[#ASYNC_WAIT_CTX_set_wait_fd]
= ASYNC_WAIT_CTX_set_wait_fd
:mrdocs:

Associate a waitable file descriptor with a key in the wait context.

== Synopsis

Declared in `<openssl/async.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
ASYNC_WAIT_CTX_set_wait_fd(
    xref:ASYNC_WAIT_CTX.adoc[ASYNC_WAIT_CTX]* ctx,
    void const* key,
    int fd,
    void* custom_data,
    void(* cleanup)(xref:ASYNC_WAIT_CTX.adoc[ASYNC_WAIT_CTX]*, void const*, int, void*));
----

== Return Value

1 on success, or 0 on error.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| Wait context to update.
| *key*
| Unique key identifying this wait fd.
| *fd*
| File descriptor to wait on.
| *custom_data*
| Optional application data for the cleanup callback.
| *cleanup*
| Optional callback to release `custom_data` when the fd is cleared.
|===


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