Add API to retrieve settings

Add API to retrieve all settings objects of interest to the time
manager.

Change-Id: I3d121c08d0156cf481a3468e6c7ca9b71f53d666
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>

5 files changed, 162 insertions, 2 deletions

diff --git a/Makefile.am b/Makefile.am
index 090ee2c..b25fa12 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -6,6 +6,12 @@ sbin_PROGRAMS = \
 timemanager_SOURCES = \
 	time-register.c \
 	time-config.cpp \
-	time-manager.cpp
+	time-manager.cpp \
+	settings.cpp
 
-timemanager_LDFLAGS = $(SYSTEMD_LIBS) $(libmapper_LIBS)
+timemanager_LDFLAGS = \
+	$(SYSTEMD_LIBS) \
+	$(libmapper_LIBS) \
+	$(PHOSPHOR_DBUS_INTERFACES_LIBS) \
+	$(SDBUSPLUS_LIBS) \
+	$(PHOSPHOR_LOGGING_LIBS)
diff --git a/configure.ac b/configure.ac
index 2769644..fc0da82 100644
--- a/configure.ac
+++ b/configure.ac
@@ -16,6 +16,12 @@ AC_PROG_MAKE_SET
 # Checks for libraries.
 AC_CHECK_LIB([mapper], [mapper_get_service], ,[AC_MSG_ERROR([Could not find libmapper...openbmc/phosphor-objmgr package required])])
 PKG_CHECK_MODULES([SYSTEMD], [libsystemd >= 221])
+PKG_CHECK_MODULES([PHOSPHOR_DBUS_INTERFACES], [phosphor-dbus-interfaces],,\
+    AC_MSG_ERROR(["Requires phosphor-dbus-interfaces package."]))
+PKG_CHECK_MODULES([SDBUSPLUS], [sdbusplus],,
+    AC_MSG_ERROR(["Requires sdbusplus package."]))
+PKG_CHECK_MODULES([PHOSPHOR_LOGGING], [phosphor-logging],,\
+    AC_MSG_ERROR(["Requires phosphor-logging package."]))
 
 # Checks for header files.
 AC_CHECK_HEADER(systemd/sd-bus.h, ,[AC_MSG_ERROR([Could not find systemd/sd-bus.h...systemd developement package required])])
diff --git a/settings.cpp b/settings.cpp
new file mode 100644
index 0000000..650d03d
--- /dev/null
+++ b/settings.cpp
@@ -0,0 +1,92 @@
+#include <phosphor-logging/elog-errors.hpp>
+#include <phosphor-logging/log.hpp>
+#include "xyz/openbmc_project/Common/error.hpp"
+#include "settings.hpp"
+
+namespace settings
+{
+
+using namespace phosphor::logging;
+using namespace sdbusplus::xyz::openbmc_project::Common::Error;
+
+constexpr auto mapperService = "xyz.openbmc_project.ObjectMapper";
+constexpr auto mapperPath = "/xyz/openbmc_project/object_mapper";
+constexpr auto mapperIntf = "xyz.openbmc_project.ObjectMapper";
+
+Objects::Objects()
+{
+    auto bus = sdbusplus::bus::new_default();
+    std::vector<std::string> settingsIntfs =
+        {timeOwnerIntf, timeSyncIntf};
+    auto depth = 0;
+
+    auto mapperCall = bus.new_method_call(mapperService,
+                                          mapperPath,
+                                          mapperIntf,
+                                          "GetSubTree");
+    mapperCall.append(root);
+    mapperCall.append(depth);
+    mapperCall.append(settingsIntfs);
+    auto response = bus.call(mapperCall);
+    if (response.is_method_error())
+    {
+        log<level::ERR>("Error in mapper GetSubTree");
+        elog<InternalFailure>();
+    }
+
+    using Interfaces = std::vector<Interface>;
+    using MapperResponse = std::map<Path, std::map<Service, Interfaces>>;
+    MapperResponse result;
+    response.read(result);
+    if (result.empty())
+    {
+        log<level::ERR>("Invalid response from mapper");
+        elog<InternalFailure>();
+    }
+
+    for (const auto& iter : result)
+    {
+        const Path& path = iter.first;
+        const Interface& interface = iter.second.begin()->second.front();
+
+        if (timeOwnerIntf == interface)
+        {
+            timeOwner = path;
+        }
+        else if (timeSyncIntf == interface)
+        {
+            timeSyncMethod = path;
+        }
+    }
+}
+
+Service Objects::service(const Path& path, const Interface& interface) const
+{
+    auto bus = sdbusplus::bus::new_default();
+    using Interfaces = std::vector<Interface>;
+    auto mapperCall = bus.new_method_call(mapperService,
+                                          mapperPath,
+                                          mapperIntf,
+                                          "GetObject");
+    mapperCall.append(path);
+    mapperCall.append(Interfaces({interface}));
+
+    auto response = bus.call(mapperCall);
+    if (response.is_method_error())
+    {
+        log<level::ERR>("Error in mapper GetObject");
+        elog<InternalFailure>();
+    }
+
+    std::map<Service, Interfaces> result;
+    response.read(result);
+    if (result.empty())
+    {
+        log<level::ERR>("Invalid response from mapper");
+        elog<InternalFailure>();
+    }
+
+    return result.begin()->first;
+}
+
+} // namespace settings
diff --git a/settings.hpp b/settings.hpp
new file mode 100644
index 0000000..db1e5e4
--- /dev/null
+++ b/settings.hpp
@@ -0,0 +1,52 @@
+#pragma once
+
+#include <string>
+#include <sdbusplus/bus.hpp>
+
+namespace settings
+{
+
+using Path = std::string;
+using Service = std::string;
+using Interface = std::string;
+
+constexpr auto root = "/";
+constexpr auto timeOwnerIntf = "xyz.openbmc_project.Time.Owner";
+constexpr auto timeSyncIntf = "xyz.openbmc_project.Time.Synchronization";
+
+/** @class Objects
+ *  @brief Fetch paths of settings D-bus objects of interest upon construction
+ */
+struct Objects
+{
+    public:
+        /** @brief Constructor - fetch settings objects
+         *
+         * @param[in] bus - The D-bus bus object
+         */
+        Objects();
+        Objects(const Objects&) = default;
+        Objects& operator=(const Objects&) = default;
+        Objects(Objects&&) = default;
+        Objects& operator=(Objects&&) = default;
+        ~Objects() = default;
+
+        /** @brief Fetch D-bus service, given a path and an interface. The
+         *         service can't be cached because mapper returns unique
+         *         service names.
+         *
+         * @param[in] path - The D-bus object
+         * @param[in] interface - The D-bus interface
+         *
+         * @return std::string - the D-bus service
+         */
+        Service service(const Path& path, const Interface& interface) const;
+
+        /** @brief time owner settings object */
+        Path timeOwner;
+
+        /** @brief time sync method settings object */
+        Path timeSyncMethod;
+};
+
+} // namespace settings
diff --git a/time-config.hpp b/time-config.hpp
index 367380c..2d55b4b 100644
--- a/time-config.hpp
+++ b/time-config.hpp
@@ -1,5 +1,6 @@
 #include <map>
 #include <systemd/sd-bus.h>
+#include "settings.hpp"
 
 /** @class TimeConfig
  *  @brief Maintains various time modes and time owners.
@@ -224,6 +225,9 @@ private:
     // Needed to nudge Time Manager to reset offset
     bool        iv_SplitModeChanged;
 
+    /** @brief Settings objects of intereset */
+    settings::Objects settings;
+
     static constexpr auto cv_TimeModeFile = "/var/lib/obmc/saved_timeMode";
     static constexpr auto cv_TimeOwnerFile = "/var/lib/obmc/saved_timeOwner";
     static constexpr auto cv_DhcpNtpFile = "/var/lib/obmc/saved_dhcpNtp";