sd_event_get_fd

systemd
More text Zbigniew Jędrzejewski-Szmek zbyszek@in.waw.pl
sd_event_get_fd 3
sd_event_get_fd Obtain a file descriptor to poll for event loop events

    #include <systemd/sd-event.h>

int `sd_event_get_fd` sd_event *event

## Description

`sd_event_get_fd()` returns the file descriptor that an event loop object returned by the sd_event_new 3 function uses to wait for events. This file descriptor may itself be polled for `POLLIN`/`EPOLLIN` events. This makes it possible to embed an sd-event 3 event loop into another, possibly foreign, event loop.

The returned file descriptor refers to an epoll 7 object. It is recommended not to alter it by invoking epoll_ctl 2 on it, in order to avoid interference with the event loop's inner logic and assumptions.

## Return Value

On success, `sd_event_get_fd()` returns a non-negative file descriptor. On failure, it returns a negative errno-style error code.

## Errors

Returned errors may indicate the following problems:

`-EINVAL`

  event is not a valid pointer to an sd_event structure.

`-ECHILD`

  The event loop has been created in a different process.

## Examples

Integration in the GLib event loop

## See Also

sd-event 3, sd_event_new 3, sd_event_wait 3, epoll_ctl 3, epoll 7