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, 73 insertions, 32 deletions

diff --git a/src/zencore/process.cpp b/src/zencore/process.cpp
index df2a87352..8fddc9562 100644
--- a/src/zencore/process.cpp
+++ b/src/zencore/process.cpp
@@ -813,6 +813,54 @@ GetProcessId(CreateProcResult ProcId)
 #endif
 }
 
+std::filesystem::path
+GetProcessExecutablePath(int Pid, std::error_code& OutEc)
+{
+#if ZEN_PLATFORM_WINDOWS
+	HANDLE ModuleSnapshotHandle = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, (DWORD)Pid);
+	if (ModuleSnapshotHandle != INVALID_HANDLE_VALUE)
+	{
+		auto		  __ = MakeGuard([&]() { CloseHandle(ModuleSnapshotHandle); });
+		MODULEENTRY32 ModuleEntry;
+		ModuleEntry.dwSize = sizeof(MODULEENTRY32);
+		if (Module32First(ModuleSnapshotHandle, (LPMODULEENTRY32)&ModuleEntry))
+		{
+			std::filesystem::path ProcessExecutablePath(ModuleEntry.szExePath);
+			return ProcessExecutablePath;
+		}
+		OutEc = MakeErrorCodeFromLastError();
+		return {};
+	}
+	OutEc = MakeErrorCodeFromLastError();
+	return {};
+#endif	// ZEN_PLATFORM_WINDOWS
+#if ZEN_PLATFORM_MAC
+	char Buffer[PROC_PIDPATHINFO_MAXSIZE];
+	int	 Res = proc_pidpath(Pid, Buffer, sizeof(Buffer));
+	if (Res > 0)
+	{
+		std::filesystem::path ProcessExecutablePath(Buffer);
+		return ProcessExecutablePath;
+	}
+	OutEc = MakeErrorCodeFromLastError();
+	return {};
+#endif	// ZEN_PLATFORM_MAC
+#if ZEN_PLATFORM_LINUX
+	std::filesystem::path EntryPath	  = std::filesystem::path("/proc") / fmt::format("{}", Pid);
+	std::filesystem::path ExeLinkPath = EntryPath / "exe";
+	char				  Link[4096];
+	ssize_t				  BytesRead = readlink(ExeLinkPath.c_str(), Link, sizeof(Link) - 1);
+	if (BytesRead > 0)
+	{
+		Link[BytesRead] = '\0';
+		std::filesystem::path ProcessExecutablePath(Link);
+		return ProcessExecutablePath;
+	}
+	OutEc = MakeErrorCodeFromLastError();
+	return {};
+#endif	// ZEN_PLATFORM_LINUX
+}
+
 std::error_code
 FindProcess(const std::filesystem::path& ExecutableImage, ProcessHandle& OutHandle)
 {
@@ -832,23 +880,22 @@ FindProcess(const std::filesystem::path& ExecutableImage, ProcessHandle& OutHand
 		{
 			if (ExecutableImage.filename() == Entry.szExeFile)
 			{
-				HANDLE ModuleSnapshotHandle = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, Entry.th32ProcessID);
-				if (ModuleSnapshotHandle != INVALID_HANDLE_VALUE)
+				std::error_code		  Ec;
+				std::filesystem::path EntryPath = GetProcessExecutablePath(Entry.th32ProcessID, Ec);
+				if (!Ec)
 				{
-					auto		  __ = MakeGuard([&]() { CloseHandle(ModuleSnapshotHandle); });
-					MODULEENTRY32 ModuleEntry;
-					ModuleEntry.dwSize = sizeof(MODULEENTRY32);
-					if (Module32First(ModuleSnapshotHandle, (LPMODULEENTRY32)&ModuleEntry))
+					if (EntryPath == ExecutableImage)
 					{
-						std::filesystem::path EntryPath(ModuleEntry.szExePath);
-						if (EntryPath == ExecutableImage)
+						HANDLE Handle =
+							OpenProcess(PROCESS_TERMINATE | SYNCHRONIZE | PROCESS_QUERY_INFORMATION, FALSE, Entry.th32ProcessID);
+						if (Handle == NULL)
+						{
+							return MakeErrorCodeFromLastError();
+						}
+						DWORD ExitCode = 0;
+						GetExitCodeProcess(Handle, &ExitCode);
+						if (ExitCode == STILL_ACTIVE)
 						{
-							HANDLE Handle =
-								OpenProcess(PROCESS_TERMINATE | SYNCHRONIZE | PROCESS_QUERY_INFORMATION, FALSE, Entry.th32ProcessID);
-							if (Handle == NULL)
-							{
-								return MakeErrorCodeFromLastError();
-							}
 							OutHandle.Initialize((void*)Handle);
 							return {};
 						}
@@ -876,16 +923,15 @@ FindProcess(const std::filesystem::path& ExecutableImage, ProcessHandle& OutHand
 			char Buffer[PROC_PIDPATHINFO_MAXSIZE];
 			for (uint32_t ProcIndex = 0; ProcIndex < ProcCount; ProcIndex++)
 			{
-				if (Processes[ProcIndex].kp_proc.p_stat != SZOMB)
+				pid_t				  Pid = Processes[ProcIndex].kp_proc.p_pid;
+				std::error_code		  Ec;
+				std::filesystem::path EntryPath = GetProcessExecutablePath(Pid, Ec);
+				if (!Ec)
 				{
-					pid_t Pid = Processes[ProcIndex].kp_proc.p_pid;
-					int	  Res = proc_pidpath(Pid, Buffer, sizeof(Buffer));
-					if (Res > 0)
+					if (EntryPath == ExecutableImage)
 					{
-						std::filesystem::path EntryPath(Buffer);
-						if (EntryPath == ExecutableImage)
+						if (Processes[ProcIndex].kp_proc.p_stat != SZOMB)
 						{
-							std::error_code Ec;
 							OutHandle.Initialize(Pid, Ec);
 							return Ec;
 						}
@@ -912,20 +958,15 @@ FindProcess(const std::filesystem::path& ExecutableImage, ProcessHandle& OutHand
 
 	for (uint32_t Pid : RunningPids)
 	{
-		char Status = GetPidStatus(Pid);
-		if (Status && (Status != 'Z'))
+		std::error_code		  Ec;
+		std::filesystem::path EntryPath = GetProcessExecutablePath((int)Pid, Ec);
+		if (!Ec)
 		{
-			std::filesystem::path EntryPath	  = std::filesystem::path("/proc") / fmt::format("{}", Pid);
-			std::filesystem::path ExeLinkPath = EntryPath / "exe";
-			char				  Link[4096];
-			ssize_t				  BytesRead = readlink(ExeLinkPath.c_str(), Link, sizeof(Link) - 1);
-			if (BytesRead > 0)
+			if (EntryPath == ExecutableImage)
 			{
-				Link[BytesRead] = '\0';
-				std::filesystem::path ExePath(Link);
-				if (ExePath == ExecutableImage)
+				char Status = GetPidStatus(Pid);
+				if (Status && (Status != 'Z'))
 				{
-					std::error_code Ec;
 					OutHandle.Initialize(Pid, Ec);
 					return Ec;
 				}