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Re: syslog function: Bad file descriptor


On Aug  5 19:43, D. Boland wrote:
> Corinna Vinschen wrote:
> > > Somehow the two are connected. The alias database (aliases.db) is built from a plain
> > > text file (aliases). If I leave the aliases file writable to the sendmail user, I
> > > find that the error message strings have been put right into the alias text-file:
> > >
> > > $ cat /etc/mail/aliases
> > > <21>sendmail: PID 1848: alias database /etc/mail/aliases rebuilt by smmspsenet: root
> > > news: root
> > > webmaster: root
> > > www: root
> > > ftp: root
> > > abuse: root
> > > noc: root
> > > security: root
> > > root: SYSTEM
> > > <22>sendmail: PID 1848: /etc/mail/aliases: 9 aliases, longest 6 bytes, 82 bytes
> > > total
> > >
> > > If I make the 'aliases' file read-only, then the file is not corrupted, but the
> > > error occurs.
> > 
> > I don't see that this has to do with syslog.  There's a writev to fd 3,
> > but you stripped the strace so we don't know what fd 3 is connected to.
> > Also, syslog writes the output to the Windows event log by default,
> > unless you have a syslog daemon running, connected to /dev/log.
> > 
> > So I guess we first have to know what fd 3 is connected to, and then
> > how to reproduce the issue.
> > 
> 
> I have the syslogd (inetutils-server package) running as a Windows Service, using
> cygrunsrv.
> 
> I attached the complete strace output. The 'syslog' function works fine while
> running as the cyg_server user, but after a setuid/setgid to the Sendmail 'smmsp'
> user, it fails.
> 
> The output is quite large. I put in printf("syslog: %s\n") calls to mark the spots
> where it happens.

Can you produce another strace for the overwriting case (non-R/O aliases)
for comparison?  Also, can you do the same strace with no syslogd running?

It might be necessary to create a few test versions of Cygwin with more
debug output, but let's please see these straces first.


Thanks,
Corinna

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