[libvirt] [PATCH 08/10] qemu: Add ability to abort existing console while creating new one

[Peter Krempa]

This patch fixes console corruption, that happens if two concurrent
sessions are opened for a single console on a domain. Result of this
corruption was, that each of the console streams did recieve just a part
of the data written to the pipe so every console rendered unusable.

This patch adds a check that verifies if an open console exists and
notifies the user. This patch also adds support for the flag
VIR_DOMAIN_CONSOLE_FORCE that interrupts the existing session before
creating a new one. This serves as a fallback if an AFK admin holds the
console or a connection breaks.
---
 src/qemu/qemu_domain.c |    3 +++
 src/qemu/qemu_domain.h |    2 ++
 src/qemu/qemu_driver.c |   23 ++++++++++++++++++++++-
 3 files changed, 27 insertions(+), 1 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 85bebd6..be316b6 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -233,6 +233,9 @@ static void qemuDomainObjPrivateFree(void *data)
     VIR_FREE(priv->lockState);
     VIR_FREE(priv->origname);

+    if (priv->console)
+        virStreamFree(priv->console);
+
     /* This should never be non-NULL if we get here, but just in case... */
     if (priv->mon) {
         VIR_ERROR(_("Unexpected QEMU monitor still active during domain deletion"));
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index d9f323c..e32f4ef 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -127,6 +127,8 @@ struct _qemuDomainObjPrivate {

     unsigned long migMaxBandwidth;
     char *origname;
+
+    virStreamPtr console;
 };

 struct qemuDomainWatchdogEvent
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index ec01cd5..3b0cb70 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -10394,8 +10394,10 @@ qemuDomainOpenConsole(virDomainPtr dom,
     int ret = -1;
     int i;
     virDomainChrDefPtr chr = NULL;
+    qemuDomainObjPrivatePtr priv;

-    virCheckFlags(0, -1);
+    virCheckFlags(VIR_DOMAIN_CONSOLE_TRY |
+                  VIR_DOMAIN_CONSOLE_FORCE, -1);

     qemuDriverLock(driver);
     virUUIDFormat(dom->uuid, uuidstr);
@@ -10412,6 +10414,8 @@ qemuDomainOpenConsole(virDomainPtr dom,
         goto cleanup;
     }

+    priv = vm->privateData;
+
     if (dev_name) {
         if (vm->def->console &&
             STREQ(dev_name, vm->def->console->info.alias))
@@ -10445,10 +10449,27 @@ qemuDomainOpenConsole(virDomainPtr dom,
         goto cleanup;
     }

+    /* kill open console stream */
+    if (priv->console) {
+        if (virFDStreamIsOpen(priv->console) &&
+            !(flags & VIR_DOMAIN_CONSOLE_FORCE)) {
+            qemuReportError(VIR_ERR_OPERATION_FAILED,
+                            _("Active console session exists for this domain"));
+            goto cleanup;
+        }
+
+        virStreamAbort(priv->console);
+        virStreamFree(priv->console);
+        priv->console = NULL;
+    }
+
     if (virFDStreamOpenFile(st, chr->source.data.file.path,
                             0, 0, O_RDWR) < 0)
         goto cleanup;

+    virStreamRef(st);
+    priv->console = st;
+
     ret = 0;
 cleanup:
     if (vm)
-- 
1.7.3.4