C++ SAVE_ERRNO函数代码示例

uv_err_t uv_cpu_info(uv_cpu_info_t** cpu_infos, int* count) {
  unsigned int numcpus;
  uv_cpu_info_t* ci;

  *cpu_infos = NULL;
  *count = 0;

  numcpus = sysconf(_SC_NPROCESSORS_ONLN);
  assert(numcpus != (unsigned int)-1);
  assert(numcpus != 0);

  ci = calloc(numcpus, sizeof(*ci));
  if (ci == NULL) return uv__new_sys_error(ENOMEM);

  if (read_models(numcpus, ci)) {
    SAVE_ERRNO(uv_free_cpu_info(ci, numcpus));
    return uv__new_sys_error(errno);
  }

  if (read_times(numcpus, ci)) {
    SAVE_ERRNO(uv_free_cpu_info(ci, numcpus));
    return uv__new_sys_error(errno);
  }

  /* read_models() on x86 also reads the CPU speed from /proc/cpuinfo.
   * We don't check for errors here. Worst case, the field is left zero.
   */
  if (ci[0].speed == 0) read_speeds(numcpus, ci);

  *cpu_infos = ci;
  *count = numcpus;

  return uv_ok_;
}

int uv_cpu_info(uv_cpu_info_t** cpu_infos, int* count) {
  unsigned int ticks = (unsigned int)sysconf(_SC_CLK_TCK),
               multiplier = ((uint64_t)1000L / ticks), cpuspeed;
  uint64_t info[CPUSTATES];
  char model[512];
  int numcpus = 1;
  static int which[] = {CTL_HW,HW_MODEL,0};
  size_t size;
  int i;
  uv_cpu_info_t* cpu_info;

  size = sizeof(model);
  if (sysctl(which, 2, &model, &size, NULL, 0))
    return -errno;

  which[1] = HW_NCPU;
  size = sizeof(numcpus);
  if (sysctl(which, 2, &numcpus, &size, NULL, 0))
    return -errno;

  *cpu_infos = malloc(numcpus * sizeof(**cpu_infos));
  if (!(*cpu_infos))
    return -ENOMEM;

  *count = numcpus;

  which[1] = HW_CPUSPEED;
  size = sizeof(cpuspeed);
  if (sysctl(which, 2, &cpuspeed, &size, NULL, 0)) {
    SAVE_ERRNO(free(*cpu_infos));
    return -errno;
  }

  size = sizeof(info);
  which[0] = CTL_KERN;
  which[1] = KERN_CPTIME2;
  for (i = 0; i < numcpus; i++) {
    which[2] = i;
    size = sizeof(info);
    if (sysctl(which, 3, &info, &size, NULL, 0)) {
      SAVE_ERRNO(free(*cpu_infos));
      return -errno;
    }

    cpu_info = &(*cpu_infos)[i];
    
    cpu_info->cpu_times.user = (uint64_t)(info[CP_USER]) * multiplier;
    cpu_info->cpu_times.nice = (uint64_t)(info[CP_NICE]) * multiplier;
    cpu_info->cpu_times.sys = (uint64_t)(info[CP_SYS]) * multiplier;
    cpu_info->cpu_times.idle = (uint64_t)(info[CP_IDLE]) * multiplier;
    cpu_info->cpu_times.irq = (uint64_t)(info[CP_INTR]) * multiplier;

    cpu_info->model = strdup(model);
    cpu_info->speed = cpuspeed;
  }

  return 0;
}

int uv_exepath(char* buffer, size_t* size) {
  uint32_t usize;
  int result;
  char* path;
  char* fullpath;

  if (buffer == NULL || size == NULL)
    return -EINVAL;

  usize = *size;
  result = _NSGetExecutablePath(buffer, &usize);
  if (result) return result;

  path = malloc(2 * PATH_MAX);
  fullpath = realpath(buffer, path);
  if (fullpath == NULL) {
    SAVE_ERRNO(free(path));
    return -errno;
  }

  strncpy(buffer, fullpath, *size);
  free(fullpath);
  *size = strlen(buffer);
  return 0;
}

static void
invokeArray(JNIEnv* env, jlong ctxAddress, jbyteArray paramBuffer, void* returnBuffer)
{
    Function* ctx = (Function *) j2p(ctxAddress);

    void** ffiArgs = { NULL };
    jbyte *tmpBuffer = NULL;
    
    if (ctx->cif.nargs > 0) {
        unsigned int i;
        tmpBuffer = alloca(ctx->cif.nargs * PARAM_SIZE);
        ffiArgs = alloca(ctx->cif.nargs * sizeof(void *));
        
        (*env)->GetByteArrayRegion(env, paramBuffer, 0, ctx->cif.nargs * PARAM_SIZE, tmpBuffer);

        for (i = 0; i < ctx->cif.nargs; ++i) {
            if (unlikely(ctx->cif.arg_types[i]->type == FFI_TYPE_STRUCT)) {
                ffiArgs[i] = *(void **) &tmpBuffer[i * PARAM_SIZE];
            } else {
                ffiArgs[i] = &tmpBuffer[i * PARAM_SIZE];
            }
        }
    }

    ffi_call(&ctx->cif, FFI_FN(ctx->function), returnBuffer, ffiArgs);

    SAVE_ERRNO(ctx);
}

/*
 * Class:     com_kenai_jffi_Foreign
 * Method:    invokeArrayReturnStruct
 * Signature: (J[B[B)V
 */
JNIEXPORT void JNICALL
Java_com_kenai_jffi_Foreign_invokeArrayReturnStruct(JNIEnv* env, jclass self, jlong ctxAddress,
        jbyteArray paramBuffer, jbyteArray returnBuffer, jint offset)
{
    Function* ctx = (Function *) j2p(ctxAddress);
    jbyte* retval = alloca(ctx->cif.rtype->size);
    jbyte* tmpBuffer;
    void** ffiArgs;
    int i;

    //
    // Due to the undocumented and somewhat strange struct-return handling when
    // using ffi_raw_call(), we convert from raw to ptr array, then call via normal
    // ffi_call
    //

    ffiArgs = alloca(ctx->cif.nargs * sizeof(void *));

#ifdef USE_RAW
    tmpBuffer = alloca(ctx->rawParameterSize);
    (*env)->GetByteArrayRegion(env, paramBuffer, 0, ctx->rawParameterSize, tmpBuffer);
    for (i = 0; i < (int) ctx->cif.nargs; ++i) {
        ffiArgs[i] = (tmpBuffer + ctx->rawParamOffsets[i]);
    }
#else
    tmpBuffer = alloca(ctx->cif.nargs * PARAM_SIZE);
    (*env)->GetByteArrayRegion(env, paramBuffer, 0, ctx->cif.nargs * PARAM_SIZE, tmpBuffer);
    for (i = 0; i < (int) ctx->cif.nargs; ++i) {
        ffiArgs[i] = &tmpBuffer[i * PARAM_SIZE];
    }
#endif
    ffi_call(&ctx->cif, FFI_FN(ctx->function), retval, ffiArgs);
    SAVE_ERRNO(ctx);
    (*env)->SetByteArrayRegion(env, returnBuffer, offset, ctx->cif.rtype->size, retval);
}

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);
}

uv_err_t uv_resident_set_memory(size_t* rss) {
  char buf[1024];
  const char* s;
  ssize_t n;
  long val;
  int fd;
  int i;

  do
    fd = open("/proc/self/stat", O_RDONLY);
  while (fd == -1 && errno == EINTR);

  if (fd == -1)
    return uv__new_sys_error(errno);

  do
    n = read(fd, buf, sizeof(buf) - 1);
  while (n == -1 && errno == EINTR);

  SAVE_ERRNO(close(fd));
  if (n == -1)
    return uv__new_sys_error(errno);
  buf[n] = '\0';

  s = strchr(buf, ' ');
  if (s == NULL)
    goto err;

  s += 1;
  if (*s != '(')
    goto err;

  s = strchr(s, ')');
  if (s == NULL)
    goto err;

  for (i = 1; i <= 22; i++) {
    s = strchr(s + 1, ' ');
    if (s == NULL)
      goto err;
  }

  errno = 0;
  val = strtol(s, NULL, 10);
  if (errno != 0)
    goto err;
  if (val < 0)
    goto err;

  *rss = val * getpagesize();
  return uv_ok_;

err:
  return uv__new_artificial_error(UV_EINVAL);
}

/* This function is not execve-safe, there is a race window
 * between the call to dup() and fcntl(FD_CLOEXEC).
 */
int uv__dup(int fd) {
  fd = dup(fd);

  if (fd == -1)
    return -1;

  if (uv__cloexec(fd, 1)) {
    SAVE_ERRNO(uv__close(fd));
    return -1;
  }

  return fd;
}

static int new_inotify_fd(void) {
#if HAVE_INOTIFY_INIT1
  return inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
#else
  int fd;

  if ((fd = inotify_init()) == -1)
    return -1;

  if (uv__cloexec(fd, 1) || uv__nonblock(fd, 1)) {
    SAVE_ERRNO(uv__close(fd));
    fd = -1;
  }

  return fd;
#endif
}

static int new_inotify_fd(void) {
  int fd;

  fd = uv__inotify_init1(UV__IN_NONBLOCK | UV__IN_CLOEXEC);
  if (fd != -1)
    return fd;
  if (errno != ENOSYS)
    return -1;

  if ((fd = uv__inotify_init()) == -1)
    return -1;

  if (uv__cloexec(fd, 1) || uv__nonblock(fd, 1)) {
    SAVE_ERRNO(close(fd));
    return -1;
  }

  return fd;
}

void uv__io_poll(uv_loop_t* loop, int timeout) {
  struct pollfd events[1024];
  struct pollfd pqry;
  struct pollfd* pe;
  struct poll_ctl pc;
  QUEUE* q;
  uv__io_t* w;
  uint64_t base;
  uint64_t diff;
  int nevents;
  int count;
  int nfds;
  int i;
  int rc;
  int add_failed;

  if (loop->nfds == 0) {
    assert(QUEUE_EMPTY(&loop->watcher_queue));
    return;
  }

  while (!QUEUE_EMPTY(&loop->watcher_queue)) {
    q = QUEUE_HEAD(&loop->watcher_queue);
    QUEUE_REMOVE(q);
    QUEUE_INIT(q);

    w = QUEUE_DATA(q, uv__io_t, watcher_queue);
    assert(w->pevents != 0);
    assert(w->fd >= 0);
    assert(w->fd < (int) loop->nwatchers);

    pc.events = w->pevents;
    pc.fd = w->fd;

    add_failed = 0;
    if (w->events == 0) {
      pc.cmd = PS_ADD;
      if (pollset_ctl(loop->backend_fd, &pc, 1)) {
        if (errno != EINVAL) {
          assert(0 && "Failed to add file descriptor (pc.fd) to pollset");
          abort();
        }
        /* Check if the fd is already in the pollset */
        pqry.fd = pc.fd;
        rc = pollset_query(loop->backend_fd, &pqry);
        switch (rc) {
        case -1: 
          assert(0 && "Failed to query pollset for file descriptor");
          abort();
        case 0:
          assert(0 && "Pollset does not contain file descriptor");
          abort();
        }
        /* If we got here then the pollset already contained the file descriptor even though
         * we didn't think it should. This probably shouldn't happen, but we can continue. */
        add_failed = 1;
      }
    }
    if (w->events != 0 || add_failed) {
      /* Modify, potentially removing events -- need to delete then add.
       * Could maybe mod if we knew for sure no events are removed, but
       * content of w->events is handled above as not reliable (falls back)
       * so may require a pollset_query() which would have to be pretty cheap
       * compared to a PS_DELETE to be worth optimizing. Alternatively, could
       * lazily remove events, squelching them in the mean time. */
      pc.cmd = PS_DELETE;
      if (pollset_ctl(loop->backend_fd, &pc, 1)) {
        assert(0 && "Failed to delete file descriptor (pc.fd) from pollset");
        abort();
      }
      pc.cmd = PS_ADD;
      if (pollset_ctl(loop->backend_fd, &pc, 1)) {
        assert(0 && "Failed to add file descriptor (pc.fd) to pollset");
        abort();
      }
    }

    w->events = w->pevents;
  }

  assert(timeout >= -1);
  base = loop->time;
  count = 48; /* Benchmarks suggest this gives the best throughput. */

  for (;;) {
    nfds = pollset_poll(loop->backend_fd,
                        events,
                        ARRAY_SIZE(events),
                        timeout);

    /* Update loop->time unconditionally. It's tempting to skip the update when
     * timeout == 0 (i.e. non-blocking poll) but there is no guarantee that the
     * operating system didn't reschedule our process while in the syscall.
     */
    SAVE_ERRNO(uv__update_time(loop));

    if (nfds == 0) {
      assert(timeout != -1);
      return;
    }
//.........这里部分代码省略.........

void uv__io_poll(uv_loop_t* loop, int timeout) {
  struct kevent events[1024];
  struct kevent* ev;
  struct timespec spec;
  unsigned int nevents;
  unsigned int revents;
  QUEUE* q;
  uint64_t base;
  uint64_t diff;
  uv__io_t* w;
  int filter;
  int fflags;
  int count;
  int nfds;
  int fd;
  int op;
  int i;

  if (loop->nfds == 0) {
    assert(QUEUE_EMPTY(&loop->watcher_queue));
    return;
  }

  nevents = 0;

  while (!QUEUE_EMPTY(&loop->watcher_queue)) {
    q = QUEUE_HEAD(&loop->watcher_queue);
    QUEUE_REMOVE(q);
    QUEUE_INIT(q);

    w = QUEUE_DATA(q, uv__io_t, watcher_queue);
    assert(w->pevents != 0);
    assert(w->fd >= 0);
    assert(w->fd < (int) loop->nwatchers);

    if ((w->events & UV__POLLIN) == 0 && (w->pevents & UV__POLLIN) != 0) {
      filter = EVFILT_READ;
      fflags = 0;
      op = EV_ADD;

      if (w->cb == uv__fs_event) {
        filter = EVFILT_VNODE;
        fflags = NOTE_ATTRIB | NOTE_WRITE  | NOTE_RENAME
               | NOTE_DELETE | NOTE_EXTEND | NOTE_REVOKE;
        op = EV_ADD | EV_ONESHOT; /* Stop the event from firing repeatedly. */
      }

      EV_SET(events + nevents, w->fd, filter, op, fflags, 0, 0);

      if (++nevents == ARRAY_SIZE(events)) {
        if (kevent(loop->backend_fd, events, nevents, NULL, 0, NULL))
          abort();
        nevents = 0;
      }
    }

    if ((w->events & UV__POLLOUT) == 0 && (w->pevents & UV__POLLOUT) != 0) {
      EV_SET(events + nevents, w->fd, EVFILT_WRITE, EV_ADD, 0, 0, 0);

      if (++nevents == ARRAY_SIZE(events)) {
        if (kevent(loop->backend_fd, events, nevents, NULL, 0, NULL))
          abort();
        nevents = 0;
      }
    }

    w->events = w->pevents;
  }

  assert(timeout >= -1);
  base = loop->time;
  count = 48; /* Benchmarks suggest this gives the best throughput. */

  for (;; nevents = 0) {
    if (timeout != -1) {
      spec.tv_sec = timeout / 1000;
      spec.tv_nsec = (timeout % 1000) * 1000000;
    }

    nfds = kevent(loop->backend_fd,
                  events,
                  nevents,
                  events,
                  ARRAY_SIZE(events),
                  timeout == -1 ? NULL : &spec);

    /* Update loop->time unconditionally. It's tempting to skip the update when
     * timeout == 0 (i.e. non-blocking poll) but there is no guarantee that the
     * operating system didn't reschedule our process while in the syscall.
     */
    SAVE_ERRNO(uv__update_time(loop));

    if (nfds == 0) {
      assert(timeout != -1);
      return;
    }

    if (nfds == -1) {
      if (errno != EINTR)
        abort();
//.........这里部分代码省略.........

/* execvp is marked __WATCHOS_PROHIBITED __TVOS_PROHIBITED, so must be
 * avoided. Since this isn't called on those targets, the function
 * doesn't even need to be defined for them.
 */
static void uv__process_child_init(const uv_process_options_t* options,
                                   int stdio_count,
                                   int (*pipes)[2],
                                   int error_fd) {
  sigset_t set;
  int close_fd;
  int use_fd;
  int err;
  int fd;
  int n;
#if defined(__linux__) || defined(__FreeBSD__)
  int r;
  int i;
  int cpumask_size;
  uv__cpu_set_t cpuset;
#endif

  if (options->flags & UV_PROCESS_DETACHED)
    setsid();

  /* First duplicate low numbered fds, since it's not safe to duplicate them,
   * they could get replaced. Example: swapping stdout and stderr; without
   * this fd 2 (stderr) would be duplicated into fd 1, thus making both
   * stdout and stderr go to the same fd, which was not the intention. */
  for (fd = 0; fd < stdio_count; fd++) {
    use_fd = pipes[fd][1];
    if (use_fd < 0 || use_fd >= fd)
      continue;
    pipes[fd][1] = fcntl(use_fd, F_DUPFD, stdio_count);
    if (pipes[fd][1] == -1) {
      uv__write_int(error_fd, UV__ERR(errno));
      _exit(127);
    }
  }

  for (fd = 0; fd < stdio_count; fd++) {
    close_fd = pipes[fd][0];
    use_fd = pipes[fd][1];

    if (use_fd < 0) {
      if (fd >= 3)
        continue;
      else {
        /* redirect stdin, stdout and stderr to /dev/null even if UV_IGNORE is
         * set
         */
        use_fd = open("/dev/null", fd == 0 ? O_RDONLY : O_RDWR);
        close_fd = use_fd;

        if (use_fd == -1) {
          uv__write_int(error_fd, UV__ERR(errno));
          _exit(127);
        }
      }
    }

    if (fd == use_fd)
      uv__cloexec_fcntl(use_fd, 0);
    else
      fd = dup2(use_fd, fd);

    if (fd == -1) {
      uv__write_int(error_fd, UV__ERR(errno));
      _exit(127);
    }

    if (fd <= 2)
      uv__nonblock_fcntl(fd, 0);

    if (close_fd >= stdio_count)
      uv__close(close_fd);
  }

  for (fd = 0; fd < stdio_count; fd++) {
    use_fd = pipes[fd][1];

    if (use_fd >= stdio_count)
      uv__close(use_fd);
  }

  if (options->cwd != NULL && chdir(options->cwd)) {
    uv__write_int(error_fd, UV__ERR(errno));
    _exit(127);
  }

  if (options->flags & (UV_PROCESS_SETUID | UV_PROCESS_SETGID)) {
    /* When dropping privileges from root, the `setgroups` call will
     * remove any extraneous groups. If we don't call this, then
     * even though our uid has dropped, we may still have groups
     * that enable us to do super-user things. This will fail if we
     * aren't root, so don't bother checking the return value, this
     * is just done as an optimistic privilege dropping function.
     */
    SAVE_ERRNO(setgroups(0, NULL));
  }

//.........这里部分代码省略.........

//.........这里部分代码省略.........
        int idx = (type & com_kenai_jffi_ObjectBuffer_INDEX_MASK) >> com_kenai_jffi_ObjectBuffer_INDEX_SHIFT;
        void* ptr;

        switch (type & com_kenai_jffi_ObjectBuffer_TYPE_MASK & ~com_kenai_jffi_ObjectBuffer_PRIM_MASK) {
            case com_kenai_jffi_ObjectBuffer_ARRAY:
                if (unlikely(object == NULL)) {
                    throwException(env, NullPointer, "null object for parameter %d", idx);
                    goto cleanup;
                
                } else if (unlikely((type & com_kenai_jffi_ObjectBuffer_PINNED) != 0)) {

                    ptr = jffi_getArrayCritical(env, object, offset, length, type, &arrays[arrayCount]);
                    if (unlikely(ptr == NULL)) {
                        goto cleanup;
                    }
                } else if (true && likely(length < MAX_STACK_ARRAY)) {

                    ptr = alloca(jffi_arraySize(length + 1, type));
                    if (unlikely(jffi_getArrayBuffer(env, object, offset, length, type,
                        &arrays[arrayCount], ptr) == NULL)) {
                        goto cleanup;
                    }

                } else {
                    ptr = jffi_getArrayHeap(env, object, offset, length, type, &arrays[arrayCount]);
                    if (unlikely(ptr == NULL)) {
                        goto cleanup;
                    }
                }
                
                ++arrayCount;
                break;

            case com_kenai_jffi_ObjectBuffer_BUFFER:
                ptr = (*env)->GetDirectBufferAddress(env, object);
                if (unlikely(ptr == NULL)) {
                    throwException(env, NullPointer, "Could not get direct Buffer address");
                    goto cleanup;
                }
                ptr = ((char *) ptr + offset);
                break;

            case com_kenai_jffi_ObjectBuffer_JNI:
                switch (type & com_kenai_jffi_ObjectBuffer_TYPE_MASK) {
                    case com_kenai_jffi_ObjectBuffer_JNIENV:
                        ptr = env;
                        break;
                    case com_kenai_jffi_ObjectBuffer_JNIOBJECT:
                        ptr = (void *) object;
                        break;
                    default:
                        throwException(env, IllegalArgument, "Unsupported object type: %#x",
                            type & com_kenai_jffi_ObjectBuffer_TYPE_MASK);
                        goto cleanup;
                }
                
                break;
            default:
                throwException(env, IllegalArgument, "Unsupported object type: %#x", 
                        type & com_kenai_jffi_ObjectBuffer_TYPE_MASK);
                goto cleanup;
        }

#if defined(USE_RAW)
        *((void **)(tmpBuffer + ctx->rawParamOffsets[idx])) = ptr;
#else
        if (unlikely(ctx->cif.arg_types[idx]->type == FFI_TYPE_STRUCT)) {
            ffiArgs[idx] = ptr;
        } else {
            *((void **) ffiArgs[idx]) = ptr;
        }
#endif
    }
#if defined(USE_RAW)
    //
    // Special case for struct return values - unroll into a ptr array and
    // use ffi_call, since ffi_raw_call with struct return values is undocumented.
    //
    if (unlikely(ctx->cif.rtype->type == FFI_TYPE_STRUCT)) {
        ffiArgs = alloca(ctx->cif.nargs * sizeof(void *));
        for (i = 0; i < ctx->cif.nargs; ++i) {
            ffiArgs[i] = (tmpBuffer + ctx->rawParamOffsets[i]);
        }
        ffi_call(&ctx->cif, FFI_FN(ctx->function), retval, ffiArgs);
    } else {
        ffi_raw_call(&ctx->cif, FFI_FN(ctx->function), retval, (ffi_raw *) tmpBuffer);
    }
#else
    ffi_call(&ctx->cif, FFI_FN(ctx->function), retval, ffiArgs);
#endif
    SAVE_ERRNO(ctx);
cleanup:
    /* Release any array backing memory */
    for (i = 0; i < arrayCount; ++i) {
        if (arrays[i].release != NULL) {
            //printf("releasing array=%p\n", arrays[i].elems);
            (*arrays[i].release)(env, &arrays[i]);
        }
    }
}

void uv__io_poll(uv_loop_t* loop, int timeout) {
  struct port_event events[1024];
  struct port_event* pe;
  struct timespec spec;
  QUEUE* q;
  uv__io_t* w;
  uint64_t base;
  uint64_t diff;
  unsigned int nfds;
  unsigned int i;
  int saved_errno;
  int nevents;
  int count;
  int fd;

  if (loop->nfds == 0) {
    assert(QUEUE_EMPTY(&loop->watcher_queue));
    return;
  }

  while (!QUEUE_EMPTY(&loop->watcher_queue)) {
    q = QUEUE_HEAD(&loop->watcher_queue);
    QUEUE_REMOVE(q);
    QUEUE_INIT(q);

    w = QUEUE_DATA(q, uv__io_t, watcher_queue);
    assert(w->pevents != 0);

    if (port_associate(loop->backend_fd, PORT_SOURCE_FD, w->fd, w->pevents, 0))
      abort();

    w->events = w->pevents;
  }

  assert(timeout >= -1);
  base = loop->time;
  count = 48; /* Benchmarks suggest this gives the best throughput. */

  for (;;) {
    if (timeout != -1) {
      spec.tv_sec = timeout / 1000;
      spec.tv_nsec = (timeout % 1000) * 1000000;
    }

    /* Work around a kernel bug where nfds is not updated. */
    events[0].portev_source = 0;

    nfds = 1;
    saved_errno = 0;
    if (port_getn(loop->backend_fd,
                  events,
                  ARRAY_SIZE(events),
                  &nfds,
                  timeout == -1 ? NULL : &spec)) {
      /* Work around another kernel bug: port_getn() may return events even
       * on error.
       */
      if (errno == EINTR || errno == ETIME)
        saved_errno = errno;
      else
        abort();
    }

    /* Update loop->time unconditionally. It's tempting to skip the update when
     * timeout == 0 (i.e. non-blocking poll) but there is no guarantee that the
     * operating system didn't reschedule our process while in the syscall.
     */
    SAVE_ERRNO(uv__update_time(loop));

    if (events[0].portev_source == 0) {
      if (timeout == 0)
        return;

      if (timeout == -1)
        continue;

      goto update_timeout;
    }

    if (nfds == 0) {
      assert(timeout != -1);
      return;
    }

    nevents = 0;

    for (i = 0; i < nfds; i++) {
      pe = events + i;
      fd = pe->portev_object;

      assert(fd >= 0);
      assert((unsigned) fd < loop->nwatchers);

      w = loop->watchers[fd];

      /* File descriptor that we've stopped watching, ignore. */
      if (w == NULL)
        continue;

      w->cb(loop, w, pe->portev_events);
//.........这里部分代码省略.........