Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Fixed missing or broken library dependencies.

Fixed error checking of pthread(3) functions.

PR: 143807
Submitted by: pluknet (partly)

Add a new 'void closefrom(int lowfd)' system call. When called, it closes
any open file descriptors >= 'lowfd'. It is largely identical to the same
function on other operating systems such as Solaris, DFly, NetBSD, and
OpenBSD. One difference from other *BSD is that this closefrom() does not
fail with any errors. In practice, while the manpages for NetBSD and
OpenBSD claim that they return EINTR, they ignore internal errors from
close() and never return EINTR. DFly does return EINTR, but for the common
use case (closing fd's prior to execve()), the caller really wants all
fd's closed and returning EINTR just forces callers to call closefrom() in
a loop until it stops failing.

Note that this implementation of closefrom(2) does not make any effort to
resolve userland races with open(2) in other threads. As such, it is not
multithread safe.

Submitted by: rwatson (initial version)
Reviewed by: rwatson
MFC after: 2 weeks

Add a regression test for multiple threads of the same process acquiring the same fcntl lock.

Approved by: dfr (mentor)

Add a regresion test to determine whether or not a file descriptor is
allocated in a fork(2)-inheritable way at the beginning or end of an
accept(2) system call. This test creates a test thread and blocks it
in accept(2), then forks a child process which tests to see if the
next available file descriptor is defined or not (EBADF vs EINVAL for
ftruncate(2)).

This detects a regression introduced during the network stack locking
work, in which a very narrow race during which fork(2) from one
thread during accept(2) in a second thread lead to an extra inherited
file descriptor turned into a very wide race ensuring that a
descriptor was leaked into the child even though it hadn't been
returned.

PR: kern/130348

Re-implement the client side of rpc.lockd in the kernel. This implementation
provides the correct semantics for flock(2) style locks which are used by the
lockf(1) command line tool and the pidfile(3) library. It also implements
recovery from server restarts and ensures that dirty cache blocks are written
to the server before obtaining locks (allowing multiple clients to use file
locking to safely share data).

Sponsored by: Isilon Systems
PR: 94256
MFC after: 2 weeks

Fix the __FreeBSD_version check.

Add some regression tests for posix record locks.

Introduce a new F_DUP2FD command to fcntl(2), for compatibility with
Solaris and AIX.
fcntl(fd, F_DUP2FD, arg) and dup2(fd, arg) are functionnaly equivalent.
Document it.
Add some regression tests (identical to the dup2(2) regression tests).

PR: 120233
Submitted by: Jukka Ukkonen
Approved by: rwaston (mentor)
MFC after: 1 month

o Indent by tab.

o Add several regression tests for dup(2), dup2(2) and fcntl(F_DUPFD).

Obtained from: OpenBSD

o style.Makefile(5): WARNS= -> WARNS?=.

When extending a file with truncate, check that newly added bytes have
a value of 0 in the extended region.

Make sure that we get EINVAL back if we try to truncate a read-only
file descriptor.

Add regression tests to make sure that attempting to call ftruncate() on
various non-file objects fails.

Add very basic ftruncate() regression test, with a comment rather more
thorough than the tests regarding what should be tested.