main/syscalls/event_create.md

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# zx_event_create

## Summary

Create an event.

## Declaration

```c
#include <zircon/syscalls.h>

zx_status_t zx_event_create(uint32_t options, zx_handle_t* out);
```

## Description

`zx_event_create()` creates an event, which is an object that is signalable. That
is, the signals `ZX_EVENT_SIGNALED` and `ZX_USER_SIGNAL_n` (where *n* is 0 through
7) can be manipulated using [`zx_object_signal()`].

The newly-created handle will have the [basic
rights](/docs/concepts/kernel/rights.md#zx_rights_basic) plus `ZX_RIGHT_SIGNAL`.

## Rights

Caller job policy must allow `ZX_POL_NEW_EVENT`.

## Return value

`zx_event_create()` returns `ZX_OK` and a valid event handle (via *out*) on success.
On failure, an error value is returned.

## Errors

`ZX_ERR_INVALID_ARGS`  *out* is an invalid pointer, or *options* is nonzero.

`ZX_ERR_NO_MEMORY`  Failure due to lack of memory.
There is no good way for userspace to handle this (unlikely) error.
In a future build this error will no longer occur.

## See also

 - [`zx_eventpair_create()`]
 - [`zx_handle_close()`]
 - [`zx_handle_duplicate()`]
 - [`zx_handle_replace()`]
 - [`zx_object_signal()`]
 - [`zx_object_wait_async()`]
 - [`zx_object_wait_many()`]
 - [`zx_object_wait_one()`]

[`zx_eventpair_create()`]: eventpair_create.md
[`zx_handle_close()`]: handle_close.md
[`zx_handle_duplicate()`]: handle_duplicate.md
[`zx_handle_replace()`]: handle_replace.md
[`zx_object_signal()`]: object_signal.md
[`zx_object_wait_async()`]: object_wait_async.md
[`zx_object_wait_many()`]: object_wait_many.md
[`zx_object_wait_one()`]: object_wait_one.md