MFC 307756: Define max_align_t for C11.

libc++'s stddef.h includes an existing definition of max_align_t for
C++11, but it is only defined for C++, not for C. In addition, GCC and
clang both define an alternate version of max_align_t that uses a
union of multiple types rather than a plain long double as in libc++.
This adds a __max_align_t to <sys/_types.h> that matches the GCC and
clang definition that is mapped to max_align_t in <stddef.h>.

PR: 210890

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Change the cap_rights_t type from uint64_t to a structure that we can extend
in the future in a backward compatible (API and ABI) way.

The cap_rights_t represents capability rights. We used to use one bit to
represent one right, but we are running out of spare bits. Currently the new
structure provides place for 114 rights (so 50 more than the previous
cap_rights_t), but it is possible to grow the structure to hold at least 285
rights, although we can make it even larger if 285 rights won't be enough.

The structure definition looks like this:

struct cap_rights {
uint64_t cr_rights[CAP_RIGHTS_VERSION + 2];
};

The initial CAP_RIGHTS_VERSION is 0.

The top two bits in the first element of the cr_rights[] array contain total
number of elements in the array - 2. This means if those two bits are equal to
0, we have 2 array elements.

The top two bits in all remaining array elements should be 0.
The next five bits in all array elements contain array index. Only one bit is
used and bit position in this five-bits range defines array index. This means
there can be at most five array elements in the future.

To define new right the CAPRIGHT() macro must be used. The macro takes two
arguments - an array index and a bit to set, eg.

#define CAP_PDKILL CAPRIGHT(1, 0x0000000000000800ULL)

We still support aliases that combine few rights, but the rights have to belong
to the same array element, eg:

#define CAP_LOOKUP CAPRIGHT(0, 0x0000000000000400ULL)
#define CAP_FCHMOD CAPRIGHT(0, 0x0000000000002000ULL)

#define CAP_FCHMODAT (CAP_FCHMOD | CAP_LOOKUP)

There is new API to manage the new cap_rights_t structure:

cap_rights_t *cap_rights_init(cap_rights_t *rights, ...);
void cap_rights_set(cap_rights_t *rights, ...);
void cap_rights_clear(cap_rights_t *rights, ...);
bool cap_rights_is_set(const cap_rights_t *rights, ...);

bool cap_rights_is_valid(const cap_rights_t *rights);
void cap_rights_merge(cap_rights_t *dst, const cap_rights_t *src);
void cap_rights_remove(cap_rights_t *dst, const cap_rights_t *src);
bool cap_rights_contains(const cap_rights_t *big, const cap_rights_t *little);

Capability rights to the cap_rights_init(), cap_rights_set(),
cap_rights_clear() and cap_rights_is_set() functions are provided by
separating them with commas, eg:

cap_rights_t rights;

cap_rights_init(&rights, CAP_READ, CAP_WRITE, CAP_FSTAT);

There is no need to terminate the list of rights, as those functions are
actually macros that take care of the termination, eg:

#define cap_rights_set(rights, ...) \
__cap_rights_set((rights), __VA_ARGS__, 0ULL)
void __cap_rights_set(cap_rights_t *rights, ...);

Thanks to using one bit as an array index we can assert in those functions that
there are no two rights belonging to different array elements provided
together. For example this is illegal and will be detected, because CAP_LOOKUP
belongs to element 0 and CAP_PDKILL to element 1:

cap_rights_init(&rights, CAP_LOOKUP | CAP_PDKILL);

Providing several rights that belongs to the same array's element this way is
correct, but is not advised. It should only be used for aliases definition.

This commit also breaks compatibility with some existing Capsicum system calls,
but I see no other way to do that. This should be fine as Capsicum is still
experimental and this change is not going to 9.x.

Sponsored by: The FreeBSD Foundation

Fix <uchar.h> in for C++11.

It turns out that in C++11, char16_t and char32_t are built-in types;
language keywords. Just fix this by putting traditional _*_T_DECLARED
blocks around the definitions. We'll just predefine these in
<sys/_types.h>.

This also opens up the possibility to define char16_t in other header
files, if ever needed (e.g. if we would gain a <ctype.h> for
char16_t/char32_t).

Add <uchar.h>.

The <uchar.h> header, part of C11, adds a small number of utility
functions for 16/32-bit "universal" characters, which may or may not be
UTF-16/32. As our wchar_t is already ISO 10646, simply add light-weight
wrappers around wcrtomb() and mbrtowc().

While there, also add (non-yet-standard) _l functions, similar to the
ones we already have for the other locale-dependent functions.

Reviewed by: theraven

Make the wchar_t type machine dependent.

This is required for ARM EABI. Section 7.1.1 of the Procedure Call for the
ARM Architecture (AAPCS) defines wchar_t as either an unsigned int or an
unsigned short with the former preferred.

Because of this requirement we need to move the definition of __wchar_t to
a machine dependent header. It also cleans up the macros defining the limits
of wchar_t by defining __WCHAR_MIN and __WCHAR_MAX in the same machine
dependent header then using them to define WCHAR_MIN and WCHAR_MAX
respectively.

Discussed with: bde

Define cap_rights_t and DTYPE_CAPABILITY, which are required to
implement Capsicum capabilities.

Approved by: mentor (rwatson), re (bz)

Introduce accmode_t. This is required for NFSv4 ACLs - it will be neccessary
to add more V* constants, and the variables changed by this patch were often
being assigned to mode_t variables, which is 16 bit.

Approved by: rwatson (mentor)

Add cpuset, an api for thread to cpu binding and cpu resource grouping
and assignment.
- Add a reference to a struct cpuset in each thread that is inherited from
the thread that created it.
- Release the reference when the thread is destroyed.
- Add prototypes for syscalls and macros for manipulating cpusets in
sys/cpuset.h
- Add syscalls to create, get, and set new numbered cpusets:
cpuset(), cpuset_{get,set}id()
- Add syscalls for getting and setting affinity masks for cpusets or
individual threads: cpuid_{get,set}affinity()
- Add types for the 'level' and 'which' parameters for the cpuset. This
will permit expansion of the api to cover cpu masks for other objects
identifiable with an id_t integer. For example, IRQs and Jails may be
coming soon.
- The root set 0 contains all valid cpus. All thread initially belong to
cpuset 1. This permits migrating all threads off of certain cpus to
reserve them for special applications.

Sponsored by: Nokia
Discussed with: arch, rwatson, brooks, davidxu, deischen
Reviewed by: antoine

Let kernel POSIX timer code and mqueue code to use integer as a resource
handle, the timer_t and mqd_t types will be a pointer which userland
will define it.

Bring in experimental kernel support for POSIX message queue.

- Declare mknod in stat.h (in addition to unistd.h), as per XSI.
- Use blksize_t and blkcnt_t in struct stat.
- Hide non-standard fields in stat.h when !__BSD_VISIBLE.
- Add restrict qualifiers in stat.h.

Document why rlim_t needs to be a signed type.
Define RLIM_INFINITY as INT64_MAX instead of hand-rolling it.

MFC after: 1 week

Define __lwpid_t as an int32_t in <sys/_types.h> and define lwpid_t
as an __lwpid_t in <sys/types.h>. Retype td_tid from an int to a
lwpid_t and change related definitions accordingly.

Second half of the dev_t cleanup.

The big lines are:
NODEV -> NULL
NOUDEV -> NODEV
udev_t -> dev_t
udev2dev() -> findcdev()

Various minor adjustments including handling of userland access to kernel
space struct cdev etc.

Do the dreaded s/dev_t/struct cdev */
Bump __FreeBSD_version accordingly.

Fixed some style bugs:
- the comments on the rune/wide char types were lost
- struct cdev was bogusly forward declared
- some comments were excessively indented.

Add __fixpt_t to _types.h, and typedef __fixpt_t fixpt_t in types.h.

Move details of dev_t (and udev_t) to <sys/_types.h>.

Share ino_t and nlink_t.

Add suseconds_t and useconds_t for storing microseconds.

Note that id_t can also hold a gid_t. Realign comments.

Add id_t, a new type capable of representing a pid_t or a uid_t. Move
the definition of rlim_t to <sys/_types.h> so that it can be shared.

Move details of key_t to <sys/_types.h>, so that it can be typedef'd
in more than just <sys/types.h>.

Move definition of nl_item type to <sys/_types.h>, so that it can be
shared.

Move intrmask_t to the kernel-only section of <sys/types.h>. Add some
comments submitted by bde.

o Fix namespace issues in <sys/mman.h>.
o Move mode_t details from <sys/types.h> into <sys/_types.h>.
o Add primitives for sharing the mode_t and off_t typedefs.
o Add typedefs mode_t, off_t, and size_t to <sys/mman.h>.

PR: 21644

Move several MI types from <machine/_types.h> to <sys/_types.h>.
These types are unlikely to ever become very MD. They include:
clockid_t, ct_rune_t, fflags_t, intrmask_t, mbstate_t, off_t, pid_t,
rune_t, socklen_t, timer_t, wchar_t, and wint_t.

While moving them, make a few adjustments (submitted by bde):
o __ct_rune_t needs to be precisely `int', not necessarily __int32_t,
since the arg type of the ctype functions is int.
o __rune_t, __wchar_t and __wint_t inherit this via a typedef of
__ct_rune_t.
o Some minor wording changes in the comment blocks for ct_rune_t and
mbstate_t.

Submitted by: bde (partially)

o Merge <machine/ansi.h> and <machine/types.h> into a new header
called <machine/_types.h>.
o <machine/ansi.h> will continue to live so it can define MD clock
macros, which are only MD because of gratuitous differences between
architectures.
o Change all headers to make use of this. This mainly involves
changing:
#ifdef _BSD_FOO_T_
typedef _BSD_FOO_T_ foo_t;
#undef _BSD_FOO_T_
#endif
to:
#ifndef _FOO_T_DECLARED
typedef __foo_t foo_t;
#define _FOO_T_DECLARED
#endif

Concept by: bde
Reviewed by: jake, obrien

Implement the <sys/statvfs.h> header. Related changes to <sys/types.h>
are still awaiting a worldstone. Functions and their declarations to
come later.

Add sa_family_t type to <sys/_types.h> and typedefs to <netinet/in.h>
and <sys/socket.h>. Previously, sa_family_t was only typedef'd in
<sys/socket.h>.

o Implement <sys/_types.h>, a new header for storing types that are
MI, not required to be a fixed size, and used in multiple headers.
This will grow in time, as more things move here from <sys/types.h>
and <machine/ansi.h>.
o Add missing type definitions (uint16_t and uint32_t) to
<arpa/inet.h> and <netinet/in.h>.
o Reduce pollution in <sys/types.h> by using `#if _FOO_T_DECLARED'
widgets to avoid including <sys/stdint.h>.
o Add some missing type definitions to <unistd.h> and note the ones
that still need to be added.
o Make use of <sys/_types.h> primitives in <grp.h> and <sys/types.h>.

Reviewed by: bde