Force all logs to go to the round robbin memory buffer

Initially only the log actually written out by libvirt were
saved on the memory buffer, this patch forces all informations
including info and debug to be saved in memory too. This is
useful to get full data in case of crash.

src/util/logging.c

@@ -569,11 +569,12 @@ void virLogMessage(const char *category, int priority, const char *funcname,
                    long long linenr, int flags, const char *fmt, ...) {
     static bool logVersionStderr = true;
     char *str = NULL;
-    char *msg;
+    char *msg = NULL;
     struct timeval cur_time;
     struct tm time_info;
     int len, fprio, i, ret;
     int saved_errno = errno;
+    int emit = 1;
 
     if (!virLogInitialized)
         virLogStartup();
@@ -587,9 +588,9 @@ void virLogMessage(const char *category, int priority, const char *funcname,
     fprio = virLogFiltersCheck(category);
     if (fprio == 0) {
         if (priority < virLogDefaultPriority)
-            goto cleanup;
+            emit = 0;
     } else if (priority < fprio) {
-        goto cleanup;
+        emit = 0;
     }
 
     /*
@@ -609,8 +610,8 @@ void virLogMessage(const char *category, int priority, const char *funcname,
         goto cleanup;
 
     /*
-     * Log based on defaults, first store in the history buffer
-     * then push the message on the outputs defined, if none
+     * Log based on defaults, first store in the history buffer,
+     * then if emit push the message on the outputs defined, if none
      * use stderr.
      * NOTE: the locking is a single point of contention for multiple
      *       threads, but avoid intermixing. Maybe set up locks per output
@@ -618,6 +619,9 @@ void virLogMessage(const char *category, int priority, const char *funcname,
      */
     len = strlen(msg);
     virLogStr(msg, len);
+    if (emit == 0)
+        goto cleanup;
+
     virLogLock();
     for (i = 0; i < virLogNbOutputs;i++) {
         if (priority >= virLogOutputs[i].priority) {
@@ -647,8 +651,8 @@ void virLogMessage(const char *category, int priority, const char *funcname,
     }
     virLogUnlock();
 
-    VIR_FREE(msg);
 cleanup:
+    VIR_FREE(msg);
     errno = saved_errno;
 }