From 1a493f9beefd527a988c54627b348e530a8d60c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fredrik=20L=C3=B6nnegren?= <fredrik.lonnegren@suse.com>
Date: Wed, 21 Feb 2024 15:24:50 +0100
Subject: [PATCH] Use backup legacy grub.cfg location
MIME-Version: 1.0
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If the new /etc/elemental/grub.cfg config is not found, revert to using
/etc/cos/grub.cfg for backwards compatibility.

Signed-off-by: Fredrik Lönnegren <fredrik.lonnegren@suse.com>
---
 pkg/bootloader/grub.go     | 40 ++++++++++++++++++++++++--------------
 pkg/constants/constants.go |  1 +
 2 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/pkg/bootloader/grub.go b/pkg/bootloader/grub.go
index d8e2a3c8dce..4b55091354b 100644
--- a/pkg/bootloader/grub.go
+++ b/pkg/bootloader/grub.go
@@ -19,6 +19,7 @@ package bootloader
 import (
 	"bytes"
 	"fmt"
+	"os"
 	"path/filepath"
 	"regexp"
 
@@ -57,12 +58,13 @@ type Grub struct {
 	grubEfiImg string
 	mokMngr    string
 
-	grubPrefixes     []string
-	configFile       string
-	elementalCfg     string
-	disableBootEntry bool
-	clearBootEntry   bool
-	secureBoot       bool
+	grubPrefixes       []string
+	configFile         string
+	elementalCfg       string
+	legacyElementalCfg string
+	disableBootEntry   bool
+	clearBootEntry     bool
+	secureBoot         bool
 }
 
 var _ v1.Bootloader = (*Grub)(nil)
@@ -76,15 +78,16 @@ func NewGrub(cfg *v1.Config, opts ...GrubOptions) *Grub {
 		secureBoot = false
 	}
 	g := &Grub{
-		fs:             cfg.Fs,
-		logger:         cfg.Logger,
-		runner:         cfg.Runner,
-		platform:       cfg.Platform,
-		configFile:     grubCfgFile,
-		grubPrefixes:   defaultGrubPrefixes,
-		elementalCfg:   filepath.Join(constants.GrubCfgPath, constants.GrubCfg),
-		clearBootEntry: true,
-		secureBoot:     secureBoot,
+		fs:                 cfg.Fs,
+		logger:             cfg.Logger,
+		runner:             cfg.Runner,
+		platform:           cfg.Platform,
+		configFile:         grubCfgFile,
+		grubPrefixes:       defaultGrubPrefixes,
+		elementalCfg:       filepath.Join(constants.GrubCfgPath, constants.GrubCfg),
+		legacyElementalCfg: filepath.Join(constants.LegacyGrubCfgPath, constants.GrubCfg),
+		clearBootEntry:     true,
+		secureBoot:         secureBoot,
 	}
 
 	for _, o := range opts {
@@ -413,6 +416,13 @@ func (g *Grub) Install(rootDir, bootDir string) (err error) {
 func (g Grub) InstallConfig(rootDir, bootDir string) error {
 	for _, path := range g.grubPrefixes {
 		grubFile := filepath.Join(rootDir, g.elementalCfg)
+		if _, err := os.Stat(grubFile); err != nil {
+			if os.IsNotExist(err) {
+				grubFile = filepath.Join(rootDir, g.legacyElementalCfg)
+				g.logger.Warnf("Grub config not found, using legacy config: %s", grubFile)
+			}
+		}
+
 		dstGrubFile := filepath.Join(bootDir, path, g.configFile)
 
 		g.logger.Infof("Using grub config file %s", grubFile)
diff --git a/pkg/constants/constants.go b/pkg/constants/constants.go
index 29cadfac95d..79ddc93edaf 100644
--- a/pkg/constants/constants.go
+++ b/pkg/constants/constants.go
@@ -182,6 +182,7 @@ const (
 	LegacyPassivePath = LegacyImagesPath + "/passive.img"
 	LegacyActivePath  = LegacyImagesPath + "/active.img"
 	LegacyStateDir    = "/run/initramfs/cos-state"
+	LegacyGrubCfgPath = "/etc/cos"
 )
 
 // GetDefaultSystemEcludes returns a list of transient paths