[tor-dev] Named pipes with tor

[Nick Mathewson]

On Tue, Apr 15, 2014 at 2:27 PM, Nick Mathewson <nickm at alum.mit.edu> wrote:
> On Mon, Apr 14, 2014 at 5:32 AM, carlo von lynX
> <lynX at time.to.get.psyced.org> wrote:
>  [...]
>> So the question is, would it be okay to catch ESPIPE in
>> all cases, thus having it ignored in tor_fd_seekend,
>> or just catch it in add_file_log? Or is there a reason to
>> impede the use of unix named pipes under all circumstances?
>
> I think it's fine to ignore that failure from tor_fd_seekend in this
> case.  Actually, I'm not clear, looking at the code, why it's there at
> all: it seems to me that O_APPEND should already put us at the end of
> the file, right?  It's not clear to me why we mask out O_APPEND in
> start_writing_to_file().  Maybe looking at the git logs will shine
> some light on it...

Ah.  Apparently, O_APPEND has additional semantics beyond when we're
opening the file.   See commit
37bd9181f07b198ce43489adb5fdb457eef8cfff