[wimlib] / src / lookup_table.h

#ifndef _WIMLIB_LOOKUP_TABLE_H
#define _WIMLIB_LOOKUP_TABLE_H
#include "wimlib_internal.h"
#include "dentry.h"
#include "sha1.h"
#include <sys/types.h>

/* Size of each lookup table entry in the WIM file. */
#define WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE 50

#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;
};

#ifdef WITH_NTFS_3G
struct ntfs_location {
        mbchar *path;
        utf16lechar *stream_name;
        u16 stream_name_nchars;
        struct _ntfs_volume **ntfs_vol_p;
        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. */
        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.  In addition, if
         * @file_on_disk_fp is not NULL, it will be an open FILE * to the file.
         * */
        RESOURCE_IN_FILE_ON_DISK,

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

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

        /* 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,

        /* Resource must be accessed using Win32 API (may be a named data
         * stream) */
        RESOURCE_WIN32,
};

/*
 * 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;

        /* See enum resource_location above */
        u16 resource_location;

        /* (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;
        };

        union {
                #ifdef WITH_FUSE
                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.  */
                mbchar *extracted_file;
        };

        /* Pointers to somewhere where the stream is actually located.  See the
         * comments for the @resource_location field above. */
        union {
                WIMStruct *wim;
                mbchar *file_on_disk;
                mbchar *staging_file_name;
                u8 *attached_buffer;
        #ifdef WITH_NTFS_3G
                struct ntfs_location *ntfs_loc;
        #endif
        };
        union {
                /* @file_on_disk_fp and @attr are both used to cache file/stream
                 * handles so we don't have re-open them on every read */

                /* Valid iff resource_location == RESOURCE_IN_FILE_ON_DISK */
                FILE *file_on_disk_fp;
        #ifdef WITH_NTFS_3G
                /* Valid iff resource_location == RESOURCE_IN_NTFS_VOLUME */
                struct _ntfs_attr *attr;
        #endif

                /* Pointer to inode that contains the opened file descriptors to
                 * this stream (valid iff resource_location ==
                 * RESOURCE_IN_STAGING_FILE) */
                struct wim_inode *lte_inode;
        };

        /* When a WIM file is written, out_refcnt starts at 0 and is incremented
         * whenever the file resource pointed to by this lookup table entry
         * needs to be written.  The file resource only need to be written when
         * out_refcnt is nonzero, since otherwise it is not referenced by any
         * dentries. */
        u32 out_refcnt;

        u32 real_refcnt;

        union {
                /* 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;

                struct list_head msg_list;
                struct list_head inode_list;
        };

        /* List of lookup table entries that correspond to streams that have
         * been extracted to the staging directory when modifying a read-write
         * mounted WIM.
         *
         * This field is also used to make other lists of lookup table entries.
         * */
        struct list_head staging_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 (wim_resource_size(lte) + WIM_CHUNK_SIZE - 1) / WIM_CHUNK_SIZE;
}

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

/*
 * XXX Probably should store the compression type directly in the lookup table
 * entry
 */
static inline int
wim_resource_compression_type(const struct wim_lookup_table_entry *lte)
{
        if (!(lte->resource_entry.flags & WIM_RESHDR_FLAG_COMPRESSED)
            || lte->resource_location != RESOURCE_IN_WIM)
                return WIMLIB_COMPRESSION_TYPE_NONE;
        return wimlib_get_compression_type(lte->wim);
}


extern struct wim_lookup_table *
new_lookup_table(size_t capacity);

extern int
read_lookup_table(WIMStruct *w);

extern int
write_lookup_table(struct wim_lookup_table *table, FILE *out,
                   struct resource_entry *out_res_entry);
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)
{
        hlist_del(&lte->hash_list);
        table->num_entries--;
}

extern struct wim_lookup_table_entry *
new_lookup_table_entry();

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

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 int
for_lookup_table_entry(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 *w, const mbchar *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
inode_resolve_ltes(struct wim_inode *inode, struct wim_lookup_table *table);

extern void
inode_unresolve_ltes(struct wim_inode *inode);

extern int
write_lookup_table_entry(struct wim_lookup_table_entry *lte, void *__out);

static inline struct resource_entry*
wim_metadata_resource_entry(WIMStruct *w)
{
        return &w->image_metadata[
                        w->current_image - 1].metadata_lte->resource_entry;
}

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;
}

static inline struct wim_lookup_table_entry *
inode_unnamed_lte_resolved(const struct wim_inode *inode)
{
        wimlib_assert(inode->i_resolved);
        for (unsigned i = 0; i <= inode->i_num_ads; i++) {
                if (inode_stream_name_nbytes(inode, i) == 0 &&
                    !is_zero_hash(inode_stream_hash_resolved(inode, i)))
                {
                        return inode_stream_lte_resolved(inode, i);
                }
        }
        return NULL;
}

static inline struct wim_lookup_table_entry *
inode_unnamed_lte_unresolved(const struct wim_inode *inode,
                             const struct wim_lookup_table *table)
{
        wimlib_assert(!inode->i_resolved);
        for (unsigned i = 0; i <= inode->i_num_ads; i++) {
                if (inode_stream_name_nbytes(inode, i) == 0 &&
                    !is_zero_hash(inode_stream_hash_unresolved(inode, i)))
                {
                        return inode_stream_lte_unresolved(inode, i, table);
                }
        }
        return NULL;
}

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);

#endif