[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [Libvir] [PATCH] Allow virDomainDefine to overwrite existing inactive domains for xen 3.0.3 userspace installations



Hugh Brock wrote:
virDomainDefineXML should overwrite an existing inactive domain config if it finds one; it does this successfully for later (post 3.0.3) xen versions. However on xen 3.0.3 overwriting an existing config would fail with a name conflict. This patch allows the overwrite, removing the prior config from the config hashes.

If someone more familiar than I with libvirt error handling and style could look at this and tell me if I've done something horribly wrong, I'd appreciate it.

Signed-off-by: Hugh Brock <hbrock redhat com>

Thinking aloud and trying to untangle the various hashes used ...

Index: src/xm_internal.c
===================================================================
RCS file: /data/cvs/libvirt/src/xm_internal.c,v
retrieving revision 1.23
diff -u -r1.23 xm_internal.c
--- src/xm_internal.c	4 Apr 2007 14:19:49 -0000	1.23
+++ src/xm_internal.c	1 May 2007 17:23:05 -0000
@@ -2072,7 +2072,9 @@
  */
 virDomainPtr xenXMDomainDefineXML(virConnectPtr conn, const char *xml) {
     virDomainPtr ret;
+    virDomainPtr olddomain;
     char filename[PATH_MAX];
+    const char * oldfilename;
     unsigned char uuid[VIR_UUID_BUFLEN];
     virConfPtr conf = NULL;
     xenXMConfCachePtr entry = NULL;
@@ -2103,8 +2105,44 @@
     }
if (virHashLookup(nameConfigMap, value->str)) {
-        xenXMError(conn, VIR_ERR_INTERNAL_ERROR, "domain with name already exists");
-        goto error;
+        /* domain exists, we will overwrite it */
+
+        if (!(oldfilename = (char *)virHashLookup(nameConfigMap, value->str))) {
+            xenXMError(conn, VIR_ERR_INTERNAL_ERROR, "can't retrieve config filename for domain to overwrite");
+            goto error;
+        }

So get the filename from the nameConfigMap. Looks OK, although you could have also got the filename from configDir ++ "/" ++ value->str, but no matter.

+        if (!(entry = virHashLookup(configCache, oldfilename))) {
+            xenXMError(conn, VIR_ERR_INTERNAL_ERROR, "can't retrieve config entry for domain to overwrite");
+            goto error;
+        }

Get the xenXMConfCache object from the configCache keyed on filename. Looks OK.

Despite the name, configCache isn't literally a cache. Rather it's a list of filename -> config entries for everything under /etc/xen.

+        if (xenXMConfigGetUUID(entry->conf, "uuid", uuid) < 0) {
+            xenXMError(conn, VIR_ERR_INTERNAL_ERROR, "uuid config parameter is missing");
+            goto error;
+        }

Get the UUID from the config file.

+        if (!(olddomain = virGetDomain(conn, value->str, uuid)))
+            goto error;

Get the old domain, given name & UUID.

+        if (olddomain->id != -1) {
+            xenXMError(conn, VIR_ERR_INTERNAL_ERROR, "can't overwrite an active domain");
+            goto error;
+        }
+
+        /* Remove the name -> filename mapping */
+        if (virHashRemoveEntry(nameConfigMap, value->str, NULL) < 0) {
+            xenXMError(conn, VIR_ERR_INTERNAL_ERROR, "failed to remove old domain from config map");
+            goto error;
+        }

Remove the old mapping in nameConfigMap.

+        /* Remove the config record itself */
+        if (virHashRemoveEntry(configCache, oldfilename, xenXMConfigFree) < 0) {
+            xenXMError(conn, VIR_ERR_INTERNAL_ERROR, "failed to remove old domain from config map");
+            goto error;
+        }

Remove the configCache entry.

+        entry = NULL;
     }

     if ((strlen(configDir) + 1 + strlen(value->str) + 1) > PATH_MAX) {

and then drop through to virConfWriteFile which will blindly overwrite the file.

Looks A-OK to me!

Rich.

--
Emerging Technologies, Red Hat  http://et.redhat.com/~rjones/
64 Baker Street, London, W1U 7DF     Mobile: +44 7866 314 421

Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod
Street, Windsor, Berkshire, SL4 1TE, United Kingdom.
Registered in England and Wales under Company Registration No. 3798903
Directors: Michael Cunningham (USA), Charlie Peters (USA) and David
Owens (Ireland)

Attachment: smime.p7s
Description: S/MIME Cryptographic Signature


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]