[Libvir] [PATCH] Allow virDomainDefine to overwrite existing inactive domains for xen 3.0.3 userspace installations
Richard W.M. Jones
rjones at redhat.com
Wed May 2 10:26:31 UTC 2007
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 at 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.
--
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