* dentry_tree_fix_inodes() in hardlink.c).
*/
struct wim_dentry {
- /* The inode for this dentry */
+ /* Pointer to the inode for this dentry. This will contain some
+ * information that was factored out of the on-disk WIM dentry as common
+ * to all dentries in a hard link group. */
struct wim_inode *d_inode;
/* Node for the parent's red-black tree of child dentries, sorted by
* including the terminating null character. */
u32 full_path_nbytes;
- /* Does this dentry need to be extracted? */
+ /* For extraction operations, a subtree of dentries will have this flag
+ * set so we can keep track of which dentries still need to be
+ * extracted. Otherwise this will always be 0. */
u8 needs_extraction : 1;
+ /* For extraction operations, this flag will be set when a dentry in the
+ * tree being extracted is not being extracted for some reason (file
+ * type not supported by target filesystem or contains invalid
+ * characters). Otherwise this will always be 0. */
u8 not_extracted : 1;
- /* Only used during NTFS capture */
+ /* When capturing from a NTFS volume using NTFS-3g, this flag is set on
+ * dentries that were created from a filename in the WIN32 or WIN32+DOS
+ * namespaces rather than the POSIX namespace. Otherwise this will
+ * always be 0. */
u8 is_win32_name : 1;
- /* Set to 1 if an inode has multiple DOS names. */
+ /* When verifying the dentry tree after reading it into memory, this
+ * flag will be set on all dentries in a hard link group that have a
+ * nonempty DOS name except one. This is because it is supposed to be
+ * illegal (on NTFS, at least) for a single inode to have multiple DOS
+ * names. */
u8 dos_name_invalid : 1;
- /* Temporary list */
+ /* Temporary list field used to make lists of dentries in a few places.
+ * */
struct list_head tmp_list;
- /* List of dentries in the inode (hard link set) */
+ /* Linked list node that places this dentry in the list of aliases for
+ * its inode (d_inode) */
struct list_head d_alias;
/* The parent of this directory entry. */
struct wim_dentry *parent;
- /*
- * Size of directory entry on disk, in bytes. Typical size is around
- * 104 to 120 bytes.
- *
- * It is possible for the length field to be 0. This situation, which
- * is undocumented, indicates the end of a list of sibling nodes in a
- * directory. It also means the real length is 8, because the dentry
- * included only the length field, but that takes up 8 bytes.
- *
- * The length here includes the base directory entry on disk as well as
- * the long and short filenames. It does NOT include any alternate
- * stream entries that may follow the directory entry, even though the
- * size of those needs to be considered. The length SHOULD be 8-byte
- * aligned, although we don't require it to be. We do require the
- * length to be large enough to hold the file name(s) of the dentry;
- * additionally, a warning is issued if this field is larger than the
- * aligned size.
- */
+ /* 'length' and 'subdir_offset' are only used while reading and writing
+ * this dentry; see the corresponding field in
+ * `struct wim_dentry_on_disk' for explanation. */
u64 length;
-
- /* The offset, from the start of the uncompressed WIM metadata resource
- * for this image, of this dentry's child dentries. 0 if the directory
- * entry has no children, which is the case for regular files or reparse
- * points. */
u64 subdir_offset;
+ /* These correspond to the two unused fields in the on-disk WIM dentry;
+ * we read them into memory so we can write them unchanged. These
+ * fields are set to 0 on new dentries. */
u64 d_unused_1;
u64 d_unused_2;
- /* Pointer to the UTF-16LE short filename (malloc()ed buffer) */
+ /* Pointer to the UTF-16LE short filename (malloc()ed buffer), or NULL
+ * if this dentry has no short name. */
utf16lechar *short_name;
- /* Pointer to the UTF-16LE filename (malloc()ed buffer). */
+ /* Pointer to the UTF-16LE filename (malloc()ed buffer), or NULL if this
+ * dentry has no filename. */
utf16lechar *file_name;
- /* Full path of this dentry in the WIM */
+ /* Full path to this dentry in the WIM, in platform-dependent "tchars"
+ * that can be printed without convension. By default this field will
+ * be NULL and will only be calculated on-demand by the
+ * calculate_dentry_full_path() or dentry_full_path() functions. */
tchar *_full_path;
- /* Actual name to extract this dentry as. */
+ /* (Extraction only) Actual name to extract this dentry as, along with
+ * its length in tchars excluding the NULL terminator. This usually
+ * will be the same as file_name, with the character encoding converted
+ * if needed. But if file_name contains characters not accepted on the
+ * current platform, then this may be set slightly differently from
+ * file_name. This will be either NULL or a malloc()ed buffer that may
+ * alias file_name. */
tchar *extraction_name;
size_t extraction_name_nchars;
- /* List head for building a list of dentries that contain a certain
- * stream. */
+ /* (Extraction only) List head for building a list of dentries that
+ * contain a certain stream. */
struct list_head extraction_stream_list;
};
#define WIM_ADS_ENTRY_DISK_SIZE 38
-/* WIM directory entry (on-disk format) */
+/* On-disk format of a WIM dentry (directory entry), located in the metadata
+ * resource for a WIM image. */
struct wim_dentry_on_disk {
+
+ /* Length of this directory entry in bytes, not including any alternate
+ * data stream entries. Should be a multiple of 8 so that the following
+ * dentry or alternate data stream entry is aligned on an 8-byte
+ * boundary. (If not, wimlib will round it up.)
+ *
+ * It is also possible for this field to be 0. This situation, which is
+ * undocumented, indicates the end of a list of sibling nodes in a
+ * directory. It also means the real length is 8, because the dentry
+ * included only the length field, but that takes up 8 bytes. */
le64 length;
+
+ /* Attributes of the file or directory. This is a bitwise OR of the
+ * FILE_ATTRIBUTE_* constants and should correspond to the value
+ * retrieved by GetFileAttributes() on Windows. */
le32 attributes;
+
+ /* A value that specifies the security descriptor for this file or
+ * directory. If -1, the file or directory has no security descriptor.
+ * Otherwise, it is a 0-based index into the WIM image's table of
+ * security descriptors (see: `struct wim_security_data') */
sle32 security_id;
+
+ /* Offset from the start of the uncompressed metadata resource of this
+ * directory's child directory entries, or 0 if this directory entry
+ * does not correspond to a directory or otherwise does not have any
+ * children. */
le64 subdir_offset;
+
+ /* Reserved fields */
le64 unused_1;
le64 unused_2;
+
+ /* The following three time fields should correspond to those gotten by
+ * calling GetFileTime() on Windows. */
+
+ /* Creation time, in 100-nanosecond intervals since January 1, 1601. */
le64 creation_time;
+
+ /* Last access time, in 100-nanosecond intervals since January 1, 1601. */
le64 last_access_time;
+
+ /* Last write time, in 100-nanosecond intervals since January 1, 1601. */
le64 last_write_time;
+
+ /* Vaguely, the SHA-1 message digest ("hash") of the file's contents.
+ * More specifically, this is for the "unnamed data stream" rather than
+ * any "alternate data streams". This hash value is used to look up the
+ * corresponding entry in the WIM's stream lookup table to actually find
+ * the file contents within the WIM.
+ *
+ * If the file has no unnamed data stream (e.g. is a directory), then
+ * this field will be all zeroes. If the unnamed data stream is empty
+ * (i.e. an "empty file"), then this field is also expected to be all
+ * zeroes. (It will be if wimlib created the WIM image, at least;
+ * otherwise it can't be ruled out that the SHA-1 message digest of 0
+ * bytes of data is given explicitly.)
+ *
+ * If the file has reparse data, then this field will instead specify
+ * the SHA-1 message digest of the reparse data. If it is somehow
+ * possible for a file to have both an unnamed data stream and reparse
+ * data, then this is not handled by wimlib.
+ *
+ * As a further special case, if this field is all zeroes but there is
+ * an alternate data stream entry with no name and a nonzero SHA-1
+ * message digest field, then that hash must be used instead of this
+ * one. (wimlib does not use this quirk on WIM images it creates.)
+ */
u8 unnamed_stream_hash[SHA1_HASH_SIZE];
+
+ /* The format of the following data is not yet completely known and they
+ * do not correspond to Microsoft's documentation.
+ *
+ * If this directory entry is for a reparse point (has
+ * FILE_ATTRIBUTE_REPARSE_POINT set in the attributes field), then the
+ * version of the following fields containing the reparse tag is valid.
+ * Furthermore, the field notated as not_rpfixed, as far as I can tell,
+ * is supposed to be set to 1 if reparse point fixups (a.k.a. fixing the
+ * targets of absolute symbolic links) were done, and otherwise 0.
+ *
+ * If this directory entry is not for a reparse point, then the version
+ * of the following fields containing the hard_link_group_id is valid.
+ * All MS says about this field is that "If this file is part of a hard
+ * link set, all the directory entries in the set will share the same
+ * value in this field.". However, more specifically I have observed
+ * the following:
+ * - If the file is part of a hard link set of size 1, then the
+ * hard_link_group_id should be set to either 0, which is treated
+ * specially as indicating "not hardlinked", or any unique value.
+ * - The specific nonzero values used to identity hard link sets do
+ * not matter, as long as they are unique.
+ * - However, due to bugs in Microsoft's software, it is actually NOT
+ * guaranteed that directory entries that share the same hard link
+ * group ID are actually hard linked to each either. We have to
+ * handle this by using special code to use distinguishing features
+ * (possible because some information about the underlying inode is
+ * repeated in each dentry) to split up these fake hard link groups
+ * into what they actually are supposed to be.
+ */
union {
struct {
le32 rp_unknown_1;
le64 hard_link_group_id;
} _packed_attribute nonreparse;
};
+
+ /* Number of alternate data stream entries that directly follow this
+ * dentry on-disk. */
le16 num_alternate_data_streams;
+
+ /* Length of this file's UTF-16LE encoded short name (8.3 DOS-compatible
+ * name), if present, in bytes, excluding the null terminator. If this
+ * file has no short name, then this field should be 0. */
le16 short_name_nbytes;
+
+ /* Length of this file's UTF-16LE encoded "long" name, excluding the
+ * null terminator. If this file has no short name, then this field
+ * should be 0. It's expected that only the root dentry has this field
+ * set to 0. */
le16 file_name_nbytes;
- /* Follewed by variable length file name, if file_name_nbytes != 0 */
+ /* Follewed by variable length file name, in UTF16-LE, if
+ * file_name_nbytes != 0. Includes null terminator. */
utf16lechar file_name[];
- /* Followed by variable length short name, if short_name_nbytes != 0 */
+ /* Followed by variable length short name, in UTF16-LE, if
+ * short_name_nbytes != 0. Includes null terminator. */
/*utf16lechar short_name[];*/
} _packed_attribute;
* fixed-length fields */
if (dentry->length < sizeof(struct wim_dentry_on_disk)) {
ERROR("Directory entry has invalid length of %"PRIu64" bytes",
- dentry->length);
+ entry->length);
return WIMLIB_ERR_INVALID_DENTRY;
}
git://wimlib.net / wimlib / commitdiff