Holger Just and Ross West reported build issues on FreeBSD and
Solaris that were initially caused by the definition of
_XOPEN_SOURCE at the top of auth.c, which was required on Linux
to avoid a build warning.
Krzysztof Oledzki found that using _GNU_SOURCE instead also worked
on Linux and did not cause any issue on several versions of FreeBSD.
Solaris still reported a warning this time, which was fixed by
including <crypt.h>, which itself is not present on FreeBSD nor on
all Linux toolchains.
So by adding a new build option (NEED_CRYPT_H), we can get Solaris
to get crypt() working and stop complaining at the same time, without
impacting other platforms.
This fix was tested at least on several linux toolchains (at least
uclibc, glibc 2.2.5, 2.3.6 and 2.7), on FreeBSD 4 to 8, Solaris 8
(which needs crypt.h), and AIX 5.3 (without crypt.h).
Every time it builds without a warning.
Add generic authentication & authorization support.
Groups are implemented as bitmaps so the count is limited to
sizeof(int)*8 == 32.
Encrypted passwords are supported with libcrypt and crypt(3), so it is
possible to use any method supported by your system. For example modern
Linux/glibc instalations support MD5/SHA-256/SHA-512 and of course classic,
DES-based encryption.
