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https://issues.apache.org/jira/browse/GUACAMOLE-1625?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17557771#comment-17557771
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luo commented on GUACAMOLE-1625:
--------------------------------
I don't have any good ideas either
"which seems like it may be hard/expensive to determine which ones are safe to
close and which need to remain open"
The answer is that all fd's opened by the first guacd cannot be closed (usually
fd's less than 10), the rest can be closed
We just close the fd less than 10 after fork
in proc.c
{code:java}
guacd_proc* guacd_create_proc(const char* protocol) {
int sockets[2];
/* Open UNIX socket pair */
if (socketpair(AF_UNIX, SOCK_DGRAM, 0, sockets) < 0) {
guacd_log(GUAC_LOG_ERROR, "Error opening socket pair: %s",
strerror(errno));
return NULL;
}
...................
proc->pid = fork();
if (proc->pid < 0) {
guacd_log(GUAC_LOG_ERROR, "Cannot fork child process: %s",
strerror(errno));
close(parent_socket);
close(child_socket);
guac_client_free(proc->client);
free(proc);
return NULL;
} /* Child */
else if (proc->pid == 0) {
/***************
Close all fd's except for those less than 10 and the "sockets[2]" created
earlier
***************/
proc->fd_socket = parent_socket;
close(child_socket);
guacd_exec_proc(proc, protocol);
}
...................
} {code}
This is not a very standardized way to write code
> Child processes inherit useless fd from parent processes
> --------------------------------------------------------
>
> Key: GUACAMOLE-1625
> URL: https://issues.apache.org/jira/browse/GUACAMOLE-1625
> Project: Guacamole
> Issue Type: Improvement
> Components: guacd
> Affects Versions: 1.4.0
> Reporter: luo
> Priority: Minor
>
> For example, if we open three ssh connections in a row, the subprocesses will
> have more and more fd, which is actually not necessary
> Most fd's come from the socketpair() of the parent process
>
> {code:java}
> # ps aux | grep guacd
> root 6453 0.0 0.3 522844 14756 pts/0 Sl+ 19:24 0:00 guacd -f
> -Ldebug
> root 6457 0.2 0.9 628436 37176 pts/0 Sl 19:24 0:00 guacd -f
> -Ldebug
> root 6512 1.8 0.9 483508 38644 pts/0 Sl 19:31 0:00 guacd -f
> -Ldebug
> root 6605 0.0 0.0 21540 1084 pts/2 S+ 19:31 0:00 grep
> --color=auto guacd
> # cd /proc/6512/fd
> # ls
> 0 1 10 11 12 13 14 2 3 4 5 6 7 8 9
> # ps aux | grep guacd
> root 6453 0.0 0.3 678504 14756 pts/0 Sl+ 19:24 0:00 guacd -f
> -Ldebug
> root 6457 0.1 0.9 628436 37176 pts/0 Sl 19:24 0:00 guacd -f
> -Ldebug
> root 6512 0.2 0.9 483508 38752 pts/0 Sl 19:31 0:00 guacd -f
> -Ldebug
> root 6620 5.0 0.9 679600 38748 pts/0 Sl 19:31 0:00 guacd -f
> -Ldebug
> root 6713 0.0 0.0 21540 1104 pts/2 S+ 19:31 0:00 grep
> --color=auto guacd
> # cd /proc/6620/fd
> # ls
> 0 1 10 11 12 13 14 15 16 17 2 3 4 5 6 7 8 9
> # ps aux | grep guacd
> root 6453 0.0 0.3 703092 14756 pts/0 Sl+ 19:24 0:00 guacd -f
> -Ldebug
> root 6457 0.1 0.9 628436 37176 pts/0 Sl 19:24 0:00 guacd -f
> -Ldebug
> root 6512 0.1 0.9 483508 38752 pts/0 Sl 19:31 0:00 guacd -f
> -Ldebug
> root 6620 0.3 0.9 679600 38748 pts/0 Sl 19:31 0:00 guacd -f
> -Ldebug
> root 6720 1.2 0.9 761528 38804 pts/0 Sl 19:31 0:00 guacd -f
> -Ldebug
> root 6813 0.0 0.0 21540 1148 pts/2 S+ 19:31 0:00 grep
> --color=auto guacd
> # cd /proc/6720/fd
> # ls
> 0 1 10 11 12 13 14 15 16 17 18 19 2 20 3 4 5 6 7 8 9
> {code}
> This may cause libvncserver to fail using select() if the useless fd is
> larger than FD_SETSIZE
>
>
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