open /dev/null O_NOFOLLOW fails with ELOOP

[Corinna Vinschen]

Hi Glenn,

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.


Thanks,
Corinna