[libvirt PATCH v2 12/31] storage_source: introduce virStorageSourceChainLookupBySource

[Peter Krempa]

On Thu, Jan 05, 2023 at 12:46:48 +0100, Pavel Hrdina wrote:
> Looks up disk storage source within storage source chain using storage
> source object instead of path to make it work with all disk types.
> 
> Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
> ---
>  src/libvirt_private.syms          |  1 +
>  src/storage_file/storage_source.c | 39 +++++++++++++++++++++++++++++++
>  src/storage_file/storage_source.h |  6 +++++
>  3 files changed, 46 insertions(+)

[...]

> diff --git a/src/storage_file/storage_source.c b/src/storage_file/storage_source.c
> index ab0cdf2b12..a15d766bec 100644
> --- a/src/storage_file/storage_source.c
> +++ b/src/storage_file/storage_source.c
> @@ -322,6 +322,45 @@ virStorageSourceChainLookup(virStorageSource *chain,
>  }
>  
>  
> +/**
> + * virStorageSourceChainLookupBySource:
> + * @chain: chain top to look in
> + * @base: stourage source to look for in @chain

s/stourage/storage/

> + * @parent: Filled with parent virStorageSource of the returned value if non-NULL.
> + *
> + * Looks up a storage source definition corresponding to @base in @chain.
> + *
> + * Returns virStorageSource withing chain or NULL if not found.
> + */
> +virStorageSource *
> +virStorageSourceChainLookupBySource(virStorageSource *chain,
> +                                    virStorageSource *base,
> +                                    virStorageSource **parent)
> +{
> +    virStorageSource *prev = NULL;
> +
> +    if (parent)
> +        *parent = NULL;
> +
> +    while (virStorageSourceIsBacking(chain)) {
> +        if (virStorageSourceIsSameLocation(chain, base))
> +            break;
> +
> +        prev = chain;
> +        chain = chain->backingStore;
> +    }
> +
> +    if (!virStorageSourceIsBacking(chain)) {
> +        virReportError(VIR_ERR_INVALID_ARG, "%s",
> +                       _("could not find base disk source in disk source chain"));
> +        return NULL;
> +    }
> +
> +    *parent = prev;

The comment specifies that passing a pointer for 'parent' is optional
but here you hard-dereference it always. Add the same condition as at
the beginning.

Reviewed-by: Peter Krempa <pkrempa at redhat.com>