+slots_read(Config *cfg, struct timespec *ti, char *buf)
+{
+ fd_set fds;
+ int maxfd = -1;
+ int ready = 0;
+ struct stat st;
+ struct timespec t;
+ Slot *s;
+
+ FD_ZERO(&fds);
+ for (s = cfg->slots; s; s = s->next) {
+ /* TODO: Create the FIFO if it doesn't already exist. */
+ if (lstat(s->in_fifo, &st) < 0) {
+ khlib_error(
+ "Cannot stat \"%s\". Error: %s\n",
+ s->in_fifo,
+ strerror(errno)
+ );
+ slot_set_error(s, buf);
+ continue;
+ }
+ if (!(st.st_mode & S_IFIFO)) {
+ khlib_error("\"%s\" is not a FIFO\n", s->in_fifo);
+ slot_set_error(s, buf);
+ continue;
+ }
+ if (s->in_fd < 0) {
+ khlib_debug(
+ "%s: closed. opening. in_fd: %d\n",
+ s->in_fifo,
+ s->in_fd
+ );
+ s->in_fd = open(s->in_fifo, O_RDONLY | O_NONBLOCK);
+ } else {
+ khlib_debug(
+ "%s: already openned. in_fd: %d\n",
+ s->in_fifo,
+ s->in_fd
+ );
+ }
+ if (s->in_fd == -1) {
+ /* TODO Consider backing off retries for failed slots */
+ khlib_error("Failed to open \"%s\"\n", s->in_fifo);
+ slot_set_error(s, buf);
+ continue;
+ }
+ khlib_debug("%s: open. in_fd: %d\n", s->in_fifo, s->in_fd);
+ if (s->in_fd > maxfd)
+ maxfd = s->in_fd;
+ FD_SET(s->in_fd, &fds);
+ }
+ khlib_debug("selecting...\n");
+ ready = pselect(maxfd + 1, &fds, NULL, NULL, ti, NULL);
+ khlib_debug("ready: %d\n", ready);
+ clock_gettime(CLOCK_MONOTONIC, &t);
+ if (ready == -1) {
+ switch (errno) {
+ case EINTR:
+ khlib_error(
+ "pselect interrupted: %d, errno: %d, msg: %s\n",
+ ready,
+ errno,
+ strerror(errno)
+ );
+ /* TODO: Reconsider what to do here. */
+ return;
+ default:
+ khlib_fatal(
+ "pselect failed: %d, errno: %d, msg: %s\n",
+ ready,
+ errno,
+ strerror(errno)
+ );
+ }
+ }
+ /* At-least-once ensures that expiries are still checked on timeouts. */
+ do {
+ for (s = cfg->slots; s; s = s->next) {
+ if (s->in_fd < 0)
+ continue;
+ if (FD_ISSET(s->in_fd, &fds)) {
+ khlib_debug("reading: %s\n", s->in_fifo);
+ switch (slot_read(s, buf)) {
+ /*
+ * ### MESSAGE LOSS ###
+ * is introduced by closing at EOM in addition
+ * to EOF, since there may be unread messages
+ * remaining in the pipe. However,
+ *
+ * ### INTER-MESSAGE PUSHBACK ###
+ * is also gained, since pipes block at the
+ * "open" call.
+ *
+ * This is an acceptable trade-off because we
+ * are a stateless reporter of a _most-recent_
+ * status, not a stateful accumulator.
+ *
+ * ### LOSSLESS ALTERNATIVES ###
+ * - Read each pipe until EOF before reading
+ * another.
+ * PROBLEM: a fast writer can trap us in the
+ * read loop.
+ *
+ * - Read each pipe until EOM, but close only
+ * at EOF.
+ * PROBLEM: a fast writer can fill the pipe
+ * faster than we can read it and we end-up
+ * displaying stale data.
+ *
+ */
+ case END_OF_MESSAGE:
+ case END_OF_FILE:
+ case FAILURE:
+ slot_close(s);
+ s->in_last_read = t;
+ ready--;
+ break;
+ case RETRY:
+ break;
+ default:
+ assert(0);
+ }
+ } else {
+ slot_expire(s, t, cfg->expiry_character, buf);
+ }
+ }
+ } while (ready);
+ assert(ready == 0);
+}
+
+void
+config_log(Config *cfg)