lib/48859: getnetgrent(3) doesn't work with 3rd party NSS modules

[tron%zhadum.org.uk@localhost]

>Number:         48859
>Category:       lib
>Synopsis:       getnetgrent(3) doesn't work with 3rd party NSS modules
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat May 31 17:20:00 +0000 2014
>Originator:     tron%zhadum.org.uk@localhost
>Release:        NetBSD 6.99.43 (2014-05-28 HEAD sources)
>Organization:
Matthias Scheler                                 https://zhadum.org.uk/
>Environment:
System: NetBSD lyssa.zhadum.org.uk 6.99.43 NetBSD 6.99.43 (GENERIC) #0: Wed May 
28 21:59:52 BST 2014 
tron%lyssa.zhadum.org.uk@localhost:/src/sys/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:
NetBSD's libc fails to use the netgroup backend implemented by 3rd party
NSS modules which were written for Solaris or Linux.

>How-To-Repeat:
1.) Install "pkgsrc/databases/nss_ldap" and configure it appropriately.

2.) Configure "netgroup" lookups via LDAP in "/etc/nsswitch.conf"
    e.g. with a line like this:

netgroup:       files ldap

3.) Try to look-up a netgroup with "getent netgroup <name>".

"getent" will *not* print out the netgroup. It will in fact not even
communicate with the LDAP server to get information about the netgroup.

The problem is that our "libc" looks for a symbol called
"_nss_<module>_getnetgrent". But modules written for Linux or Solaris
only provide "_nss_<module>_getnetgrent_r".

>Fix:
We should probably implement getnetgrent_r(3) which dispatches to NSS.
Here is the signature from the Linux manual page ...

       int getnetgrent_r(char **host, char **user,
                         char **domain, char *buf, int buflen);

... and from the Solaris manual page:

     int  getnetgrent_r(char  **machinep,  char   **userp,   char
     **domainp, char *buffer, int buflen);

The existing function getnetgrent(3) should be implemented via
getnetgrent_r(3).