virNetDevBridgeGet: Don't require users to virNetDevSetupControl

So far, this function has just three callers. Two of them call
virNetDevSetupControl to create a socket that we can then
optionally use for ioctl() to fetch data. However, querying sysfs
is preferred. Therefore it doesn't make much sense to require
users to set up the socket if they don't even know it will be
used in favour of sysfs. We can set up the socket iff we need to.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

src/util/virnetdevbridge.c

@@ -169,12 +169,12 @@ static int virNetDevBridgeSet(const char *brname,
 
 static int virNetDevBridgeGet(const char *brname,
                               const char *paramname,  /* sysfs param name */
-                              unsigned long *value,   /* current value */
-                              int fd,                 /* control socket */
-                              struct ifreq *ifr)      /* pre-filled bridge name */
+                              unsigned long *value)   /* current value */
 {
     char *path = NULL;
     int ret = -1;
+    int fd = -1;
+    struct ifreq ifr;
 
     if (virAsprintf(&path, SYSFS_NET_DIR "%s/bridge/%s", brname, paramname) < 0)
         return -1;
@@ -196,7 +196,11 @@ static int virNetDevBridgeGet(const char *brname,
     } else {
         struct __bridge_info info;
         unsigned long args[] = { BRCTL_GET_BRIDGE_INFO, (unsigned long)&info, 0, 0 };
-        ifr->ifr_data = (char*)&args;
+
+        if ((fd = virNetDevSetupControl(brname, &ifr)) < 0)
+            goto cleanup;
+
+        ifr.ifr_data = (char*)&args;
         if (ioctl(fd, SIOCDEVPRIVATE, ifr) < 0) {
             virReportSystemError(errno,
                                  _("Unable to get bridge %s %s"), brname, paramname);
@@ -216,6 +220,7 @@ static int virNetDevBridgeGet(const char *brname,
 
     ret = 0;
  cleanup:
+    VIR_FORCE_CLOSE(fd);
     VIR_FREE(path);
     return ret;
 }
@@ -825,20 +830,12 @@ int virNetDevBridgeSetSTPDelay(const char *brname,
 int virNetDevBridgeGetSTPDelay(const char *brname,
                                int *delayms)
 {
-    int fd = -1;
     int ret = -1;
-    struct ifreq ifr;
     unsigned long val;
 
-    if ((fd = virNetDevSetupControl(brname, &ifr)) < 0)
-        goto cleanup;
-
-    ret = virNetDevBridgeGet(brname, "forward_delay", &val,
-                             fd, &ifr);
+    ret = virNetDevBridgeGet(brname, "forward_delay", &val);
     *delayms = JIFFIES_TO_MS(val);
 
- cleanup:
-    VIR_FORCE_CLOSE(fd);
     return ret;
 }
 
@@ -885,20 +882,12 @@ int virNetDevBridgeSetSTP(const char *brname,
 int virNetDevBridgeGetSTP(const char *brname,
                           bool *enabled)
 {
-    int fd = -1;
     int ret = -1;
-    struct ifreq ifr;
     unsigned long val;
 
-    if ((fd = virNetDevSetupControl(brname, &ifr)) < 0)
-        goto cleanup;
-
-    ret = virNetDevBridgeGet(brname, "stp_state", &val,
-                             fd, &ifr);
+    ret = virNetDevBridgeGet(brname, "stp_state", &val);
     *enabled = val ? true : false;
 
- cleanup:
-    VIR_FORCE_CLOSE(fd);
     return ret;
 }
 #elif defined(HAVE_BSD_BRIDGE_MGMT)
@@ -1000,7 +989,7 @@ virNetDevBridgeGetVlanFiltering(const char *brname,
     int ret = -1;
     unsigned long value;
 
-    if (virNetDevBridgeGet(brname, "vlan_filtering", &value, -1, NULL) < 0)
+    if (virNetDevBridgeGet(brname, "vlan_filtering", &value) < 0)
         goto cleanup;
 
     *enable = !!value;