bug#10489: 24.0.92; dired-do-copy may create infinite directory hierarchy

[Thierry Volpiatto]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Thierry Volpiatto <thierry.volpiatto@gmail.com>
>> Cc: 10489@debbugs.gnu.org
>> Date: Fri, 13 Jan 2012 09:38:30 +0100
>> 
>> > I don't think this will solves all the use cases.  File names are not
>> > strings, you cannot compare them as literal strings and hope to plumb
>> > all the leaks.
>> A test with `equal' is already used in `dired-create-files',
>> (equal from to) 
>> Is it the correct way to compare two filenames?
>
> I don't see how `equal' could help, unless someone teaches it to treat
> strings that are file names specially.  I don't see such treatment in
> the current sources.
>
>> > Some situations which I think this patch will not handle correctly:
>> >
>> >  . file names with different letter-case on a case-insensitive file
>> >    system
>> Can you provide example or better a recipe.
>
>   emacs -Q
>   C-x d ~ RET
>   <go to the line showing "Test">
>   C ~/test RET
>   yes RET
>
>> >  . relative vs absolute file names
>> Same.
>
> M-: (dired-copy-file-recursive "foo/../Test" "./Test" t) RET
>
>> >  . file names that are hard links to the same directory (this includes
>> >    the infamous 8+3 short aliases on Windows)
>> Don't know on Windows, (My knowledge of links in windows is very
>> limited) 
>> here it is difficult (impossible as User) to Hardlink a directory:
>> 
>> --8<---------------cut here---------------start------------->8---
>> man ln:
>>      -d, -F, --directory
>>           allow the superuser to attempt to hard link directories
>>           (note: will  probably fail due to  system restrictions,
>>           even for the superuser)
>> --8<---------------cut here---------------end--------------->8---
>
> We don't disallow superusers from using Emacs, nor restrict Emacs
> usage only to filesystems where links to directories are impossible,
> do we? ;-)
I just want to be able to test:

cp "a_hardlink_of_/foo" "/foo"

> And what about symlinks?
>
> On Windows, you can have "C:/PROGRA~1" be the alias of
> "C:/Program Files", for example.
>
> Bottom line, I think you need:
>
>   . make both file names absolute by calling expand-file-name on each
Ok

>   . resolve links by calling file-truename on each (this will handle
>     the 8+3 alias issue, as well as, AFAIK, the issue with links)
Ok

>   . compare case-insensitively on MS-Windows and MS-DOS
let binding case-fold-search should be ok.

Thanks, I will add these modifications to the patch handling remote files.

-- 
  Thierry
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