[Qemu-devel] Re: [PATCH] add support for protocol driver create_options

[Kevin Wolf <kwolf@redhat.com>]

Am 24.05.2010 08:34, schrieb MORITA Kazutaka:
> At Fri, 21 May 2010 18:57:36 +0200,
> Kevin Wolf wrote:
>>
>> Am 20.05.2010 07:36, schrieb MORITA Kazutaka:
>>> +
>>> +/*
>>> + * Append an option list (list) to an option list (dest).
>>> + *
>>> + * If dest is NULL, a new copy of list is created.
>>> + *
>>> + * Returns a pointer to the first element of dest (or the newly allocated copy)
>>> + */
>>> +QEMUOptionParameter *append_option_parameters(QEMUOptionParameter *dest,
>>> +    QEMUOptionParameter *list)
>>> +{
>>> +    size_t num_options, num_dest_options;
>>> +
>>> +    num_options = count_option_parameters(dest);
>>> +    num_dest_options = num_options;
>>> +
>>> +    num_options += count_option_parameters(list);
>>> +
>>> +    dest = qemu_realloc(dest, (num_options + 1) * sizeof(QEMUOptionParameter));
>>> +
>>> +    while (list && list->name) {
>>> +        if (get_option_parameter(dest, list->name) == NULL) {
>>> +            dest[num_dest_options++] = *list;
>>
>> You need to add a dest[num_dest_options].name = NULL; here. Otherwise
>> the next loop iteration works on uninitialized memory and possibly an
>> unterminated list. I got a segfault for that reason.
>>
> 
> I forgot to add it, sorry.
> Fixed version is below.
> 
> Thanks,
> 
> Kazutaka
> 
> ==
> This patch enables protocol drivers to use their create options which
> are not supported by the format.  For example, protcol drivers can use
> a backing_file option with raw format.
> 
> Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>

$ ./qemu-img create -f qcow2 -o cluster_size=4k /tmp/test.qcow2 4G
Unknown option 'cluster_size'
qemu-img: Invalid options for file format 'qcow2'.

I think you added another num_dest_options++ which shouldn't be there.

Kevin