Github user sanhex commented on a diff in the pull request:
https://github.com/apache/incubator-guacamole-server/pull/118#discussion_r145826455
--- Diff: src/protocols/ssh/client.c ---
@@ -70,8 +70,14 @@ int guac_ssh_client_free_handler(guac_client* client) {
/* Free terminal (which may still be using term_channel) */
if (ssh_client->term != NULL) {
- guac_terminal_free(ssh_client->term);
+ /* Close user input pipe to stop reading in ssh_input_thread */
+ close(ssh_client->term->stdin_pipe_fd[1]);
+ close(ssh_client->term->stdin_pipe_fd[0]);
+ ssh_client->term->stdin_pipe_fd[1] = -1;
+ ssh_client->term->stdin_pipe_fd[0] = -1;
+
--- End diff --
I agree this looks really ugly. But if I don't close the pipe here, there
will be a dead lock in this case.
The thread here will be waiting for ssh_client_thread() by calling
pthread_join(ssh_client->client_thread, NULL), ssh_client_thread() will be
waiting for ssh_input_thread(). ssh_input_thread() will be blocked by
guac_terminal_read_stdin() show below.
https://github.com/sanhex/incubator-guacamole-server/blob/c6cb1910e3580f9c21fc202f824fc55c95a43e49/src/protocols/ssh/ssh.c#L161
The child process of guacd will never exit after disconnecting the ssh
connection. I met this problem.. So I manually closed the pipe to stop the
ssh_input_thread() mentioned above.
---
