open /dev/null O_NOFOLLOW fails with ELOOP

[Corinna Vinschen]

Hi Glenn,

On Dec 21 12:31, Corinna Vinschen via Cygwin wrote:
> On Dec 21 06:15, gs-cygwin.com--- via Cygwin wrote:
> > open /dev/null O_NOFOLLOW fails with ELOOP
> > 
> > Windows 10, 64-bit cygwin
> > 
> > Failed with my existing install, then I ran setup.exe, updated to
> > latest, and my tests still failed.
> > 
> > a.c
> > ---
> > 
> > #include <sys/types.h>
> > #include <fcntl.h>
> > #include <stdio.h>
> > 
> > int main (void)
> > {
> >     int fd = open("/dev/null", O_RDWR | O_NOFOLLOW, 0);
> >     if (fd < 0)
> >         perror("open(/dev/null)");
> >     return fd;
> > }
> > 
> > 
> > $ gcc a.c ; ./a.exe
> > open(/dev/null): Too many levels of symbolic links
> > 
> > While troubleshooting this, there were times where it succeeded and then
> > times where it failed, though it failed most of the time.  It did not
> > fail (or succeed) randomly, but seemingly in streaks.
> > 
> > Trying to start lighttpd seems to run into this bug reliably,
> >   $ /usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf
> > In the next release of lighttpd, I may end up omitting O_NOFOLLOW
> > if __CYGWIN__ is defined.
> 
> Thanks for the report.  I think I see what's going on, stay tuned.

I pushed a patch:
https://cygwin.com/git/?p=newlib-cygwin.git;a=commitdiff;h=09cb4cd2940f

Please try the latest test release cygwin-3.5.0-0.60.g09cb4cd2940f.
For installation, see https://cygwin.com/faq.html#faq.setup.testrels


Thanks,
Corinna