[virt-tools-list] [vhostmd] add SIGPIPE handler and do_reconnect function

[Michael Trapp]

vhostmd has no signal handler for SIGPIPE and a restart of libvirtd results in a
stopped vhostmd. The root cause seems to be a UDS socket between vhostmd and
libvirtd which is closed by a libvirtd restart. In addition to the signal handler
the connection to libvirtd has to be opened again otherwise vhostmd can't read
any data from libvirtd and doesn't update the metrics.

---
 vhostmd/vhostmd.c   |  2 ++
 vhostmd/virt-util.c | 45 +++++++++++++++++++++++++++++++++++++++------
 2 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/vhostmd/vhostmd.c b/vhostmd/vhostmd.c
index 7f04705..4cf4630 100644
--- a/vhostmd/vhostmd.c
+++ b/vhostmd/vhostmd.c
@@ -117,6 +117,7 @@ static void sig_handler(int sig, siginfo_t *siginfo ATTRIBUTE_UNUSED,
       case SIGQUIT:
          down = 1;
          break;
+      case SIGPIPE:
       default:
          break;
    }
@@ -1053,6 +1054,7 @@ int main(int argc, char *argv[])
    sigaction(SIGINT, &sig_action, NULL);
    sigaction(SIGQUIT, &sig_action, NULL);
    sigaction(SIGTERM, &sig_action, NULL);
+   sigaction(SIGPIPE, &sig_action, NULL);
 
    xmlInitParser();
 
diff --git a/vhostmd/virt-util.c b/vhostmd/virt-util.c
index 1c31305..c76e224 100644
--- a/vhostmd/virt-util.c
+++ b/vhostmd/virt-util.c
@@ -44,17 +44,47 @@ do_connect (void)
     return 0;
 }
 
+static int
+do_reconnect(void)
+{
+    if (conn != NULL)
+	virConnectClose (conn);
+
+    conn = virConnectOpenReadOnly (libvirt_uri);
+    if (conn == NULL) {
+	vu_log (VHOSTMD_ERR, "Unable to open libvirt connection to %s",
+		libvirt_uri ? libvirt_uri : "default hypervisor");
+	return -1;
+    }
+    return 0;
+}
+
 int vu_num_vms(void)
 {
+   int rc;
+
    if (do_connect () == -1) return -1;
+
+   rc = virConnectNumOfDomains(conn);
+   if (rc < 0) {
+	if (do_reconnect()) return -1;
    return virConnectNumOfDomains(conn);
+   }
+   return rc;
 }
 
 int vu_get_vms(int *ids, int max_ids)
 {
-   if (do_connect () == -1) return -1;
+   int rc;
+
+   if (do_connect() == -1) return -1;
    
-   return (virConnectListDomains(conn, ids, max_ids));
+   rc = virConnectListDomains(conn, ids, max_ids);
+   if (rc < 0) {
+      if (do_reconnect()) return -1;
+      return virConnectListDomains(conn, ids, max_ids);
+   }
+   return rc;
 }
 
 vu_vm *vu_get_vm(int id)
@@ -74,8 +104,11 @@ vu_vm *vu_get_vm(int id)
    
    dom = virDomainLookupByID(conn, id);
    if (dom == NULL) {
-       vu_log(VHOSTMD_ERR, "Failed to lookup domain for id %d", id);
-       goto error;
+      if (do_reconnect() ||
+          (dom = virDomainLookupByID(conn, id)) == NULL) {
+         vu_log(VHOSTMD_ERR, "Failed to lookup domain for id %d", id);
+         goto error;
+      }
    }
 
    uuid[0] = '\0';
@@ -98,8 +131,8 @@ vu_vm *vu_get_vm(int id)
 void vu_vm_free(vu_vm *vm)
 {
    if (vm) {
-      free(vm->name);
-      free(vm->uuid);
+      if (vm->name) free(vm->name);
+      if (vm->uuid) free(vm->uuid);
       free(vm);
    }
 }
-- 
2.12.3