[PATCH] util/grub.d/30_os-prober.in: Fix GRUB_OS_PROBER_SKIP_LIST for non-EFI

From: Pascal Hambourg <pascal@plouf.fr.eu.org>
To: grub-devel@gnu.org
Subject: [PATCH] util/grub.d/30_os-prober.in: Fix GRUB_OS_PROBER_SKIP_LIST for non-EFI
Date: Fri, 19 Jan 2024 11:28:55 +0100	[thread overview]
Message-ID: <71538fee-34e5-4d4a-81b5-91bcf5d1b08b@plouf.fr.eu.org> (raw)

GRUB documentation states:

'GRUB_OS_PROBER_SKIP_LIST'
  List of space-separated FS UUIDs of filesystems to be ignored from
  os-prober output. For efi chainloaders it's <UUID>@<EFI FILE>

But the actual behaviour does not match this description. Setting

  GRUB_OS_PROBER_SKIP_LIST="<UUID>"

does not ignore non-EFI boot loaders detected on filesystem <UUID>.
In order to skip non-EFI boot loaders, you must set

  GRUB_OS_PROBER_SKIP_LIST="<UUID>@<DEVICE>"

which is both absurd (UUID and device are redundant) and wrong
(device names such as /dev/sd* may not be persistent across boots).

This patch fixes the detection of "@<EFI FILE>" in the device string
reported by os-prober.

Fixes: 55e706c9 (Add GRUB_OS_PROBER_SKIP_LIST to selectively skipping systems)

Note: the UUID matching regex uses word boundaries '\b' but '@' is
not a word character. As a consequence, setting

  GRUB_OS_PROBER_SKIP_LIST="<UUID>@<ANYTHING>"

will ignore non-EFI boot loaders detected on filesystem <UUID> even
though the goal is to ignore a given EFI boot loader only.
However I think this is desirable to preserve the behaviour of
existing setups which use GRUB_OS_PROBER_SKIP_LIST="<UUID>@<DEVICE>".

Signed-off-by: Pascal Hambourg <pascal@plouf.fr.eu.org>
---
 util/grub.d/30_os-prober.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util/grub.d/30_os-prober.in b/util/grub.d/30_os-prober.in
index e9e217208..a24c01334 100644
--- a/util/grub.d/30_os-prober.in
+++ b/util/grub.d/30_os-prober.in
@@ -125,7 +125,7 @@ for OS in ${OSPROBED} ; do
   if UUID="`${grub_probe} --target=fs_uuid --device ${DEVICE%@*}`"; then
     EXPUUID="$UUID"
 
-    if [ x"${DEVICE#*@}" != x ] ; then
+    if [ x"${DEVICE%@*}" != x"${DEVICE}" ] ; then
       EXPUUID="${EXPUUID}@${DEVICE#*@}"
     fi
 
-- 
2.30.2

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