Merge branch 'upstream-libuv' into import-libuv

* upstream-libuv:
  libuv 2016-08-30 (897738b1)

1 files changed, 1638 insertions, 0 deletions

diff --git a/Utilities/cmlibuv/src/unix/stream.c b/Utilities/cmlibuv/src/unix/stream.c
new file mode 100644
index 0000000..d20d0bc
--- /dev/null
+++ b/Utilities/cmlibuv/src/unix/stream.c
@@ -0,0 +1,1638 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "internal.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <errno.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <sys/un.h>
+#include <unistd.h>
+#include <limits.h> /* IOV_MAX */
+
+#if defined(__APPLE__)
+# include <sys/event.h>
+# include <sys/time.h>
+# include <sys/select.h>
+
+/* Forward declaration */
+typedef struct uv__stream_select_s uv__stream_select_t;
+
+struct uv__stream_select_s {
+  uv_stream_t* stream;
+  uv_thread_t thread;
+  uv_sem_t close_sem;
+  uv_sem_t async_sem;
+  uv_async_t async;
+  int events;
+  int fake_fd;
+  int int_fd;
+  int fd;
+  fd_set* sread;
+  size_t sread_sz;
+  fd_set* swrite;
+  size_t swrite_sz;
+};
+#endif /* defined(__APPLE__) */
+
+static void uv__stream_connect(uv_stream_t*);
+static void uv__write(uv_stream_t* stream);
+static void uv__read(uv_stream_t* stream);
+static void uv__stream_io(uv_loop_t* loop, uv__io_t* w, unsigned int events);
+static void uv__write_callbacks(uv_stream_t* stream);
+static size_t uv__write_req_size(uv_write_t* req);
+
+
+void uv__stream_init(uv_loop_t* loop,
+                     uv_stream_t* stream,
+                     uv_handle_type type) {
+  int err;
+
+  uv__handle_init(loop, (uv_handle_t*)stream, type);
+  stream->read_cb = NULL;
+  stream->alloc_cb = NULL;
+  stream->close_cb = NULL;
+  stream->connection_cb = NULL;
+  stream->connect_req = NULL;
+  stream->shutdown_req = NULL;
+  stream->accepted_fd = -1;
+  stream->queued_fds = NULL;
+  stream->delayed_error = 0;
+  QUEUE_INIT(&stream->write_queue);
+  QUEUE_INIT(&stream->write_completed_queue);
+  stream->write_queue_size = 0;
+
+  if (loop->emfile_fd == -1) {
+    err = uv__open_cloexec("/dev/null", O_RDONLY);
+    if (err < 0)
+        /* In the rare case that "/dev/null" isn't mounted open "/"
+         * instead.
+         */
+        err = uv__open_cloexec("/", O_RDONLY);
+    if (err >= 0)
+      loop->emfile_fd = err;
+  }
+
+#if defined(__APPLE__)
+  stream->select = NULL;
+#endif /* defined(__APPLE_) */
+
+  uv__io_init(&stream->io_watcher, uv__stream_io, -1);
+}
+
+
+static void uv__stream_osx_interrupt_select(uv_stream_t* stream) {
+#if defined(__APPLE__)
+  /* Notify select() thread about state change */
+  uv__stream_select_t* s;
+  int r;
+
+  s = stream->select;
+  if (s == NULL)
+    return;
+
+  /* Interrupt select() loop
+   * NOTE: fake_fd and int_fd are socketpair(), thus writing to one will
+   * emit read event on other side
+   */
+  do
+    r = write(s->fake_fd, "x", 1);
+  while (r == -1 && errno == EINTR);
+
+  assert(r == 1);
+#else  /* !defined(__APPLE__) */
+  /* No-op on any other platform */
+#endif  /* !defined(__APPLE__) */
+}
+
+
+#if defined(__APPLE__)
+static void uv__stream_osx_select(void* arg) {
+  uv_stream_t* stream;
+  uv__stream_select_t* s;
+  char buf[1024];
+  int events;
+  int fd;
+  int r;
+  int max_fd;
+
+  stream = arg;
+  s = stream->select;
+  fd = s->fd;
+
+  if (fd > s->int_fd)
+    max_fd = fd;
+  else
+    max_fd = s->int_fd;
+
+  while (1) {
+    /* Terminate on semaphore */
+    if (uv_sem_trywait(&s->close_sem) == 0)
+      break;
+
+    /* Watch fd using select(2) */
+    memset(s->sread, 0, s->sread_sz);
+    memset(s->swrite, 0, s->swrite_sz);
+
+    if (uv__io_active(&stream->io_watcher, POLLIN))
+      FD_SET(fd, s->sread);
+    if (uv__io_active(&stream->io_watcher, POLLOUT))
+      FD_SET(fd, s->swrite);
+    FD_SET(s->int_fd, s->sread);
+
+    /* Wait indefinitely for fd events */
+    r = select(max_fd + 1, s->sread, s->swrite, NULL, NULL);
+    if (r == -1) {
+      if (errno == EINTR)
+        continue;
+
+      /* XXX: Possible?! */
+      abort();
+    }
+
+    /* Ignore timeouts */
+    if (r == 0)
+      continue;
+
+    /* Empty socketpair's buffer in case of interruption */
+    if (FD_ISSET(s->int_fd, s->sread))
+      while (1) {
+        r = read(s->int_fd, buf, sizeof(buf));
+
+        if (r == sizeof(buf))
+          continue;
+
+        if (r != -1)
+          break;
+
+        if (errno == EAGAIN || errno == EWOULDBLOCK)
+          break;
+
+        if (errno == EINTR)
+          continue;
+
+        abort();
+      }
+
+    /* Handle events */
+    events = 0;
+    if (FD_ISSET(fd, s->sread))
+      events |= POLLIN;
+    if (FD_ISSET(fd, s->swrite))
+      events |= POLLOUT;
+
+    assert(events != 0 || FD_ISSET(s->int_fd, s->sread));
+    if (events != 0) {
+      ACCESS_ONCE(int, s->events) = events;
+
+      uv_async_send(&s->async);
+      uv_sem_wait(&s->async_sem);
+
+      /* Should be processed at this stage */
+      assert((s->events == 0) || (stream->flags & UV_CLOSING));
+    }
+  }
+}
+
+
+static void uv__stream_osx_select_cb(uv_async_t* handle) {
+  uv__stream_select_t* s;
+  uv_stream_t* stream;
+  int events;
+
+  s = container_of(handle, uv__stream_select_t, async);
+  stream = s->stream;
+
+  /* Get and reset stream's events */
+  events = s->events;
+  ACCESS_ONCE(int, s->events) = 0;
+
+  assert(events != 0);
+  assert(events == (events & (POLLIN | POLLOUT)));
+
+  /* Invoke callback on event-loop */
+  if ((events & POLLIN) && uv__io_active(&stream->io_watcher, POLLIN))
+    uv__stream_io(stream->loop, &stream->io_watcher, POLLIN);
+
+  if ((events & POLLOUT) && uv__io_active(&stream->io_watcher, POLLOUT))
+    uv__stream_io(stream->loop, &stream->io_watcher, POLLOUT);
+
+  if (stream->flags & UV_CLOSING)
+    return;
+
+  /* NOTE: It is important to do it here, otherwise `select()` might be called
+   * before the actual `uv__read()`, leading to the blocking syscall
+   */
+  uv_sem_post(&s->async_sem);
+}
+
+
+static void uv__stream_osx_cb_close(uv_handle_t* async) {
+  uv__stream_select_t* s;
+
+  s = container_of(async, uv__stream_select_t, async);
+  uv__free(s);
+}
+
+
+int uv__stream_try_select(uv_stream_t* stream, int* fd) {
+  /*
+   * kqueue doesn't work with some files from /dev mount on osx.
+   * select(2) in separate thread for those fds
+   */
+
+  struct kevent filter[1];
+  struct kevent events[1];
+  struct timespec timeout;
+  uv__stream_select_t* s;
+  int fds[2];
+  int err;
+  int ret;
+  int kq;
+  int old_fd;
+  int max_fd;
+  size_t sread_sz;
+  size_t swrite_sz;
+
+  kq = kqueue();
+  if (kq == -1) {
+    perror("(libuv) kqueue()");
+    return -errno;
+  }
+
+  EV_SET(&filter[0], *fd, EVFILT_READ, EV_ADD | EV_ENABLE, 0, 0, 0);
+
+  /* Use small timeout, because we only want to capture EINVALs */
+  timeout.tv_sec = 0;
+  timeout.tv_nsec = 1;
+
+  do
+    ret = kevent(kq, filter, 1, events, 1, &timeout);
+  while (ret == -1 && errno == EINTR);
+
+  uv__close(kq);
+
+  if (ret == -1)
+    return -errno;
+
+  if (ret == 0 || (events[0].flags & EV_ERROR) == 0 || events[0].data != EINVAL)
+    return 0;
+
+  /* At this point we definitely know that this fd won't work with kqueue */
+
+  /*
+   * Create fds for io watcher and to interrupt the select() loop.
+   * NOTE: do it ahead of malloc below to allocate enough space for fd_sets
+   */
+  if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds))
+    return -errno;
+
+  max_fd = *fd;
+  if (fds[1] > max_fd)
+    max_fd = fds[1];
+
+  sread_sz = ROUND_UP(max_fd + 1, sizeof(uint32_t) * NBBY) / NBBY;
+  swrite_sz = sread_sz;
+
+  s = uv__malloc(sizeof(*s) + sread_sz + swrite_sz);
+  if (s == NULL) {
+    err = -ENOMEM;
+    goto failed_malloc;
+  }
+
+  s->events = 0;
+  s->fd = *fd;
+  s->sread = (fd_set*) ((char*) s + sizeof(*s));
+  s->sread_sz = sread_sz;
+  s->swrite = (fd_set*) ((char*) s->sread + sread_sz);
+  s->swrite_sz = swrite_sz;
+
+  err = uv_async_init(stream->loop, &s->async, uv__stream_osx_select_cb);
+  if (err)
+    goto failed_async_init;
+
+  s->async.flags |= UV__HANDLE_INTERNAL;
+  uv__handle_unref(&s->async);
+
+  err = uv_sem_init(&s->close_sem, 0);
+  if (err != 0)
+    goto failed_close_sem_init;
+
+  err = uv_sem_init(&s->async_sem, 0);
+  if (err != 0)
+    goto failed_async_sem_init;
+
+  s->fake_fd = fds[0];
+  s->int_fd = fds[1];
+
+  old_fd = *fd;
+  s->stream = stream;
+  stream->select = s;
+  *fd = s->fake_fd;
+
+  err = uv_thread_create(&s->thread, uv__stream_osx_select, stream);
+  if (err != 0)
+    goto failed_thread_create;
+
+  return 0;
+
+failed_thread_create:
+  s->stream = NULL;
+  stream->select = NULL;
+  *fd = old_fd;
+
+  uv_sem_destroy(&s->async_sem);
+
+failed_async_sem_init:
+  uv_sem_destroy(&s->close_sem);
+
+failed_close_sem_init:
+  uv__close(fds[0]);
+  uv__close(fds[1]);
+  uv_close((uv_handle_t*) &s->async, uv__stream_osx_cb_close);
+  return err;
+
+failed_async_init:
+  uv__free(s);
+
+failed_malloc:
+  uv__close(fds[0]);
+  uv__close(fds[1]);
+
+  return err;
+}
+#endif /* defined(__APPLE__) */
+
+
+int uv__stream_open(uv_stream_t* stream, int fd, int flags) {
+#if defined(__APPLE__)
+  int enable;
+#endif
+
+  if (!(stream->io_watcher.fd == -1 || stream->io_watcher.fd == fd))
+    return -EBUSY;
+
+  assert(fd >= 0);
+  stream->flags |= flags;
+
+  if (stream->type == UV_TCP) {
+    if ((stream->flags & UV_TCP_NODELAY) && uv__tcp_nodelay(fd, 1))
+      return -errno;
+
+    /* TODO Use delay the user passed in. */
+    if ((stream->flags & UV_TCP_KEEPALIVE) && uv__tcp_keepalive(fd, 1, 60))
+      return -errno;
+  }
+
+#if defined(__APPLE__)
+  enable = 1;
+  if (setsockopt(fd, SOL_SOCKET, SO_OOBINLINE, &enable, sizeof(enable)) &&
+      errno != ENOTSOCK &&
+      errno != EINVAL) {
+    return -errno;
+  }
+#endif
+
+  stream->io_watcher.fd = fd;
+
+  return 0;
+}
+
+
+void uv__stream_flush_write_queue(uv_stream_t* stream, int error) {
+  uv_write_t* req;
+  QUEUE* q;
+  while (!QUEUE_EMPTY(&stream->write_queue)) {
+    q = QUEUE_HEAD(&stream->write_queue);
+    QUEUE_REMOVE(q);
+
+    req = QUEUE_DATA(q, uv_write_t, queue);
+    req->error = error;
+
+    QUEUE_INSERT_TAIL(&stream->write_completed_queue, &req->queue);
+  }
+}
+
+
+void uv__stream_destroy(uv_stream_t* stream) {
+  assert(!uv__io_active(&stream->io_watcher, POLLIN | POLLOUT));
+  assert(stream->flags & UV_CLOSED);
+
+  if (stream->connect_req) {
+    uv__req_unregister(stream->loop, stream->connect_req);
+    stream->connect_req->cb(stream->connect_req, -ECANCELED);
+    stream->connect_req = NULL;
+  }
+
+  uv__stream_flush_write_queue(stream, -ECANCELED);
+  uv__write_callbacks(stream);
+
+  if (stream->shutdown_req) {
+    /* The ECANCELED error code is a lie, the shutdown(2) syscall is a
+     * fait accompli at this point. Maybe we should revisit this in v0.11.
+     * A possible reason for leaving it unchanged is that it informs the
+     * callee that the handle has been destroyed.
+     */
+    uv__req_unregister(stream->loop, stream->shutdown_req);
+    stream->shutdown_req->cb(stream->shutdown_req, -ECANCELED);
+    stream->shutdown_req = NULL;
+  }
+
+  assert(stream->write_queue_size == 0);
+}
+
+
+/* Implements a best effort approach to mitigating accept() EMFILE errors.
+ * We have a spare file descriptor stashed away that we close to get below
+ * the EMFILE limit. Next, we accept all pending connections and close them
+ * immediately to signal the clients that we're overloaded - and we are, but
+ * we still keep on trucking.
+ *
+ * There is one caveat: it's not reliable in a multi-threaded environment.
+ * The file descriptor limit is per process. Our party trick fails if another
+ * thread opens a file or creates a socket in the time window between us
+ * calling close() and accept().
+ */
+static int uv__emfile_trick(uv_loop_t* loop, int accept_fd) {
+  int err;
+  int emfile_fd;
+
+  if (loop->emfile_fd == -1)
+    return -EMFILE;
+
+  uv__close(loop->emfile_fd);
+  loop->emfile_fd = -1;
+
+  do {
+    err = uv__accept(accept_fd);
+    if (err >= 0)
+      uv__close(err);
+  } while (err >= 0 || err == -EINTR);
+
+  emfile_fd = uv__open_cloexec("/", O_RDONLY);
+  if (emfile_fd >= 0)
+    loop->emfile_fd = emfile_fd;
+
+  return err;
+}
+
+
+#if defined(UV_HAVE_KQUEUE)
+# define UV_DEC_BACKLOG(w) w->rcount--;
+#else
+# define UV_DEC_BACKLOG(w) /* no-op */
+#endif /* defined(UV_HAVE_KQUEUE) */
+
+
+void uv__server_io(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
+  uv_stream_t* stream;
+  int err;
+
+  stream = container_of(w, uv_stream_t, io_watcher);
+  assert(events == POLLIN);
+  assert(stream->accepted_fd == -1);
+  assert(!(stream->flags & UV_CLOSING));
+
+  uv__io_start(stream->loop, &stream->io_watcher, POLLIN);
+
+  /* connection_cb can close the server socket while we're
+   * in the loop so check it on each iteration.
+   */
+  while (uv__stream_fd(stream) != -1) {
+    assert(stream->accepted_fd == -1);
+
+#if defined(UV_HAVE_KQUEUE)
+    if (w->rcount <= 0)
+      return;
+#endif /* defined(UV_HAVE_KQUEUE) */
+
+    err = uv__accept(uv__stream_fd(stream));
+    if (err < 0) {
+      if (err == -EAGAIN || err == -EWOULDBLOCK)
+        return;  /* Not an error. */
+
+      if (err == -ECONNABORTED)
+        continue;  /* Ignore. Nothing we can do about that. */
+
+      if (err == -EMFILE || err == -ENFILE) {
+        err = uv__emfile_trick(loop, uv__stream_fd(stream));
+        if (err == -EAGAIN || err == -EWOULDBLOCK)
+          break;
+      }
+
+      stream->connection_cb(stream, err);
+      continue;
+    }
+
+    UV_DEC_BACKLOG(w)
+    stream->accepted_fd = err;
+    stream->connection_cb(stream, 0);
+
+    if (stream->accepted_fd != -1) {
+      /* The user hasn't yet accepted called uv_accept() */
+      uv__io_stop(loop, &stream->io_watcher, POLLIN);
+      return;
+    }
+
+    if (stream->type == UV_TCP && (stream->flags & UV_TCP_SINGLE_ACCEPT)) {
+      /* Give other processes a chance to accept connections. */
+      struct timespec timeout = { 0, 1 };
+      nanosleep(&timeout, NULL);
+    }
+  }
+}
+
+
+#undef UV_DEC_BACKLOG
+
+
+int uv_accept(uv_stream_t* server, uv_stream_t* client) {
+  int err;
+
+  assert(server->loop == client->loop);
+
+  if (server->accepted_fd == -1)
+    return -EAGAIN;
+
+  switch (client->type) {
+    case UV_NAMED_PIPE:
+    case UV_TCP:
+      err = uv__stream_open(client,
+                            server->accepted_fd,
+                            UV_STREAM_READABLE | UV_STREAM_WRITABLE);
+      if (err) {
+        /* TODO handle error */
+        uv__close(server->accepted_fd);
+        goto done;
+      }
+      break;
+
+    case UV_UDP:
+      err = uv_udp_open((uv_udp_t*) client, server->accepted_fd);
+      if (err) {
+        uv__close(server->accepted_fd);
+        goto done;
+      }
+      break;
+
+    default:
+      return -EINVAL;
+  }
+
+  client->flags |= UV_HANDLE_BOUND;
+
+done:
+  /* Process queued fds */
+  if (server->queued_fds != NULL) {
+    uv__stream_queued_fds_t* queued_fds;
+
+    queued_fds = server->queued_fds;
+
+    /* Read first */
+    server->accepted_fd = queued_fds->fds[0];
+
+    /* All read, free */
+    assert(queued_fds->offset > 0);
+    if (--queued_fds->offset == 0) {
+      uv__free(queued_fds);
+      server->queued_fds = NULL;
+    } else {
+      /* Shift rest */
+      memmove(queued_fds->fds,
+              queued_fds->fds + 1,
+              queued_fds->offset * sizeof(*queued_fds->fds));
+    }
+  } else {
+    server->accepted_fd = -1;
+    if (err == 0)
+      uv__io_start(server->loop, &server->io_watcher, POLLIN);
+  }
+  return err;
+}
+
+
+int uv_listen(uv_stream_t* stream, int backlog, uv_connection_cb cb) {
+  int err;
+
+  switch (stream->type) {
+  case UV_TCP:
+    err = uv_tcp_listen((uv_tcp_t*)stream, backlog, cb);
+    break;
+
+  case UV_NAMED_PIPE:
+    err = uv_pipe_listen((uv_pipe_t*)stream, backlog, cb);
+    break;
+
+  default:
+    err = -EINVAL;
+  }
+
+  if (err == 0)
+    uv__handle_start(stream);
+
+  return err;
+}
+
+
+static void uv__drain(uv_stream_t* stream) {
+  uv_shutdown_t* req;
+  int err;
+
+  assert(QUEUE_EMPTY(&stream->write_queue));
+  uv__io_stop(stream->loop, &stream->io_watcher, POLLOUT);
+  uv__stream_osx_interrupt_select(stream);
+
+  /* Shutdown? */
+  if ((stream->flags & UV_STREAM_SHUTTING) &&
+      !(stream->flags & UV_CLOSING) &&
+      !(stream->flags & UV_STREAM_SHUT)) {
+    assert(stream->shutdown_req);
+
+    req = stream->shutdown_req;
+    stream->shutdown_req = NULL;
+    stream->flags &= ~UV_STREAM_SHUTTING;
+    uv__req_unregister(stream->loop, req);
+
+    err = 0;
+    if (shutdown(uv__stream_fd(stream), SHUT_WR))
+      err = -errno;
+
+    if (err == 0)
+      stream->flags |= UV_STREAM_SHUT;
+
+    if (req->cb != NULL)
+      req->cb(req, err);
+  }
+}
+
+
+static size_t uv__write_req_size(uv_write_t* req) {
+  size_t size;
+
+  assert(req->bufs != NULL);
+  size = uv__count_bufs(req->bufs + req->write_index,
+                        req->nbufs - req->write_index);
+  assert(req->handle->write_queue_size >= size);
+
+  return size;
+}
+
+
+static void uv__write_req_finish(uv_write_t* req) {
+  uv_stream_t* stream = req->handle;
+
+  /* Pop the req off tcp->write_queue. */
+  QUEUE_REMOVE(&req->queue);
+
+  /* Only free when there was no error. On error, we touch up write_queue_size
+   * right before making the callback. The reason we don't do that right away
+   * is that a write_queue_size > 0 is our only way to signal to the user that
+   * they should stop writing - which they should if we got an error. Something
+   * to revisit in future revisions of the libuv API.
+   */
+  if (req->error == 0) {
+    if (req->bufs != req->bufsml)
+      uv__free(req->bufs);
+    req->bufs = NULL;
+  }
+
+  /* Add it to the write_completed_queue where it will have its
+   * callback called in the near future.
+   */
+  QUEUE_INSERT_TAIL(&stream->write_completed_queue, &req->queue);
+  uv__io_feed(stream->loop, &stream->io_watcher);
+}
+
+
+static int uv__handle_fd(uv_handle_t* handle) {
+  switch (handle->type) {
+    case UV_NAMED_PIPE:
+    case UV_TCP:
+      return ((uv_stream_t*) handle)->io_watcher.fd;
+
+    case UV_UDP:
+      return ((uv_udp_t*) handle)->io_watcher.fd;
+
+    default:
+      return -1;
+  }
+}
+
+static void uv__write(uv_stream_t* stream) {
+  struct iovec* iov;
+  QUEUE* q;
+  uv_write_t* req;
+  int iovmax;
+  int iovcnt;
+  ssize_t n;
+
+start:
+
+  assert(uv__stream_fd(stream) >= 0);
+
+  if (QUEUE_EMPTY(&stream->write_queue))
+    return;
+
+  q = QUEUE_HEAD(&stream->write_queue);
+  req = QUEUE_DATA(q, uv_write_t, queue);
+  assert(req->handle == stream);
+
+  /*
+   * Cast to iovec. We had to have our own uv_buf_t instead of iovec
+   * because Windows's WSABUF is not an iovec.
+   */
+  assert(sizeof(uv_buf_t) == sizeof(struct iovec));
+  iov = (struct iovec*) &(req->bufs[req->write_index]);
+  iovcnt = req->nbufs - req->write_index;
+
+  iovmax = uv__getiovmax();
+
+  /* Limit iov count to avoid EINVALs from writev() */
+  if (iovcnt > iovmax)
+    iovcnt = iovmax;
+
+  /*
+   * Now do the actual writev. Note that we've been updating the pointers
+   * inside the iov each time we write. So there is no need to offset it.
+   */
+
+  if (req->send_handle) {
+    struct msghdr msg;
+    struct cmsghdr *cmsg;
+    int fd_to_send = uv__handle_fd((uv_handle_t*) req->send_handle);
+    char scratch[64] = {0};
+
+    assert(fd_to_send >= 0);
+
+    msg.msg_name = NULL;
+    msg.msg_namelen = 0;
+    msg.msg_iov = iov;
+    msg.msg_iovlen = iovcnt;
+    msg.msg_flags = 0;
+
+    msg.msg_control = (void*) scratch;
+    msg.msg_controllen = CMSG_SPACE(sizeof(fd_to_send));
+
+    cmsg = CMSG_FIRSTHDR(&msg);
+    cmsg->cmsg_level = SOL_SOCKET;
+    cmsg->cmsg_type = SCM_RIGHTS;
+    cmsg->cmsg_len = CMSG_LEN(sizeof(fd_to_send));
+
+    /* silence aliasing warning */
+    {
+      void* pv = CMSG_DATA(cmsg);
+      int* pi = pv;
+      *pi = fd_to_send;
+    }
+
+    do {
+      n = sendmsg(uv__stream_fd(stream), &msg, 0);
+    }
+#if defined(__APPLE__)
+    /*
+     * Due to a possible kernel bug at least in OS X 10.10 "Yosemite",
+     * EPROTOTYPE can be returned while trying to write to a socket that is
+     * shutting down. If we retry the write, we should get the expected EPIPE
+     * instead.
+     */
+    while (n == -1 && (errno == EINTR || errno == EPROTOTYPE));
+#else
+    while (n == -1 && errno == EINTR);
+#endif
+  } else {
+    do {
+      if (iovcnt == 1) {
+        n = write(uv__stream_fd(stream), iov[0].iov_base, iov[0].iov_len);
+      } else {
+        n = writev(uv__stream_fd(stream), iov, iovcnt);
+      }
+    }
+#if defined(__APPLE__)
+    /*
+     * Due to a possible kernel bug at least in OS X 10.10 "Yosemite",
+     * EPROTOTYPE can be returned while trying to write to a socket that is
+     * shutting down. If we retry the write, we should get the expected EPIPE
+     * instead.
+     */
+    while (n == -1 && (errno == EINTR || errno == EPROTOTYPE));
+#else
+    while (n == -1 && errno == EINTR);
+#endif
+  }
+
+  if (n < 0) {
+    if (errno != EAGAIN && errno != EWOULDBLOCK) {
+      /* Error */
+      req->error = -errno;
+      uv__write_req_finish(req);
+      uv__io_stop(stream->loop, &stream->io_watcher, POLLOUT);
+      if (!uv__io_active(&stream->io_watcher, POLLIN))
+        uv__handle_stop(stream);
+      uv__stream_osx_interrupt_select(stream);
+      return;
+    } else if (stream->flags & UV_STREAM_BLOCKING) {
+      /* If this is a blocking stream, try again. */
+      goto start;
+    }
+  } else {
+    /* Successful write */
+
+    while (n >= 0) {
+      uv_buf_t* buf = &(req->bufs[req->write_index]);
+      size_t len = buf->len;
+
+      assert(req->write_index < req->nbufs);
+
+      if ((size_t)n < len) {
+        buf->base += n;
+        buf->len -= n;
+        stream->write_queue_size -= n;
+        n = 0;
+
+        /* There is more to write. */
+        if (stream->flags & UV_STREAM_BLOCKING) {
+          /*
+           * If we're blocking then we should not be enabling the write
+           * watcher - instead we need to try again.
+           */
+          goto start;
+        } else {
+          /* Break loop and ensure the watcher is pending. */
+          break;
+        }
+
+      } else {
+        /* Finished writing the buf at index req->write_index. */
+        req->write_index++;
+
+        assert((size_t)n >= len);
+        n -= len;
+
+        assert(stream->write_queue_size >= len);
+        stream->write_queue_size -= len;
+
+        if (req->write_index == req->nbufs) {
+          /* Then we're done! */
+          assert(n == 0);
+          uv__write_req_finish(req);
+          /* TODO: start trying to write the next request. */
+          return;
+        }
+      }
+    }
+  }
+
+  /* Either we've counted n down to zero or we've got EAGAIN. */
+  assert(n == 0 || n == -1);
+
+  /* Only non-blocking streams should use the write_watcher. */
+  assert(!(stream->flags & UV_STREAM_BLOCKING));
+
+  /* We're not done. */
+  uv__io_start(stream->loop, &stream->io_watcher, POLLOUT);
+
+  /* Notify select() thread about state change */
+  uv__stream_osx_interrupt_select(stream);
+}
+
+
+static void uv__write_callbacks(uv_stream_t* stream) {
+  uv_write_t* req;
+  QUEUE* q;
+
+  while (!QUEUE_EMPTY(&stream->write_completed_queue)) {
+    /* Pop a req off write_completed_queue. */
+    q = QUEUE_HEAD(&stream->write_completed_queue);
+    req = QUEUE_DATA(q, uv_write_t, queue);
+    QUEUE_REMOVE(q);
+    uv__req_unregister(stream->loop, req);
+
+    if (req->bufs != NULL) {
+      stream->write_queue_size -= uv__write_req_size(req);
+      if (req->bufs != req->bufsml)
+        uv__free(req->bufs);
+      req->bufs = NULL;
+    }
+
+    /* NOTE: call callback AFTER freeing the request data. */
+    if (req->cb)
+      req->cb(req, req->error);
+  }
+
+  assert(QUEUE_EMPTY(&stream->write_completed_queue));
+}
+
+
+uv_handle_type uv__handle_type(int fd) {
+  struct sockaddr_storage ss;
+  socklen_t sslen;
+  socklen_t len;
+  int type;
+
+  memset(&ss, 0, sizeof(ss));
+  sslen = sizeof(ss);
+
+  if (getsockname(fd, (struct sockaddr*)&ss, &sslen))
+    return UV_UNKNOWN_HANDLE;
+
+  len = sizeof type;
+
+  if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &type, &len))
+    return UV_UNKNOWN_HANDLE;
+
+  if (type == SOCK_STREAM) {
+#if defined(_AIX) || defined(__DragonFly__)
+    /* on AIX/DragonFly the getsockname call returns an empty sa structure
+     * for sockets of type AF_UNIX.  For all other types it will
+     * return a properly filled in structure.
+     */
+    if (sslen == 0)
+      return UV_NAMED_PIPE;
+#endif
+    switch (ss.ss_family) {
+      case AF_UNIX:
+        return UV_NAMED_PIPE;
+      case AF_INET:
+      case AF_INET6:
+        return UV_TCP;
+      }
+  }
+
+  if (type == SOCK_DGRAM &&
+      (ss.ss_family == AF_INET || ss.ss_family == AF_INET6))
+    return UV_UDP;
+
+  return UV_UNKNOWN_HANDLE;
+}
+
+
+static void uv__stream_eof(uv_stream_t* stream, const uv_buf_t* buf) {
+  stream->flags |= UV_STREAM_READ_EOF;
+  uv__io_stop(stream->loop, &stream->io_watcher, POLLIN);
+  if (!uv__io_active(&stream->io_watcher, POLLOUT))
+    uv__handle_stop(stream);
+  uv__stream_osx_interrupt_select(stream);
+  stream->read_cb(stream, UV_EOF, buf);
+  stream->flags &= ~UV_STREAM_READING;
+}
+
+
+static int uv__stream_queue_fd(uv_stream_t* stream, int fd) {
+  uv__stream_queued_fds_t* queued_fds;
+  unsigned int queue_size;
+
+  queued_fds = stream->queued_fds;
+  if (queued_fds == NULL) {
+    queue_size = 8;
+    queued_fds = uv__malloc((queue_size - 1) * sizeof(*queued_fds->fds) +
+                            sizeof(*queued_fds));
+    if (queued_fds == NULL)
+      return -ENOMEM;
+    queued_fds->size = queue_size;
+    queued_fds->offset = 0;
+    stream->queued_fds = queued_fds;
+
+    /* Grow */
+  } else if (queued_fds->size == queued_fds->offset) {
+    queue_size = queued_fds->size + 8;
+    queued_fds = uv__realloc(queued_fds,
+                             (queue_size - 1) * sizeof(*queued_fds->fds) +
+                              sizeof(*queued_fds));
+
+    /*
+     * Allocation failure, report back.
+     * NOTE: if it is fatal - sockets will be closed in uv__stream_close
+     */
+    if (queued_fds == NULL)
+      return -ENOMEM;
+    queued_fds->size = queue_size;
+    stream->queued_fds = queued_fds;
+  }
+
+  /* Put fd in a queue */
+  queued_fds->fds[queued_fds->offset++] = fd;
+
+  return 0;
+}
+
+
+#define UV__CMSG_FD_COUNT 64
+#define UV__CMSG_FD_SIZE (UV__CMSG_FD_COUNT * sizeof(int))
+
+
+static int uv__stream_recv_cmsg(uv_stream_t* stream, struct msghdr* msg) {
+  struct cmsghdr* cmsg;
+
+  for (cmsg = CMSG_FIRSTHDR(msg); cmsg != NULL; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+    char* start;
+    char* end;
+    int err;
+    void* pv;
+    int* pi;
+    unsigned int i;
+    unsigned int count;
+
+    if (cmsg->cmsg_type != SCM_RIGHTS) {
+      fprintf(stderr, "ignoring non-SCM_RIGHTS ancillary data: %d\n",
+          cmsg->cmsg_type);
+      continue;
+    }
+
+    /* silence aliasing warning */
+    pv = CMSG_DATA(cmsg);
+    pi = pv;
+
+    /* Count available fds */
+    start = (char*) cmsg;
+    end = (char*) cmsg + cmsg->cmsg_len;
+    count = 0;
+    while (start + CMSG_LEN(count * sizeof(*pi)) < end)
+      count++;
+    assert(start + CMSG_LEN(count * sizeof(*pi)) == end);
+
+    for (i = 0; i < count; i++) {
+      /* Already has accepted fd, queue now */
+      if (stream->accepted_fd != -1) {
+        err = uv__stream_queue_fd(stream, pi[i]);
+        if (err != 0) {
+          /* Close rest */
+          for (; i < count; i++)
+            uv__close(pi[i]);
+          return err;
+        }
+      } else {
+        stream->accepted_fd = pi[i];
+      }
+    }
+  }
+
+  return 0;
+}
+
+
+#ifdef __clang__
+# pragma clang diagnostic push
+# pragma clang diagnostic ignored "-Wgnu-folding-constant"
+#endif
+
+static void uv__read(uv_stream_t* stream) {
+  uv_buf_t buf;
+  ssize_t nread;
+  struct msghdr msg;
+  char cmsg_space[CMSG_SPACE(UV__CMSG_FD_SIZE)];
+  int count;
+  int err;
+  int is_ipc;
+
+  stream->flags &= ~UV_STREAM_READ_PARTIAL;
+
+  /* Prevent loop starvation when the data comes in as fast as (or faster than)
+   * we can read it. XXX Need to rearm fd if we switch to edge-triggered I/O.
+   */
+  count = 32;
+
+  is_ipc = stream->type == UV_NAMED_PIPE && ((uv_pipe_t*) stream)->ipc;
+
+  /* XXX: Maybe instead of having UV_STREAM_READING we just test if
+   * tcp->read_cb is NULL or not?
+   */
+  while (stream->read_cb
+      && (stream->flags & UV_STREAM_READING)
+      && (count-- > 0)) {
+    assert(stream->alloc_cb != NULL);
+
+    buf = uv_buf_init(NULL, 0);
+    stream->alloc_cb((uv_handle_t*)stream, 64 * 1024, &buf);
+    if (buf.base == NULL || buf.len == 0) {
+      /* User indicates it can't or won't handle the read. */
+      stream->read_cb(stream, UV_ENOBUFS, &buf);
+      return;
+    }
+
+    assert(buf.base != NULL);
+    assert(uv__stream_fd(stream) >= 0);
+
+    if (!is_ipc) {
+      do {
+        nread = read(uv__stream_fd(stream), buf.base, buf.len);
+      }
+      while (nread < 0 && errno == EINTR);
+    } else {
+      /* ipc uses recvmsg */
+      msg.msg_flags = 0;
+      msg.msg_iov = (struct iovec*) &buf;
+      msg.msg_iovlen = 1;
+      msg.msg_name = NULL;
+      msg.msg_namelen = 0;
+      /* Set up to receive a descriptor even if one isn't in the message */
+      msg.msg_controllen = sizeof(cmsg_space);
+      msg.msg_control = cmsg_space;
+
+      do {
+        nread = uv__recvmsg(uv__stream_fd(stream), &msg, 0);
+      }
+      while (nread < 0 && errno == EINTR);
+    }
+
+    if (nread < 0) {
+      /* Error */
+      if (errno == EAGAIN || errno == EWOULDBLOCK) {
+        /* Wait for the next one. */
+        if (stream->flags & UV_STREAM_READING) {
+          uv__io_start(stream->loop, &stream->io_watcher, POLLIN);
+          uv__stream_osx_interrupt_select(stream);
+        }
+        stream->read_cb(stream, 0, &buf);
+      } else {
+        /* Error. User should call uv_close(). */
+        stream->read_cb(stream, -errno, &buf);
+        if (stream->flags & UV_STREAM_READING) {
+          stream->flags &= ~UV_STREAM_READING;
+          uv__io_stop(stream->loop, &stream->io_watcher, POLLIN);
+          if (!uv__io_active(&stream->io_watcher, POLLOUT))
+            uv__handle_stop(stream);
+          uv__stream_osx_interrupt_select(stream);
+        }
+      }
+      return;
+    } else if (nread == 0) {
+      uv__stream_eof(stream, &buf);
+      return;
+    } else {
+      /* Successful read */
+      ssize_t buflen = buf.len;
+
+      if (is_ipc) {
+        err = uv__stream_recv_cmsg(stream, &msg);
+        if (err != 0) {
+          stream->read_cb(stream, err, &buf);
+          return;
+        }
+      }
+      stream->read_cb(stream, nread, &buf);
+
+      /* Return if we didn't fill the buffer, there is no more data to read. */
+      if (nread < buflen) {
+        stream->flags |= UV_STREAM_READ_PARTIAL;
+        return;
+      }
+    }
+  }
+}
+
+
+#ifdef __clang__
+# pragma clang diagnostic pop
+#endif
+
+#undef UV__CMSG_FD_COUNT
+#undef UV__CMSG_FD_SIZE
+
+
+int uv_shutdown(uv_shutdown_t* req, uv_stream_t* stream, uv_shutdown_cb cb) {
+  assert((stream->type == UV_TCP || stream->type == UV_NAMED_PIPE) &&
+         "uv_shutdown (unix) only supports uv_handle_t right now");
+
+  if (!(stream->flags & UV_STREAM_WRITABLE) ||
+      stream->flags & UV_STREAM_SHUT ||
+      stream->flags & UV_STREAM_SHUTTING ||
+      stream->flags & UV_CLOSED ||
+      stream->flags & UV_CLOSING) {
+    return -ENOTCONN;
+  }
+
+  assert(uv__stream_fd(stream) >= 0);
+
+  /* Initialize request */
+  uv__req_init(stream->loop, req, UV_SHUTDOWN);
+  req->handle = stream;
+  req->cb = cb;
+  stream->shutdown_req = req;
+  stream->flags |= UV_STREAM_SHUTTING;
+
+  uv__io_start(stream->loop, &stream->io_watcher, POLLOUT);
+  uv__stream_osx_interrupt_select(stream);
+
+  return 0;
+}
+
+
+static void uv__stream_io(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
+  uv_stream_t* stream;
+
+  stream = container_of(w, uv_stream_t, io_watcher);
+
+  assert(stream->type == UV_TCP ||
+         stream->type == UV_NAMED_PIPE ||
+         stream->type == UV_TTY);
+  assert(!(stream->flags & UV_CLOSING));
+
+  if (stream->connect_req) {
+    uv__stream_connect(stream);
+    return;
+  }
+
+  assert(uv__stream_fd(stream) >= 0);
+
+  /* Ignore POLLHUP here. Even it it's set, there may still be data to read. */
+  if (events & (POLLIN | POLLERR | POLLHUP))
+    uv__read(stream);
+
+  if (uv__stream_fd(stream) == -1)
+    return;  /* read_cb closed stream. */
+
+  /* Short-circuit iff POLLHUP is set, the user is still interested in read
+   * events and uv__read() reported a partial read but not EOF. If the EOF
+   * flag is set, uv__read() called read_cb with err=UV_EOF and we don't
+   * have to do anything. If the partial read flag is not set, we can't
+   * report the EOF yet because there is still data to read.
+   */
+  if ((events & POLLHUP) &&
+      (stream->flags & UV_STREAM_READING) &&
+      (stream->flags & UV_STREAM_READ_PARTIAL) &&
+      !(stream->flags & UV_STREAM_READ_EOF)) {
+    uv_buf_t buf = { NULL, 0 };
+    uv__stream_eof(stream, &buf);
+  }
+
+  if (uv__stream_fd(stream) == -1)
+    return;  /* read_cb closed stream. */
+
+  if (events & (POLLOUT | POLLERR | POLLHUP)) {
+    uv__write(stream);
+    uv__write_callbacks(stream);
+
+    /* Write queue drained. */
+    if (QUEUE_EMPTY(&stream->write_queue))
+      uv__drain(stream);
+  }
+}
+
+
+/**
+ * We get called here from directly following a call to connect(2).
+ * In order to determine if we've errored out or succeeded must call
+ * getsockopt.
+ */
+static void uv__stream_connect(uv_stream_t* stream) {
+  int error;
+  uv_connect_t* req = stream->connect_req;
+  socklen_t errorsize = sizeof(int);
+
+  assert(stream->type == UV_TCP || stream->type == UV_NAMED_PIPE);
+  assert(req);
+
+  if (stream->delayed_error) {
+    /* To smooth over the differences between unixes errors that
+     * were reported synchronously on the first connect can be delayed
+     * until the next tick--which is now.
+     */
+    error = stream->delayed_error;
+    stream->delayed_error = 0;
+  } else {
+    /* Normal situation: we need to get the socket error from the kernel. */
+    assert(uv__stream_fd(stream) >= 0);
+    getsockopt(uv__stream_fd(stream),
+               SOL_SOCKET,
+               SO_ERROR,
+               &error,
+               &errorsize);
+    error = -error;
+  }
+
+  if (error == -EINPROGRESS)
+    return;
+
+  stream->connect_req = NULL;
+  uv__req_unregister(stream->loop, req);
+
+  if (error < 0 || QUEUE_EMPTY(&stream->write_queue)) {
+    uv__io_stop(stream->loop, &stream->io_watcher, POLLOUT);
+  }
+
+  if (req->cb)
+    req->cb(req, error);
+
+  if (uv__stream_fd(stream) == -1)
+    return;
+
+  if (error < 0) {
+    uv__stream_flush_write_queue(stream, -ECANCELED);
+    uv__write_callbacks(stream);
+  }
+}
+
+
+int uv_write2(uv_write_t* req,
+              uv_stream_t* stream,
+              const uv_buf_t bufs[],
+              unsigned int nbufs,
+              uv_stream_t* send_handle,
+              uv_write_cb cb) {
+  int empty_queue;
+
+  assert(nbufs > 0);
+  assert((stream->type == UV_TCP ||
+          stream->type == UV_NAMED_PIPE ||
+          stream->type == UV_TTY) &&
+         "uv_write (unix) does not yet support other types of streams");
+
+  if (uv__stream_fd(stream) < 0)
+    return -EBADF;
+
+  if (send_handle) {
+    if (stream->type != UV_NAMED_PIPE || !((uv_pipe_t*)stream)->ipc)
+      return -EINVAL;
+
+    /* XXX We abuse uv_write2() to send over UDP handles to child processes.
+     * Don't call uv__stream_fd() on those handles, it's a macro that on OS X
+     * evaluates to a function that operates on a uv_stream_t with a couple of
+     * OS X specific fields. On other Unices it does (handle)->io_watcher.fd,
+     * which works but only by accident.
+     */
+    if (uv__handle_fd((uv_handle_t*) send_handle) < 0)
+      return -EBADF;
+  }
+
+  /* It's legal for write_queue_size > 0 even when the write_queue is empty;
+   * it means there are error-state requests in the write_completed_queue that
+   * will touch up write_queue_size later, see also uv__write_req_finish().
+   * We could check that write_queue is empty instead but that implies making
+   * a write() syscall when we know that the handle is in error mode.
+   */
+  empty_queue = (stream->write_queue_size == 0);
+
+  /* Initialize the req */
+  uv__req_init(stream->loop, req, UV_WRITE);
+  req->cb = cb;
+  req->handle = stream;
+  req->error = 0;
+  req->send_handle = send_handle;
+  QUEUE_INIT(&req->queue);
+
+  req->bufs = req->bufsml;
+  if (nbufs > ARRAY_SIZE(req->bufsml))
+    req->bufs = uv__malloc(nbufs * sizeof(bufs[0]));
+
+  if (req->bufs == NULL)
+    return -ENOMEM;
+
+  memcpy(req->bufs, bufs, nbufs * sizeof(bufs[0]));
+  req->nbufs = nbufs;
+  req->write_index = 0;
+  stream->write_queue_size += uv__count_bufs(bufs, nbufs);
+
+  /* Append the request to write_queue. */
+  QUEUE_INSERT_TAIL(&stream->write_queue, &req->queue);
+
+  /* If the queue was empty when this function began, we should attempt to
+   * do the write immediately. Otherwise start the write_watcher and wait
+   * for the fd to become writable.
+   */
+  if (stream->connect_req) {
+    /* Still connecting, do nothing. */
+  }
+  else if (empty_queue) {
+    uv__write(stream);
+  }
+  else {
+    /*
+     * blocking streams should never have anything in the queue.
+     * if this assert fires then somehow the blocking stream isn't being
+     * sufficiently flushed in uv__write.
+     */
+    assert(!(stream->flags & UV_STREAM_BLOCKING));
+    uv__io_start(stream->loop, &stream->io_watcher, POLLOUT);
+    uv__stream_osx_interrupt_select(stream);
+  }
+
+  return 0;
+}
+
+
+/* The buffers to be written must remain valid until the callback is called.
+ * This is not required for the uv_buf_t array.
+ */
+int uv_write(uv_write_t* req,
+             uv_stream_t* handle,
+             const uv_buf_t bufs[],
+             unsigned int nbufs,
+             uv_write_cb cb) {
+  return uv_write2(req, handle, bufs, nbufs, NULL, cb);
+}
+
+
+void uv_try_write_cb(uv_write_t* req, int status) {
+  /* Should not be called */
+  abort();
+}
+
+
+int uv_try_write(uv_stream_t* stream,
+                 const uv_buf_t bufs[],
+                 unsigned int nbufs) {
+  int r;
+  int has_pollout;
+  size_t written;
+  size_t req_size;
+  uv_write_t req;
+
+  /* Connecting or already writing some data */
+  if (stream->connect_req != NULL || stream->write_queue_size != 0)
+    return -EAGAIN;
+
+  has_pollout = uv__io_active(&stream->io_watcher, POLLOUT);
+
+  r = uv_write(&req, stream, bufs, nbufs, uv_try_write_cb);
+  if (r != 0)
+    return r;
+
+  /* Remove not written bytes from write queue size */
+  written = uv__count_bufs(bufs, nbufs);
+  if (req.bufs != NULL)
+    req_size = uv__write_req_size(&req);
+  else
+    req_size = 0;
+  written -= req_size;
+  stream->write_queue_size -= req_size;
+
+  /* Unqueue request, regardless of immediateness */
+  QUEUE_REMOVE(&req.queue);
+  uv__req_unregister(stream->loop, &req);
+  if (req.bufs != req.bufsml)
+    uv__free(req.bufs);
+  req.bufs = NULL;
+
+  /* Do not poll for writable, if we wasn't before calling this */
+  if (!has_pollout) {
+    uv__io_stop(stream->loop, &stream->io_watcher, POLLOUT);
+    uv__stream_osx_interrupt_select(stream);
+  }
+
+  if (written == 0 && req_size != 0)
+    return -EAGAIN;
+  else
+    return written;
+}
+
+
+int uv_read_start(uv_stream_t* stream,
+                  uv_alloc_cb alloc_cb,
+                  uv_read_cb read_cb) {
+  assert(stream->type == UV_TCP || stream->type == UV_NAMED_PIPE ||
+      stream->type == UV_TTY);
+
+  if (stream->flags & UV_CLOSING)
+    return -EINVAL;
+
+  /* The UV_STREAM_READING flag is irrelevant of the state of the tcp - it just
+   * expresses the desired state of the user.
+   */
+  stream->flags |= UV_STREAM_READING;
+
+  /* TODO: try to do the read inline? */
+  /* TODO: keep track of tcp state. If we've gotten a EOF then we should
+   * not start the IO watcher.
+   */
+  assert(uv__stream_fd(stream) >= 0);
+  assert(alloc_cb);
+
+  stream->read_cb = read_cb;
+  stream->alloc_cb = alloc_cb;
+
+  uv__io_start(stream->loop, &stream->io_watcher, POLLIN);
+  uv__handle_start(stream);
+  uv__stream_osx_interrupt_select(stream);
+
+  return 0;
+}
+
+
+int uv_read_stop(uv_stream_t* stream) {
+  if (!(stream->flags & UV_STREAM_READING))
+    return 0;
+
+  stream->flags &= ~UV_STREAM_READING;
+  uv__io_stop(stream->loop, &stream->io_watcher, POLLIN);
+  if (!uv__io_active(&stream->io_watcher, POLLOUT))
+    uv__handle_stop(stream);
+  uv__stream_osx_interrupt_select(stream);
+
+  stream->read_cb = NULL;
+  stream->alloc_cb = NULL;
+  return 0;
+}
+
+
+int uv_is_readable(const uv_stream_t* stream) {
+  return !!(stream->flags & UV_STREAM_READABLE);
+}
+
+
+int uv_is_writable(const uv_stream_t* stream) {
+  return !!(stream->flags & UV_STREAM_WRITABLE);
+}
+
+
+#if defined(__APPLE__)
+int uv___stream_fd(const uv_stream_t* handle) {
+  const uv__stream_select_t* s;
+
+  assert(handle->type == UV_TCP ||
+         handle->type == UV_TTY ||
+         handle->type == UV_NAMED_PIPE);
+
+  s = handle->select;
+  if (s != NULL)
+    return s->fd;
+
+  return handle->io_watcher.fd;
+}
+#endif /* defined(__APPLE__) */
+
+
+void uv__stream_close(uv_stream_t* handle) {
+  unsigned int i;
+  uv__stream_queued_fds_t* queued_fds;
+
+#if defined(__APPLE__)
+  /* Terminate select loop first */
+  if (handle->select != NULL) {
+    uv__stream_select_t* s;
+
+    s = handle->select;
+
+    uv_sem_post(&s->close_sem);
+    uv_sem_post(&s->async_sem);
+    uv__stream_osx_interrupt_select(handle);
+    uv_thread_join(&s->thread);
+    uv_sem_destroy(&s->close_sem);
+    uv_sem_destroy(&s->async_sem);
+    uv__close(s->fake_fd);
+    uv__close(s->int_fd);
+    uv_close((uv_handle_t*) &s->async, uv__stream_osx_cb_close);
+
+    handle->select = NULL;
+  }
+#endif /* defined(__APPLE__) */
+
+  uv__io_close(handle->loop, &handle->io_watcher);
+  uv_read_stop(handle);
+  uv__handle_stop(handle);
+
+  if (handle->io_watcher.fd != -1) {
+    /* Don't close stdio file descriptors.  Nothing good comes from it. */
+    if (handle->io_watcher.fd > STDERR_FILENO)
+      uv__close(handle->io_watcher.fd);
+    handle->io_watcher.fd = -1;
+  }
+
+  if (handle->accepted_fd != -1) {
+    uv__close(handle->accepted_fd);
+    handle->accepted_fd = -1;
+  }
+
+  /* Close all queued fds */
+  if (handle->queued_fds != NULL) {
+    queued_fds = handle->queued_fds;
+    for (i = 0; i < queued_fds->offset; i++)
+      uv__close(queued_fds->fds[i]);
+    uv__free(handle->queued_fds);
+    handle->queued_fds = NULL;
+  }
+
+  assert(!uv__io_active(&handle->io_watcher, POLLIN | POLLOUT));
+}
+
+
+int uv_stream_set_blocking(uv_stream_t* handle, int blocking) {
+  /* Don't need to check the file descriptor, uv__nonblock()
+   * will fail with EBADF if it's not valid.
+   */
+  return uv__nonblock(uv__stream_fd(handle), !blocking);
+}