refactor zen command return value handling (#487)

- Improvement: Use consistent language for command line argument parsing errors
- Improvement: Changed zen command parsing errors to output help first and error last to make it easier to spot the error
- Improvement: Refactor zen command return codes to conform to valid Linux range (0-255)

        kSuccess     = 0,
        kOtherError  = 1,
        kBadInput    = 2,

        kOutOfMemory = 16,
        kOutOfDisk   = 17,

        kAssertError = 70,
        
        kHttpOtherClientError = 80,
        kHttpCantConnectError = 81,
        kHttpNotFound         = 66,  // NotFound(404)
        kHttpUnauthorized     = 77,  // Unauthorized(401),
        kHttpSLLError         = 82,
        kHttpForbidden        = 83,  // Forbidden(403)
        kHttpTimeout          = 84,  // RequestTimeout(408)
        kHttpConflict         = 85,  // Conflict(409)
        kHttpNoHost           = 86,
        
        kHttpOtherServerError	   = 90,
        kHttpInternalServerError = 91,  // InternalServerError(500)
        kHttpServiceUnavailable  = 69,  // ServiceUnavailable(503)
        kHttpBadGateway          = 92,  // BadGateway(502)
        kHttpGatewayTimeout      = 93,  // GatewayTimeout(504)

1 files changed, 14 insertions, 18 deletions

diff --git a/src/zen/cmds/trace_cmd.cpp b/src/zen/cmds/trace_cmd.cpp
index 85caf33b8..41a30068c 100644
--- a/src/zen/cmds/trace_cmd.cpp
+++ b/src/zen/cmds/trace_cmd.cpp
@@ -20,21 +20,21 @@ TraceCommand::TraceCommand()
 
 TraceCommand::~TraceCommand() = default;
 
-int
+void
 TraceCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 {
 	ZEN_UNUSED(GlobalOptions);
 
 	if (!ParseOptions(argc, argv))
 	{
-		return 0;
+		return;
 	}
 
 	m_HostName = ResolveTargetHostSpec(m_HostName);
 
 	if (m_HostName.empty())
 	{
-		throw OptionParseException("unable to resolve server specification");
+		throw OptionParseException("Unable to resolve server specification", m_Options.help());
 	}
 
 	zen::HttpClient Http(m_HostName);
@@ -44,13 +44,12 @@ TraceCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 		if (zen::HttpClient::Response Response = Http.Post("/admin/trace/stop"sv))
 		{
 			ZEN_CONSOLE("OK: {}", Response.ToText());
-			return 0;
 		}
 		else
 		{
-			ZEN_CONSOLE_ERROR("trace stop failed: {}", Response.ToText());
-			return 1;
+			Response.ThrowError("Trace stop failed");
 		}
+		return;
 	}
 
 	std::string StartArg;
@@ -68,26 +67,23 @@ TraceCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 		if (zen::HttpClient::Response Response = Http.Post(fmt::format("/admin/trace/start?{}"sv, StartArg)))
 		{
 			ZEN_CONSOLE("OK: {}", Response.ToText());
-			return 0;
 		}
 		else
 		{
-			ZEN_CONSOLE_ERROR("trace start failed: {}", Response.ToText());
-			return 1;
+			Response.ThrowError("Trace start failed");
 		}
 	}
-
-	if (zen::HttpClient::Response Response = Http.Get("/admin/trace"sv))
-	{
-		ZEN_CONSOLE("OK: {}", Response.ToText());
-		return 0;
-	}
 	else
 	{
-		ZEN_CONSOLE_ERROR("trace status failed: {}", Response.ToText());
+		if (zen::HttpClient::Response Response = Http.Get("/admin/trace"sv))
+		{
+			ZEN_CONSOLE("OK: {}", Response.ToText());
+		}
+		else
+		{
+			Response.ThrowError("Trace status failed");
+		}
 	}
-
-	return 1;
 }
 
 }  // namespace zen