text: /* 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 <stddef.h> /* NULL */
  #include <stdio.h> /* printf */
  #include <stdlib.h>
  #include <string.h> /* strerror */
  #include <errno.h>
  #include <assert.h>
  #include <unistd.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>  /* O_CLOEXEC */
  #include <sys/ioctl.h>
  #include <sys/socket.h>
  #include <sys/un.h>
  #include <netinet/in.h>
  #include <arpa/inet.h>
  #include <limits.h> /* INT_MAX, PATH_MAX, IOV_MAX */
  #include <sys/uio.h> /* writev */
  #include <sys/resource.h> /* getrusage */
  #include <pwd.h>
  #include <sys/utsname.h>
  #include <sys/time.h>
  
  #ifdef __sun
  # include <sys/filio.h>
  # include <sys/types.h>
  # include <sys/wait.h>
  #endif
  
  #if defined(__APPLE__)
  # include <sys/filio.h>
  # endif /* defined(__APPLE__) */
  
  
  #if defined(__APPLE__) && !TARGET_OS_IPHONE
  # include <crt_externs.h>
  # include <mach-o/dyld.h> /* _NSGetExecutablePath */
  # define environ (*_NSGetEnviron())
  #else /* defined(__APPLE__) && !TARGET_OS_IPHONE */
  extern char** environ;
  #endif /* !(defined(__APPLE__) && !TARGET_OS_IPHONE) */
  
  
  #if defined(__DragonFly__)      || \
      defined(__FreeBSD__)        || \
      defined(__FreeBSD_kernel__) || \
      defined(__NetBSD__)         || \
      defined(__OpenBSD__)
  # include <sys/sysctl.h>
  # include <sys/filio.h>
  # include <sys/wait.h>
  # if defined(__FreeBSD__)
  #  define uv__accept4 accept4
  # endif
  # if defined(__NetBSD__)
  #  define uv__accept4(a, b, c, d) paccept((a), (b), (c), NULL, (d))
  # endif
  #endif
  
  #if defined(__MVS__)
  #include <sys/ioctl.h>
  #endif
  
  #if defined(__linux__)
  # include <sys/syscall.h>
  # define uv__accept4 accept4
  #endif
  
  static int uv__run_pending(uv_loop_t* loop);
  
  /* Verify that uv_buf_t is ABI-compatible with struct iovec. */
  STATIC_ASSERT(sizeof(uv_buf_t) == sizeof(struct iovec));
  STATIC_ASSERT(sizeof(&((uv_buf_t*) 0)->base) ==
                sizeof(((struct iovec*) 0)->iov_base));
  STATIC_ASSERT(sizeof(&((uv_buf_t*) 0)->len) ==
                sizeof(((struct iovec*) 0)->iov_len));
  STATIC_ASSERT(offsetof(uv_buf_t, base) == offsetof(struct iovec, iov_base));
  STATIC_ASSERT(offsetof(uv_buf_t, len) == offsetof(struct iovec, iov_len));
  
  
  uint64_t uv_hrtime(void) {
    return uv__hrtime(UV_CLOCK_PRECISE);
  }
  
  
  void uv_close(uv_handle_t* handle, uv_close_cb close_cb) {
    assert(!uv__is_closing(handle));
  
    handle->flags |= UV_HANDLE_CLOSING;
    handle->close_cb = close_cb;
  
    switch (handle->type) {
    case UV_NAMED_PIPE:
      uv__pipe_close((uv_pipe_t*)handle);
      break;
  
    case UV_TTY:
      uv__stream_close((uv_stream_t*)handle);
      break;
  
    case UV_TCP:
      uv__tcp_close((uv_tcp_t*)handle);
      break;
  
    case UV_UDP:
      uv__udp_close((uv_udp_t*)handle);
      break;
  
    case UV_PREPARE:
      uv__prepare_close((uv_prepare_t*)handle);
      break;
  
    case UV_CHECK:
      uv__check_close((uv_check_t*)handle);
      break;
  
    case UV_IDLE:
      uv__idle_close((uv_idle_t*)handle);
      break;
  
    case UV_ASYNC:
      uv__async_close((uv_async_t*)handle);
      break;
  
    case UV_TIMER:
      uv__timer_close((uv_timer_t*)handle);
      break;
  
    case UV_PROCESS:
      uv__process_close((uv_process_t*)handle);
      break;
  
    case UV_FS_EVENT:
      uv__fs_event_close((uv_fs_event_t*)handle);
      break;
  
    case UV_POLL:
      uv__poll_close((uv_poll_t*)handle);
      break;
  
    case UV_FS_POLL:
      uv__fs_poll_close((uv_fs_poll_t*)handle);
      /* Poll handles use file system requests, and one of them may still be
       * running. The poll code will call uv__make_close_pending() for us. */
      return;
  
    case UV_SIGNAL:
      uv__signal_close((uv_signal_t*) handle);
      break;
  
    default:
      assert(0);
    }
  
    uv__make_close_pending(handle);
  }
  
  int uv__socket_sockopt(uv_handle_t* handle, int optname, int* value) {
    int r;
    int fd;
    socklen_t len;
  
    if (handle == NULL || value == NULL)
      return UV_EINVAL;
  
    if (handle->type == UV_TCP || handle->type == UV_NAMED_PIPE)
      fd = uv__stream_fd((uv_stream_t*) handle);
    else if (handle->type == UV_UDP)
      fd = ((uv_udp_t *) handle)->io_watcher.fd;
    else
      return UV_ENOTSUP;
  
    len = sizeof(*value);
  
    if (*value == 0)
      r = getsockopt(fd, SOL_SOCKET, optname, value, &len);
    else
      r = setsockopt(fd, SOL_SOCKET, optname, (const void*) value, len);
  
    if (r < 0)
      return UV__ERR(errno);
  
    return 0;
  }
  
  void uv__make_close_pending(uv_handle_t* handle) {
    assert(handle->flags & UV_HANDLE_CLOSING);
    assert(!(handle->flags & UV_HANDLE_CLOSED));
    handle->next_closing = handle->loop->closing_handles;
    handle->loop->closing_handles = handle;
  }
  
  int uv__getiovmax(void) {
  #if defined(IOV_MAX)
    return IOV_MAX;
  #elif defined(_SC_IOV_MAX)
    static int iovmax_cached = -1;
    int iovmax;
  
    iovmax = uv__load_relaxed(&iovmax_cached);
    if (iovmax != -1)
      return iovmax;
  
    /* On some embedded devices (arm-linux-uclibc based ip camera),
     * sysconf(_SC_IOV_MAX) can not get the correct value. The return
     * value is -1 and the errno is EINPROGRESS. Degrade the value to 1.
     */
    iovmax = sysconf(_SC_IOV_MAX);
    if (iovmax == -1)
      iovmax = 1;
  
    uv__store_relaxed(&iovmax_cached, iovmax);
  
    return iovmax;
  #else
    return 1024;
  #endif
  }
  
  
  static void uv__finish_close(uv_handle_t* handle) {
    uv_signal_t* sh;
  
    /* Note: while the handle is in the UV_HANDLE_CLOSING state now, it's still
     * possible for it to be active in the sense that uv__is_active() returns
     * true.
     *
     * A good example is when the user calls uv_shutdown(), immediately followed
     * by uv_close(). The handle is considered active at this point because the
     * completion of the shutdown req is still pending.
     */
    assert(handle->flags & UV_HANDLE_CLOSING);
    assert(!(handle->flags & UV_HANDLE_CLOSED));
    handle->flags |= UV_HANDLE_CLOSED;
  
    switch (handle->type) {
      case UV_PREPARE:
      case UV_CHECK:
      case UV_IDLE:
      case UV_ASYNC:
      case UV_TIMER:
      case UV_PROCESS:
      case UV_FS_EVENT:
      case UV_FS_POLL:
      case UV_POLL:
        break;
  
      case UV_SIGNAL:
        /* If there are any caught signals "trapped" in the signal pipe,
         * we can't call the close callback yet. Reinserting the handle
         * into the closing queue makes the event loop spin but that's
         * okay because we only need to deliver the pending events.
         */
        sh = (uv_signal_t*) handle;
        if (sh->caught_signals > sh->dispatched_signals) {
          handle->flags ^= UV_HANDLE_CLOSED;
          uv__make_close_pending(handle);  /* Back into the queue. */
          return;
        }
        break;
  
      case UV_NAMED_PIPE:
      case UV_TCP:
      case UV_TTY:
        uv__stream_destroy((uv_stream_t*)handle);
        break;
  
      case UV_UDP:
        uv__udp_finish_close((uv_udp_t*)handle);
        break;
  
      default:
        assert(0);
        break;
    }
  
    uv__handle_unref(handle);
    QUEUE_REMOVE(&handle->handle_queue);
  
    if (handle->close_cb) {
      handle->close_cb(handle);
    }
  }
  
  
  static void uv__run_closing_handles(uv_loop_t* loop) {
    uv_handle_t* p;
    uv_handle_t* q;
  
    p = loop->closing_handles;
    loop->closing_handles = NULL;
  
    while (p) {
      q = p->next_closing;
      uv__finish_close(p);
      p = q;
    }
  }
  
  
  int uv_is_closing(const uv_handle_t* handle) {
    return uv__is_closing(handle);
  }
  
  
  int uv_backend_fd(const uv_loop_t* loop) {
    return loop->backend_fd;
  }
  
  
  int uv_backend_timeout(const uv_loop_t* loop) {
    if (loop->stop_flag != 0)
      return 0;
  
    if (!uv__has_active_handles(loop) && !uv__has_active_reqs(loop))
      return 0;
  
    if (!QUEUE_EMPTY(&loop->idle_handles))
      return 0;
  
    if (!QUEUE_EMPTY(&loop->pending_queue))
      return 0;
  
    if (loop->closing_handles)
      return 0;
  
    return uv__next_timeout(loop);
  }
  
  
  static int uv__loop_alive(const uv_loop_t* loop) {
    return uv__has_active_handles(loop) ||
           uv__has_active_reqs(loop) ||
           loop->closing_handles != NULL;
  }
  
  
  int uv_loop_alive(const uv_loop_t* loop) {
      return uv__loop_alive(loop);
  }
  
  
  int uv_run(uv_loop_t* loop, uv_run_mode mode) {
    int timeout;
    int r;
    int ran_pending;
  
    r = uv__loop_alive(loop);
    if (!r)
      uv__update_time(loop);
  
    while (r != 0 && loop->stop_flag == 0) {
      uv__update_time(loop);
      uv__run_timers(loop);
      ran_pending = uv__run_pending(loop);
      uv__run_idle(loop);
      uv__run_prepare(loop);
  
      timeout = 0;
      if ((mode == UV_RUN_ONCE && !ran_pending) || mode == UV_RUN_DEFAULT)
        timeout = uv_backend_timeout(loop);
  
      uv__io_poll(loop, timeout);
  
      /* Run one final update on the provider_idle_time in case uv__io_poll
       * returned because the timeout expired, but no events were received. This
       * call will be ignored if the provider_entry_time was either never set (if
       * the timeout == 0) or was already updated b/c an event was received.
       */
      uv__metrics_update_idle_time(loop);
  
      uv__run_check(loop);
      uv__run_closing_handles(loop);
  
      if (mode == UV_RUN_ONCE) {
        /* UV_RUN_ONCE implies forward progress: at least one callback must have
         * been invoked when it returns. uv__io_poll() can return without doing
         * I/O (meaning: no callbacks) when its timeout expires - which means we
         * have pending timers that satisfy the forward progress constraint.
         *
         * UV_RUN_NOWAIT makes no guarantees about progress so it's omitted from
         * the check.
         */
        uv__update_time(loop);
        uv__run_timers(loop);
      }
  
      r = uv__loop_alive(loop);
      if (mode == UV_RUN_ONCE || mode == UV_RUN_NOWAIT)
        break;
    }
  
    /* The if statement lets gcc compile it to a conditional store. Avoids
     * dirtying a cache line.
     */
    if (loop->stop_flag != 0)
      loop->stop_flag = 0;
  
    return r;
  }
  
  
  #ifdef HAVE_LIBCAT
  int uv_crun(uv_loop_t* loop) {
    int timeout;
  
    if (!uv__loop_alive(loop)) {
      uv__update_time(loop);
      return 0;
    }
  
    if (uv__run_pending(loop)) {
      timeout = 0;
    } else {
      timeout = uv_backend_timeout(loop);
    }
    uv__run_idle(loop);
    uv__run_prepare(loop);
  
    uv__io_poll(loop, timeout);
  
    loop->round++;
    uv__update_time(loop);
    uv__run_timers(loop);
  
    uv__run_check(loop);
    uv__run_closing_handles(loop);
  
    return uv__loop_alive(loop);
  }
  #endif
  
  
  void uv_update_time(uv_loop_t* loop) {
    uv__update_time(loop);
  }
  
  
  int uv_is_active(const uv_handle_t* handle) {
    return uv__is_active(handle);
  }
  
  
  /* Open a socket in non-blocking close-on-exec mode, atomically if possible. */
  int uv__socket(int domain, int type, int protocol) {
    int sockfd;
    int err;
  
  #if defined(SOCK_NONBLOCK) && defined(SOCK_CLOEXEC)
    sockfd = socket(domain, type | SOCK_NONBLOCK | SOCK_CLOEXEC, protocol);
    if (sockfd != -1)
      return sockfd;
  
    if (errno != EINVAL)
      return UV__ERR(errno);
  #endif
  
    sockfd = socket(domain, type, protocol);
    if (sockfd == -1)
      return UV__ERR(errno);
  
    err = uv__nonblock(sockfd, 1);
    if (err == 0)
      err = uv__cloexec(sockfd, 1);
  
    if (err) {
      uv__close(sockfd);
      return err;
    }
  
  #if defined(SO_NOSIGPIPE)
    {
      int on = 1;
      setsockopt(sockfd, SOL_SOCKET, SO_NOSIGPIPE, &on, sizeof(on));
    }
  #endif
  
    return sockfd;
  }
  
  /* get a file pointer to a file in read-only and close-on-exec mode */
  FILE* uv__open_file(const char* path) {
    int fd;
    FILE* fp;
  
    fd = uv__open_cloexec(path, O_RDONLY);
    if (fd < 0)
      return NULL;
  
     fp = fdopen(fd, "r");
     if (fp == NULL)
       uv__close(fd);
  
     return fp;
  }
  
  
  int uv__accept(int sockfd) {
    int peerfd;
    int err;
  
    (void) &err;
    assert(sockfd >= 0);
  
    do
  #ifdef uv__accept4
      peerfd = uv__accept4(sockfd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
  #else
      peerfd = accept(sockfd, NULL, NULL);
  #endif
    while (peerfd == -1 && errno == EINTR);
  
    if (peerfd == -1)
      return UV__ERR(errno);
  
  #ifndef uv__accept4
    err = uv__cloexec(peerfd, 1);
    if (err == 0)
      err = uv__nonblock(peerfd, 1);
  
    if (err != 0) {
      uv__close(peerfd);
      return err;
    }
  #endif
  
    return peerfd;
  }
  
  
  /* close() on macos has the "interesting" quirk that it fails with EINTR
   * without closing the file descriptor when a thread is in the cancel state.
   * That's why libuv calls close$NOCANCEL() instead.
   *
   * glibc on linux has a similar issue: close() is a cancellation point and
   * will unwind the thread when it's in the cancel state. Work around that
   * by making the system call directly. Musl libc is unaffected.
   */
  int uv__close_nocancel(int fd) {
  #if defined(__APPLE__)
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wdollar-in-identifier-extension"
  #if defined(__LP64__) || TARGET_OS_IPHONE
    extern int close$NOCANCEL(int);
    return close$NOCANCEL(fd);
  #else
    extern int close$NOCANCEL$UNIX2003(int);
    return close$NOCANCEL$UNIX2003(fd);
  #endif
  #pragma GCC diagnostic pop
  #elif defined(__linux__)
    return syscall(SYS_close, fd);
  #else
    return close(fd);
  #endif
  }
  
  
  int uv__close_nocheckstdio(int fd) {
    int saved_errno;
    int rc;
  
    assert(fd > -1);  /* Catch uninitialized io_watcher.fd bugs. */
  
    saved_errno = errno;
    rc = uv__close_nocancel(fd);
    if (rc == -1) {
      rc = UV__ERR(errno);
      if (rc == UV_EINTR || rc == UV__ERR(EINPROGRESS))
        rc = 0;    /* The close is in progress, not an error. */
      errno = saved_errno;
    }
  
    return rc;
  }
  
  
  int uv__close(int fd) {
    assert(fd > STDERR_FILENO);  /* Catch stdio close bugs. */
  #if defined(__MVS__)
    SAVE_ERRNO(epoll_file_close(fd));
  #endif
    return uv__close_nocheckstdio(fd);
  }
  
  
  int uv__nonblock_ioctl(int fd, int set) {
    int r;
  
    do
      r = ioctl(fd, FIONBIO, &set);
    while (r == -1 && errno == EINTR);
  
    if (r)
      return UV__ERR(errno);
  
    return 0;
  }
  
  
  #if !defined(__CYGWIN__) && !defined(__MSYS__) && !defined(__HAIKU__)
  int uv__cloexec_ioctl(int fd, int set) {
    int r;
  
    do
      r = ioctl(fd, set ? FIOCLEX : FIONCLEX);
    while (r == -1 && errno == EINTR);
  
    if (r)
      return UV__ERR(errno);
  
    return 0;
  }
  #endif
  
  
  int uv__nonblock_fcntl(int fd, int set) {
    int flags;
    int r;
  
    do
      r = fcntl(fd, F_GETFL);
    while (r == -1 && errno == EINTR);
  
    if (r == -1)
      return UV__ERR(errno);
  
    /* Bail out now if already set/clear. */
    if (!!(r & O_NONBLOCK) == !!set)
      return 0;
  
    if (set)
      flags = r | O_NONBLOCK;
    else
      flags = r & ~O_NONBLOCK;
  
    do
      r = fcntl(fd, F_SETFL, flags);
    while (r == -1 && errno == EINTR);
  
    if (r)
      return UV__ERR(errno);
  
    return 0;
  }
  
  
  int uv__cloexec_fcntl(int fd, int set) {
    int flags;
    int r;
  
    do
      r = fcntl(fd, F_GETFD);
    while (r == -1 && errno == EINTR);
  
    if (r == -1)
      return UV__ERR(errno);
  
    /* Bail out now if already set/clear. */
    if (!!(r & FD_CLOEXEC) == !!set)
      return 0;
  
    if (set)
      flags = r | FD_CLOEXEC;
    else
      flags = r & ~FD_CLOEXEC;
  
    do
      r = fcntl(fd, F_SETFD, flags);
    while (r == -1 && errno == EINTR);
  
    if (r)
      return UV__ERR(errno);
  
    return 0;
  }
  
  
  ssize_t uv__recvmsg(int fd, struct msghdr* msg, int flags) {
    struct cmsghdr* cmsg;
    ssize_t rc;
    int* pfd;
    int* end;
  #if defined(__linux__)
    static int no_msg_cmsg_cloexec;
    if (0 == uv__load_relaxed(&no_msg_cmsg_cloexec)) {
      rc = recvmsg(fd, msg, flags | 0x40000000);  /* MSG_CMSG_CLOEXEC */
      if (rc != -1)
        return rc;
      if (errno != EINVAL)
        return UV__ERR(errno);
      rc = recvmsg(fd, msg, flags);
      if (rc == -1)
        return UV__ERR(errno);
      uv__store_relaxed(&no_msg_cmsg_cloexec, 1);
    } else {
      rc = recvmsg(fd, msg, flags);
    }
  #else
    rc = recvmsg(fd, msg, flags);
  #endif
    if (rc == -1)
      return UV__ERR(errno);
    if (msg->msg_controllen == 0)
      return rc;
    for (cmsg = CMSG_FIRSTHDR(msg); cmsg != NULL; cmsg = CMSG_NXTHDR(msg, cmsg))
      if (cmsg->cmsg_type == SCM_RIGHTS)
        for (pfd = (int*) CMSG_DATA(cmsg),
             end = (int*) ((char*) cmsg + cmsg->cmsg_len);
             pfd < end;
             pfd += 1)
          uv__cloexec(*pfd, 1);
    return rc;
  }
  
  
  int uv_cwd(char* buffer, size_t* size) {
    char scratch[1 + UV__PATH_MAX];
  
    if (buffer == NULL || size == NULL)
      return UV_EINVAL;
  
    /* Try to read directly into the user's buffer first... */
    if (getcwd(buffer, *size) != NULL)
      goto fixup;
  
    if (errno != ERANGE)
      return UV__ERR(errno);
  
    /* ...or into scratch space if the user's buffer is too small
     * so we can report how much space to provide on the next try.
     */
    if (getcwd(scratch, sizeof(scratch)) == NULL)
      return UV__ERR(errno);
  
    buffer = scratch;
  
  fixup:
  
    *size = strlen(buffer);
  
    if (*size > 1 && buffer[*size - 1] == '/') {
      *size -= 1;
      buffer[*size] = '\0';
    }
  
    if (buffer == scratch) {
      *size += 1;
      return UV_ENOBUFS;
    }
  
    return 0;
  }
  
  
  int uv_chdir(const char* dir) {
    if (chdir(dir))
      return UV__ERR(errno);
  
    return 0;
  }
  
  
  void uv_disable_stdio_inheritance(void) {
    int fd;
  
    /* Set the CLOEXEC flag on all open descriptors. Unconditionally try the
     * first 16 file descriptors. After that, bail out after the first error.
     */
    for (fd = 0; ; fd++)
      if (uv__cloexec(fd, 1) && fd > 15)
        break;
  }
  
  
  int uv_fileno(const uv_handle_t* handle, uv_os_fd_t* fd) {
    int fd_out;
  
    switch (handle->type) {
    case UV_TCP:
    case UV_NAMED_PIPE:
    case UV_TTY:
      fd_out = uv__stream_fd((uv_stream_t*) handle);
      break;
  
    case UV_UDP:
      fd_out = ((uv_udp_t *) handle)->io_watcher.fd;
      break;
  
    case UV_POLL:
      fd_out = ((uv_poll_t *) handle)->io_watcher.fd;
      break;
  
    default:
      return UV_EINVAL;
    }
  
    if (uv__is_closing(handle) || fd_out == -1)
      return UV_EBADF;
  
    *fd = fd_out;
    return 0;
  }
  
  
  static int uv__run_pending(uv_loop_t* loop) {
    QUEUE* q;
    QUEUE pq;
    uv__io_t* w;
  
    if (QUEUE_EMPTY(&loop->pending_queue))
      return 0;
  
    QUEUE_MOVE(&loop->pending_queue, &pq);
  
    while (!QUEUE_EMPTY(&pq)) {
      q = QUEUE_HEAD(&pq);
      QUEUE_REMOVE(q);
      QUEUE_INIT(q);
      w = QUEUE_DATA(q, uv__io_t, pending_queue);
      w->cb(loop, w, POLLOUT);
    }
  
    return 1;
  }
  
  
  static unsigned int next_power_of_two(unsigned int val) {
    val -= 1;
    val |= val >> 1;
    val |= val >> 2;
    val |= val >> 4;
    val |= val >> 8;
    val |= val >> 16;
    val += 1;
    return val;
  }
  
  static void maybe_resize(uv_loop_t* loop, unsigned int len) {
    uv__io_t** watchers;
    void* fake_watcher_list;
    void* fake_watcher_count;
    unsigned int nwatchers;
    unsigned int i;
  
    if (len <= loop->nwatchers)
      return;
  
    /* Preserve fake watcher list and count at the end of the watchers */
    if (loop->watchers != NULL) {
      fake_watcher_list = loop->watchers[loop->nwatchers];
      fake_watcher_count = loop->watchers[loop->nwatchers + 1];
    } else {
      fake_watcher_list = NULL;
      fake_watcher_count = NULL;
    }
  
    nwatchers = next_power_of_two(len + 2) - 2;
    watchers = uv__reallocf(loop->watchers,
                            (nwatchers + 2) * sizeof(loop->watchers[0]));
  
    if (watchers == NULL)
      abort();
    for (i = loop->nwatchers; i < nwatchers; i++)
      watchers[i] = NULL;
    watchers[nwatchers] = fake_watcher_list;
    watchers[nwatchers + 1] = fake_watcher_count;
  
    loop->watchers = watchers;
    loop->nwatchers = nwatchers;
  }
  
  
  void uv__io_init(uv__io_t* w, uv__io_cb cb, int fd) {
    assert(cb != NULL);
    assert(fd >= -1);
    QUEUE_INIT(&w->pending_queue);
    QUEUE_INIT(&w->watcher_queue);
    w->cb = cb;
    w->fd = fd;
    w->events = 0;
    w->pevents = 0;
  
  #if defined(UV_HAVE_KQUEUE)
    w->rcount = 0;
    w->wcount = 0;
  #endif /* defined(UV_HAVE_KQUEUE) */
  }
  
  
  void uv__io_start(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
    assert(0 == (events & ~(POLLIN | POLLOUT | UV__POLLRDHUP | UV__POLLPRI)));
    assert(0 != events);
    assert(w->fd >= 0);
    assert(w->fd < INT_MAX);
  
    w->pevents |= events;
    maybe_resize(loop, w->fd + 1);
  
  #if !defined(__sun)
    /* The event ports backend needs to rearm all file descriptors on each and
     * every tick of the event loop but the other backends allow us to
     * short-circuit here if the event mask is unchanged.
     */
    if (w->events == w->pevents)
      return;
  #endif
  
    if (QUEUE_EMPTY(&w->watcher_queue))
      QUEUE_INSERT_TAIL(&loop->watcher_queue, &w->watcher_queue);
  
    if (loop->watchers[w->fd] == NULL) {
      loop->watchers[w->fd] = w;
      loop->nfds++;
    }
  }
  
  
  void uv__io_stop(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
    assert(0 == (events & ~(POLLIN | POLLOUT | UV__POLLRDHUP | UV__POLLPRI)));
    assert(0 != events);
  
    if (w->fd == -1)
      return;
  
    assert(w->fd >= 0);
  
    /* Happens when uv__io_stop() is called on a handle that was never started. */
    if ((unsigned) w->fd >= loop->nwatchers)
      return;
  
    w->pevents &= ~events;
  
    if (w->pevents == 0) {
      QUEUE_REMOVE(&w->watcher_queue);
      QUEUE_INIT(&w->watcher_queue);
  
      if (loop->watchers[w->fd] != NULL) {
        assert(loop->watchers[w->fd] == w);
        assert(loop->nfds > 0);
        loop->watchers[w->fd] = NULL;
        loop->nfds--;
        w->events = 0;
      }
    }
    else if (QUEUE_EMPTY(&w->watcher_queue))
      QUEUE_INSERT_TAIL(&loop->watcher_queue, &w->watcher_queue);
  }
  
  
  void uv__io_close(uv_loop_t* loop, uv__io_t* w) {
    uv__io_stop(loop, w, POLLIN | POLLOUT | UV__POLLRDHUP | UV__POLLPRI);
    QUEUE_REMOVE(&w->pending_queue);
  
    /* Remove stale events for this file descriptor */
    if (w->fd != -1)
      uv__platform_invalidate_fd(loop, w->fd);
  }
  
  
  void uv__io_feed(uv_loop_t* loop, uv__io_t* w) {
    if (QUEUE_EMPTY(&w->pending_queue))
      QUEUE_INSERT_TAIL(&loop->pending_queue, &w->pending_queue);
  }
  
  
  int uv__io_active(const uv__io_t* w, unsigned int events) {
    assert(0 == (events & ~(POLLIN | POLLOUT | UV__POLLRDHUP | UV__POLLPRI)));
    assert(0 != events);
    return 0 != (w->pevents & events);
  }
  
  
  int uv__fd_exists(uv_loop_t* loop, int fd) {
    return (unsigned) fd < loop->nwatchers && loop->watchers[fd] != NULL;
  }
  
  
  int uv_getrusage(uv_rusage_t* rusage) {
    struct rusage usage;
  
    if (getrusage(RUSAGE_SELF, &usage))
      return UV__ERR(errno);
  
    rusage->ru_utime.tv_sec = usage.ru_utime.tv_sec;
    rusage->ru_utime.tv_usec = usage.ru_utime.tv_usec;
  
    rusage->ru_stime.tv_sec = usage.ru_stime.tv_sec;
    rusage->ru_stime.tv_usec = usage.ru_stime.tv_usec;
  
  #if !defined(__MVS__) && !defined(__HAIKU__)
    rusage->ru_maxrss = usage.ru_maxrss;
    rusage->ru_ixrss = usage.ru_ixrss;
    rusage->ru_idrss = usage.ru_idrss;
    rusage->ru_isrss = usage.ru_isrss;
    rusage->ru_minflt = usage.ru_minflt;
    rusage->ru_majflt = usage.ru_majflt;
    rusage->ru_nswap = usage.ru_nswap;
    rusage->ru_inblock = usage.ru_inblock;
    rusage->ru_oublock = usage.ru_oublock;
    rusage->ru_msgsnd = usage.ru_msgsnd;
    rusage->ru_msgrcv = usage.ru_msgrcv;
    rusage->ru_nsignals = usage.ru_nsignals;
    rusage->ru_nvcsw = usage.ru_nvcsw;
    rusage->ru_nivcsw = usage.ru_nivcsw;
  #endif
  
    return 0;
  }
  
  
  int uv__open_cloexec(const char* path, int flags) {
  #if defined(O_CLOEXEC)
    int fd;
  
    fd = open(path, flags | O_CLOEXEC);
    if (fd == -1)
      return UV__ERR(errno);
  
    return fd;
  #else  /* O_CLOEXEC */
    int err;
    int fd;
  
    fd = open(path, flags);
    if (fd == -1)
      return UV__ERR(errno);
  
    err = uv__cloexec(fd, 1);
    if (err) {
      uv__close(fd);
      return err;
    }
  
    return fd;
  #endif  /* O_CLOEXEC */
  }
  
  
  int uv__dup2_cloexec(int oldfd, int newfd) {
  #if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__linux__)
    int r;
  
    r = dup3(oldfd, newfd, O_CLOEXEC);
    if (r == -1)
      return UV__ERR(errno);
  
    return r;
  #else
    int err;
    int r;
  
    r = dup2(oldfd, newfd);  /* Never retry. */
    if (r == -1)
      return UV__ERR(errno);
  
    err = uv__cloexec(newfd, 1);
    if (err != 0) {
      uv__close(newfd);
      return err;
    }
  
    return r;
  #endif
  }
  
  
  int uv_os_homedir(char* buffer, size_t* size) {
    uv_passwd_t pwd;
    size_t len;
    int r;
  
    /* Check if the HOME environment variable is set first. The task of
       performing input validation on buffer and size is taken care of by
       uv_os_getenv(). */
    r = uv_os_getenv("HOME", buffer, size);
  
    if (r != UV_ENOENT)
      return r;
  
    /* HOME is not set, so call uv__getpwuid_r() */
    r = uv__getpwuid_r(&pwd);
  
    if (r != 0) {
      return r;
    }
  
    len = strlen(pwd.homedir);
  
    if (len >= *size) {
      *size = len + 1;
      uv_os_free_passwd(&pwd);
      return UV_ENOBUFS;
    }
  
    memcpy(buffer, pwd.homedir, len + 1);
    *size = len;
    uv_os_free_passwd(&pwd);
  
    return 0;
  }
  
  
  int uv_os_tmpdir(char* buffer, size_t* size) {
    const char* buf;
    size_t len;
  
    if (buffer == NULL || size == NULL || *size == 0)
      return UV_EINVAL;
  
  #define CHECK_ENV_VAR(name)                                                   \
    do {                                                                        \
      buf = getenv(name);                                                       \
      if (buf != NULL)                                                          \
        goto return_buffer;                                                     \
    }                                                                           \
    while (0)
  
    /* Check the TMPDIR, TMP, TEMP, and TEMPDIR environment variables in order */
    CHECK_ENV_VAR("TMPDIR");
    CHECK_ENV_VAR("TMP");
    CHECK_ENV_VAR("TEMP");
    CHECK_ENV_VAR("TEMPDIR");
  
  #undef CHECK_ENV_VAR
  
    /* No temp environment variables defined */
    #if defined(__ANDROID__)
      buf = "/data/local/tmp";
    #else
      buf = "/tmp";
    #endif
  
  return_buffer:
    len = strlen(buf);
  
    if (len >= *size) {
      *size = len + 1;
      return UV_ENOBUFS;
    }
  
    /* The returned directory should not have a trailing slash. */
    if (len > 1 && buf[len - 1] == '/') {
      len--;
    }
  
    memcpy(buffer, buf, len + 1);
    buffer[len] = '\0';
    *size = len;
  
    return 0;
  }
  
  
  int uv__getpwuid_r(uv_passwd_t* pwd) {
    struct passwd pw;
    struct passwd* result;
    char* buf;
    uid_t uid;
    size_t bufsize;
    size_t name_size;
    size_t homedir_size;
    size_t shell_size;
    long initsize;
    int r;
  
    if (pwd == NULL)
      return UV_EINVAL;
  
    initsize = sysconf(_SC_GETPW_R_SIZE_MAX);
  
    if (initsize <= 0)
      bufsize = 4096;
    else
      bufsize = (size_t) initsize;
  
    uid = geteuid();
    buf = NULL;
  
    for (;;) {
      uv__free(buf);
      buf = uv__malloc(bufsize);
  
      if (buf == NULL)
        return UV_ENOMEM;
  
      r = getpwuid_r(uid, &pw, buf, bufsize, &result);
  
      if (r != ERANGE)
        break;
  
      bufsize *= 2;
    }
  
    if (r != 0) {
      uv__free(buf);
      return -r;
    }
  
    if (result == NULL) {
      uv__free(buf);
      return UV_ENOENT;
    }
  
    /* Allocate memory for the username, shell, and home directory */
    name_size = strlen(pw.pw_name) + 1;
    homedir_size = strlen(pw.pw_dir) + 1;
    shell_size = strlen(pw.pw_shell) + 1;
    pwd->username = uv__malloc(name_size + homedir_size + shell_size);
  
    if (pwd->username == NULL) {
      uv__free(buf);
      return UV_ENOMEM;
    }
  
    /* Copy the username */
    memcpy(pwd->username, pw.pw_name, name_size);
  
    /* Copy the home directory */
    pwd->homedir = pwd->username + name_size;
    memcpy(pwd->homedir, pw.pw_dir, homedir_size);
  
    /* Copy the shell */
    pwd->shell = pwd->homedir + homedir_size;
    memcpy(pwd->shell, pw.pw_shell, shell_size);
  
    /* Copy the uid and gid */
    pwd->uid = pw.pw_uid;
    pwd->gid = pw.pw_gid;
  
    uv__free(buf);
  
    return 0;
  }
  
  
  void uv_os_free_passwd(uv_passwd_t* pwd) {
    if (pwd == NULL)
      return;
  
    /*
      The memory for name, shell, and homedir are allocated in a single
      uv__malloc() call. The base of the pointer is stored in pwd->username, so
      that is the field that needs to be freed.
    */
    uv__free(pwd->username);
    pwd->username = NULL;
    pwd->shell = NULL;
    pwd->homedir = NULL;
  }
  
  
  int uv_os_get_passwd(uv_passwd_t* pwd) {
    return uv__getpwuid_r(pwd);
  }
  
  
  int uv_translate_sys_error(int sys_errno) {
    /* If < 0 then it's already a libuv error. */
    return sys_errno <= 0 ? sys_errno : -sys_errno;
  }
  
  
  int uv_os_environ(uv_env_item_t** envitems, int* count) {
    int i, j, cnt;
    uv_env_item_t* envitem;
  
    *envitems = NULL;
    *count = 0;
  
    for (i = 0; environ[i] != NULL; i++);
  
    *envitems = uv__calloc(i, sizeof(**envitems));
  
    if (*envitems == NULL)
      return UV_ENOMEM;
  
    for (j = 0, cnt = 0; j < i; j++) {
      char* buf;
      char* ptr;
  
      if (environ[j] == NULL)
        break;
  
      buf = uv__strdup(environ[j]);
      if (buf == NULL)
        goto fail;
  
      ptr = strchr(buf, '=');
      if (ptr == NULL) {
        uv__free(buf);
        continue;
      }
  
      *ptr = '\0';
  
      envitem = &(*envitems)[cnt];
      envitem->name = buf;
      envitem->value = ptr + 1;
  
      cnt++;
    }
  
    *count = cnt;
    return 0;
  
  fail:
    for (i = 0; i < cnt; i++) {
      envitem = &(*envitems)[cnt];
      uv__free(envitem->name);
    }
    uv__free(*envitems);
  
    *envitems = NULL;
    *count = 0;
    return UV_ENOMEM;
  }
  
  
  int uv_os_getenv(const char* name, char* buffer, size_t* size) {
    char* var;
    size_t len;
  
    if (name == NULL || buffer == NULL || size == NULL || *size == 0)
      return UV_EINVAL;
  
    var = getenv(name);
  
    if (var == NULL)
      return UV_ENOENT;
  
    len = strlen(var);
  
    if (len >= *size) {
      *size = len + 1;
      return UV_ENOBUFS;
    }
  
    memcpy(buffer, var, len + 1);
    *size = len;
  
    return 0;
  }
  
  
  int uv_os_setenv(const char* name, const char* value) {
    if (name == NULL || value == NULL)
      return UV_EINVAL;
  
    if (setenv(name, value, 1) != 0)
      return UV__ERR(errno);
  
    return 0;
  }
  
  
  int uv_os_unsetenv(const char* name) {
    if (name == NULL)
      return UV_EINVAL;
  
    if (unsetenv(name) != 0)
      return UV__ERR(errno);
  
    return 0;
  }
  
  
  int uv_os_gethostname(char* buffer, size_t* size) {
    /*
      On some platforms, if the input buffer is not large enough, gethostname()
      succeeds, but truncates the result. libuv can detect this and return ENOBUFS
      instead by creating a large enough buffer and comparing the hostname length
      to the size input.
    */
    char buf[UV_MAXHOSTNAMESIZE];
    size_t len;
  
    if (buffer == NULL || size == NULL || *size == 0)
      return UV_EINVAL;
  
    if (gethostname(buf, sizeof(buf)) != 0)
      return UV__ERR(errno);
  
    buf[sizeof(buf) - 1] = '\0'; /* Null terminate, just to be safe. */
    len = strlen(buf);
  
    if (len >= *size) {
      *size = len + 1;
      return UV_ENOBUFS;
    }
  
    memcpy(buffer, buf, len + 1);
    *size = len;
    return 0;
  }
  
  
  uv_os_fd_t uv_get_osfhandle(int fd) {
    return fd;
  }
  
  int uv_open_osfhandle(uv_os_fd_t os_fd) {
    return os_fd;
  }
  
  uv_pid_t uv_os_getpid(void) {
    return getpid();
  }
  
  
  uv_pid_t uv_os_getppid(void) {
    return getppid();
  }
  
  
  int uv_os_getpriority(uv_pid_t pid, int* priority) {
    int r;
  
    if (priority == NULL)
      return UV_EINVAL;
  
    errno = 0;
    r = getpriority(PRIO_PROCESS, (int) pid);
  
    if (r == -1 && errno != 0)
      return UV__ERR(errno);
  
    *priority = r;
    return 0;
  }
  
  
  int uv_os_setpriority(uv_pid_t pid, int priority) {
    if (priority < UV_PRIORITY_HIGHEST || priority > UV_PRIORITY_LOW)
      return UV_EINVAL;
  
    if (setpriority(PRIO_PROCESS, (int) pid, priority) != 0)
      return UV__ERR(errno);
  
    return 0;
  }
  
  
  int uv_os_uname(uv_utsname_t* buffer) {
    struct utsname buf;
    int r;
  
    if (buffer == NULL)
      return UV_EINVAL;
  
    if (uname(&buf) == -1) {
      r = UV__ERR(errno);
      goto error;
    }
  
    r = uv__strscpy(buffer->sysname, buf.sysname, sizeof(buffer->sysname));
    if (r == UV_E2BIG)
      goto error;
  
  #ifdef _AIX
    r = snprintf(buffer->release,
                 sizeof(buffer->release),
                 "%s.%s",
                 buf.version,
                 buf.release);
    if (r >= sizeof(buffer->release)) {
      r = UV_E2BIG;
      goto error;
    }
  #else
    r = uv__strscpy(buffer->release, buf.release, sizeof(buffer->release));
    if (r == UV_E2BIG)
      goto error;
  #endif
  
    r = uv__strscpy(buffer->version, buf.version, sizeof(buffer->version));
    if (r == UV_E2BIG)
      goto error;
  
  #if defined(_AIX) || defined(__PASE__)
    r = uv__strscpy(buffer->machine, "ppc64", sizeof(buffer->machine));
  #else
    r = uv__strscpy(buffer->machine, buf.machine, sizeof(buffer->machine));
  #endif
  
    if (r == UV_E2BIG)
      goto error;
  
    return 0;
  
  error:
    buffer->sysname[0] = '\0';
    buffer->release[0] = '\0';
    buffer->version[0] = '\0';
    buffer->machine[0] = '\0';
    return r;
  }
  
  int uv__getsockpeername(const uv_handle_t* handle,
                          uv__peersockfunc func,
                          struct sockaddr* name,
                          int* namelen) {
    socklen_t socklen;
    uv_os_fd_t fd;
    int r;
  
    r = uv_fileno(handle, &fd);
    if (r < 0)
      return r;
  
    /* sizeof(socklen_t) != sizeof(int) on some systems. */
    socklen = (socklen_t) *namelen;
  
    if (func(fd, name, &socklen))
      return UV__ERR(errno);
  
    *namelen = (int) socklen;
    return 0;
  }
  
  int uv_gettimeofday(uv_timeval64_t* tv) {
    struct timeval time;
  
    if (tv == NULL)
      return UV_EINVAL;
  
    if (gettimeofday(&time, NULL) != 0)
      return UV__ERR(errno);
  
    tv->tv_sec = (int64_t) time.tv_sec;
    tv->tv_usec = (int32_t) time.tv_usec;
    return 0;
  }
  
  void uv_sleep(unsigned int msec) {
    struct timespec timeout;
    int rc;
  
    timeout.tv_sec = msec / 1000;
    timeout.tv_nsec = (msec % 1000) * 1000 * 1000;
  
    do
      rc = nanosleep(&timeout, &timeout);
    while (rc == -1 && errno == EINTR);
  
    assert(rc == 0);
  }
  
  int uv__search_path(const char* prog, char* buf, size_t* buflen) {
    char abspath[UV__PATH_MAX];
    size_t abspath_size;
    char trypath[UV__PATH_MAX];
    char* cloned_path;
    char* path_env;
    char* token;
  
    if (buf == NULL || buflen == NULL || *buflen == 0)
      return UV_EINVAL;
  
    /*
     * Possibilities for prog:
     * i) an absolute path such as: /home/user/myprojects/nodejs/node
     * ii) a relative path such as: ./node or ../myprojects/nodejs/node
     * iii) a bare filename such as "node", after exporting PATH variable
     *     to its location.
     */
  
    /* Case i) and ii) absolute or relative paths */
    if (strchr(prog, '/') != NULL) {
      if (realpath(prog, abspath) != abspath)
        return UV__ERR(errno);
  
      abspath_size = strlen(abspath);
  
      *buflen -= 1;
      if (*buflen > abspath_size)
        *buflen = abspath_size;
  
      memcpy(buf, abspath, *buflen);
      buf[*buflen] = '\0';
  
      return 0;
    } 
  
    /* Case iii). Search PATH environment variable */
    cloned_path = NULL;
    token = NULL;
    path_env = getenv("PATH");
  
    if (path_env == NULL)
      return UV_EINVAL;
  
    cloned_path = uv__strdup(path_env);
    if (cloned_path == NULL)
      return UV_ENOMEM;
  
    token = strtok(cloned_path, ":");
    while (token != NULL) {
      snprintf(trypath, sizeof(trypath) - 1, "%s/%s", token, prog);
      if (realpath(trypath, abspath) == abspath) {
        /* Check the match is executable */
        if (access(abspath, X_OK) == 0) {
          abspath_size = strlen(abspath);
  
          *buflen -= 1;
          if (*buflen > abspath_size)
            *buflen = abspath_size;
  
          memcpy(buf, abspath, *buflen);
          buf[*buflen] = '\0';
  
          uv__free(cloned_path);
          return 0;
        }
      }
      token = strtok(NULL, ":");
    }
    uv__free(cloned_path);
  
    /* Out of tokens (path entries), and no match found */
    return UV_EINVAL;
  }
  