Converting the former BFD loop to a universal IO loop and protocol loop.

There is a simple universal IO loop, taking care of events, timers and
sockets. Primarily, one instance of a protocol should use exactly one IO
loop to do all its work, as is now done in BFD.

Contrary to previous versions, the loop is now launched and cleaned by
the nest/proto.c code, allowing for a protocol to just request its own
loop by setting the loop's lock order in config higher than the_bird.

It is not supported nor checked if any protocol changed the requested
lock order in reconfigure. No protocol should do it at all.

6 files changed, 266 insertions, 200 deletions

diff --git a/sysdep/unix/coroutine.c b/sysdep/unix/coroutine.c
index 2eba142c..4758c056 100644
--- a/sysdep/unix/coroutine.c
+++ b/sysdep/unix/coroutine.c
@@ -21,10 +21,9 @@
 #include "lib/resource.h"
 #include "lib/timer.h"
 
-/* Using a rather big stack for coroutines to allow for stack-local allocations.
- * In real world, the kernel doesn't alloc this memory until it is used.
- * */
-#define CORO_STACK_SIZE	1048576
+#include "conf/conf.h"
+
+#define CORO_STACK_SIZE	65536
 
 /*
  *	Implementation of coroutines based on POSIX threads
@@ -79,6 +78,11 @@ domain_free(struct domain_generic *dg)
   xfree(dg);
 }
 
+uint dg_order(struct domain_generic *dg)
+{
+  return dg->order;
+}
+
 void do_lock(struct domain_generic *dg, struct domain_generic **lsp)
 {
   if ((char *) lsp - (char *) &locking_stack != dg->order)
@@ -89,7 +93,11 @@ void do_lock(struct domain_generic *dg, struct domain_generic **lsp)
   if (*lsp)
     bug("Inconsistent locking stack state on lock");
 
+  btime lock_begin = current_time();
   pthread_mutex_lock(&dg->mutex);
+  btime duration = current_time() - lock_begin;
+  if (config && (duration > config->watchdog_warning))
+    log(L_WARN "Locking of %s took %d ms", dg->name, (int) (duration TO_MS));
 
   if (dg->prev || dg->locked_by)
     bug("Previous unlock not finished correctly");
@@ -140,11 +148,16 @@ static struct resclass coro_class = {
   .free = coro_free,
 };
 
+_Thread_local struct coroutine *this_coro = NULL;
+
 static void *coro_entry(void *p)
 {
   struct coroutine *c = p;
+
   ASSERT_DIE(c->entry);
 
+  this_coro = c;
+
   c->entry(c->data);
   ASSERT_DIE(coro_cleaned_up);
 
diff --git a/sysdep/unix/io-loop.c b/sysdep/unix/io-loop.c
index a15d866a..275d38a0 100644
--- a/sysdep/unix/io-loop.c
+++ b/sysdep/unix/io-loop.c
@@ -15,50 +15,47 @@
 #include <sys/time.h>
 
 #include "nest/bird.h"
-#include "sysdep/unix/io-loop.h"
 
 #include "lib/buffer.h"
+#include "lib/coro.h"
 #include "lib/lists.h"
 #include "lib/resource.h"
 #include "lib/event.h"
 #include "lib/timer.h"
 #include "lib/socket.h"
 
-
-struct birdloop
-{
-  pool *pool;
-  pthread_t thread;
-  pthread_mutex_t mutex;
-
-  u8 stop_called;
-  u8 poll_active;
-  u8 wakeup_masked;
-  int wakeup_fds[2];
-
-  struct timeloop time;
-  list event_list;
-  list sock_list;
-  uint sock_num;
-
-  BUFFER(sock *) poll_sk;
-  BUFFER(struct pollfd) poll_fd;
-  u8 poll_changed;
-  u8 close_scheduled;
-};
-
+#include "lib/io-loop.h"
+#include "sysdep/unix/io-loop.h"
+#include "conf/conf.h"
 
 /*
  *	Current thread context
  */
 
-static _Thread_local struct birdloop *birdloop_current;
+_Thread_local struct birdloop *birdloop_current;
+static _Thread_local struct birdloop *birdloop_wakeup_masked;
+static _Thread_local uint birdloop_wakeup_masked_count;
 
-static inline void
-birdloop_set_current(struct birdloop *loop)
+event_list *
+birdloop_event_list(struct birdloop *loop)
 {
-  birdloop_current = loop;
-  local_timeloop = loop ? &loop->time : &main_timeloop;
+  return &loop->event_list;
+}
+
+struct timeloop *
+birdloop_time_loop(struct birdloop *loop)
+{
+  return &loop->time;
+}
+
+_Bool
+birdloop_inside(struct birdloop *loop)
+{
+  for (struct birdloop *c = birdloop_current; c; c = c->prev_loop)
+    if (loop == c)
+      return 1;
+
+  return 0;
 }
 
 /*
@@ -135,57 +132,17 @@ wakeup_do_kick(struct birdloop *loop)
   pipe_kick(loop->wakeup_fds[1]);
 }
 
-static inline void
-wakeup_kick(struct birdloop *loop)
-{
-  if (!loop->wakeup_masked)
-    wakeup_do_kick(loop);
-  else
-    loop->wakeup_masked = 2;
-}
-
-/* For notifications from outside */
 void
-wakeup_kick_current(void)
+birdloop_ping(struct birdloop *loop)
 {
-  if (birdloop_current && birdloop_current->poll_active)
-    wakeup_kick(birdloop_current);
-}
-
-
-/*
- *	Events
- */
+  u32 ping_sent = atomic_fetch_add_explicit(&loop->ping_sent, 1, memory_order_acq_rel);
+  if (ping_sent)
+    return;
 
-static inline uint
-events_waiting(struct birdloop *loop)
-{
-  return !EMPTY_LIST(loop->event_list);
-}
-
-static inline void
-events_init(struct birdloop *loop)
-{
-  init_list(&loop->event_list);
-}
-
-static void
-events_fire(struct birdloop *loop)
-{
-  times_update();
-  ev_run_list(&loop->event_list);
-}
-
-void
-ev2_schedule(event *e)
-{
-  if (birdloop_current->poll_active && EMPTY_LIST(birdloop_current->event_list))
-    wakeup_kick(birdloop_current);
-
-  if (e->n.next)
-    rem_node(&e->n);
-
-  add_tail(&birdloop_current->event_list, &e->n);
+  if (loop == birdloop_wakeup_masked)
+    birdloop_wakeup_masked_count++;
+  else
+    wakeup_do_kick(loop);
 }
 
 
@@ -213,13 +170,13 @@ sockets_add(struct birdloop *loop, sock *s)
   s->index = -1;
   loop->poll_changed = 1;
 
-  if (loop->poll_active)
-    wakeup_kick(loop);
+  birdloop_ping(loop);
 }
 
 void
 sk_start(sock *s)
 {
+  ASSERT_DIE(birdloop_current != &main_birdloop);
   sockets_add(birdloop_current, s);
 }
 
@@ -230,28 +187,21 @@ sockets_remove(struct birdloop *loop, sock *s)
   loop->sock_num--;
 
   if (s->index >= 0)
+  {
     loop->poll_sk.data[s->index] = NULL;
-
-  s->index = -1;
-  loop->poll_changed = 1;
-
-  /* Wakeup moved to sk_stop() */
+    s->index = -1;
+    loop->poll_changed = 1;
+    loop->close_scheduled = 1;
+    birdloop_ping(loop);
+  }
+  else
+    close(s->fd);
 }
 
 void
 sk_stop(sock *s)
 {
   sockets_remove(birdloop_current, s);
-
-  if (birdloop_current->poll_active)
-  {
-    birdloop_current->close_scheduled = 1;
-    wakeup_kick(birdloop_current);
-  }
-  else
-    close(s->fd);
-
-  s->fd = -1;
 }
 
 static inline uint sk_want_events(sock *s)
@@ -351,12 +301,15 @@ sockets_fire(struct birdloop *loop)
 
     if (pfd->revents & POLLIN)
       while (e && *psk && (*psk)->rx_hook)
-	e = sk_read(*psk, 0);
+	e = sk_read(*psk, pfd->revents);
 
     e = 1;
     if (pfd->revents & POLLOUT)
+    {
+      loop->poll_changed = 1;
       while (e && *psk)
 	e = sk_write(*psk);
+    }
   }
 }
 
@@ -365,104 +318,168 @@ sockets_fire(struct birdloop *loop)
  *	Birdloop
  */
 
-static void *birdloop_main(void *arg);
+struct birdloop main_birdloop;
+
+static void birdloop_enter_locked(struct birdloop *loop);
+
+void
+birdloop_init(void)
+{
+  wakeup_init(&main_birdloop);
+
+  main_birdloop.time.domain = the_bird_domain.the_bird;
+  main_birdloop.time.loop = &main_birdloop;
+
+  times_update();
+  timers_init(&main_birdloop.time, &root_pool);
+
+  birdloop_enter_locked(&main_birdloop);
+}
+
+static void birdloop_main(void *arg);
 
 struct birdloop *
-birdloop_new(void)
+birdloop_new(pool *pp, uint order, const char *name)
 {
-  pool *p = rp_new(NULL, "Birdloop root");
+  struct domain_generic *dg = domain_new(name, order);
+
+  pool *p = rp_new(pp, name);
   struct birdloop *loop = mb_allocz(p, sizeof(struct birdloop));
   loop->pool = p;
-  pthread_mutex_init(&loop->mutex, NULL);
 
-  wakeup_init(loop);
+  loop->time.domain = dg;
+  loop->time.loop = loop;
+
+  birdloop_enter(loop);
 
-  events_init(loop);
+  wakeup_init(loop);
+  ev_init_list(&loop->event_list, loop, name);
   timers_init(&loop->time, p);
   sockets_init(loop);
 
+  loop->time.coro = coro_run(p, birdloop_main, loop);
+
+  birdloop_leave(loop);
+
   return loop;
 }
 
+static void
+birdloop_do_stop(struct birdloop *loop, void (*stopped)(void *data), void *data)
+{
+  loop->stopped = stopped;
+  loop->stop_data = data;
+  wakeup_do_kick(loop);
+}
+
 void
-birdloop_start(struct birdloop *loop)
+birdloop_stop(struct birdloop *loop, void (*stopped)(void *data), void *data)
 {
-  int rv = pthread_create(&loop->thread, NULL, birdloop_main, loop);
-  if (rv)
-    die("pthread_create(): %M", rv);
+  DG_LOCK(loop->time.domain);
+  birdloop_do_stop(loop, stopped, data);
+  DG_UNLOCK(loop->time.domain);
 }
 
 void
-birdloop_stop(struct birdloop *loop)
+birdloop_stop_self(struct birdloop *loop, void (*stopped)(void *data), void *data)
 {
-  pthread_mutex_lock(&loop->mutex);
-  loop->stop_called = 1;
-  wakeup_do_kick(loop);
-  pthread_mutex_unlock(&loop->mutex);
+  ASSERT_DIE(loop == birdloop_current);
+  ASSERT_DIE(DG_IS_LOCKED(loop->time.domain));
 
-  int rv = pthread_join(loop->thread, NULL);
-  if (rv)
-    die("pthread_join(): %M", rv);
+  birdloop_do_stop(loop, stopped, data);
 }
 
 void
 birdloop_free(struct birdloop *loop)
 {
+  ASSERT_DIE(loop->links == 0);
+  domain_free(loop->time.domain);
   rfree(loop->pool);
 }
 
+static void
+birdloop_enter_locked(struct birdloop *loop)
+{
+  ASSERT_DIE(DG_IS_LOCKED(loop->time.domain));
+  ASSERT_DIE(!birdloop_inside(loop));
+
+  /* Store the old context */
+  loop->prev_loop = birdloop_current;
+
+  /* Put the new context */
+  birdloop_current = loop;
+}
 
 void
 birdloop_enter(struct birdloop *loop)
 {
-  /* TODO: these functions could save and restore old context */
-  pthread_mutex_lock(&loop->mutex);
-  birdloop_set_current(loop);
+  DG_LOCK(loop->time.domain);
+  return birdloop_enter_locked(loop);
+}
+
+static void
+birdloop_leave_locked(struct birdloop *loop)
+{
+  /* Check the current context */
+  ASSERT_DIE(birdloop_current == loop);
+
+  /* Restore the old context */
+  birdloop_current = loop->prev_loop;
 }
 
 void
 birdloop_leave(struct birdloop *loop)
 {
-  /* TODO: these functions could save and restore old context */
-  birdloop_set_current(NULL);
-  pthread_mutex_unlock(&loop->mutex);
+  birdloop_leave_locked(loop);
+  DG_UNLOCK(loop->time.domain);
 }
 
 void
 birdloop_mask_wakeups(struct birdloop *loop)
 {
-  pthread_mutex_lock(&loop->mutex);
-  loop->wakeup_masked = 1;
-  pthread_mutex_unlock(&loop->mutex);
+  ASSERT_DIE(birdloop_wakeup_masked == NULL);
+  birdloop_wakeup_masked = loop;
 }
 
 void
 birdloop_unmask_wakeups(struct birdloop *loop)
 {
-  pthread_mutex_lock(&loop->mutex);
-  if (loop->wakeup_masked == 2)
+  ASSERT_DIE(birdloop_wakeup_masked == loop);
+  birdloop_wakeup_masked = NULL;
+  if (birdloop_wakeup_masked_count)
     wakeup_do_kick(loop);
-  loop->wakeup_masked = 0;
-  pthread_mutex_unlock(&loop->mutex);
+
+  birdloop_wakeup_masked_count = 0;
 }
 
-static void *
+void
+birdloop_link(struct birdloop *loop)
+{
+  ASSERT_DIE(birdloop_inside(loop));
+  loop->links++;
+}
+
+void
+birdloop_unlink(struct birdloop *loop)
+{
+  ASSERT_DIE(birdloop_inside(loop));
+  loop->links--;
+}
+
+static void
 birdloop_main(void *arg)
 {
   struct birdloop *loop = arg;
   timer *t;
   int rv, timeout;
 
-  birdloop_set_current(loop);
+  btime loop_begin = current_time();
 
-  pthread_mutex_lock(&loop->mutex);
+  birdloop_enter(loop);
   while (1)
   {
-    events_fire(loop);
-    timers_fire(&loop->time);
-
-    times_update();
-    if (events_waiting(loop))
+    timers_fire(&loop->time, 0);
+    if (ev_run_list(&loop->event_list))
       timeout = 0;
     else if (t = timers_first(&loop->time))
       timeout = (tm_remains(t) TO_MS) + 1;
@@ -472,8 +489,11 @@ birdloop_main(void *arg)
     if (loop->poll_changed)
       sockets_prepare(loop);
 
-    loop->poll_active = 1;
-    pthread_mutex_unlock(&loop->mutex);
+    btime duration = current_time() - loop_begin;
+    if (duration > config->watchdog_warning)
+      log(L_WARN "I/O loop cycle took %d ms", (int) (duration TO_MS));
+
+    birdloop_leave(loop);
 
   try:
     rv = poll(loop->poll_fd.data, loop->poll_fd.used, timeout);
@@ -484,25 +504,32 @@ birdloop_main(void *arg)
       die("poll: %m");
     }
 
-    pthread_mutex_lock(&loop->mutex);
-    loop->poll_active = 0;
+    birdloop_enter(loop);
 
     if (loop->close_scheduled)
       sockets_close_fds(loop);
 
-    if (loop->stop_called)
+    if (loop->stopped)
       break;
 
+    loop_begin = current_time();
+
     if (rv)
       sockets_fire(loop);
 
-    timers_fire(&loop->time);
+    atomic_exchange_explicit(&loop->ping_sent, 0, memory_order_acq_rel);
   }
 
-  loop->stop_called = 0;
-  pthread_mutex_unlock(&loop->mutex);
+  /* Flush remaining events */
+  ASSERT_DIE(!ev_run_list(&loop->event_list));
+
+  /* No timers allowed */
+  ASSERT_DIE(timers_count(&loop->time) == 0);
+  ASSERT_DIE(EMPTY_LIST(loop->sock_list));
+  ASSERT_DIE(loop->sock_num == 0);
 
-  return NULL;
+  birdloop_leave(loop);
+  loop->stopped(loop->stop_data);
 }
 
 
diff --git a/sysdep/unix/io-loop.h b/sysdep/unix/io-loop.h
index d858b04e..4024b6c5 100644
--- a/sysdep/unix/io-loop.h
+++ b/sysdep/unix/io-loop.h
@@ -4,31 +4,32 @@
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
 
-#ifndef _BIRD_IO_LOOP_H_
-#define _BIRD_IO_LOOP_H_
+#ifndef _BIRD_SYSDEP_UNIX_IO_LOOP_H_
+#define _BIRD_SYSDEP_UNIX_IO_LOOP_H_
 
-#include "nest/bird.h"
-#include "lib/lists.h"
-#include "lib/resource.h"
-#include "lib/event.h"
-#include "lib/timer.h"
-#include "lib/socket.h"
+struct birdloop
+{
+  pool *pool;
 
+  struct timeloop time;
+  event_list event_list;
+  list sock_list;
+  uint sock_num;
 
-void ev2_schedule(event *e);
+  BUFFER(sock *) poll_sk;
+  BUFFER(struct pollfd) poll_fd;
+  u8 poll_changed;
+  u8 close_scheduled;
 
-void sk_start(sock *s);
-void sk_stop(sock *s);
+  _Atomic u32 ping_sent;
+  int wakeup_fds[2];
 
-struct birdloop *birdloop_new(void);
-void birdloop_start(struct birdloop *loop);
-void birdloop_stop(struct birdloop *loop);
-void birdloop_free(struct birdloop *loop);
+  uint links;
 
-void birdloop_enter(struct birdloop *loop);
-void birdloop_leave(struct birdloop *loop);
-void birdloop_mask_wakeups(struct birdloop *loop);
-void birdloop_unmask_wakeups(struct birdloop *loop);
+  void (*stopped)(void *data);
+  void *stop_data;
 
+  struct birdloop *prev_loop;
+};
 
-#endif /* _BIRD_IO_LOOP_H_ */
+#endif
diff --git a/sysdep/unix/io.c b/sysdep/unix/io.c
index 90bb5d64..c91f2856 100644
--- a/sysdep/unix/io.c
+++ b/sysdep/unix/io.c
@@ -43,6 +43,7 @@
 #include "conf/conf.h"
 
 #include "sysdep/unix/unix.h"
+#include "sysdep/unix/io-loop.h"
 #include CONFIG_INCLUDE_SYSIO_H
 
 /* Maximum number of calls of tx handler for one socket in one
@@ -800,18 +801,16 @@ sk_free(resource *r)
     sk_ssh_free(s);
 #endif
 
-  if (s->fd < 0)
+  if ((s->fd < 0) || (s->flags & SKF_THREAD))
     return;
 
-  /* FIXME: we should call sk_stop() for SKF_THREAD sockets */
-  if (!(s->flags & SKF_THREAD))
-  {
-    if (s == current_sock)
-      current_sock = sk_next(s);
-    if (s == stored_sock)
-      stored_sock = sk_next(s);
+  if (s == current_sock)
+    current_sock = sk_next(s);
+  if (s == stored_sock)
+    stored_sock = sk_next(s);
+
+  if (enlisted(&s->n))
     rem_node(&s->n);
-  }
 
   if (s->type != SK_SSH && s->type != SK_SSH_ACTIVE)
     close(s->fd);
@@ -1104,7 +1103,11 @@ sk_passive_connected(sock *s, int type)
     return 1;
   }
 
-  sk_insert(t);
+  if (s->flags & SKF_PASSIVE_THREAD)
+    t->flags |= SKF_THREAD;
+  else
+    sk_insert(t);
+
   sk_alloc_bufs(t);
   s->rx_hook(t, 0);
   return 1;
@@ -1508,6 +1511,36 @@ sk_open_unix(sock *s, char *name)
   return 0;
 }
 
+static void
+sk_reloop_hook(void *_vs)
+{
+  sock *s = _vs;
+  if (birdloop_inside(&main_birdloop))
+  {
+    s->flags &= ~SKF_THREAD;
+    sk_insert(s);
+  }
+  else
+  {
+    s->flags |= SKF_THREAD;
+    sk_start(s);
+  }
+}
+
+void
+sk_reloop(sock *s, struct birdloop *loop)
+{
+  if (enlisted(&s->n))
+    rem_node(&s->n);
+
+  s->reloop = (event) {
+    .hook = sk_reloop_hook,
+    .data = s,
+  };
+
+  ev_send_loop(loop, &s->reloop);
+}
+
 
 #define CMSG_RX_SPACE MAX(CMSG4_SPACE_PKTINFO+CMSG4_SPACE_TTL, \
 			  CMSG6_SPACE_PKTINFO+CMSG6_SPACE_TTL)
@@ -2143,8 +2176,9 @@ void
 io_init(void)
 {
   init_list(&sock_list);
-  init_list(&global_event_list);
-  init_list(&global_work_list);
+  ev_init_list(&global_event_list, &main_birdloop, "Global event list");
+  ev_init_list(&global_work_list, &main_birdloop, "Global work list");
+  ev_init_list(&main_birdloop.event_list, &main_birdloop, "Global fast event list");
   krt_io_init();
   // XXX init_times();
   // XXX update_times();
@@ -2158,14 +2192,7 @@ static int short_loops = 0;
 #define SHORT_LOOP_MAX 10
 #define WORK_EVENTS_MAX 10
 
-static int poll_reload_pipe[2];
-
-void
-io_loop_reload(void)
-{
-  char b;
-  write(poll_reload_pipe[1], &b, 1);
-}
+void pipe_drain(int fd);
 
 void
 io_loop(void)
@@ -2178,21 +2205,19 @@ io_loop(void)
   int fdmax = 256;
   struct pollfd *pfd = xmalloc(fdmax * sizeof(struct pollfd));
 
-  if (pipe(poll_reload_pipe) < 0)
-    die("pipe(poll_reload_pipe) failed: %m");
-
   watchdog_start1();
   for(;;)
     {
       times_update();
       events = ev_run_list(&global_event_list);
       events = ev_run_list_limited(&global_work_list, WORK_EVENTS_MAX) || events;
-      timers_fire(&main_timeloop);
+      events = ev_run_list(&main_birdloop.event_list) || events;
+      timers_fire(&main_birdloop.time, 1);
       io_close_event();
 
       // FIXME
       poll_tout = (events ? 0 : 3000); /* Time in milliseconds */
-      if (t = timers_first(&main_timeloop))
+      if (t = timers_first(&main_birdloop.time))
       {
 	times_update();
 	timeout = (tm_remains(t) TO_MS) + 1;
@@ -2200,7 +2225,7 @@ io_loop(void)
       }
 
       /* A hack to reload main io_loop() when something has changed asynchronously. */
-      pfd[0].fd = poll_reload_pipe[0];
+      pfd[0].fd = main_birdloop.wakeup_fds[0];
       pfd[0].events = POLLIN;
 
       nfds = 1;
@@ -2263,9 +2288,9 @@ io_loop(void)
 
       /* And finally enter poll() to find active sockets */
       watchdog_stop();
-      the_bird_unlock();
+      birdloop_leave(&main_birdloop);
       pout = poll(pfd, nfds, poll_tout);
-      the_bird_lock();
+      birdloop_enter(&main_birdloop);
       watchdog_start();
 
       if (pout < 0)
@@ -2279,8 +2304,8 @@ io_loop(void)
 	  if (pfd[0].revents & POLLIN)
 	  {
 	    /* IO loop reload requested */
-	    char b;
-	    read(poll_reload_pipe[0], &b, 1);
+	    pipe_drain(main_birdloop.wakeup_fds[0]);
+	    atomic_exchange_explicit(&main_birdloop.ping_sent, 0, memory_order_acq_rel);
 	    continue;
 	  }
 
diff --git a/sysdep/unix/main.c b/sysdep/unix/main.c
index d35424ff..5da27cb6 100644
--- a/sysdep/unix/main.c
+++ b/sysdep/unix/main.c
@@ -908,10 +908,12 @@ main(int argc, char **argv)
   parse_args(argc, argv);
   log_switch(1, NULL, NULL);
 
+  the_bird_lock();
+
   random_init();
   net_init();
   resource_init();
-  timer_init();
+  birdloop_init();
   olock_init();
   io_init();
   rt_init();
@@ -961,7 +963,6 @@ main(int argc, char **argv)
       dup2(0, 2);
     }
 
-  the_bird_lock();
 
   main_thread_init();
 
diff --git a/sysdep/unix/unix.h b/sysdep/unix/unix.h
index 313c97c3..ad85d1ea 100644
--- a/sysdep/unix/unix.h
+++ b/sysdep/unix/unix.h
@@ -106,7 +106,6 @@ extern volatile sig_atomic_t async_shutdown_flag;
 
 void io_init(void);
 void io_loop(void);
-void io_loop_reload(void);
 void io_log_dump(void);
 int sk_open_unix(struct birdsock *s, char *name);
 struct rfile *rf_open(struct pool *, const char *name, const char *mode);