Add first user layer support.

Exposes user layer library which will be used by both
apphandler and netipmid for RAKP. Password is decrypted
from the special file which is used by pam-ipmi.

Change-Id: Ia6b99d4359a03843f19cd0e18f7269ad2e3cdb44
Signed-off-by: Richard Marian Thomaiyar <richard.marian.thomaiyar@linux.intel.com>
diff --git a/user_channel/shadowlock.hpp b/user_channel/shadowlock.hpp
new file mode 100644
index 0000000..8b09f21
--- /dev/null
+++ b/user_channel/shadowlock.hpp
@@ -0,0 +1,50 @@
+#pragma once
+
+#include <shadow.h>
+
+#include <phosphor-logging/elog-errors.hpp>
+#include <xyz/openbmc_project/Common/error.hpp>
+namespace phosphor
+{
+namespace user
+{
+namespace shadow
+{
+
+using InternalFailure =
+    sdbusplus::xyz::openbmc_project::Common::Error::InternalFailure;
+using namespace phosphor::logging;
+
+/** @class Lock
+ *  @brief Responsible for locking and unlocking /etc/shadow
+ */
+class Lock
+{
+  public:
+    Lock(const Lock&) = delete;
+    Lock& operator=(const Lock&) = delete;
+    Lock(Lock&&) = delete;
+    Lock& operator=(Lock&&) = delete;
+
+    /** @brief Default constructor that just locks the shadow file */
+    Lock()
+    {
+        if (!lckpwdf())
+        {
+            log<level::ERR>("Locking Shadow failed");
+            elog<InternalFailure>();
+        }
+    }
+    ~Lock()
+    {
+        if (!ulckpwdf())
+        {
+            log<level::ERR>("Un-Locking Shadow failed");
+            elog<InternalFailure>();
+        }
+    }
+};
+
+} // namespace shadow
+} // namespace user
+} // namespace phosphor