On Tue, Oct 22, 2024 at 10:27:54AM +0100, Daniel P. Berrangé wrote:
> Libxml2 has awful error reporting behaviour when reading files. When
> we fail to load a file from the test driver we see:
>
> $ virsh -c test:///wibble.xml
> I/O warning : failed to load external entity "/wibble.xml"
> error: failed to connect to the hypervisor
> error: XML error: failed to parse xml document '/wibble.xml'
>
> where the I/O warning line is something printed by libxml2 itself,
> which also lacks any useful detail.
>
> Switching to our own file reading code we can massively improve
> things:
>
> $ ./build/tools/virsh -c test:///wibble.xml
> error: failed to connect to the hypervisor
> error: Failed to open file '/wibble.xml': No such file or directory
>
> Using 10 MB as an upper limit on XML file size ought to be sufficient
> for any XML files libvirt is reading.
>
> Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
> ---
> src/util/virxml.c | 8 +++++---
> tests/qemuxmlconfdata/nonexistent-file.x86_64-latest.err | 2 +-
> 2 files changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/src/util/virxml.c b/src/util/virxml.c
> index 797aa6f6ca..deed258bb0 100644
> --- a/src/util/virxml.c
> +++ b/src/util/virxml.c
> @@ -1142,6 +1142,7 @@ virXMLParseHelper(int domcode,
> xmlNodePtr rootnode;
> const char *docname;
> int parseFlags = XML_PARSE_NONET | XML_PARSE_NOWARNING;
> + g_autofree char *xmlStrPtr = NULL;
>
> if (filename)
> docname = filename;
> @@ -1165,10 +1166,11 @@ virXMLParseHelper(int domcode,
> }
>
> if (filename) {
> - xml = xmlCtxtReadFile(pctxt, filename, NULL, parseFlags);
> - } else {
> - xml = xmlCtxtReadDoc(pctxt, BAD_CAST xmlStr, url, NULL, parseFlags);
> + if (virFileReadAll(filename, 1024*1024*10, &xmlStrPtr) < 0)
> + return NULL;
> + xmlStr = xmlStrPtr;
> }
> + xml = xmlCtxtReadDoc(pctxt, BAD_CAST xmlStr, url, NULL, parseFlags);
>
> if (!xml) {
> if (virGetLastErrorCode() == VIR_ERR_OK) {
> diff --git a/tests/qemuxmlconfdata/nonexistent-file.x86_64-latest.err b/tests/qemuxmlconfdata/nonexistent-file.x86_64-latest.err
> index 0ddf1ea510..2aedf3eded 100644
> --- a/tests/qemuxmlconfdata/nonexistent-file.x86_64-latest.err
> +++ b/tests/qemuxmlconfdata/nonexistent-file.x86_64-latest.err
> @@ -1 +1 @@
> -XML error: failed to parse xml document 'ABS_SRCDIR/qemuxmlconfdata/nonexistent-file.xml'
> +Failed to open file 'ABS_SRCDIR/qemuxmlconfdata/nonexistent-file.xml': No such file or directory
I know it doesn't matter as the file is literally not there, but isn't
that supposed to be @ABS_SRCDIR@ or similar?
Anyway the series looks good, so:
Reviewed-by: Richard W.M. Jones <rjones@xxxxxxxxxx>
I can't remember which (of probably many) bugs this relates to, but
maybe one should be mentioned in the commit.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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