text: // Copyright 2016 The Fuchsia Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef LIB_FDIO_INCLUDE_LIB_FDIO_WATCHER_H_
  #define LIB_FDIO_INCLUDE_LIB_FDIO_WATCHER_H_
  
  #include <lib/fdio/io.h>
  #include <zircon/compiler.h>
  
  __BEGIN_CDECLS
  
  typedef zx_status_t (*watchdir_func_t)(int dirfd, int event, const char* fn, void* cookie);
  
  // This event occurs when a file is added or removed, including
  // (for fdio_watch_directory()) files that already exist.
  #define WATCH_EVENT_ADD_FILE 1
  #define WATCH_EVENT_REMOVE_FILE 2
  
  // This event occurs, once, when fdio_watch_directory() runs
  // out of existing files and has to start waiting for new
  // files to be added.
  #define WATCH_EVENT_WAITING 3
  
  // Call the provided callback (cb) for each file in directory
  // and each time a new file is added to the directory.
  //
  // If the callback returns a status other than ZX_OK, watching
  // stops and the callback's status is returned to the caller
  // of fdio_watch_directory.
  //
  // If the deadline expires, ZX_ERR_TIMED_OUT is returned to the
  // caller.  A deadline of ZX_TIME_INFINITE will never expire.
  //
  // The callback may use ZX_ERR_STOP as a way to signal to the
  // caller that it wants to stop because it found what it was
  // looking for, etc -- since this error code is not returned
  // by syscalls or public APIs, the callback does not need to
  // worry about it turning up normally.
  
  zx_status_t fdio_watch_directory(int dirfd, watchdir_func_t cb, zx_time_t deadline, void* cookie);
  
  __END_CDECLS
  
  #endif  // LIB_FDIO_INCLUDE_LIB_FDIO_WATCHER_H_
  