diff options
Diffstat (limited to 'docs/man/nng_socket_get.3.adoc')
| -rw-r--r-- | docs/man/nng_socket_get.3.adoc | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/docs/man/nng_socket_get.3.adoc b/docs/man/nng_socket_get.3.adoc new file mode 100644 index 00000000..d077207d --- /dev/null +++ b/docs/man/nng_socket_get.3.adoc @@ -0,0 +1,144 @@ += nng_socket_get(3) +// +// Copyright 2018 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_socket_get - get socket option + +== SYNOPSIS + +[source, c] +---- +#include <nng/nng.h> + +int nng_socket_get(nng_socket s, const char *opt, void *val, size_t *valszp); + +int nng_socket_get_bool(nng_socket s, const char *opt, bool *bvalp); + +int nng_socket_get_int(nng_socket s, const char *opt, int *ivalp); + +int nng_socket_get_size(nng_socket s, const char *opt, size_t *zp); + +int nng_socket_get_uint64(nng_socket s, const char *opt, uint64_t *u64p); + +int nng_socket_get_string(nng_socket s, const char *opt, char **strp); + +int nng_socket_get_ptr(nng_socket s, const char *opt, void **ptr); + +int nng_socket_get_ms(nng_socket s, const char *opt, nng_duration *durp); + +int nng_socket_get_addr(nng_socket s, const char *opt, nng_sockaddr *addrp); + +---- + +== DESCRIPTION + +(((options, socket))) +The `nng_socket_get()` functions are used to retrieve option values for +the <<nng_socket.5#,socket>> _s_. +The actual options that may be retrieved in this way vary. +A number of them are documented in <<nng_options.5#,nng_options(5)>>. + +Additionally transport-specific options and protocol-specific options are +documented with the transports and protocols themselves. + +=== Forms + +In all of these forms, the option _opt_ is retrieved from the socket _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_socket_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 +_valszp_. ++ +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 _valszp_. +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 _valszp_ does not exceed the original buffer size. ++ +It is acceptable to pass `NULL` for _val_ if the value in _valszp_ 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_socket_get_bool()`:: +This function is for options which take a Boolean (`bool`). +The value will be stored at _bvalp_. + +`nng_socket_get_int()`:: +This function is for options which take an integer (`int`). +The value will be stored at _ivalp_. + +`nng_socket_get_ms()`:: +This function is used to retrieve time <<nng_duration.5#,durations>> +(such as timeouts), stored in _durp_ as a number of milliseconds. +(The special value ((`NNG_DUR_INFINITE`)) means an infinite amount of time, and +the special value ((`NNG_DUR_DEFAULT`)) means a context-specific default.) + +`nng_socket_get_ptr()`:: +This function is used to retrieve a pointer, _ptr_, to structured data. +The data referenced by _ptr_ 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. + +`nng_socket_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_socket_get_string()`:: +This function is used to retrieve a string into _strp_. +This string is created from the source using `<<nng_strdup.3#,nng_strdup()>>` +and consequently must be freed by the caller using +`<<nng_strfree.3#,nng_strfree()>>` when it is no longer needed. + +`nng_socket_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] +<<nng_dialer_get.3#,nng_dialer_get(3)>>, +<<nng_listener_get.3#,nng_listener_get(3)>>, +<<nng_pipe_get.3#,nng_pipe_get(3)>>, +<<nng_socket_set.3#,nng_socket_set(3)>>, +<<nng_strdup.3#,nng_strdup(3)>>, +<<nng_strerror.3#,nng_strerror(3)>>, +<<nng_strfree.3#,nng_strfree(3)>>, +<<nng_duration.5#,nng_duration(5)>>, +<<nng_options.5#,nng_options(5)>>, +<<nng_socket.5#,nng_socket(5)>>, +<<nng.7#,nng(7)>> |
