launch: use dup2 to reset daemon stdio over close+open

changelog/next.md

@@ -73,6 +73,7 @@ set shell id.
 - Fixed JsonAdapter sending unnecessary property changes for primitive values.
 - Fixed JsonAdapter serialization for lists.
 - Fixed pipewire crashes after hotplugging devices and changing default outputs.
+- Fixed launches failing for `--daemonize` on some systems.
 
 ## Packaging Changes
 

src/launch/main.cpp

@@ -84,21 +84,29 @@ void exitDaemon(int code) {
 
 	close(DAEMON_PIPE);
 
-	close(STDIN_FILENO);
-	close(STDOUT_FILENO);
-	close(STDERR_FILENO);
-
-	if (open("/dev/null", O_RDONLY) != STDIN_FILENO) { // NOLINT
-		qFatal() << "Failed to open /dev/null on stdin";
+	auto fd = open("/dev/null", O_RDWR);
+	if (fd == -1) {
+		qCritical().nospace() << "Failed to open /dev/null for daemon stdio" << errno << ": "
+		                      << qt_error_string();
+		return;
 	}
 
-	if (open("/dev/null", O_WRONLY) != STDOUT_FILENO) { // NOLINT
-		qFatal() << "Failed to open /dev/null on stdout";
+	if (dup2(fd, STDIN_FILENO) != STDIN_FILENO) { // NOLINT
+		qCritical().nospace() << "Failed to set daemon stdin to /dev/null" << errno << ": "
+		                      << qt_error_string();
 	}
 
-	if (open("/dev/null", O_WRONLY) != STDERR_FILENO) { // NOLINT
-		qFatal() << "Failed to open /dev/null on stderr";
+	if (dup2(fd, STDOUT_FILENO) != STDOUT_FILENO) { // NOLINT
+		qCritical().nospace() << "Failed to set daemon stdout to /dev/null" << errno << ": "
+		                      << qt_error_string();
 	}
+
+	if (dup2(fd, STDERR_FILENO) != STDERR_FILENO) { // NOLINT
+		qCritical().nospace() << "Failed to set daemon stderr to /dev/null" << errno << ": "
+		                      << qt_error_string();
+	}
+
+	close(fd);
 }
 
 int main(int argc, char** argv) {