Clean up error handling in libstand filesystem code to be more consistent:

- bzipfs and gzipfs now properly return errno values directly from their
  read routines rather than returning -1.
- missing errno values on error returns for the seek routines on almost
  all filesystems were added.
- fstat() now returns -1 if an error occurs rather than ignoring it.
- nfs's readdir() routine now reports valid errno values if an error or
  EOF occurs rather than EPERM  (It was just returning 0 for success and
  1 for failure).
- nullfs used the wrong semantics for every function besides close() and
  seek().  Getting it right for close() appears to be an accident at that.
- read() for buffered files no longer returns 0 (EOF) if an error occurs,
  but returns -1 instead.

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/libstand/fstat.c b/lib/libstand/fstat.c
index 3a5f39f..7d95360 100644
--- a/lib/libstand/fstat.c
+++ b/lib/libstand/fstat.c
@@ -59,5 +59,7 @@ fstat(fd, sb)
 	}
 
 	errno = (f->f_ops->fo_stat)(f, sb);
+	if (errno)
+		return (-1);
 	return (0);
 }