* `struct wim_resource_spec' pointed to by @rspec. @offset_in_res
* identifies the offset at which this particular stream begins in the
* uncompressed data of the resource; this is normally 0, but in general
- * a WIM resource may contain multiple streams. */
+ * a WIM resource may be "packed" and potentially contain multiple
+ * streams. */
RESOURCE_IN_WIM,
/* The stream is located in the external file named by @file_on_disk.
- * On Windows, @file_on_disk may actually specify a named data stream.
- */
+ * On Windows, @file_on_disk may actually specify a named data stream
+ * (file path, then colon, then name of the stream). */
RESOURCE_IN_FILE_ON_DISK,
/* The stream is directly attached in the in-memory buffer pointed to by
};
-/*
- * An entry in the lookup table in the WIM file.
- *
- * It is used to find data streams for files in the WIM.
+/* Specification for a stream, which may be the contents of a file (unnamed data
+ * stream), a named data stream, reparse point data, or a WIM metadata resource.
*
- * Metadata resources and reparse point data buffers will also have lookup table
- * entries associated with the data.
- *
- * The lookup_table_entry for a given dentry or alternate stream entry in the
- * WIM is found using the SHA1 message digest field.
- */
+ * One instance of this structure is created for each entry in the WIM's lookup
+ * table, hence the name of the struct. Each of these entries contains the SHA1
+ * message digest of a stream and the location of the stream data in the WIM
+ * file (size, location, flags). The in-memory lookup table is a map from SHA1
+ * message digests to stream locations. */
struct wim_lookup_table_entry {
- /* List of lookup table entries in this hash bucket */
+ /* List node for a hash bucket of the lookup table. */
struct hlist_node hash_list;
- /* Uncompressed size of the stream. */
+ /* Uncompressed size of this stream. */
u64 size;
/* Stream flags (WIM_RESHDR_FLAG_*). */
u32 flags : 8;
- /* One of the `enum resource_location' values documented above. */
- u32 resource_location : 5;
+ /* One of the `enum resource_location' values documented above. */
+ u32 resource_location : 4;
/* 1 if this stream has not had a SHA1 message digest calculated for it
- * yet */
+ * yet. */
u32 unhashed : 1;
- /* Temoorary files used for writing; set as documented for
+ /* Temoorary fields used when writing streams; set as documented for
* prepare_stream_list_for_write(). */
u32 unique_size : 1;
u32 will_be_in_output_wim : 1;
/* Set to 1 when a metadata entry has its checksum changed; in such
- * cases the hash is no longer valid to verify the data if the metadata
- * resource is read again. */
+ * cases the hash cannot be used to verify the data if the metadata
+ * resource is read again. (This could be avoided if we used separate
+ * fields for input/output checksum, but most stream entries wouldn't
+ * need this.) */
u32 dont_check_metadata_hash : 1;
union {
};
/* Number of times this lookup table entry is referenced by dentries in
- * the WIM. */
+ * the WIM. When a WIM's lookup table is read, this field is
+ * initialized from a corresponding entry; while it should be correct,
+ * in general it may not be. wim_recalculate_refcnts() recalculates the
+ * reference counts for all streams and is run before doing any
+ * deletions. */
u32 refcnt;
- /* Actual reference count to this stream (only used while verifying an
- * image). */
- u32 real_refcnt;
-
- /* When a WIM file is written, out_refcnt starts at 0 and is incremented
- * whenever the stream pointed to by this lookup table entry needs to be
- * written. The stream only need to be written when out_refcnt is
- * nonzero, since otherwise it is not referenced by any dentries. */
+ /* When a WIM file is written, this is set to the number of references
+ * (by dentries) to this stream in the output WIM file.
+ *
+ * During extraction, this is set to the number of times the stream must
+ * be extracted.
+ *
+ * During image export, this is set to the number of references of this
+ * stream that originated from the source WIM. */
u32 out_refcnt;
#ifdef WITH_FUSE
- /* Number of times this stream has been opened (used only during
- * mounting) */
+ /* Number of times this stream has been opened; used only during
+ * mounting. */
u16 num_opened_fds;
#endif
- /* Pointers to somewhere where the stream is actually located. See the
- * comments for the @resource_location field above. */
+ /* Specification of where this stream is actually located. Which member
+ * is valid is determined by the @resource_location field. */
union {
struct {
struct wim_resource_spec *rspec;
};
/* Links together streams that share the same underlying WIM resource.
- * The head is wim_resource_spec.stream_list. */
+ * The head is the `stream_list' member of `struct wim_resource_spec'.
+ */
struct list_head rspec_node;
- /* This field is used for the special hardlink or symlink image
- * extraction mode. In these mode, all identical files are linked
- * together, and @extracted_file will be set to the filename of the
- * first extracted file containing this stream. */
+ /* This field is used during the hardlink and symlink image extraction
+ * modes. In these modes, all identical files are linked together, and
+ * @extracted_file will be set to the filename of the first extracted
+ * file containing this stream. */
tchar *extracted_file;
/* Temporary fields */
union {
- /* Used temporarily during WIM file writing */
+ /* Fields used temporarily during WIM file writing. */
struct {
union {
+ /* List node used for stream size table. */
struct hlist_node hash_list_2;
+
+ /* Metadata for the underlying packed resource
+ * in the WIM being written (only valid if
+ * WIM_RESHDR_FLAG_PACKED_STREAMS set in
+ * out_reshdr.flags). */
struct {
u64 out_res_offset_in_wim;
u64 out_res_size_in_wim;
- u64 out_res_uncompressed_size;
};
};
+
/* Links streams being written to the WIM. */
struct list_head write_streams_list;
+ /* Metadata for this stream in the WIM being written.
+ */
struct wim_reshdr out_reshdr;
};
/* Used temporarily during extraction */
union {
- /* out_refcnt tracks number of slots filled */
- struct wim_dentry *inline_lte_dentries[8];
+ /* Dentries to extract that reference this stream.
+ * out_refcnt tracks the number of slots filled. */
+ struct wim_dentry *inline_lte_dentries[7];
struct {
struct wim_dentry **lte_dentries;
- unsigned long alloc_lte_dentries;
+ size_t alloc_lte_dentries;
};
};
+
+ /* Actual reference count to this stream (only used while
+ * verifying an image). */
+ u32 real_refcnt;
};
- /* Temporary list fields */
+ /* Temporary list fields. */
union {
/* Links streams for writing lookup table. */
struct list_head lookup_table_list;
extern void
lookup_table_insert(struct wim_lookup_table *table, struct wim_lookup_table_entry *lte);
-/* Unlinks a lookup table entry from the table; does not free it. */
+/* Unlinks a lookup table entry from the table; does not free it. */
static inline void
lookup_table_unlink(struct wim_lookup_table *table, struct wim_lookup_table_entry *lte)
{
lte_unbind_wim_resource_spec(struct wim_lookup_table_entry *lte)
{
list_del(<e->rspec_node);
- lte->rspec = NULL;
lte->resource_location = RESOURCE_NONEXISTENT;
}
git://wimlib.net / wimlib / blobdiff