improved lock file handling (#50)

- Feature: `zen down`
  - --`data-dir` to specify a data directory to deduce which zen instance to bring down
- Feature: `zen attach`
  - --`data-dir` to specify a data directory to deduce which zen instance to attach to222
  
- Feature: `zen status`
  -  --`port` filter running zen instances based on port
  - --`data-dir` filter running zen instances based on information in the data directory

- Improvement: Trying to load a compact binary object from an empty file no longer causes access violation

1 files changed, 36 insertions, 4 deletions

diff --git a/src/zen/cmds/status_cmd.cpp b/src/zen/cmds/status_cmd.cpp
index cc936835a..16754e747 100644
--- a/src/zen/cmds/status_cmd.cpp
+++ b/src/zen/cmds/status_cmd.cpp
@@ -2,6 +2,7 @@
 
 #include "status_cmd.h"
 
+#include <zencore/compactbinary.h>
 #include <zencore/fmtutils.h>
 #include <zencore/logging.h>
 #include <zencore/string.h>
@@ -12,6 +13,8 @@ namespace zen {
 
 StatusCommand::StatusCommand()
 {
+	m_Options.add_option("", "p", "port", "Host port", cxxopts::value(m_Port)->default_value("0"), "<hostport>");
+	m_Options.add_option("", "", "data-dir", "Path to data directory to inspect for running server", cxxopts::value(m_DataDir), "<file>");
 }
 
 StatusCommand::~StatusCommand() = default;
@@ -19,7 +22,30 @@ StatusCommand::~StatusCommand() = default;
 int
 StatusCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 {
-	ZEN_UNUSED(GlobalOptions, argc, argv);
+	ZEN_UNUSED(GlobalOptions);
+
+	if (!ParseOptions(argc, argv))
+	{
+		return 0;
+	}
+
+	uint16_t EffectivePort = 0;
+	if (!m_DataDir.empty())
+	{
+		if (!std::filesystem::is_regular_file(m_DataDir / ".lock"))
+		{
+			ZEN_CONSOLE("lock file does not exist in directory '{}'", m_DataDir);
+			return 1;
+		}
+		LockFileInfo Info = ReadLockFilePayload(LoadCompactBinaryObject(IoBufferBuilder::MakeFromFile(m_DataDir / ".lock")));
+		std::string	 Reason;
+		if (!ValidateLockFileInfo(Info, Reason))
+		{
+			ZEN_CONSOLE("lock file in directory '{}' is not valid. Reason: '{}'", m_DataDir, Reason);
+			return 1;
+		}
+		EffectivePort = Info.EffectiveListenPort;
+	}
 
 	ZenServerState State;
 	if (!State.InitializeReadOnly())
@@ -31,9 +57,15 @@ StatusCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 
 	ZEN_CONSOLE("{:>5} {:>6} {:>24}", "port", "pid", "session");
 	State.Snapshot([&](const ZenServerState::ZenServerEntry& Entry) {
-		StringBuilder<25> SessionStringBuilder;
-		Entry.GetSessionId().ToString(SessionStringBuilder);
-		ZEN_CONSOLE("{:>5} {:>6} {:>24}", Entry.EffectiveListenPort.load(), Entry.Pid.load(), SessionStringBuilder);
+		bool MatchesAnyPort		  = (m_Port == 0) && (EffectivePort == 0);
+		bool MatchesEffectivePort = (EffectivePort != 0) && (Entry.EffectiveListenPort.load() == EffectivePort);
+		bool MatchesDesiredPort	  = (m_Port != 0) && (Entry.DesiredListenPort.load() == m_Port);
+		if (MatchesAnyPort || MatchesEffectivePort || MatchesDesiredPort)
+		{
+			StringBuilder<25> SessionStringBuilder;
+			Entry.GetSessionId().ToString(SessionStringBuilder);
+			ZEN_CONSOLE("{:>5} {:>6} {:>24}", Entry.EffectiveListenPort.load(), Entry.Pid.load(), SessionStringBuilder);
+		}
 	});
 
 	return 0;