Send virLogMetadata fields onto the journal

The systemd journal accepts arbitrary user specified log
fields. These can be passed into virLogMessage via the
virLogMetadata structure. Allow up to 5 custom fields to
be reported by libvirt callers.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/util/virlog.c

@@ -1153,7 +1153,7 @@ virLogOutputToJournald(virLogSource source,
                        int linenr,
                        const char *funcname,
                        const char *timestamp ATTRIBUTE_UNUSED,
-                       virLogMetadataPtr metadata ATTRIBUTE_UNUSED,
+                       virLogMetadataPtr metadata,
                        unsigned int flags,
                        const char *rawstr,
                        const char *str ATTRIBUTE_UNUSED,
@@ -1172,8 +1172,11 @@ virLogOutputToJournald(virLogSource source,
      * be a tmpfs, and one that is available from early boot on
      * and where unprivileged users can create files. */
     char path[] = "/dev/shm/journal.XXXXXX";
+    size_t nmetadata = 0;
 
-#  define NUM_FIELDS 6
+#  define NUM_FIELDS_CORE 6
+#  define NUM_FIELDS_META 5
+#  define NUM_FIELDS (NUM_FIELDS_CORE + NUM_FIELDS_META)
     struct iovec iov[NUM_FIELDS * 5];
     char iov_bufs[NUM_FIELDS][JOURNAL_BUF_SIZE];
     struct journalState state;
@@ -1192,6 +1195,17 @@ virLogOutputToJournald(virLogSource source,
     journalAddInt(&state, "CODE_LINE", linenr);
     if (funcname)
         journalAddString(&state, "CODE_FUNC", funcname);
+    if (metadata != NULL) {
+        while (metadata->key != NULL &&
+               nmetadata < NUM_FIELDS_META) {
+            if (metadata->s != NULL)
+                journalAddString(&state, metadata->key, metadata->s);
+            else
+                journalAddInt(&state, metadata->key, metadata->iv);
+            metadata++;
+            nmetadata++;
+        }
+    }
 
     memset(&sa, 0, sizeof(sa));
     sa.sun_family = AF_UNIX;