[libvirt] [PATCH] Improved error messages in XM conf module

[Daniel P. Berrange]

On Mon, Sep 15, 2008 at 04:06:46PM +0100, Richard W.M. Jones wrote:
> The attached patch improves error handling in the XM config file
> parser (src/conf.c).
> 
> Currently it has a custom error function called virConfError which has
> three problems.  Firstly the conf argument is ignored and therefore
> pointless to even pass.  Secondly the function takes a line number
> parameter (for reporting the line number where parsing failed), but
> this is swallowed and not printed in error messages.  Thirdly, and
> most importantly, the name of the file where the error occurs is not
> printed by default unless the caller happens to print it.
> 
> If there is an _empty_ file in /etc/xen we get this error:
> 
>   # virsh list --all
>   libvir: error : failed to read configuration file /etc/xen/foobar
> 
> but if the spurious file under /etc/xen is non-empty, like a script,
> you get completely anonymous errors such as:
> 
>   libvir: error : configuration file syntax error: expecting an assignment
> 
> or:
> 
>   libvir: error : configuration file syntax error: expecting a value
> 
> The patch fixes this by printing out the filename and line number if
> these are available from the parser context (and the parser context is
> passed to virConfError instead of the unused virConfPtr).  With this
> patch you'll get errors for the second case like this:
> 
>   # virsh list --inactive
>   libvir: error : /etc/xen/foobar:1: expecting a value

ACK, this has annoyed the hell out of me for ages.

Daniel
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