MFC r337983, r338044:
Add pthread_get_name_np(3).

Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

MFC r315526

Add clock_nanosleep()

Add a clock_nanosleep() syscall, as specified by POSIX.
Make nanosleep() a wrapper around it.

Attach the clock_nanosleep test from NetBSD. Adjust it for the
FreeBSD behavior of updating rmtp only when interrupted by a signal.
I believe this to be POSIX-compliant, since POSIX mentions the rmtp
parameter only in the paragraph about EINTR. This is also what
Linux does. (NetBSD updates rmtp unconditionally.)

Copy the whole nanosleep.2 man page from NetBSD because it is complete
and closely resembles the POSIX description. Edit, polish, and reword it
a bit, being sure to keep any relevant text from the FreeBSD page.

Regenerate syscall files.

Relnotes: yes
Sponsored by: Dell EMC

MFC r314179 r314206 r314424

Add sem_clockwait_np()

This function allows the caller to specify the reference clock
and choose between absolute and relative mode. In relative mode,
the remaining time can be returned.

The API is similar to clock_nanosleep(3). Thanks to Ed Schouten
for that suggestion.

While I'm here, reduce the sleep time in the semaphore "child"
test to greatly reduce its runtime. Also add a reasonable timeout.

Relnotes: yes
Sponsored by: Dell EMC

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Add implementations of sendmmsg(3) and recvmmsg(3) functions which
wraps sendmsg(2) and recvmsg(2) into batch send and receive operation.
The goal of this implementation is only to provide API compatibility
with Linux.

The cancellation behaviour of the functions is not quite right, but
due to relative rare use of cancellation it is considered acceptable
comparing with the complexity of the correct implementation. If
functions are reimplemented as syscalls, the fix would come almost
trivial. The direct use of the syscall trampolines instead of libc
wrappers for sendmsg(2) and recvmsg(2) is to avoid data loss on
cancellation.

Submitted by: Boris Astardzhiev <boris.astardzhiev@gmail.com>
Discussed with: jilles (cancellation behaviour)
MFC after: 1 month

Implement the waitid() SUSv4 function using wait6() system call.

PR: standards/170346
Submitted by: "Jukka A. Ukkonen" <jau@iki.fi>
MFC after: 1 month

Introduce a non-portable function pthread_getthreadid_np(3) to retrieve
calling thread's unique integral ID, which is similar to AIX function of
the same name. Bump __FreeBSD_version to note its introduction.

Reviewed by: kib

Revert revision 214007, I realized that MySQL wants to resolve
a silly rwlock deadlock problem, the deadlock is caused by writer
waiters, if a thread has already locked a reader lock, and wants to
acquire another reader lock, it will be blocked by writer waiters,
but we had already fixed it years ago.

Unbreak buildworld by including pthread_rwlockattr_setkind_np and
pthread_rwlockattr_getkind_np.

Make openat(2) a cancellation point.

This is required by POSIX and matches open(2).

Reviewed by: kib, jhb
MFC after: 1 month

Make pthread_cleanup_push() and pthread_cleanup_pop() as a pair of macros,
use stack space to keep cleanup information, this eliminates overhead of
calling malloc() and free() in thread library.

Discussed on: thread@

Add pthread_setaffinity_np and pthread_getaffinity_np to libc namespace.

Compile libthr with warnings.

Add pthread_mutex_isowned_np() so there is no need for an additional
prototype next to the implementation.

MFC after: 2 weeks

Add semaphore functions, and remove some dupes from the #if 0 section.

Add a bunch of missing pthread functions, and move out-of-order functions.

Add entries for new pthread stubs.

Add namespace #defines for usleep.

Back out the `hiding' of strlcpy and strlcat. Several people
vocally objected to this safety belt.

`Hide' strlcpy and strlcat (using the namespace.h / __weak_reference
technique) so that we don't wind up calling into an application's
version if the application defines them.

Inspired by: qpopper's interfering and buggy version of strlcpy

= Implement name service switch modules (NSS modules). NSS modules
may be built into libc (`static NSS modules') or dynamically loaded
via dlopen (`dynamic NSS modules'). Modules are loaded/initialized
at configuration time (i.e. when nsdispatch is called and nsswitch.conf
is read or re-read).

= Make the nsdispatch(3) core thread-safe.

= New status code for nsdispatch(3) `NS_RETURN', currently used to
signal ERANGE-type issues.

= syslog(3) problems, don't warn/err/abort.

= Try harder to avoid namespace pollution.

= Implement some shims to assist in porting NSS modules written for
the GNU C Library nsswitch interface.

Sponsored by: DARPA, Network Associates Laboratories

Eliminate 61 warnings emitted at WARNS=2 (leaving 53 to go).
Only warnings that could be fixed without changing the generated object
code and without restructuring the source code have been handled.

Reviewed by: /sbin/md5

Add waitpid to the list of hidden names for use by wordexp.c and grantpt.c.

Use a jump table (a la Solaris) for pthread routines with default
entries in the table being stubs. While I'm here, add macros to
auto-generate the stubs. A conforming threads library can override
the stub routines by filling in the jump table.

Add some entries to namespace.h and sync un-namespace.h to it.
Also add a comment to remind folks to update un-namespace.h
when changing namespace.h.

Do not use __progname directly (except in [gs]etprogname(3)).
Also, make an internal _getprogname() that is used only inside
libc. For libc, getprogname(3) is a weak symbol in case a
function of the same name is defined in userland.

Fixed namespace pollution related to `err' in libc in the same way as for
`warn'. Now a whole 2 members of the err() family don't cause pollution.

This fixes world breakage in awk for NOSHARED worlds. contrib/awk/msg.c
has had its own version of err() for a long time, but this somehow
didn't cause problems until the update to awk-3.1.0.

signanosleep(2) hasn't existed since 1998.

Fixed namespace pollution related to `warn' in libc (but not in other
libraries or for other members of the err() family).

This fixes world breakage in bc and rcs/* for NOSHARED worlds.

Add entries for the posix1e functions that will be overridden in libc_r.

Approved by: rwatson
Obtained from: TrustedBSD Project

libc MT-safety, part 2.

Add a lock to FILE. flockfile and friends are now implemented
(for the most part) in libc. flockfile_debug is implemented in
libc_r; I suppose it's about time to kill it but will do it in
a future commit.

Fix a potential deadlock in _fwalk in a threaded environment.
A file flag (__SIGN) was added to stdio.h that, when set, tells
_fwalk to ignore it in its walk. This seemed to be needed in
refill.c because each file needs to be locked when flushing.

Add a stub for pthread_self in libc. This is needed by flockfile
which is allowed by POSIX to be recursive.

Make fgetpos() error return value (-1) match man page.

Remove recursive calls to locked functions (stdio); I think I've
got them all, but I may have missed a couple.

A few K&R -> ANSI conversions along with removal of a few instances
of "register".

$Id$ -> $FreeBSD$ in libc/stdio/rget.c

Not objected to: -arch, a few months ago

Remove _THREAD_SAFE and make libc thread-safe by default by
adding (weak definitions to) stubs for some of the pthread
functions. If the threads library is linked in, the real
pthread functions will pulled in.

Use the following convention for system calls wrapped by the
threads library:
__sys_foo - actual system call
_foo - weak definition to __sys_foo
foo - weak definition to __sys_foo

Change all libc uses of system calls wrapped by the threads
library from foo to _foo. In order to define the prototypes
for _foo(), we introduce namespace.h and un-namespace.h
(suggested by bde). All files that need to reference these
system calls, should include namespace.h before any standard
includes, then include un-namespace.h after the standard
includes and before any local includes. <db.h> is an exception
and shouldn't be included in between namespace.h and
un-namespace.h namespace.h will define foo to _foo, and
un-namespace.h will undefine foo.

Try to eliminate some of the recursive calls to MT-safe
functions in libc/stdio in preparation for adding a mutex
to FILE. We have recursive mutexes, but would like to avoid
using them if possible.

Remove uneeded includes of <errno.h> from a few files.

Add $FreeBSD$ to a few files in order to pass commitprep.

Approved by: -arch