Re: [PATCH v2 3/3] util/xml: open XML files before calling libxml2

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(a)redhat.com&gt; --- 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