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CNV(9) FreeBSD Kernel Developer's Manual CNV(9)
NAME
cnvlist_get, cnvlist_take, cnvlist_free - API for managing name/value
pairs by cookie.
LIBRARY
Name/value pairs library (libnv, -lnv)
SYNOPSIS
#include <sys/cnv.h>
const char *
cnvlist_name(const void *cookie);
int
cnvlist_type(const void *cookie);
bool
cnvlist_get_bool(const void *cookie);
uint64_t
cnvlist_get_number(const void *cookie);
const char *
cnvlist_get_string(const void *cookie);
const nvlist_t *
cnvlist_get_nvlist(const void *cookie);
const void *
cnvlist_get_binary(const void *cookie, size_t *sizep);
const bool *
cnvlist_get_bool_array(const void *cookie, size_t *nitemsp);
const uint64_t *
cnvlist_get_number_array(const void *cookie, size_t *nitemsp);
const char * const *
cnvlist_get_string_array(const void *cookie, size_t *nitemsp);
const nvlist_t * const *
cnvlist_get_nvlist_array(const void *cookie, size_t *nitemsp);
int
cnvlist_get_descriptor(const void *cookie);
const int *
cnvlist_get_descriptor_array(const void *cookie, size_t *nitemsp);
bool
cnvlist_take_bool(void *cookie);
uint64_t
cnvlist_take_number(void *cookie);
const char *
cnvlist_take_string(void *cookie);
const bool *
cnvlist_take_bool_array(void *cookie, size_t *nitemsp);
const uint64_t *
cnvlist_take_number_array(void *cookie, size_t *nitemsp);
const char * const *
cnvlist_take_string_array(void *cookie, size_t *nitemsp);
const nvlist_t * const *
cnvlist_take_nvlist_array(void *cookie, size_t *nitemsp);
int
cnvlist_take_descriptor(void *cookie);
const int *
cnvlist_take_descriptor_array(void *cookie, size_t *nitemsp);
void
cnvlist_free_null(void *cookie);
void
cnvlist_free_bool(void *cookie);
void
cnvlist_free_number(void *cookie);
void
cnvlist_free_string(void *cookie);
void
cnvlist_free_nvlist(void *cookie);
void
cnvlist_free_descriptor(void *cookie);
void
cnvlist_free_binary(void *cookie);
void
cnvlist_free_bool_array(void *cookie);
void
cnvlist_free_number_array(void *cookie);
void
cnvlist_free_string_array(void *cookie);
void
cnvlist_free_nvlist_array(void *cookie);
void
cnvlist_free_descriptor_array(void *cookie);
DESCRIPTION
The libnv library permits easy management of name/value pairs and can
send and receive them over sockets. For more information, also see
nv(9).
with the given cookie. Types which can be returned are described in
nv(9).
The cnvlist_get family of functions obtains the value associated with the
given cookie. Returned strings, nvlists, descriptors, binaries, or
arrays must not be modified by the user, since they still belong to the
nvlist. The nvlist must not be in an error state.
The cnvlist_take family of functions returns the value associated with
the given cookie and removes the element from the nvlist. When the value
is a string, binary, or array value, the caller is responsible for
freeing the returned memory with free(3). When the value is an nvlist,
the caller is responsible for destroying the returned nvlist with
nvlist_destroy(). When the value is a descriptor, the caller is
responsible for closing the returned descriptor with the close(2).
The cnvlist_free family of functions removes an element of the supplied
cookie and frees all resources. If an element of the given cookie has
the wrong type or does not exist, the program is aborted.
EXAMPLES
The following example demonstrates how to deal with cnvlist API.
int type;
void *cookie, *scookie, *bcookie;
nvlist_t *nvl;
char *name;
nvl = nvlist_create(0);
nvlist_add_bool(nvl, "test", 1 == 2);
nvlist_add_string(nvl, "test2", "cnvlist");
cookie = NULL;
while (nvlist_next(nvl, &type, &cookie) != NULL) {
switch (type) {
case NV_TYPE_BOOL:
printf("test: %d\n", cnvlist_get_bool(cookie));
bcookie = cookie;
break;
case NV_TYPE_STRING:
printf("test2: %s\n", cnvlist_get_string(cookie));
scookie = cookie;
break;
}
}
name = cnvlist_take_string(scookie);
cnvlist_free_bool(bcookie);
printf("test2: %s\n", name);
free(name);
printf("nvlist_empty = %d\n", nvlist_empty(nvl));
nvlist_destroy(nvl);
return (0);
SEE ALSO
close(2), free(3), nv(9)