fix(flutter): initialize SIGPIPE in the Rust native entry

Share SIGPIPE initialization between the Linux and macOS native runners before core startup. Remove the Linux C++ initialization.

flutter/linux/main.cc

@@ -1,6 +1,5 @@
 #include <dlfcn.h>
 #include <limits.h>
-#include <signal.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
@@ -67,12 +66,6 @@ bool flutter_rustdesk_core_main() {
 }
 
 int main(int argc, char** argv) {
-  // This C++ entry point bypasses Rust's SIGPIPE initialization. A closed IPC
-  // peer must produce EPIPE, not terminate the server before Rust handles it.
-  if (signal(SIGPIPE, SIG_IGN) == SIG_ERR) {
-    perror("Failed to ignore SIGPIPE");
-    return 1;
-  }
   if (!flutter_rustdesk_core_main()) {
       return 0;
   }

src/flutter.rs

@@ -105,6 +105,16 @@ fn load_plugin_in_app_path(dll_name: &str) -> Result<Library, LibError> {
 #[cfg(not(windows))]
 #[no_mangle]
 pub extern "C" fn rustdesk_core_main() -> bool {
+    #[cfg(any(target_os = "linux", target_os = "macos"))]
+    {
+        use hbb_common::libc;
+
+        // Native runners bypass Rust's startup, which normally ignores SIGPIPE.
+        if unsafe { libc::signal(libc::SIGPIPE, libc::SIG_IGN) } == libc::SIG_ERR {
+            eprintln!("Failed to ignore SIGPIPE: {}", std::io::Error::last_os_error());
+            std::process::exit(1);
+        }
+    }
     #[cfg(not(any(target_os = "android", target_os = "ios")))]
     if crate::core_main::core_main().is_some() {
         return true;