GNU bug report logs - #44889
[PATCH] rm: do not skip extra files when removal of empty directories fails

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Nishant Nayan <nishant.nayan <at> oracle.com>
Subject: bug#44883: closed (Re: bug#44889: [PATCH] rm: do not skip extra
 files when removal of empty directories fails)
Date: Thu, 26 Nov 2020 19:41:02 +0000

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Your bug report

#44889: "rm -rf *" performs an extra skip when it encounters an immutable empty directory

which was filed against the coreutils package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 44883 <at> debbugs.gnu.org.

-- 
44889: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=44889
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Pádraig Brady <P <at> draigBrady.com>
To: Nick Alcock <nick.alcock <at> oracle.com>
Cc: elena.zannoni <at> oracle.com, nishant.nayan <at> oracle.com, bert.barbe <at> oracle.com,
 44889-done <at> debbugs.gnu.org, jemarch <at> gnu.org
Subject: Re: bug#44889: [PATCH] rm: do not skip extra files when removal of
 empty directories fails
Date: Thu, 26 Nov 2020 19:39:54 +0000

On 26/11/2020 18:49, Nick Alcock wrote:
> On 26 Nov 2020, Pádraig Brady verbalised:
> 
>> On 26/11/2020 14:35, Nick Alcock wrote:
>>> diff --git a/src/remove.c b/src/remove.c
>>> index 2d40c55cd..1150cf179 100644
>>> --- a/src/remove.c
>>> +++ b/src/remove.c
>>> @@ -508,8 +508,7 @@ rm_fts (FTS *fts, FTSENT *ent, struct rm_options const *x)
>>>                s = excise (fts, ent, x, true);
>>>                fts_skip_tree (fts, ent);
>>>              }
>>> -
>>> -        if (s != RM_OK)
>>> +        else if (s != RM_OK)
>>>              {
>>>                mark_ancestor_dirs (ent);
>>>                fts_skip_tree (fts, ent);
>>
>> I think we'd still like to mark ancestors when failing to remove,
>> so that we don't prompt unnecessarily.
> 
> If this doesn't make the test fail, I'm fine with it.

Cool, the test still passes :)

>> I think it would be better to do:
>>
>> diff --git a/src/remove.c b/src/remove.c
>> index 2d40c55cd..adf948935 100644
>> --- a/src/remove.c
>> +++ b/src/remove.c
>> @@ -506,7 +506,8 @@ rm_fts (FTS *fts, FTSENT *ent, struct rm_options const *x)
>>               /* When we know (from prompt when in interactive mode)
>>                  that this is an empty directory, don't prompt twice.  */
>>               s = excise (fts, ent, x, true);
>> -            fts_skip_tree (fts, ent);
>> +            if (s == RM_OK)
>> +              fts_skip_tree (fts, ent);
>>             }
> 
> I don't really understand what mark_ancestor_dirs is doing, but as long
> as it's not making the file disappear and the new test still passes I'm
> fine with this (though honestly the s= stuff is incredibly confusing and
> really should be using two distinct variables for result-of-prompt and
> result-of-excision to make it obvious what the flaming dingbats is going
> on).
> 
> Another worry of mine is that I don't understand why fts_skip_tree is
> skipping an entry *other* than ent the second time it's called. Naively
> I'd have assumed fts_skip_tree (fts, ent) would be idempotent: calling
> it repeatedly with the same ent should do the same as calling it only
> once. But clearly this is not the case, so I'm misreading the code in
> gnulib and/or glibc somehow.

There is an fts_read() in fts_skip_tree() that's consuming the entry.

Pushed at:
https://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=6bf108358

cheers,
Pádraig

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From: Nishant Nayan <nishant.nayan <at> oracle.com>
To: bug-coreutils <at> gnu.org
Subject: "rm -rf *" performs an extra skip when it encounters an immutable
 empty directory
Date: Thu, 26 Nov 2020 16:01:15 +0530

Hi,

The 'rm' utility' is skipping a mutable file when it encounters an 
immutable empty
directory (while deleting group of files and directories). 
Version(/8.22-18.0.1)/

Description: The bug is that rm skips an extra file while it encounters
an immutable empty directory. For example, on doing an "rm -rf *" on "a 
b c foo x y z",
where a,b,c,x,y,z are mutable files and foo is an immutable empty 
directory, the output
was "foo x", as soon as rm encounters an immutable directory, it skips 
it's immediate
next file(x in this case) and deletes all other files.

I would like to know if it's a known bug?


Regards
Nishant Nayan

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