General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier f

General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

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1) Unifdef USE_WEAK_SEEDING since it is too obsolete to support and makes
reading hard.

2) Instead of doing range transformation in each and every function here,
do it single time directly in do_ran

1) Unifdef USE_WEAK_SEEDING since it is too obsolete to support and makes
reading hard.

2) Instead of doing range transformation in each and every function here,
do it single time directly in do_rand(). One "mod" operation overhead is not
a big deal, but the code looks nicer and possible future functions additions
or PRNG change do not miss range transformations neither have unneeded ones.

3) Use POSIX argument types for visible functions (cosmetic).

MFC after: 1 week

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libc: do not include <sys/types.h> where <sys/param.h> was already included

According to style(9):
> normally, include <sys/types.h> OR <sys/param.h>, but not both.
(<sys/param.h> already includes <

libc: do not include <sys/types.h> where <sys/param.h> was already included

According to style(9):
> normally, include <sys/types.h> OR <sys/param.h>, but not both.
(<sys/param.h> already includes <sys/types.h> when LOCORE is not defined).

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Use ANSI C prototypes. Eliminates -Wold-style-definition warnings.

Style fix noted by bde@

After fixing ranges restore POSIX requirement: rand() call without
srand() must be the same as srand(1); rand();
(yet one increment)

In addition to prev. commit, for repeated rand_r(3) calls don't forget
to compensate back at the end incremented at the start internal
state.

MFC after: 2 weeks

1) POSIX requires rand(3) return values to be in the [0, RAND_MAX] range,
but ACM formula we use have internal state (and return value) in the
[1, 0x7ffffffe] range, so our RAND_MAX (0x7fffffff) is n

1) POSIX requires rand(3) return values to be in the [0, RAND_MAX] range,
but ACM formula we use have internal state (and return value) in the
[1, 0x7ffffffe] range, so our RAND_MAX (0x7fffffff) is never reached
because it is off by one, zero is not reached too.

Correct both RAND_MAX and rand(3) return value, shifting last one
to the 0 by 1 subtracted, resulting POSIXed [0, 0x7ffffffd(=new RAND_MAX)]
range.

2) Add a checks for not overflowing on too big seeds. It may happens on
the machines, where sizeof(unsigned int) > 32 bits.

Reviewed by: bde [1]
MFC after: 2 weeks

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Renumber clauses to reduce diffs to other versions

NetBSD, OpenBSD, and Android's Bionic number the clauses 1 through 3,
so follow suit to make comparison easier.

Replace access to /dev/random with the kernel pseudo-random number
source sysctl(KERN_ARND) and remove the fallback code.

Obtained from: OpenBSD
Reviewed by: secteam
MFC after: 1 month

Remove undefined behavior from sranddev() and
srandomdev(). This doesn't actually work
with any modern C compiler:

In particular, both clang and modern gcc
verisons silently elide any xor operation

Remove undefined behavior from sranddev() and
srandomdev(). This doesn't actually work
with any modern C compiler:

In particular, both clang and modern gcc
verisons silently elide any xor operation
with 'junk'.

Approved by: secteam
MFC after: 3 days

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libc: Use O_CLOEXEC for various internal file descriptors.

This fixes a race condition where another thread may fork() before CLOEXEC
is set, unintentionally passing the descriptor to the child proc

libc: Use O_CLOEXEC for various internal file descriptors.

This fixes a race condition where another thread may fork() before CLOEXEC
is set, unintentionally passing the descriptor to the child process.

This commit only adds O_CLOEXEC flags to open() or openat() calls where no
fcntl(fd, F_SETFD, FD_CLOEXEC) follows. The separate fcntl() call still
leaves a race window so it should be fixed later.

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Fix typo in the comment

Per Regents of the University of Calfornia letter, remove advertising
clause.

# If I've done so improperly on a file, please let me know.

Back out "drop first N values" method of removing monotonically increased
seed->first value correlation. It breaks rand_r()... Other possible methods
like shuffling inside aray will breaks rand_r() t

Back out "drop first N values" method of removing monotonically increased
seed->first value correlation. It breaks rand_r()... Other possible methods
like shuffling inside aray will breaks rand_r() too, because it assumes
only one word state, i.e. nothing extra can be added after seed assignment
in srand().

BTW, for old formulae seed->first value correlation is not so monotonically
increased as with other Linear Congruential Generators of this type only
becase arithmetic overflow happens. But overflow affects distribution
and lower bits very badly, as many articles says, such type of overflow
not improves PRNG.

So, monotonically increased seed->first value correlation problem remains...

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Since we drop NSHUFF values now, set default seed to what it becomes
after srand(1)

For rand(3) and random(3) TYPE_0 drop NSHUFF values right after srand{om}()
to remove part of seed -> 1st value correlation. Correlation still remains
because of algorithm limits. Note that old algor

For rand(3) and random(3) TYPE_0 drop NSHUFF values right after srand{om}()
to remove part of seed -> 1st value correlation. Correlation still remains
because of algorithm limits. Note that old algorithm have even stronger
correlation, especially in the lower bits area, but not eye-visible, as
current one.

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Park & Miller PRNG can be safely initialized with any value but 0 and stuck
at 0 as designed. Its BSD adaptation tries to fight it by mapping 0 to
2147483647 after calculation, but this method not wo

Park & Miller PRNG can be safely initialized with any value but 0 and stuck
at 0 as designed. Its BSD adaptation tries to fight it by mapping 0 to
2147483647 after calculation, but this method not works since 2147483647
seed returns to 0 again on the next interation. Instead of after calculation
mapping, map 0 to another value _before_ calculation, so it never stucks.

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For some combinations of variable sizes and RAND_MAX value rand_r()
may store less amount bits for seed, than available. Fix it.

Add missing #include "namespace.h".

Fix the style of the SCM ID's.
I believe have made all of libc .c's as consistent as possible.

Add a long-overdue nail to the deprecated /dev/urandom interface
by asking some things that need unpredictable numbers to read
/dev/random instead.

urandom(4) -> random(4) in comments.

PR: 27858
Submitted by: Yoshihiro Koya <[email protected]>
Reviewed by: md5(1)
Approved by: markm

Add #include "un-namespace.h"

srand*dev() fallback code: change ^getpid() to ^(getpid() << 16) to allow
change of high word part too to produce more interesting seed distribution.