Revert "utils: Remove the logging of errors from virNetDevSendEthtoolIoctl"

This reverts commit 6f2a0198.

This commit removed error reporting from virNetDevSendEthtoolIoctl
pushing responsibility onto the callers. This is wrong, however,
since virNetDevSendEthtoolIoctl calls virNetDevSetupControl
which can still report errors. So as a result virNetDevSendEthtoolIoctl
may or may not report errors depending on which bit of it fails, and as
a result callers now overwrite some errors.

It also introduced a regression causing unprivileged libvirtd to
spew error messages to the console due to inability to query the
NIC features, an error which was previously ignored.

virNetDevSetupControlFull:148 : Cannot open network interface control socket: Operation not permitted
virNetDevFeatureAvailable:3062 : Cannot get device wlp3s0 flags: Operation not permitted
virNetDevSetupControlFull:148 : Cannot open network interface control socket: Operation not permitted
virNetDevFeatureAvailable:3062 : Cannot get device wlp3s0 flags: Operation not permitted
virNetDevSetupControlFull:148 : Cannot open network interface control socket: Operation not permitted
virNetDevFeatureAvailable:3062 : Cannot get device wlp3s0 flags: Operation not permitted
virNetDevSetupControlFull:148 : Cannot open network interface control socket: Operation not permitted
virNetDevFeatureAvailable:3062 : Cannot get device wlp3s0 flags: Operation not permitted

Looking back at the original posting I see no explanation of why
thsi refactoring was needed, so reverting the clearly broken
error reporting logic looks like the best option.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/util/virnetdev.c

@@ -3151,15 +3151,39 @@ static int
 virNetDevSendEthtoolIoctl(const char *ifname, void *cmd)
 {
     int ret = -1;
-    int fd;
-    struct ifreq ifr;
+    int sock = -1;
+    virIfreq ifr;
 
-    if ((fd = virNetDevSetupControl(ifname, &ifr)) < 0)
-        return ret;
+    sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
+    if (sock < 0) {
+        virReportSystemError(errno, "%s", _("Cannot open control socket"));
+        goto cleanup;
+    }
+
+    memset(&ifr, 0, sizeof(ifr));
+    strcpy(ifr.ifr_name, ifname);
     ifr.ifr_data = cmd;
-    ret = ioctl(fd, SIOCETHTOOL, &ifr);
+    ret = ioctl(sock, SIOCETHTOOL, &ifr);
+    if (ret != 0) {
+        switch (errno) {
+            case EPERM:
+                VIR_DEBUG("ethtool ioctl: permission denied");
+                break;
+            case EINVAL:
+                VIR_DEBUG("ethtool ioctl: invalid request");
+                break;
+            case EOPNOTSUPP:
+                VIR_DEBUG("ethtool ioctl: request not supported");
+                break;
+            default:
+                virReportSystemError(errno, "%s", _("ethtool ioctl error"));
+                goto cleanup;
+        }
+    }
 
-    VIR_FORCE_CLOSE(fd);
+ cleanup:
+    if (sock)
+        VIR_FORCE_CLOSE(sock);
     return ret;
 }
 
@@ -3176,12 +3200,12 @@ virNetDevSendEthtoolIoctl(const char *ifname, void *cmd)
 static int
 virNetDevFeatureAvailable(const char *ifname, struct ethtool_value *cmd)
 {
+    int ret = -1;
+
     cmd = (void*)cmd;
-    if (virNetDevSendEthtoolIoctl(ifname, cmd) < 0) {
-        virReportSystemError(errno, _("Cannot get device %s flags"), ifname);
-        return -1;
-    }
-    return cmd->data > 0 ? 1 : 0;
+    if (!virNetDevSendEthtoolIoctl(ifname, cmd))
+        ret = cmd->data > 0 ? 1 : 0;
+    return ret;
 }
 
 
@@ -3198,12 +3222,12 @@ virNetDevFeatureAvailable(const char *ifname, struct ethtool_value *cmd)
 static int
 virNetDevGFeatureAvailable(const char *ifname, struct ethtool_gfeatures *cmd)
 {
+    int ret = -1;
+
     cmd = (void*)cmd;
-    if (virNetDevSendEthtoolIoctl(ifname, cmd) < 0) {
-        virReportSystemError(errno, _("Cannot get device %s generic features"), ifname);
-        return -1;
-    }
-    return FEATURE_BIT_IS_SET(cmd->features, TX_UDP_TNL, active);
+    if (!virNetDevSendEthtoolIoctl(ifname, cmd))
+        ret = FEATURE_BIT_IS_SET(cmd->features, TX_UDP_TNL, active);
+    return ret;
 }
 # endif