Can't get ID for group with large number of users when using 'fileGroup' parameter

[emilbart]

rsyslogd complains when in action we set to 'fileGroup' parameter the name of group with large number of users.

The problem is in function doGetGID where getgrnam_r is called. The buffer with not enough size is passed to getgrnam_r.

Expected behavior

rsyslog should find ID for group with large number of users when using 'fileGroup' parameter in rainerscript configuration.

Actual behavior

The rsyslog complains with the following messages:
parameter 'filegroup': error to obtaining group id for 'students': Numerical result out of range [v8.32.0]
error during parsing file /etc/rsyslog.d/test.conf, on or before line 1: parameter 'filegroup': ID for group students could not be found [v8.32.0 try http://www.rsyslog.

Steps to reproduce the behavior

1. Create a group with large number of users. For example assign to group at least 200 user.
2. Create file /etc/rsyslog.d/test.conf with the following body:
   *.* action(type="omfile" FileCreateMode="0644" fileOwner="student1" fileGroup="students" File="/tmp/logging")
3. Run rsyslogd.

Environment

rsyslogd -v
rsyslogd 8.32.0, compiled with:
PLATFORM: x86_64-pc-linux-gnu
PLATFORM (lsb_release -d):
FEATURE_REGEXP: Yes
GSSAPI Kerberos 5 support: Yes
FEATURE_DEBUG (debug build, slow code): No
32bit Atomic operations supported: Yes
64bit Atomic operations supported: Yes
memory allocator: system default
Runtime Instrumentation (slow code): No
uuid support: Yes
systemd support: Yes
Number of Bits in RainerScript integers: 64

See http://www.rsyslog.com for more information.