XS.so segfault with long directory paths

[elacour]

Server: Debian 9 /ext4
Backuppc 4.4.0
backuppc-xs 0.62
Client: Debian 9 / ext4
Method: rsync over ssh

I discovered that having a long directory path to backup on client, we have this in dmesg:

[Tue Apr 6 17:00:14 2021] BackupPC_refCou[9950]: segfault at 7ffc2ac8ea30 ip 00007fc0e8189c6b sp 00007ffc2ac8ea30 error 6 in XS.so[7fc0e8177000+25000]

I reproduced this by backuping a host name "smpl-hostname", limiting to a single directory "/p". If this directory contains 914 other subtirectories named "p" like this: "/p/p/p/p/p/...", I get the segault. with only 913 sub directories it doesn't crash.

Once a long path triggered the segfault, this one will reproduce forever for this host, even the directory has been removed.