src/lib/libc/stdlib/rand.c, branch releng/12.4

General further adoption of SPDX licensing ID tags.

2017-11-20T19:49:47Z

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.

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

2016-05-29T13:57:06Z

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

libc: do not include where was already included

2016-04-18T21:05:15Z

According to style(9): > normally, include OR , but not both. ( already includes when LOCORE is not defined).

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

2015-09-20T20:24:28Z

Style fix noted by bde@

2013-07-04T12:35:39Z

After fixing ranges restore POSIX requirement: rand() call without

2013-07-04T00:02:10Z

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

2013-07-03T23:27:04Z

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,

2013-07-03T21:21:54Z

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

Renumber clauses to reduce diffs to other versions

2013-06-13T00:19:30Z

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

2013-04-02T23:41:20Z

source sysctl(KERN_ARND) and remove the fallback code. Obtained from: OpenBSD Reviewed by: secteam MFC after: 1 month