Re: [libvirt] [PATCHv2 08/33] storage: Add storage file API to read file headers

Add storage driver based functions to access headers of storage files for metadata extraction. Along with this patch a local filesystem and gluster via libgfapi implementation is provided. The gluster implementation is based on code of the saferead_lim function. --- src/storage/storage_backend.h | 7 ++++ src/storage/storage_backend_fs.c | 30 ++++++++++++++++ src/storage/storage_backend_gluster.c | 66 +++++++++++++++++++++++++++++++++++ src/storage/storage_driver.c | 40 +++++++++++++++++++++ src/storage/storage_driver.h | 3 ++ 5 files changed, 146 insertions(+)

+++ b/src/storage/storage_backend_gluster.c @@ -638,6 +638,71 @@ virStorageFileBackendGlusterStat(virStorageSourcePtr src, } +static ssize_t +virStorageFileBackendGlusterReadHeader(virStorageSourcePtr src, + ssize_t max_len, + char **buf) +{ + virStorageFileBackendGlusterPrivPtr priv = src->drv->priv; + glfs_fd_t *fd = NULL; + size_t alloc = 0; + size_t size = 0; + int save_errno; + ssize_t ret = -1; + + *buf = NULL; + + if (!(fd = glfs_open(priv->vol, src->path, O_RDONLY))) { + virReportSystemError(errno, _("Failed to open file '%s'"), + src->path); + goto cleanup; + } + + /* code below is shamelesly stolen from saferead_lim */

+ if (!src->drv->backend->storageFileReadHeader) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("storage file header reading is not supported for " + "storage type %s (protocol: %s)'"), + virStorageTypeToString(src->type), + virStorageNetProtocolTypeToString(src->protocol));

+ return -1;