refact, option, allow linux headless

Signed-off-by: fufesou <shuanglongchen@yeah.net>

src/platform/linux.rs

@@ -9,6 +9,9 @@ use hbb_common::{
     message_proto::Resolution,
     regex::{Captures, Regex},
 };
+#[cfg(all(feature = "linux_headless"))]
+#[cfg(not(any(feature = "flatpak", feature = "appimage")))]
+use hbb_common::config::CONFIG_OPTION_ALLOW_LINUX_HEADLESS;
 use std::{
     cell::RefCell,
     io::Write,
@@ -69,6 +72,13 @@ pub struct xcb_xfixes_get_cursor_image {
     pub pixels: *const c_long,
 }
 
+#[inline]
+#[cfg(feature = "linux_headless")]
+#[cfg(not(any(feature = "flatpak", feature = "appimage")))]
+pub fn is_headless_allowed() -> bool {
+    Config::get_option(CONFIG_OPTION_ALLOW_LINUX_HEADLESS) == "Y"
+}
+
 #[inline]
 fn sleep_millis(millis: u64) {
     std::thread::sleep(Duration::from_millis(millis));

src/platform/linux_desktop_manager.rs

@@ -109,6 +109,10 @@ pub fn try_start_desktop(_username: &str, _passsword: &str) -> String {
             // No need to verify password here.
             return "".to_owned();
         }
+        if username.is_empty() {
+            // Another user is logged in. No need to start a new xsession.
+            return "".to_owned();
+        }
 
         if let Some(msg) = detect_headless() {
             return msg.to_owned();