Re: [patch] link.2: ERRORS: add ENOENT when target is deleted

["Alejandro Colomar (man-pages)" <alx.manpages@gmail.com>]

Hi Mathias & Michael,

Please, see a fix below.

Cheers,

Alex

On 11/26/20 11:00 AM, Michael Kerrisk (man-pages) wrote:
> On 11/25/20 2:27 PM, Mathias Rav wrote:
>> Linux kernel commit aae8a97d3ec30788790d1720b71d76fd8eb44b73
>> (part of kernel release v2.6.39) added a check to disallow creating a
>> hardlink to an unlinked file.
>>
>> Signed-off-by: Mathias Rav <m@git.strova.dk>
> 
> Thanks, Matthias. Patch applied.
> 
>> ---
>> The manual page already describes the trick of using AT_SYMLINK_FOLLOW
>> as an alternative to AT_EMPTY_PATH, and for AT_EMPTY_PATH the manual
>> page already notes that it "will generally not work if the file has a
>> link count of zero". However, the precise error (ENOENT) is not mentioned,
>> and the error case isn't mentioned in the ERRORS section at all.
>>
>> This makes it easy to overlook the fact that the AT_SYMLINK_FOLLOW
>> trick on /proc/self/fd/NN won't work on deleted files, as evidenced by
>> the follow message (which turns up when googling "linkat deleted ENOENT"):
>> https://groups.google.com/g/linux.kernel/c/zZO4lqqwp64
> 
> I think the above piece is actually worth including in the
> commit message, so I added it.
> 
> Thanks,
> 
> Michael
> 
>>  man2/link.2 | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/man2/link.2 b/man2/link.2
>> index 1e7b2efd8..202119c6e 100644
>> --- a/man2/link.2
>> +++ b/man2/link.2
>> @@ -318,6 +318,10 @@ open(path, O_TMPFILE | O_EXCL, mode);
>>  .IP
>>  See
>>  .BR open (2).

+.TP

>> +.B ENOENT
>> +An attempt was made to link to a
>> +.I /proc/self/fd/NN
>> +file corresponding to a file that has been deleted.
>>  .TP
>>  .B ENOENT
>>  .I oldpath
>>
> 
>