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, 3 insertions, 2 deletions

diff --git a/lib/libstand/nfs.c b/lib/libstand/nfs.c
index 82fa08b..1c439a8 100644
--- a/lib/libstand/nfs.c
+++ b/lib/libstand/nfs.c
@@ -674,6 +674,7 @@ nfs_seek(f, offset, where)
 		d->off = size - offset;
 		break;
 	default:
+		errno = EINVAL;
 		return (-1);
 	}
 
@@ -741,7 +742,7 @@ nfs_readdir(struct open_file *f, struct dirent *d)
 		buf  = rdata.d;
 		roff = (struct nfs_readdir_off *)buf;
 		if (ntohl(roff->cookie) != 0)
-			return 1;
+			return EIO;
 	}
 	roff = (struct nfs_readdir_off *)buf;
 
@@ -749,7 +750,7 @@ nfs_readdir(struct open_file *f, struct dirent *d)
 		eof = ntohl((roff+1)->cookie);
 		if (eof) {
 			cookie = 0;
-			return 1;
+			return ENOENT;
 		}
 		goto refill;
 	}