<lib/fdio/watcher.h> in fdio

WATCH_EVENT_ADD_FILE macro {:#WATCH_EVENT_ADD_FILE}

This event occurs when a file is added or removed, including (for fdio_watch_directory()) files that already exist.

WATCH_EVENT_REMOVE_FILE macro {:#WATCH_EVENT_REMOVE_FILE}

WATCH_EVENT_WAITING macro {:#WATCH_EVENT_WAITING}

This event occurs, once, when fdio_watch_directory() runs out of existing files and has to start waiting for new files to be added.

fdio_watch_directory(…) {:#fdio_watch_directory}

Declaration source code

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.