问题
These two functions are both infinite loops,
and the programe hangs once called in the same thread.
gtk_main();
...
pcap_loop(adhandle, 0, packet_handler, NULL);
When I click the "start" button,I want pcap to start working;And if I press the "stop" button,pcap stop.
How do I create a child thread and run pcap_loop(adhandle, 0, packet_handler, NULL); instead?
回答1:
Unless I am missing something, your problem is that both GTK+ and
libpcap are organized around events fired from a main loop. Without
looking through the documentation, I don't know about GTK+, but there
is another mode of operation for libpcap: You can use pcap_next() or
pcap_next_ex() without giving up control over your program flow.
It should be possible to register a function that periodically calls
one of these two functions using g_timeout_add() or g_idle_add(),
removing the need to mess around with threads and mutex mechanisms
altogether.
回答2:
Take a look at the documentation for g_thread_create(). Also read this tutorial and this blog post for more information on multithreaded GTK programs.
Basically you'll want to call gtk_main() first when you've built your user interface and started your program. Then in the callback for the "start" button, create a new thread with g_thread_create() in which you call pcap_loop().
The "stop" button is a little more difficult since GLib doesn't allow you to interrupt a thread from a different thread. You'll have to create some signaling mechanism; for example, a boolean abort flag protected by a GMutex. In your stop button callback, lock the flag with g_mutex_lock(), set it, and unlock it with g_mutex_unlock(). In your packet_handler, also lock the flag, read it, and unlock it. If the flag was set, then call whatever it is you call to make pcap break out of the loop.
来源：https://stackoverflow.com/questions/2793293/how-do-i-create-a-new-thread-to-make-pcap-loop-and-gtk-main-compatible