virLogVMessage: Don't leak rawinitmsg

Instead of misusing a const string to hold up runtime allocated
data, introduce new variable @hoststr and obey const correctness.

==6879== 15 bytes in 1 blocks are definitely lost in loss record 68 of 1,064
==6879==    at 0x4C29F80: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==6879==    by 0xA7DDF97: vasprintf (in /lib64/libc-2.21.so)
==6879==    by 0x552BBC6: virVasprintfInternal (virstring.c:493)
==6879==    by 0x552BCDB: virAsprintfInternal (virstring.c:514)
==6879==    by 0x54FA44C: virLogHostnameString (virlog.c:468)
==6879==    by 0x54FAB0F: virLogVMessage (virlog.c:645)
==6879==    by 0x54FA680: virLogMessage (virlog.c:531)
==6879==    by 0x54FBBF4: virLogParseOutputs (virlog.c:1130)
==6879==    by 0x11CB4F: daemonSetupLogging (libvirtd.c:685)
==6879==    by 0x11E137: main (libvirtd.c:1297)
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

src/util/virlog.c

@@ -456,7 +456,7 @@ virLogVersionString(const char **rawmsg,
  * reporting APIs or logging APIs, to prevent recursion
  */
 static int
-virLogHostnameString(const char **rawmsg,
+virLogHostnameString(char **rawmsg,
                      char **msg)
 {
     char *hostname = virGetHostnameQuiet();
@@ -612,6 +612,7 @@ virLogVMessage(virLogSourcePtr source,
         if (priority >= virLogOutputs[i].priority) {
             if (virLogOutputs[i].logInitMessage) {
                 const char *rawinitmsg;
+                char *hoststr = NULL;
                 char *initmsg = NULL;
                 if (virLogVersionString(&rawinitmsg, &initmsg) >= 0)
                     virLogOutputs[i].f(&virLogSelf, VIR_LOG_INFO,
@@ -619,11 +620,12 @@ virLogVMessage(virLogSourcePtr source,
                                        timestamp, NULL, 0, rawinitmsg, initmsg,
                                        virLogOutputs[i].data);
                 VIR_FREE(initmsg);
-                if (virLogHostnameString(&rawinitmsg, &initmsg) >= 0)
+                if (virLogHostnameString(&hoststr, &initmsg) >= 0)
                     virLogOutputs[i].f(&virLogSelf, VIR_LOG_INFO,
                                        __FILE__, __LINE__, __func__,
-                                       timestamp, NULL, 0, rawinitmsg, initmsg,
+                                       timestamp, NULL, 0, hoststr, initmsg,
                                        virLogOutputs[i].data);
+                VIR_FREE(hoststr);
                 VIR_FREE(initmsg);
                 virLogOutputs[i].logInitMessage = false;
             }
@@ -636,6 +638,7 @@ virLogVMessage(virLogSourcePtr source,
     if (virLogNbOutputs == 0) {
         if (logInitMessageStderr) {
             const char *rawinitmsg;
+            char *hoststr = NULL;
             char *initmsg = NULL;
             if (virLogVersionString(&rawinitmsg, &initmsg) >= 0)
                 virLogOutputToFd(&virLogSelf, VIR_LOG_INFO,
@@ -643,11 +646,12 @@ virLogVMessage(virLogSourcePtr source,
                                  timestamp, NULL, 0, rawinitmsg, initmsg,
                                  (void *) STDERR_FILENO);
             VIR_FREE(initmsg);
-            if (virLogHostnameString(&rawinitmsg, &initmsg) >= 0)
+            if (virLogHostnameString(&hoststr, &initmsg) >= 0)
                 virLogOutputToFd(&virLogSelf, VIR_LOG_INFO,
                                  __FILE__, __LINE__, __func__,
-                                 timestamp, NULL, 0, rawinitmsg, initmsg,
+                                 timestamp, NULL, 0, hoststr, initmsg,
                                  (void *) STDERR_FILENO);
+            VIR_FREE(hoststr);
             VIR_FREE(initmsg);
             logInitMessageStderr = false;
         }