Fixes for the XDG Base Dirs implementation (#330) (#419)

Fix XDG Base Dirs implementation

src/login.c

@@ -303,21 +303,41 @@ void remove_utmp_entry(struct utmp *entry) {
 
 void xauth(const char* display_name, const char* shell, char* pwd)
 {
-	const char* xauth_file = ".lyxauth";
+	const char* xauth_file = "lyxauth";
 	char* xauth_dir = getenv("XDG_RUNTIME_DIR");
 	if ((xauth_dir == NULL) || (*xauth_dir == '\0'))
 	{
-		xauth_dir = getenv("XDG_CONFIG_DIR");
+		xauth_dir = getenv("XDG_CONFIG_HOME");
+		struct stat sb;
 		if ((xauth_dir == NULL) || (*xauth_dir == '\0'))
+		{
+			xauth_dir = strdup(pwd);
+			strcat(xauth_dir, "/.config");
+			stat(xauth_dir, &sb);
+			if (S_ISDIR(sb.st_mode))
+			{
+				strcat(xauth_dir, "/ly");
+			}
+			else
+			{
+				xauth_dir = pwd;
+				xauth_file = ".lyxauth";
+			}
+		}
+		else
+		{
+			strcat(xauth_dir, "/ly");
+		}
+
+		// If .config/ly/ or XDG_CONFIG_HOME/ly/ doesn't exist and can't create the directory, use pwd
+		// Passing pwd beforehand is safe since stat will always evaluate false
+		stat(xauth_dir, &sb);
+		if (!S_ISDIR(sb.st_mode) && mkdir(xauth_dir, 0777) == -1)
 		{
 			xauth_dir = pwd;
-			xauth_file = "lyxauth";
+			xauth_file = ".lyxauth";
 		}
 	}
-	else
-	{
-		xauth_file = "lyxauth";
-	}
 
 	// trim trailing slashes
 	int i = strlen(xauth_dir) - 1;