- Fix error reporting when checking order number via NIS: we return zero

  on a failure, but if we're checking a corrupt map we could also get back
  a zero from ypserv without really encountering any actual error. Flag this
  condition and generate an meaningful error message.

- Fix transmission of ypxfr_clear to ypserv: error checking was wrong
  and we sending YPXFR_YPERR as an error status instead of YPXFR_CLEAR.

- To help avoid a race condition (or at least reduce the likelyhood of
  it occuring), use rename() to move a newly transfered map into place
  instead of unlink()ing the old one first and then renaming. Da man page
  sez that rename should do the unlink() for us. This prevents ypserv
  from returning 'no such map in domain' when asked to query a map which
  ypxfr has just unlink()ed but not yet replaced.

1 files changed, 22 insertions, 14 deletions

diff --git a/libexec/ypxfr/ypxfr_main.c b/libexec/ypxfr/ypxfr_main.c
index e603409..cc4e1b4 100644
--- a/libexec/ypxfr/ypxfr_main.c
+++ b/libexec/ypxfr/ypxfr_main.c
@@ -29,7 +29,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: ypxfr_main.c,v 1.13 1996/01/06 19:59:41 wpaul Exp $
+ *	$Id: ypxfr_main.c,v 1.15 1996/01/10 17:41:55 wpaul Exp $
  */
 #include <stdio.h>
 #include <stdlib.h>
@@ -43,13 +43,14 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <rpc/rpc.h>
+#include <rpc/clnt.h>
 #include <rpcsvc/yp.h>
 struct dom_binding {};
 #include <rpcsvc/ypclnt.h>
 #include "ypxfr_extern.h"
 
 #ifndef lint
-static const char rcsid[] = "$Id: ypxfr_main.c,v 1.13 1996/01/06 19:59:41 wpaul Exp $";
+static const char rcsid[] = "$Id: ypxfr_main.c,v 1.15 1996/01/10 17:41:55 wpaul Exp $";
 #endif
 
 char *progname = "ypxfr";
@@ -333,7 +334,8 @@ the local domain name isn't set");
 					     ypxfr_mapname,
 					     ypxfr_master, 0)) == 0) {
 		yp_error("failed to get order number of %s: %s",
-				ypxfr_mapname, ypxfrerr_string(yp_errno));
+				ypxfr_mapname, yp_errno == YPXFR_SUCC ?
+				"map has order 0" : ypxfrerr_string(yp_errno));
 		ypxfr_exit(YPXFR_YPERR,NULL);
 	}
 
@@ -454,7 +456,8 @@ the local domain name isn't set");
 					     ypxfr_mapname,
 					     ypxfr_master, 0)) == 0) {
 		yp_error("failed to get order number of %s: %s",
-				ypxfr_mapname, ypxfrerr_string(yp_errno));
+				ypxfr_mapname, yp_errno == YPXFR_SUCC ?
+				"map has order 0" : ypxfrerr_string(yp_errno));
 		ypxfr_exit(YPXFR_YPERR,&ypxfr_temp_map);
 	}
 
@@ -466,21 +469,26 @@ the local domain name isn't set");
 	 * The FreeBSD ypserv doesn't really need this, but we send it
 	 * here anyway for the sake of consistency.
 	 */
-	if (!ypxfr_clear) {
+	if (ypxfr_clear) {
 		char in = 0;
 		char *out = NULL;
-		if (callrpc("localhost",YPPROG,YPVERS,YPPROC_CLEAR, xdr_void,
-			(void *)&in, xdr_void, (void *)out) == NULL) {
-			yp_error("failed to send 'clear' to local ypserv");
-			ypxfr_exit(YPXFR_YPERR, &ypxfr_temp_map);
+		int stat;
+		if ((stat = callrpc("localhost",YPPROG,YPVERS,YPPROC_CLEAR,
+			xdr_void, (void *)&in,
+			xdr_void, (void *)out)) != RPC_SUCCESS) {
+			yp_error("failed to send 'clear' to local ypserv: %s",
+				 clnt_sperrno((enum clnt_stat) stat));
+			ypxfr_exit(YPXFR_CLEAR, &ypxfr_temp_map);
 		}
 	}
 
-	if (unlink(buf) == -1 && errno != ENOENT) {
-		yp_error("unlink(%s) failed: %s", buf, strerror(errno));
-		ypxfr_exit(YPXFR_FILE,NULL);
-	}
-
+	/*
+	 * Put the new map in place immediately. I'm not sure if the
+	 * kernel does an unlink() and rename() atomically in the event
+	 * that we move a new copy of a map over the top of an existing
+	 * one, but there's less chance of a race condition happening
+	 * than if we were to do the unlink() ourselves.
+	 */
 	if (rename(ypxfr_temp_map, buf) == -1) {
 		yp_error("rename(%s,%s) failed: %s", ypxfr_temp_map, buf,
 							strerror(errno));