Re: bin/51726: sort -n ignored if given after -k

[Abhinav Upadhyay <er.abhinav.upadhyay%gmail.com@localhost>]

On Tue, Dec 20, 2016 at 9:30 PM, Abhinav Upadhyay
<er.abhinav.upadhyay%gmail.com@localhost> wrote:
> On Sun, Dec 18, 2016 at 9:54 PM, Abhinav Upadhyay
> <er.abhinav.upadhyay%gmail.com@localhost> wrote:
>> On Sun, Dec 18, 2016 at 1:55 PM, Robert Elz <kre%munnari.oz.au@localhost> wrote:
>>> The following reply was made to PR bin/51726; it has been noted by GNATS.
>>>
>>> From: Robert Elz <kre%munnari.OZ.AU@localhost>
>>> To: gnats-bugs%NetBSD.org@localhost
>>> Cc:
>>> Subject: Re: bin/51726: sort -n ignored if given after -k
>>> Date: Sun, 18 Dec 2016 15:23:38 +0700
>>>
>>>      Date:        Sun, 18 Dec 2016 02:05:01 +0000 (UTC)
>>>      From:        David Holland <dholland-bugs%netbsd.org@localhost>
>>>      Message-ID:  <20161218020501.468347A302%mollari.NetBSD.org@localhost>
>>>
>>>    |  If you're using -k you're supposed to put the key flags in the -k
>>>    |  argument, that is, sort -k 3nr.
>>>
>>>  Not quite, using global options is still fine, they're just not
>>>  supposed to apply to a key specified if that key has any sort selections
>>>  of its own.
>>>
>>>  Our sort doesn't do that, it merges global options and key specific
>>>  options, in a kind of weird way --- but the behaviour described (while
>>>  perhaps not strictly correct) is I think what is intended.
>>>
>>>  That is, when sorting a key field, you get whatever sort options are
>>>  specified for that key, merged with whatever global options had already
>>>  been given - later global options are supposed to affect the next key
>>>  (or the backup default sort if the keys are equal).   That is, that's how
>>>  the NetBSD sort is written.
>>>
>>>    |  Technically I think if you write -k 3 -n -r and it doesn't honor the
>>>    |  -n it's doing what you asked.
>>>
>>>  According to our sort's design, yes, though I don't think that is posix.
>>>
>>>    | And I think if you write -k 3 -n -r and
>>>    | it *does* sort in reverse order, then *that*'s a bug. sigh.
>>>
>>>  Yes, probably.
>>>
>>>    |  sort's argument handling is a trainwreck.
>>>
>>>  That mild?
>>>
>>>    |  And thus the code in sort that deals with it is horrifying.
>>>
>>>  Yes.   We could probably simplify it a lot if we made it posix
>>>  conformat (where any key specific ordering options disable all
>>>  the globals for that key) but it has been as it is for a long time
>>>  now (mayve even, modulo the k stuff) has been like it since 6th or
>>>  7th edition unix.   So changing it might break a lot - who knows?
>>
>> I have been going over the sort(1) man page from posix, and at one
>> place (in the APPLICATION USAGE section) it says the following about
>> the use of ordering options after -k:
>>
>> "The wording in the OPTIONS section clarifies that the -b, -d, -f, -i,
>> -n, and -r options have to come before the first sort key specified if
>> they are intended to apply to all specified keys. The way it is
>> described in this volume of POSIX.1-2008 matches historical practice,
>> not historical documentation. The results are unspecified if these
>> options are specified after a -k option."
>>
>> So, I guess using `sort -k3 -n -r` is undefined behavior?. That said,
>> the example mentioned in the PR (sort -k 2 -n -r) does work with GNU
>> sort(1). I had a patch ready yesterday, so just posting it here :)
>>
>> This patch lets sort(1) associate -b, -d, -f, -i, -n, -r options to
>> specific fields if specified after -k.  All ATF tests for sort(1) are
>> passing except for a couple of cases in kflag_alpha, but they look
>> ambiguous to me and one of the similar tests is commented out as
>> broken. If we want to accept this behavior in our sort(1) and the
>> patch looks in the right direction, I will try to dig in and get those
>> test cases passing  :)
>>
>> http://www.netbsd.org/~abhinav/sort.c.diff
>

I have a new patch which fixes this issue without breaking any tests,
please have a look:

http://netbsd.org/~abhinav/sort.c.diff_v2

-
Abhinav