Abstract how to look up user password to be more flexible

This adds user_password() to abstract how the user's password is looked
up.  If spwd is not available, this will read the shadow file for the
user's shadow entry.  This will then facilitate idempotent password
changes on hosts without spwd.

library/user

@@ -18,6 +18,7 @@
 # You should have received a copy of the GNU General Public License
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
 
+import os
 import pwd
 import grp
 try:
@@ -26,6 +27,14 @@ try:
 except:
     HAVE_SPWD=False
 
+SHADOWFILE = '/etc/shadow'
+if os.path.exists('/etc/master.passwd'):
+    SHADOWFILE = '/etc/master.passwd' # FreeBSD passwd
+# Note: while the above has the correct location for where
+# encrypted passwords are stored on FreeBSD, the code below doesn't
+# invoke adduser in lieu of useradd, nor pw in lieu of usermod.
+# That is, this won't work on FreeBSD.
+
 def get_bin_path(module, arg):
     if os.path.exists('/usr/sbin/%s' % arg):
         return '/usr/sbin/%s' % arg
@@ -198,16 +207,28 @@ def get_pwd_info(user):
 def user_info(user):
     if not user_exists(user):
         return False
-    try:
     info = get_pwd_info(user)
-        if HAVE_SPWD:
-            sinfo = spwd.getspnam(user)
-    except KeyError:
-        return False
-    if HAVE_SPWD:
-        info[1] = sinfo[1]
+    if len(info[1]) == 1 or len(info[1]) == 0:
+        info[1] = user_password(user)
     return info
 
+def user_password(user):
+    passwd = ''
+    if not user_exists(user):
+        return passwd
+    if HAVE_SPWD:
+        try:
+            passwd = spwd.getspnam(user)[1]
+        except KeyError:
+            return passwd
+    else:
+        # Read shadow file for user's encrypted password string
+        if os.path.exists(SHADOWFILE) and os.access(SHADOWFILE, os.R_OK):
+            for line in open(SHADOWFILE).readlines():
+                if line.startswith('%s:' % user):
+                    passwd = line.split(':')[1]
+    return passwd
+
 # ===========================================
 
 def main():