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Activate the sigevents inside the signal pipe callback itself

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and call signal_pipe_cb() directly if the backend returns EINTR
and the signal_caught flag is set.  This has the side effect of
processing signal events in the current pass of the event loop
instead of the next one.
This commit is contained in:
Todd C. Miller
2017-05-12 10:02:17 -06:00
parent 1186f39842
commit 95e92bfe4e
1 changed files with 23 additions and 19 deletions
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42
lib/util/event.c
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@@ -86,20 +86,15 @@ sudo_ev_deactivate_all(struct sudo_event_base *base)
/*
* Activate all signal events for which the corresponding signal_pending[]
* flag is set.
* Returns true if at least one sigevent has been activated.
*/
static bool
static void
sudo_ev_activate_sigevents(struct sudo_event_base *base)
{
struct sudo_event *ev;
sigset_t set, oset;
bool ret = false;
int i;
debug_decl(sudo_ev_activate_sigevents, SUDO_DEBUG_EVENT)
if (base->signal_caught == 0)
debug_return_bool(false);
/*
* We treat this as a critical section since the signal handler
* could modify the siginfo[] entry.
@@ -126,12 +121,11 @@ sudo_ev_activate_sigevents(struct sudo_event_base *base)
ev->revents = ev->events & (SUDO_EV_SIGNAL|SUDO_EV_SIGINFO);
TAILQ_INSERT_TAIL(&base->active, ev, active_entries);
SET(ev->flags, SUDO_EVQ_ACTIVE);
ret = true;
}
}
sigprocmask(SIG_SETMASK, &oset, NULL);
debug_return_bool(ret);
debug_return;
}
/*
@@ -140,15 +134,29 @@ sudo_ev_activate_sigevents(struct sudo_event_base *base)
static void
signal_pipe_cb(int fd, int what, void *v)
{
struct sudo_event_base *base = v;
unsigned char ch;
ssize_t nread;
debug_decl(signal_pipe_cb, SUDO_DEBUG_EVENT)
/*
* Drain signal_pipe, the signal handler updated base->signals_pending.
* Actual processing of signal events is done when poll/select is
* interrupted by a signal.
*/
while (read(fd, &ch, 1) > 0)
continue;
while ((nread = read(fd, &ch, 1)) > 0) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: received signal %d", __func__, (int)ch);
}
if (nread == -1 && errno != EAGAIN) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO|SUDO_DEBUG_ERRNO,
"%s: error reading from signal pipe", __func__);
}
/* Activate signal events. */
sudo_ev_activate_sigevents(base);
debug_return;
}
struct sudo_event_base *
@@ -179,7 +187,7 @@ sudo_ev_base_alloc_v1(void)
goto bad;
}
sudo_ev_init(&base->signal_event, base->signal_pipe[1],
SUDO_EV_READ|SUDO_EV_PERSIST, signal_pipe_cb, NULL);
SUDO_EV_READ|SUDO_EV_PERSIST, signal_pipe_cb, base);
debug_return_ptr(base);
bad:
@@ -306,10 +314,7 @@ sudo_ev_handler(int signo, siginfo_t *info, void *context)
signal_base->signal_caught = 1;
/* Wake up the other end of the pipe. */
while (write(signal_base->signal_pipe[0], &ch, 1) == -1) {
if (errno != EINTR)
break;
}
ignore_result(write(signal_base->signal_pipe[0], &ch, 1));
}
}
@@ -586,8 +591,10 @@ rescan:
continue;
if (errno == EINTR) {
/* Interrupted by signal, check for sigevents. */
if (sudo_ev_activate_sigevents(base))
if (base->signal_caught) {
signal_pipe_cb(base->signal_pipe[1], SUDO_EV_READ, base);
break;
}
continue;
}
rc = -1;
@@ -617,9 +624,6 @@ rescan:
break;
}
/* Activate signal events, if any. */
sudo_ev_activate_sigevents(base);
/*
* Service each event in the active queue.
* We store the current event pointer in the base so that