fix: linux, check load dylib in main.cc (#7901)

* fix: linux, check load dylib in main.cc

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

* Better error message

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

* refact error message

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

* Better error message

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

* check if "libnsl.so.1" is required, mainly for AppImage and yum

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

---------

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

flutter/lib/models/native_model.dart

@@ -108,24 +108,21 @@ class PlatformFFI {
       _ffiBind.sessionRegisterGpuTexture(
           sessionId: sessionId, display: display, ptr: ptr);
 
-  _loadDyLib() async {
+  /// Init the FFI class, loads the native Rust core library.
+  Future<void> init(String appType) async {
+    _appType = appType;
+    final dylib = isAndroid
+        ? DynamicLibrary.open('librustdesk.so')
+        : isLinux
+            ? DynamicLibrary.open('librustdesk.so')
+            : isWindows
+                ? DynamicLibrary.open('librustdesk.dll')
+                : isMacOS
+                    ? DynamicLibrary.open("liblibrustdesk.dylib")
+                    : DynamicLibrary.process();
+    debugPrint('initializing FFI $_appType');
     try {
-      final dylib = isAndroid
-          ? DynamicLibrary.open('librustdesk.so')
-          : isLinux
-              ? DynamicLibrary.open('librustdesk.so')
-              : isWindows
-                  ? DynamicLibrary.open('librustdesk.dll')
-                  : isMacOS
-                      ? DynamicLibrary.open("liblibrustdesk.dylib")
-                      : DynamicLibrary.process();
-      try {
-        _session_get_rgba =
-            dylib.lookupFunction<F3Dart, F3>("session_get_rgba");
-      } catch (e) {
-        print('Failed to lookup function "session_get_rgba": $e');
-        exit(1);
-      }
+      _session_get_rgba = dylib.lookupFunction<F3Dart, F3>("session_get_rgba");
       try {
         // SYSTEM user failed
         _dir = (await getApplicationDocumentsDirectory()).path;
@@ -133,19 +130,7 @@ class PlatformFFI {
         debugPrint('Failed to get documents directory: $e');
       }
       _ffiBind = RustdeskImpl(dylib);
-    } catch (e) {
-      print('Failed to load dynamic library: $e');
-      exit(1);
-    }
-  }
 
-  /// Init the FFI class, loads the native Rust core library.
-  Future<void> init(String appType) async {
-    _appType = appType;
-    await _loadDyLib();
-
-    debugPrint('initializing FFI $_appType');
-    try {
       if (isLinux) {
         // Start a dbus service, no need to await
         _ffiBind.mainStartDbusServer();

flutter/linux/main.cc

@@ -6,21 +6,31 @@
 typedef bool (*RustDeskCoreMain)();
 bool gIsConnectionManager = false;
 
+void print_help_install_pkg(const char* so);
+
 bool flutter_rustdesk_core_main() {
    void* librustdesk = dlopen(RUSTDESK_LIB_PATH, RTLD_LAZY);
    if (!librustdesk) {
-      fprintf(stderr,"load librustdesk.so failed\n");
+      fprintf(stderr,"Failed to load \"librustdesk.so\"\n");
       char* error;
       if ((error = dlerror()) != nullptr) {
-        fprintf(stderr, "%s", error);
+        fprintf(stderr, "%s\n", error);
+        // libnsl.so.1: cannot open shared object file: No such file or directory
+        char* libmissed = strstr(error, ": cannot open shared object file: No such file or directory");
+        if (libmissed != nullptr) {
+          *libmissed = '\0';
+          char* so = strdup(error);
+          print_help_install_pkg(so);
+          free(so);
+        }
       }
-     return true;
+     return false;
    }
    auto core_main = (RustDeskCoreMain) dlsym(librustdesk,"rustdesk_core_main");
    char* error;
    if ((error = dlerror()) != nullptr) {
-       fprintf(stderr, "error finding rustdesk_core_main: %s", error);
-       return true;
+       fprintf(stderr, "Program entry \"rustdesk_core_main\" is not found: %s\n", error);
+       return false;
    }
    return core_main();
 }
@@ -37,3 +47,80 @@ int main(int argc, char** argv) {
   g_autoptr(MyApplication) app = my_application_new();
   return g_application_run(G_APPLICATION(app), argc, argv);
 }
+
+typedef struct {
+  const char* mgr;
+  const char* search;
+} PkgMgrSearch;
+
+const PkgMgrSearch g_mgrs[] = {
+  {
+    "apt",
+    "apt-file search",
+  },
+  {
+    "dnf",
+    "dnf provides",
+  },
+  {
+    "yum",
+    "yum provides",
+  },
+  {
+    "zypper",
+    "zypper wp",
+  },
+  {
+    "pacman",
+    "pacman -Qo",
+  },
+  {
+    NULL,
+    NULL,
+  },
+};
+
+int is_command_exists(const char* command) {
+    char* path = getenv("PATH");
+    char* path_copy = strdup(path);
+    char* dir = strtok(path_copy, ":");
+
+    while (dir != NULL) {
+        char command_path[256];
+        snprintf(command_path, sizeof(command_path), "%s/%s", dir, command);
+        if (access(command_path, X_OK) == 0) {
+            free(path_copy);
+            return 1;
+        }
+        dir = strtok(NULL, ":");
+    }
+
+    free(path_copy);
+    return 0;
+}
+
+// We do not automatically search pkg 
+// as the search process can be time consuming and update may be required.
+void print_help_install_pkg(const char* so)
+{
+  if (strcmp(so, "libnsl.so.1") == 0) {
+    const char* mgr[] = {"yum", "dnf", NULL};
+    const char** m = mgr;
+    while (*m != NULL) {
+      if (is_command_exists(*m)) {
+        fprintf(stderr, "Please run \"%s install libnsl\" to install the required package.\n", *m);
+        return;
+      }
+      m++;
+    }
+  }
+
+  const PkgMgrSearch *mgr_search = g_mgrs;
+  while (mgr_search->mgr != NULL) {
+      if (is_command_exists(mgr_search->mgr) == 1) {
+        fprintf(stderr, "Please run \"%s %s\" to search and install the pkg.\n", mgr_search->search, so);
+        break;
+      }
+      mgr_search++;
+  }
+}