On Tue, Oct 22, 2024 at 10:33:43AM +0100, Richard W.M. Jones wrote:
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@redhat.com> --- 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?
No, for some reason in our test code we replace the literal string "ABS_SRCDIR" without the common markers. I guess it was unique enough, in practice, for tests.
Anyway the series looks good, so:
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
I can't remember which (of probably many) bugs this relates to, but maybe one should be mentioned in the commit.
It was something that libguestfs hit back in august IIRC but I couldn't find the details. 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 :|