From cdb4bd7abb307db1fd68b314a4785cbea8dcdf86 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Sun, 13 Jul 2014 23:36:41 -0400
Subject: install-lilo: Detect boot/root unless under chroot

---
diff --git a/install-lilo.sh b/install-lilo.sh
index e980baa..ff3dd2c 100644
--- a/install-lilo.sh
+++ b/install-lilo.sh
@@ -8,12 +8,20 @@ main()
 
 	[ "x$(id -u)" = 'x0' ] || error 'Must be run as the superuser'
 
-	if [ ${#} -ne 2 ]; then
+	if [ ${#} -eq 0 ]; then
+		if is_chroot; then
+			error 'Running under chroot; %s' \
+				'please specify the boot and root devices'
+		fi
+		boot="$(mountpoint -n /boot | cut -d ' ' -f 1)"
+		root="$(mountpoint -n / | cut -d ' ' -f 1)"
+	elif [ ${#} -eq 2 ]; then
+		boot="${1}"
+		root="${2}"
+	else
 		usage >&2
 		exit 1
 	fi
-	boot="${1}"
-	root="${2}"
 
 	[ -e "${boot}" ] || error 'Boot device not found'
 	[ -e /etc/lilo.conf.in ] || \
@@ -28,7 +36,7 @@ main()
 
 usage()
 {
-	printf 'Usage: install-lilo <boot> <root>\n'
+	printf 'Usage: install-lilo [<boot> <root>]\n'
 }
 
 error()
@@ -40,4 +48,9 @@ error()
 	exit 2
 }
 
+is_chroot()
+{
+	awk '$5 == "/" { exit(1); };' "/proc/${$}/mountinfo"
+}
+
 main "${@}"
--
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