lkml.org 
[lkml]   [2007]   [Jan]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Finding hardlinks
Hi!

>>>> If user (or script) doesn't specify that flag, it
>>>> doesn't help. I think
>>>> the best solution for these filesystems would be
>>>> either to add new syscall
>>>> int is_hardlink(char *filename1, char *filename2)
>>>> (but I know adding syscall bloat may be objectionable)
>>>
>>> it's also the wrong api; the filenames may have been
>>> changed under you
>>> just as you return from this call, so it really is a
>>> "was_hardlink_at_some_point()" as you specify it.
>>> If you make it work on fd's.. it has a chance at least.
>>
>> Yes, but it doesn't matter --- if the tree changes under
>> "cp -a" command, no one guarantees you what you get.
>> int fis_hardlink(int handle1, int handle 2);
>> Is another possibility but it can't detect hardlinked
>> symlinks.
>
> Ugh. Is it even legal to hardlink symlinks?

Why it shoudln't be? It seems to work quite fine in Linux.

> Anyway, cp -a is not the only application that wants to do hardlink
> detection.

I tested programs for ino_t collision (I intentionally injected it) and
found that CP from coreutils 6.7 fails to copy directories but displays
error messages (coreutils 5 work fine). MC and ARJ skip directories with
colliding ino_t and pretend that operation completed successfuly. FTS
library fails to walk directories returning FTS_DC error. Diffutils, find,
grep fail to search directories with coliding inode numbers. Tar seems
tolerant except incremental backup (which I didn't try). All programs
except diff were tolerant to coliding ino_t on files.

ino_t is no longer unique in many filesystems, it seems like quite serious
data corruption possibility.

Mikulas

> Pavel
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-01-01 23:49    [W:1.730 / U:0.004 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site