From 985a321ac0cba18f7f6721efd89e7f0e3e7fb2bf Mon Sep 17 00:00:00 2001
From: "Daniel P. Berrange" <berrange@redhat.com>
Date: Thu, 6 Sep 2012 16:14:25 +0100
Subject: [PATCH] Wait to receive QMP greeting before sending any monitor
 commands

Technically speaking we should wait until we receive the QMP
greeting message before attempting to send any QMP monitor
commands. Mostly we've got away with this, but there is a race
in some QEMU which cause it to SEGV if you sent it data too
soon after startup. Waiting for the QMP greeting avoids the
race

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 src/qemu/qemu_monitor.c      |  9 ++++++++-
 tests/qemumonitortestutils.c | 12 ++++++++++--
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index 65694bab71..543b6cd17a 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -79,6 +79,7 @@ struct _qemuMonitor {
 
     unsigned json: 1;
     unsigned json_hmp: 1;
+    unsigned wait_greeting: 1;
 };
 
 static virClassPtr qemuMonitorClass;
@@ -365,6 +366,9 @@ qemuMonitorIOProcess(qemuMonitorPtr mon)
     if (len < 0)
         return -1;
 
+    if (len && mon->wait_greeting)
+        mon->wait_greeting = 0;
+
     if (len < mon->bufferOffset) {
         memmove(mon->buffer, mon->buffer + len, mon->bufferOffset - len);
         mon->bufferOffset -= len;
@@ -538,7 +542,8 @@ static void qemuMonitorUpdateWatch(qemuMonitorPtr mon)
     if (mon->lastError.code == VIR_ERR_OK) {
         events |= VIR_EVENT_HANDLE_READABLE;
 
-        if (mon->msg && mon->msg->txOffset < mon->msg->txLength)
+        if ((mon->msg && mon->msg->txOffset < mon->msg->txLength) &&
+            !mon->wait_greeting)
             events |= VIR_EVENT_HANDLE_WRITABLE;
     }
 
@@ -718,6 +723,8 @@ qemuMonitorOpenInternal(virDomainObjPtr vm,
     mon->hasSendFD = hasSendFD;
     mon->vm = vm;
     mon->json = json;
+    if (json)
+        mon->wait_greeting = 1;
     mon->cb = cb;
     qemuMonitorLock(mon);
 
diff --git a/tests/qemumonitortestutils.c b/tests/qemumonitortestutils.c
index 76b11e6775..fcf8663152 100644
--- a/tests/qemumonitortestutils.c
+++ b/tests/qemumonitortestutils.c
@@ -418,6 +418,9 @@ static qemuMonitorCallbacks qemuCallbacks = {
     .errorNotify = qemuMonitorTestErrorNotify,
 };
 
+#define QEMU_JSON_GREETING "{\"QMP\": {\"version\": {\"qemu\": {\"micro\": 1, \"minor\": 0, \"major\": 1}, \"package\": \" (qemu-kvm-1.0.1)\"}, \"capabilities\": []}}"
+#define QEMU_TEXT_GREETING "QEMU 1.0,1 monitor - type 'help' for more information"
+
 qemuMonitorTestPtr qemuMonitorTestNew(bool json, virCapsPtr caps)
 {
     qemuMonitorTestPtr test;
@@ -458,7 +461,7 @@ qemuMonitorTestPtr qemuMonitorTestNew(bool json, virCapsPtr caps)
 
     if (!(test->mon = qemuMonitorOpen(test->vm,
                                       &src,
-                                      true,
+                                      json ? 1 : 0,
                                       &qemuCallbacks)))
         goto error;
     qemuMonitorLock(test->mon);
@@ -468,8 +471,13 @@ qemuMonitorTestPtr qemuMonitorTestNew(bool json, virCapsPtr caps)
     if (!test->client)
         goto error;
 
+    if (qemuMonitorTestAddReponse(test, json ?
+                                  QEMU_JSON_GREETING :
+                                  QEMU_TEXT_GREETING) < 0)
+        goto error;
+
     if (virNetSocketAddIOCallback(test->client,
-                                  VIR_EVENT_HANDLE_READABLE,
+                                  VIR_EVENT_HANDLE_WRITABLE,
                                   qemuMonitorTestIO,
                                   test,
                                   NULL) < 0)
-- 
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