Added new multi bootloader helper functions

* Added: functions/bootloaders.sh . This file adds bootloader functions that are heavily used in efi scenarios where a bootloader can act as a first or an extra bootloader.

Since the introduction of the new switch:

--bootloaders

you can setup it like this:

--bootloaders=syslinux,grub-efi

.

This means that syslinux is the first bootloader and grub-efi is the extra bootloader.

* Added new bootloader functions: Check_Non_First_Bootloader and Check_Non_Extra_Bootloader.

These functions let each one of the bootloaders abort the build because
they cannot perform a role either as a first bootloader or as an extra bootloader.

* Added bootloader functions: Check_First_Bootloader_Role, Check_Extra_Bootloader_Role and Check_Any_Bootloader_Role

These functions let bootloaders to force their default role in a single line.

At the same time many binary bootloaders were rewritten to make use of the new bootloader role functions explained above.

These roles were enforced:

binary_grub-legacy : First bootloader
binary_grub-pc : Either first or extra bootloader
binary_syslinux : Either first or extra bootloader

If a bootloader is tried to be used in a role that it's not meant to be used then the build fails because that might lead to a non-bootable system.

2 files changed, 131 insertions, 3 deletions

diff --git a/functions/bootloaders.sh b/functions/bootloaders.sh
new file mode 100644
index 000000000..1898232e5
--- /dev/null
+++ b/functions/bootloaders.sh
@@ -0,0 +1,128 @@
+#!/bin/sh
+
+## live-build(7) - System Build Scripts
+## Copyright (C) 2016 Adrian Gibanel Lopez <adrian15sgd@gmail.com>
+##
+## This program comes with ABSOLUTELY NO WARRANTY; for details see COPYING.
+## This is free software, and you are welcome to redistribute it
+## under certain conditions; see COPYING for details.
+
+Is_First_Bootloader ()
+{
+	EVAL_FIRST_BOOTLOADER="${1}"
+
+	if [ "${LB_FIRST_BOOTLOADER}" = "${EVAL_FIRST_BOOTLOADER}" ]
+	then
+		return 0
+	else
+		return 1
+	fi
+
+}
+
+Is_Bootloader ()
+{
+	EVAL_BOOTLOADER="${1}"
+	OLDIFS="$IFS"
+	IFS=","
+	for BOOTLOADER in ${LB_BOOTLOADERS}
+	do
+		if [ "${BOOTLOADER}" = "${EVAL_BOOTLOADER}" ]
+		then
+			IFS="$OLDIFS"
+			return 0
+		fi
+	done
+	IFS="$OLDIFS"
+	return 1
+}
+
+Is_Extra_Bootloader ()
+{
+	EVAL_EXTRA_BOOTLOADER="${1}"
+
+	if Is_First_Bootloader "${EVAL_EXTRA_BOOTLOADER}"
+	then
+		return 1
+	else
+		if Is_Bootloader "${EVAL_EXTRA_BOOTLOADER}"
+		then
+			return 0
+		fi
+	fi
+	return 1
+
+}
+
+Check_Non_First_Bootloader ()
+{
+	NON_FIRST_BOOTLOADER="${1}"
+
+	if Is_First_Bootloader "${NON_FIRST_BOOTLOADER}"
+	then
+		Echo_error "Bootloader: ${NON_FIRST_BOOTLOADER} not supported as a first bootloader."
+		exit 1
+	else
+		return 0
+	fi
+}
+
+
+Check_Non_Extra_Bootloader ()
+{
+	NON_EXTRA_BOOTLOADER="${1}"
+
+	if Is_Extra_Bootloader "${NON_EXTRA_BOOTLOADER}"
+	then
+		Echo_error "Bootloader: ${NON_EXTRA_BOOTLOADER} not supported as a extra bootloader."
+		exit 1
+	else
+		return 0
+	fi
+}
+
+Check_First_Bootloader_Role ()
+{
+	FIRST_BOOTLOADER_ROLE="${1}"
+	Check_Non_Extra_Bootloader "${FIRST_BOOTLOADER_ROLE}"
+
+	if Is_First_Bootloader "${FIRST_BOOTLOADER_ROLE}"
+	then
+		return 0
+	else
+		exit 0
+	fi
+
+}
+
+Check_Extra_Bootloader_Role ()
+{
+	EXTRA_BOOTLOADER_ROLE="${1}"
+	Check_Non_First_Bootloader "${EXTRA_BOOTLOADER_ROLE}"
+
+	if Is_Extra_Bootloader "${EXTRA_BOOTLOADER_ROLE}"
+	then
+		return 0
+	else
+		exit 0
+	fi
+
+}
+
+Check_Any_Bootloader_Role ()
+{
+	ANY_BOOTLOADER_ROLE="${1}"
+
+	if Is_First_Bootloader "${ANY_BOOTLOADER_ROLE}"
+	then
+		return 0
+	fi
+
+	if Is_Extra_Bootloader "${ANY_BOOTLOADER_ROLE}"
+	then
+		return 0
+	fi
+
+	exit 0
+
+}
\ No newline at end of file
diff --git a/functions/defaults.sh b/functions/defaults.sh
index 334984f7b..deeaf2dc6 100755
--- a/functions/defaults.sh
+++ b/functions/defaults.sh
@@ -537,7 +537,7 @@ Set_defaults ()
 		esac
 	fi
 
-	LB_PRIMARY_BOOTLOADER=$(echo "${LB_BOOTLOADERS}" | awk -F, '{ print $1 }')
+	LB_FIRST_BOOTLOADER=$(echo "${LB_BOOTLOADERS}" | awk -F, '{ print $1 }')
 
 	# Setting checksums
 	case "${LB_MODE}" in
@@ -847,7 +847,7 @@ Check_defaults ()
 		fi
 	fi
 
-	if [ "${LB_PRIMARY_BOOTLOADER}" = "syslinux" ]
+	if [ "${LB_FIRST_BOOTLOADER}" = "syslinux" ]
 	then
 		# syslinux + fat or ntfs, or extlinux + ext[234] or btrfs
 		case "${LB_BINARY_FILESYSTEM}" in
@@ -861,7 +861,7 @@ Check_defaults ()
 
 	case "${LIVE_IMAGE_TYPE}" in
 		hdd*)
-			case "${LB_PRIMARY_BOOTLOADER}" in
+			case "${LB_FIRST_BOOTLOADER}" in
 				grub)
 					Echo_error "You have selected a combination of bootloader and image type that is currently not supported by live-build. Please use either another bootloader or a different image type."
 					exit 1