improve mutex startup error (#96)

* separate collision of shared mutex from failure to create shared mutex

1 files changed, 7 insertions, 2 deletions

diff --git a/src/zenserver/zenserver.cpp b/src/zenserver/zenserver.cpp
index 9f24960bd..48ea89204 100644
--- a/src/zenserver/zenserver.cpp
+++ b/src/zenserver/zenserver.cpp
@@ -8,6 +8,7 @@
 #include <zencore/compactbinarybuilder.h>
 #include <zencore/compactbinaryvalidation.h>
 #include <zencore/config.h>
+#include <zencore/except.h>
 #include <zencore/filesystem.h>
 #include <zencore/fmtutils.h>
 #include <zencore/iobuffer.h>
@@ -148,9 +149,13 @@ ZenServer::Initialize(const ZenServerOptions& ServerOptions, ZenServerState::Zen
 
 	std::string MutexName = fmt::format("zen_{}", ServerOptions.BasePort);
 
-	if (NamedMutex::Exists(MutexName) || ((m_ServerMutex.Create(MutexName) == false)))
+	if (NamedMutex::Exists(MutexName))
 	{
-		throw std::runtime_error(fmt::format("Failed to create mutex '{}' - is another instance already running?", MutexName).c_str());
+		throw std::runtime_error(fmt::format("Mutex '{}' already exists - is another instance already running?", MutexName).c_str());
+	}
+	if (m_ServerMutex.Create(MutexName) == false)
+	{
+		ThrowLastError(fmt::format("Failed to create mutex '{}'", MutexName).c_str());
 	}
 
 	InitializeState(ServerOptions);