[exim] Re: Bad file descriptor on logs?

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Author: Evgeniy Berdnikov
Date:  
To: exim-users
Subject: [exim] Re: Bad file descriptor on logs?
On Thu, Sep 26, 2024 at 09:50:39AM -0700, Ian Z via Exim-users wrote:
> On Thu, Sep 26, 2024 at 09:15:07AM GMT, Cam Ellison via Exim-users wrote:
>
> > > Sep 23 00:00:08 mail exim[1468704]: 2024-09-23 00:00:08 1ssUci-006A4f-Ph failed to write to main log: length=91 result=-1 errno=9 (Bad file descriptor)
> > > Sep 23 00:00:08 mail exim[1468704]: write failed on panic log: length=116 result=-1 errno=9 (Bad file descriptor)

[...]
> Does exim under any circumstances close() the file descriptors
> for the logs?


Exim open()s mainlog/rejectlog/paniclog for writing and close() it on
completion of write. Exim listener does not keep them open, it can be
checked via /proc/<pid>/fd on Linux and similar kernel interfaces
on other OSes.

> I feel it shouldn't ever do that, but I have no other explanation for
> these errors.


Probably memory in running Exim instance is corrupted, leading to wrong
contents of memory cells where file descriptors are stored. But such
corruption should occur in a small piece of code between open() and close().
Of course, it may be a bug, triggered by some exotic condition.

> And how did _these_ errors get logged anyway? Is it
> because exim runs under systemd and systemd captures its stdout and
> stderr?


Yes, cited lines looks like syslog records, it may be also a result
of stderr capture by systemd.
--
Eugene Berdnikov

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