Make -Wl,-z,now work on older systems

CMakeLists.txt

@@ -5,6 +5,9 @@
 # https://github.com/desktop-app/legal/blob/master/LEGAL
 
 add_subdirectory(external)
+if (LINUX AND NOT DESKTOP_APP_USE_PACKAGED)
+    add_subdirectory(linux_xcb_helper)
+endif()
 if (LINUX
     AND NOT DESKTOP_APP_USE_PACKAGED
     AND NOT DESKTOP_APP_DISABLE_WAYLAND_INTEGRATION)

external/qt/CMakeLists.txt

@@ -290,6 +290,8 @@ else()
         endif()
         target_link_libraries(external_qt
         INTERFACE
+            desktop-app::linux_xcb_helper
+            $<TARGET_FILE:desktop-app::linux_xcb_helper>
             desktop-app::linux_gtk_helper
             $<TARGET_FILE:desktop-app::linux_gtk_helper>
             desktop-app::linux_glib_helper

external/qt/qt6/CMakeLists.txt

@@ -264,6 +264,8 @@ else()
         endif()
         target_link_libraries(external_qt
         INTERFACE
+            desktop-app::linux_xcb_helper
+            $<TARGET_FILE:desktop-app::linux_xcb_helper>
             desktop-app::linux_gtk_helper
             $<TARGET_FILE:desktop-app::linux_gtk_helper>
             desktop-app::linux_glib_helper

linux_xcb_helper/CMakeLists.txt

@@ -0,0 +1,19 @@
+# This file is part of Desktop App Toolkit,
+# a set of libraries for developing nice desktop applications.
+#
+# For license and copyright information please follow this link:
+# https://github.com/desktop-app/legal/blob/master/LEGAL
+
+add_library(linux_xcb_helper STATIC)
+init_target(linux_xcb_helper "(external)")
+add_library(desktop-app::linux_xcb_helper ALIAS linux_xcb_helper)
+
+nice_target_sources(linux_xcb_helper ${CMAKE_CURRENT_SOURCE_DIR}
+PRIVATE
+    linux_xcb_helper.cpp
+)
+
+target_link_libraries(linux_xcb_helper
+PUBLIC
+    ${CMAKE_DL_LIBS}
+)

linux_xcb_helper/linux_xcb_helper.cpp

@@ -0,0 +1,53 @@
+// This file is part of Desktop App Toolkit,
+// a set of libraries for developing nice desktop applications.
+//
+// For license and copyright information please follow this link:
+// https://github.com/desktop-app/legal/blob/master/LEGAL
+//
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <xcb/xcb.h>
+#include <xcb/xcbext.h>
+
+unsigned int xcb_send_request_with_fds(
+		xcb_connection_t *c,
+		int flags,
+		struct iovec *vector,
+		const xcb_protocol_request_t *req,
+		unsigned int num_fds,
+		int *fds) {
+	const auto send_request_with_fds = reinterpret_cast<unsigned int(*)(
+		xcb_connection_t*,
+		int,
+		struct iovec*,
+		const xcb_protocol_request_t*,
+		unsigned int,
+		int*)>(dlsym(RTLD_NEXT, "xcb_send_request_with_fds"));
+
+	if (!dlerror()) {
+		return send_request_with_fds(c, flags, vector, req, num_fds, fds);
+	}
+
+	const auto send_fd = reinterpret_cast<void(*)(xcb_connection_t*, int)>(
+		dlsym(RTLD_NEXT, "xcb_send_fd"));
+
+	if (dlerror()) {
+		abort();
+	}
+
+	const auto send_request = reinterpret_cast<unsigned int(*)(
+		xcb_connection_t*,
+		int,
+		struct iovec*,
+		const xcb_protocol_request_t*)>(dlsym(RTLD_NEXT, "xcb_send_request"));
+
+	if (dlerror()) {
+		abort();
+	}
+
+	for (int i = 0; i != num_fds; ++i) {
+		send_fd(c, fds[i]);
+	}
+
+	return send_request(c, flags, vector, req);
+}

options_linux.cmake

@@ -112,6 +112,7 @@ if (NOT DESKTOP_APP_USE_PACKAGED)
         -rdynamic
         -fwhole-program
         -Wl,-z,relro
+        -Wl,-z,now
         -pie
     )
 endif()