Make error reporting more 'local' for various configurations of nss_ldap packages

https://fedorahosted.org/freeipa/ticket/1369

When nss_ldap-based configuration does not work, report proper package name instead of always assuming nss_ldap.
At least, in RHEL6 and Fedora appropriate package is called nss-pam-ldapd while in older releases and other
distributions it might be called differently.

The change makes less confusing error reporting. It also introduces common utility function package_installed_name()
which provides an interface to query package manager for existence of mutually exclusive packages which is
helpful to distinguish between different configuration paths.

1 files changed, 18 insertions, 0 deletions

diff --git a/ipapython/ipautil.py b/ipapython/ipautil.py
index da6e94c85..6bfebcaeb 100644
--- a/ipapython/ipautil.py
+++ b/ipapython/ipautil.py
@@ -1171,3 +1171,21 @@ def bind_port_responder(port, socket_stream=True, socket_timeout=None, responder
                 s.sendto(responder_data, addr)
     finally:
         s.close()
+
+def package_installed_name(packages):
+    """
+    Find out which of mutually exclusive packages is installed
+    
+    packages is a list of package names to check
+    
+    Returns package name or None
+    """
+
+    args = ["/bin/rpm","-q","--queryformat","%{NAME}"]
+    for package in packages:
+        try:
+            (package_name, error, retcode) = run(args+[package])
+            return package_name
+        except CalledProcessError:
+            continue
+    return None