commit 0961fae6f97fc7f201daa9aee9db1de01440d319
author Matthew Barth <msbarth@us.ibm.com> Fri Nov 15 09:00:27 2019 -0600
committer Matthew Barth <msbarth@us.ibm.com> Tue Jan 07 14:22:11 2020 -0600
tree 9514d59898c4882c72195ab5dc74b4f56cc80f4f
parent fd05d649b374850a2ef8523e9f310c402e8d46e1

presence: Parse JSON input file

Load, parse, and store the JSON configuration data to be used in
populating the fan presence policies.

Tested:
    Valid json file is parsed without error
    Invalid json file throws exception

Change-Id: Ib5e28533177ece31620877a6e146ce61025b4fb3
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>

presence/json_config.cpp

diff --git a/presence/json_config.cpp b/presence/json_config.cpp
index 5bb7c3c..4a9d493 100644
--- a/presence/json_config.cpp
+++ b/presence/json_config.cpp
@@ -14,6 +14,10 @@
  * limitations under the License.
  */
 #include <string>
+#include <filesystem>
+#include <fstream>
+#include <nlohmann/json.hpp>
+#include <phosphor-logging/log.hpp>
 
 #include "json_config.hpp"
 
@@ -24,11 +28,39 @@
 namespace presence
 {
 
+using json = nlohmann::json;
+namespace fs = std::filesystem;
+using namespace phosphor::logging;
+
 policies JsonConfig::_policies;
 
 JsonConfig::JsonConfig(const std::string& jsonFile)
 {
+    fs::path confFile{jsonFile};
+    std::ifstream file;
+    json jsonConf;
 
+    if (fs::exists(confFile))
+    {
+        file.open(confFile);
+        try
+        {
+            jsonConf = json::parse(file);
+        }
+        catch (std::exception& e)
+        {
+            log<level::ERR>("Failed to parse JSON config file",
+                            entry("JSON_FILE=%s", jsonFile.c_str()),
+                            entry("JSON_ERROR=%s", e.what()));
+            throw std::runtime_error("Failed to parse JSON config file");
+        }
+    }
+    else
+    {
+        log<level::ERR>("Unable to open JSON config file",
+                        entry("JSON_FILE=%s", jsonFile.c_str()));
+        throw std::runtime_error("Unable to open JSON config file");
+    }
 }
 
 const policies& JsonConfig::get()