read_dentry_tree(): Ignore duplicate dentries

[wimlib] / src / dentry.c

/*
 * dentry.c
 *
 * 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) 2012, 2013 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 General Public License as published by the Free Software
 * Foundation; either version 3 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * wimlib; if not, see http://www.gnu.org/licenses/.
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include "wimlib.h"
#include "wimlib/dentry.h"
#include "wimlib/encoding.h"
#include "wimlib/endianness.h"
#include "wimlib/error.h"
#include "wimlib/lookup_table.h"
#include "wimlib/metadata.h"
#include "wimlib/resource.h"
#include "wimlib/sha1.h"
#include "wimlib/timestamp.h"

#include <errno.h>

/* WIM alternate data stream entry (on-disk format) */
struct wim_ads_entry_on_disk {
        /*  Length of the entry, in bytes.  This apparently includes all
         *  fixed-length fields, plus the stream name and null terminator if
         *  present, and the padding up to an 8 byte boundary.  wimlib is a
         *  little less strict when reading the entries, and only requires that
         *  the number of bytes from this field is at least as large as the size
         *  of the fixed length fields and stream name without null terminator.
         *  */
        le64  length;

        le64  reserved;

        /* SHA1 message digest of the uncompressed stream; or, alternatively,
         * can be all zeroes if the stream has zero length. */
        u8 hash[SHA1_HASH_SIZE];

        /* Length of the stream name, in bytes.  0 if the stream is unnamed.  */
        le16 stream_name_nbytes;

        /* Stream name in UTF-16LE.  It is @stream_name_nbytes bytes long,
         * excluding the the null terminator.  There is a null terminator
         * character if @stream_name_nbytes != 0; i.e., if this stream is named.
         * */
        utf16lechar stream_name[];
} _packed_attribute;

/* WIM directory entry (on-disk format) */
struct wim_dentry_on_disk {
        le64 length;
        le32 attributes;
        sle32 security_id;
        le64 subdir_offset;
        le64 unused_1;
        le64 unused_2;
        le64 creation_time;
        le64 last_access_time;
        le64 last_write_time;
        u8 unnamed_stream_hash[SHA1_HASH_SIZE];
        union {
                struct {
                        le32 rp_unknown_1;
                        le32 reparse_tag;
                        le16 rp_unknown_2;
                        le16 not_rpfixed;
                } _packed_attribute reparse;
                struct {
                        le32 rp_unknown_1;
                        le64 hard_link_group_id;
                } _packed_attribute nonreparse;
        };
        le16 num_alternate_data_streams;
        le16 short_name_nbytes;
        le16 file_name_nbytes;

        /* Follewed by variable length file name, if file_name_nbytes != 0 */
        utf16lechar file_name[];

        /* Followed by variable length short name, if short_name_nbytes != 0 */
        /*utf16lechar short_name[];*/
} _packed_attribute;

/* Calculates the unaligned length, in bytes, of an on-disk WIM dentry that has
 * a file name and short name that take the specified numbers of bytes.  This
 * excludes any alternate data stream entries that may follow the dentry. */
static u64
_dentry_correct_length_unaligned(u16 file_name_nbytes, u16 short_name_nbytes)
{
        u64 length = sizeof(struct wim_dentry_on_disk);
        if (file_name_nbytes)
                length += file_name_nbytes + 2;
        if (short_name_nbytes)
                length += short_name_nbytes + 2;
        return length;
}

/* Calculates the unaligned length, in bytes, of an on-disk WIM dentry, based on
 * the file name length and short name length.  Note that dentry->length is
 * ignored; also, this excludes any alternate data stream entries that may
 * follow the dentry. */
static u64
dentry_correct_length_unaligned(const struct wim_dentry *dentry)
{
        return _dentry_correct_length_unaligned(dentry->file_name_nbytes,
                                                dentry->short_name_nbytes);
}

/* Return %true iff the alternate data stream entry @entry has the UTF-16LE
 * stream name @name that has length @name_nbytes bytes. */
static inline bool
ads_entry_has_name(const struct wim_ads_entry *entry,
                   const utf16lechar *name, size_t name_nbytes)
{
        return entry->stream_name_nbytes == name_nbytes &&
               memcmp(entry->stream_name, name, name_nbytes) == 0;
}

/* Duplicates a string of system-dependent encoding into a UTF-16LE string and
 * returns the string and its length, in bytes, in the pointer arguments.  Frees
 * any existing string at the return location before overwriting it. */
static int
get_utf16le_name(const tchar *name, utf16lechar **name_utf16le_ret,
                 u16 *name_utf16le_nbytes_ret)
{
        utf16lechar *name_utf16le;
        size_t name_utf16le_nbytes;
        int ret;
#if TCHAR_IS_UTF16LE
        name_utf16le_nbytes = tstrlen(name) * sizeof(utf16lechar);
        name_utf16le = MALLOC(name_utf16le_nbytes + sizeof(utf16lechar));
        if (!name_utf16le)
                return WIMLIB_ERR_NOMEM;
        memcpy(name_utf16le, name, name_utf16le_nbytes + sizeof(utf16lechar));
        ret = 0;
#else

        ret = tstr_to_utf16le(name, tstrlen(name), &name_utf16le,
                              &name_utf16le_nbytes);
        if (ret == 0) {
                if (name_utf16le_nbytes > 0xffff) {
                        FREE(name_utf16le);
                        ERROR("Multibyte string \"%"TS"\" is too long!", name);
                        ret = WIMLIB_ERR_INVALID_UTF8_STRING;
                }
        }
#endif
        if (ret == 0) {
                FREE(*name_utf16le_ret);
                *name_utf16le_ret = name_utf16le;
                *name_utf16le_nbytes_ret = name_utf16le_nbytes;
        }
        return ret;
}

/* Sets the name of a WIM dentry from a multibyte string. */
int
set_dentry_name(struct wim_dentry *dentry, const tchar *new_name)
{
        int ret;
        ret = get_utf16le_name(new_name, &dentry->file_name,
                               &dentry->file_name_nbytes);
        if (ret == 0) {
                /* Clear the short name and recalculate the dentry length */
                if (dentry_has_short_name(dentry)) {
                        FREE(dentry->short_name);
                        dentry->short_name = NULL;
                        dentry->short_name_nbytes = 0;
                }
        }
        return ret;
}

/* Returns the total length of a WIM alternate data stream entry on-disk,
 * including the stream name, the null terminator, AND the padding after the
 * entry to align the next ADS entry or dentry on an 8-byte boundary. */
static u64
ads_entry_total_length(const struct wim_ads_entry *entry)
{
        u64 len = sizeof(struct wim_ads_entry_on_disk);
        if (entry->stream_name_nbytes)
                len += entry->stream_name_nbytes + 2;
        return (len + 7) & ~7;
}


static u64
_dentry_total_length(const struct wim_dentry *dentry, u64 length)
{
        const struct wim_inode *inode = dentry->d_inode;
        for (u16 i = 0; i < inode->i_num_ads; i++)
                length += ads_entry_total_length(&inode->i_ads_entries[i]);
        return (length + 7) & ~7;
}

/* Calculate the aligned *total* length of an on-disk WIM dentry.  This includes
 * all alternate data streams. */
u64
dentry_correct_total_length(const struct wim_dentry *dentry)
{
        return _dentry_total_length(dentry,
                                    dentry_correct_length_unaligned(dentry));
}

/* Like dentry_correct_total_length(), but use the existing dentry->length field
 * instead of calculating its "correct" value. */
static u64
dentry_total_length(const struct wim_dentry *dentry)
{
        return _dentry_total_length(dentry, dentry->length);
}

int
for_dentry_in_rbtree(struct rb_node *root,
                     int (*visitor)(struct wim_dentry *, void *),
                     void *arg)
{
        int ret;
        struct rb_node *node = root;
        LIST_HEAD(stack);
        while (1) {
                if (node) {
                        list_add(&rbnode_dentry(node)->tmp_list, &stack);
                        node = node->rb_left;
                } else {
                        struct list_head *next;
                        struct wim_dentry *dentry;

                        next = stack.next;
                        if (next == &stack)
                                return 0;
                        dentry = container_of(next, struct wim_dentry, tmp_list);
                        list_del(next);
                        ret = visitor(dentry, arg);
                        if (ret != 0)
                                return ret;
                        node = dentry->rb_node.rb_right;
                }
        }
}

static int
for_dentry_tree_in_rbtree_depth(struct rb_node *node,
                                int (*visitor)(struct wim_dentry*, void*),
                                void *arg)
{
        int ret;
        if (node) {
                ret = for_dentry_tree_in_rbtree_depth(node->rb_left,
                                                      visitor, arg);
                if (ret != 0)
                        return ret;
                ret = for_dentry_tree_in_rbtree_depth(node->rb_right,
                                                      visitor, arg);
                if (ret != 0)
                        return ret;
                ret = for_dentry_in_tree_depth(rbnode_dentry(node), visitor, arg);
                if (ret != 0)
                        return ret;
        }
        return 0;
}

static int
for_dentry_tree_in_rbtree(struct rb_node *node,
                          int (*visitor)(struct wim_dentry*, void*),
                          void *arg)
{
        int ret;
        if (node) {
                ret = for_dentry_tree_in_rbtree(node->rb_left, visitor, arg);
                if (ret)
                        return ret;
                ret = for_dentry_in_tree(rbnode_dentry(node), visitor, arg);
                if (ret)
                        return ret;
                ret = for_dentry_tree_in_rbtree(node->rb_right, visitor, arg);
                if (ret)
                        return ret;
        }
        return 0;
}

/* Calls a function on all directory entries in a WIM dentry tree.  Logically,
 * this is a pre-order traversal (the function is called on a parent dentry
 * before its children), but sibling dentries will be visited in order as well.
 * */
int
for_dentry_in_tree(struct wim_dentry *root,
                   int (*visitor)(struct wim_dentry*, void*), void *arg)
{
        int ret;

        if (!root)
                return 0;
        ret = (*visitor)(root, arg);
        if (ret)
                return ret;
        return for_dentry_tree_in_rbtree(root->d_inode->i_children.rb_node,
                                         visitor,
                                         arg);
}

/* 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 wim_dentry *root,
                         int (*visitor)(struct wim_dentry*, void*), void *arg)
{
        int ret;

        if (!root)
                return 0;
        ret = for_dentry_tree_in_rbtree_depth(root->d_inode->i_children.rb_node,
                                              visitor, arg);
        if (ret)
                return ret;
        return (*visitor)(root, arg);
}

/* Calculate the full path of @dentry.  The full path of its parent must have
 * already been calculated, or it must be the root dentry. */
static int
calculate_dentry_full_path(struct wim_dentry *dentry)
{
        tchar *full_path;
        u32 full_path_nbytes;
        int ret;

        if (dentry->_full_path)
                return 0;

        if (dentry_is_root(dentry)) {
                full_path = TSTRDUP(T("/"));
                if (!full_path)
                        return WIMLIB_ERR_NOMEM;
                full_path_nbytes = 1 * sizeof(tchar);
        } else {
                struct wim_dentry *parent;
                tchar *parent_full_path;
                u32 parent_full_path_nbytes;
                size_t filename_nbytes;

                parent = dentry->parent;
                if (dentry_is_root(parent)) {
                        parent_full_path = T("");
                        parent_full_path_nbytes = 0;
                } else {
                        if (!parent->_full_path) {
                                ret = calculate_dentry_full_path(parent);
                                if (ret)
                                        return ret;
                        }
                        parent_full_path = parent->_full_path;
                        parent_full_path_nbytes = parent->full_path_nbytes;
                }

                /* Append this dentry's name as a tchar string to the full path
                 * of the parent followed by the path separator */
        #if TCHAR_IS_UTF16LE
                filename_nbytes = dentry->file_name_nbytes;
        #else
                {
                        int ret = utf16le_to_tstr_nbytes(dentry->file_name,
                                                         dentry->file_name_nbytes,
                                                         &filename_nbytes);
                        if (ret)
                                return ret;
                }
        #endif

                full_path_nbytes = parent_full_path_nbytes + sizeof(tchar) +
                                   filename_nbytes;
                full_path = MALLOC(full_path_nbytes + sizeof(tchar));
                if (!full_path)
                        return WIMLIB_ERR_NOMEM;
                memcpy(full_path, parent_full_path, parent_full_path_nbytes);
                full_path[parent_full_path_nbytes / sizeof(tchar)] = T('/');
        #if TCHAR_IS_UTF16LE
                memcpy(&full_path[parent_full_path_nbytes / sizeof(tchar) + 1],
                       dentry->file_name,
                       filename_nbytes + sizeof(tchar));
        #else
                utf16le_to_tstr_buf(dentry->file_name,
                                    dentry->file_name_nbytes,
                                    &full_path[parent_full_path_nbytes /
                                               sizeof(tchar) + 1]);
        #endif
        }
        dentry->_full_path = full_path;
        dentry->full_path_nbytes= full_path_nbytes;
        return 0;
}

static int
do_calculate_dentry_full_path(struct wim_dentry *dentry, void *_ignore)
{
        return calculate_dentry_full_path(dentry);
}

int
calculate_dentry_tree_full_paths(struct wim_dentry *root)
{
        return for_dentry_in_tree(root, do_calculate_dentry_full_path, NULL);
}

tchar *
dentry_full_path(struct wim_dentry *dentry)
{
        calculate_dentry_full_path(dentry);
        return dentry->_full_path;
}

static int
increment_subdir_offset(struct wim_dentry *dentry, void *subdir_offset_p)
{
        *(u64*)subdir_offset_p += dentry_correct_total_length(dentry);
        return 0;
}

static int
call_calculate_subdir_offsets(struct wim_dentry *dentry, void *subdir_offset_p)
{
        calculate_subdir_offsets(dentry, subdir_offset_p);
        return 0;
}

/*
 * 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 wim_dentry *dentry, u64 *subdir_offset_p)
{
        struct rb_node *node;

        dentry->subdir_offset = *subdir_offset_p;
        node = dentry->d_inode->i_children.rb_node;
        if (node) {
                /* Advance the subdir offset by the amount of space the children
                 * of this dentry take up. */
                for_dentry_in_rbtree(node, increment_subdir_offset, subdir_offset_p);

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

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

static int
compare_utf16le_names(const utf16lechar *name1, size_t nbytes1,
                      const utf16lechar *name2, size_t nbytes2)
{
        int result = memcmp(name1, name2, min(nbytes1, nbytes2));
        if (result)
                return result;
        else
                return (int)nbytes1 - (int)nbytes2;
}

static int
dentry_compare_names(const struct wim_dentry *d1, const struct wim_dentry *d2)
{
        return compare_utf16le_names(d1->file_name, d1->file_name_nbytes,
                                     d2->file_name, d2->file_name_nbytes);
}


struct wim_dentry *
get_dentry_child_with_utf16le_name(const struct wim_dentry *dentry,
                                   const utf16lechar *name,
                                   size_t name_nbytes)
{
        struct rb_node *node = dentry->d_inode->i_children.rb_node;
        struct wim_dentry *child;
        while (node) {
                child = rbnode_dentry(node);
                int result = compare_utf16le_names(name, name_nbytes,
                                                   child->file_name,
                                                   child->file_name_nbytes);
                if (result < 0)
                        node = node->rb_left;
                else if (result > 0)
                        node = node->rb_right;
                else
                        return child;
        }
        return NULL;
}

/* Returns the child of @dentry that has the file name @name.  Returns NULL if
 * no child has the name. */
struct wim_dentry *
get_dentry_child_with_name(const struct wim_dentry *dentry, const tchar *name)
{
#if TCHAR_IS_UTF16LE
        return get_dentry_child_with_utf16le_name(dentry, name,
                                                  tstrlen(name) * sizeof(tchar));
#else
        utf16lechar *utf16le_name;
        size_t utf16le_name_nbytes;
        int ret;
        struct wim_dentry *child;

        ret = tstr_to_utf16le(name, tstrlen(name) * sizeof(tchar),
                              &utf16le_name, &utf16le_name_nbytes);
        if (ret) {
                child = NULL;
        } else {
                child = get_dentry_child_with_utf16le_name(dentry,
                                                           utf16le_name,
                                                           utf16le_name_nbytes);
                FREE(utf16le_name);
        }
        return child;
#endif
}

static struct wim_dentry *
get_dentry_utf16le(WIMStruct *wim, const utf16lechar *path)
{
        struct wim_dentry *cur_dentry, *parent_dentry;
        const utf16lechar *p, *pp;

        cur_dentry = parent_dentry = wim_root_dentry(wim);
        if (!cur_dentry) {
                errno = ENOENT;
                return NULL;
        }
        p = path;
        while (1) {
                while (*p == cpu_to_le16('/'))
                        p++;
                if (*p == cpu_to_le16('\0'))
                        break;
                pp = p;
                while (*pp != cpu_to_le16('/') && *pp != cpu_to_le16('\0'))
                        pp++;

                cur_dentry = get_dentry_child_with_utf16le_name(parent_dentry, p,
                                                                (void*)pp - (void*)p);
                if (cur_dentry == NULL)
                        break;
                p = pp;
                parent_dentry = cur_dentry;
        }
        if (cur_dentry == NULL) {
                if (dentry_is_directory(parent_dentry))
                        errno = ENOENT;
                else
                        errno = ENOTDIR;
        }
        return cur_dentry;
}

/* Returns the dentry corresponding to the @path, or NULL if there is no such
 * dentry. */
struct wim_dentry *
get_dentry(WIMStruct *wim, const tchar *path)
{
#if TCHAR_IS_UTF16LE
        return get_dentry_utf16le(wim, path);
#else
        utf16lechar *path_utf16le;
        size_t path_utf16le_nbytes;
        int ret;
        struct wim_dentry *dentry;

        ret = tstr_to_utf16le(path, tstrlen(path) * sizeof(tchar),
                              &path_utf16le, &path_utf16le_nbytes);
        if (ret)
                return NULL;
        dentry = get_dentry_utf16le(wim, path_utf16le);
        FREE(path_utf16le);
        return dentry;
#endif
}

struct wim_inode *
wim_pathname_to_inode(WIMStruct *wim, const tchar *path)
{
        struct wim_dentry *dentry;
        dentry = get_dentry(wim, path);
        if (dentry)
                return dentry->d_inode;
        else
                return NULL;
}

/* Takes in a path of length @len in @buf, and transforms it into a string for
 * the path of its parent directory. */
static void
to_parent_name(tchar *buf, size_t len)
{
        ssize_t i = (ssize_t)len - 1;
        while (i >= 0 && buf[i] == T('/'))
                i--;
        while (i >= 0 && buf[i] != T('/'))
                i--;
        while (i >= 0 && buf[i] == T('/'))
                i--;
        buf[i + 1] = T('\0');
}

/* Returns the dentry that corresponds to the parent directory of @path, or NULL
 * if the dentry is not found. */
struct wim_dentry *
get_parent_dentry(WIMStruct *wim, const tchar *path)
{
        size_t path_len = tstrlen(path);
        tchar buf[path_len + 1];

        tmemcpy(buf, path, path_len + 1);
        to_parent_name(buf, path_len);
        return get_dentry(wim, buf);
}

/* Prints the full path of a dentry. */
int
print_dentry_full_path(struct wim_dentry *dentry, void *_ignore)
{
        int ret = calculate_dentry_full_path(dentry);
        if (ret)
                return ret;
        tprintf(T("%"TS"\n"), dentry->_full_path);
        return 0;
}

/* We want to be able to show the names of the file attribute flags that are
 * set. */
struct file_attr_flag {
        u32 flag;
        const tchar *name;
};
struct file_attr_flag file_attr_flags[] = {
        {FILE_ATTRIBUTE_READONLY,           T("READONLY")},
        {FILE_ATTRIBUTE_HIDDEN,             T("HIDDEN")},
        {FILE_ATTRIBUTE_SYSTEM,             T("SYSTEM")},
        {FILE_ATTRIBUTE_DIRECTORY,          T("DIRECTORY")},
        {FILE_ATTRIBUTE_ARCHIVE,            T("ARCHIVE")},
        {FILE_ATTRIBUTE_DEVICE,             T("DEVICE")},
        {FILE_ATTRIBUTE_NORMAL,             T("NORMAL")},
        {FILE_ATTRIBUTE_TEMPORARY,          T("TEMPORARY")},
        {FILE_ATTRIBUTE_SPARSE_FILE,        T("SPARSE_FILE")},
        {FILE_ATTRIBUTE_REPARSE_POINT,      T("REPARSE_POINT")},
        {FILE_ATTRIBUTE_COMPRESSED,         T("COMPRESSED")},
        {FILE_ATTRIBUTE_OFFLINE,            T("OFFLINE")},
        {FILE_ATTRIBUTE_NOT_CONTENT_INDEXED,T("NOT_CONTENT_INDEXED")},
        {FILE_ATTRIBUTE_ENCRYPTED,          T("ENCRYPTED")},
        {FILE_ATTRIBUTE_VIRTUAL,            T("VIRTUAL")},
};

/* Prints a directory entry.  @lookup_table is a pointer to the lookup table, if
 * available.  If the dentry is unresolved and the lookup table is NULL, the
 * lookup table entries will not be printed.  Otherwise, they will be. */
int
print_dentry(struct wim_dentry *dentry, void *lookup_table)
{
        const u8 *hash;
        struct wim_lookup_table_entry *lte;
        const struct wim_inode *inode = dentry->d_inode;
        tchar buf[50];

        tprintf(T("[DENTRY]\n"));
        tprintf(T("Length            = %"PRIu64"\n"), dentry->length);
        tprintf(T("Attributes        = 0x%x\n"), inode->i_attributes);
        for (size_t i = 0; i < ARRAY_LEN(file_attr_flags); i++)
                if (file_attr_flags[i].flag & inode->i_attributes)
                        tprintf(T("    FILE_ATTRIBUTE_%"TS" is set\n"),
                                file_attr_flags[i].name);
        tprintf(T("Security ID       = %d\n"), inode->i_security_id);
        tprintf(T("Subdir offset     = %"PRIu64"\n"), dentry->subdir_offset);

        wim_timestamp_to_str(inode->i_creation_time, buf, sizeof(buf));
        tprintf(T("Creation Time     = %"TS"\n"), buf);

        wim_timestamp_to_str(inode->i_last_access_time, buf, sizeof(buf));
        tprintf(T("Last Access Time  = %"TS"\n"), buf);

        wim_timestamp_to_str(inode->i_last_write_time, buf, sizeof(buf));
        tprintf(T("Last Write Time   = %"TS"\n"), buf);

        if (inode->i_attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
                tprintf(T("Reparse Tag       = 0x%"PRIx32"\n"), inode->i_reparse_tag);
                tprintf(T("Reparse Point Flags = 0x%"PRIx16"\n"),
                        inode->i_not_rpfixed);
                tprintf(T("Reparse Point Unknown 2 = 0x%"PRIx32"\n"),
                        inode->i_rp_unknown_2);
        }
        tprintf(T("Reparse Point Unknown 1 = 0x%"PRIx32"\n"),
                inode->i_rp_unknown_1);
        tprintf(T("Hard Link Group   = 0x%"PRIx64"\n"), inode->i_ino);
        tprintf(T("Hard Link Group Size = %"PRIu32"\n"), inode->i_nlink);
        tprintf(T("Number of Alternate Data Streams = %hu\n"), inode->i_num_ads);
        if (dentry_has_long_name(dentry))
                wimlib_printf(T("Filename = \"%"WS"\"\n"), dentry->file_name);
        if (dentry_has_short_name(dentry))
                wimlib_printf(T("Short Name \"%"WS"\"\n"), dentry->short_name);
        if (dentry->_full_path)
                tprintf(T("Full Path = \"%"TS"\"\n"), dentry->_full_path);

        lte = inode_stream_lte(dentry->d_inode, 0, lookup_table);
        if (lte) {
                print_lookup_table_entry(lte, stdout);
        } else {
                hash = inode_stream_hash(inode, 0);
                if (hash) {
                        tprintf(T("Hash              = 0x"));
                        print_hash(hash, stdout);
                        tputchar(T('\n'));
                        tputchar(T('\n'));
                }
        }
        for (u16 i = 0; i < inode->i_num_ads; i++) {
                tprintf(T("[Alternate Stream Entry %u]\n"), i);
                wimlib_printf(T("Name = \"%"WS"\"\n"),
                              inode->i_ads_entries[i].stream_name);
                tprintf(T("Name Length (UTF16 bytes) = %hu\n"),
                       inode->i_ads_entries[i].stream_name_nbytes);
                hash = inode_stream_hash(inode, i + 1);
                if (hash) {
                        tprintf(T("Hash              = 0x"));
                        print_hash(hash, stdout);
                        tputchar(T('\n'));
                }
                print_lookup_table_entry(inode_stream_lte(inode, i + 1, lookup_table),
                                         stdout);
        }
        return 0;
}

/* Initializations done on every `struct wim_dentry'. */
static void
dentry_common_init(struct wim_dentry *dentry)
{
        memset(dentry, 0, sizeof(struct wim_dentry));
}

struct wim_inode *
new_timeless_inode(void)
{
        struct wim_inode *inode = CALLOC(1, sizeof(struct wim_inode));
        if (inode) {
                inode->i_security_id = -1;
                inode->i_nlink = 1;
                inode->i_next_stream_id = 1;
                inode->i_not_rpfixed = 1;
                INIT_LIST_HEAD(&inode->i_list);
        #ifdef WITH_FUSE
                if (pthread_mutex_init(&inode->i_mutex, NULL) != 0) {
                        ERROR_WITH_ERRNO("Error initializing mutex");
                        FREE(inode);
                        return NULL;
                }
        #endif
                INIT_LIST_HEAD(&inode->i_dentry);
        }
        return inode;
}

static struct wim_inode *
new_inode(void)
{
        struct wim_inode *inode = new_timeless_inode();
        if (inode) {
                u64 now = get_wim_timestamp();
                inode->i_creation_time = now;
                inode->i_last_access_time = now;
                inode->i_last_write_time = now;
        }
        return inode;
}

/* Creates an unlinked directory entry. */
int
new_dentry(const tchar *name, struct wim_dentry **dentry_ret)
{
        struct wim_dentry *dentry;
        int ret;

        dentry = MALLOC(sizeof(struct wim_dentry));
        if (!dentry)
                return WIMLIB_ERR_NOMEM;

        dentry_common_init(dentry);
        ret = set_dentry_name(dentry, name);
        if (ret == 0) {
                dentry->parent = dentry;
                *dentry_ret = dentry;
        } else {
                FREE(dentry);
                ERROR("Failed to set name on new dentry with name \"%"TS"\"",
                      name);
        }
        return ret;
}


static int
_new_dentry_with_inode(const tchar *name, struct wim_dentry **dentry_ret,
                        bool timeless)
{
        struct wim_dentry *dentry;
        int ret;

        ret = new_dentry(name, &dentry);
        if (ret)
                return ret;

        if (timeless)
                dentry->d_inode = new_timeless_inode();
        else
                dentry->d_inode = new_inode();
        if (!dentry->d_inode) {
                free_dentry(dentry);
                return WIMLIB_ERR_NOMEM;
        }

        inode_add_dentry(dentry, dentry->d_inode);
        *dentry_ret = dentry;
        return 0;
}

int
new_dentry_with_timeless_inode(const tchar *name, struct wim_dentry **dentry_ret)
{
        return _new_dentry_with_inode(name, dentry_ret, true);
}

int
new_dentry_with_inode(const tchar *name, struct wim_dentry **dentry_ret)
{
        return _new_dentry_with_inode(name, dentry_ret, false);
}

int
new_filler_directory(const tchar *name, struct wim_dentry **dentry_ret)
{
        int ret;
        struct wim_dentry *dentry;

        DEBUG("Creating filler directory \"%"TS"\"", name);
        ret = new_dentry_with_inode(name, &dentry);
        if (ret)
                return ret;
        /* Leave the inode number as 0; this is allowed for non
         * hard-linked files. */
        dentry->d_inode->i_resolved = 1;
        dentry->d_inode->i_attributes = FILE_ATTRIBUTE_DIRECTORY;
        *dentry_ret = dentry;
        return 0;
}

static int
init_ads_entry(struct wim_ads_entry *ads_entry, const void *name,
               size_t name_nbytes, bool is_utf16le)
{
        int ret = 0;
        memset(ads_entry, 0, sizeof(*ads_entry));

        if (is_utf16le) {
                utf16lechar *p = MALLOC(name_nbytes + sizeof(utf16lechar));
                if (!p)
                        return WIMLIB_ERR_NOMEM;
                memcpy(p, name, name_nbytes);
                p[name_nbytes / 2] = cpu_to_le16(0);
                ads_entry->stream_name = p;
                ads_entry->stream_name_nbytes = name_nbytes;
        } else {
                if (name && *(const tchar*)name != T('\0')) {
                        ret = get_utf16le_name(name, &ads_entry->stream_name,
                                               &ads_entry->stream_name_nbytes);
                }
        }
        return ret;
}

static void
destroy_ads_entry(struct wim_ads_entry *ads_entry)
{
        FREE(ads_entry->stream_name);
}

/* Frees an inode. */
void
free_inode(struct wim_inode *inode)
{
        if (inode) {
                if (inode->i_ads_entries) {
                        for (u16 i = 0; i < inode->i_num_ads; i++)
                                destroy_ads_entry(&inode->i_ads_entries[i]);
                        FREE(inode->i_ads_entries);
                }
        #ifdef WITH_FUSE
                wimlib_assert(inode->i_num_opened_fds == 0);
                FREE(inode->i_fds);
                pthread_mutex_destroy(&inode->i_mutex);
        #endif
                /* HACK: This may instead delete the inode from i_list, but the
                 * hlist_del() behaves the same as list_del(). */
                hlist_del(&inode->i_hlist);
                FREE(inode->i_extracted_file);
                FREE(inode);
        }
}

/* Decrements link count on an inode and frees it if the link count reaches 0.
 * */
static void
put_inode(struct wim_inode *inode)
{
        wimlib_assert(inode->i_nlink != 0);
        if (--inode->i_nlink == 0) {
        #ifdef WITH_FUSE
                if (inode->i_num_opened_fds == 0)
        #endif
                {
                        free_inode(inode);
                }
        }
}

/* Frees a WIM dentry.
 *
 * The corresponding inode (if any) is freed only if its link count is
 * decremented to 0.
 */
void
free_dentry(struct wim_dentry *dentry)
{
        if (dentry) {
                FREE(dentry->file_name);
                FREE(dentry->short_name);
                FREE(dentry->_full_path);
                if (dentry->d_inode)
                        put_inode(dentry->d_inode);
                FREE(dentry);
        }
}

/* This function is passed as an argument to for_dentry_in_tree_depth() in order
 * to free a directory tree. */
static int
do_free_dentry(struct wim_dentry *dentry, void *_lookup_table)
{
        struct wim_lookup_table *lookup_table = _lookup_table;

        if (lookup_table) {
                struct wim_inode *inode = dentry->d_inode;
                for (unsigned i = 0; i <= inode->i_num_ads; i++) {
                        struct wim_lookup_table_entry *lte;

                        lte = inode_stream_lte(inode, i, lookup_table);
                        if (lte)
                                lte_decrement_refcnt(lte, lookup_table);
                }
        }
        free_dentry(dentry);
        return 0;
}

/*
 * Unlinks and frees a dentry tree.
 *
 * @root:               The root of the tree.
 * @lookup_table:       The lookup table for dentries.  If non-NULL, the
 *                      reference counts in the lookup table for the lookup
 *                      table entries corresponding to the dentries will be
 *                      decremented.
 */
void
free_dentry_tree(struct wim_dentry *root, struct wim_lookup_table *lookup_table)
{
        for_dentry_in_tree_depth(root, do_free_dentry, lookup_table);
}

/*
 * Links a dentry into the directory tree.
 *
 * @parent: The dentry that will be the parent of @child.
 * @child: The dentry to link.
 *
 * Returns non-NULL if a duplicate dentry was detected.
 */
struct wim_dentry *
dentry_add_child(struct wim_dentry * restrict parent,
                 struct wim_dentry * restrict child)
{
        wimlib_assert(dentry_is_directory(parent));
        wimlib_assert(parent != child);

        struct rb_root *root = &parent->d_inode->i_children;
        struct rb_node **new = &(root->rb_node);
        struct rb_node *rb_parent = NULL;

        while (*new) {
                struct wim_dentry *this = rbnode_dentry(*new);
                int result = dentry_compare_names(child, this);

                rb_parent = *new;

                if (result < 0)
                        new = &((*new)->rb_left);
                else if (result > 0)
                        new = &((*new)->rb_right);
                else
                        return this;
        }
        child->parent = parent;
        rb_link_node(&child->rb_node, rb_parent, new);
        rb_insert_color(&child->rb_node, root);
        return NULL;
}

/* Unlink a WIM dentry from the directory entry tree. */
void
unlink_dentry(struct wim_dentry *dentry)
{
        if (!dentry_is_root(dentry))
                rb_erase(&dentry->rb_node, &dentry->parent->d_inode->i_children);
}

/*
 * Returns the alternate data stream entry belonging to @inode that has the
 * stream name @stream_name.
 */
struct wim_ads_entry *
inode_get_ads_entry(struct wim_inode *inode, const tchar *stream_name,
                    u16 *idx_ret)
{
        if (inode->i_num_ads == 0) {
                return NULL;
        } else {
                size_t stream_name_utf16le_nbytes;
                u16 i;
                struct wim_ads_entry *result;

        #if TCHAR_IS_UTF16LE
                const utf16lechar *stream_name_utf16le;

                stream_name_utf16le = stream_name;
                stream_name_utf16le_nbytes = tstrlen(stream_name) * sizeof(tchar);
        #else
                utf16lechar *stream_name_utf16le;

                {
                        int ret = tstr_to_utf16le(stream_name,
                                                  tstrlen(stream_name) *
                                                      sizeof(tchar),
                                                  &stream_name_utf16le,
                                                  &stream_name_utf16le_nbytes);
                        if (ret)
                                return NULL;
                }
        #endif
                i = 0;
                result = NULL;
                do {
                        if (ads_entry_has_name(&inode->i_ads_entries[i],
                                               stream_name_utf16le,
                                               stream_name_utf16le_nbytes))
                        {
                                if (idx_ret)
                                        *idx_ret = i;
                                result = &inode->i_ads_entries[i];
                                break;
                        }
                } while (++i != inode->i_num_ads);
        #if !TCHAR_IS_UTF16LE
                FREE(stream_name_utf16le);
        #endif
                return result;
        }
}

static struct wim_ads_entry *
do_inode_add_ads(struct wim_inode *inode, const void *stream_name,
                 size_t stream_name_nbytes, bool is_utf16le)
{
        u16 num_ads;
        struct wim_ads_entry *ads_entries;
        struct wim_ads_entry *new_entry;

        if (inode->i_num_ads >= 0xfffe) {
                ERROR("Too many alternate data streams in one inode!");
                return NULL;
        }
        num_ads = inode->i_num_ads + 1;
        ads_entries = REALLOC(inode->i_ads_entries,
                              num_ads * sizeof(inode->i_ads_entries[0]));
        if (!ads_entries) {
                ERROR("Failed to allocate memory for new alternate data stream");
                return NULL;
        }
        inode->i_ads_entries = ads_entries;

        new_entry = &inode->i_ads_entries[num_ads - 1];
        if (init_ads_entry(new_entry, stream_name, stream_name_nbytes, is_utf16le))
                return NULL;
        new_entry->stream_id = inode->i_next_stream_id++;
        inode->i_num_ads = num_ads;
        return new_entry;
}

struct wim_ads_entry *
inode_add_ads_utf16le(struct wim_inode *inode,
                      const utf16lechar *stream_name,
                      size_t stream_name_nbytes)
{
        DEBUG("Add alternate data stream \"%"WS"\"", stream_name);
        return do_inode_add_ads(inode, stream_name, stream_name_nbytes, true);
}

/*
 * Add an alternate stream entry to a WIM inode and return a pointer to it, or
 * NULL if memory could not be allocated.
 */
struct wim_ads_entry *
inode_add_ads(struct wim_inode *inode, const tchar *stream_name)
{
        DEBUG("Add alternate data stream \"%"TS"\"", stream_name);
        return do_inode_add_ads(inode, stream_name,
                                tstrlen(stream_name) * sizeof(tchar),
                                TCHAR_IS_UTF16LE);
}

static struct wim_lookup_table_entry *
add_stream_from_data_buffer(const void *buffer, size_t size,
                            struct wim_lookup_table *lookup_table)
{
        u8 hash[SHA1_HASH_SIZE];
        struct wim_lookup_table_entry *lte, *existing_lte;

        sha1_buffer(buffer, size, hash);
        existing_lte = __lookup_resource(lookup_table, hash);
        if (existing_lte) {
                wimlib_assert(wim_resource_size(existing_lte) == size);
                lte = existing_lte;
                lte->refcnt++;
        } else {
                void *buffer_copy;
                lte = new_lookup_table_entry();
                if (!lte)
                        return NULL;
                buffer_copy = MALLOC(size);
                if (!buffer_copy) {
                        free_lookup_table_entry(lte);
                        return NULL;
                }
                memcpy(buffer_copy, buffer, size);
                lte->resource_location            = RESOURCE_IN_ATTACHED_BUFFER;
                lte->attached_buffer              = buffer_copy;
                lte->resource_entry.original_size = size;
                copy_hash(lte->hash, hash);
                lookup_table_insert(lookup_table, lte);
        }
        return lte;
}

int
inode_add_ads_with_data(struct wim_inode *inode, const tchar *name,
                        const void *value, size_t size,
                        struct wim_lookup_table *lookup_table)
{
        struct wim_ads_entry *new_ads_entry;

        wimlib_assert(inode->i_resolved);

        new_ads_entry = inode_add_ads(inode, name);
        if (!new_ads_entry)
                return WIMLIB_ERR_NOMEM;

        new_ads_entry->lte = add_stream_from_data_buffer(value, size,
                                                         lookup_table);
        if (!new_ads_entry->lte) {
                inode_remove_ads(inode, new_ads_entry - inode->i_ads_entries,
                                 lookup_table);
                return WIMLIB_ERR_NOMEM;
        }
        return 0;
}

/* Set the unnamed stream of a WIM inode, given a data buffer containing the
 * stream contents. */
int
inode_set_unnamed_stream(struct wim_inode *inode, const void *data, size_t len,
                         struct wim_lookup_table *lookup_table)
{
        inode->i_lte = add_stream_from_data_buffer(data, len, lookup_table);
        if (!inode->i_lte)
                return WIMLIB_ERR_NOMEM;
        inode->i_resolved = 1;
        return 0;
}

/* Remove an alternate data stream from a WIM inode  */
void
inode_remove_ads(struct wim_inode *inode, u16 idx,
                 struct wim_lookup_table *lookup_table)
{
        struct wim_ads_entry *ads_entry;
        struct wim_lookup_table_entry *lte;

        wimlib_assert(idx < inode->i_num_ads);
        wimlib_assert(inode->i_resolved);

        ads_entry = &inode->i_ads_entries[idx];

        DEBUG("Remove alternate data stream \"%"WS"\"", ads_entry->stream_name);

        lte = ads_entry->lte;
        if (lte)
                lte_decrement_refcnt(lte, lookup_table);

        destroy_ads_entry(ads_entry);

        memmove(&inode->i_ads_entries[idx],
                &inode->i_ads_entries[idx + 1],
                (inode->i_num_ads - idx - 1) * sizeof(inode->i_ads_entries[0]));
        inode->i_num_ads--;
}

#ifndef __WIN32__
int
inode_get_unix_data(const struct wim_inode *inode,
                    struct wimlib_unix_data *unix_data,
                    u16 *stream_idx_ret)
{
        const struct wim_ads_entry *ads_entry;
        const struct wim_lookup_table_entry *lte;
        size_t size;
        int ret;

        wimlib_assert(inode->i_resolved);

        ads_entry = inode_get_ads_entry((struct wim_inode*)inode,
                                        WIMLIB_UNIX_DATA_TAG, NULL);
        if (!ads_entry)
                return NO_UNIX_DATA;

        if (stream_idx_ret)
                *stream_idx_ret = ads_entry - inode->i_ads_entries;

        lte = ads_entry->lte;
        if (!lte)
                return NO_UNIX_DATA;

        size = wim_resource_size(lte);
        if (size != sizeof(struct wimlib_unix_data))
                return BAD_UNIX_DATA;

        ret = read_full_resource_into_buf(lte, unix_data);
        if (ret)
                return ret;

        if (unix_data->version != 0)
                return BAD_UNIX_DATA;
        return 0;
}

int
inode_set_unix_data(struct wim_inode *inode, uid_t uid, gid_t gid, mode_t mode,
                    struct wim_lookup_table *lookup_table, int which)
{
        struct wimlib_unix_data unix_data;
        int ret;
        bool have_good_unix_data = false;
        bool have_unix_data = false;
        u16 stream_idx;

        if (!(which & UNIX_DATA_CREATE)) {
                ret = inode_get_unix_data(inode, &unix_data, &stream_idx);
                if (ret == 0 || ret == BAD_UNIX_DATA || ret > 0)
                        have_unix_data = true;
                if (ret == 0)
                        have_good_unix_data = true;
        }
        unix_data.version = 0;
        if (which & UNIX_DATA_UID || !have_good_unix_data)
                unix_data.uid = uid;
        if (which & UNIX_DATA_GID || !have_good_unix_data)
                unix_data.gid = gid;
        if (which & UNIX_DATA_MODE || !have_good_unix_data)
                unix_data.mode = mode;
        ret = inode_add_ads_with_data(inode, WIMLIB_UNIX_DATA_TAG,
                                      &unix_data,
                                      sizeof(struct wimlib_unix_data),
                                      lookup_table);
        if (ret == 0 && have_unix_data)
                inode_remove_ads(inode, stream_idx, lookup_table);
        return ret;
}
#endif /* !__WIN32__ */

/* Replace weird characters in filenames and alternate data stream names.
 *
 * In particular we do not want the path separator to appear in any names, as
 * that would make it possible for a "malicious" WIM to extract itself to any
 * location it wanted to. */
static void
replace_forbidden_characters(utf16lechar *name)
{
        utf16lechar *p;

        for (p = name; *p; p++) {
        #ifdef __WIN32__
                if (wcschr(L"<>:\"/\\|?*", (wchar_t)*p))
        #else
                if (*p == cpu_to_le16('/'))
        #endif
                {
                        if (name) {
                                WARNING("File, directory, or stream name \"%"WS"\"\n"
                                        "          contains forbidden characters; "
                                        "substituting replacement characters.",
                                        name);
                                name = NULL;
                        }
                #ifdef __WIN32__
                        *p = cpu_to_le16(0xfffd);
                #else
                        *p = cpu_to_le16('?');
                #endif
                }
        }
}

/*
 * Reads the alternate data stream entries of a WIM dentry.
 *
 * @p:  Pointer to buffer that starts with the first alternate stream entry.
 *
 * @inode:      Inode to load the alternate data streams into.
 *              @inode->i_num_ads must have been set to the number of
 *              alternate data streams that are expected.
 *
 * @remaining_size:     Number of bytes of data remaining in the buffer pointed
 *                      to by @p.
 *
 *
 * Return 0 on success or nonzero on failure.  On success, inode->i_ads_entries
 * is set to an array of `struct wim_ads_entry's of length inode->i_num_ads.  On
 * failure, @inode is not modified.
 */
static int
read_ads_entries(const u8 * restrict p, struct wim_inode * restrict inode,
                 size_t nbytes_remaining)
{
        u16 num_ads;
        struct wim_ads_entry *ads_entries;
        int ret;

        /* Allocate an array for our in-memory representation of the alternate
         * data stream entries. */
        num_ads = inode->i_num_ads;
        ads_entries = CALLOC(num_ads, sizeof(inode->i_ads_entries[0]));
        if (!ads_entries)
                goto out_of_memory;

        /* Read the entries into our newly allocated buffer. */
        for (u16 i = 0; i < num_ads; i++) {
                u64 length;
                struct wim_ads_entry *cur_entry;
                const struct wim_ads_entry_on_disk *disk_entry =
                        (const struct wim_ads_entry_on_disk*)p;

                cur_entry = &ads_entries[i];
                ads_entries[i].stream_id = i + 1;

                /* Do we have at least the size of the fixed-length data we know
                 * need? */
                if (nbytes_remaining < sizeof(struct wim_ads_entry_on_disk))
                        goto out_invalid;

                /* Read the length field */
                length = le64_to_cpu(disk_entry->length);

                /* Make sure the length field is neither so small it doesn't
                 * include all the fixed-length data nor so large it overflows
                 * the metadata resource buffer. */
                if (length < sizeof(struct wim_ads_entry_on_disk) ||
                    length > nbytes_remaining)
                        goto out_invalid;

                /* Read the rest of the fixed-length data. */

                cur_entry->reserved = le64_to_cpu(disk_entry->reserved);
                copy_hash(cur_entry->hash, disk_entry->hash);
                cur_entry->stream_name_nbytes = le16_to_cpu(disk_entry->stream_name_nbytes);

                /* If stream_name_nbytes != 0, this is a named stream.
                 * Otherwise this is an unnamed stream, or in some cases (bugs
                 * in Microsoft's software I guess) a meaningless entry
                 * distinguished from the real unnamed stream entry, if any, by
                 * the fact that the real unnamed stream entry has a nonzero
                 * hash field. */
                if (cur_entry->stream_name_nbytes) {
                        /* The name is encoded in UTF16-LE, which uses 2-byte
                         * coding units, so the length of the name had better be
                         * an even number of bytes... */
                        if (cur_entry->stream_name_nbytes & 1)
                                goto out_invalid;

                        /* Add the length of the stream name to get the length
                         * we actually need to read.  Make sure this isn't more
                         * than the specified length of the entry. */
                        if (sizeof(struct wim_ads_entry_on_disk) +
                            cur_entry->stream_name_nbytes > length)
                                goto out_invalid;

                        cur_entry->stream_name = MALLOC(cur_entry->stream_name_nbytes + 2);
                        if (!cur_entry->stream_name)
                                goto out_of_memory;

                        memcpy(cur_entry->stream_name,
                               disk_entry->stream_name,
                               cur_entry->stream_name_nbytes);
                        cur_entry->stream_name[cur_entry->stream_name_nbytes / 2] = cpu_to_le16(0);
                        replace_forbidden_characters(cur_entry->stream_name);
                }

                /* It's expected that the size of every ADS entry is a multiple
                 * of 8.  However, to be safe, I'm allowing the possibility of
                 * an ADS entry at the very end of the metadata resource ending
                 * un-aligned.  So although we still need to increment the input
                 * pointer by @length to reach the next ADS entry, it's possible
                 * that less than @length is actually remaining in the metadata
                 * resource. We should set the remaining bytes to 0 if this
                 * happens. */
                length = (length + 7) & ~(u64)7;
                p += length;
                if (nbytes_remaining < length)
                        nbytes_remaining = 0;
                else
                        nbytes_remaining -= length;
        }
        inode->i_ads_entries = ads_entries;
        inode->i_next_stream_id = inode->i_num_ads + 1;
        ret = 0;
        goto out;
out_of_memory:
        ret = WIMLIB_ERR_NOMEM;
        goto out_free_ads_entries;
out_invalid:
        ERROR("An alternate data stream entry is invalid");
        ret = WIMLIB_ERR_INVALID_DENTRY;
out_free_ads_entries:
        if (ads_entries) {
                for (u16 i = 0; i < num_ads; i++)
                        destroy_ads_entry(&ads_entries[i]);
                FREE(ads_entries);
        }
out:
        return ret;
}

/*
 * Reads a WIM directory entry, including all alternate data stream entries that
 * follow it, from the WIM image's metadata resource.
 *
 * @metadata_resource:
 *              Pointer to the metadata resource buffer.
 *
 * @metadata_resource_len:
 *              Length of the metadata resource buffer, in bytes.
 *
 * @offset:     Offset of the dentry within the metadata resource.
 *
 * @dentry:     A `struct wim_dentry' that will be filled in by this function.
 *
 * Return 0 on success or nonzero on failure.  On failure, @dentry will have
 * been modified, but it will not be left with pointers to any allocated
 * buffers.  On success, the dentry->length field must be examined.  If zero,
 * this was a special "end of directory" dentry and not a real dentry.  If
 * nonzero, this was a real dentry.
 *
 * Possible errors include:
 *      WIMLIB_ERR_NOMEM
 *      WIMLIB_ERR_INVALID_DENTRY
 */
int
read_dentry(const u8 * restrict metadata_resource, u64 metadata_resource_len,
            u64 offset, struct wim_dentry * restrict dentry)
{

        u64 calculated_size;
        utf16lechar *file_name;
        utf16lechar *short_name;
        u16 short_name_nbytes;
        u16 file_name_nbytes;
        int ret;
        struct wim_inode *inode;
        const u8 *p = &metadata_resource[offset];
        const struct wim_dentry_on_disk *disk_dentry =
                        (const struct wim_dentry_on_disk*)p;

        if ((uintptr_t)p & 7)
                WARNING("WIM dentry is not 8-byte aligned");

        dentry_common_init(dentry);

        /* Before reading the whole dentry, we need to read just the length.
         * This is because a dentry of length 8 (that is, just the length field)
         * terminates the list of sibling directory entries. */
        if (offset + sizeof(u64) > metadata_resource_len ||
            offset + sizeof(u64) < offset)
        {
                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;
        }
        dentry->length = le64_to_cpu(disk_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 successfully in this case. */
        if (dentry->length == 8)
                dentry->length = 0;
        if (dentry->length == 0)
                return 0;

        /* Now that we have the actual length provided in the on-disk structure,
         * again make sure it doesn't overflow the metadata resource buffer. */
        if (offset + dentry->length > metadata_resource_len ||
            offset + dentry->length < offset)
        {
                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;
        }

        /* Make sure the dentry length is at least as large as the number of
         * fixed-length fields */
        if (dentry->length < sizeof(struct wim_dentry_on_disk)) {
                ERROR("Directory entry has invalid length of %"PRIu64" bytes",
                      dentry->length);
                return WIMLIB_ERR_INVALID_DENTRY;
        }

        /* Allocate a `struct wim_inode' for this `struct wim_dentry'. */
        inode = new_timeless_inode();
        if (!inode)
                return WIMLIB_ERR_NOMEM;

        /* Read more fields; some into the dentry, and some into the inode. */

        inode->i_attributes = le32_to_cpu(disk_dentry->attributes);
        inode->i_security_id = le32_to_cpu(disk_dentry->security_id);
        dentry->subdir_offset = le64_to_cpu(disk_dentry->subdir_offset);
        dentry->d_unused_1 = le64_to_cpu(disk_dentry->unused_1);
        dentry->d_unused_2 = le64_to_cpu(disk_dentry->unused_2);
        inode->i_creation_time = le64_to_cpu(disk_dentry->creation_time);
        inode->i_last_access_time = le64_to_cpu(disk_dentry->last_access_time);
        inode->i_last_write_time = le64_to_cpu(disk_dentry->last_write_time);
        copy_hash(inode->i_hash, disk_dentry->unnamed_stream_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.  So we have some fields we read for reparse points, and
         * some fields in the same place for non-reparse-point.s */
        if (inode->i_attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
                inode->i_rp_unknown_1 = le32_to_cpu(disk_dentry->reparse.rp_unknown_1);
                inode->i_reparse_tag = le32_to_cpu(disk_dentry->reparse.reparse_tag);
                inode->i_rp_unknown_2 = le16_to_cpu(disk_dentry->reparse.rp_unknown_2);
                inode->i_not_rpfixed = le16_to_cpu(disk_dentry->reparse.not_rpfixed);
                /* Leave inode->i_ino at 0.  Note that this means the WIM file
                 * cannot archive hard-linked reparse points.  Such a thing
                 * doesn't really make sense anyway, although I believe it's
                 * theoretically possible to have them on NTFS. */
        } else {
                inode->i_rp_unknown_1 = le32_to_cpu(disk_dentry->nonreparse.rp_unknown_1);
                inode->i_ino = le64_to_cpu(disk_dentry->nonreparse.hard_link_group_id);
        }

        inode->i_num_ads = le16_to_cpu(disk_dentry->num_alternate_data_streams);

        short_name_nbytes = le16_to_cpu(disk_dentry->short_name_nbytes);
        file_name_nbytes = le16_to_cpu(disk_dentry->file_name_nbytes);

        if ((short_name_nbytes & 1) | (file_name_nbytes & 1))
        {
                ERROR("Dentry name is not valid UTF-16LE (odd number of bytes)!");
                ret = WIMLIB_ERR_INVALID_DENTRY;
                goto out_free_inode;
        }

        /* We now know the length of the file name and short name.  Make sure
         * the length of the dentry is large enough to actually hold them.
         *
         * The calculated length here is unaligned to allow for the possibility
         * that the dentry->length names an unaligned length, although this
         * would be unexpected. */
        calculated_size = _dentry_correct_length_unaligned(file_name_nbytes,
                                                           short_name_nbytes);

        if (dentry->length < calculated_size) {
                ERROR("Unexpected end of directory entry! (Expected "
                      "at least %"PRIu64" bytes, got %"PRIu64" bytes.)",
                      calculated_size, dentry->length);
                ret = WIMLIB_ERR_INVALID_DENTRY;
                goto out_free_inode;
        }

        p += sizeof(struct wim_dentry_on_disk);

        /* Read the filename if present.  Note: if the filename is empty, there
         * is no null terminator following it. */
        if (file_name_nbytes) {
                file_name = MALLOC(file_name_nbytes + 2);
                if (!file_name) {
                        ERROR("Failed to allocate %d bytes for dentry file name",
                              file_name_nbytes + 2);
                        ret = WIMLIB_ERR_NOMEM;
                        goto out_free_inode;
                }
                memcpy(file_name, p, file_name_nbytes);
                p += file_name_nbytes + 2;
                file_name[file_name_nbytes / 2] = cpu_to_le16(0);
                replace_forbidden_characters(file_name);
        } else {
                file_name = NULL;
        }


        /* Read the short filename if present.  Note: if there is no short
         * filename, there is no null terminator following it. */
        if (short_name_nbytes) {
                short_name = MALLOC(short_name_nbytes + 2);
                if (!short_name) {
                        ERROR("Failed to allocate %d bytes for dentry short name",
                              short_name_nbytes + 2);
                        ret = WIMLIB_ERR_NOMEM;
                        goto out_free_file_name;
                }
                memcpy(short_name, p, short_name_nbytes);
                p += short_name_nbytes + 2;
                short_name[short_name_nbytes / 2] = cpu_to_le16(0);
                replace_forbidden_characters(short_name);
        } else {
                short_name = NULL;
        }

        /* Align the dentry length */
        dentry->length = (dentry->length + 7) & ~7;

        /*
         * Read the alternate data streams, if present.  dentry->num_ads tells
         * us how many they are, and they will directly follow the dentry
         * on-disk.
         *
         * Note that each alternate data stream entry begins on an 8-byte
         * aligned boundary, and the alternate data stream entries seem to NOT
         * be included in the dentry->length field for some reason.
         */
        if (inode->i_num_ads != 0) {
                ret = WIMLIB_ERR_INVALID_DENTRY;
                if (offset + dentry->length > metadata_resource_len ||
                    (ret = read_ads_entries(&metadata_resource[offset + dentry->length],
                                            inode,
                                            metadata_resource_len - offset - dentry->length)))
                {
                        ERROR("Failed to read alternate data stream "
                              "entries of WIM dentry \"%"WS"\"", file_name);
                        goto out_free_short_name;
                }
        }
        /* We've read all the data for this dentry.  Set the names and their
         * lengths, and we've done. */
        dentry->d_inode           = inode;
        dentry->file_name         = file_name;
        dentry->short_name        = short_name;
        dentry->file_name_nbytes  = file_name_nbytes;
        dentry->short_name_nbytes = short_name_nbytes;
        ret = 0;
        goto out;
out_free_short_name:
        FREE(short_name);
out_free_file_name:
        FREE(file_name);
out_free_inode:
        free_inode(inode);
out:
        return ret;
}

/* 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 the uncompressed metadata resource, in
 *                          bytes.
 *
 * @dentry:     A pointer to a `struct wim_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.
 *
 * Returns zero on success; nonzero on failure.
 */
int
read_dentry_tree(const u8 metadata_resource[], u64 metadata_resource_len,
                 struct wim_dentry *dentry)
{
        u64 cur_offset = dentry->subdir_offset;
        struct wim_dentry *child;
        struct wim_dentry cur_child;
        int ret;

        /*
         * If @dentry has no child dentries, nothing more needs to be done for
         * this branch.  This is the case for regular files, symbolic links, and
         * *possibly* empty directories (although an empty directory may also
         * have one child dentry that is the special end-of-directory dentry)
         */
        if (cur_offset == 0)
                return 0;

        /* Find and read all the children of @dentry. */
        for (;;) {

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

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

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

                /* Advance to the offset of the next child.  Note: We need to
                 * advance by the TOTAL length of the dentry, not by the length
                 * cur_child.length, which although it does take into account
                 * the padding, it DOES NOT take into account alternate stream
                 * entries. */
                cur_offset += dentry_total_length(child);

                if (dentry_add_child(dentry, child)) {
                        WARNING("Ignoring duplicate dentry \"%"WS"\"",
                                child->file_name);
                        WARNING("(In directory \"%"TS"\")", dentry_full_path(dentry));
                        free_dentry(child);
                } else {
                        inode_add_dentry(child, child->d_inode);
                        /* If there are children of this child, call this
                         * procedure recursively. */
                        if (child->subdir_offset != 0) {
                                if (!dentry_is_directory(child)) {
                                        ret = read_dentry_tree(metadata_resource,
                                                               metadata_resource_len,
                                                               child);
                                        if (ret)
                                                break;
                                } else {
                                        WARNING("Ignoring children of non-directory \"%"TS"\"",
                                                dentry_full_path(child));
                                }
                        }

                }
        }
        return ret;
}

/*
 * Writes a WIM dentry to an output buffer.
 *
 * @dentry:  The dentry structure.
 * @p:       The memory location to write the data to.
 *
 * Returns the pointer to the byte after the last byte we wrote as part of the
 * dentry, including any alternate data stream entries.
 */
static u8 *
write_dentry(const struct wim_dentry * restrict dentry, u8 * restrict p)
{
        const struct wim_inode *inode;
        struct wim_dentry_on_disk *disk_dentry;
        const u8 *orig_p;
        const u8 *hash;

        wimlib_assert(((uintptr_t)p & 7) == 0); /* 8 byte aligned */
        orig_p = p;

        inode = dentry->d_inode;
        disk_dentry = (struct wim_dentry_on_disk*)p;

        disk_dentry->attributes = cpu_to_le32(inode->i_attributes);
        disk_dentry->security_id = cpu_to_le32(inode->i_security_id);
        disk_dentry->subdir_offset = cpu_to_le64(dentry->subdir_offset);
        disk_dentry->unused_1 = cpu_to_le64(dentry->d_unused_1);
        disk_dentry->unused_2 = cpu_to_le64(dentry->d_unused_2);
        disk_dentry->creation_time = cpu_to_le64(inode->i_creation_time);
        disk_dentry->last_access_time = cpu_to_le64(inode->i_last_access_time);
        disk_dentry->last_write_time = cpu_to_le64(inode->i_last_write_time);
        hash = inode_stream_hash(inode, 0);
        copy_hash(disk_dentry->unnamed_stream_hash, hash);
        if (inode->i_attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
                disk_dentry->reparse.rp_unknown_1 = cpu_to_le32(inode->i_rp_unknown_1);
                disk_dentry->reparse.reparse_tag = cpu_to_le32(inode->i_reparse_tag);
                disk_dentry->reparse.rp_unknown_2 = cpu_to_le16(inode->i_rp_unknown_2);
                disk_dentry->reparse.not_rpfixed = cpu_to_le16(inode->i_not_rpfixed);
        } else {
                disk_dentry->nonreparse.rp_unknown_1 = cpu_to_le32(inode->i_rp_unknown_1);
                disk_dentry->nonreparse.hard_link_group_id =
                        cpu_to_le64((inode->i_nlink == 1) ? 0 : inode->i_ino);
        }
        disk_dentry->num_alternate_data_streams = cpu_to_le16(inode->i_num_ads);
        disk_dentry->short_name_nbytes = cpu_to_le16(dentry->short_name_nbytes);
        disk_dentry->file_name_nbytes = cpu_to_le16(dentry->file_name_nbytes);
        p += sizeof(struct wim_dentry_on_disk);

        if (dentry_has_long_name(dentry))
                p = mempcpy(p, dentry->file_name, dentry->file_name_nbytes + 2);

        if (dentry_has_short_name(dentry))
                p = mempcpy(p, dentry->short_name, dentry->short_name_nbytes + 2);

        /* Align to 8-byte boundary */
        while ((uintptr_t)p & 7)
                *p++ = 0;

        /* We calculate the correct length of the dentry ourselves because the
         * dentry->length field may been set to an unexpected value from when we
         * read the dentry in (for example, there may have been unknown data
         * appended to the end of the dentry...).  Furthermore, the dentry may
         * have been renamed, thus changing its needed length. */
        disk_dentry->length = cpu_to_le64(p - orig_p);

        /* Write the alternate data streams entries, if any. */
        for (u16 i = 0; i < inode->i_num_ads; i++) {
                const struct wim_ads_entry *ads_entry =
                                &inode->i_ads_entries[i];
                struct wim_ads_entry_on_disk *disk_ads_entry =
                                (struct wim_ads_entry_on_disk*)p;
                orig_p = p;

                disk_ads_entry->reserved = cpu_to_le64(ads_entry->reserved);

                hash = inode_stream_hash(inode, i + 1);
                copy_hash(disk_ads_entry->hash, hash);
                disk_ads_entry->stream_name_nbytes = cpu_to_le16(ads_entry->stream_name_nbytes);
                p += sizeof(struct wim_ads_entry_on_disk);
                if (ads_entry->stream_name_nbytes) {
                        p = mempcpy(p, ads_entry->stream_name,
                                    ads_entry->stream_name_nbytes + 2);
                }
                /* Align to 8-byte boundary */
                while ((uintptr_t)p & 7)
                        *p++ = 0;
                disk_ads_entry->length = cpu_to_le64(p - orig_p);
        }
        return p;
}

static int
write_dentry_cb(struct wim_dentry *dentry, void *_p)
{
        u8 **p = _p;
        *p = write_dentry(dentry, *p);
        return 0;
}

static u8 *
write_dentry_tree_recursive(const struct wim_dentry *parent, u8 *p);

static int
write_dentry_tree_recursive_cb(struct wim_dentry *dentry, void *_p)
{
        u8 **p = _p;
        *p = write_dentry_tree_recursive(dentry, *p);
        return 0;
}

/* Recursive function that writes a dentry tree rooted at @parent, not including
 * @parent itself, which has already been written. */
static u8 *
write_dentry_tree_recursive(const struct wim_dentry *parent, u8 *p)
{
        /* Nothing to do if this dentry has no children. */
        if (parent->subdir_offset == 0)
                return p;

        /* Write child dentries and end-of-directory entry.
         *
         * Note: we need to write all of this dentry's children before
         * recursively writing the directory trees rooted at each of the child
         * dentries, since the on-disk dentries for a dentry's children are
         * always located at consecutive positions in the metadata resource! */
        for_dentry_child(parent, write_dentry_cb, &p);

        /* write end of directory entry */
        *(le64*)p = cpu_to_le64(0);
        p += 8;

        /* Recurse on children. */
        for_dentry_child(parent, write_dentry_tree_recursive_cb, &p);
        return p;
}

/* Writes a directory tree to the metadata resource.
 *
 * @root:       Root of the dentry tree.
 * @p:          Pointer to a buffer with enough space for the dentry tree.
 *
 * Returns pointer to the byte after the last byte we wrote.
 */
u8 *
write_dentry_tree(const struct wim_dentry *root, u8 *p)
{
        DEBUG("Writing dentry tree.");
        wimlib_assert(dentry_is_root(root));

        /* If we're the root dentry, we have no parent that already
         * wrote us, so we need to write ourselves. */
        p = write_dentry(root, p);

        /* Write end of directory entry after the root dentry just to be safe;
         * however the root dentry obviously cannot have any siblings. */
        *(le64*)p = cpu_to_le64(0);
        p += 8;

        /* Recursively write the rest of the dentry tree. */
        return write_dentry_tree_recursive(root, p);
}