Function fcntl

src/platforms/win/socket_win.cpp.hpp:278–298

fcntl emulation for non-blocking sockets

// fcntl emulation for non-blocking sockets
int fcntl(int fd, int cmd, ...) FL_NOEXCEPT {
    SOCKET sock = static_cast<SOCKET>(fd);
    
    if (cmd == F_GETFL) {
        // Windows doesn't provide a way to query non-blocking status
        // Return 0 (blocking) as default
        return 0;
    } else if (cmd == F_SETFL) {
        va_list args;
        va_start(args, cmd);
        int flags = va_arg(args, int);
        va_end(args);
        
        u_long mode = (flags & O_NONBLOCK) ? 1 : 0;
        int result = ioctlsocket(sock, FIONBIO, &mode);
        return (result == SOCKET_ERROR) ? -1 : 0;
    }
    
    WSASetLastError(WSAEINVAL);
    return -1;
}

// Note: get_errno() is provided by fl/stl/cerrno.h
// Note: Platform abstraction functions (create_platform_socket, etc.) are not needed