Create symbolic link after device tree is set

The commit creates API to set sym link to system config JSON
once device tree is set.

This is required because in existing code if VPD_SYMLIMK_PATH
is not found and fitconfig value is also not correctly set at
the same time, then symlink is created first and then code
flow goes to set fitconfig and reboot. It never goes into the
flow to set asset tag with factory reset flag set. Hence asset
tag never gets updated.

Test:
Clear sym link path,
set fitconfig to some default value
clear asset tag data from system inventory path

reboot the system.
Introspect the system inventory path.
Asset tag interface and data should be visible.

xyz.openbmc_project.Inventory.Decorator.AssetTag      interface -         -                                        -
.AssetTag                                             property  s         "Server-9043-MRX-13E8D2X"                emits-change writable

Signed-off-by: Sunny Srivastava <[email protected]>

Author: SunnySrivastava1984

vpd-manager/include/worker.hpp

@@ -486,6 +486,16 @@ class Worker
      */
     void primeSystemBlueprint();
 
+    /**
+     * @brief API to set symbolic link for system config JSON.
+     *
+     * Once correct device tree is set, symbolic link to the correct sytsem
+     * config JSON is set to be used in subsequent BMC boot.
+     *
+     * @param[in] i_systemJson - system config JSON.
+     */
+    void setJsonSymbolicLink(const std::string& i_systemJson);
+
     // Parsed JSON file.
     nlohmann::json m_parsedJson{};
 

vpd-manager/src/worker.cpp

@@ -423,34 +423,49 @@ static void setEnvAndReboot(const std::string& key, const std::string& value)
     bus.call_noreply(method);
 }
 
-void Worker::setDeviceTreeAndJson()
+void Worker::setJsonSymbolicLink(const std::string& i_systemJson)
 {
-    std::error_code ec;
-    ec.clear();
-    if (!std::filesystem::exists(VPD_SYMLIMK_PATH, ec))
+    std::error_code l_ec;
+    l_ec.clear();
+    if (!std::filesystem::exists(VPD_SYMLIMK_PATH, l_ec))
     {
-        if (ec)
+        if (l_ec)
         {
             throw std::runtime_error(
                 "File system call to exist failed with error = " +
-                ec.message());
+                l_ec.message());
         }
 
         // implies it is a fresh boot/factory reset.
         // Create the directory for hosting the symlink
-        if (!std::filesystem::create_directories(VPD_SYMLIMK_PATH, ec))
+        if (!std::filesystem::create_directories(VPD_SYMLIMK_PATH, l_ec))
         {
-            if (ec)
+            if (l_ec)
             {
                 throw std::runtime_error(
                     "File system call to create directory failed with error = " +
-                    ec.message());
+                    l_ec.message());
             }
         }
+    }
 
-        m_isFactoryResetDone = true;
+    // create a new symlink based on the system
+    std::filesystem::create_symlink(i_systemJson, INVENTORY_JSON_SYM_LINK,
+                                    l_ec);
+
+    if (l_ec)
+    {
+        throw std::runtime_error(
+            "create_symlink system call failed with error: " + l_ec.message());
     }
 
+    // If the flow is at this point implies the symlink was not present there.
+    // Considering this as factory reset.
+    m_isFactoryResetDone = true;
+}
+
+void Worker::setDeviceTreeAndJson()
+{
     // JSON is madatory for processing of this API.
     if (m_parsedJson.empty())
     {
@@ -460,14 +475,16 @@ void Worker::setDeviceTreeAndJson()
     types::VPDMapVariant parsedVpdMap;
     fillVPDMap(SYSTEM_VPD_FILE_PATH, parsedVpdMap);
 
-    // ToDo: Need to check is INVENTORY_JSON_SYM_LINK pointing to correct system
-    // JSON or not, if the sym link exists already.
+    // Implies it is default JSON.
+    std::string systemJson{JSON_ABSOLUTE_PATH_PREFIX};
+
+    // ToDo: Need to check if INVENTORY_JSON_SYM_LINK pointing to correct system
+    // This is required to support movement from rainier to Blue Ridge on the
+    // fly.
 
     // Do we have the entry for device tree in parsed JSON?
     if (m_parsedJson.find("devTree") == m_parsedJson.end())
     {
-        // Implies it is default JSON.
-        std::string systemJson{JSON_ABSOLUTE_PATH_PREFIX};
         getSystemJson(systemJson, parsedVpdMap);
 
         if (!systemJson.compare(JSON_ABSOLUTE_PATH_PREFIX))
@@ -476,51 +493,10 @@ void Worker::setDeviceTreeAndJson()
             throw DataException("Error in getting system JSON.");
         }
 
-        // create a new symlink based on the system
-        std::filesystem::create_symlink(systemJson, INVENTORY_JSON_SYM_LINK,
-                                        ec);
-        if (ec)
-        {
-            if (ec.value() == EEXIST)
-            {
-                ec.clear();
-                logging::logMessage(
-                    "Sym link already exists, file [" +
-                    std::string(INVENTORY_JSON_SYM_LINK) +
-                    "] deleting and creating sym link again, target file: " +
-                    systemJson);
-
-                if (std::filesystem::remove(INVENTORY_JSON_SYM_LINK, ec))
-                {
-                    std::filesystem::create_symlink(
-                        systemJson, INVENTORY_JSON_SYM_LINK, ec);
-                    if (ec)
-                    {
-                        throw std::runtime_error(
-                            "create_symlink system call failed when deleting existing link and recreating it again, error: " +
-                            ec.message());
-                    }
-                }
-                else
-                {
-                    logging::logMessage(
-                        "remove system call failed for file[" +
-                        std::string(INVENTORY_JSON_SYM_LINK) + "], error[" +
-                        ec.message() + "], continuing with existing sym link.");
-                }
-            }
-            else
-            {
-                throw std::runtime_error(
-                    "create_symlink system call failed with error: " +
-                    ec.message());
-            }
-        }
-
         // re-parse the JSON once appropriate JSON has been selected.
         try
         {
-            m_parsedJson = jsonUtility::getParsedJson(INVENTORY_JSON_SYM_LINK);
+            m_parsedJson = jsonUtility::getParsedJson(systemJson);
         }
         catch (const nlohmann::json::parse_error& ex)
         {
@@ -549,6 +525,12 @@ void Worker::setDeviceTreeAndJson()
     { // Skipping setting device tree as either devtree info is missing from
       // Json or it is rightly set.
 
+        // avoid setting symlink on every reboot.
+        if (!m_isSymlinkPresent)
+        {
+            setJsonSymbolicLink(systemJson);
+        }
+
         if (isSystemVPDOnDBus() &&
             jsonUtility::isBackupAndRestoreRequired(m_parsedJson))
         {