# checksums.
# This should help to identify bit rot among rarely-used files.

mailto=root@localhost

if ! [ $( which cshatag ) ]; then
	echo "cshatag is not installed. Exiting."
	exit
fi

if ! [ $( which pcre2grep ) ]; then
	echo "pcre2grep is not installed. Exiting."
	exit
fi

shatag="cshatag"

for dir in /data/www /data/home ; do

	output=$( find "${dir}" -xdev -type f -exec ${shatag} {} \; )
	final_output=
	corrupt_output=$( echo "${output}" | grep -v "<ok>" | pcre2grep -vM '<outdated>.*\n.*stored:.*\n.*actual.*' )
	outdated_output=$( echo "${output}" | grep -v "<ok>" | pcre2grep -vM '<corrupt>.*\n.*stored:.*\n.*actual.*' )
	subject="Changed files in ${dir}"

	if [ -n "${corrupt_output}" ]; then
		final_output=$( cat <<-END_CORRUPT
			${final_output}

			The following files may be corrupted:

			${corrupt_output}

		END_CORRUPT
		)
		subject="CORRUPT files in ${dir}"
	fi
	if [ -n "${outdated_output}" ]; then
		modified_output=$( echo "${outdated_output}" | pcre2grep -vM '<outdated>.*\n.*stored:.*0000000000.000000000.*\n.*actual.*' )
		final_output=$( cat <<-END_OUTDATED
			${final_output}

			The following files have been modified:

			${modified_output}

		END_OUTDATED
		)
	fi

	if [ -n "${final_output}" ]; then
	       cat <<-END_FINAL | mail -s "${subject}" "${mailto}"
The following files have changed on disk.

If this is unexpected (that is, you haven't opened and re-saved these
files), they may have become corrupted. Please forward this list to your
systems administrator and request they be restored from backups.
${final_output}
		END_FINAL
	fi
done

# for shatag:
#	db=$( echo $dir | sed 's/[\/ ]/-/g' | sed 's/^-//' )
#	output=$( find "${dir}" -type f -exec ${shatag} -d "/root/${db}.shatagdb" -vqpt {} + 2>&1 )
#	outdated_output=$( echo "${output}" | grep -v "<missing>" )
#
#	corrupt_output=$( echo "${output}" | grep -v "<ok>" | awk -v SKIP=-1 '/<outdated>/ { SKIP = 2 } SKIP-- >= 0 {next } 1' )
#	outdated_output=$( echo "${output}" | grep -v "<ok>" | awk -v SKIP=-1 '/<corrupt>/ { SKIP = 2 } SKIP-- >= 0 {next } 1' )