[Libvir] Cleanup patch

[Richard W.M. Jones]

Daniel Veillard wrote:
>  Enclosed is a cleanup patch I applied, it corrects the XML api generation,
> fixes warning in the XSLT stylesheet, add comments to a number of internal
> functions, makes most function of the QEmu back-end static, fixes a few bugs
> found in the way.

Looks fine, except my general grumble below.

> @@ -113,12 +128,19 @@ virBufferFree(virBufferPtr buf)
>   * virBufferContentAndFree:
>   * @buf: Buffer
>   *
> - * Return the content from the buffer and free (only) the buffer structure.
> + * Get the content from the buffer and free (only) the buffer structure.
> + *
> + * Returns the buffer content or NULL in case of error.
>   */
>  char *
>  virBufferContentAndFree (virBufferPtr buf)
>  {
> -    char *content = buf->content;
> +    char *content;
> +    
> +    if (buf == NULL)
> +        return(NULL);
> +
> +    content = buf->content;
>  
>      free (buf);
>      return content;

I know we do this sort of thing all over the place, but it's bad 
practice (IMHO).  If someone passes a NULL into this function then it's 
an error, and it's better to segfault early rather than compound or hide 
the error.

Of course I wish we were using a language where you could specify these 
rules statically, and in fact I've been analysing the libvirt code using 
some static analysis tools to try & find these types of bugs 
automatically.  Results later ...

Rich.

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