lib-master: Replace listeners with /dev/null in SIGQUIT instead of closing

This should be somewhat safer.

diff --git a/src/lib-master/master-service-private.h b/src/lib-master/master-service-private.h
index 7c9a820f1eee056553186dd95888c322fd6b9d3f..b585e38c560f6056c2ed87bf4c506cba8304bc34 100644 (file)
--- a/src/lib-master/master-service-private.h
+++ b/src/lib-master/master-service-private.h
@@ -15,6 +15,7 @@ struct master_service_listener {
        bool haproxy;
 
        /* state */
+       bool closed;
        int fd; 
        struct io *io;
 };

diff --git a/src/lib-master/master-service.c b/src/lib-master/master-service.c
index b37cfc5f8bbeb50e7705fef22e7bc14b25cdde8b..b5e92f9101e6a044269a927725ee7d698dc307c2 100644 (file)
--- a/src/lib-master/master-service.c
+++ b/src/lib-master/master-service.c
@@ -95,13 +95,17 @@ static void sig_close_listeners(const siginfo_t *si ATTR_UNUSED, void *context)
           that don't have an io, but this shouldn't be a big problem. If there
           is an active io, the service is unlikely to be unresposive for
           longer periods of time, so the listener gets closed soon enough via
-          master_status_error(). */
+          master_status_error().
+
+          For extra safety we don't actually close() the fd, but instead
+          replace it with /dev/null. This way it won't be replaced with some
+          other new fd and attempted to be used in unexpected ways. */
        for (unsigned int i = 0; i < service->socket_count; i++) {
                if (service->listeners[i].fd != -1 &&
                    service->listeners[i].io == NULL) {
-                       if (close(service->listeners[i].fd) < 0)
-                               lib_signals_syscall_error("signal: close(listener) failed: ");
-                       service->listeners[i].fd = -1;
+                       if (dup2(dev_null_fd, service->listeners[i].fd) < 0)
+                               lib_signals_syscall_error("signal: dup2(/dev/null, listener) failed: ");
+                       service->listeners[i].closed = TRUE;
                }
        }
 }
@@ -1007,7 +1011,7 @@ void master_service_io_listeners_add(struct master_service *service)
        for (i = 0; i < service->socket_count; i++) {
                struct master_service_listener *l = &service->listeners[i];
 
-               if (l->io == NULL && l->fd != -1) {
+               if (l->io == NULL && l->fd != -1 && !l->closed) {
                        l->io = io_add(MASTER_LISTEN_FD_FIRST + i, IO_READ,
                                       master_service_listen, l);
                }