[wimlib] / include / wimlib / lookup_table.h

#ifndef _WIMLIB_LOOKUP_TABLE_H
#define _WIMLIB_LOOKUP_TABLE_H

#include "wimlib/assert.h"
#include "wimlib/dentry.h"
#include "wimlib/list.h"
#include "wimlib/sha1.h"
#include "wimlib/types.h"
#include "wimlib/wim.h"

#define LOOKUP_FLAG_ADS_OK              0x00000001
#define LOOKUP_FLAG_DIRECTORY_OK        0x00000002


/* The lookup table of a WIM file maps SHA1 message digests to streams of data.
 * Here, the in-memory structure is implemented as a hash table.
 *
 * Given a SHA1 message digest, the mapped-to stream is specified by an offset
 * in the WIM, an uncompressed and compressed size, and resource flags (see
 * 'struct resource_entry').  But, we associate additional information, such as
 * a reference count, with each stream, so the actual mapping is from SHA1
 * message digests to 'struct wim_lookup_table_entry's, each of which contains
 * an embedded 'struct resource_entry'.
 *
 * Note: Everything will break horribly if there is a SHA1 collision.
 */
struct wim_lookup_table {
        struct hlist_head *array;
        u64 num_entries;
        u64 capacity;
        struct list_head *unhashed_streams;
};

#ifdef WITH_NTFS_3G

struct _ntfs_volume;

struct ntfs_location {
        tchar *path;
        utf16lechar *stream_name;
        u16 stream_name_nchars;
        struct _ntfs_volume *ntfs_vol;
        bool is_reparse_point;
};
#endif

/* 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 deal with problems 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 correspond to a stream (this state
         * should exist only temporarily) */
        RESOURCE_NONEXISTENT = 0,

        /* The stream resource is located in a WIM file.  The WIMStruct for the
         * WIM file will be pointed to by the @wim member.  The compression type
         * of the resource will be cached in @compression_type, and the pipable
         * status of the resource will be cached in @pipable.  */
        RESOURCE_IN_WIM,

        /* The stream resource is located in an external file.  The name of the
         * file will be provided by @file_on_disk member.
         *
         * Note: On Windows @file_on_disk may actually specify a named data
         * stream.  */
        RESOURCE_IN_FILE_ON_DISK,

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

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

#ifdef WITH_NTFS_3G
        /* The stream resource 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 file is on disk in the file named @file_on_disk,
         * but the file is encrypted and must be read using special functions.
         * */
        RESOURCE_WIN32_ENCRYPTED,
#endif

};

/*
 * An entry in the lookup table in the WIM file.
 *
 * It is used to find data streams for files in the WIM.
 *
 * 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.
 */
struct wim_lookup_table_entry {

        /* List of lookup table entries in this hash bucket */
        struct hlist_node hash_list;

        /* Location and size of the stream in the WIM, whether it is compressed
         * or not, and whether it's a metadata resource or not.  This is an
         * on-disk field. */
        struct resource_entry resource_entry;

        /* Specifies which part of the split WIM the resource is located in.
         * This is on on-disk field.
         *
         * In stand-alone WIMs, this must be 1.
         *
         * In split WIMs, every split WIM part has its own lookup table, and in
         * read_lookup_table() it's currently expected that the part number of
         * each lookup table entry in a split WIM part's lookup table is the
         * same as the part number of that split WIM part.  So this makes this
         * field redundant since we store a pointer to the corresponding
         * WIMStruct in the lookup table entry anyway.
         */
        u16 part_number;

        /* One of the `enum resource_location' values documented above. */
        u16 resource_location : 5;

        /* 1 if this stream is a unique size (only set while writing streams). */
        u16 unique_size : 1;

        /* 1 if this stream has not had a SHA1 message digest calculated for it
         * yet */
        u16 unhashed : 1;

        u16 deferred : 1;

        u16 no_progress : 1;

        /* If resource_location == RESOURCE_IN_WIM, this will be a cached value
         * that specifies the compression type of this stream as one of
         * WIMLIB_COMPRESSION_TYPE_*.  Otherwise this will be 0, which is the
         * same as WIMLIB_COMPRESSION_TYPE_NONE.  */
        u16 compression_type : 2;

        /* If resource_location == RESOURCE_IN_WIM, this flag will be set if the
         * WIM is pipable and therefore the stream is in a slightly different
         * format.  See comment above write_pipable_wim().  */
        u16 is_pipable : 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.  */
        u16 dont_check_metadata_hash : 1;

        /* (On-disk field)
         * Number of times this lookup table entry is referenced by dentries.
         * Unfortunately, this field is not always set correctly in Microsoft's
         * WIMs, so we have no choice but to fix it if more references to the
         * lookup table entry are found than stated here.  */
        u32 refcnt;

        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;
                };
        };

        /* 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. */
        u32 out_refcnt;

        /* Pointers to somewhere where the stream is actually located.  See the
         * comments for the @resource_location field above. */
        union {
                WIMStruct *wim;
                tchar *file_on_disk;
                void *attached_buffer;
        #ifdef WITH_FUSE
                tchar *staging_file_name;
        #endif
        #ifdef WITH_NTFS_3G
                struct ntfs_location *ntfs_loc;
        #endif
        };

        /* Actual reference count to this stream (only used while
         * verifying an image). */
        u32 real_refcnt;

        union {
        #ifdef WITH_FUSE
                /* Number of times this stream has been opened (used only during
                 * mounting) */
                u16 num_opened_fds;
        #endif

                /* 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.  */
                tchar *extracted_file;
        };

        /* Temporary fields  */
        union {
                /* Used temporarily during WIM file writing  */
                struct {
                        struct hlist_node hash_list_2;

                        /* Links streams being written to the WIM.  */
                        struct list_head write_streams_list;
                };

                /* Used temporarily during WIM file writing (after above)  */
                struct {
                        struct list_head msg_list;
                        struct list_head being_compressed_list;
                };

                /* When a WIM file is written, @output_resource_entry is filled
                 * in with the resource entry for the output WIM.  This will not
                 * necessarily be the same as the @resource_entry since:
                 * - The stream may have a different offset in the new WIM
                 * - The stream may have a different compressed size in the new
                 *   WIM if the compression type changed
                 */
                struct resource_entry output_resource_entry;


                /* Used temporarily during extraction  */
                union {
                        /* out_refcnt tracks number of slots filled */
                        struct wim_dentry *inline_lte_dentries[4];
                        struct {
                                struct wim_dentry **lte_dentries;
                                unsigned long alloc_lte_dentries;
                        };
                };
        };

        /* Temporary list fields */
        union {
                /* Links streams when 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 streams that are still unhashed after being been added
         * to a WIM.  */
        struct list_head unhashed_list;
};

static inline u64
wim_resource_size(const struct wim_lookup_table_entry *lte)
{
        return lte->resource_entry.original_size;
}

static inline u64
wim_resource_chunks(const struct wim_lookup_table_entry *lte)
{
        return DIV_ROUND_UP(wim_resource_size(lte), WIM_CHUNK_SIZE);
}

static inline u64
wim_resource_compressed_size(const struct wim_lookup_table_entry *lte)
{
        return lte->resource_entry.size;
}

static inline int
wim_resource_compression_type(const struct wim_lookup_table_entry *lte)
{
        BUILD_BUG_ON(WIMLIB_COMPRESSION_TYPE_NONE != 0);
        return lte->compression_type;
}

static inline bool
lte_filename_valid(const struct wim_lookup_table_entry *lte)
{
        return     lte->resource_location == RESOURCE_IN_FILE_ON_DISK
        #ifdef __WIN32__
                || lte->resource_location == RESOURCE_WIN32_ENCRYPTED
        #endif
        #ifdef WITH_FUSE
                || lte->resource_location == RESOURCE_IN_STAGING_FILE
        #endif
                ;
}

extern struct wim_lookup_table *
new_lookup_table(size_t capacity) _malloc_attribute;

extern int
read_wim_lookup_table(WIMStruct *wim);

extern int
write_wim_lookup_table(WIMStruct *wim, int image, int write_flags,
                       struct resource_entry *out_res_entry,
                       struct list_head *stream_list_override);

extern void
free_lookup_table(struct wim_lookup_table *table);

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. */
static inline void
lookup_table_unlink(struct wim_lookup_table *table, struct wim_lookup_table_entry *lte)
{
        wimlib_assert(!lte->unhashed);
        hlist_del(&lte->hash_list);
        wimlib_assert(table->num_entries != 0);
        table->num_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
print_lookup_table_entry(const struct wim_lookup_table_entry *entry,
                         FILE *out);

extern void
free_lookup_table_entry(struct wim_lookup_table_entry *lte);

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

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

extern int
cmp_streams_by_wim_position(const void *p1, const void *p2);

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

extern struct wim_lookup_table_entry *
__lookup_resource(const struct wim_lookup_table *table, const u8 hash[]);

extern int
lookup_resource(WIMStruct *wim, const tchar *path,
                int lookup_flags, struct wim_dentry **dentry_ret,
                struct wim_lookup_table_entry **lte_ret, u16 *stream_idx_ret);

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 int
lte_zero_out_refcnt(struct wim_lookup_table_entry *entry, void *ignore);

extern int
lte_zero_real_refcnt(struct wim_lookup_table_entry *entry, void *ignore);

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

extern void
lte_init_wim(struct wim_lookup_table_entry *lte, WIMStruct *wim);

extern int
inode_resolve_ltes(struct wim_inode *inode, struct wim_lookup_table *table,
                   bool force);

extern void
inode_unresolve_ltes(struct wim_inode *inode);

static inline struct wim_lookup_table_entry *
inode_stream_lte_resolved(const struct wim_inode *inode, unsigned stream_idx)
{
        wimlib_assert(inode->i_resolved);
        wimlib_assert(stream_idx <= inode->i_num_ads);
        if (stream_idx == 0)
                return inode->i_lte;
        else
                return inode->i_ads_entries[stream_idx - 1].lte;
}

static inline struct wim_lookup_table_entry *
inode_stream_lte_unresolved(const struct wim_inode *inode, unsigned stream_idx,
                            const struct wim_lookup_table *table)
{
        wimlib_assert(!inode->i_resolved);
        wimlib_assert(stream_idx <= inode->i_num_ads);
        if (!table)
                return NULL;
        if (stream_idx == 0)
                return __lookup_resource(table, inode->i_hash);
        else
                return __lookup_resource(table,
                                         inode->i_ads_entries[
                                                stream_idx - 1].hash);
}

extern struct wim_lookup_table_entry *
inode_stream_lte(const struct wim_inode *inode, unsigned stream_idx,
                 const struct wim_lookup_table *table);

static inline const u8 *
inode_stream_hash_unresolved(const struct wim_inode *inode, unsigned stream_idx)
{
        wimlib_assert(!inode->i_resolved);
        wimlib_assert(stream_idx <= inode->i_num_ads);
        if (stream_idx == 0)
                return inode->i_hash;
        else
                return inode->i_ads_entries[stream_idx - 1].hash;
}


static inline const u8 *
inode_stream_hash_resolved(const struct wim_inode *inode, unsigned stream_idx)
{
        struct wim_lookup_table_entry *lte;
        lte = inode_stream_lte_resolved(inode, stream_idx);
        if (lte)
                return lte->hash;
        else
                return zero_hash;
}

/*
 * Returns the hash for stream @stream_idx of the inode, where stream_idx = 0
 * means the default un-named file stream, and stream_idx >= 1 corresponds to an
 * alternate data stream.
 *
 * This works for both resolved and un-resolved dentries.
 */
static inline const u8 *
inode_stream_hash(const struct wim_inode *inode, unsigned stream_idx)
{
        if (inode->i_resolved)
                return inode_stream_hash_resolved(inode, stream_idx);
        else
                return inode_stream_hash_unresolved(inode, stream_idx);
}

static inline u16
inode_stream_name_nbytes(const struct wim_inode *inode, unsigned stream_idx)
{
        wimlib_assert(stream_idx <= inode->i_num_ads);
        if (stream_idx == 0)
                return 0;
        else
                return inode->i_ads_entries[stream_idx - 1].stream_name_nbytes;
}

extern struct wim_lookup_table_entry *
inode_unnamed_lte_resolved(const struct wim_inode *inode);

extern struct wim_lookup_table_entry *
inode_unnamed_lte_unresolved(const struct wim_inode *inode,
                             const struct wim_lookup_table *table);

extern struct wim_lookup_table_entry *
inode_unnamed_lte(const struct wim_inode *inode, const struct wim_lookup_table *table);

extern u64
lookup_table_total_stream_size(struct wim_lookup_table *table);


static inline void
lookup_table_insert_unhashed(struct wim_lookup_table *table,
                             struct wim_lookup_table_entry *lte,
                             struct wim_inode *back_inode,
                             u32 back_stream_id)
{
        lte->unhashed = 1;
        lte->back_inode = back_inode;
        lte->back_stream_id = back_stream_id;
        list_add_tail(&lte->unhashed_list, table->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 */