--- /dev/null
+#!/bin/sh
+
+# Copyright 2018 Paul Hänsch
+#
+# This is a file format helper, part of CGIlite.
+#
+# CGIlite is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# CGIlite is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with CGIlite. If not, see <http://www.gnu.org/licenses/>.
+
+[ -n "$include_storage" ] && return 0
+include_storage="$0"
+
+LOCK(){
+ local lock timeout block
+ lock="${1}.lock"
+ timeout="${2-20}"
+ if [ \! -w "${lock%/*}" ] || [ -e "$lock" -a \! -d "$lock" ]; then
+ printf 'Impossible to get lock: %s\n' "$lock" >&2
+ return 1
+ fi
+
+ while ! mkdir "$lock" 2>&-; do
+ block="$(cat "$lock/pid" || printf 1)"
+ if ! { ps -eo pid |grep -qwF "$block"; }; then
+ printf 'Overriding stale lock: %s\n' "$lock" >&2
+ break
+ fi
+ if [ $timeout -le 0 ]; then
+ printf 'Timeout while trying to get lock: %s\n' "$lock" >&2
+ return 1
+ fi
+ timeout=$((timeout - 1))
+ sleep 1
+ done
+ printf '%i\n' $$ >"${lock}/pid"
+ return 0
+}
+
+RELEASE(){
+ local lock
+ lock="${1}.lock"
+ if [ "$(cat "$lock/pid")" = "$$" ]; then
+ rm "$lock/pid"
+ if ! rmdir "$lock"; then
+ printf 'Cannot remove tainted lock: %s\n' "$lock" >&2
+ printf '%i\n' $$ >"${lock}/pid"
+ return 1
+ fi
+ return 0
+ else
+ printf 'Refusing to release foreign lock: %s\n' "$lock" >&2
+ return 1
+ fi
+}
+
+STRING='
+ s;\\;\\\\;g;
+ s;\n;\\n;g;
+ s;\t;\\t;g;
+ s;\r;\\r;g;
+ s;\+;\\+;g;
+ s; ;+;g;
+'
+
+STRING(){
+ { [ $# -eq 0 ] && cat || printf %s "$*"; } \
+ | sed -r ':X; $!{N;bX;}'"$STRING"
+}
+
+UNSTRING='
+ :UNSTRING_X
+ s;((^|[^\\])(\\\\)*)\\n;\1\n;g;
+ s;((^|[^\\])(\\\\)*)\\t;\1\t;g;
+ s;((^|[^\\])(\\\\)*)\\r;\1\r;g;
+ s;((^|[^\\])(\\\\)*)\+;\1 ;g;
+ tUNSTRING_X;
+ s;((^|[^\\])(\\\\)*)\\\+;\1+;g;
+ s;\\\\;\\;g;
+'
+UNSTRING(){
+ { [ $# -eq 0 ] && cat || printf %s "$*"; } \
+ | sed -r "$UNSTRING"
+}