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, 42 insertions, 3 deletions

diff --git a/src/zen/cmds/up_cmd.cpp b/src/zen/cmds/up_cmd.cpp
index 61a901fd6..3095211b6 100644
--- a/src/zen/cmds/up_cmd.cpp
+++ b/src/zen/cmds/up_cmd.cpp
@@ -2,7 +2,9 @@
 
 #include "up_cmd.h"
 
+#include <zencore/compactbinary.h>
 #include <zencore/filesystem.h>
+#include <zencore/fmtutils.h>
 #include <zencore/logging.h>
 #include <zencore/process.h>
 #include <zencore/timer.h>
@@ -48,10 +50,9 @@ UpCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 			};
 			std::vector<EntryInfo> RunningEntries;
 			State.Snapshot([&RunningEntries, DesiredPort = this->m_Port](const zen::ZenServerState::ZenServerEntry& Entry) {
-				uint32_t Pid = Entry.Pid.load();
-				if (IsProcessRunning(Pid) && (DesiredPort == 0 || Entry.DesiredListenPort.load() == DesiredPort))
+				if (DesiredPort == 0 || Entry.DesiredListenPort.load() == DesiredPort)
 				{
-					RunningEntries.push_back(EntryInfo{.Pid			  = Pid,
+					RunningEntries.push_back(EntryInfo{.Pid			  = Entry.Pid.load(),
 													   .DesiredPort	  = Entry.DesiredListenPort.load(),
 													   .EffectivePort = Entry.EffectiveListenPort.load()});
 				}
@@ -86,6 +87,7 @@ UpCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 	if (!Server.WaitUntilReady(Timeout))
 	{
 		ZEN_ERROR("zen server launch failed (timed out)");
+		return 1;
 	}
 	else
 	{
@@ -101,6 +103,7 @@ AttachCommand::AttachCommand()
 {
 	m_Options.add_option("", "p", "port", "Host port", cxxopts::value(m_Port)->default_value("8558"), "<hostport>");
 	m_Options.add_option("lifetime", "", "owner-pid", "Specify owning process id", cxxopts::value(m_OwnerPid), "<identifier>");
+	m_Options.add_option("", "", "data-dir", "Path to data directory to inspect for running server", cxxopts::value(m_DataDir), "<file>");
 }
 
 AttachCommand::~AttachCommand() = default;
@@ -119,6 +122,24 @@ AttachCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 	Instance.Initialize();
 	Instance.Sweep();
 	ZenServerState::ZenServerEntry* Entry = Instance.Lookup(m_Port);
+
+	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;
+		}
+		Entry = Instance.LookupByEffectivePort(Info.EffectiveListenPort);
+	}
+
 	if (!Entry)
 	{
 		ZEN_WARN("no zen server instance to add sponsor process to");
@@ -142,6 +163,7 @@ DownCommand::DownCommand()
 	m_Options.add_option("", "p", "port", "Host port", cxxopts::value(m_Port)->default_value("0"), "<hostport>");
 	m_Options.add_option("", "f", "force", "Force terminate if graceful shutdown fails", cxxopts::value(m_ForceTerminate), "<force>");
 	m_Options.add_option("", "b", "base-dir", "Parent folder of server executable", cxxopts::value(m_ProgramBaseDir), "<directory>");
+	m_Options.add_option("", "", "data-dir", "Path to data directory to inspect for running server", cxxopts::value(m_DataDir), "<file>");
 }
 
 DownCommand::~DownCommand() = default;
@@ -167,6 +189,23 @@ DownCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 		m_ProgramBaseDir			  = ExePath.parent_path();
 	}
 
+	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;
+		}
+		Entry = Instance.LookupByEffectivePort(Info.EffectiveListenPort);
+	}
+
 	if (Entry)
 	{
 		int			   EntryPort		= (int)Entry->DesiredListenPort.load();