Create POSIX static class for missing functionality in .NET lib

Program.cs

@@ -20,13 +20,21 @@ using Process = System.Diagnostics.Process;
 using Config;
 
 namespace i3csstatus {
-	static class ProcesExtended
+	static class POSIX
 	{
 		[DllImport("libc", SetLastError = true)]
+		public static extern int mkfifo(string path, int mode);
+		[DllImport("libc", CallingConvention=CallingConvention.Cdecl, SetLastError=true)]
 		public static extern int kill(int pid, int sig);
+		public static int SIGUSR1 = 10;
+		public static int EEXIST = 17;
+		public static int ERRNO { get => Marshal.GetLastPInvokeError();}
+	}
+	static class ProcesExtended
+	{
 		public static int KillBySignal(this Process p, int sig)
 		{
-			return kill(p.Id, sig);
+			return POSIX.kill(p.Id, sig);
 		}
 	}
 	static class JsonExtended
@@ -247,7 +255,7 @@ text = ERR
 				if(lastGet_ms + cache_ms > t)
 					return;
 				lastGet_ms = t;
-				process.KillBySignal(10);
+				process.KillBySignal(POSIX.SIGUSR1);
 				string line = process.StandardOutput.ReadLine();
 				if(line == null)
 				{