Factor out grub-related diversions and use them consistently, so we

don't end up with wrong os-probe output in our grub.cfg.

debian/changelog

@@ -32,6 +32,8 @@ livecd-rootfs (2.408.19) xenial; urgency=medium
     - If we're using SUBPROJECT=minimized, and tzdata is not installed,
       remove files that have been left behind.  This is a workaround for a
       bug that should be fixed in tzdata.
+  * Factor out grub-related diversions and use them consistently, so we
+    don't end up with wrong os-probe output in our grub.cfg.
 
   [ Balint Reczey ]
   * Mount using --make-rslave to ensure safe unmounts for rbind mounts

live-build/ubuntu-cpc/functions

@@ -281,3 +281,32 @@ replace_grub_root_with_label() {
     sed -i -e "s,root=[^ ]\+,root=LABEL=cloudimg-rootfs," \
         "$CHROOT_ROOT/boot/grub/grub.cfg"
 }
+
+
+# When running update-grub in a chroot on a build host, we don't want it to
+# probe for disks or probe for other installed OSes.  Extract common
+# diversion wrappers, so this isn't reinvented differently for each image.
+divert_grub() {
+	CHROOT_ROOT="$1"
+
+	chroot "$CHROOT_ROOT" dpkg-divert --local \
+		--rename /usr/sbin/grub-probe
+	chroot "$CHROOT_ROOT" touch /usr/sbin/grub-probe
+	chroot "$CHROOT_ROOT" chmod +x /usr/sbin/grub-probe
+
+	chroot "$CHROOT_ROOT" dpkg-divert --local \
+		--divert /etc/grub.d/30_os-prober.dpkg-divert \
+		--rename /etc/grub.d/30_os-prober
+}
+
+undivert_grub() {
+	CHROOT_ROOT="$1"
+
+	chroot "$CHROOT_ROOT" rm /usr/sbin/grub-probe
+	chroot "$CHROOT_ROOT" dpkg-divert --remove --local \
+		--rename /usr/sbin/grub-probe
+
+	chroot "$CHROOT_ROOT" dpkg-divert --remove --local \
+		--divert /etc/grub.d/30_os-prober.dpkg-divert \
+		--rename /etc/grub.d/30_os-prober
+}

live-build/ubuntu-cpc/hooks/032-disk-image.binary

@@ -120,7 +120,9 @@ if [ "${should_install_grub}" -eq 1 ]; then
 		echo "partuuid found for root device; forcing it in Grub"
 		mkdir -p mountpoint/etc/default/grub.d
 		echo "GRUB_FORCE_PARTUUID=$partuuid" >> mountpoint/etc/default/grub.d/40-force-partuuid
+		divert_grub mountpoint
 		chroot mountpoint update-grub
+		undivert_grub mountpoint
 	fi
 fi
 

live-build/ubuntu-cpc/hooks/033-disk-image-uefi.binary

@@ -119,10 +119,10 @@ EOF
         chroot mountpoint grub-install --target=i386-pc "${loop_device}"
     fi
 
-    chroot mountpoint dpkg-divert --local --rename /etc/grub.d/30_os-prober
+    divert_grub mountpoint
     chroot mountpoint update-grub
     replace_grub_root_with_label mountpoint
-    chroot mountpoint dpkg-divert --remove --local --rename /etc/grub.d/30_os-prober
+    undivert_grub mountpoint
 
     chroot mountpoint apt-get -y clean
 

live-build/ubuntu-cpc/hooks/034-disk-image-ppc64el.binary

@@ -50,10 +50,10 @@ EOF
         --boot-directory=/boot \
         --target=powerpc-ieee1275
 
-    chroot mountpoint dpkg-divert --local --rename /etc/grub.d/30_os-prober
+    divert_grub mountpoint
     chroot mountpoint update-grub
     replace_grub_root_with_label mountpoint
-    chroot mountpoint dpkg-divert --remove --local --rename /etc/grub.d/30_os-prober
+    undivert_grub mountpoint
 
     umount_partition mountpoint
     rmdir mountpoint