Fix FTP/550 (ENODEV) for clients using "LIST -a"

The test for additional switches to the LIST command
must be performed before the path is joined. Otherwise,
the path will never be empty and the test will be skipped.
Fixes ENODEV error (FTP/550) on clients using "LIST -a".

source/ftpSession.cpp

@@ -1438,15 +1438,27 @@ void FtpSession::xferDir (char const *const args_, XferDirMode const mode_, bool
 		                            (args_[2] == '\0' || args_[2] == ' ');
 
 		// an argument was provided
-		auto const path = buildResolvedPath (m_cwd, args_);
-		if (path.empty ())
+
+		// work around broken clients that think LIST -a/-l is valid
+		if (workaround_)
 		{
-			if (needWorkaround)
+			if (args_[0] == '-' && (args_[1] == 'a' || args_[1] == 'l'))
 			{
-				xferDir (args_ + 2 + (args_[2] == ' '), mode_, false);
-				return;
+				char const *args = &args_[2];
+				if (*args == '\0' || *args == ' ')
+				{
+					if (*args == ' ')
+						++args;
+
+					xferDir (args, mode_, false);
+					return;
+				}
 			}
+		}
 
+		auto const path = buildResolvedPath (m_cwd, args_);
+		if (path.empty ())
+		{
 			sendResponse ("550 %s\r\n", std::strerror (errno));
 			setState (State::COMMAND, true, true);
 			return;
@@ -1455,12 +1467,6 @@ void FtpSession::xferDir (char const *const args_, XferDirMode const mode_, bool
 		stat_t st;
 		if (tzStat (path.c_str (), &st) != 0)
 		{
-			if (needWorkaround)
-			{
-				xferDir (args_ + 2 + (args_[2] == ' '), mode_, false);
-				return;
-			}
-
 			sendResponse ("550 %s\r\n", std::strerror (errno));
 			setState (State::COMMAND, true, true);
 			return;