#include "wimlib/types.h"
#include "wimlib/wim.h"
-/* Metadata for a WIM image */
+/*
+ * This structure holds the directory tree that comprises a WIM image, along
+ * with other information maintained at the image level. It is populated either
+ * by reading and parsing a metadata resource or by scanning new files.
+ *
+ * An image that hasn't been modified from its on-disk copy is considered
+ * "clean" and is loaded from its metadata resource on demand by
+ * select_wim_image(). Such an image may be unloaded later to save memory when
+ * a different image is selected. An image that has been modified or has been
+ * created from scratch, on the other hand, is considered "dirty" and is never
+ * automatically unloaded.
+ *
+ * To implement exports, it's allowed that multiple WIMStructs reference the
+ * same wim_image_metadata.
+ */
struct wim_image_metadata {
- /* Number of WIMStruct's that are sharing this image metadata (from
- * calls to wimlib_export_image().) */
- unsigned long refcnt;
+ /* Number of WIMStructs that reference this image. This will always be
+ * >= 1. It may be > 1 if this image has been exported. */
+ u32 refcnt;
- /* Pointer to the root dentry of the image. */
+ /* Number of WIMStructs that have this image selected as their
+ * current_image. This will always be <= 'refcnt' and may be 0. */
+ u32 selected_refcnt;
+
+ /* Pointer to the root dentry of this image, or NULL if this image is
+ * completely empty or is not currently loaded. */
struct wim_dentry *root_dentry;
- /* Pointer to the security data of the image. */
+ /* Pointer to the security data of this image, or NULL if this image is
+ * not currently loaded. */
struct wim_security_data *security_data;
/* Pointer to the blob descriptor for this image's metadata resource.
* with blob_location==BLOB_NONEXISTENT. */
struct blob_descriptor *metadata_blob;
- /* Linked list of 'struct wim_inode's for this image. */
+ /* Linked list of 'struct wim_inode's for this image, or an empty list
+ * if this image is completely empty or is not currently loaded. */
struct hlist_head inode_list;
/* Linked list of 'struct blob_descriptor's for blobs that are
imd->stats_outdated = true;
}
+/* Return true iff the specified image is currently loaded into memory. */
+static inline bool
+is_image_loaded(const struct wim_image_metadata *imd)
+{
+ /* Check security_data rather than root_dentry, since root_dentry will
+ * be NULL for a completely empty image whereas security_data will still
+ * be non-NULL in that case. */
+ return imd->security_data != NULL;
+}
+
+/* Return true iff it is okay to unload the specified image. The image can be
+ * unloaded if no WIMStructs have it selected and it is not dirty. */
+static inline bool
+can_unload_image(const struct wim_image_metadata *imd)
+{
+ return imd->selected_refcnt == 0 && !is_image_dirty(imd);
+}
+
/* Iterate over each inode in a WIM image */
#define image_for_each_inode(inode, imd) \
hlist_for_each_entry(inode, &(imd)->inode_list, i_hlist_node)
list_for_each_entry_safe(blob, tmp, &(imd)->unhashed_blobs, unhashed_list)
extern void
-put_image_metadata(struct wim_image_metadata *imd, struct blob_table *table);
+put_image_metadata(struct wim_image_metadata *imd);
extern int
append_image_metadata(WIMStruct *wim, struct wim_image_metadata *imd);
extern struct wim_image_metadata *
-new_image_metadata(void) _malloc_attribute;
+new_empty_image_metadata(void);
+
+extern struct wim_image_metadata *
+new_unloaded_image_metadata(struct blob_descriptor *metadata_blob);
#endif /* _WIMLIB_METADATA_H */