log: include hostname in initial log message

On the very first log message we send to any output, we include
the libvirt version number and package string. In some bug reports
we have been given libvirtd.log files that came from a different
host than the corresponding /var/log/libvirt/qemu log files. So
extend the initial log message to include the hostname too.

eg on first log message we would now see:

 $ libvirtd
 2015-12-04 17:35:36.610+0000: 20917: info : libvirt version: 1.3.0
 2015-12-04 17:35:36.610+0000: 20917: info : hostname: dhcp-1-180.lcy.redhat.com
 2015-12-04 17:35:36.610+0000: 20917: error : qemuMonitorIO:687 : internal error: End of file from monitor

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

src/libvirt_private.syms

@@ -2393,6 +2393,7 @@ virGetGroupID;
 virGetGroupList;
 virGetGroupName;
 virGetHostname;
+virGetHostnameQuiet;
 virGetListenFDs;
 virGetSCSIHostNameByParentaddr;
 virGetSCSIHostNumber;

src/util/virlog.c

@@ -94,7 +94,7 @@ static int virLogNbFilters;
  * after filtering, multiple output can be used simultaneously
  */
 struct _virLogOutput {
-    bool logVersion;
+    bool logInitMessage;
     void *data;
     virLogOutputFunc f;
     virLogCloseFunc c;
@@ -402,7 +402,7 @@ virLogDefineOutput(virLogOutputFunc f,
         goto cleanup;
     }
     ret = virLogNbOutputs++;
-    virLogOutputs[ret].logVersion = true;
+    virLogOutputs[ret].logInitMessage = true;
     virLogOutputs[ret].f = f;
     virLogOutputs[ret].c = c;
     virLogOutputs[ret].data = data;
@@ -452,6 +452,32 @@ virLogVersionString(const char **rawmsg,
     return virLogFormatString(msg, 0, NULL, VIR_LOG_INFO, VIR_LOG_VERSION_STRING);
 }
 
+/* Similar to virGetHostname() but avoids use of error
+ * reporting APIs or logging APIs, to prevent recursion
+ */
+static int
+virLogHostnameString(const char **rawmsg,
+                     char **msg)
+{
+    char *hostname = virGetHostnameQuiet();
+    char *hoststr;
+
+    if (!hostname)
+        return -1;
+
+    if (virAsprintfQuiet(&hoststr, "hostname: %s", hostname) < 0) {
+        VIR_FREE(hostname);
+        return -1;
+    }
+
+    if (virLogFormatString(msg, 0, NULL, VIR_LOG_INFO, hoststr) < 0) {
+        VIR_FREE(hoststr);
+        return -1;
+    }
+    *rawmsg = hoststr;
+    return 0;
+}
+
 
 static void
 virLogSourceUpdate(virLogSourcePtr source)
@@ -533,7 +559,7 @@ virLogVMessage(virLogSourcePtr source,
                const char *fmt,
                va_list vargs)
 {
-    static bool logVersionStderr = true;
+    static bool logInitMessageStderr = true;
     char *str = NULL;
     char *msg = NULL;
     char timestamp[VIR_TIME_STRING_BUFLEN];
@@ -583,16 +609,22 @@ virLogVMessage(virLogSourcePtr source,
      */
     for (i = 0; i < virLogNbOutputs; i++) {
         if (priority >= virLogOutputs[i].priority) {
-            if (virLogOutputs[i].logVersion) {
+            if (virLogOutputs[i].logInitMessage) {
-                const char *rawver;
+                const char *rawinitmsg;
-                char *ver = NULL;
+                char *initmsg = NULL;
-                if (virLogVersionString(&rawver, &ver) >= 0)
+                if (virLogVersionString(&rawinitmsg, &initmsg) >= 0)
                     virLogOutputs[i].f(&virLogSelf, VIR_LOG_INFO,
                                        __FILE__, __LINE__, __func__,
-                                       timestamp, NULL, 0, rawver, ver,
+                                       timestamp, NULL, 0, rawinitmsg, initmsg,
                                        virLogOutputs[i].data);
-                VIR_FREE(ver);
+                VIR_FREE(initmsg);
-                virLogOutputs[i].logVersion = false;
+                if (virLogHostnameString(&rawinitmsg, &initmsg) >= 0)
+                    virLogOutputs[i].f(&virLogSelf, VIR_LOG_INFO,
+                                       __FILE__, __LINE__, __func__,
+                                       timestamp, NULL, 0, rawinitmsg, initmsg,
+                                       virLogOutputs[i].data);
+                VIR_FREE(initmsg);
+                virLogOutputs[i].logInitMessage = false;
             }
             virLogOutputs[i].f(source, priority,
                                filename, linenr, funcname,
@@ -601,16 +633,22 @@ virLogVMessage(virLogSourcePtr source,
         }
     }
     if (virLogNbOutputs == 0) {
-        if (logVersionStderr) {
+        if (logInitMessageStderr) {
-            const char *rawver;
+            const char *rawinitmsg;
-            char *ver = NULL;
+            char *initmsg = NULL;
-            if (virLogVersionString(&rawver, &ver) >= 0)
+            if (virLogVersionString(&rawinitmsg, &initmsg) >= 0)
                 virLogOutputToFd(&virLogSelf, VIR_LOG_INFO,
                                  __FILE__, __LINE__, __func__,
-                                 timestamp, NULL, 0, rawver, ver,
+                                 timestamp, NULL, 0, rawinitmsg, initmsg,
                                  (void *) STDERR_FILENO);
-            VIR_FREE(ver);
+            VIR_FREE(initmsg);
-            logVersionStderr = false;
+            if (virLogHostnameString(&rawinitmsg, &initmsg) >= 0)
+                virLogOutputToFd(&virLogSelf, VIR_LOG_INFO,
+                                 __FILE__, __LINE__, __func__,
+                                 timestamp, NULL, 0, rawinitmsg, initmsg,
+                                 (void *) STDERR_FILENO);
+            VIR_FREE(initmsg);
+            logInitMessageStderr = false;
         }
         virLogOutputToFd(source, priority,
                          filename, linenr, funcname,

src/util/virutil.c

@@ -662,16 +662,18 @@ char *virIndexToDiskName(int idx, const char *prefix)
  *         we got from getaddrinfo().  Return the value from gethostname()
  *         and hope for the best.
  */
-char *virGetHostname(void)
+static char *
+virGetHostnameImpl(bool quiet)
 {
     int r;
-    char hostname[HOST_NAME_MAX+1], *result;
+    char hostname[HOST_NAME_MAX+1], *result = NULL;
     struct addrinfo hints, *info;
 
     r = gethostname(hostname, sizeof(hostname));
     if (r == -1) {
-        virReportSystemError(errno,
+        if (!quiet)
-                             "%s", _("failed to determine host name"));
+            virReportSystemError(errno,
+                                 "%s", _("failed to determine host name"));
         return NULL;
     }
     NUL_TERMINATE(hostname);
@@ -683,7 +685,7 @@ char *virGetHostname(void)
          * string as-is; it's up to callers to check whether "localhost"
          * is allowed.
          */
-        ignore_value(VIR_STRDUP(result, hostname));
+        ignore_value(VIR_STRDUP_QUIET(result, hostname));
         goto cleanup;
     }
 
@@ -696,9 +698,10 @@ char *virGetHostname(void)
     hints.ai_family = AF_UNSPEC;
     r = getaddrinfo(hostname, NULL, &hints, &info);
     if (r != 0) {
-        VIR_WARN("getaddrinfo failed for '%s': %s",
+        if (!quiet)
-                 hostname, gai_strerror(r));
+            VIR_WARN("getaddrinfo failed for '%s': %s",
-        ignore_value(VIR_STRDUP(result, hostname));
+                     hostname, gai_strerror(r));
+        ignore_value(VIR_STRDUP_QUIET(result, hostname));
         goto cleanup;
     }
 
@@ -711,18 +714,34 @@ char *virGetHostname(void)
          * localhost.  Ignore the canonicalized name and just return the
          * original hostname
          */
-        ignore_value(VIR_STRDUP(result, hostname));
+        ignore_value(VIR_STRDUP_QUIET(result, hostname));
     else
         /* Caller frees this string. */
-        ignore_value(VIR_STRDUP(result, info->ai_canonname));
+        ignore_value(VIR_STRDUP_QUIET(result, info->ai_canonname));
 
     freeaddrinfo(info);
 
  cleanup:
+    if (!result)
+        virReportOOMError();
     return result;
 }
 
 
+char *
+virGetHostname(void)
+{
+    return virGetHostnameImpl(false);
+}
+
+
+char *
+virGetHostnameQuiet(void)
+{
+    return virGetHostnameImpl(true);
+}
+
+
 char *
 virGetUserDirectory(void)
 {

src/util/virutil.h

@@ -132,6 +132,7 @@ static inline int pthread_sigmask(int how,
 # endif
 
 char *virGetHostname(void);
+char *virGetHostnameQuiet(void);
 
 char *virGetUserDirectory(void);
 char *virGetUserDirectoryByUID(uid_t uid);