getfacl truncates user and group names on ufs filesystems with POSIX acls

On a FreeBSD V12 server I ran a samba4 server with AD functionality. On
/var I use an ufs filesystem with POSIX acls, because the provisioning
step of samba4 needs this for data stored in the "sysvol" (directory
/var/db/samba4/sysvol).

The file /etc/nsswitch includes the necessary winbind entries:

   group: files winbind
   hosts: files dns
   networks: files
   passwd: files winbind
   shells: files
   services: files
   protocols: files
   rpc: files

This setup works fine with one exception: I could not backup and restore
the sysvol data with bacula. The reason for this problem is the fact:
samba needs group names with more than 32 (MAXLOGNAME - 1) bytes and
stores these names with the help of acls.

Bacula has the same program logic to read acls as getfacl(1), so I can
show the truncation problem direct:

    -> wbinfo -g | grep policy
    ADMYDOMAIN\group policy creator owners
    -> getfacl /var/db/samba4/sysvol/ad.mydomain/Policies | grep policy
    group:ADMYDOMAIN\group policy creator :rwx

The following patch for libc solves the problem for me:

--- posix1e/acl_to_text.c.orig  2017-11-25 18:12:48.000000000 +0100
+++ posix1e/acl_to_text.c       2022-01-10 19:04:05.551305000 +0100
@@ -44,6 +44,9 @@

 #include "acl_support.h"

+#undef MAXLOGNAME
+#define        MAXLOGNAME      257             /* max login name length
(incl. NUL) */
+
 /*
  * acl_to_text - generate a text form of an acl
  * spec says nothing about output ordering, so leave in acl order

The length problem exists only for POSIX acls not for nfsv4acls.
It also can be demonstrated without the help of samba4/winbind:

   echo "longestgroupnameeverintheworldandtheuniverse:*:3333:" >> /etc/group
   cd /var/tmp
   echo "ACL Test" > acltest
   setfacl -m g:longestgroupnameeverintheworldandtheuniverse:rwx acltest
   getfacl acltest

With the winbind entries in /etc/nsswitch.conf I see some messages "...
not found, and no fallback provided"
on console (in single user mode) or in debug.log (in multi user mode
before /etc/rc.d/ldconfig is
running, also from static linked programs. Some examples of programs
using e.g. getpwnam() and endpwent():

   dhclient[540]: NSSWITCH(_nsdispatch): winbind, passwd, endpwent, not
found, and no fallback provided
   pflogd[694]: NSSWITCH(_nsdispatch): winbind, passwd, endpwent, not
found, and no fallback provided
   unbound: NSSWITCH(_nsdispatch): winbind, group, setgrent, not found,
and no fallback provided
   install: NSSWITCH(_nsdispatch): winbind, passwd, setpwent, not found,
and no fallback provided

These messages should only be logged, when _NSS_DEBUG is defined for
libc. The situation looks similar to the message with comment "This gets
pretty annoying .." in the same sourcefile. Therefore I use the patch

--- nsdispatch.c.orig   2019-05-14 09:42:45.000000000 +0200
+++ nsdispatch.c        2019-11-15 11:58:16.000000000 +0100
@@ -734,10 +734,13 @@
                           (void *)srclist[i].name, ap);
                       va_end(ap);
                       st->fallback_depth = saved_depth;
-              } else
+              } else {
+#ifdef _NSS_DEBUG
                       nss_log(LOG_DEBUG, "%s, %s, %s, not found, "
                           "and no fallback provided",
                           srclist[i].name, database, method_name);
+#endif
+              }
         }
   }

Andreas