= nng_ctx_get(3)
//
// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
// Copyright 2018 Capitar IT Group BV <info@capitar.com>
//
// This document is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt).  A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//

== NAME

nng_ctx_get - get context option

== SYNOPSIS

[source, c]
----
#include <nng/nng.h>

int nng_ctx_get_bool(nng_ctx ctx, const char *opt, bool *bvalp);

int nng_ctx_get_int(nng_ctx ctx, const char *opt, int *ivalp);

int nng_ctx_get_ms(nng_ctx ctx, const char *opt, nng_duration *durp);

int nng_ctx_get_size(nng_ctx ctx, const char *opt, size_t *zp);

int nng_ctx_get_uint64(nng_ctx ctx, const char *opt, uint64_t *u64p);

----

== DESCRIPTION

(((options, context)))
The `nng_ctx_get` functions are used to retrieve option values for
the xref:nng_ctx.5.adoc[context] _ctx_.
The actual options that may be retrieved in this way vary.
A number of them are documented in xref:nng_options.5.adoc[nng_options(5)].

NOTE: Context options are protocol specific.
The details will be documented with the protocol.

=== Forms

In all of these forms, the option _opt_ is retrieved from the context _ctx_.
The forms vary based on the type of the option they take.

The details of the type, size, and semantics of the option will depend
on the actual option, and will be documented with the option itself.

`nng_ctx_get_bool()`::
This function is for options which take a Boolean (`bool`).
The value will be stored at _ivalp_.

`nng_ctx_get_int()`::
This function is for options which take an integer (`int`).
The value will be stored at _ivalp_.

`nng_ctx_get_ms()`::
This function is used to retrieve time xref:nng_duration.5.adoc[durations]
(such as timeouts), stored in _durp_ as a number of milliseconds.
(The special value ((`NNG_DURATION_INFINITE`)) means an infinite amount of time, and
the special value ((`NNG_DURATION_DEFAULT`)) means a context-specific default.)

`nng_ctx_get_size()`::
This function is used to retrieve a size into the pointer _zp_,
typically for buffer sizes, message maximum sizes, and similar options.

`nng_ctx_get_uint64()`::
This function is used to retrieve a 64-bit unsigned value into the value
referenced by _u64p_.
This is typically used for options related to identifiers, network
numbers, and similar.

== RETURN VALUES

These functions return 0 on success, and non-zero otherwise.

== ERRORS

[horizontal]
`NNG_EBADTYPE`:: Incorrect type for option.
`NNG_ECLOSED`:: Parameter _s_ does not refer to an open socket.
`NNG_EINVAL`:: Size of destination _val_ too small for object.
`NNG_ENOMEM`:: Insufficient memory exists.
`NNG_ENOTSUP`:: The option _opt_ is not supported.
`NNG_EWRITEONLY`:: The option _opt_ is write-only.

== SEE ALSO

[.text-left]
xref:nng_ctx_set.3.adoc[nng_ctx_set(3)],
xref:nng_strdup.3.adoc[nng_strdup(3)],
xref:nng_strerror.3.adoc[nng_strerror(3)],
xref:nng_strfree.3.adoc[nng_strfree(3)],
xref:nng_duration.5.adoc[nng_duration(5)],
xref:nng_ctx.5.adoc[nng_ctx(5)],
xref:nng_options.5.adoc[nng_options(5)],
xref:nng.7.adoc[nng(7)]
