On 10/17/2012 06:30 PM, Eric Blake wrote:
> In order to temporarily label files read/write during a commit
> operation, we need to crawl the backing chain and find the absolute
> file name that needs labeling in the first place, as well as the
> name of the file that owns the backing file.
>
> * src/util/storage_file.c (virStorageFileChainLookup): New
> function.
> * src/util/storage_file.h: Declare it.
> * src/libvirt_private.syms (storage_file.h): Export it.
> ---
>
> v3: fix -Wshadow failure, improve comments
>
> src/libvirt_private.syms | 1 +
> src/util/storage_file.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++
> src/util/storage_file.h | 7 ++++++
> 3 files changed, 72 insertions(+)
>
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 6155738..ccee23d 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -1130,6 +1130,7 @@ virStorageGenerateQcowPassphrase;
>
>
> # storage_file.h
> +virStorageFileChainLookup;
> virStorageFileFormatTypeFromString;
> virStorageFileFormatTypeToString;
> virStorageFileFreeMetadata;
> diff --git a/src/util/storage_file.c b/src/util/storage_file.c
> index 2ff444c..882df6e 100644
> --- a/src/util/storage_file.c
> +++ b/src/util/storage_file.c
> @@ -1262,3 +1262,67 @@ const char *virStorageFileGetSCSIKey(const char *path)
> return NULL;
> }
> #endif
> +
> +/* Given a CHAIN that starts at the named file START, return a string
> + * pointing to either START or within CHAIN that gives the preferred
> + * name for the backing file NAME within that chain. Pass NULL for
> + * NAME to find the base of the chain. If META is not NULL, set *META
> + * to the point in the chain that describes NAME (or to NULL if the
> + * backing element is not a file). If PARENT is not NULL, set *PARENT
> + * to the preferred name of the parent (or to NULL if NAME matches
> + * START). Since the results point within CHAIN, they must not be
> + * independently freed. */
> +const char *
> +virStorageFileChainLookup(virStorageFileMetadataPtr chain, const char *start,
> + const char *name, virStorageFileMetadataPtr *meta,
> + const char **parent)
> +{
> + virStorageFileMetadataPtr owner;
> + const char *tmp;
> +
> + if (!parent)
> + parent = &tmp;
> +
> + *parent = NULL;
> + if (name ? STREQ(start, name) || virFileLinkPointsTo(start, name) :
> + !chain->backingStore) {
> + if (meta)
> + *meta = chain;
> + return start;
> + }
> +
> + owner = chain;
> + *parent = start;
> + while (owner) {
> + if (!owner->backingStore)
> + goto error;
> + if (!name) {
> + if (!owner->backingMeta ||
> + !owner->backingMeta->backingStore)
> + break;
> + } else if (STREQ_NULLABLE(name, owner->backingStoreRaw) ||
> + STREQ(name, owner->backingStore)) {
> + break;
> + } else if (owner->backingStoreIsFile) {
> + char *absName = absolutePathFromBaseFile(*parent, name);
> + if (absName && STREQ(absName, owner->backingStore)) {
> + VIR_FREE(absName);
> + break;
> + }
> + VIR_FREE(absName);
> + }
> + *parent = owner->backingStore;
> + owner = owner->backingMeta;
> + }
> + if (!owner)
> + goto error;
> + if (meta)
> + *meta = owner->backingMeta;
> + return owner->backingStore;
> +
> +error:
> + *parent = NULL;
> + if (meta)
> + *meta = NULL;
> + return NULL;
> +}
> diff --git a/src/util/storage_file.h b/src/util/storage_file.h
> index 685fcb8..9b00dba 100644
> --- a/src/util/storage_file.h
> +++ b/src/util/storage_file.h
> @@ -78,6 +78,13 @@ virStorageFileMetadataPtr virStorageFileGetMetadataFromFD(const char *path,
> int fd,
> int format);
>
> +const char *virStorageFileChainLookup(virStorageFileMetadataPtr chain,
> + const char *start,
> + const char *name,
> + virStorageFileMetadataPtr *meta,
> + const char **parent)
> + ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
> +
> void virStorageFileFreeMetadata(virStorageFileMetadataPtr meta);
>
> int virStorageFileResize(const char *path, unsigned long long capacity);
Previous ACK stands.
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