[PATCH 12/12] bhyve: acquire a pidfile in the driver root directory

[Daniel P. Berrangé <berrange@xxxxxxxxxx>]

When we allow multiple instances of the driver for the same user
account, using a separate root directory, we need to ensure mutual
exclusion. Use a pidfile to guarantee this.

In privileged libvirtd this ends up locking

   /var/run/libvirt/bhyve/driver.pid

In unprivileged libvirtd this ends up locking

  /run/user/$UID/libvirt/bhyve/run/driver.pid

NB, the latter can vary depending on $XDG_RUNTIME_DIR

Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
---
 src/bhyve/bhyve_driver.c | 9 +++++++++
 src/bhyve/bhyve_utils.h  | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/src/bhyve/bhyve_driver.c b/src/bhyve/bhyve_driver.c
index 4ce9ef0b95..cfcf4e1fba 100644
--- a/src/bhyve/bhyve_driver.c
+++ b/src/bhyve/bhyve_driver.c
@@ -43,6 +43,7 @@
 #include "virthread.h"
 #include "virlog.h"
 #include "virfile.h"
+#include "virpidfile.h"
 #include "virtypedparam.h"
 #include "virrandom.h"
 #include "virstring.h"
@@ -1203,6 +1204,9 @@ bhyveStateCleanup(void)
     virObjectUnref(bhyve_driver->config);
     virPortAllocatorRangeFree(bhyve_driver->remotePorts);
 
+    if (bhyve_driver->lockFD != -1)
+        virPidFileRelease(BHYVE_STATE_DIR, "driver", bhyve_driver->lockFD);
+
     virMutexDestroy(&bhyve_driver->lock);
     VIR_FREE(bhyve_driver);
 
@@ -1222,6 +1226,7 @@ bhyveStateInitialize(bool privileged,
     if (VIR_ALLOC(bhyve_driver) < 0)
         return -1;
 
+    bhyve_driver->lockFD = -1;
     if (virMutexInit(&bhyve_driver->lock) < 0) {
         VIR_FREE(bhyve_driver);
         return -1;
@@ -1274,6 +1279,10 @@ bhyveStateInitialize(bool privileged,
         goto cleanup;
     }
 
+    if ((bhyve_driver->lockFD =
+         virPidFileAcquire(BHYVE_STATE_DIR, "driver", true, getpid())) < 0)
+        goto cleanup;
+
     if (virDomainObjListLoadAllConfigs(bhyve_driver->domains,
                                        BHYVE_STATE_DIR,
                                        NULL, true,
diff --git a/src/bhyve/bhyve_utils.h b/src/bhyve/bhyve_utils.h
index 26956d7d21..3d212e3ccf 100644
--- a/src/bhyve/bhyve_utils.h
+++ b/src/bhyve/bhyve_utils.h
@@ -48,6 +48,9 @@ struct _bhyveConn {
 
     virBhyveDriverConfigPtr config;
 
+    /* pid file FD, ensures two copies of the driver can't use the same root */
+    int lockFD;
+
     virDomainObjListPtr domains;
     virCapsPtr caps;
     virDomainXMLOptionPtr xmlopt;
-- 
2.21.0

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