tables: Add default values for POSIX os_version (#3848)

osquery/tables/system/linux/os_version.cpp

@@ -41,14 +41,13 @@ const std::map<std::string, std::string> kOSReleaseColumns = {
     {"VERSION_ID", "_id"},
 };
 
-QueryData genOSRelease() {
+QueryData genOSRelease(Row& r) {
   // This will parse /etc/os-version according to the systemd manual.
   std::string content;
   if (!readFile(kOSRelease, content).ok()) {
-    return {};
+    return {r};
   }
 
-  Row r;
   for (const auto& line : osquery::split(content, "\n")) {
     auto fields = osquery::split(line, "=", 1);
     if (fields.size() != 2) {
@@ -87,22 +86,32 @@ QueryData genOSRelease() {
 }
 
 QueryData genOSVersion(QueryContext& context) {
+  Row r;
+
+  // Set defaults if we cannot determine the version.
+  r["name"] = "Unknown";
+  r["major"] = "0";
+  r["minor"] = "0";
+  r["patch"] = "0";
+  r["platform"] = "posix";
+
   if (isReadable(kOSRelease)) {
     boost::system::error_code ec;
     // Funtoo has an empty os-release file.
     if (boost::filesystem::file_size(kOSRelease, ec) > 0) {
-      return genOSRelease();
+      return genOSRelease(r);
     }
   }
 
-  Row r;
   std::string content;
   if (readFile(kRedhatRelease, content).ok()) {
+    r["platform"] = "rhel";
     r["platform_like"] = "rhel";
   } else if (readFile(kGentooRelease, content).ok()) {
+    r["platform"] = "gentoo";
     r["platform_like"] = "gentoo";
   } else {
-    return {};
+    return {r};
   }
 
   boost::algorithm::trim_all(content);