[Libguestfs] [PATCH 6/8 v2 DISCUSSION ONLY] Add guestfs_add_domain 'live' flag.
Richard W.M. Jones
rjones at redhat.com
Fri Jan 28 19:38:35 UTC 2011
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
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>From 59d06155bf48f6656e5bc75dba99fc2b34515919 Mon Sep 17 00:00:00 2001
From: Richard W.M. Jones <rjones at redhat.com>
Date: Fri, 28 Jan 2011 13:19:52 +0000
Subject: [PATCH 6/8] Add guestfs_add_domain 'live' flag.
This optional flag controls whether this API call will try to connect
to a running virtual machine 'guestfsd' process.
If the flag is given and the virtual machine is running, then the
libvirt XML is parsed looking for a suitable <channel> element, and
'guestfs_set_attach_method' is called with the corresponding
virtio-serial socket path.
---
fish/fish.c | 2 +-
generator/generator_actions.ml | 18 +++-
src/virt.c | 192 ++++++++++++++++++++++++++++++++++-----
3 files changed, 183 insertions(+), 29 deletions(-)
diff --git a/fish/fish.c b/fish/fish.c
index 10f645f..eb7c8fe 100644
--- a/fish/fish.c
+++ b/fish/fish.c
@@ -1,5 +1,5 @@
/* guestfish - the filesystem interactive shell
- * Copyright (C) 2009-2010 Red Hat Inc.
+ * Copyright (C) 2009-2011 Red Hat Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
diff --git a/generator/generator_actions.ml b/generator/generator_actions.ml
index a2e7467..192df77 100644
--- a/generator/generator_actions.ml
+++ b/generator/generator_actions.ml
@@ -1074,7 +1074,7 @@ Please read L<guestfs(3)/INSPECTION> for more details.");
This returns the internal QEMU command line. 'debug' commands are
not part of the formal API and can be removed or changed at any time.");
- ("add_domain", (RInt "nrdisks", [String "dom"], [String "libvirturi"; Bool "readonly"; String "iface"]), -1, [FishAlias "domain"],
+ ("add_domain", (RInt "nrdisks", [String "dom"], [String "libvirturi"; Bool "readonly"; String "iface"; Bool "live"]), -1, [FishAlias "domain"],
[],
"add the disk(s) from a named libvirt domain",
"\
@@ -1101,12 +1101,18 @@ we connect to the default libvirt URI (or one set through an
environment variable, see the libvirt documentation for full
details).
+The optional C<live> flag controls whether this call will try
+to connect to a running virtual machine C<guestfsd> process if
+it sees a suitable E<lt>channelE<gt> element in the libvirt
+XML definition. The default (if the flag is omitted) is never
+to try.
+
The other optional parameters are passed directly through to
C<guestfs_add_drive_opts>.");
(*
This interface is not quite baked yet. -- RWMJ 2010-11-11
- ("add_libvirt_dom", (RInt "nrdisks", [Pointer ("virDomainPtr", "dom")], [Bool "readonly"; String "iface"]), -1, [NotInFish],
+ ("add_libvirt_dom", (RInt "nrdisks", [Pointer ("virDomainPtr", "dom")], [Bool "readonly"; String "iface"; Bool "live"]), -1, [NotInFish],
[],
"add the disk(s) from a libvirt domain",
"\
@@ -1129,7 +1135,13 @@ from a remote libvirt connection (see L<http://libvirt.org/remote.html>)
will fail unless those disks are accessible via the same device path
locally too.
-The optional parameters are passed directly through to
+The optional C<live> flag controls whether this call will try
+to connect to a running virtual machine C<guestfsd> process if
+it sees a suitable E<lt>channelE<gt> element in the libvirt
+XML definition. The default (if the flag is omitted) is never
+to try.
+
+The other optional parameters are passed directly through to
C<guestfs_add_drive_opts>.");
*)
diff --git a/src/virt.c b/src/virt.c
index 9f84908..4b66cc8 100644
--- a/src/virt.c
+++ b/src/virt.c
@@ -59,6 +59,8 @@ struct guestfs___add_libvirt_dom_argv {
int readonly;
#define GUESTFS___ADD_LIBVIRT_DOM_IFACE_BITMASK (UINT64_C(1)<<1)
const char *iface;
+#define GUESTFS___ADD_LIBVIRT_DOM_LIVE_BITMASK (UINT64_C(1)<<2)
+ int live;
};
static int guestfs___add_libvirt_dom (guestfs_h *g, virDomainPtr dom, const struct guestfs___add_libvirt_dom_argv *optargs);
@@ -73,6 +75,7 @@ guestfs__add_domain (guestfs_h *g, const char *domain_name,
int r = -1;
const char *libvirturi;
int readonly;
+ int live;
const char *iface;
struct guestfs___add_libvirt_dom_argv optargs2 = { .bitmask = 0 };
@@ -82,6 +85,13 @@ guestfs__add_domain (guestfs_h *g, const char *domain_name,
? optargs->readonly : 0;
iface = optargs->bitmask & GUESTFS_ADD_DOMAIN_IFACE_BITMASK
? optargs->iface : NULL;
+ live = optargs->bitmask & GUESTFS_ADD_DOMAIN_LIVE_BITMASK
+ ? optargs->live : 0;
+
+ if (live && readonly) {
+ error (g, _("you cannot set both live and readonly flags"));
+ return -1;
+ }
/* Connect to libvirt, find the domain. */
conn = virConnectOpenReadOnly (libvirturi);
@@ -108,6 +118,10 @@ guestfs__add_domain (guestfs_h *g, const char *domain_name,
optargs2.bitmask |= GUESTFS___ADD_LIBVIRT_DOM_IFACE_BITMASK;
optargs2.iface = iface;
}
+ if (live) {
+ optargs2.bitmask |= GUESTFS___ADD_LIBVIRT_DOM_LIVE_BITMASK;
+ optargs2.live = live;
+ }
r = guestfs___add_libvirt_dom (g, dom, &optargs2);
@@ -282,49 +296,63 @@ guestfs___for_each_disk (guestfs_h *g,
return r;
}
-static int
-add_disk (guestfs_h *g, const char *filename, const char *format,
- void *optargs_vp)
-{
- struct guestfs_add_drive_opts_argv *optargs = optargs_vp;
-
- if (format) {
- optargs->bitmask |= GUESTFS_ADD_DRIVE_OPTS_FORMAT_BITMASK;
- optargs->format = format;
- } else
- optargs->bitmask &= ~GUESTFS_ADD_DRIVE_OPTS_FORMAT_BITMASK;
+/* This was proposed as an external API, but it's not quite baked yet. */
- return guestfs__add_drive_opts (g, filename, optargs);
-}
+static int add_disk (guestfs_h *g, const char *filename, const char *format, void *optargs_vp);
+static int connect_live (guestfs_h *g, virDomainPtr dom);
-/* This was proposed as an external API, but it's not quite baked yet. */
static int
guestfs___add_libvirt_dom (guestfs_h *g, virDomainPtr dom,
const struct guestfs___add_libvirt_dom_argv *optargs)
{
- int r = -1;
- virErrorPtr err;
int cmdline_pos;
+ int r;
+ int readonly;
+ const char *iface;
+ int live;
- cmdline_pos = guestfs___checkpoint_cmdline (g);
-
- int readonly =
+ readonly =
optargs->bitmask & GUESTFS___ADD_LIBVIRT_DOM_READONLY_BITMASK
? optargs->readonly : 0;
- const char *iface =
+ iface =
optargs->bitmask & GUESTFS___ADD_LIBVIRT_DOM_IFACE_BITMASK
? optargs->iface : NULL;
+ live =
+ optargs->bitmask & GUESTFS___ADD_LIBVIRT_DOM_LIVE_BITMASK
+ ? optargs->live : 0;
+
+ if (live && readonly) {
+ error (g, _("you cannot set both live and readonly flags"));
+ return -1;
+ }
if (!readonly) {
virDomainInfo info;
+ virErrorPtr err;
+ int vm_running;
+
if (virDomainGetInfo (dom, &info) == -1) {
err = virGetLastError ();
error (g, _("error getting domain info: %s"), err->message);
- goto cleanup;
+ return -1;
}
- if (info.state != VIR_DOMAIN_SHUTOFF) {
- error (g, _("error: domain is a live virtual machine.\nYou must use readonly access because write access to a running virtual machine\ncan cause disk corruption."));
- goto cleanup;
+ vm_running = info.state != VIR_DOMAIN_SHUTOFF;
+
+ if (vm_running) {
+ /* If the caller specified the 'live' flag, then they want us to
+ * try to connect to guestfsd if the domain is running. Note
+ * that live readonly connections are not possible.
+ */
+ if (live)
+ return connect_live (g, dom);
+
+ /* Dangerous to modify the disks of a running VM. */
+ error (g, _("error: domain is a live virtual machine.\n"
+ "Writing to the disks of a running virtual machine can cause disk corruption.\n"
+ "Either use read-only access, or if the guest is running the guestfsd daemon\n"
+ "specify live access. In most libguestfs tools these options are --ro or\n"
+ "--live respectively. Consult the documentation for further information."));
+ return -1;
}
}
@@ -339,10 +367,124 @@ guestfs___add_libvirt_dom (guestfs_h *g, virDomainPtr dom,
optargs2.iface = iface;
}
+ /* Checkpoint the command line around the operation so that either
+ * all disks are added or none are added.
+ */
+ cmdline_pos = guestfs___checkpoint_cmdline (g);
r = guestfs___for_each_disk (g, dom, add_disk, &optargs2);
+ if (r == -1)
+ guestfs___rollback_cmdline (g, cmdline_pos);
+
+ return r;
+}
+
+static int
+add_disk (guestfs_h *g, const char *filename, const char *format,
+ void *optargs_vp)
+{
+ struct guestfs_add_drive_opts_argv *optargs = optargs_vp;
+
+ if (format) {
+ optargs->bitmask |= GUESTFS_ADD_DRIVE_OPTS_FORMAT_BITMASK;
+ optargs->format = format;
+ } else
+ optargs->bitmask &= ~GUESTFS_ADD_DRIVE_OPTS_FORMAT_BITMASK;
+
+ return guestfs__add_drive_opts (g, filename, optargs);
+}
+
+static int
+connect_live (guestfs_h *g, virDomainPtr dom)
+{
+ int i, r = -1;
+ virErrorPtr err;
+ xmlDocPtr doc = NULL;
+ xmlXPathContextPtr xpathCtx = NULL;
+ xmlXPathObjectPtr xpathObj = NULL;
+ char *xml = NULL;
+ char *path = NULL;
+ char *attach_method = NULL;
+
+ /* Domain XML. */
+ xml = virDomainGetXMLDesc (dom, 0);
+
+ if (!xml) {
+ err = virGetLastError ();
+ error (g, _("error reading libvirt XML information: %s"),
+ err->message);
+ goto cleanup;
+ }
+
+ /* Parse XML to document. */
+ doc = xmlParseMemory (xml, strlen (xml));
+ if (doc == NULL) {
+ error (g, _("unable to parse XML information returned by libvirt"));
+ goto cleanup;
+ }
+
+ xpathCtx = xmlXPathNewContext (doc);
+ if (xpathCtx == NULL) {
+ error (g, _("unable to create new XPath context"));
+ goto cleanup;
+ }
+
+ /* This gives us a set of all the <channel> nodes related to the
+ * guestfsd virtio-serial channel.
+ */
+ xpathObj = xmlXPathEvalExpression (BAD_CAST
+ "//devices/channel[@type=\"unix\" and "
+ "./source/@mode=\"bind\" and "
+ "./source/@path and "
+ "./target/@type=\"virtio\" and "
+ "./target/@name=\"org.libguestfs.channel.0\"]",
+ xpathCtx);
+ if (xpathObj == NULL) {
+ error (g, _("unable to evaluate XPath expression"));
+ goto cleanup;
+ }
+
+ xmlNodeSetPtr nodes = xpathObj->nodesetval;
+ for (i = 0; i < nodes->nodeNr; ++i) {
+ xmlXPathObjectPtr xppath;
+
+ /* See note in function above. */
+ xpathCtx->node = nodes->nodeTab[i];
+
+ /* The path is in <source path=..> attribute. */
+ xppath = xmlXPathEvalExpression (BAD_CAST "./source/@path", xpathCtx);
+ if (xppath == NULL ||
+ xppath->nodesetval == NULL ||
+ xppath->nodesetval->nodeNr == 0) {
+ xmlXPathFreeObject (xppath);
+ continue; /* no type attribute, skip it */
+ }
+ assert (xppath->nodesetval->nodeTab[0]);
+ assert (xppath->nodesetval->nodeTab[0]->type == XML_ATTRIBUTE_NODE);
+ xmlAttrPtr attr = (xmlAttrPtr) xppath->nodesetval->nodeTab[0];
+ path = (char *) xmlNodeListGetString (doc, attr->children, 1);
+ xmlXPathFreeObject (xppath);
+ break;
+ }
+
+ if (path == NULL) {
+ error (g, _("this guest has no libvirt <channel> definition for guestfsd"));
+ goto cleanup;
+ }
+
+ /* Got a path. */
+ attach_method = safe_malloc (g, strlen (path) + 5 + 1);
+ strcpy (attach_method, "unix:");
+ strcat (attach_method, path);
+ r = guestfs_set_attach_method (g, attach_method);
cleanup:
- if (r == -1) guestfs___rollback_cmdline (g, cmdline_pos);
+ free (path);
+ free (attach_method);
+ free (xml);
+ if (xpathObj) xmlXPathFreeObject (xpathObj);
+ if (xpathCtx) xmlXPathFreeContext (xpathCtx);
+ if (doc) xmlFreeDoc (doc);
+
return r;
}
--
1.7.3.5
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