From 8799346862285903a2348dad5e0a0cf513f8317e Mon Sep 17 00:00:00 2001
From: Richard Maw <richard.maw@codethink.co.uk>
Date: Fri, 8 Dec 2023 18:56:25 +0000
Subject: [PATCH] test: mount overlayfs over /usr in some tests

Most of the integration tests have been made to not write to /usr
but some genuinely need to do so.

Because mkosi creates images with a read-only /usr
it is not normally writeable.

By mounting an overlayfs with /usr as the lower dir
and upper and working dirs in /var tests may write to /usr.
---
 test/units/testsuite-15.sh |  5 +++++
 test/units/testsuite-26.sh |  3 +++
 test/units/testsuite-60.sh |  3 +++
 test/units/testsuite-73.sh |  3 +++
 test/units/util.sh         | 16 ++++++++++++++++
 5 files changed, 30 insertions(+)

diff --git a/test/units/testsuite-15.sh b/test/units/testsuite-15.sh
index e790b37c70d..0266f6266fb 100755
--- a/test/units/testsuite-15.sh
+++ b/test/units/testsuite-15.sh
@@ -5,6 +5,11 @@ set -o pipefail
 
 # shellcheck source=test/units/test-control.sh
 . "$(dirname "$0")"/test-control.sh
+# shellcheck source=test/units/util.sh
+. "$(dirname "$0")"/util.sh
+
+maybe_mount_usr_overlay
+trap 'maybe_umount_usr_overlay' EXIT
 
 clear_unit() {
     local unit_name="${1:?}"
diff --git a/test/units/testsuite-26.sh b/test/units/testsuite-26.sh
index 5aaac099f45..9f672c738a3 100755
--- a/test/units/testsuite-26.sh
+++ b/test/units/testsuite-26.sh
@@ -12,10 +12,13 @@ at_exit() {
         rm -fvr "/usr/lib/systemd/system/$UNIT_NAME" "/etc/systemd/system/$UNIT_NAME.d" "+4"
     fi
 
+    maybe_umount_usr_overlay
+
     rm -f /etc/init.d/issue-24990
     return 0
 }
 
+maybe_mount_usr_overlay
 trap at_exit EXIT
 
 # Create a simple unit file for testing
diff --git a/test/units/testsuite-60.sh b/test/units/testsuite-60.sh
index e800a7a12c2..3d0723e7dcc 100755
--- a/test/units/testsuite-60.sh
+++ b/test/units/testsuite-60.sh
@@ -6,6 +6,9 @@ set -o pipefail
 # shellcheck source=test/units/util.sh
 . "$(dirname "$0")"/util.sh
 
+maybe_mount_usr_overlay
+trap 'maybe_umount_usr_overlay' EXIT
+
 teardown_test_dependencies() (
     set +eux
 
diff --git a/test/units/testsuite-73.sh b/test/units/testsuite-73.sh
index df5af4ba873..3e5b78879ad 100755
--- a/test/units/testsuite-73.sh
+++ b/test/units/testsuite-73.sh
@@ -9,6 +9,9 @@ set -o pipefail
 # shellcheck source=test/units/util.sh
 . "$(dirname "$0")"/util.sh
 
+maybe_mount_usr_overlay
+trap 'maybe_umount_usr_overlay' EXIT
+
 enable_debug() {
     mkdir -p /run/systemd/system/systemd-localed.service.d
     cat >>/run/systemd/system/systemd-localed.service.d/override.conf <<EOF
diff --git a/test/units/util.sh b/test/units/util.sh
index b5ed73237c8..a18c8980cf0 100755
--- a/test/units/util.sh
+++ b/test/units/util.sh
@@ -216,3 +216,19 @@ kernel_supports_lsm() {
 
     return 1
 }
+
+MOUNTED_USR_OVERLAY=false
+
+maybe_mount_usr_overlay() {
+    if [[ ! -w /usr ]]; then
+        mkdir -p /tmp/usr-overlay/{upperdir,workdir}
+        mount -t overlay -o lowerdir=/usr,upperdir=/tmp/usr-overlay/upperdir,workdir=/tmp/usr-overlay/workdir overlay /usr
+	MOUNTED_USR_OVERLAY=true
+    fi
+}
+
+maybe_umount_usr_overlay() {
+    if "$MOUNTED_USR_OVERLAY"; then
+        umount -l /usr
+    fi
+}