lib/tevent: handle tevent_common_add_signal on different event contexts.

I don't know if this is a problem in real life.

The code assumes there's only one tevent_context; all signals will notify
the first event context.  That's counter-intuitive if you ever use more
than one, and there's nothing else in this code which prevents it AFAICT.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
(cherry picked from commit be4ac227842530d484659f2db683453366326d8b)

diff --git a/lib/tevent/tevent_internal.h b/lib/tevent/tevent_internal.h
index b3798646010cbae829605588a465a50fa1fc65c1..aa7c34aa89bbe9796bad05d6049d93774cebbdd9 100644 (file)
--- a/lib/tevent/tevent_internal.h
+++ b/lib/tevent/tevent_internal.h
@@ -240,6 +240,7 @@ struct tevent_context {
 
        /* pipe hack used with signal handlers */
        struct tevent_fd *pipe_fde;
+       int pipe_fds[2];
 
        /* debugging operations */
        struct tevent_debug_ops debug_ops;

diff --git a/lib/tevent/tevent_signal.c b/lib/tevent/tevent_signal.c
index 2c87463b95de50fb5ed05df1f9344b9bc9612d1c..0333325ef0f3de3a3fcd39aac5e7ff6368b505e3 100644 (file)
--- a/lib/tevent/tevent_signal.c
+++ b/lib/tevent/tevent_signal.c
@@ -57,7 +57,6 @@ static struct sig_state {
        struct sigaction *oldact[NUM_SIGNALS+1];
        struct sigcounter signal_count[NUM_SIGNALS+1];
        struct sigcounter got_signal;
-       int pipe_hack[2];
 #ifdef SA_SIGINFO
        /* with SA_SIGINFO we get quite a lot of info per signal */
        siginfo_t *sig_info[NUM_SIGNALS+1];
@@ -80,10 +79,20 @@ static void tevent_common_signal_handler(int signum)
 {
        char c = 0;
        ssize_t res;
+       struct tevent_common_signal_list *sl;
+       struct tevent_context *ev = NULL;
+
        SIG_INCREMENT(sig_state->signal_count[signum]);
        SIG_INCREMENT(sig_state->got_signal);
-       /* doesn't matter if this pipe overflows */
-       res = write(sig_state->pipe_hack[1], &c, 1);
+
+       /* Write to each unique event context. */
+       for (sl = sig_state->sig_handlers[signum]; sl; sl = sl->next) {
+               if (sl->se->event_ctx != ev) {
+                       /* doesn't matter if this pipe overflows */
+                       res = write(ev->pipe_fds[1], &c, 1);
+                       ev = sl->se->event_ctx;
+               }
+       }
 }
 
 #ifdef SA_SIGINFO
@@ -160,7 +169,7 @@ static void signal_pipe_handler(struct tevent_context *ev, struct tevent_fd *fde
        char c[16];
        ssize_t res;
        /* its non-blocking, doesn't matter if we read too much */
-       res = read(sig_state->pipe_hack[0], c, sizeof(c));
+       res = read(fde->fd, c, sizeof(c));
 }
 
 /*
@@ -178,6 +187,7 @@ struct tevent_signal *tevent_common_add_signal(struct tevent_context *ev,
 {
        struct tevent_signal *se;
        struct tevent_common_signal_list *sl;
+       sigset_t set, oldset;
 
        if (signum >= NUM_SIGNALS) {
                errno = EINVAL;
@@ -222,18 +232,18 @@ struct tevent_signal *tevent_common_add_signal(struct tevent_context *ev,
        /* we need to setup the pipe hack handler if not already
           setup */
        if (ev->pipe_fde == NULL) {
-               if (sig_state->pipe_hack[0] == 0 &&
-                   sig_state->pipe_hack[1] == 0) {
-                       if (pipe(sig_state->pipe_hack) == -1) {
-                               talloc_free(se);
-                               return NULL;
-                       }
-                       ev_set_blocking(sig_state->pipe_hack[0], false);
-                       ev_set_blocking(sig_state->pipe_hack[1], false);
+               if (pipe(ev->pipe_fds) == -1) {
+                       talloc_free(se);
+                       return NULL;
                }
-               ev->pipe_fde = tevent_add_fd(ev, ev, sig_state->pipe_hack[0],
-                                            TEVENT_FD_READ, signal_pipe_handler, NULL);
+               ev_set_blocking(ev->pipe_fds[0], false);
+               ev_set_blocking(ev->pipe_fds[1], false);
+               ev->pipe_fde = tevent_add_fd(ev, ev, ev->pipe_fds[0],
+                                            TEVENT_FD_READ,
+                                            signal_pipe_handler, NULL);
                if (!ev->pipe_fde) {
+                       close(ev->pipe_fds[0]);
+                       close(ev->pipe_fds[1]);
                        talloc_free(se);
                        return NULL;
                }
@@ -270,7 +280,13 @@ struct tevent_signal *tevent_common_add_signal(struct tevent_context *ev,
        }
 
        DLIST_ADD(se->event_ctx->signal_events, se);
+
+       /* Make sure the signal doesn't come in while we're mangling list. */
+       sigemptyset(&set);
+       sigaddset(&set, signum);
+       sigprocmask(SIG_BLOCK, &set, &oldset);
        DLIST_ADD(sig_state->sig_handlers[signum], sl);
+       sigprocmask(SIG_SETMASK, &oldset, NULL);
 
        talloc_set_destructor(se, tevent_signal_destructor);
        talloc_set_destructor(sl, tevent_common_signal_list_destructor);