add i3 locker script

diff --git a/locker b/locker
new file mode 100755 (executable)
index 0000000..14b026f
--- /dev/null
+++ b/locker
@@ -0,0 +1,51 @@
+#!/bin/bash
+
+# Example locker script -- demonstrates how to use the --transfer-sleep-lock
+# option with i3lock's forking mode to delay sleep until the screen is locked.
+
+## CONFIGURATION ##############################################################
+
+# Options to pass to i3lock
+i3lock_options="-c 000000"
+
+# Run before starting the locker
+pre_lock() {
+    #mpc pause
+    return
+}
+
+# Run after the locker exits
+post_lock() {
+    return
+}
+
+###############################################################################
+
+pre_lock
+
+# We set a trap to kill the locker if we get killed, then start the locker and
+# wait for it to exit. The waiting is not that straightforward when the locker
+# forks, so we use this polling only if we have a sleep lock to deal with.
+if [[ -e /dev/fd/${XSS_SLEEP_LOCK_FD:--1} ]]; then
+    kill_i3lock() {
+        pkill -xu $EUID "$@" i3lock
+    }
+
+    trap kill_i3lock TERM INT
+
+    # we have to make sure the locker does not inherit a copy of the lock fd
+    i3lock $i3lock_options {XSS_SLEEP_LOCK_FD}<&-
+
+    # now close our fd (only remaining copy) to indicate we're ready to sleep
+    exec {XSS_SLEEP_LOCK_FD}<&-
+
+    while kill_i3lock -0; do
+        sleep 0.5
+    done
+else
+    trap 'kill %%' TERM INT
+    i3lock -n $i3lock_options &
+    wait
+fi
+
+post_lock