[libvirt] Libvirt config converter can't handle file not ending with new line

[Jim Fehlig]

On 11/07/2017 08:54 AM, Wim ten Have wrote:
> On Tue, 7 Nov 2017 12:20:05 +0000
> Wei Liu <wei.liu2 at citrix.com> wrote:
> 
>> On Mon, Nov 06, 2017 at 09:41:01PM -0700, Jim Fehlig wrote:
>>> On 10/30/2017 06:17 AM, Wei Liu wrote:
>>>> Hi Jim
>>>>
>>>> I discover a problem when using xen_xl converter. When the file in
>>>> question doesn't end with a new line, I get the following error:
>>>>
>>>>     error: configuration file syntax error: memory conf:53: expecting a value
>>>
>>> I'm not able to reproduce this issue. The libvirt.git tree I tried was a bit
>>> dated, but even after updating to latest master I can't reproduce.
>>>    
>>>> After digging a bit (but haven't read libvirt code), it appears that the
>>>> file didn't end with a new line.
>>>
>>> I tried several files without ending new lines, going both directions
>>> (domxml-to-native and domxml-from-native), but didn't see the mentioned
>>> error. Perhaps your config is revealing another bug which is being
>>> improperly reported. Can you provide an example of the problematic config?
>>>    
>>
>> I tried to get the exact file that caused the problem but it is already
>> destroyed by osstest.
>>
>> A similar file:
>>
>> http://logs.test-lab.xenproject.org/osstest/logs/115436/test-amd64-amd64-libvirt-pair/debian.guest.osstest.cfg
>>
>> If you hexdump -C it, you can see the last character is 0a. Remove it and
>> feed the file into the converter.
>> Wei.
> 
>    The phenonomem you point out is indeed weird.  And my first response
>    is that this is a bug parsing the cfg input.  I did little explore and
>    think that src/util/virconf.c (virConfParseLong(), virConfParseValue())
>    should be reworked as pointed out in below context diffs.
> 
> 	<wtenhave at nina:140> git diff
> 	diff --git a/src/util/virconf.c b/src/util/virconf.c
> 	index 39c2bd917..bc8e57ec3 100644
> 	--- a/src/util/virconf.c
> 	+++ b/src/util/virconf.c
> 	@@ -352,7 +352,7 @@ virConfParseLong(virConfParserCtxtPtr ctxt, long long *val)
> 	     } else if (CUR == '+') {
> 	         NEXT;
> 	     }
> 	-    if ((ctxt->cur >= ctxt->end) || (!c_isdigit(CUR))) {
> 	+    if ((ctxt->cur > ctxt->end) || (!c_isdigit(CUR))) {
> 	         virConfError(ctxt, VIR_ERR_CONF_SYNTAX, _("unterminated number"));
> 	         return -1;
> 	     }
> 	@@ -456,7 +456,7 @@ virConfParseValue(virConfParserCtxtPtr ctxt)
> 	     long long l = 0;
> 	
> 	     SKIP_BLANKS;
> 	-    if (ctxt->cur >= ctxt->end) {
> 	+    if (ctxt->cur > ctxt->end) {
> 	         virConfError(ctxt, VIR_ERR_CONF_SYNTAX, _("expecting a value"));
> 	         return NULL;
> 	     }
> 
>    I did not go beyond this yet.

Thanks Wim. I noticed Cole fixed a similar issue when parsing content from a 
file with commit 3cc2a9e0d4. But I think instead of replicating that fix in 
virConfReadString(), we should just set the end of content correctly in 
virConfParse(). I've sent a patch along those lines that fixes Wei's test case 
and doesn't regress Cole's test case

https://www.redhat.com/archives/libvir-list/2017-November/msg00286.html

Regards,
Jim