bootloader: Reject initrd without kernel

Fail when parsing a menu entry that specifies an initrd without a
preceding kernel since it is invalid according to GRUB2.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>

Author: rosslagerwall

tests/data/grub-linux-no-kernel.cfg

@@ -0,0 +1,3 @@
+menuentry 'Linux - Safe Mode' {
+	initrd /boot/initrd.img-1
+}

tests/test_bootloader.py

@@ -29,7 +29,6 @@ def test_no_multiboot(self):
         # A module2 line without a multiboot2 line is an error
         with self.assertRaises(RuntimeError):
             Bootloader.readGrub2("tests/data/grub-no-multiboot.cfg")
-
 class TestLinuxBootloader(unittest.TestCase):
     def setUp(self):
         self.tmpdir = mkdtemp(prefix="testbl")
@@ -73,6 +72,12 @@ def test_grub2_newdefault(self):
         assert bl.menu["safe"].kernel_args == "ro"
         assert bl.menu["safe"].initrd == "/boot/initrd.img-2"
 
+    def test_no_kernel(self):
+        # An initrd line without a kernel line is an error
+        with self.assertRaises(RuntimeError):
+            Bootloader.readGrub2("tests/data/grub-linux-no-kernel.cfg")
+
+
 class TestBootloaderAdHoc(unittest.TestCase):
     def setUp(self):
         self.bl = Bootloader.readGrub2("tests/data/grub.cfg")

xcp/bootloader.py

@@ -203,6 +203,8 @@ def parse_boot_entry(line):
                     elif l.startswith("linux"):
                         kernel, kernel_args = parse_boot_entry(l)
                     elif l.startswith("initrd"):
+                        if not kernel:
+                            raise RuntimeError("Need a kernel")
                         initrd = l.split(None, 1)[1]
                     elif l.startswith("search --label --set root"):
                         root = l.split()[4]