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Code Issues Releases Wiki Activity

Being more careful with signals to avoid deadlocks

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This commit is contained in:
Nicolas Viennot 2016-01-22 13:17:57 -05:00
parent 9fe781453d
commit 23bbaab3d2
2 changed files with 43 additions and 50 deletions
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6
tmate-slave.c
View File

@ -316,6 +316,11 @@ static void setup_ncurse(int fd, const char *name)
tmate_fatal("Cannot setup terminal");
}
static void handle_sigterm(__unused int sig)
{
request_server_termination();
}
static void tmate_spawn_slave_daemon(struct tmate_session *session)
{
struct tmate_ssh_client *client = &session->ssh_client;
@ -355,6 +360,7 @@ static void tmate_spawn_slave_daemon(struct tmate_session *session)
event_reinit(session->ev_base);
tmux_server_init();
signal(SIGTERM, handle_sigterm);
server_start(session->ev_base, -1, NULL);
/* never reached */
}

87
tmate-ssh-server.c
View File

@ -169,6 +169,11 @@ static void register_on_ssh_read(struct tmate_ssh_client *client)
event_add(&client->ev_ssh, NULL);
}
static void handle_sigalrm(__unused int sig)
{
tmate_fatal("Connection grace period (%d) passed", TMATE_SSH_GRACE_PERIOD);
}
static void client_bootstrap(struct tmate_session *_session)
{
struct tmate_ssh_client *client = &_session->ssh_client;
@ -187,6 +192,7 @@ static void client_bootstrap(struct tmate_session *_session)
setsockopt(ssh_get_fd(session), IPPROTO_TCP, TCP_NODELAY,
&flag, sizeof(flag));
signal(SIGALRM, handle_sigalrm);
alarm(grace_period);
/*
@ -228,55 +234,6 @@ static void client_bootstrap(struct tmate_session *_session)
/* never reached */
}
static void handle_sigchld(void)
{
int status;
pid_t pid;
while ((pid = waitpid(WAIT_ANY, &status, WNOHANG)) > 0) {
if (WIFEXITED(status))
tmate_info("Child %d exited (%d)", pid, WEXITSTATUS(status));
if (WIFSIGNALED(status))
tmate_info("Child %d killed (%d)", pid, WTERMSIG(status));
if (WIFSTOPPED(status))
tmate_info("Child %d stopped (%d)", pid, WSTOPSIG(status));
}
}
static void handle_sigalrm(void)
{
tmate_fatal("Connection grace period (%d) passed", TMATE_SSH_GRACE_PERIOD);
}
static void handle_sigsegv(void)
{
tmate_info("CRASH, printing stack trace");
tmate_print_stack_trace();
tmate_fatal("CRASHED");
}
static void handle_sigterm(void)
{
request_server_termination();
}
static void signal_handler(int sig)
{
switch (sig) {
case SIGTERM: handle_sigterm(); break;
case SIGCHLD: handle_sigchld(); break;
case SIGALRM: handle_sigalrm(); break;
case SIGSEGV: handle_sigsegv(); break;
}
}
static void setup_signals(void)
{
signal(SIGTERM, signal_handler);
signal(SIGCHLD, signal_handler);
signal(SIGALRM, signal_handler);
signal(SIGSEGV, signal_handler);
}
static int get_ip(int fd, char *dst, size_t len)
{
struct sockaddr sa;
@ -340,14 +297,42 @@ static ssh_bind prepare_ssh(const char *keys_dir, int port)
return bind;
}
static void handle_sigchld(__unused int sig)
{
int status;
pid_t pid;
while ((pid = waitpid(WAIT_ANY, &status, WNOHANG)) > 0) {
if (WIFEXITED(status))
tmate_info("Child %d exited (%d)", pid, WEXITSTATUS(status));
if (WIFSIGNALED(status))
tmate_info("Child %d killed (%d)", pid, WTERMSIG(status));
if (WIFSTOPPED(status))
tmate_info("Child %d stopped (%d)", pid, WSTOPSIG(status));
}
}
static void handle_sigsegv(__unused int sig)
{
tmate_info("CRASH, printing stack trace");
tmate_print_stack_trace();
tmate_fatal("CRASHED");
}
void tmate_ssh_server_main(struct tmate_session *session,
const char *keys_dir, int port)
{
sigset_t sigchld_set;
struct tmate_ssh_client *client = &session->ssh_client;
ssh_bind bind;
pid_t pid;
setup_signals();
signal(SIGSEGV, handle_sigsegv);
signal(SIGCHLD, handle_sigchld);
sigemptyset(&sigchld_set);
sigaddset(&sigchld_set, SIGCHLD);
sigprocmask(SIG_BLOCK, &sigchld_set, NULL);
bind = prepare_ssh(keys_dir, port);
@ -360,8 +345,10 @@ void tmate_ssh_server_main(struct tmate_session *session,
if (!client->session)
tmate_fatal("Cannot initialize session");
sigprocmask(SIG_UNBLOCK, &sigchld_set, NULL);
if (ssh_bind_accept(bind, client->session) < 0)
tmate_fatal("Error accepting connection: %s", ssh_get_error(bind));
sigprocmask(SIG_BLOCK, &sigchld_set, NULL);
if (get_ip(ssh_get_fd(client->session),
client->ip_address, sizeof(client->ip_address)) < 0)