MFC r327317:

humanize_number(3): fix math edge case in rounding large numbers

Fix for remainder overflow, when in rare cases adding remainder to divider
exceeded 1 and turned the total to 1000 in final formatting, taking up
the space for the unit character.

The fix continues the division of the original number if the above case
happens -- added the appropriate check to the for loop performing
the division. This lowers the value shown, to make it fit into the buffer
space provided (1.0M for 4+1 character buffer, as used by ls).

Add test case for the reported bug and extend test program to support
providing buffer length (ls -lh uses 5, tests hard-coded 4).

PR: 224498

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

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

don't assert on bad args, instead return an error..

Since so many programs don't check return value, always NUL terminate
the buf...

fix rounding when using base 1024 (the bug that started it all)...

add a set of test cases so we can make sure that things don't break
in the future...

Thanks to Clifton Royston for testing and the test program...

Approved by: re (hrs, glebius)
MFC after: 1 week

Add support for IEE/IEC (and now also SI) power of two notions of
prefixes (Ki, Mi, Gi...) for humanize_number(3).

Note that applications has to pass HN_IEC_PREFIXES to use this
feature for backward compatibility reasons.

Reviewed by: arundel
MFC after: 2 weeks

s/buffer/buf as is used in the code.

Submitted by: arundel (via doc@)
MFC after: 3 days

The NetBSD Foundation has granted permission to remove clause 3 and 4 from
their software.

Obtained from: NetBSD

Adjust history.

Approved by: re(ken)

Point expand_number(3) at humanize_number(3) and nive versa.

Suggested by: trhodes
Approved by: re (kensmith)

Markup fixes.

Note the convention that humanize_number follows.
Add 'engineering' numbers to table.

Remove duplicated "bytes".

Submitted by: Wojciech A. Koszek [dunstan freebsd czest pl]
PR: 79747

Backout manual page updates.

Requested by: ru

Take the lastest fixes from NetBSD.

Obtained from: NetBSD

There is no such manual page in FreeBSD.

Markup fixes.

Humanize_number(3) is a part of libutil.

You want to include libutil.h, not util.h.
Some minor sentence tweaking.

Add humanize_number(3) to libutil for formating numbers into a human
readable form.

Obtained from: NetBSD