From 4afba28d559511a5ee03e005b65be8323bf26ad3 Mon Sep 17 00:00:00 2001
From: Justin Pettit <jpettit@nicira.com>
Date: Wed, 17 Oct 2012 23:11:53 -0700
Subject: [PATCH] dpif: Add new dpif_port_exists() function.

Provide the ability to determine whether a port exists in a datapath
without having to deal with a "dpif_port" structure as with
dpif_port_query_by_name().  A future patch will use this function.

Signed-off-by: Justin Pettit <jpettit@nicira.com>
---
 lib/dpif-linux.c    |  2 +-
 lib/dpif-netdev.c   |  4 ++--
 lib/dpif-provider.h | 10 ++++++----
 lib/dpif.c          | 14 ++++++++++++++
 lib/dpif.h          |  1 +
 5 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/lib/dpif-linux.c b/lib/dpif-linux.c
index 6b36ef60..75bfc458 100644
--- a/lib/dpif-linux.c
+++ b/lib/dpif-linux.c
@@ -492,7 +492,7 @@ dpif_linux_port_query__(const struct dpif *dpif, uint32_t port_no,
             /* A query by name reported that 'port_name' is in some datapath
              * other than 'dpif', but the caller wants to know about 'dpif'. */
             error = ENODEV;
-        } else {
+        } else if (dpif_port) {
             dpif_port->name = xstrdup(reply.name);
             dpif_port->type = xstrdup(netdev_vport_get_netdev_type(&reply));
             dpif_port->port_no = reply.port_no;
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 7f91f48b..a80b1b06 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -522,7 +522,7 @@ dpif_netdev_port_query_by_number(const struct dpif *dpif, uint32_t port_no,
     int error;
 
     error = get_port_by_number(dp, port_no, &port);
-    if (!error) {
+    if (!error && dpif_port) {
         answer_port_query(port, dpif_port);
     }
     return error;
@@ -537,7 +537,7 @@ dpif_netdev_port_query_by_name(const struct dpif *dpif, const char *devname,
     int error;
 
     error = get_port_by_name(dp, devname, &port);
-    if (!error) {
+    if (!error && dpif_port) {
         answer_port_query(port, dpif_port);
     }
     return error;
diff --git a/lib/dpif-provider.h b/lib/dpif-provider.h
index c51b1dfa..bc189429 100644
--- a/lib/dpif-provider.h
+++ b/lib/dpif-provider.h
@@ -122,11 +122,13 @@ struct dpif_class {
     /* Removes port numbered 'port_no' from 'dpif'. */
     int (*port_del)(struct dpif *dpif, uint32_t port_no);
 
-    /* Queries 'dpif' for a port with the given 'port_no' or 'devname'.  Stores
-     * information about the port into '*port' if successful.
+    /* Queries 'dpif' for a port with the given 'port_no' or 'devname'.
+     * If 'port' is not null, stores information about the port into
+     * '*port' if successful.
      *
-     * The caller takes ownership of data in 'port' and must free it with
-     * dpif_port_destroy() when it is no longer needed. */
+     * If 'port' is not null, the caller takes ownership of data in
+     * 'port' and must free it with dpif_port_destroy() when it is no
+     * longer needed. */
     int (*port_query_by_number)(const struct dpif *dpif, uint32_t port_no,
                                 struct dpif_port *port);
     int (*port_query_by_name)(const struct dpif *dpif, const char *devname,
diff --git a/lib/dpif.c b/lib/dpif.c
index d8ca0617..952a502d 100644
--- a/lib/dpif.c
+++ b/lib/dpif.c
@@ -486,6 +486,20 @@ dpif_port_destroy(struct dpif_port *dpif_port)
     free(dpif_port->type);
 }
 
+/* Checks if port named 'devname' exists in 'dpif'.  If so, returns
+ * true; otherwise, returns false. */
+bool
+dpif_port_exists(const struct dpif *dpif, const char *devname)
+{
+    int error = dpif->dpif_class->port_query_by_name(dpif, devname, NULL);
+    if (error != 0 && error != ENODEV) {
+        VLOG_WARN_RL(&error_rl, "%s: failed to query port %s: %s",
+                     dpif_name(dpif), devname, strerror(error));
+    }
+
+    return !error;
+}
+
 /* Looks up port number 'port_no' in 'dpif'.  On success, returns 0 and
  * initializes '*port' appropriately; on failure, returns a positive errno
  * value.
diff --git a/lib/dpif.h b/lib/dpif.h
index db08d785..bd6095ac 100644
--- a/lib/dpif.h
+++ b/lib/dpif.h
@@ -85,6 +85,7 @@ struct dpif_port {
 };
 void dpif_port_clone(struct dpif_port *, const struct dpif_port *);
 void dpif_port_destroy(struct dpif_port *);
+bool dpif_port_exists(const struct dpif *dpif, const char *devname);
 int dpif_port_query_by_number(const struct dpif *, uint32_t port_no,
                               struct dpif_port *);
 int dpif_port_query_by_name(const struct dpif *, const char *devname,
-- 
2.30.2