#!/bin/sh -eu
# SYNTAX: $database_pattern -- $snapshot_eval
# DESCRIPTION: crée un instantané pour chaque base de données MySQL $database donnée
# DESCRIPTION: dans ~backup/snapshot/mysql/"$database",
# DESCRIPTION: puis évalue $snapshot_eval,
# DESCRIPTION: puis efface l'instantané.
${TRACE:+set -x}

test "$(id -u)" = "$(id -u backup)"

database_pattern=$1; shift
test ! "${1-}" = -- || shift
test ! $# = 0 || set -- :

install -d -m 770 -o backup -g backup \
 ~backup/snapshot/mysql

snapshot () {
	local database="$1"; shift
	test ! -e ~backup/snapshot/mysql/$database
		# NOTE: soit une sauvegarde est déjà en cours,
		#       soit une précédente a échoué.
	can_hotcopy=yes
	while IFS='	' read -r table engine
	 do
		case $engine in
		 (MyISAM|ARCHIVE) :;;
		 (*) can_hotcopy=no;;
		 esac
	 done <<-EOF
		$(mysql -u backup --batch --skip-column-names <<-EOF
				SELECT table_name,engine
					FROM information_schema.tables
					WHERE table_schema = '$database';
				EOF
		 )
		EOF
	case $can_hotcopy in
	 (yes)
		cd /
		sudo -u root find ~mysql-data -mindepth 1 -maxdepth 1 -type d -exec \
		 install -d -m 750 -o mysql -g backup {} +
		cd - >/dev/null 2>&1
		test "${TRACE:+set}" || quiet=--quiet
		mysqlhotcopy --method=cp -u backup ${quiet:-} \
		 "$database" ~backup/snapshot/mysql
		;;
	 (no)
		install -d -m 770 -o backup -g backup \
		 ~backup/snapshot/mysql/"$database"
		mysqldump --opt --events -u backup ${TRACE:+--verbose} \
		 --result-file ~backup/snapshot/mysql/$database/dump.sql \
		 "$database"
		;;
	 esac
	eval "$@"
	rm -rf \
	 ~backup/snapshot/mysql/"$database"
 }

exit=0
while IFS='	' read -r database
 do if ! snapshot "$database" "$@"
	 then
		exit=1
		cat >&2 <<-EOF
			ERROR: snapshot "$database" "$@"
			EOF
	 fi
 done <<-EOF
	$(mysql -u backup --batch --skip-column-names <<-EOF
		SELECT schema_name
			FROM information_schema.schemata
			WHERE schema_name NOT IN ('information_schema', 'performance_schema')
			AND   schema_name LIKE '$database_pattern';
		EOF
	 )
	EOF
exit $exit