snap-sync --sudo: "rsync: mkstemp failed: Permission denied (13)"

[Zoddo]

Trying to do the initial backup of my root subvol with the following command...

sudo snap-sync -r storage --sudo

...produced the following error:

...
Performing backups...

Sending first snapshot for 'root' configuration...
At subvol //.snapshots/298/snapshot
7,88GiO 2:15:33 [1016KiB/s] [                                                                                            <=>                                            ]
rsync: mkstemp "/home/zoddo/LAPTOP_BACKUP/root/298/.info.xml.stGXBy" failed: Permission denied (13)
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1330) [sender=v3.2.3]
Exited due to error on line 501.
exit status: 23
command: rsync -avzq "$new_info" "$remote":"$backup_location"
bash line: 0
function name: 

The remote name storage is an alias defined in /root/.ssh/config, which also forces the username zoddo, hence the use of --sudo.

As I understand, it tried to rsync the file with the remote user zoddo, but it didn't had the permission because the parent directory was created by root (through sudo).

I think this can be fixed by something like rsync --rsync-path="sudo rsync", but maybe there is a better way.

[Zoddo]

I managed to fix the issue with the following change:

--- /usr/bin/snap-sync	2021-01-30 09:37:09.000000000 +0100
+++ ./snap-sync	2021-06-02 13:56:40.222397205 +0200
@@ -497,10 +497,15 @@
     if [[ -z $remote ]]; then
         cp "$new_info" "$backup_location"
     else
+        remote_rsync="rsync"
+        if [[ $sudo -eq 1 ]]; then
+            remote_rsync="sudo rsync"
+        fi
+
         if [[ -z $port ]]; then
-            rsync -avzq "$new_info" "$remote":"$backup_location"
+            rsync -avzq --rsync-path="$remote_rsync" "$new_info" "$remote":"$backup_location"
         else
-            rsync -avzqe "ssh -p $port" "$new_info" "$remote":"$backup_location"
+            rsync -avzqe "ssh -p $port" --rsync-path="$remote_rsync" "$new_info" "$remote":"$backup_location"
         fi
     fi
 

I'm not a bash expert, there is probably a cleaner way to do this.