[Bug libfortran/21593] FAIL: gfortran.dg/dev_null.f90

["sgk at troutmask dot apl dot washington dot edu" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From sgk at troutmask dot apl dot washington dot edu  2005-06-18 16:19 -------
Subject: Re:  FAIL: gfortran.dg/dev_null.f90

> int main (void)
> {
>   int fd = open ("/dev/null", O_RDWR);
>   ftruncate (fd, 0);
>   printf ("%d\n", errno);
>   close (fd);
>   return 0;
> }
> 
> On linux, this code outputs 22 (EINVAL), while on freebsd it outputs 0. I
> suppose the reason of the failure is similar for other platforms.
> 
> I'm sure what to do, but I don't think I'll take too much time thinking about
> it, since this a low-priority bug really.

According to null(4) man page,  reading or writing to /dev/null
on FreeBSD always succeeds.  According to the ftruncate man page,
upon successful completion, the value 0 is returned.

The redhat system that I checked, identifies /dev/null as "a 
special file" in null(4).  The ftruncate man page specifically
states the behavior for "regular files".  So redhat has wiggle
room with its use of errno.

POSIX
http://www.opengroup.org/onlinepubs/009695399/toc.htm
If fildes refers to any other file type, except a shared memory
object, the result is unspecified.

So, we need to check both the return value of ftruncate and
the value of errno.



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21593