From 6f3ed45d49f5ff53cf9e7a742a4ec2fd3426fdd2 Mon Sep 17 00:00:00 2001
From: Oliver Smith <ollieparanoid@postmarketos.org>
Date: Fri, 23 Feb 2024 01:20:27 +0100
Subject: [PATCH] systemd installs: merge /usr on chroot init (MR 2273)

---
 pmb/chroot/__init__.py |  2 +-
 pmb/chroot/init.py     | 39 ++++++++++++++++++++++++++++++++++++---
 pmb/config/__init__.py |  1 +
 pmb/config/other.py    | 11 +++++++++++
 pmb/data/merge-usr.sh  | 38 ++++++++++++++++++++++++++++++++++++++
 5 files changed, 87 insertions(+), 4 deletions(-)
 create mode 100644 pmb/config/other.py
 create mode 100644 pmb/data/merge-usr.sh

diff --git a/pmb/chroot/__init__.py b/pmb/chroot/__init__.py
index 01b50a01..8d675d54 100644
--- a/pmb/chroot/__init__.py
+++ b/pmb/chroot/__init__.py
@@ -1,6 +1,6 @@
 # Copyright 2023 Oliver Smith
 # SPDX-License-Identifier: GPL-3.0-or-later
-from pmb.chroot.init import init, init_keys
+from pmb.chroot.init import init, init_keys, UsrMerge
 from pmb.chroot.mount import mount, mount_native_into_foreign, remove_mnt_pmbootstrap
 from pmb.chroot.root import root
 from pmb.chroot.user import user
diff --git a/pmb/chroot/init.py b/pmb/chroot/init.py
index e2622ffc..104bf210 100644
--- a/pmb/chroot/init.py
+++ b/pmb/chroot/init.py
@@ -1,9 +1,10 @@
 # Copyright 2023 Oliver Smith
 # SPDX-License-Identifier: GPL-3.0-or-later
+import enum
+import filecmp
+import glob
 import logging
 import os
-import glob
-import filecmp
 
 import pmb.chroot
 import pmb.chroot.apk_static
@@ -14,6 +15,16 @@ import pmb.helpers.run
 import pmb.parse.arch
 
 
+class UsrMerge(enum.Enum):
+    """
+    Merge /usr while initializing chroot.
+    https://systemd.io/THE_CASE_FOR_THE_USR_MERGE/
+    """
+    AUTO = 0
+    ON = 1
+    OFF = 2
+
+
 def copy_resolv_conf(args, suffix="native"):
     """
     Use pythons super fast file compare function (due to caching)
@@ -74,7 +85,23 @@ def init_keys(args):
             pmb.helpers.run.root(args, ["cp", key, target])
 
 
-def init(args, suffix="native"):
+def init_usr_merge(args, suffix):
+    logging.info(f"({suffix}) merge /usr")
+    script = f"{pmb.config.pmb_src}/pmb/data/merge-usr.sh"
+    pmb.helpers.run.root(args, ["sh", "-e", script, "CALLED_FROM_PMB",
+                                f"{args.work}/chroot_{suffix}"])
+
+
+def init(args, suffix="native", usr_merge=UsrMerge.AUTO):
+    """
+    Initialize a chroot by copying the resolv.conf and updating
+    /etc/apk/repositories. If /bin/sh is missing, create the chroot from
+    scratch.
+
+    :param usr_merge: set to ON to force having a merged /usr. With AUTO it is
+                      only done if the user chose to install systemd in
+                      pmbootstrap init.
+    """
     # When already initialized: just prepare the chroot
     chroot = f"{args.work}/chroot_{suffix}"
     arch = pmb.parse.arch.from_chroot_suffix(args, suffix)
@@ -127,3 +154,9 @@ def init(args, suffix="native"):
                 pmb.chroot.root(args, ["mkdir", "-p", target], suffix)
             pmb.chroot.user(args, ["ln", "-s", target, link_name], suffix)
             pmb.chroot.root(args, ["chown", "pmos:pmos", target], suffix)
+
+    # Merge /usr
+    if usr_merge is UsrMerge.AUTO and pmb.config.is_systemd_selected(args):
+        usr_merge = UsrMerge.ON
+    if usr_merge is UsrMerge.ON:
+        init_usr_merge(args, suffix)
diff --git a/pmb/config/__init__.py b/pmb/config/__init__.py
index 587b9d5a..28b5485c 100644
--- a/pmb/config/__init__.py
+++ b/pmb/config/__init__.py
@@ -13,6 +13,7 @@ from pmb.config.load import load
 from pmb.config.save import save
 from pmb.config.merge_with_args import merge_with_args
 from pmb.config.sudo import which_sudo
+from pmb.config.other import is_systemd_selected
 
 
 #
diff --git a/pmb/config/other.py b/pmb/config/other.py
new file mode 100644
index 00000000..7a01e69d
--- /dev/null
+++ b/pmb/config/other.py
@@ -0,0 +1,11 @@
+# Copyright 2024 Oliver Smith
+# SPDX-License-Identifier: GPL-3.0-or-later
+import pmb.helpers.ui
+
+
+def is_systemd_selected(args):
+    if args.systemd == "always":
+        return True
+    if args.systemd == "never":
+        return False
+    return pmb.helpers.ui.check_option(args, args.ui, "pmb:systemd")
diff --git a/pmb/data/merge-usr.sh b/pmb/data/merge-usr.sh
new file mode 100644
index 00000000..8866e6a1
--- /dev/null
+++ b/pmb/data/merge-usr.sh
@@ -0,0 +1,38 @@
+#!/bin/sh -e
+# Copyright 2024 Oliver Smith
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+if [ "$1" != "CALLED_FROM_PMB" ]; then
+	echo "ERROR: this script is only meant to be called by pmbootstrap"
+	exit 1
+fi
+
+CHROOT="$2"
+
+test -n "$CHROOT"
+test -f "$CHROOT"/in-pmbootstrap
+
+if [ -L "$CHROOT"/bin ]; then
+	echo "ERROR: chroot has merged usr already: $CHROOT"
+	exit 1
+fi
+
+# /bin -> /usr/bin
+mv "$CHROOT"/bin/* "$CHROOT"/usr/bin/
+rmdir "$CHROOT"/bin
+ln -s usr/bin "$CHROOT"/bin
+
+# /sbin -> /usr/bin
+mv "$CHROOT"/sbin/* "$CHROOT"/usr/bin/
+rmdir "$CHROOT"/sbin
+ln -s usr/bin "$CHROOT"/sbin
+
+# /lib -> /usr/lib
+mv "$CHROOT"/lib/* "$CHROOT"/usr/lib/
+rmdir "$CHROOT"/lib
+ln -s usr/lib "$CHROOT"/lib
+
+# /usr/sbin -> /usr/bin
+mv "$CHROOT"/usr/sbin/* "$CHROOT"/usr/bin/
+rmdir "$CHROOT"/usr/sbin
+ln -s bin "$CHROOT"/usr/sbin