[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

/* Not yet used */
//#define LOOKUP_FLAG_FOLLOW_SYMLINKS   0x00000004


/* A lookup table that is used to translate the hash codes of dentries into the
 * offsets and sizes of uncompressed or compressed file resources.  It is
 * implemented as a hash table. */
struct lookup_table {
        struct hlist_head *array;
        u64 num_entries;
        u64 capacity;
};

struct wimlib_fd;

#ifdef WITH_NTFS_3G
struct ntfs_location {
        char *path_utf8;
        char *stream_name_utf16;
        u16 stream_name_utf16_num_chars;
        struct _ntfs_volume **ntfs_vol_p;
        bool is_reparse_point;
};
#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 lookup_table_entry {

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

        /* An enumerated type that identifies where the stream corresponding to
         * this lookup table entry is actually located.
         *
         * Obviously 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 {
                /* 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_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;
        };

        /* Pointers to somewhere where the stream is actually located.  See the
         * comments for the @resource_location field above. */
        union {
                WIMStruct *wim;
                char *file_on_disk;
                char *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 inode *lte_inode;
        };
#ifdef WITH_FUSE
        u16 num_opened_fds;
#endif

        /* 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;

        /* 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;

        /* 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.  */
        char *extracted_file;

        union {
                /* List of lookup table entries that correspond to streams that have
                 * been extracted to the staging directory when modifying a read-write
                 * mounted WIM. */
                struct list_head staging_list;

                /* Temporary field for creating a singly linked list. */
                struct lookup_table_entry *next_lte_in_swm;
        };
};

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

static inline u64
wim_resource_compressed_size(const struct 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 lookup_table_entry *lte)
{
        if (!(lte->resource_entry.flags & WIM_RESHDR_FLAG_COMPRESSED)
            || lte->resource_location != RESOURCE_IN_WIM)
                return WIM_COMPRESSION_TYPE_NONE;
        return wimlib_get_compression_type(lte->wim);
}


extern struct lookup_table *new_lookup_table(size_t capacity);

extern void lookup_table_insert(struct lookup_table *table,
                                struct lookup_table_entry *lte);

/* Unlinks a lookup table entry from the table; does not free it. */
static inline void lookup_table_unlink(struct lookup_table *table,
                                       struct lookup_table_entry *lte)
{
        hlist_del(&lte->hash_list);
        table->num_entries--;
}

extern struct lookup_table_entry *new_lookup_table_entry();

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

extern int for_lookup_table_entry(struct lookup_table *table,
                                  int (*visitor)(struct lookup_table_entry *, void *),
                                  void *arg);

extern struct lookup_table_entry *
__lookup_resource(const struct lookup_table *table, const u8 hash[]);

extern int lookup_resource(WIMStruct *w, const char *path,
                           int lookup_flags, struct dentry **dentry_ret,
                           struct lookup_table_entry **lte_ret,
                           u16 *stream_idx_ret);

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

extern int lte_zero_out_refcnt(struct lookup_table_entry *entry, void *ignore);
extern int lte_zero_real_refcnt(struct lookup_table_entry *entry, void *ignore);
extern int lte_free_extracted_file(struct lookup_table_entry *lte, void *ignone);

extern void print_lookup_table_entry(const struct lookup_table_entry *entry);

extern int read_lookup_table(WIMStruct *w);

extern void free_lookup_table(struct lookup_table *table);

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

extern void free_lookup_table_entry(struct lookup_table_entry *lte);

extern int dentry_resolve_ltes(struct dentry *dentry, void *__table);
extern int dentry_unresolve_ltes(struct dentry *dentry, void *ignore);

/* Writes the lookup table to the output file. */
static inline int write_lookup_table(struct lookup_table *table, FILE *out)
{
        return for_lookup_table_entry(table, write_lookup_table_entry, out);
}

/* Unlinks and frees an entry from a lookup table. */
static inline void lookup_table_remove(struct lookup_table *table,
                                       struct lookup_table_entry *lte)
{
        lookup_table_unlink(table, lte);
        free_lookup_table_entry(lte);
}

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 lookup_table_entry *
inode_stream_lte_resolved(const struct inode *inode, unsigned stream_idx)
{
        wimlib_assert(inode->resolved);
        wimlib_assert(stream_idx <= inode->num_ads);
        if (stream_idx == 0)
                return inode->lte;
        else
                return inode->ads_entries[stream_idx - 1].lte;
}

static inline struct lookup_table_entry *
inode_stream_lte_unresolved(const struct inode *inode, unsigned stream_idx,
                            const struct lookup_table *table)
{
        wimlib_assert(!inode->resolved);
        wimlib_assert(stream_idx <= inode->num_ads);
        if (!table)
                return NULL;
        if (stream_idx == 0)
                return __lookup_resource(table, inode->hash);
        else
                return __lookup_resource(table,
                                         inode->ads_entries[
                                                stream_idx - 1].hash);
}
/*
 * Returns the lookup table entry 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 struct lookup_table_entry *
inode_stream_lte(const struct inode *inode, unsigned stream_idx,
                 const struct lookup_table *table)
{
        if (inode->resolved)
                return inode_stream_lte_resolved(inode, stream_idx);
        else
                return inode_stream_lte_unresolved(inode, stream_idx, table);
}


static inline const u8 *inode_stream_hash_unresolved(const struct inode *inode,
                                                     unsigned stream_idx)
{
        wimlib_assert(!inode->resolved);
        wimlib_assert(stream_idx <= inode->num_ads);
        if (stream_idx == 0)
                return inode->hash;
        else
                return inode->ads_entries[stream_idx - 1].hash;
}


static inline const u8 *inode_stream_hash_resolved(const struct inode *inode,
                                                   unsigned stream_idx)
{
        struct 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 inode *inode,
                                          unsigned stream_idx)
{
        if (inode->resolved)
                return inode_stream_hash_resolved(inode, stream_idx);
        else
                return inode_stream_hash_unresolved(inode, stream_idx);
}

static inline u16 inode_stream_name_len(const struct inode *inode,
                                        unsigned stream_idx)
{
        wimlib_assert(stream_idx <= inode->num_ads);
        if (stream_idx == 0)
                return 0;
        else
                return inode->ads_entries[stream_idx - 1].stream_name_len;
}

static inline struct lookup_table_entry *
inode_unnamed_lte_resolved(const struct inode *inode)
{
        wimlib_assert(inode->resolved);
        for (unsigned i = 0; i <= inode->num_ads; i++)
                if (inode_stream_name_len(inode, i) == 0 &&
                     !is_zero_hash(inode_stream_hash_resolved(inode, i)))
                        return inode_stream_lte_resolved(inode, i);
        return NULL;
}

static inline struct lookup_table_entry *
inode_unnamed_lte_unresolved(const struct inode *inode,
                             const struct lookup_table *table)
{
        wimlib_assert(!inode->resolved);
        for (unsigned i = 0; i <= inode->num_ads; i++)
                if (inode_stream_name_len(inode, i) == 0 &&
                     !is_zero_hash(inode_stream_hash_unresolved(inode, i)))
                        return inode_stream_lte_unresolved(inode, i, table);
        return NULL;
}

extern struct lookup_table_entry *
inode_unnamed_lte(const struct inode *inode,
                  const struct lookup_table *table);


#endif