oxmox
7063e2102e
git-subtree-dir: external/nng git-subtree-split: 29b73962b939a6fbbf6ea8d5d7680bb06d0eeb99
146 lines
5 KiB
Text
146 lines
5 KiB
Text
= nng_stream_get(3str)
|
|
//
|
|
// Copyright 2019 Staysail Systems, Inc. <info@staysail.tech>
|
|
// Copyright 2018 Capitar IT Group BV <info@capitar.com>
|
|
// Copyright 2019 Devolutions <info@devolutions.net>
|
|
//
|
|
// 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_stream_get - get option from byte stream
|
|
|
|
== SYNOPSIS
|
|
|
|
[source, c]
|
|
----
|
|
#include <nng/nng.h>
|
|
|
|
int nng_stream_get(nng_stream *s, const char *opt, void *val, size_t *sizep);
|
|
|
|
int nng_stream_get_bool(nng_stream *s, const char *opt, bool *valp);
|
|
|
|
int nng_stream_get_int(nng_stream *s, const char *opt, int *valp);
|
|
|
|
int nng_stream_get_ms(nng_stream *s, const char *opt, nng_duration *valp);
|
|
|
|
int nng_stream_get_ptr(nng_stream *s, const char *opt, void **valp);
|
|
|
|
int nng_stream_get_size(nng_stream *s, const char *opt, size_t *valp);
|
|
|
|
int nng_stream_get_addr(nng_stream *s, const char *opt, nng_sockaddr *valp);
|
|
|
|
int nng_stream_get_string(nng_stream *s, const char *opt, char **valp);
|
|
|
|
int nng_stream_get_uint64(nng_stream *s, const char *opt, uint64_t *valp);
|
|
|
|
----
|
|
|
|
== DESCRIPTION
|
|
|
|
The `nng_stream_get()` functions are used to retrieve option values for the
|
|
xref:nng_stream.5.adoc[byte stream] _conn_.
|
|
|
|
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)] and additional linked documents.
|
|
|
|
=== Forms
|
|
|
|
In all of these forms, the option _opt_ is retrieved from the connected
|
|
byte stream _s_.
|
|
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_stream_get()`::
|
|
This function is untyped and can be used to retrieve the value of any option.
|
|
The caller must store a pointer to a buffer to receive the value in _val_,
|
|
and the size of the buffer shall be stored at the location referenced by
|
|
_sizep_.
|
|
+
|
|
When the function returns, the actual size of the data copied (or that
|
|
would have been copied if sufficient space were present) is stored at
|
|
the location referenced by _sizep_.
|
|
If the caller's buffer is not large enough to hold the entire object,
|
|
then the copy is truncated.
|
|
Therefore the caller should check for truncation by verifying that the
|
|
returned size in _sizep_ does not exceed the original buffer size.
|
|
+
|
|
It is acceptable to pass `NULL` for _val_ if the value in _sizep_ is zero.
|
|
This can be used to determine the size of the buffer needed to receive
|
|
the object.
|
|
+
|
|
TIP: It may be easier to use one of the typed forms of this function.
|
|
|
|
`nng_stream_get_bool()`::
|
|
This function is for options which take a Boolean (`bool`).
|
|
|
|
`nng_stream_get_int()`::
|
|
This function is for options which take an integer (`int`).
|
|
|
|
`nng_stream_get_ms()`::
|
|
This function is used to retrieve time
|
|
xref:nng_duration.5.adoc[durations]
|
|
(such as timeouts), stored 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_stream_get_ptr()`::
|
|
This function is used to retrieve a pointer to structured data.
|
|
The data referenced is generally managed using other functions.
|
|
Note that this form is somewhat special in that the object is generally
|
|
not copied, but instead the *pointer* to the object is copied.
|
|
+
|
|
NOTE: Care must be taken to ensure that the application respects any
|
|
considerations about the lifetime of the underyling object.
|
|
See the documentation for the option for more specific guidance.
|
|
|
|
`nng_stream_get_size()`::
|
|
This function is used to retrieve a size,
|
|
typically for buffer sizes, message maximum sizes, and similar options.
|
|
|
|
`nng_stream_get_addr()`::
|
|
This function is used to retrieve a
|
|
xref:nng_sockaddr.5.adoc[socket address].
|
|
|
|
`nng_stream_get_string()`::
|
|
This function is used to retrieve a `NULL`-terminated string.
|
|
This string is created from the source using
|
|
xref:nng_strdup.3.adoc[`nng_strdup()`]
|
|
and consequently must be freed by the caller using
|
|
xref:nng_strfree.3.adoc[`nng_strfree()`] when it is no longer needed.
|
|
|
|
`nng_stream_get_uint64()`::
|
|
This function is used to retrieve a 64-bit unsigned value.
|
|
This is typically used for identifiers, network
|
|
numbers, and similar options.
|
|
|
|
== RETURN VALUES
|
|
|
|
This function returns 0 on success, and non-zero otherwise.
|
|
|
|
== ERRORS
|
|
|
|
[horizontal]
|
|
`NNG_ECLOSED`:: The connection is closed.
|
|
`NNG_EINVAL`:: There was insufficient space to receive the object.
|
|
The amount of data actually needed is returned in _sizep_.
|
|
`NNG_ENOTSUP`:: The option is not supported.
|
|
`NNG_EWRITEONLY`:: The option may not read.
|
|
|
|
== SEE ALSO
|
|
|
|
[.text-left]
|
|
xref:nng_strerror.3.adoc[nng_strerror(3)],
|
|
xref:nng_stream_set.3str.adoc[nng_stream_set(3str)],
|
|
xref:nng_options.5.adoc[nng_options(5)],
|
|
xref:nng_ipc_options.5.adoc[nng_ipc_options(5)],
|
|
xref:nng_tcp_options.5.adoc[nng_tcp_options(5)],
|
|
xref:nng_tls_options.5.adoc[nng_tls_options(5)],
|
|
xref:nng_stream.5.adoc[nng_stream(5)]
|