multiline filenames are not backuped

[Al-]

Filenames that contain linebreaks are not included in the backups:

$ ls mul*
'multiline'$'\n''filename'
$ ls mul* | hexdump -C
00000000  6d 75 6c 74 69 6c 69 6e  65 0a 66 69 6c 65 6e 61  |multiline.filena|
00000010  6d 65 0a                                          |me.|
00000013

Output from backup2l:

...
Creating archive using 'DRIVER_TAR_GZ'...
  tar: filename: Cannot stat: No such file or directory
  tar: /home/xxx/xxx/xxx/multiline: Cannot stat: No such file or directory
...
  < filename
  < /home/xxx/xxx/xxx/multiline

It does not seem to be a limitation of tar (albeit the error message seems to imply), as tar can process this file:

$ tar --create --file /tmp/testtar.tar.gz ./multi*
$ tar --list --file /tmp/testtar.tar.gz
./multiline\nfilename

My system:

• Linux xxx 5.8.0-48-generic #54~20.04.1-Ubuntu SMP Sat Mar 20 13:40:25 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
• backup2l v1.6 by Gundolf Kiefer
• stat (GNU coreutils) 8.30
• tar (GNU tar) 1.30

[gkiefer]

To fix this, a careful review of all quotations in the code and testing is necessary.

Patches are welcome!