BCF-6655: Default GRUB boot entry is changed after BMR by svlv · Pull Request #86 · nable-backup/rear

Andrus Suvalau (svlv) · 2026-03-23T15:47:59Z

Save and recover grubenv

BCF-6655: Default GRUB boot entry is changed after BMR

Jira-Ref: BCF-6655: Default GRUB boot entry is changed after BMR

Copilot

Pull request overview

This PR aims to preserve the GRUB2 environment block (grubenv) across bare-metal recovery (BMR) so that the default GRUB boot entry doesn’t change after recovery.

Changes:

Add helper functions to detect grub-editenv / grub2-editenv and to detect whether GRUB2 was used.
Save grubenv values during layout/save into $VAR_DIR/recovery/grubenv.
Restore those values during finalize by re-creating/updating the target system’s GRUB environment block.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 8 comments.

File	Description
`usr/share/rear/lib/bootloader-functions.sh`	Adds `get_grub_editenv()` and `is_grub2_used()` helpers used by save/restore scripts.
`usr/share/rear/layout/save/default/700_save_grubenv.sh`	New save-stage script intended to persist `grubenv` into recovery metadata.
`usr/share/rear/finalize/Linux-i386/665_set_grubenv.sh`	New finalize-stage script intended to restore saved `grubenv` into the recovered system.

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Copilot · 2026-03-23T15:52:52Z

usr/share/rear/lib/bootloader-functions.sh

+        grub_editenv=$(chroot "$TARGET_FS_ROOT" /bin/bash -c "$cmd")
+    else
+        grub_editenv=$($cmd)


The chrooted type -P ... call relies on PATH inside the target system, but no PATH is set here. Elsewhere in the codebase chrooted type -P calls prepend PATH=/sbin:/usr/sbin:/usr/bin:/bin to avoid missing binaries. Consider doing the same here (or use run_in_chroot and set PATH in the command) so get_grub_editenv works reliably during recovery.

Suggested change

grub_editenv=$(chroot "$TARGET_FS_ROOT" /bin/bash -c "$cmd")

else

grub_editenv=$($cmd)

grub_editenv=$(chroot "$TARGET_FS_ROOT" /bin/bash -c "PATH=/sbin:/usr/sbin:/usr/bin:/bin:\$PATH; $cmd")

else

grub_editenv=$(PATH=/sbin:/usr/sbin:/usr/bin:/bin:$PATH $cmd)

Copilot · 2026-03-23T15:52:53Z

usr/share/rear/lib/bootloader-functions.sh

+    used_bootloader="$( cat "$VAR_DIR/recovery/bootloader" )"
+
+    case $used_bootloader in


is_grub2_used compares the whole contents of $VAR_DIR/recovery/bootloader against GRUB2|GRUB2-EFI. Other scripts read the first non-comment token (e.g., via an array or grep -v), which is more robust if the file contains trailing whitespace/newlines or comments. Consider normalizing to the first word / first non-comment line before the case match.

Suggested change

used_bootloader="$( cat "$VAR_DIR/recovery/bootloader" )"

case $used_bootloader in

if [[ -r "$VAR_DIR/recovery/bootloader" ]]; then

# Read the first non-comment, non-empty line and take its first token

used_bootloader=$(

grep -v '^[[:space:]]*#' "$VAR_DIR/recovery/bootloader" | \

awk 'NF { print $1; exit }'

)

fi

if [[ -z "$used_bootloader" ]]; then

return 1

fi

case "$used_bootloader" in

Copilot · 2026-03-23T15:52:53Z

usr/share/rear/layout/save/default/700_save_grubenv.sh

+    "$grub_editenv" - list > "$grubenv_file"
+    exit_code=$?
+
+    if exit_code -ne 0; then


The grub-editenv invocation looks incorrect: "$grub_editenv" - list passes - as a positional argument. grub-editenv expects list as the command (and optionally a FILE); - will be treated as a filename and can fail or read/write the wrong place. Call "$grub_editenv" list (or pass the explicit grubenv file path you intend to read).

Suggested change

"$grub_editenv" - list > "$grubenv_file"

exit_code=$?

if exit_code -ne 0; then

"$grub_editenv" list > "$grubenv_file"

exit_code=$?

if [ "$exit_code" -ne 0 ]; then

Copilot · 2026-03-23T15:52:53Z

usr/share/rear/layout/save/default/700_save_grubenv.sh

+    "$grub_editenv" - list > "$grubenv_file"
+    exit_code=$?
+
+    if exit_code -ne 0; then


This condition is a syntax error (if exit_code -ne 0; then). It should reference the variable and use a test expression (e.g., [ $exit_code -ne 0 ] or (( exit_code != 0 ))). As written, the script will fail to parse when sourced.

Suggested change

if exit_code -ne 0; then

if [ "$exit_code" -ne 0 ]; then

Copilot · 2026-03-23T15:52:54Z

usr/share/rear/finalize/Linux-i386/665_set_grubenv.sh

+
+    local grubenv_file="$VAR_DIR/recovery/grubenv"
+    if [ ! -f "$grubenv_file" ]; then
+        LogPrintError "Failed to set grubenv: '$VAR_DIR/recovery/grubenv' does not exist."


If $grubenv_file is missing you only log an error but continue; the subsequent input redirection done < "$grubenv_file" will fail and exit_code will remain 0, so the script can report success. Return non-zero (or set exit_code=1 and return) immediately when the file does not exist.

Suggested change

LogPrintError "Failed to set grubenv: '$VAR_DIR/recovery/grubenv' does not exist."

LogPrintError "Failed to set grubenv: '$VAR_DIR/recovery/grubenv' does not exist."

return 1

Copilot · 2026-03-23T15:52:54Z

usr/share/rear/finalize/Linux-i386/665_set_grubenv.sh

+    for restored_grubenv in /boot/grub2/grubenv /boot/grub/grubenv; do
+        if [ -f "$restored_grubenv" ]; then
+            rm "$restored_grubenv"
+            Log "'$restored_grubenv' was removed"
+        fi
+    done


These paths (/boot/grub2/grubenv and /boot/grub/grubenv) are checked/removed in the recovery environment, not in the restored target system. To remove grubenv from the restored filesystem, prefix with $TARGET_FS_ROOT (or run the removal via run_in_chroot). As written, it may delete the wrong file and leave the target grubenv untouched.

Copilot · 2026-03-23T15:52:54Z

usr/share/rear/finalize/Linux-i386/665_set_grubenv.sh

+    # It is essential to set up the environment block in the reserved btrfs sector
+    # See https://en.opensuse.org/GRUB#GRUB2_on_btrfs_/boot for more details
+    chroot "$TARGET_FS_ROOT" /bin/bash -c "\"$grub_editenv\" - unset dummy"
+
+    local exit_code=0
+    local var_value
+    while IFS= read -r var_value; do
+        local var="${var_value%=*}"
+        # env_block is read only
+        if [ "$var" = "env_block" ] ; then
+            continue
+        fi
+        if ! chroot "$TARGET_FS_ROOT" /bin/bash -c "\"$grub_editenv\" - set \"$var_value\""; then
+            LogPrintError "Failed to set '$var_value' to grubenv"


The chroot ... bash -c "\"$grub_editenv\" - unset dummy" / ... - set ... commands have fragile quoting and again pass - as an argument. Using run_in_chroot with a straightforward command string (and calling grub-editenv with the correct syntax and explicit grubenv file if needed) will be more reliable and easier to maintain.

Copilot · 2026-03-23T15:52:54Z

usr/share/rear/lib/bootloader-functions.sh

+    if test "$RECOVERY_MODE"; then
+        grub_editenv=$(chroot "$TARGET_FS_ROOT" /bin/bash -c "$cmd")
+    else
+        grub_editenv=$($cmd)


In non-recovery mode this runs grub_editenv=$($cmd) where cmd contains shell operators (||). Bash won’t re-parse || from an expanded variable, so this ends up calling type with literal arguments like || type -P ..., which can yield incorrect output. Use bash -c "$cmd" (or eval for this fixed string) consistently in both branches.

Suggested change

grub_editenv=$($cmd)

grub_editenv=$(bash -c "$cmd")

feat(cove): save and recover grubenv

c58e54e

Jira-Ref: BCF-6655: Default GRUB boot entry is changed after BMR

Copilot AI review requested due to automatic review settings March 23, 2026 15:48

Copilot started reviewing on behalf of Andrus Suvalau (svlv) March 23, 2026 15:48 View session

Copilot AI reviewed Mar 23, 2026

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BCF-6655: Default GRUB boot entry is changed after BMR#86

BCF-6655: Default GRUB boot entry is changed after BMR#86
Andrus Suvalau (svlv) wants to merge 1 commit intodevelopfrom
feature/BCF-6655-default-grub-boot-entry-is-changed-after-bmr

Andrus Suvalau (svlv) commented Mar 23, 2026

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		used_bootloader="$( cat "$VAR_DIR/recovery/bootloader" )"

		case $used_bootloader in

-    used_bootloader="$( cat "$VAR_DIR/recovery/bootloader" )"
-    case $used_bootloader in
+    if [[ -r "$VAR_DIR/recovery/bootloader" ]]; then
+        # Read the first non-comment, non-empty line and take its first token
+        used_bootloader=$(
+            grep -v '^[[:space:]]*#' "$VAR_DIR/recovery/bootloader" | \
+                awk 'NF { print $1; exit }'
+        )
+    fi
+    if [[ -z "$used_bootloader" ]]; then
+        return 1
+    fi
+    case "$used_bootloader" in

	LogPrintError "Failed to set grubenv: '$VAR_DIR/recovery/grubenv' does not exist."
	LogPrintError "Failed to set grubenv: '$VAR_DIR/recovery/grubenv' does not exist."
	return 1

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Andrus Suvalau (svlv) commented Mar 23, 2026

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Pull request overview

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