From 9775c0da2eb2da22ec15c073c3d53a324f62e59a Mon Sep 17 00:00:00 2001
From: Alan <alan.martinovic@northern.tech>
Date: Tue, 18 Feb 2025 18:57:03 +0100
Subject: [PATCH] feat: warn for signs of external  mender installation

mender-convert doesn't handle well if the input image has Mender
installed already.
This could happen if someone did the installation of the Debian Mender package
and then attempted to mender-convert that image.

This introduces a function that will detect detect the potential issue
to aid troubleshooting from the logs once the error is hit.

With it you will see:

```
2025-02-18 18:06:44 [WARN] [mender-convert-modify] work/rootfs/var/lib/mender-monitor exists!
2025-02-18 18:06:44 [WARN] [mender-convert-modify] Input image contain traces Mender of previous Mender installation
2025-02-18 18:06:44 [WARN] [mender-convert-modify] The conversion might fail. Please provide a clean input image.

Extra WARN context is above
Below is old

2025-02-18 17:53:29 [INFO] [mender-convert-modify] Performing platform specific pre-modifications (if any)
2025-02-18 17:53:29 [INFO] [mender-convert-modify] Running hook: platform_pre_modify
2025-02-18 17:53:29 [INFO] [mender-convert-modify] Creating state folder in the data partition for Mender  add-ons
mender-convert-modify has finished. Cleaning up...
2025-02-18 17:53:29 [ERROR] [mender-convert] mender-convert failed
2025-02-18 17:53:29 [DEBUG] [mender-convert-modify] When running: (./mender-convert-modify:174): run_and_
log_cmd():

        sudo ln -sf /data/mender work/rootfs/var/lib
        ln: work/rootfs/var/lib/mender: cannot overwrite directory

2025-02-18 17:53:29 [ERROR] [mender-convert] mender-convert failed
2025-02-18 17:53:29 [ERROR] [mender-convert] mender-convert exit code: 1
```

Changelog: title
Ticket: none

Signed-off-by: Alan <alan.martinovic@northern.tech>
---
 mender-convert-modify |  2 ++
 modules/probe.sh      | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/mender-convert-modify b/mender-convert-modify
index cec4c58a90..60bb0e3c46 100755
--- a/mender-convert-modify
+++ b/mender-convert-modify
@@ -103,6 +103,8 @@ mkdir -p work/rootfs
 sudo mount ${boot_part} work/boot
 sudo mount ${root_part} work/rootfs
 
+probe_untainted_rootfs_input
+
 if [ -z "${MENDER_DEVICE_TYPE}" ]; then
     # Observed systems who do not have this file, e.g images generated with mkosi
     if [ -f work/rootfs/etc/hostname ]; then
diff --git a/modules/probe.sh b/modules/probe.sh
index 0bdab40e26..782694569f 100644
--- a/modules/probe.sh
+++ b/modules/probe.sh
@@ -13,6 +13,29 @@
 #    See the License for the specific language governing permissions and
 #    limitations under the License.
 
+# Checks there is no preexisting mender integration on the golden image
+#
+# mender-convert expects a vanilla image wihtout mender installed by other means.
+# If you provide as input an image that has mender installed by other means already
+# it might fail.
+# This function will just print warnings for traces of things that look like a tainted input image
+probe_untainted_rootfs_input() {
+    # None of these should be present in a clean rootfs
+    directories=(
+        "work/rootfs/var/lib/mender-monitor"
+        "work/rootfs/var/lib/mender-configure"
+        "work/data/mender"
+    )
+
+    for dir in "${directories[@]}"; do
+        if [ -e "$dir" ]; then
+            log_warn "$dir exists!"
+            log_warn "Input image contain traces Mender of previous Mender installation"
+            log_warn "The conversion might fail. Please provide a clean input image."
+        fi
+    done
+}
+
 # Prints target architecture
 #
 # No input parameters and these work on the assumption that boot and root parts