sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

namespace nv names, version libnv and libnvpair library symbols

libnv and libnvpair have aliased symbols, and as a result a single process which
dlopens a shared object that is dynamically linked to libnv and another to
libnvpair will wind up with a single set of resolved symbols for those in
conflict. A source file also cannot include both libnv and libnvpair headers
because of aliased identifiers. To resolve the situation, libnv types and
functions are namespaced via nv_namespace.h, and libnv symbols are
versioned. The msgio functions are not namespaced or exported as they are not
part of the external API.

Reviewed by: kevans
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D35261

libnv: Add nvlist_append_*_array() family of functions.

The nvlist_append_{bool,number,string,nvlist,descriptor}_array() functions
allows to dynamically extend array stored in the nvlist.

Submitted by: Mindaugas Rasiukevicius <rmind@netbsd.org>

SPDX: mostly fixes to previous changes.

Introduce the recently approved BSD-1-Clause and replace 0BSD which
never did fit well our use cases.

Allow libnv to be built externally using GCC.

GCC does not define _VA_LIST_DECLARED. It defines _VA_LIST_ and others.
This was causing the prototype to not be defined and leading to an error
later due to using nvlist_add_stringv(3) without a prototype in
nvlist_add_stringf(3).

This uses the same check as other va_list prototypes in the original
change in r279438.

Add support for the arrays in nvlist library.

- Add
nvlist_{add,get,take,move,exists,free}_{number,bool,string,nvlist,
descriptor} functions.
- Add support for (un)packing arrays.
- Add the nvl_array_next field to the nvlist structure.
If an array is added by the nvlist_{move,add}_nvlist_array function
this field will contains next element in the array.
- Add the nitems field to the nvpair and nvpair_header structure.
This field contains number of elements in the array.
- Add special flag (NV_FLAG_IN_ARRAY) which is set if nvlist is a part of
an array.
- Add special type (NV_TYPE_NVLIST_ARRAY_NEXT).This type is used only
on packing/unpacking.
- Add new API for traversing arrays (nvlist_get_array_next).
- Add the nvlist_get_pararr function which combines the
nvlist_get_array_next and nvlist_get_parent functions. If nvlist is in
the array it will return next element from array. If nvlist is last
element in array or it isn't in array it will return his
container (parent). This function should simplify traveling over nvlist.
- Add tests for new features.
- Add documentation for new functions.
- Add my copyright.
- Regenerate the sys/cddl/compat/opensolaris/sys/nvpair.h file.

PR: 191083
Reviewed by: allanjude (doc)
Approved by: pjd (mentor)

Introduce the NV_FLAG_NO_UNIQUE flag. When set, it allows to store
multiple values using the same key in a nvlist.

Approved by: pjd (mentor)
Obtained from: WHEEL Systems (http://www.wheelsystems.com)

Update man page.

Reviewed by: AllanJude
Approved by: pjd (mentor)

Approved, oprócz użycie RESTORE_ERRNO() do ustawiania errno.

Change the nvlist_recv() function to take additional argument that
specifies flags expected on the received nvlist. Receiving a nvlist with
different set of flags than the ones we expect might lead to undefined
behaviour, which might be potentially dangerous.

Update consumers of this and related functions and update the tests.

Approved by: pjd (mentor)

Update man page for nvlist_unpack, nvlist_recv, nvlist_xfer, cap_recv_nvlist
and cap_xfer_nvlist.

Reviewed by: AllanJude
Approved by: pjd (mentor)

Add nvlist_flags() function, which returns nvlist's public flags.

Approved by: pjd (mentor)

Remove the nvlist_.*[fv] functions.

Those functions are problematic, because there is no way to report
memory allocation problems without complicating the API, so we can
either abort or potentially return invalid results. None of which is
acceptable.

In most cases the caller knows the size of the name, so he can allocate
buffer on the stack and use snprintf(3) to prepare the name.

After some discussion the conclusion is to removed those functions,
which also simplifies the API.

Discussed with: pjd, rstone
Approved by: pjd (mentor)

Move libnv into the kernel and hook it into the kernel build

Differential Revision: https://reviews.freebsd.org/D1883
Reviewed by: jfv
MFC after: 1 month
Sponsored by: Sandvine Inc.