move mount points to a custom init and implement etc as a overlay, so the user can still change its content even with root set as read only

Co-authored-by: axtloss <[email protected]>

Author: mirkobrombin

core/integrity.go

@@ -14,6 +14,7 @@ package core
 */
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
 
@@ -25,11 +26,17 @@ type IntegrityCheck struct {
 	systemPath    string
 	standardLinks []string
 	rootPaths     []string
+	etcPaths      []string
 }
 
 // NewIntegrityCheck creates a new IntegrityCheck instance
 func NewIntegrityCheck(root ABRootPartition, repair bool) (*IntegrityCheck, error) {
 	systemPath := filepath.Join(root.Partition.MountPoint, "/.system")
+	etcPath := filepath.Join("/var/lib/abroot/etc", root.IdentifiedAs)
+	etcWorkPath := filepath.Join(
+		"/var/lib/abroot/etc",
+		fmt.Sprintf("%s-work", root.IdentifiedAs),
+	)
 	ic := &IntegrityCheck{
 		rootPath:   root.Partition.MountPoint,
 		systemPath: systemPath,
@@ -61,6 +68,10 @@ func NewIntegrityCheck(root ABRootPartition, repair bool) (*IntegrityCheck, erro
 			"/var",
 			settings.Cnf.LibPathStates,
 		},
+		etcPaths: []string{
+			etcPath,
+			etcWorkPath,
+		},
 	}
 
 	if err := ic.check(repair); err != nil {
@@ -97,6 +108,13 @@ func (ic *IntegrityCheck) check(repair bool) error {
 		}
 	}
 
+	// check if etc paths exist
+	for _, path := range ic.etcPaths {
+		if !fileExists(path) {
+			repairPaths = append(repairPaths, path)
+		}
+	}
+
 	if repair {
 		for _, path := range repairPaths {
 			PrintVerbose("IntegrityCheck: Repairing path %s", path)

core/system.go

@@ -231,7 +231,7 @@ UUID=%s  /var %s  defaults  0  0
 /var/home /home x-systemd.after=/var bind 0 0
 /var/opt /opt x-systemd.after=/var bind 0 0
 /.system/usr /.system/usr none bind,ro 0 0
-}`
+`
 	fstab := fmt.Sprintf(
 		template,
 		root.Partition.Uuid,
@@ -250,6 +250,55 @@ UUID=%s  /var %s  defaults  0  0
 	return nil
 }
 
+// GenerateSbinInit generates a usr/sbin/init file for the future root
+func (s *ABSystem) GenerateSbinInit(rootPath string, root ABRootPartition) error {
+	PrintVerbose("ABSystem.GenerateSbinInit: generating init")
+
+	template := `#!/usr/bin/bash
+echo "ABRoot: Initializing mount points..."
+
+# /var mount
+mount -U %s /var
+
+# /etc overlay
+mount -t overlay overlay -o lowerdir=/.system/etc,upperdir=/var/lib/abroot/etc/%s,workdir=/var/lib/abroot/etc/%s-work /etc
+
+# /var binds
+mount -o bind /var/home /home
+mount -o bind /var/opt /opt
+mount -o bind,ro /.system/usr /usr
+
+echo "ABRoot: Starting systemd..."
+
+# Start systemd
+exec /lib/systemd/systemd
+`
+
+	init := fmt.Sprintf(
+		template,
+		s.RootM.VarPartition.Uuid,
+		root.Label,
+		root.Label,
+	)
+
+	os.Remove(rootPath + "/usr/sbin/init")
+
+	err := ioutil.WriteFile(rootPath+"/usr/sbin/init", []byte(init), 0755)
+	if err != nil {
+		PrintVerbose("ABSystem.GenerateSbinInit:err: %s", err)
+		return err
+	}
+
+	err = os.Chmod(rootPath+"/usr/sbin/init", 0755)
+	if err != nil {
+		PrintVerbose("ABSystem.GenerateSbinInit:err(2): %s", err)
+		return err
+	}
+
+	PrintVerbose("ABSystem.GenerateSbinInit: init generated")
+	return nil
+}
+
 // Upgrade upgrades the system to the latest available image
 func (s *ABSystem) Upgrade() error {
 	PrintVerbose("ABSystem.Upgrade: starting upgrade")
@@ -353,7 +402,7 @@ func (s *ABSystem) Upgrade() error {
 		return err
 	}
 
-	// Stage 6: Generate /etc/fstab
+	// Stage 6: Generate /etc/fstab and /usr/sbin/init
 	// ------------------------------------------------
 	PrintVerbose("[Stage 6] -------- ABSystemUpgrade")
 
@@ -363,6 +412,12 @@ func (s *ABSystem) Upgrade() error {
 		return err
 	}
 
+	err = s.GenerateSbinInit(systemNew, partFuture)
+	if err != nil {
+		PrintVerbose("ABSystem.Upgrade:err(6.1): %s", err)
+		return err
+	}
+
 	// Stage 7: Update the bootloader
 	// ------------------------------------------------
 	PrintVerbose("[Stage 7] -------- ABSystemUpgrade")

samples/sbin/init

@@ -0,0 +1,19 @@
+#!/usr/bin/bash
+
+echo "ABRoot: Initializing mount points..."
+
+# /var mount
+mount -U a834618a-39a6-415a-b9a7-31d30f2db2e2 /var
+
+# /etc overlay
+mount -t overlay overlay -o lowerdir=/.system/etc,upperdir=/var/lib/abroot/etc/a,workdir=/var/lib/abroot/etc/a-work /etc
+
+# /var binds
+mount -o bind /var/home /home
+mount -o bind /var/opt /opt
+mount -o bind,ro /.system/usr /usr
+
+echo "ABRoot: Starting systemd..."
+
+# Start systemd
+exec /lib/systemd/systemd