[wimlib] / include / wimlib / lookup_table.h

#ifndef _WIMLIB_LOOKUP_TABLE_H
#define _WIMLIB_LOOKUP_TABLE_H

#include "wimlib/list.h"
#include "wimlib/resource.h"
#include "wimlib/sha1.h"
#include "wimlib/types.h"

/* An enumerated type that identifies where the stream corresponding to this
 * lookup table entry is actually located.
 *
 * If we open a WIM and read its lookup table, the location is set to
 * RESOURCE_IN_WIM since all the streams will initially be located in the WIM.
 * However, to handle situations such as image capture and image mount, we allow
 * the actual location of the stream to be somewhere else, such as an external
 * file.  */
enum resource_location {
        /* The lookup table entry does not yet correspond to a stream; this is a
         * temporary state only.  */
        RESOURCE_NONEXISTENT = 0,

        /* The stream is located in a resource in a WIM file identified by the
         * `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 a WIM
         * resource can be "solid" and contain multiple streams.  */
        RESOURCE_IN_WIM,

        /* The stream is located in the external file named by @file_on_disk.
         */
        RESOURCE_IN_FILE_ON_DISK,

        /* The stream is directly attached in the in-memory buffer pointed to by
         * @attached_buffer.  */
        RESOURCE_IN_ATTACHED_BUFFER,

#ifdef WITH_FUSE
        /* The stream is located in the external file named by
         * @staging_file_name, located in the staging directory for a read-write
         * mount.  */
        RESOURCE_IN_STAGING_FILE,
#endif

#ifdef WITH_NTFS_3G
        /* The stream is located in an NTFS volume.  It is identified by volume,
         * filename, data stream name, and by whether it is a reparse point or
         * not.  @ntfs_loc points to a structure containing this information.
         * */
        RESOURCE_IN_NTFS_VOLUME,
#endif

#ifdef __WIN32__
        /* Windows only: the stream is located in the external file named by
         * @file_on_disk, which is in the Windows NT namespace and may specify a
         * named data stream.  */
        RESOURCE_IN_WINNT_FILE_ON_DISK,

        /* Windows only: the stream is located in the external file named by
         * @file_on_disk, but the file is encrypted and must be read using the
         * appropriate Windows API.  */
        RESOURCE_WIN32_ENCRYPTED,
#endif
};

struct stream_owner {
        struct wim_inode *inode;
        const utf16lechar *stream_name;
};

/* 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.
 *
 * 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 node for a hash bucket of the lookup table.  */
        struct hlist_node hash_list;

        /* 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 : 4;

        /* 1 if this stream has not had a SHA1 message digest calculated for it
         * yet.  */
        u32 unhashed : 1;

        /* 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 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;

        u32 may_send_done_with_file : 1;

        /* Only used by wimlib_export_image() */
        u32 was_exported : 1;

        union {
                /* (On-disk field) SHA1 message digest of the stream referenced
                 * by this lookup table entry.  */
                u8  hash[SHA1_HASH_SIZE];

                /* First 4 or 8 bytes of the SHA1 message digest, used for
                 * inserting the entry into the hash table.  Since the SHA1
                 * message digest can be considered random, we don't really need
                 * the full 20 byte hash just to insert the entry in a hash
                 * table.  */
                size_t hash_short;

                /* Unhashed entries only (unhashed == 1): these variables make
                 * it possible to find the pointer to this 'struct
                 * wim_lookup_table_entry' contained in either 'struct
                 * wim_ads_entry' or 'struct wim_inode'.  There can be at most 1
                 * such pointer, as we can only join duplicate streams after
                 * they have been hashed.  */
                struct {
                        struct wim_inode *back_inode;
                        u32 back_stream_id;
                };
        };

        /* Number of times this lookup table entry is referenced by dentries in
         * the WIM.  When a WIM's lookup table is read, this field is
         * initialized from a corresponding entry.
         *
         * However, see lte_decrement_refcnt() for information about the
         * limitations of this field.  */
        u32 refcnt;

        /* 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 the number of slots in stream_owners (or
         * inline_stream_owners) that have been filled.
         *
         * During image export, this is set to the number of references of this
         * stream that originated from the source WIM.
         *
         * When mounting a WIM image read-write, this is set to the number of
         * extra references to this stream preemptively taken to allow later
         * saving the modified image as a new image and leaving the original
         * image alone.  */
        u32 out_refcnt;

#ifdef WITH_FUSE
        /* Number of open file descriptors to this stream during a FUSE mount of
         * the containing image.  */
        u16 num_opened_fds;
#endif

        /* 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;
                        u64 offset_in_res;
                };
                struct {
                        tchar *file_on_disk;
                        struct wim_inode *file_inode;
                };
                void *attached_buffer;
        #ifdef WITH_FUSE
                struct {
                        char *staging_file_name;
                        int staging_dir_fd;
                };
        #endif
        #ifdef WITH_NTFS_3G
                struct ntfs_location *ntfs_loc;
        #endif
        };

        /* Links together streams that share the same underlying WIM resource.
         * The head is the `stream_list' member of `struct wim_resource_spec'.
         */
        struct list_head rspec_node;

        /* Temporary fields  */
        union {
                /* 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 solid resource in
                                 * the WIM being written (only valid if
                                 * WIM_RESHDR_FLAG_SOLID 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.  This is an array of
                 * pointers to the inodes being extracted that use this stream.
                 */
                union {
                        /* Inodes to extract that reference this stream.
                         * out_refcnt tracks the number of slots filled.  */
                        struct stream_owner inline_stream_owners[3];
                        struct {
                                struct stream_owner *stream_owners;
                                u32 alloc_stream_owners;
                        };
                };
        };

        /* Temporary list fields.  */
        union {
                /* Links streams for writing lookup table.  */
                struct list_head lookup_table_list;

                /* Links streams being extracted.  */
                struct list_head extraction_list;

                /* Links streams being exported.  */
                struct list_head export_stream_list;

                /* Links original list of streams in the read-write mounted image.  */
                struct list_head orig_stream_list;
        };

        /* Links streams that are still unhashed after being been added to a
         * WIM.  */
        struct list_head unhashed_list;
};

/* Functions to allocate and free lookup tables  */

extern struct wim_lookup_table *
new_lookup_table(size_t capacity) _malloc_attribute;

extern void
free_lookup_table(struct wim_lookup_table *table);

/* Functions to read or write the lookup table from/to a WIM file  */

extern int
read_wim_lookup_table(WIMStruct *wim);

extern int
write_wim_lookup_table_from_stream_list(struct list_head *stream_list,
                                        struct filedes *out_fd,
                                        u16 part_number,
                                        struct wim_reshdr *out_reshdr,
                                        int write_resource_flags);

/* Functions to create, clone, print, and free lookup table entries  */

extern struct wim_lookup_table_entry *
new_lookup_table_entry(void) _malloc_attribute;

extern struct wim_lookup_table_entry *
clone_lookup_table_entry(const struct wim_lookup_table_entry *lte)
                        _malloc_attribute;

extern void
lte_decrement_refcnt(struct wim_lookup_table_entry *lte,
                     struct wim_lookup_table *table);
#ifdef WITH_FUSE
extern void
lte_decrement_num_opened_fds(struct wim_lookup_table_entry *lte);
#endif

extern void
free_lookup_table_entry(struct wim_lookup_table_entry *lte);

/* Functions to insert and delete entries from a lookup table  */

extern void
lookup_table_insert(struct wim_lookup_table *table,
                struct wim_lookup_table_entry *lte);

extern void
lookup_table_unlink(struct wim_lookup_table *table,
                    struct wim_lookup_table_entry *lte);

/* Function to lookup a stream by SHA1 message digest  */
extern struct wim_lookup_table_entry *
lookup_stream(const struct wim_lookup_table *table, const u8 hash[]);

/* Functions to iterate through the entries of a lookup table  */

extern int
for_lookup_table_entry(struct wim_lookup_table *table,
                       int (*visitor)(struct wim_lookup_table_entry *, void *),
                       void *arg);

extern int
for_lookup_table_entry_pos_sorted(struct wim_lookup_table *table,
                                  int (*visitor)(struct wim_lookup_table_entry *,
                                                 void *),
                                  void *arg);



/* Function to get a resource entry in stable format  */

struct wimlib_resource_entry;

extern void
lte_to_wimlib_resource_entry(const struct wim_lookup_table_entry *lte,
                             struct wimlib_resource_entry *wentry);

/* Functions to sort a list of lookup table entries  */
extern int
sort_stream_list(struct list_head *stream_list,
                 size_t list_head_offset,
                 int (*compar)(const void *, const void*));

extern int
sort_stream_list_by_sequential_order(struct list_head *stream_list,
                                     size_t list_head_offset);

/* Utility functions  */

extern int
lte_zero_out_refcnt(struct wim_lookup_table_entry *lte, void *ignore);

static inline bool
lte_is_partial(const struct wim_lookup_table_entry * lte)
{
        return lte->resource_location == RESOURCE_IN_WIM &&
               lte->size != lte->rspec->uncompressed_size;
}

static inline const struct stream_owner *
stream_owners(struct wim_lookup_table_entry *stream)
{
        if (stream->out_refcnt <= ARRAY_LEN(stream->inline_stream_owners))
                return stream->inline_stream_owners;
        else
                return stream->stream_owners;
}

static inline void
lte_bind_wim_resource_spec(struct wim_lookup_table_entry *lte,
                           struct wim_resource_spec *rspec)
{
        lte->resource_location = RESOURCE_IN_WIM;
        lte->rspec = rspec;
        list_add_tail(&lte->rspec_node, &rspec->stream_list);
}

static inline void
lte_unbind_wim_resource_spec(struct wim_lookup_table_entry *lte)
{
        list_del(&lte->rspec_node);
        lte->resource_location = RESOURCE_NONEXISTENT;
}

extern void
lte_put_resource(struct wim_lookup_table_entry *lte);

extern struct wim_lookup_table_entry *
new_stream_from_data_buffer(const void *buffer, size_t size,
                            struct wim_lookup_table *lookup_table);

static inline void
add_unhashed_stream(struct wim_lookup_table_entry *lte,
                    struct wim_inode *back_inode,
                    u32 back_stream_id,
                    struct list_head *unhashed_streams)
{
        lte->unhashed = 1;
        lte->back_inode = back_inode;
        lte->back_stream_id = back_stream_id;
        list_add_tail(&lte->unhashed_list, unhashed_streams);
}

extern int
hash_unhashed_stream(struct wim_lookup_table_entry *lte,
                     struct wim_lookup_table *lookup_table,
                     struct wim_lookup_table_entry **lte_ret);

extern struct wim_lookup_table_entry **
retrieve_lte_pointer(struct wim_lookup_table_entry *lte);

#endif /* _WIMLIB_LOOKUP_TABLE_H */