[wimlib] / src / dentry.c

/*
 * dentry.c
 *
 * A dentry (directory entry) contains the metadata for a file.  In the WIM file
 * format, the dentries are stored in the "metadata resource" section right
 * after the security data.  Each image in the WIM file has its own metadata
 * resource with its own security data and dentry tree.  Dentries in different
 * images may share file resources by referring to the same lookup table
 * entries.
 */

/*
 *
 * Copyright (C) 2010 Carl Thijssen
 * Copyright (C) 2012 Eric Biggers
 *
 * This file is part of wimlib, a library for working with WIM files.
 *
 * wimlib is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with wimlib; if not, see http://www.gnu.org/licenses/.
 */

#include "wimlib_internal.h"
#include "dentry.h"
#include "io.h"
#include "timestamp.h"
#include "lookup_table.h"
#include "sha1.h"
#include <unistd.h>
#include <sys/stat.h>

/*
 * Returns true if @dentry has the UTF-8 file name @name that has length
 * @name_len.
 */
static bool dentry_has_name(const struct dentry *dentry, const char *name, 
                            size_t name_len)
{
        if (dentry->file_name_utf8_len != name_len)
                return false;
        return memcmp(dentry->file_name_utf8, name, name_len) == 0;
}

/* Real length of a dentry, including the alternate data stream entries, which
 * are not included in the dentry->length field... */
u64 dentry_total_length(const struct dentry *dentry)
{
        u64 length = (dentry->length + 7) & ~7;
        for (u16 i = 0 ; i < dentry->num_ads; i++)
                length += ads_entry_length(&dentry->ads_entries[i]);
        return length;
}

/* Transfers file attributes from a `stat' buffer to a struct dentry. */
void stbuf_to_dentry(const struct stat *stbuf, struct dentry *dentry)
{
        if (S_ISLNK(stbuf->st_mode)) {
                dentry->attributes = FILE_ATTRIBUTE_REPARSE_POINT;
                dentry->reparse_tag = WIM_IO_REPARSE_TAG_SYMLINK;
        } else if (S_ISDIR(stbuf->st_mode)) {
                dentry->attributes = FILE_ATTRIBUTE_DIRECTORY;
        } else {
                dentry->attributes = FILE_ATTRIBUTE_NORMAL;
        }
        if (sizeof(ino_t) >= 8)
                dentry->hard_link = (u64)stbuf->st_ino;
        else
                dentry->hard_link = (u64)stbuf->st_ino |
                                   ((u64)stbuf->st_dev << (sizeof(ino_t) * 8));
}

/* Transfers file attributes from a struct dentry to a `stat' buffer. */
void dentry_to_stbuf(const struct dentry *dentry, struct stat *stbuf, 
                     const struct lookup_table *table)
{
        struct lookup_table_entry *lte;



        if (dentry_is_symlink(dentry))
                stbuf->st_mode = S_IFLNK | 0777;
        else if (dentry_is_directory(dentry))
                stbuf->st_mode = S_IFDIR | 0755;
        else
                stbuf->st_mode = S_IFREG | 0644;

        stbuf->st_ino   = dentry->hard_link;
        stbuf->st_nlink = dentry_link_group_size(dentry);
        stbuf->st_uid   = getuid();
        stbuf->st_gid   = getgid();

        /* Use the size of the unnamed (default) file stream. */
        if (table && (lte = __lookup_resource(table, dentry_hash(dentry)))) {
                if (lte->staging_file_name) {
                        struct stat native_stat;
                        stat(lte->staging_file_name, &native_stat);
                        stbuf->st_size = native_stat.st_size;
                } else {
                        stbuf->st_size = lte->resource_entry.original_size;
                }
        } else {
                stbuf->st_size = 0;
        }

        stbuf->st_atime   = ms_timestamp_to_unix(dentry->last_access_time);
        stbuf->st_mtime   = ms_timestamp_to_unix(dentry->last_write_time);
        stbuf->st_ctime   = ms_timestamp_to_unix(dentry->creation_time);
        stbuf->st_blocks  = (stbuf->st_size + 511) / 512;
}

/* Makes all timestamp fields for the dentry be the current time. */
void dentry_update_all_timestamps(struct dentry *dentry)
{
        u64 now = get_timestamp();
        dentry->creation_time    = now;
        dentry->last_access_time = now;
        dentry->last_write_time  = now;
}

struct ads_entry *dentry_get_ads_entry(struct dentry *dentry,
                                       const char *stream_name)
{
        size_t stream_name_len = strlen(stream_name);
        if (!stream_name)
                return NULL;
        for (u16 i = 0; i < dentry->num_ads; i++)
                if (ads_entry_has_name(&dentry->ads_entries[i],
                                       stream_name, stream_name_len))
                        return &dentry->ads_entries[i];
        return NULL;
}

/* Add an alternate stream entry to a dentry and return a pointer to it, or NULL
 * on failure. */
struct ads_entry *dentry_add_ads(struct dentry *dentry, const char *stream_name)
{
        u16 num_ads = dentry->num_ads + 1;
        struct ads_entry *ads_entries;
        struct ads_entry *new_entry;
        if (num_ads == 0xffff)
                return NULL;
        ads_entries = MALLOC(num_ads * sizeof(struct ads_entry));
        if (!ads_entries)
                return NULL;

        new_entry = &ads_entries[num_ads - 1];
        if (change_ads_name(new_entry, stream_name) != 0) {
                FREE(ads_entries);
                return NULL;
        }

        memcpy(ads_entries, dentry->ads_entries,
               (num_ads - 1) * sizeof(struct ads_entry));
        FREE(dentry->ads_entries);
        dentry->ads_entries = ads_entries;
        dentry->num_ads = num_ads;
        return memset(new_entry, 0, sizeof(struct ads_entry));
}

void dentry_remove_ads(struct dentry *dentry, struct ads_entry *sentry)
{
        destroy_ads_entry(sentry);
        memcpy(sentry, sentry + 1,
               (dentry->num_ads - (sentry - dentry->ads_entries + 1))
                 * sizeof(struct ads_entry));
        dentry->num_ads--;
}

/* 
 * Calls a function on all directory entries in a directory tree.  It is called
 * on a parent before its children.
 */
int for_dentry_in_tree(struct dentry *root, 
                       int (*visitor)(struct dentry*, void*), void *arg)
{
        int ret;
        struct dentry *child;

        ret = visitor(root, arg);

        if (ret != 0)
                return ret;

        child = root->children;

        if (!child)
                return 0;

        do {
                ret = for_dentry_in_tree(child, visitor, arg);
                if (ret != 0)
                        return ret;
                child = child->next;
        } while (child != root->children);
        return 0;
}

/* 
 * Like for_dentry_in_tree(), but the visitor function is always called on a
 * dentry's children before on itself.
 */
int for_dentry_in_tree_depth(struct dentry *root, 
                             int (*visitor)(struct dentry*, void*), void *arg)
{
        int ret;
        struct dentry *child;
        struct dentry *next;

        child = root->children;
        if (child) {
                do {
                        next = child->next;
                        ret = for_dentry_in_tree_depth(child, visitor, arg);
                        if (ret != 0)
                                return ret;
                        child = next;
                } while (child != root->children);
        }
        return visitor(root, arg);
}

/* 
 * Calculate the full path of @dentry, based on its parent's full path and on
 * its UTF-8 file name. 
 */
int calculate_dentry_full_path(struct dentry *dentry, void *ignore)
{
        char *full_path;
        u32 full_path_len;
        if (dentry_is_root(dentry)) {
                full_path = MALLOC(2);
                if (!full_path)
                        goto oom;
                full_path[0] = '/';
                full_path[1] = '\0';
                full_path_len = 1;
        } else {
                char *parent_full_path;
                u32 parent_full_path_len;
                const struct dentry *parent = dentry->parent;

                if (dentry_is_root(parent)) {
                        parent_full_path = "";
                        parent_full_path_len = 0;
                } else {
                        parent_full_path = parent->full_path_utf8;
                        parent_full_path_len = parent->full_path_utf8_len;
                }

                full_path_len = parent_full_path_len + 1 +
                                dentry->file_name_utf8_len;
                full_path = MALLOC(full_path_len + 1);
                if (!full_path)
                        goto oom;

                memcpy(full_path, parent_full_path, parent_full_path_len);
                full_path[parent_full_path_len] = '/';
                memcpy(full_path + parent_full_path_len + 1,
                       dentry->file_name_utf8,
                       dentry->file_name_utf8_len);
                full_path[full_path_len] = '\0';
        }
        FREE(dentry->full_path_utf8);
        dentry->full_path_utf8 = full_path;
        dentry->full_path_utf8_len = full_path_len;
        return 0;
oom:
        ERROR("Out of memory while calculating dentry full path");
        return WIMLIB_ERR_NOMEM;
}

/* 
 * Recursively calculates the subdir offsets for a directory tree. 
 *
 * @dentry:  The root of the directory tree.
 * @subdir_offset_p:  The current subdirectory offset; i.e., the subdirectory
 *      offset for @dentry. 
 */
void calculate_subdir_offsets(struct dentry *dentry, u64 *subdir_offset_p)
{
        struct dentry *child;

        child = dentry->children;
        dentry->subdir_offset = *subdir_offset_p;
        if (child) {

                /* Advance the subdir offset by the amount of space the children
                 * of this dentry take up. */
                do {
                        *subdir_offset_p += dentry_total_length(child);
                        child = child->next;
                } while (child != dentry->children);

                /* End-of-directory dentry on disk. */
                *subdir_offset_p += 8;

                /* Recursively call calculate_subdir_offsets() on all the
                 * children. */
                do {
                        calculate_subdir_offsets(child, subdir_offset_p);
                        child = child->next;
                } while (child != dentry->children);
        } else {
                /* On disk, childless directories have a valid subdir_offset
                 * that points to an 8-byte end-of-directory dentry.  Regular
                 * files have a subdir_offset of 0. */
                if (dentry_is_directory(dentry))
                        *subdir_offset_p += 8;
                else
                        dentry->subdir_offset = 0;
        }
}


/* Returns the child of @dentry that has the file name @name.  
 * Returns NULL if no child has the name. */
struct dentry *get_dentry_child_with_name(const struct dentry *dentry, 
                                                        const char *name)
{
        struct dentry *child;
        size_t name_len;
        
        child = dentry->children;
        if (child) {
                name_len = strlen(name);
                do {
                        if (dentry_has_name(child, name, name_len))
                                return child;
                        child = child->next;
                } while (child != dentry->children);
        }
        return NULL;
}

/* Retrieves the dentry that has the UTF-8 @path relative to the dentry
 * @cur_dir.  Returns NULL if no dentry having the path is found. */
static struct dentry *get_dentry_relative_path(struct dentry *cur_dir, const char *path)
{
        struct dentry *child;
        size_t base_len;
        const char *new_path;

        if (*path == '\0')
                return cur_dir;

        child = cur_dir->children;
        if (child) {
                new_path = path_next_part(path, &base_len);
                do {
                        if (dentry_has_name(child, path, base_len))
                                return get_dentry_relative_path(child, new_path);
                        child = child->next;
                } while (child != cur_dir->children);
        }
        return NULL;
}

/* Returns the dentry corresponding to the UTF-8 @path, or NULL if there is no
 * such dentry. */
struct dentry *get_dentry(WIMStruct *w, const char *path)
{
        struct dentry *root = wim_root_dentry(w);
        while (*path == '/')
                path++;
        return get_dentry_relative_path(root, path);
}

/* Returns the parent directory for the @path. */
struct dentry *get_parent_dentry(WIMStruct *w, const char *path)
{
        size_t path_len = strlen(path);
        char buf[path_len + 1];

        memcpy(buf, path, path_len + 1);

        to_parent_name(buf, path_len);

        return get_dentry(w, buf);
}

/* Prints the full path of a dentry. */
int print_dentry_full_path(struct dentry *dentry, void *ignore)
{
        if (dentry->full_path_utf8)
                puts(dentry->full_path_utf8);
        return 0;
}

struct file_attr_flag {
        u32 flag;
        const char *name;
};
struct file_attr_flag file_attr_flags[] = {
        {FILE_ATTRIBUTE_READONLY,               "READONLY"},
        {FILE_ATTRIBUTE_HIDDEN,         "HIDDEN"},
        {FILE_ATTRIBUTE_SYSTEM,         "SYSTEM"},
        {FILE_ATTRIBUTE_DIRECTORY,              "DIRECTORY"},
        {FILE_ATTRIBUTE_ARCHIVE,                "ARCHIVE"},
        {FILE_ATTRIBUTE_DEVICE,         "DEVICE"},
        {FILE_ATTRIBUTE_NORMAL,         "NORMAL"},
        {FILE_ATTRIBUTE_TEMPORARY,              "TEMPORARY"},
        {FILE_ATTRIBUTE_SPARSE_FILE,    "SPARSE_FILE"},
        {FILE_ATTRIBUTE_REPARSE_POINT,  "REPARSE_POINT"},
        {FILE_ATTRIBUTE_COMPRESSED,             "COMPRESSED"},
        {FILE_ATTRIBUTE_OFFLINE,                "OFFLINE"},
        {FILE_ATTRIBUTE_NOT_CONTENT_INDEXED,"NOT_CONTENT_INDEXED"},
        {FILE_ATTRIBUTE_ENCRYPTED,              "ENCRYPTED"},
        {FILE_ATTRIBUTE_VIRTUAL,                "VIRTUAL"},
};

/* Prints a directory entry.  @lookup_table is a pointer to the lookup table, or
 * NULL if the resource entry for the dentry is not to be printed. */
int print_dentry(struct dentry *dentry, void *lookup_table)
{
        struct lookup_table_entry *lte;
        unsigned i;

        printf("[DENTRY]\n");
        printf("Length            = %"PRIu64"\n", dentry->length);
        printf("Attributes        = 0x%x\n", dentry->attributes);
        for (i = 0; i < ARRAY_LEN(file_attr_flags); i++)
                if (file_attr_flags[i].flag & dentry->attributes)
                        printf("    FILE_ATTRIBUTE_%s is set\n",
                                file_attr_flags[i].name);
        printf("Security ID       = %d\n", dentry->security_id);
        printf("Subdir offset     = %"PRIu64"\n", dentry->subdir_offset);
        /*printf("Unused1           = 0x%"PRIu64"\n", dentry->unused1);*/
        /*printf("Unused2           = %"PRIu64"\n", dentry->unused2);*/
        printf("Creation Time     = 0x%"PRIx64"\n", dentry->creation_time);
        printf("Last Access Time  = 0x%"PRIx64"\n", dentry->last_access_time);
        printf("Last Write Time   = 0x%"PRIx64"\n", dentry->last_write_time);
        printf("Hash              = 0x"); 
        print_hash(dentry->hash); 
        putchar('\n');
        printf("Reparse Tag       = 0x%"PRIx32"\n", dentry->reparse_tag);
        printf("Hard Link Group   = 0x%"PRIx64"\n", dentry->hard_link);
        printf("Number of Alternate Data Streams = %hu\n", dentry->num_ads);
        printf("Filename          = \"");
        print_string(dentry->file_name, dentry->file_name_len);
        puts("\"");
        printf("Filename Length   = %hu\n", dentry->file_name_len);
        printf("Filename (UTF-8)  = \"%s\"\n", dentry->file_name_utf8);
        printf("Filename (UTF-8) Length = %hu\n", dentry->file_name_utf8_len);
        printf("Short Name        = \"");
        print_string(dentry->short_name, dentry->short_name_len);
        puts("\"");
        printf("Short Name Length = %hu\n", dentry->short_name_len);
        printf("Full Path (UTF-8) = \"%s\"\n", dentry->full_path_utf8);
        if (lookup_table && (lte = __lookup_resource(lookup_table, dentry->hash)))
                print_lookup_table_entry(lte, NULL);
        else
                putchar('\n');
        for (u16 i = 0; i < dentry->num_ads; i++) {
                printf("[Alternate Stream Entry %u]\n", i);
                printf("Name = \"%s\"\n", dentry->ads_entries[i].stream_name_utf8);
                printf("Name Length (UTF-16) = %u\n",
                                dentry->ads_entries[i].stream_name_len);
                printf("Hash              = 0x"); 
                print_hash(dentry->ads_entries[i].hash); 
                if (lookup_table &&
                     (lte = __lookup_resource(lookup_table,
                                              dentry->ads_entries[i].hash)))
                {
                        print_lookup_table_entry(lte, NULL);
                } else {
                        putchar('\n');
                }
        }
        return 0;
}

static inline void dentry_common_init(struct dentry *dentry)
{
        memset(dentry, 0, sizeof(struct dentry));
        dentry->refcnt = 1;
        dentry->security_id = -1;
        dentry->link_group_master_status = GROUP_SLAVE;
}

/* 
 * Creates an unlinked directory entry.
 *
 * @name:    The base name of the new dentry.
 * @return:  A pointer to the new dentry, or NULL if out of memory.
 */
struct dentry *new_dentry(const char *name)
{
        struct dentry *dentry;
        
        dentry = MALLOC(sizeof(struct dentry));
        if (!dentry)
                goto err;

        dentry_common_init(dentry);
        if (change_dentry_name(dentry, name) != 0)
                goto err;

        dentry_update_all_timestamps(dentry);
        dentry->next   = dentry;
        dentry->prev   = dentry;
        dentry->parent = dentry;
        INIT_LIST_HEAD(&dentry->link_group_list);
        return dentry;
err:
        FREE(dentry);
        ERROR("Failed to allocate new dentry");
        return NULL;
}

void dentry_free_ads_entries(struct dentry *dentry)
{
        for (u16 i = 0; i < dentry->num_ads; i++)
                destroy_ads_entry(&dentry->ads_entries[i]);
        FREE(dentry->ads_entries);
        dentry->ads_entries = NULL;
        dentry->num_ads = 0;
}

static void __destroy_dentry(struct dentry *dentry)
{
        FREE(dentry->file_name);
        FREE(dentry->file_name_utf8);
        FREE(dentry->short_name);
        FREE(dentry->full_path_utf8);
}

void free_dentry(struct dentry *dentry)
{
        __destroy_dentry(dentry);
        if (dentry->link_group_master_status != GROUP_SLAVE)
                dentry_free_ads_entries(dentry);
        FREE(dentry);
}

void put_dentry(struct dentry *dentry)
{
        if (dentry->link_group_master_status == GROUP_MASTER) {
                struct dentry *new_master;
                list_for_each_entry(new_master, &dentry->link_group_list,
                                    link_group_list)
                {
                        if (new_master->link_group_master_status == GROUP_SLAVE) {
                                new_master->link_group_master_status = GROUP_MASTER;
                                dentry->link_group_master_status = GROUP_SLAVE;
                                break;
                        }
                }
        }
        list_del(&dentry->link_group_list);
        free_dentry(dentry);
}

static bool dentries_have_same_ads(const struct dentry *d1,
                                   const struct dentry *d2)
{
        /* Verify stream names and hashes are the same */
        for (u16 i = 0; i < d1->num_ads; i++) {
                if (strcmp(d1->ads_entries[i].stream_name_utf8,
                           d2->ads_entries[i].stream_name_utf8) != 0)
                        return false;
                if (memcmp(d1->ads_entries[i].hash,
                           d2->ads_entries[i].hash,
                           WIM_HASH_SIZE) != 0)
                        return false;
        }
        return true;
}

/* Share the alternate stream entries between hard-linked dentries. */
int share_dentry_ads(struct dentry *master, struct dentry *slave)
{
        const char *mismatch_type;
        wimlib_assert(master->num_ads == 0 ||
                      master->ads_entries != slave->ads_entries);
        if (master->attributes != slave->attributes) {
                mismatch_type = "attributes";
                goto mismatch;
        }
        if (master->attributes & FILE_ATTRIBUTE_DIRECTORY) {
                ERROR("`%s' is hard-linked to `%s', which is a directory ",
                      slave->full_path_utf8, master->full_path_utf8);
                return WIMLIB_ERR_INVALID_DENTRY;
        }
        if (master->security_id != slave->security_id) {
                mismatch_type = "security ID";
                goto mismatch;
        }
        if (memcmp(master->hash, slave->hash, WIM_HASH_SIZE) != 0) {
                mismatch_type = "main file resource";
                goto mismatch;
        }
        if (!dentries_have_same_ads(master, slave)) {
                mismatch_type = "Alternate Stream Entries";
                goto mismatch;
        }
        dentry_free_ads_entries(slave);
        slave->ads_entries = master->ads_entries;
        slave->link_group_master_status = GROUP_SLAVE;
        return 0;
mismatch:
        ERROR("Dentries `%s' and `%s' in the same hard-link group but "
              "do not share the same %s",
              master->full_path_utf8, slave->full_path_utf8,
              mismatch_type);
        return WIMLIB_ERR_INVALID_DENTRY;
}

/* clones a dentry.
 *
 * Beware:
 *      - memory for file names is not cloned
 *      - next, prev, and children pointers and not touched
 *      - stream entries are not cloned.
 */
struct dentry *clone_dentry(struct dentry *old)
{
        struct dentry *new = MALLOC(sizeof(struct dentry));
        if (!new)
                return NULL;
        memcpy(new, old, sizeof(struct dentry));
        new->file_name          = NULL;
        new->file_name_len      = 0;
        new->file_name_utf8     = NULL;
        new->file_name_utf8_len = 0;
        new->short_name         = NULL;
        new->short_name_len     = 0;
        return new;
}

/* Arguments for do_free_dentry(). */
struct free_dentry_args {
        struct lookup_table *lookup_table;
        bool lt_decrement_refcnt;
};

/* 
 * This function is passed as an argument to for_dentry_in_tree_depth() in order
 * to free a directory tree.  __args is a pointer to a `struct free_dentry_args'.
 */
static int do_free_dentry(struct dentry *dentry, void *__args)
{
        struct free_dentry_args *args = (struct free_dentry_args*)__args;

        if (args->lt_decrement_refcnt && !dentry_is_directory(dentry)) {
                lookup_table_decrement_refcnt(args->lookup_table, 
                                              dentry->hash);
        }

        wimlib_assert(dentry->refcnt >= 1);
        if (--dentry->refcnt == 0)
                free_dentry(dentry);
        return 0;
}

/* 
 * Unlinks and frees a dentry tree.
 *
 * @root:               The root of the tree.
 * @lookup_table:       The lookup table for dentries.
 * @decrement_refcnt:   True if the dentries in the tree are to have their 
 *                      reference counts in the lookup table decremented.
 */
void free_dentry_tree(struct dentry *root, struct lookup_table *lookup_table, 
                      bool lt_decrement_refcnt)
{
        if (!root || !root->parent)
                return;

        struct free_dentry_args args;
        args.lookup_table        = lookup_table;
        args.lt_decrement_refcnt = lt_decrement_refcnt;
        for_dentry_in_tree_depth(root, do_free_dentry, &args);
}

int increment_dentry_refcnt(struct dentry *dentry, void *ignore)
{
        dentry->refcnt++;
        return 0;
}

/* 
 * Links a dentry into the directory tree.
 *
 * @dentry: The dentry to link.
 * @parent: The dentry that will be the parent of @dentry.
 */
void link_dentry(struct dentry *dentry, struct dentry *parent)
{
        dentry->parent = parent;
        if (parent->children) {
                /* Not an only child; link to siblings. */
                dentry->next = parent->children;
                dentry->prev = parent->children->prev;
                dentry->next->prev = dentry;
                dentry->prev->next = dentry;
        } else {
                /* Only child; link to parent. */
                parent->children = dentry;
                dentry->next = dentry;
                dentry->prev = dentry;
        }
}


/* Unlink a dentry from the directory tree. 
 *
 * Note: This merely removes it from the in-memory tree structure.  See
 * remove_dentry() in mount.c for a function implemented on top of this one that
 * frees the dentry and implements reference counting for the lookup table
 * entries. */
void unlink_dentry(struct dentry *dentry)
{
        if (dentry_is_root(dentry))
                return;
        if (dentry_is_only_child(dentry)) {
                dentry->parent->children = NULL;
        } else {
                if (dentry_is_first_sibling(dentry))
                        dentry->parent->children = dentry->next;
                dentry->next->prev = dentry->prev;
                dentry->prev->next = dentry->next;
        }
}


/* Recalculates the length of @dentry based on its file name length and short
 * name length.  */
static inline void recalculate_dentry_size(struct dentry *dentry)
{
        dentry->length = WIM_DENTRY_DISK_SIZE + dentry->file_name_len + 
                         2 + dentry->short_name_len;
        /* Must be multiple of 8. */
        dentry->length = (dentry->length + 7) & ~7;
}

int get_names(char **name_utf16_ret, char **name_utf8_ret,
              u16 *name_utf16_len_ret, u16 *name_utf8_len_ret,
              const char *name)
{
        size_t utf8_len;
        size_t utf16_len;
        char *name_utf16, *name_utf8;

        utf8_len = strlen(name);

        name_utf16 = utf8_to_utf16(name, utf8_len, &utf16_len);

        if (!name_utf16)
                return WIMLIB_ERR_NOMEM;

        name_utf8 = MALLOC(utf8_len + 1);
        if (!name_utf8) {
                FREE(name_utf8);
                return WIMLIB_ERR_NOMEM;
        }
        memcpy(name_utf8, name, utf8_len + 1);
        FREE(*name_utf8_ret);
        FREE(*name_utf16_ret);
        *name_utf8_ret      = name_utf8;
        *name_utf16_ret     = name_utf16;
        *name_utf8_len_ret  = utf8_len;
        *name_utf16_len_ret = utf16_len;
        return 0;
}

/* Changes the name of a dentry to @new_name.  Only changes the file_name and
 * file_name_utf8 fields; does not change the short_name, short_name_utf8, or
 * full_path_utf8 fields.  Also recalculates its length. */
int change_dentry_name(struct dentry *dentry, const char *new_name)
{
        int ret;

        ret = get_names(&dentry->file_name, &dentry->file_name_utf8,
                        &dentry->file_name_len, &dentry->file_name_utf8_len,
                         new_name);
        if (ret == 0)
                recalculate_dentry_size(dentry);
        return ret;
}

int change_ads_name(struct ads_entry *entry, const char *new_name)
{
        return get_names(&entry->stream_name, &entry->stream_name_utf8,
                         &entry->stream_name_len,
                         &entry->stream_name_utf8_len,
                          new_name);
}

/* Parameters for calculate_dentry_statistics(). */
struct image_statistics {
        struct lookup_table *lookup_table;
        u64 *dir_count;
        u64 *file_count;
        u64 *total_bytes;
        u64 *hard_link_bytes;
};

static int calculate_dentry_statistics(struct dentry *dentry, void *arg)
{
        struct image_statistics *stats;
        struct lookup_table_entry *lte; 
        u16 i;
        
        stats = arg;

        if (dentry_is_directory(dentry) && !dentry_is_root(dentry))
                ++*stats->dir_count;
        else
                ++*stats->file_count;

        lte = __lookup_resource(stats->lookup_table, dentry->hash);
        i = 0;
        while (1) {
                if (lte) {
                        u64 size = lte->resource_entry.original_size;
                        *stats->total_bytes += size;
                        if (++lte->out_refcnt == 1)
                                *stats->hard_link_bytes += size;
                }
                if (i == dentry->num_ads)
                        break;
                lte = __lookup_resource(stats->lookup_table,
                                        dentry->ads_entries[i].hash);
                i++;
        }

        return 0;
}

void calculate_dir_tree_statistics(struct dentry *root, struct lookup_table *table, 
                                   u64 *dir_count_ret, u64 *file_count_ret, 
                                   u64 *total_bytes_ret, 
                                   u64 *hard_link_bytes_ret)
{
        struct image_statistics stats;
        *dir_count_ret         = 0;
        *file_count_ret        = 0;
        *total_bytes_ret       = 0;
        *hard_link_bytes_ret   = 0;
        stats.lookup_table     = table;
        stats.dir_count       = dir_count_ret;
        stats.file_count      = file_count_ret;
        stats.total_bytes     = total_bytes_ret;
        stats.hard_link_bytes = hard_link_bytes_ret;
        for_lookup_table_entry(table, zero_out_refcnts, NULL);
        for_dentry_in_tree(root, calculate_dentry_statistics, &stats);
}

static int read_ads_entries(const u8 *p, struct dentry *dentry,
                            u64 remaining_size)
{
        u16 num_ads = dentry->num_ads;
        struct ads_entry *ads_entries = CALLOC(num_ads, sizeof(struct ads_entry));
        int ret;
        if (!ads_entries) {
                ERROR("Could not allocate memory for %"PRIu16" "
                      "alternate data stream entries", num_ads);
                return WIMLIB_ERR_NOMEM;
        }
        DEBUG2("Reading %"PRIu16" alternate data streams "
               "(remaining size = %"PRIu64")", num_ads, remaining_size);

        for (u16 i = 0; i < num_ads; i++) {
                struct ads_entry *cur_entry = &ads_entries[i];
                u64 length;
                size_t utf8_len;
                const char *p_save = p;
                /* Read the base stream entry, excluding the stream name. */
                if (remaining_size < WIM_ADS_ENTRY_DISK_SIZE) {
                        ERROR("Stream entries go past end of metadata resource");
                        ERROR("(remaining_size = %"PRIu64")", remaining_size);
                        ret = WIMLIB_ERR_INVALID_DENTRY;
                        goto out_free_ads_entries;
                }
                remaining_size -= WIM_ADS_ENTRY_DISK_SIZE;

                p = get_u64(p, &length); /* ADS entry length */

                DEBUG2("ADS length = %"PRIu64, length);

                p += 8; /* Unused */
                p = get_bytes(p, WIM_HASH_SIZE, (u8*)cur_entry->hash);
                p = get_u16(p, &cur_entry->stream_name_len);

                DEBUG2("Stream name length = %u", cur_entry->stream_name_len);

                cur_entry->stream_name = NULL;
                cur_entry->stream_name_utf8 = NULL;

                if (remaining_size < cur_entry->stream_name_len + 2) {
                        ERROR("Stream entries go past end of metadata resource");
                        ERROR("(remaining_size = %"PRIu64" bytes, stream_name_len "
                              "= %"PRIu16" bytes", remaining_size,
                              cur_entry->stream_name_len);
                        ret = WIMLIB_ERR_INVALID_DENTRY;
                        goto out_free_ads_entries;
                }
                remaining_size -= cur_entry->stream_name_len + 2;

                cur_entry->stream_name = MALLOC(cur_entry->stream_name_len);
                if (!cur_entry->stream_name) {
                        ret = WIMLIB_ERR_NOMEM;
                        goto out_free_ads_entries;
                }
                get_bytes(p, cur_entry->stream_name_len,
                          (u8*)cur_entry->stream_name);
                cur_entry->stream_name_utf8 = utf16_to_utf8(cur_entry->stream_name,
                                                            cur_entry->stream_name_len,
                                                            &utf8_len);
                cur_entry->stream_name_utf8_len = utf8_len;

                if (!cur_entry->stream_name_utf8) {
                        ret = WIMLIB_ERR_NOMEM;
                        goto out_free_ads_entries;
                }
                p = p_save + ads_entry_length(cur_entry);
        }
        dentry->ads_entries = ads_entries;
        return 0;
out_free_ads_entries:
        for (u16 i = 0; i < num_ads; i++) {
                FREE(ads_entries[i].stream_name);
                FREE(ads_entries[i].stream_name_utf8);
        }
        FREE(ads_entries);
        return ret;
}

/* 
 * Reads a directory entry from the metadata resource.
 */
int read_dentry(const u8 metadata_resource[], u64 metadata_resource_len, 
                u64 offset, struct dentry *dentry)
{
        const u8 *p;
        u64 calculated_size;
        char *file_name;
        char *file_name_utf8;
        char *short_name;
        u16 short_name_len;
        u16 file_name_len;
        size_t file_name_utf8_len;
        int ret;

        dentry_common_init(dentry);

        /*Make sure the dentry really fits into the metadata resource.*/
        if (offset + 8 > metadata_resource_len) {
                ERROR("Directory entry starting at %"PRIu64" ends past the "
                      "end of the metadata resource (size %"PRIu64")",
                      offset, metadata_resource_len);
                return WIMLIB_ERR_INVALID_DENTRY;
        }

        /* Before reading the whole entry, we need to read just the length.
         * This is because an entry of length 8 (that is, just the length field)
         * terminates the list of sibling directory entries. */

        p = get_u64(&metadata_resource[offset], &dentry->length);

        /* A zero length field (really a length of 8, since that's how big the
         * directory entry is...) indicates that this is the end of directory
         * dentry.  We do not read it into memory as an actual dentry, so just
         * return true in that case. */
        if (dentry->length == 0)
                return 0;

        if (offset + dentry->length >= metadata_resource_len) {
                ERROR("Directory entry at offset %"PRIu64" and with size "
                      "%"PRIu64" ends past the end of the metadata resource "
                      "(size %"PRIu64")",
                      offset, dentry->length, metadata_resource_len);
                return WIMLIB_ERR_INVALID_DENTRY;
        }

        /* If it is a recognized length, read the rest of the directory entry.
         * Note: The root directory entry has no name, and its length does not
         * include the short name length field.  */
        if (dentry->length < WIM_DENTRY_DISK_SIZE) {
                ERROR("Directory entry has invalid length of %"PRIu64" bytes",
                      dentry->length);
                return WIMLIB_ERR_INVALID_DENTRY;
        }

        p = get_u32(p, &dentry->attributes);
        p = get_u32(p, (u32*)&dentry->security_id);
        p = get_u64(p, &dentry->subdir_offset);

        /* 2 unused fields */
        p += 2 * sizeof(u64);
        /*p = get_u64(p, &dentry->unused1);*/
        /*p = get_u64(p, &dentry->unused2);*/

        p = get_u64(p, &dentry->creation_time);
        p = get_u64(p, &dentry->last_access_time);
        p = get_u64(p, &dentry->last_write_time);

        p = get_bytes(p, WIM_HASH_SIZE, dentry->hash);
        
        /*
         * I don't know what's going on here.  It seems like M$ screwed up the
         * reparse points, then put the fields in the same place and didn't
         * document it.  The WIM_HDR_FLAG_RP_FIX flag in the WIM header might
         * have something to do with this, but it's not documented.
         */
        if (dentry->attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
                /* ??? */
                p += 4;
                p = get_u32(p, &dentry->reparse_tag);
                p += 4;
        } else {
                p = get_u32(p, &dentry->reparse_tag);
                p = get_u64(p, &dentry->hard_link);
        }

        /* By the way, the reparse_reserved field does not actually exist (at
         * least when the file is not a reparse point) */

        
        p = get_u16(p, &dentry->num_ads);

        p = get_u16(p, &short_name_len);
        p = get_u16(p, &file_name_len);

        calculated_size = WIM_DENTRY_DISK_SIZE + file_name_len + 2 +
                          short_name_len;

        if (dentry->length < calculated_size) {
                ERROR("Unexpected end of directory entry! (Expected "
                      "%"PRIu64" bytes, got %"PRIu64" bytes. "
                      "short_name_len = %hu, file_name_len = %hu)", 
                      calculated_size, dentry->length,
                      short_name_len, file_name_len);
                return WIMLIB_ERR_INVALID_DENTRY;
        }

        /* Read the filename. */
        file_name = MALLOC(file_name_len);
        if (!file_name) {
                ERROR("Failed to allocate %hu bytes for dentry file name",
                      file_name_len);
                return WIMLIB_ERR_NOMEM;
        }
        p = get_bytes(p, file_name_len, file_name);

        /* Convert filename to UTF-8. */
        file_name_utf8 = utf16_to_utf8(file_name, file_name_len, 
                                       &file_name_utf8_len);

        if (!file_name_utf8) {
                ERROR("Failed to allocate memory to convert UTF-16 "
                      "filename (%hu bytes) to UTF-8", file_name_len);
                ret = WIMLIB_ERR_NOMEM;
                goto out_free_file_name;
        }

        /* Undocumented padding between file name and short name.  This probably
         * is supposed to be a terminating null character. */
        p += 2;

        /* Read the short filename. */
        short_name = MALLOC(short_name_len);
        if (!short_name) {
                ERROR("Failed to allocate %hu bytes for short filename",
                      short_name_len);
                ret = WIMLIB_ERR_NOMEM;
                goto out_free_file_name_utf8;
        }

        p = get_bytes(p, short_name_len, short_name);

        /* Some directory entries inexplicibly have a little over 70 bytes of
         * extra data.  The exact amount of data seems to be 72 bytes, but it is
         * aligned on the next 8-byte boundary.  Here's an example of the
         * aligned data:
         *
         * 01000000400000006c786bbac58ede11b0bb00261870892ab6adb76fe63a3
         * e468fca86530d2effa16c786bbac58ede11b0bb00261870892a0000000000
         * 0000000000000000000000
         *
         * Here's one interpretation of how the data is laid out.
         *
         * struct unknown {
         *      u32 field1; (always 0x00000001)
         *      u32 field2; (always 0x40000000)
         *      u16 field3;
         *      u32 field4;
         *      u32 field5;
         *      u32 field6;
         *      u8  data[48]; (???)
         *      u64 reserved1; (always 0)
         *      u64 reserved2; (always 0)
         * };*/
#if 0
        if (dentry->length - calculated_size >= WIM_ADS_ENTRY_DISK_SIZE) {
                printf("%s: %lu / %lu (", file_name_utf8, 
                                calculated_size, dentry->length);
                print_string(p + WIM_ADS_ENTRY_DISK_SIZE, dentry->length - calculated_size - WIM_ADS_ENTRY_DISK_SIZE);
                puts(")");
                print_byte_field(p, dentry->length - calculated_size);
                putchar('\n');
        }
#endif

        if (dentry->num_ads != 0) {
                calculated_size = (calculated_size + 7) & ~7;
                if (calculated_size > metadata_resource_len - offset) {
                        ERROR("Not enough space in metadata resource for "
                              "alternate stream entries");
                        ret = WIMLIB_ERR_INVALID_DENTRY;
                        goto out_free_short_name;
                }
                ret = read_ads_entries(&metadata_resource[offset + calculated_size],
                                       dentry,
                                       metadata_resource_len - offset - calculated_size);
                if (ret != 0)
                        goto out_free_short_name;
        }

        dentry->file_name          = file_name;
        dentry->file_name_utf8     = file_name_utf8;
        dentry->short_name         = short_name;
        dentry->file_name_len      = file_name_len;
        dentry->file_name_utf8_len = file_name_utf8_len;
        dentry->short_name_len     = short_name_len;
        return 0;
out_free_short_name:
        FREE(short_name);
out_free_file_name_utf8:
        FREE(file_name_utf8);
out_free_file_name:
        FREE(file_name);
        return ret;
}

/* 
 * Writes a dentry to an output buffer.
 *
 * @dentry:  The dentry structure.
 * @p:       The memory location to write the data to.
 * @return:  Pointer to the byte after the last byte we wrote as part of the
 *              dentry.
 */
static u8 *write_dentry(const struct dentry *dentry, u8 *p)
{
        u8 *orig_p = p;
        unsigned padding;

        p = put_u64(p, dentry->length);
        p = put_u32(p, dentry->attributes);
        p = put_u32(p, dentry->security_id);
        p = put_u64(p, dentry->subdir_offset);
        p = put_u64(p, 0); /* unused1 */
        p = put_u64(p, 0); /* unused2 */
        p = put_u64(p, dentry->creation_time);
        p = put_u64(p, dentry->last_access_time);
        p = put_u64(p, dentry->last_write_time);
        p = put_bytes(p, WIM_HASH_SIZE, dentry->hash);
        if (dentry->attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
                p = put_zeroes(p, 4);
                p = put_u32(p, dentry->reparse_tag);
                p = put_zeroes(p, 4);
        } else {
                p = put_u32(p, dentry->reparse_tag);
                p = put_u64(p, dentry->hard_link);
        }
        p = put_u16(p, dentry->num_ads);
        p = put_u16(p, dentry->short_name_len);
        p = put_u16(p, dentry->file_name_len);
        p = put_bytes(p, dentry->file_name_len, (u8*)dentry->file_name);
        p = put_u16(p, 0); /* filename padding, 2 bytes. */
        p = put_bytes(p, dentry->short_name_len, (u8*)dentry->short_name);

        wimlib_assert(p - orig_p <= dentry->length);
        if (p - orig_p < dentry->length)
                p = put_zeroes(p, dentry->length - (p - orig_p));

        p = put_zeroes(p, (8 - (p - orig_p) % 8) % 8);

        for (u16 i = 0; i < dentry->num_ads; i++) {
                p = put_u64(p, ads_entry_length(&dentry->ads_entries[i]));
                p = put_u64(p, 0); /* Unused */
                p = put_bytes(p, WIM_HASH_SIZE, dentry->ads_entries[i].hash);
                p = put_u16(p, dentry->ads_entries[i].stream_name_len);
                p = put_bytes(p, dentry->ads_entries[i].stream_name_len,
                                 (u8*)dentry->ads_entries[i].stream_name);
                p = put_zeroes(p, (8 - (p - orig_p) % 8) % 8);
        }
        return p;
}

/* Recursive function that writes a dentry tree rooted at @tree, not including
 * @tree itself, which has already been written, except in the case of the root
 * dentry, which is written right away, along with an end-of-directory entry. */
u8 *write_dentry_tree(const struct dentry *tree, u8 *p)
{
        const struct dentry *child;

        if (dentry_is_root(tree)) {
                p = write_dentry(tree, p);

                /* write end of directory entry */
                p = put_u64(p, 0);
        } else {
                /* Nothing to do for non-directories */
                if (!dentry_is_directory(tree))
                        return p;
        }

        /* Write child dentries and end-of-directory entry. */
        child = tree->children;
        if (child) {
                do {
                        p = write_dentry(child, p);
                        child = child->next;
                } while (child != tree->children);
        }

        /* write end of directory entry */
        p = put_u64(p, 0);

        /* Recurse on children. */
        if (child) {
                do {
                        p = write_dentry_tree(child, p);
                        child = child->next;
                } while (child != tree->children);
        }
        return p;
}

/* Reads the children of a dentry, and all their children, ..., etc. from the
 * metadata resource and into the dentry tree.
 *
 * @metadata_resource:  An array that contains the uncompressed metadata
 *                      resource for the WIM file.
 * @metadata_resource_len:      The length of @metadata_resource.
 * @dentry:     A pointer to a struct dentry that is the root of the directory
 *              tree and has already been read from the metadata resource.  It
 *              does not need to be the real root because this procedure is
 *              called recursively.
 *
 * @return:     Zero on success, nonzero on failure.
 */
int read_dentry_tree(const u8 metadata_resource[], u64 metadata_resource_len,
                     struct dentry *dentry)
{
        u64 cur_offset = dentry->subdir_offset;
        struct dentry *prev_child = NULL;
        struct dentry *first_child = NULL;
        struct dentry *child;
        struct dentry cur_child;
        int ret;

        /* If @dentry is a regular file, nothing more needs to be done for this
         * branch. */
        if (cur_offset == 0)
                return 0;

        /* Find and read all the children of @dentry. */
        while (1) {

                /* Read next child of @dentry into @cur_child. */
                ret = read_dentry(metadata_resource, metadata_resource_len, 
                                  cur_offset, &cur_child);
                if (ret != 0)
                        break;

                /* Check for end of directory. */
                if (cur_child.length == 0) {
                        ret = 0;
                        break;
                }

                /* Not end of directory.  Allocate this child permanently and
                 * link it to the parent and previous child. */
                child = MALLOC(sizeof(struct dentry));
                if (!child) {
                        ERROR("Failed to allocate %zu bytes for new dentry",
                              sizeof(struct dentry));
                        ret = WIMLIB_ERR_NOMEM;
                        break;
                }
                memcpy(child, &cur_child, sizeof(struct dentry));

                if (prev_child) {
                        prev_child->next = child;
                        child->prev = prev_child;
                } else {
                        first_child = child;
                }

                child->parent = dentry;
                prev_child = child;

                /* If there are children of this child, call this procedure
                 * recursively. */
                if (child->subdir_offset != 0) {
                        ret = read_dentry_tree(metadata_resource, 
                                               metadata_resource_len, child);
                        if (ret != 0)
                                break;
                }

                /* Advance to the offset of the next child. */
                cur_offset += dentry_total_length(child);
        }

        /* Link last child to first one, and set parent's
         * children pointer to the first child.  */
        if (prev_child) {
                prev_child->next = first_child;
                first_child->prev = prev_child;
        }
        dentry->children = first_child;
        return ret;
}