fix: bootloader update logic

usr/lib/akshara/utils/update.py

@@ -35,6 +35,7 @@ def update_cleanup() -> None:
             "-rf",
             "/var/cache/akshara/rootfs",
             "/.update_rootfs",
+            "/.boot.bkp",
         ]
     )
 
@@ -143,86 +144,116 @@ def merge_var(new_rootfs: RootFS, overrides_keep_new: dict) -> None:
                 )
 
 
-def handle_boot(new_rootfs, boot_config) -> None:
+def merge_into_tree(tree_root: str, tmp_tree_root: str) -> None:
+    """Merge a new tree into an existing tree.
+
+    Args:
+        tree_root: String containing path to existing tree.
+        tmp_tree_root: String containing path to new tree.
+    """
+
+    new_paths = []
+    for tmp_root, _, files in os.walk(tmp_tree_root):
+        root = tmp_root.replace(tmp_tree_root, tree_root, 1)
+        subprocess.run(["mkdir", "-p", root])
+        new_paths.append(root)
+        for path in files:
+            subprocess.run(["rm", "-rf", "--", os.path.join(root, path)])
+            subprocess.run(
+                [
+                    "cp",
+                    "-ax",
+                    os.path.join(tmp_root, path),
+                    os.path.join(root, path),
+                ]
+            )
+            new_paths.append(os.path.join(root, path))
+
+    for root, _, files in os.walk(tree_root):
+        for path in files:
+            if os.path.join(root, path) not in new_paths:
+                subprocess.run(["rm", "-rf", "--", os.path.join(root, path)])
+
+
+def handle_boot(new_rootfs: RootFS, boot_config: dict) -> None:
     """Handles /boot partition."""
 
-    subprocess.run(["rm", "-rf", "/.tmp.boot"])
+    subprocess.run(["rm", "-rf", "/.boot.bkp"])
-    subprocess.run(["cp", "-ax", os.path.join(str(new_rootfs), "boot"), "/.tmp.boot"])
+    subprocess.run(["cp", "-ax", "/boot", "/.boot.bkp"])
+
+    # Replace contents of /boot with those from new rootfs
+    # FIXME: should be atomic
+    merge_into_tree("/boot", os.path.join(str(new_rootfs), "boot"))
+
+    subprocess.run(["mount", "--bind", "/boot", f"{new_rootfs}/boot"])
+
+    def restore_old_boot():
+        subprocess.run(
+            ["umount", "-l", f"{new_rootfs}/boot"],
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+        )
+        merge_into_tree("/boot", "/.boot.bkp")
 
     if boot_config["type"] == "bios":
         if boot_config["loader"] == "grub":
             if (
-                subprocess.run(
+                new_rootfs.exec_chroot(
                     [
                         "grub-install",
-                        f"--directory={os.path.join(str(new_rootfs), 'usr/lib/grub/i386-pc')}",
-                        "--boot-directory=/.tmp.boot",
                         "--target=i386-pc",
                         boot_config["device"],
                     ]
                 ).returncode
                 != 0
             ):
-                output.error("aborting update...")
+                restore_old_boot()
-                subprocess.run(["rm", "-rf", "/.tmp.boot"])
                 output.error("failed to install GRUB")
+                output.error("aborted update")
                 exit(1)
         else:
-            subprocess.run(["umount", "-l", "/boot"])
+            restore_old_boot()
-            subprocess.run(["rm", "-rf", "/.tmp.boot"])
             output.error("unsupported bootloader for BIOS configuration")
+            output.error("aborted update")
             exit(1)
     elif boot_config["type"] == "uefi":
         if boot_config["loader"] == "grub":
             if (
-                subprocess.run(
+                new_rootfs.exec_chroot(
                     [
                         "grub-install",
-                        f"--directory={os.path.join(str(new_rootfs), 'usr/lib/grub/x86_64-efi')}",
+                        "--efi-directory=/boot",
-                        "--efi-directory=/.tmp.boot",
-                        "--boot-directory=/.tmp.boot",
                         "--target=x86_64-efi",
                         "--removable",
                         "--bootloader-id=blendOS",
                     ]
-                )
+                ).returncode
                 != 0
             ):
-                output.error("aborting update...")
+                restore_old_boot()
-                subprocess.run(["rm", "-rf", "/.tmp.boot"])
                 output.error("failed to install GRUB")
+                output.error("aborted update")
                 exit(1)
         else:
-            subprocess.run(["rm", "-rf", "/.tmp.boot"])
+            restore_old_boot()
             output.error("unsupported bootloader for BIOS configuration")
+            output.error("aborted update")
             exit(1)
     else:
-        subprocess.run(["umount", "-l", "/boot"])
+        restore_old_boot()
-        subprocess.run(["rm", "-rf", "/.tmp.boot"])
         output.error(f"unsupported system type - {boot_config['type']}")
+        output.error("aborted update")
         exit(1)
 
     if boot_config["loader"] == "grub":
-        new_rootfs.exec_chroot(["grub-mkconfig", "-o", "/grub.cfg"])
+        new_rootfs.exec_chroot(["grub-mkconfig", "-o", "/boot/grub/grub.cfg"])
-        subprocess.run(["cp", f"{new_rootfs}/grub.cfg", "/.tmp.boot/grub/grub.cfg"])
 
-    # Replace /boot with /.tmp.boot
+    subprocess.run(
-    # FIXME: should be atomic
+        ["umount", "-l", f"{new_rootfs}/boot"],
-    for tmp_boot, dirs, files in os.walk("/.tmp.boot"):
+        stdout=subprocess.DEVNULL,
-        boot = tmp_boot.replace("/.tmp.boot", "/boot", 1)
+        stderr=subprocess.DEVNULL,
-        subprocess.run(["mkdir", "-p", boot])
+    )
-        for path in dirs + files:
+    subprocess.run(["rm", "-rf", "/.boot.bkp"])
-            subprocess.run(["rm", "-rf", "--", os.path.join(boot, path)])
-            subprocess.run(
-                [
-                    "cp",
-                    "-ax",
-                    os.path.join(tmp_boot, path),
-                    os.path.join(boot, path),
-                ]
-            )
-
-    subprocess.run(["rm", "-rf", "/.tmp.boot"])
 
 
 def update() -> None: