Rename SetSeverity to SetSeverityFromString and check for valid severity

src/anbox/daemon.cpp

@@ -43,8 +43,8 @@ Daemon::Daemon()
   Log().Init(anbox::Logger::Severity::kWarning);
 
   const auto log_level = utils::get_env_value("ANBOX_LOG_LEVEL", "");
-  if (!log_level.empty())
-    Log().SetSeverity(log_level);
+  if (!log_level.empty() || !Log().SetSeverityFromString(log_level))
+    WARNING("Failed to set logging severity to '%s'", log_level);
 }
 
 int Daemon::Run(const std::vector<std::string> &arguments) try {

src/anbox/logger.cpp

@@ -107,7 +107,7 @@ void SetInstance(const std::shared_ptr<anbox::Logger>& logger) {
 }
 namespace anbox {
 
-void Logger::SetSeverity(const std::string& severity) {
+bool Logger::SetSeverityFromString(const std::string& severity) {
   if (severity == "trace")
     SetSeverity(Severity::kTrace);
   else if (severity == "debug")
@@ -120,6 +120,9 @@ void Logger::SetSeverity(const std::string& severity) {
     SetSeverity(Severity::kError);
   else if (severity == "fatal")
     SetSeverity(Severity::kFatal);
+  else
+    return false;
+  return true;
 }
 
 void Logger::Trace(const std::string& message,

src/anbox/logger.h

@@ -49,7 +49,7 @@ class Logger : public DoNotCopyOrMove {
 
   virtual void Init(const Severity& severity = Severity::kWarning) = 0;
 
-  void SetSeverity(const std::string &severity);
+  bool SetSeverityFromString(const std::string &severity);
   virtual void SetSeverity(const Severity& severity) = 0;
 
   virtual void Log(Severity severity, const std::string& message,