From: Peter Krempa <pkrempa@redhat.com>
'libxml2' deprecated the 'xmlIndentTreeOutput' thread-local variable as
well as the 'xmlThrDefIndentTreeOutput' function for setting the global
default, which we use in our code for formatting the metadata sub-XML.
'libxml2' also for now doesn't provide a way to set target indentation
level in 'xmlSaveCtxt' which would allow us to use the modern output
APIs, we can't replace our use of 'xmlDumpNode'.
Since the indentation is enabled by default in libxml2 and most of our
code using xmlDumpNode (notably except for the 'test' driver and
embedded qemu driver uses) is in standalone processes, which didn't
change the default, just removing the override will result in identical
behaviour.
For the two exeptions, the result of changing the default would be that
the <metadata> part would be un-indented, but that is still valid XML.
Thus to fix the deprecated use just stop setting 'xmlIndentTreeOutput'.
Closes: https://gitlab.com/libvirt/libvirt/-/issues/816
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
---
src/util/virxml.c | 10 ----------
1 file changed, 10 deletions(-)
diff --git a/src/util/virxml.c b/src/util/virxml.c
index 44f11accf3..77c7b5a8f4 100644
--- a/src/util/virxml.c
+++ b/src/util/virxml.c
@@ -1920,23 +1920,14 @@ virXMLFormatMetadata(virBuffer *buf,
{
g_autoptr(xmlBuffer) xmlbuf = NULL;
const char *xmlbufContent = NULL;
- int oldIndentTreeOutput = xmlIndentTreeOutput;
if (!metadata)
return 0;
- /* Indentation on output requires that we previously set
- * xmlKeepBlanksDefault to 0 when parsing; also, libxml does 2
- * spaces per level of indentation of intermediate elements,
- * but no leading indentation before the starting element.
- * Thankfully, libxml maps what looks like globals into
- * thread-local uses, so we are thread-safe. */
- xmlIndentTreeOutput = 1;
xmlbuf = virXMLBufferCreate();
if (xmlNodeDump(xmlbuf, metadata->doc, metadata,
virBufferGetIndent(buf) / 2, 1) < 0) {
- xmlIndentTreeOutput = oldIndentTreeOutput;
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("Unable to format metadata element"));
return -1;
@@ -1948,7 +1939,6 @@ virXMLFormatMetadata(virBuffer *buf,
virSkipSpaces(&xmlbufContent);
virBufferAsprintf(buf, "%s\n", xmlbufContent);
- xmlIndentTreeOutput = oldIndentTreeOutput;
return 0;
}
--
2.51.1On 11/10/25 17:20, Peter Krempa via Devel wrote:
> From: Peter Krempa <pkrempa@redhat.com>
>
> 'libxml2' deprecated the 'xmlIndentTreeOutput' thread-local variable as
> well as the 'xmlThrDefIndentTreeOutput' function for setting the global
> default, which we use in our code for formatting the metadata sub-XML.
>
> 'libxml2' also for now doesn't provide a way to set target indentation
> level in 'xmlSaveCtxt' which would allow us to use the modern output
> APIs, we can't replace our use of 'xmlDumpNode'.
Here, I'd like a reference to:
https://gitlab.gnome.org/GNOME/libxml2/-/issues/989
>
> Since the indentation is enabled by default in libxml2 and most of our
> code using xmlDumpNode (notably except for the 'test' driver and
> embedded qemu driver uses) is in standalone processes, which didn't
> change the default, just removing the override will result in identical
> behaviour.
I think there are more drivers like that: ESX, VMWare, hyperv and maybe
others.
>
> For the two exeptions, the result of changing the default would be that
exceptions
> the <metadata> part would be un-indented, but that is still valid XML.
Agreed. Once the aforementioned issue is fixed this can be switched to
xmlSaveTree().
>
> Thus to fix the deprecated use just stop setting 'xmlIndentTreeOutput'.
>
> Closes: https://gitlab.com/libvirt/libvirt/-/issues/816
> Signed-off-by: Peter Krempa <pkrempa@redhat.com>
> ---
> src/util/virxml.c | 10 ----------
> 1 file changed, 10 deletions(-)
>
> diff --git a/src/util/virxml.c b/src/util/virxml.c
> index 44f11accf3..77c7b5a8f4 100644
> --- a/src/util/virxml.c
> +++ b/src/util/virxml.c
> @@ -1920,23 +1920,14 @@ virXMLFormatMetadata(virBuffer *buf,
> {
> g_autoptr(xmlBuffer) xmlbuf = NULL;
> const char *xmlbufContent = NULL;
> - int oldIndentTreeOutput = xmlIndentTreeOutput;
>
> if (!metadata)
> return 0;
>
> - /* Indentation on output requires that we previously set
> - * xmlKeepBlanksDefault to 0 when parsing; also, libxml does 2
> - * spaces per level of indentation of intermediate elements,
> - * but no leading indentation before the starting element.
> - * Thankfully, libxml maps what looks like globals into
> - * thread-local uses, so we are thread-safe. */
> - xmlIndentTreeOutput = 1;
> xmlbuf = virXMLBufferCreate();
>
> if (xmlNodeDump(xmlbuf, metadata->doc, metadata,
> virBufferGetIndent(buf) / 2, 1) < 0) {
> - xmlIndentTreeOutput = oldIndentTreeOutput;
> virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> _("Unable to format metadata element"));
> return -1;
> @@ -1948,7 +1939,6 @@ virXMLFormatMetadata(virBuffer *buf,
> virSkipSpaces(&xmlbufContent);
>
> virBufferAsprintf(buf, "%s\n", xmlbufContent);
> - xmlIndentTreeOutput = oldIndentTreeOutput;
>
> return 0;
> }
Michal
On Tue, Nov 11, 2025 at 09:35:59AM +0100, Michal Prívozník via Devel wrote: > On 11/10/25 17:20, Peter Krempa via Devel wrote: > > From: Peter Krempa <pkrempa@redhat.com> > > > > 'libxml2' deprecated the 'xmlIndentTreeOutput' thread-local variable as > > well as the 'xmlThrDefIndentTreeOutput' function for setting the global > > default, which we use in our code for formatting the metadata sub-XML. > > > > 'libxml2' also for now doesn't provide a way to set target indentation > > level in 'xmlSaveCtxt' which would allow us to use the modern output > > APIs, we can't replace our use of 'xmlDumpNode'. > > Here, I'd like a reference to: > > https://gitlab.gnome.org/GNOME/libxml2/-/issues/989 > > > > > Since the indentation is enabled by default in libxml2 and most of our > > code using xmlDumpNode (notably except for the 'test' driver and > > embedded qemu driver uses) is in standalone processes, which didn't > > change the default, just removing the override will result in identical > > behaviour. > > I think there are more drivers like that: ESX, VMWare, hyperv and maybe > others. IIUC, this problem only affects drivers which support the metadata XML, and none of those wire up the metadata support. $ git grep 'domainSetMetadata =' src/bhyve/bhyve_driver.c: .domainSetMetadata = bhyveDomainSetMetadata, /* 1.2.4 */ src/libxl/libxl_driver.c: .domainSetMetadata = libxlDomainSetMetadata, /* 5.7.0 */ src/lxc/lxc_driver.c: .domainSetMetadata = lxcDomainSetMetadata, /* 1.1.3 */ src/qemu/qemu_driver.c: .domainSetMetadata = qemuDomainSetMetadata, /* 0.9.10 */ src/remote/remote_driver.c: .domainSetMetadata = remoteDomainSetMetadata, /* 0.9.10 */ src/test/test_driver.c: .domainSetMetadata = testDomainSetMetadata, /* 1.1.3 */ With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On Tue, Nov 11, 2025 at 09:35:59 +0100, Michal Prívozník wrote:
> On 11/10/25 17:20, Peter Krempa via Devel wrote:
> > From: Peter Krempa <pkrempa@redhat.com>
> >
> > 'libxml2' deprecated the 'xmlIndentTreeOutput' thread-local variable as
> > well as the 'xmlThrDefIndentTreeOutput' function for setting the global
> > default, which we use in our code for formatting the metadata sub-XML.
> >
> > 'libxml2' also for now doesn't provide a way to set target indentation
> > level in 'xmlSaveCtxt' which would allow us to use the modern output
> > APIs, we can't replace our use of 'xmlDumpNode'.
>
> Here, I'd like a reference to:
>
> https://gitlab.gnome.org/GNOME/libxml2/-/issues/989
I'll add:
(See https://gitlab.gnome.org/GNOME/libxml2/-/issues/989)
on the next line.
> >
> > Since the indentation is enabled by default in libxml2 and most of our
> > code using xmlDumpNode (notably except for the 'test' driver and
> > embedded qemu driver uses) is in standalone processes, which didn't
> > change the default, just removing the override will result in identical
> > behaviour.
>
> I think there are more drivers like that: ESX, VMWare, hyperv and maybe
> others.
>
> >
> > For the two exeptions, the result of changing the default would be that
>
> exceptions
How about avoiding the issue by not naming anything:
Since the indentation is enabled by default in libxml2 and our most
commonly used code which calls xmlDumpNode lives in a standalone
process, where we don't override the setting, just removing the
override will result in identical behaviour.
For the use cases which do live in a process we don't fully control and
thus the default could have been overriden, the result would be that
the <metadata> element would be un-indented, but that is still valid XML.
> Agreed. Once the aforementioned issue is fixed this can be switched to
> xmlSaveTree().
>
> >
> > Thus to fix the deprecated use just stop setting 'xmlIndentTreeOutput'.
> >
> > Closes: https://gitlab.com/libvirt/libvirt/-/issues/816
> > Signed-off-by: Peter Krempa <pkrempa@redhat.com>
> > ---
> > src/util/virxml.c | 10 ----------
> > 1 file changed, 10 deletions(-)
> >
> > diff --git a/src/util/virxml.c b/src/util/virxml.c
> > index 44f11accf3..77c7b5a8f4 100644
> > --- a/src/util/virxml.c
> > +++ b/src/util/virxml.c
> > @@ -1920,23 +1920,14 @@ virXMLFormatMetadata(virBuffer *buf,
> > {
> > g_autoptr(xmlBuffer) xmlbuf = NULL;
> > const char *xmlbufContent = NULL;
> > - int oldIndentTreeOutput = xmlIndentTreeOutput;
> >
> > if (!metadata)
> > return 0;
> >
> > - /* Indentation on output requires that we previously set
> > - * xmlKeepBlanksDefault to 0 when parsing; also, libxml does 2
> > - * spaces per level of indentation of intermediate elements,
> > - * but no leading indentation before the starting element.
> > - * Thankfully, libxml maps what looks like globals into
> > - * thread-local uses, so we are thread-safe. */
> > - xmlIndentTreeOutput = 1;
> > xmlbuf = virXMLBufferCreate();
> >
> > if (xmlNodeDump(xmlbuf, metadata->doc, metadata,
> > virBufferGetIndent(buf) / 2, 1) < 0) {
> > - xmlIndentTreeOutput = oldIndentTreeOutput;
> > virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> > _("Unable to format metadata element"));
> > return -1;
> > @@ -1948,7 +1939,6 @@ virXMLFormatMetadata(virBuffer *buf,
> > virSkipSpaces(&xmlbufContent);
> >
> > virBufferAsprintf(buf, "%s\n", xmlbufContent);
> > - xmlIndentTreeOutput = oldIndentTreeOutput;
> >
> > return 0;
> > }
>
>
> Michal
>
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