Merge ~jocave/plainbox-provider-resource:bootloader-error-handling into plainbox-provider-resource:master

[Jonathan Cave]

Improve bootloader_resource.py when running on classic systems and when the BOOT_IMAGE variable does not contain a bracketed variable.

[Sylvain Pineau (sylvain-pineau)]

(11:27:53 AM) spineau: joc: how can I test it, just classic?
(11:31:55 AM) spineau: joc: '(hd1,gpt1)' looks a bit restrictive. could we wee a system with for example hd0, gpt2 ?
(11:32:03 AM) spineau: wee/see
(11:32:18 AM) joc: i have no idea
(11:32:27 AM) joc: this is a question for the delivery team i think
(11:35:47 AM) spineau: joc: I'm ok to land and revisit the rule when a new project will come and fail with an 'unknown' grub_path. If it solves fortknox that's already an improvement

[Sylvain Pineau (sylvain-pineau)]

+1

review: Approve

diff --git a/bin/bootloader_resource.py b/bin/bootloader_resource.py
index dd9b995..5088218 100755
--- a/bin/bootloader_resource.py
+++ b/bin/bootloader_resource.py
@@ -52,7 +52,23 @@ def booted_kernel_location(bl_name):
             cmdline = f.readline()
         result = parse_kernel_cmdline(cmdline)
         grub_path = result.params['BOOT_IMAGE']
-        path = os.path.join('/boot/efi', grub_path[grub_path.index(')')+2:])
+
+        # The BOOT_IMAGE parameter is tricky to decipher. It can be absolute
+        # path or refer or contain a variable expanded by ... initramfs?
+        if os.path.isabs(grub_path):
+            path = grub_path
+        else:
+            try:
+                # if we know where the parameter is referencing, replace it
+                if '(loop)' in grub_path:
+                    # implies of out of the kernel snap (so no FDE)
+                    pass
+                elif '(hd1,gpt1)' in grub_path:
+                    # used by fortknox
+                    path = os.path.join(
+                        '/boot/efi', grub_path[grub_path.index(')')+2:])
+            except ValueError:
+                pass
     elif bl_name == 'androidboot':
         pass
     elif bl_name == 'lk':