Mount overlays on top of image mount points

This allows the user to make modifications to the images that may persist
between image upgrades.

For both the system and vendor image there's a set of two overlays.
One, specified in config as "overlay", is a read-only persistent overlay
meant for stuff like installing privileged apps that should persist.
Second one, specified as "overlay-rw", is a read-write overlay that
stores the changes made by the user in case they remount the mount point
in read-write mode. This one is meant to be removed when performing
image upgrade to not carry on potentially incompatible changes between
images.

diff --git a/tools/actions/initializer.py b/tools/actions/initializer.py
index 7fec7325f2cb905daf411e0672fa7184c20c258d..31b4fc90253ca720b6a0440b3e1b426540e049a0 100644 (file)
--- a/tools/actions/initializer.py
+++ b/tools/actions/initializer.py
@@ -119,6 +119,13 @@ def init(args):
             helpers.images.get(args)
         if not os.path.isdir(tools.config.defaults["rootfs"]):
             os.mkdir(tools.config.defaults["rootfs"])
+        if not os.path.isdir(tools.config.defaults["overlay"]):
+            os.mkdir(tools.config.defaults["overlay"])
+            os.mkdir(tools.config.defaults["overlay"]+"/vendor")
+        if not os.path.isdir(tools.config.defaults["overlay_rw"]):
+            os.mkdir(tools.config.defaults["overlay_rw"])
+            os.mkdir(tools.config.defaults["overlay_rw"]+"/system")
+            os.mkdir(tools.config.defaults["overlay_rw"]+"/vendor")
         helpers.lxc.setup_host_perms(args)
         helpers.lxc.set_lxc_config(args)
         helpers.lxc.make_base_props(args)

diff --git a/tools/config/__init__.py b/tools/config/__init__.py
index 0ed3d46ffa00af9a119c1f89a43f6ef28c67b579..1edbf1761ade67fb3e09158ae7b0b563f0b102ac 100644 (file)
--- a/tools/config/__init__.py
+++ b/tools/config/__init__.py
@@ -40,6 +40,9 @@ defaults = {
 }
 defaults["images_path"] = defaults["work"] + "/images"
 defaults["rootfs"] = defaults["work"] + "/rootfs"
+defaults["overlay"] = defaults["work"] + "/overlay"
+defaults["overlay_rw"] = defaults["work"] + "/overlay_rw"
+defaults["overlay_work"] = defaults["work"] + "/overlay_work"
 defaults["data"] = defaults["work"] + "/data"
 defaults["lxc"] = defaults["work"] + "/lxc"
 defaults["host_perms"] = defaults["work"] + "/host-permissions"

diff --git a/tools/helpers/images.py b/tools/helpers/images.py
index cf65a119f40ef4b40274d0a5bae35bceb0e49428..e00e9b1f43359f955d5cabae0184a064c3de964e 100644 (file)
--- a/tools/helpers/images.py
+++ b/tools/helpers/images.py
@@ -128,8 +128,19 @@ def make_prop(args, cfg, full_props_path):
 def mount_rootfs(args, images_dir, session):
     helpers.mount.mount(args, images_dir + "/system.img",
                         tools.config.defaults["rootfs"], umount=True)
+    helpers.mount.mount_overlay(args, [tools.config.defaults["overlay"],
+                                       tools.config.defaults["rootfs"]],
+                                tools.config.defaults["rootfs"],
+                                upper_dir=tools.config.defaults["overlay_rw"] + "/system",
+                                work_dir=tools.config.defaults["overlay_work"] + "/system")
     helpers.mount.mount(args, images_dir + "/vendor.img",
                            tools.config.defaults["rootfs"] + "/vendor")
+    helpers.mount.mount_overlay(args, [tools.config.defaults["overlay"] + "/vendor",
+                                       tools.config.defaults["rootfs"] + "/vendor"],
+                                tools.config.defaults["rootfs"] + "/vendor",
+                                upper_dir=tools.config.defaults["overlay_rw"] + "/vendor",
+                                work_dir=tools.config.defaults["overlay_work"] + "/vendor")
+
     for egl_path in ["/vendor/lib/egl", "/vendor/lib64/egl"]:
         if os.path.isdir(egl_path):
             helpers.mount.bind(

diff --git a/tools/helpers/mount.py b/tools/helpers/mount.py
index 2660952696a156b2b0e266be58feb6098c12baf5..a0d34be5d8a8d6e1f0614ac88ae45bd7a39762d8 100644 (file)
--- a/tools/helpers/mount.py
+++ b/tools/helpers/mount.py
@@ -149,3 +149,28 @@ def mount(args, source, destination, create_folders=True, umount=False,
     # Verify, that it has worked
     if not ismount(destination):
         raise RuntimeError("Mount failed: " + source + " -> " + destination)
+
+def mount_overlay(args, lower_dirs, destination, upper_dir=None, work_dir=None,
+                  create_folders=True, readonly=True):
+    """
+    Mount an overlay.
+    """
+    dirs = [*lower_dirs]
+    options = ["xino=off", "lowerdir=" + (":".join(lower_dirs))]
+
+    if upper_dir:
+        dirs.append(upper_dir)
+        dirs.append(work_dir)
+        options.append("upperdir=" + upper_dir)
+        options.append("workdir=" + work_dir)
+
+    for dir_path in dirs:
+        if not os.path.exists(dir_path):
+            if create_folders:
+                tools.helpers.run.user(args, ["mkdir", "-p", dir_path])
+            else:
+                raise RuntimeError("Mount failed, folder does not exist: " +
+                                   dir_path)
+
+    mount(args, "overlay", destination, mount_type="overlay", options=options,
+          readonly=readonly, create_folders=create_folders, force=True)