From 79fafa3c6aa574f641d634fd3e136f29ec0ee9cf Mon Sep 17 00:00:00 2001
From: Cem Keylan <cem@ckyln.com>
Date: Wed, 16 Sep 2020 15:55:20 +0300
Subject: respawn: add seperate shell utility instead of running while loops

Technically, these are the same shell commands, but since they are run
by a separate shell, they are easier to predict and easier to kill.
---
 Makefile           |  2 ++
 contrib/getty.boot |  4 ++--
 contrib/respawn    | 23 +++++++++++++++++++++++
 contrib/runit.boot |  2 +-
 4 files changed, 28 insertions(+), 3 deletions(-)
 create mode 100644 contrib/respawn

diff --git a/Makefile b/Makefile
index fe893ad..be66946 100644
--- a/Makefile
+++ b/Makefile
@@ -23,6 +23,8 @@ install: bin/shalt
 	mkdir -p ${DESTDIR}${CONFDIR} ${DESTDIR}${INITDIR} ${DESTDIR}${BINDIR}
 	cp bin/shalt ${DESTDIR}${BINDIR}/shalt
 	chmod 755 ${DESTDIR}${BINDIR}/shalt
+	cp contrib/respawn ${DESTDIR}${BINDIR}/respawn
+	chmod 755 ${DESTDIR}${BINDIR}/respawn
 	cp rc.lib rc.boot rc.shutdown ${DESTDIR}${INITDIR}
 	chmod 755 ${DESTDIR}${INITDIR}/rc.boot ${DESTDIR}${INITDIR}/rc.shutdown
 	cp rc.conf contrib/runit.boot contrib/getty.boot ${DESTDIR}${CONFDIR}
diff --git a/contrib/getty.boot b/contrib/getty.boot
index bb5a5e3..eaf90d9 100644
--- a/contrib/getty.boot
+++ b/contrib/getty.boot
@@ -1,4 +1,4 @@
 for getty in 1 2 3 4 5 6; do
-    while :; do /sbin/getty 38400 tty${getty} 2>&1 ; done &  # busybox getty
-    while :; do /sbin/getty /dev/tty${getty} linux 2>&1 ; done &  # ubase getty
+    respawn getty 38400 tty${getty} 2>&1 ; done &  # busybox getty
+    respawn getty /dev/tty${getty} linux 2>&1 ; done &  # ubase getty
 done
diff --git a/contrib/respawn b/contrib/respawn
new file mode 100644
index 0000000..1b914ea
--- /dev/null
+++ b/contrib/respawn
@@ -0,0 +1,23 @@
+#!/bin/sh -e
+# POSIX shell variant for ubase respawn
+
+usage() {
+    printf 'usage: %s [-d N] cmd [args...]\n' "${0##*/}"
+    exit "${1:-0}"
+}
+
+die() { printf '%s\n' "$@" >&2; exit 1;}
+
+case "$1" in
+    -d) [ "$3" ] || usage 1
+        [ "$2" -gt 0 ] || die "Not a number: $2"
+        delay=$2; shift 2
+        ;;
+    --help|-h|'') usage ;;
+    -*) usage 1
+esac
+
+while :; do
+    "$@"
+    [ "$delay" ] && sleep "$delay"
+done
diff --git a/contrib/runit.boot b/contrib/runit.boot
index aafe142..f8858c9 100644
--- a/contrib/runit.boot
+++ b/contrib/runit.boot
@@ -1 +1 @@
-while :; do /usr/bin/runsvdir -P /var/service ; done &
+respawn runsvdir -P /var/service ; done &
-- 
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