virsh: add snapshot-create-as memspec support

External checkpoints could be created with snapshot-create, but
without libvirt supplying a default name for the memory file,
it is essential to add a new argument to snapshot-create-as to
allow the user to choose the memory file name.  This adds the
option --memspec [file=]name[,snapshot=type], where type can
be none, internal, or external.  For an example,

virsh snapshot-create-as $dom --memspec /path/to/file

is the shortest possible command line for creating an external
checkpoint, named after the current timestamp.

* tools/virsh-snapshot.c (vshParseSnapshotMemspec): New function.
(cmdSnapshotCreateAs): Use it.
* tests/virsh-optparse (test_url): Test it.
* tools/virsh.pod (snapshot-create-as): Document it.

tests/virsh-optparse

@@ -1,7 +1,7 @@
 #!/bin/sh
 # Ensure that virsh option parsing doesn't regress
 
-# Copyright (C) 2011 Red Hat, Inc.
+# Copyright (C) 2011-2012 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
@@ -73,6 +73,7 @@ done
 cat <<\EOF > exp-out || framework_failure
 <domainsnapshot>
   <description>1&lt;2</description>
+  <memory file='d,e'/>
   <disks>
     <disk name='vda' snapshot='external'>
       <source file='a&amp;b,c'/>
@@ -84,7 +85,7 @@ cat <<\EOF > exp-out || framework_failure
 EOF
 virsh -q -c $test_url snapshot-create-as --print-xml test \
   --diskspec 'vda,file=a&b,,c,snapshot=external' --description '1<2' \
-  --diskspec vdb >out 2>>err || fail=1
+  --diskspec vdb --memspec file=d,,e >out 2>>err || fail=1
 compare exp-out out || fail=1
 
 cat <<\EOF > exp-out || framework_failure

tools/virsh-snapshot.c

@@ -193,6 +193,49 @@ cleanup:
 /*
  * "snapshot-create-as" command
  */
+static int
+vshParseSnapshotMemspec(vshControl *ctl, virBufferPtr buf, const char *str)
+{
+    int ret = -1;
+    const char *snapshot = NULL;
+    const char *file = NULL;
+    char **array = NULL;
+    int narray;
+    int i;
+
+    if (!str)
+        return 0;
+
+    narray = vshStringToArray(str, &array);
+    if (narray < 0)
+        goto cleanup;
+
+    for (i = 0; i < narray; i++) {
+        if (!snapshot && STRPREFIX(array[i], "snapshot="))
+            snapshot = array[i] + strlen("snapshot=");
+        else if (!file && STRPREFIX(array[i], "file="))
+            file = array[i] + strlen("file=");
+        else if (!file && *array[i] == '/')
+            file = array[i];
+        else
+            goto cleanup;
+    }
+
+    virBufferAddLit(buf, "  <memory");
+    virBufferEscapeString(buf, " snapshot='%s'", snapshot);
+    virBufferEscapeString(buf, " file='%s'", file);
+    virBufferAddLit(buf, "/>\n");
+    ret = 0;
+cleanup:
+    if (ret < 0)
+        vshError(ctl, _("unable to parse memspec: %s"), str);
+    if (array) {
+        VIR_FREE(*array);
+        VIR_FREE(array);
+    }
+    return ret;
+}
+
 static int
 vshParseSnapshotDiskspec(vshControl *ctl, virBufferPtr buf, const char *str)
 {
@@ -263,6 +306,8 @@ static const vshCmdOptDef opts_snapshot_create_as[] = {
     {"quiesce", VSH_OT_BOOL, 0, N_("quiesce guest's file systems")},
     {"atomic", VSH_OT_BOOL, 0, N_("require atomic operation")},
     {"live", VSH_OT_BOOL, 0, N_("take a live snapshot")},
+    {"memspec", VSH_OT_DATA, VSH_OFLAG_REQ_OPT,
+     N_("memory attributes: [file=]name[,snapshot=type]")},
     {"diskspec", VSH_OT_ARGV, 0,
      N_("disk attributes: disk[,snapshot=type][,driver=type][,file=name]")},
     {NULL, 0, 0, NULL}
@@ -276,6 +321,7 @@ cmdSnapshotCreateAs(vshControl *ctl, const vshCmd *cmd)
     char *buffer = NULL;
     const char *name = NULL;
     const char *desc = NULL;
+    const char *memspec = NULL;
     virBuffer buf = VIR_BUFFER_INITIALIZER;
     unsigned int flags = 0;
     const vshCmdOpt *opt = NULL;
@@ -310,6 +356,12 @@ cmdSnapshotCreateAs(vshControl *ctl, const vshCmd *cmd)
         virBufferEscapeString(&buf, "  <name>%s</name>\n", name);
     if (desc)
         virBufferEscapeString(&buf, "  <description>%s</description>\n", desc);
+
+    if (vshCommandOptString(cmd, "memspec", &memspec) < 0 ||
+        vshParseSnapshotMemspec(ctl, &buf, memspec) < 0) {
+        virBufferFreeAndReset(&buf);
+        goto cleanup;
+    }
     if (vshCommandOptBool(cmd, "diskspec")) {
         virBufferAddLit(&buf, "  <disks>\n");
         while ((opt = vshCommandOptArgv(cmd, opt))) {

tools/virsh.pod

@@ -2670,8 +2670,8 @@ by command such as B<destroy> or by internal guest action).
 
 =item B<snapshot-create-as> I<domain> {[I<--print-xml>]
 | [I<--no-metadata>] [I<--halt>] [I<--reuse-external>]} [I<name>]
-[I<description>] [I<--disk-only> [I<--quiesce>] [I<--atomic>]
+[I<description>] [I<--disk-only> [I<--quiesce>]] [I<--atomic>]
-[I<--live>] [[I<--diskspec>] B<diskspec>]...]
+[[I<--live>] [I<--memspec> B<memspec>]] [I<--diskspec>] B<diskspec>]...
 
 Create a snapshot for domain I<domain> with the given <name> and
 <description>; if either value is omitted, libvirt will choose a
@@ -2681,9 +2681,16 @@ Otherwise, if I<--halt> is specified, the domain will be left in an
 inactive state after the snapshot is created, and if I<--disk-only>
 is specified, the snapshot will not include vm state.
 
-The I<--disk-only> flag is used to request a disk-only snapshot.  When
+The I<--memspec> option can be used to control whether a checkpoint
-this flag is in use, the command can also take additional I<diskspec>
+is internal or external.  The I<--memspec> flag is mandatory, followed
-arguments to add <disk> elements to the xml.  Each <diskspec> is in the
+by a B<memspec> of the form B<[file=]name[,snapshot=type]>, where
+type can be B<none>, B<internal>, or B<external>.  To include a literal
+comma in B<file=name>, escape it with a second comma.
+
+The I<--diskspec> option can be used to control how I<--disk-only> and
+external checkpoints create external files.  This option can occur
+multiple times, according to the number of <disk> elements in the domain
+xml.  Each <diskspec> is in the
 form B<disk[,snapshot=type][,driver=type][,file=name]>.  To include a
 literal comma in B<disk> or in B<file=name>, escape it with a second
 comma.  A literal I<--diskspec> must precede each B<diskspec> unless