Feature 57 (config and provisioning): modules declare config and provisions, their files rendered from templates; synced with main (issues of feature 57, 874)

modules/clipmenu/files/bin/clipmenud-session

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+#!/bin/sh
+# clipmenud as the operator's user unit starts it, written by the mesh (module clipmenu). Replaced at every push.
+#
+# The account's service manager starts before the X server does, and has a DISPLAY only once the session's
+# xinitrc has handed it over (module xorg). So this waits, quietly, until the display is known, and exits
+# only when the session ends with it: a quick exit would run the unit into its start limit. DISPLAY, when
+# the manager has it, wins. Without it, exactly one X socket names the display; none or several (a
+# second server beside the session) wait for the session's own to arrive.
+# A running process does not see what the session hands the manager later, so each pass asks the manager.
+until [ -n "$DISPLAY" ]; do
+	for pair in $(systemctl --user show-environment 2>/dev/null | grep -E '^(DISPLAY|XAUTHORITY)='); do
+		export "$pair"
+	done
+	[ -n "$DISPLAY" ] && break
+	set -- /tmp/.X11-unix/X*
+	if [ $# -eq 1 ] && [ -S "$1" ]; then
+		DISPLAY=":${1##*/X}"
+		export DISPLAY
+	else
+		sleep 1
+	fi
+done
+if [ -z "$XAUTHORITY" ] && [ -r "$HOME/.Xauthority" ]; then
+	XAUTHORITY="$HOME/.Xauthority"
+	export XAUTHORITY
+fi
+# clipmenud allows one daemon per account: it takes an exclusive flock on its session_lock file and exits
+# with status 2 when that is held. After a delivery without a new login, the session's older clipmenud (from
+# its xinitrc) still holds it, and a start would run the unit round its restart loop. So this waits, quietly,
+# until the lock is free: it looks at the same file clipmenud locks (the directory is clipmenud's own rule)
+# and lets go at once. Exit status 1 is "held" for util-linux and BusyBox flock alike (no -E: BusyBox lacks it); any other outcome starts clipmenud, which says its own
+# error. Another daemon winning the gap between look and start costs one restart, not a loop.
+lock="${CM_DIR:-${XDG_RUNTIME_DIR-${TMPDIR-/tmp}}}/clipmenu.6.$USER/session_lock"
+while [ -e "$lock" ]; do
+	flock -n "$lock" true
+	[ $? -eq 1 ] || break
+	sleep 2
+done
+PATH="/usr/local/lib/mesh-clipmenu:$PATH"
+export PATH
+exec clipmenud

modules/clipmenu/files/bin/xsel

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+#!/bin/sh
+# xsel as clipmenud sees it, written by the mesh (module clipmenu). Replaced at every push.
+#
+# clipmenud records text, and reads a selection with `timeout 1 xsel -o`. A selection holding an
+# image (a screenshot copied as image/png) is sent in pieces; one second is too short for megabytes,
+# timeout kills xsel half way, and the program owning the image waits for ever for a reader that is
+# gone. From then on nothing can ask the clipboard anything: pastes hang, and an Electron app that
+# asks on its main thread freezes. So a read goes ahead only when the selection offers text.
+case " $* " in
+*" -o "* | *" --output "*)
+	selection=clipboard
+	case " $* " in
+	*" --primary "* | *" -p "*) selection=primary ;;
+	*" --secondary "* | *" -s "*) selection=secondary ;;
+	esac
+	targets=$(timeout 1 xclip -selection "$selection" -t TARGETS -o 2>/dev/null) || exit 1
+	printf '%s\n' "$targets" | grep -qxE 'UTF8_STRING|STRING|TEXT|text/plain(;charset=utf-8)?' || exit 1
+	;;
+esac
+exec /usr/bin/xsel "$@"