Re: [libvirt] [PATCH 1/4] xml: Add attribute to <description> element to hold a short note
On 01/13/2012 11:17 AM, Peter Krempa wrote:
This patch adds an optional attribute note="" to the
<description>
element in the domain XML. This attribute can hold a short note defined
by the user to ease the identification of domains. The note is limited
to 40 characters.
I'd go one step further, and reject newlines.
*docs/formatdomain.html.in
*docs/schemas/domaincommon.rng
- add schema grammar for the new element and documentation
*src/conf/domain_conf.c
*src/conf/domain_conf.h
- add field to hold the new attribute
- add code to parse and create XML with the new attribute
---
docs/formatdomain.html.in | 7 +++++--
docs/schemas/domaincommon.rng | 14 +++++++++++++-
src/conf/domain_conf.c | 27 +++++++++++++++++++++++++--
src/conf/domain_conf.h | 1 +
4 files changed, 44 insertions(+), 5 deletions(-)
@@ -58,7 +59,9 @@
<dd>The content of the <code>description</code> element provides
a
human readable description of the virtual machine. This data is not
used by libvirt in any way, it can contain any information the user
- wants. <span class="since">Since 0.7.2</span></dd>
+ wants. <span class="since">Since 0.7.2</span> The optional
attribute
+ <code>note</code> provides space for a shorter description.
+ <span class="since">Since 0.9.10</span></dd>
The end result has confusing punctuation. I'd suggest:
+ wants, <span class="since">since 0.7.2</span>. The optional
attribute
+ <code>note</code> provides space for a shorter description,
+ capped at 40 bytes and with no newline,
+ <span class="since">since 0.9.10</span>.</dd>
+++ b/docs/schemas/domaincommon.rng
@@ -10,7 +10,19 @@
-->
<define name="description">
<element name="description">
- <text/>
+ <optional>
+ <attribute name="note">
+ <data type="string"/>
We can make this enforce length restrictions:
<data type="string">
<param name='pattern'>[^\n]{0,40}</param>
</data>
+ </attribute>
+ </optional>
+ <choice>
+ <group>
+ <text/>
+ </group>
+ <group>
+ <empty/>
+ </group>
+ </choice>
No need for a <group> around a single element. This whole layout may
change if we go with an optional <title> instead of <description
note='...'>, but I'd almost rather see:
<element name='description'>
<choice>
<group>
<attribute name='note'>...</attribute>
<choice>
<text/>
<empty/>
</choice>
</group>
<text/>
</choice>
</element>
that is, you must have the attribute, or text, or both, but not
<description/> with neither.
+ /* Extract short description of domain (note) */
+ def->note = virXPathString("string(./description[1]/@note)", ctxt);
+ if (def->note) {
+ if (strchr(def->note, '\n')) {
+ virDomainReportError(VIR_ERR_XML_ERROR,
+ "%s", _("Note attribute can't contain
newlines"));
+ goto error;
+ }
+
+ if (strlen(def->note) > 40) {
This checks for bytes, not characters (some 40-character UTF-8 strings
can occupy well more than 100 bytes). I'm probably okay with a byte
limit, but hope we don't get complaints about someone unable to write a
single word of 12 characters in their favorite locale.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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