Add a -D option to touch, which acts like the -d option added to
chmod/chown/chgrp (probably others) in the not too far distant past,
and causes the operation to be a no-op if no actual change would be
made (avoiding updating the file's ctime for no reason).

That is, with touch, -D causes no modifying sys call to be made to
a file if that file's atime and mtime are already set to the values
that would be used. A common case for this is when a "-r ref-file"
is also a target file for the operation.

Unfortunately -d was already taken in touch, so next best available is -D.

Add a -R option, which is identical to -r, except that if the reference file
is a symbolic link, the times to use are taken from those of the symbolic
link itself, instead of from the file it references. If the reference file
is not a symbolic link, -R and -r are identical.

This allows the BUGS entry in the manual page to be removed.

Check that mktime() (or timegm() the one time it is used) do not
alter any of the material fields of the struct tm that was handed
to it. If any were altered, then the time string passed in was
not a valid time representation, and so should be rejected.

This one is not an invisible change, it prevents use of things like
"-t 202402300000" (which previously would have been interpreted as
"-t 202403010000" - the day after the 29th of Feb in 2024).

I believe this is an improvement however, and in line with the
general intent that if you specify a date and time, that exact
date and time is what touch should be using. It does mean that
specifying "60" for the seconds field is almost guaranteed to
fail on any POSIX system, as leap seconds simply don't exist
there (on a non-POSIX-conforming system that uses leap seconds,
the :60 should work, if specified with the correct date and time
at which the leap second actually occurs).

The one exception is when parsedate(3) is used, as that does not
do this check (which allows things like "-1 day" on the 1st of
a month to work).

(This is the last of this sequence of updates to touch.c, an
update to touch.1 follows).

Properly implement the POSIX format -d option.

Previously we have hacked that using parsedate(3) - but parsedate()
returns a time_t and consequently while it "handles" fractional seconds,
all that meant (all it really can mean) is that they're ignored.

The POSIX spec expects that (at least if the filesystem supports them)
fractional seconds can be set using the -d option.

Handle that by first attempting to parse the -d arg as a posix format
date-time string (using a reasonably strict parser), and if that fails,
then fall back on parsedate(3) to parse the arg.

If the posix format parse succeeds, the result will be the same as
parsedate(3) would return for the same string - except any fractional
seconds will be handled properly. If it fails, then nothing changes
from what we currently do.

Note the POSIX string is
YYYY-MM-DDThh:mm:ss[.frac][Z]
where YYYY is (at least) 4 digits (leading 0's are acceptable if
you really must!) all the MM DD hh mm ss fields are exactly 2
digits, T is either 'T' or ' ', '.' is either itself, or ',',
and 'frac' is one or more digits. Z (if given) is 'Z'. The
[.,]frac and Z fields are optional. Specify a time in a
slight shorthand like 2024-2-8T7:44:20 and the POSIX parse
will fail, leaving parsedate() to handle that (which it should).
But any fractional seconds which were given would be ignored.

Doc update coming - note the doc will call the YYYY field CCYY
instead, that's just a convenience to make other parts of what
is there make more sense - it is still one 4 (or more) digit field.

This should be an almost invisible change.

Sprinkle come const - but not too much of a good thing.

NFCI

Parameterise the "if year < 69 it is 20xx and if >=69 it is 19xx" rule
to make it simpler to (eventually, many years hence) to change that rule
to be "if year is < NN it is 21xx and if >= NN it is 20xx" instead.

Avoid comparing a time_t to -1 directly, as time_t might be unsigned.
Instead define NO_TIME as ((time_t)-1) and compare with that instead.
This makes no difference at all when time_t is signed (as it is on
NetBSD).

Use "ss" rather than "SS" as the seconds indicators (in messages)
to match with hh (hours) and mm (minutes) rather than looking like
some relation to YY (year) MM (month) and DD (day). Why this was
ever written as SS is beyond me, but it has been that way forever.
(doc update will follow).

Minor improvement to the error message if the arg to a -t option
is unable to be parsed correctly.

NMFCI (No meaningful...)

KNF (space after keyword, and 80 column police).

NFCI

(This is the first of a series of changes to be committed
in rapid sequence).

Don't truncate at microseconds while preserving timestamps.

One of motivation of this change is to make the behavior of test(1)
-nt/ot with preserved copy (like cp -p) closer to the NetBSD 6.
Of course whether full timestamps are kept or not depends also on
underlying file system.

The ifdef added in mv(1) since existing ifdefs was our local change
to compile it on solaris (though I couldn't test it):
http://mail-index.netbsd.org/tech-userlevel/2014/11/28/msg008831.html

branches: 1.32.8; 1.32.10;
Recognize --date and --reference like gnu.

branches: 1.31.2;
add an option to parse human dates.

branches: 1.30.2;
ANSIfy, static + __dead

-f no longer has effect. from Snader_LB on irc.

branches: 1.28.2;
remove read-write code because it's dangerous.
there's no point to try this hard anyway.

branches: 1.27.6;
Remove the \n and tabs from the __COPYRIGHT() strings.
Tweak to use a consistent format.

branches: 1.26.22;
Coverty 1212: Avoid close(-1).

Fix more FALLTHOUGH -> FALLTHROUGH typo.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22365, verified by myself.

branches: 1.23.2;
Nit: In the compatibility case, set the seconds to 0.

branches: 1.22.4;
Add { and } to shut up egcs. Reformat the more questionable code.

Fix the old-style date parsing code as well.

Minor code rearrangement, and allow less of the time stamp to be specified.

Pull in tzfile.h.

Use TM_YEAR_BASE to adjust tm_year, not 1900.

Revert to previous version; new libc function "versioning" works
with the original.

Make this work with the new versioned stat(2) functions.

branches: 1.15.2;
WARNSify, fix .Nm usage, getopt returns -1 not EOF

Purely cosmetic change.

Add h option to usage.

Introduce new flag, -h, to manupilate access/modification time of
symbolic link.

Sync with 44lite2

can't assume that timeval.ts_sec is same type as time_t. grr.

Merged with 4.4lite.
Changed to conform to NetBSD's new RCS Id convention.

Localization changes + minor bug fix.

fix for "touch -t CCYYMMDDhhmm[.SS]". the CC part didn't work. from
Thomas Eberhardt <thomas@mathematik.uni-Bremen.de>

Add 4.4-specific code in `#ifdef notyet's.

Add RCS identifiers.

fix bug in touch's non-posix compatibility support. bug report also
forwarded to CSRG as this is their current 'touch'. bug reported by
Kim Andersen <kim@dde.dk>

s/__dead/volatile/

new touch

branches: 1.1.1;
Initial revision