[wimlib] / src / inode.c

/*
 * inode.c
 *
 * Functions that operate on WIM inodes.
 *
 * See dentry.c for a description of the relationship between WIM dentries and
 * WIM inodes.
 */

/*
 * Copyright (C) 2012, 2013, 2014 Eric Biggers
 *
 * This file 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 3 of the License, or (at your option) any
 * later version.
 *
 * This file 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 this file; if not, see http://www.gnu.org/licenses/.
 */

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

#include "wimlib/assert.h"
#include "wimlib/dentry.h" /* Only for dentry_full_path().  Otherwise the code
                              in this file doesn't care about file names/paths.
                            */
#include "wimlib/encoding.h"
#include "wimlib/endianness.h"
#include "wimlib/error.h"
#include "wimlib/inode.h"
#include "wimlib/inode_table.h"
#include "wimlib/lookup_table.h"
#include "wimlib/security.h"
#include "wimlib/timestamp.h"

#include <errno.h>

/* Allocate a new inode.  Set the timestamps to the current time.  */
struct wim_inode *
new_inode(void)
{
        struct wim_inode *inode = new_timeless_inode();
        if (inode) {
                u64 now = now_as_wim_timestamp();
                inode->i_creation_time = now;
                inode->i_last_access_time = now;
                inode->i_last_write_time = now;
        }
        return inode;
}

/* Allocate a new inode.  Leave the timestamps zeroed out.  */
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;
                inode->i_canonical_streams = 1;
                INIT_LIST_HEAD(&inode->i_list);
                INIT_LIST_HEAD(&inode->i_dentry);
        }
        return inode;
}

/* Decrement link count on an inode.  */
void
put_inode(struct wim_inode *inode)
{
        wimlib_assert(inode->i_nlink != 0);
        if (--inode->i_nlink == 0) {
                /* If FUSE mounts are enabled, we must keep a unlinked inode
                 * around until all file descriptors to it have been closed.  */
        #ifdef WITH_FUSE
                if (inode->i_num_opened_fds == 0)
        #endif
                        free_inode(inode);
        }
}

/* Free memory allocated within an alternate data stream entry.  */
static void
destroy_ads_entry(struct wim_ads_entry *ads_entry)
{
        FREE(ads_entry->stream_name);
}

/* Free an inode.  Only use this if there can't be other links to the inode or
 * if it doesn't matter if there are.  */
void
free_inode(struct wim_inode *inode)
{
        if (unlikely(!inode))
                return;

        if (unlikely(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);
        }
        if (unlikely(inode->i_extra))
                FREE(inode->i_extra);
        /* HACK: This may instead delete the inode from i_list, but hlist_del()
         * behaves the same as list_del(). */
        if (!hlist_unhashed(&inode->i_hlist))
                hlist_del(&inode->i_hlist);
        FREE(inode);
}

/* 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,
                   bool ignore_case)
{
        return 0 == cmp_utf16le_strings(name,
                                        name_nbytes / 2,
                                        entry->stream_name,
                                        entry->stream_name_nbytes / 2,
                                        ignore_case);
}

/*
 * Returns the alternate data stream entry belonging to @inode that has the
 * stream name @stream_name, or NULL if the inode has no alternate data stream
 * with that name.
 *
 * If @p stream_name is the empty string, NULL is returned --- that is, this
 * function will not return "unnamed" alternate data stream entries.
 *
 * If NULL is returned, errno is set.
 */
struct wim_ads_entry *
inode_get_ads_entry(struct wim_inode *inode, const tchar *stream_name)
{
        int ret;
        const utf16lechar *stream_name_utf16le;
        size_t stream_name_utf16le_nbytes;
        u16 i;
        struct wim_ads_entry *result;

        if (inode->i_num_ads == 0) {
                errno = ENOENT;
                return NULL;
        }

        if (stream_name[0] == T('\0')) {
                errno = ENOENT;
                return NULL;
        }

        ret = tstr_get_utf16le_and_len(stream_name, &stream_name_utf16le,
                                       &stream_name_utf16le_nbytes);
        if (ret)
                return NULL;

        i = 0;
        result = NULL;
        do {
                if (ads_entry_has_name(&inode->i_ads_entries[i],
                                       stream_name_utf16le,
                                       stream_name_utf16le_nbytes,
                                       default_ignore_case))
                {
                        result = &inode->i_ads_entries[i];
                        break;
                }
        } while (++i != inode->i_num_ads);

        tstr_put_utf16le(stream_name_utf16le);

        if (!result)
                errno = ENOENT;
        return result;
}

static struct wim_ads_entry *
do_inode_add_ads(struct wim_inode *inode,
                 utf16lechar *stream_name, size_t stream_name_nbytes)
{
        u16 num_ads;
        struct wim_ads_entry *ads_entries;
        struct wim_ads_entry *new_entry;

        if (inode->i_num_ads >= 0xfffe) {
                ERROR("File \"%"TS"\" has too many alternate data streams!",
                      inode_first_full_path(inode));
                errno = EFBIG;
                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)
                return NULL;

        inode->i_ads_entries = ads_entries;

        new_entry = &inode->i_ads_entries[num_ads - 1];

        memset(new_entry, 0, sizeof(struct wim_ads_entry));
        new_entry->stream_name = stream_name;
        new_entry->stream_name_nbytes = stream_name_nbytes;
        new_entry->stream_id = inode->i_next_stream_id++;
        inode->i_num_ads = num_ads;
        return new_entry;
}

/*
 * Add an alternate data stream entry to a WIM inode (UTF-16LE version).  On
 * success, returns a pointer to the new entry.  Note that this pointer might
 * become invalid if another ADS entry is added to the inode.  On failure,
 * returns NULL and sets errno.
 */
struct wim_ads_entry *
inode_add_ads_utf16le(struct wim_inode *inode,
                      const utf16lechar *stream_name, size_t stream_name_nbytes)
{
        utf16lechar *dup = NULL;
        struct wim_ads_entry *result;

        if (stream_name_nbytes) {
                dup = utf16le_dupz(stream_name, stream_name_nbytes);
                if (!dup)
                        return NULL;
        }

        result = do_inode_add_ads(inode, dup, stream_name_nbytes);
        if (!result)
                FREE(dup);
        return result;
}

/*
 * Add an alternate data stream entry to a WIM inode (tchar version).  On
 * success, returns a pointer to the new entry.  Note that this pointer might
 * become invalid if another ADS entry is added to the inode.  On failure,
 * returns NULL and sets errno.
 */
struct wim_ads_entry *
inode_add_ads(struct wim_inode *inode, const tchar *stream_name)
{
        utf16lechar *stream_name_utf16le = NULL;
        size_t stream_name_utf16le_nbytes = 0;
        struct wim_ads_entry *result;

        if (stream_name && *stream_name)
                if (tstr_to_utf16le(stream_name,
                                    tstrlen(stream_name) * sizeof(tchar),
                                    &stream_name_utf16le,
                                    &stream_name_utf16le_nbytes))
                        return NULL;

        result = do_inode_add_ads(inode, stream_name_utf16le,
                                  stream_name_utf16le_nbytes);
        if (!result)
                FREE(stream_name_utf16le);
        return result;
}

/*
 * Add an data alternate stream entry to a WIM inode, where the contents of the
 * new stream are specified in a data buffer.  The inode must be resolved.
 *
 * On success, returns a pointer to the new alternate data stream entry.  Note
 * that this pointer might become invalid if another ADS entry is added to the
 * inode.  On failure, returns NULL and sets errno.
 */
struct wim_ads_entry *
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_entry;

        wimlib_assert(inode->i_resolved);

        new_entry = inode_add_ads(inode, name);
        if (!new_entry)
                return NULL;

        new_entry->lte = new_stream_from_data_buffer(value, size, lookup_table);
        if (!new_entry->lte) {
                inode_remove_ads(inode, new_entry, NULL);
                return NULL;
        }
        return new_entry;
}

/*
 * Does the inode have any named data streams?
 */
bool
inode_has_named_stream(const struct wim_inode *inode)
{
        for (u16 i = 0; i < inode->i_num_ads; i++)
                if (ads_entry_is_named_stream(&inode->i_ads_entries[i]))
                        return true;
        return false;
}

/* Set the unnamed stream of a WIM inode, given a data buffer containing the
 * stream contents.  The inode must be resolved and cannot have an unnamed
 * stream specified already.  */
int
inode_set_unnamed_stream(struct wim_inode *inode, const void *data, size_t len,
                         struct wim_lookup_table *lookup_table)
{
        wimlib_assert(inode->i_resolved);
        wimlib_assert(!inode->i_lte);
        inode->i_lte = new_stream_from_data_buffer(data, len, lookup_table);
        if (!inode->i_lte)
                return WIMLIB_ERR_NOMEM;
        return 0;
}

/* Remove an alternate data stream from a WIM inode.  */
void
inode_remove_ads(struct wim_inode *inode, struct wim_ads_entry *entry,
                 struct wim_lookup_table *lookup_table)
{
        struct wim_lookup_table_entry *lte;
        unsigned idx = entry - inode->i_ads_entries;

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

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

        destroy_ads_entry(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--;
}

/*
 * Resolve an inode's single-instance streams.
 *
 * This takes each SHA-1 message digest stored in the inode or one of its ADS
 * entries and replaces it with a pointer directly to the appropriate 'struct
 * wim_lookup_table_entry' currently inserted into @table to represent the
 * single-instance stream having that SHA-1 message digest.
 *
 * If @force is %false:
 *      If any of the needed single-instance streams do not exist in @table,
 *      return WIMLIB_ERR_RESOURCE_NOT_FOUND and leave the inode unmodified.
 * If @force is %true:
 *      If any of the needed single-instance streams do not exist in @table,
 *      allocate new entries for them and insert them into @table.  This does
 *      not, of course, cause these streams to magically exist, but this is
 *      needed by the code for extraction from a pipe.
 *
 * If the inode is already resolved, this function does nothing.
 *
 * Returns 0 on success; WIMLIB_ERR_NOMEM if out of memory; or
 * WIMLIB_ERR_RESOURCE_NOT_FOUND if @force is %false and at least one
 * single-instance stream referenced by the inode was missing.
 */
int
inode_resolve_streams(struct wim_inode *inode, struct wim_lookup_table *table,
                      bool force)
{
        const u8 *hash;
        struct wim_lookup_table_entry *lte, *ads_lte;

        if (inode->i_resolved)
                return 0;

        struct wim_lookup_table_entry *ads_ltes[inode->i_num_ads];

        /* Resolve the default data stream */
        lte = NULL;
        hash = inode->i_hash;
        if (!is_zero_hash(hash)) {
                lte = lookup_stream(table, hash);
                if (!lte) {
                        if (force) {
                                lte = new_lookup_table_entry();
                                if (!lte)
                                        return WIMLIB_ERR_NOMEM;
                                copy_hash(lte->hash, hash);
                                lookup_table_insert(table, lte);
                        } else {
                                goto stream_not_found;
                        }
                }
        }

        /* Resolve the alternate data streams */
        for (u16 i = 0; i < inode->i_num_ads; i++) {
                struct wim_ads_entry *cur_entry;

                ads_lte = NULL;
                cur_entry = &inode->i_ads_entries[i];
                hash = cur_entry->hash;
                if (!is_zero_hash(hash)) {
                        ads_lte = lookup_stream(table, hash);
                        if (!ads_lte) {
                                if (force) {
                                        ads_lte = new_lookup_table_entry();
                                        if (!ads_lte)
                                                return WIMLIB_ERR_NOMEM;
                                        copy_hash(ads_lte->hash, hash);
                                        lookup_table_insert(table, ads_lte);
                                } else {
                                        goto stream_not_found;
                                }
                        }
                }
                ads_ltes[i] = ads_lte;
        }
        inode->i_lte = lte;
        for (u16 i = 0; i < inode->i_num_ads; i++)
                inode->i_ads_entries[i].lte = ads_ltes[i];
        inode->i_resolved = 1;
        return 0;

stream_not_found:
        return stream_not_found_error(inode, hash);
}

/*
 * Undo the effects of inode_resolve_streams().
 *
 * If the inode is not resolved, this function does nothing.
 */
void
inode_unresolve_streams(struct wim_inode *inode)
{
        if (!inode->i_resolved)
                return;

        if (inode->i_lte)
                copy_hash(inode->i_hash, inode->i_lte->hash);
        else
                zero_out_hash(inode->i_hash);

        for (u16 i = 0; i < inode->i_num_ads; i++) {
                if (inode->i_ads_entries[i].lte)
                        copy_hash(inode->i_ads_entries[i].hash,
                                  inode->i_ads_entries[i].lte->hash);
                else
                        zero_out_hash(inode->i_ads_entries[i].hash);
        }
        inode->i_resolved = 0;
}

int
stream_not_found_error(const struct wim_inode *inode, const u8 *hash)
{
        if (wimlib_print_errors) {
                tchar hashstr[SHA1_HASH_SIZE * 2 + 1];

                sprint_hash(hash, hashstr);

                ERROR("\"%"TS"\": stream not found\n"
                      "        SHA-1 message digest of missing stream:\n"
                      "        %"TS"",
                      inode_first_full_path(inode), hashstr);
        }
        return WIMLIB_ERR_RESOURCE_NOT_FOUND;
}

/*
 * Return the lookup table entry for stream @stream_idx of the inode, where
 * stream_idx = 0 means the default un-named file stream, and stream_idx >= 1
 * corresponds to an alternate data stream.
 *
 * This works for both resolved and un-resolved inodes.
 */
struct wim_lookup_table_entry *
inode_stream_lte(const struct wim_inode *inode, unsigned stream_idx,
                 const struct wim_lookup_table *table)
{
        if (inode->i_resolved)
                return inode_stream_lte_resolved(inode, stream_idx);
        else
                return inode_stream_lte_unresolved(inode, stream_idx, table);
}

/*
 * Return the lookup table entry for the unnamed data stream of a *resolved*
 * inode, or NULL if there is none.  Also return the 0-based index of the
 * corresponding stream in *stream_idx_ret.
 */
struct wim_lookup_table_entry *
inode_unnamed_stream_resolved(const struct wim_inode *inode, u16 *stream_idx_ret)
{
        wimlib_assert(inode->i_resolved);
        for (unsigned i = 0; i <= inode->i_num_ads; i++) {
                if (inode_stream_name_nbytes(inode, i) == 0 &&
                    !is_zero_hash(inode_stream_hash_resolved(inode, i)))
                {
                        *stream_idx_ret = i;
                        return inode_stream_lte_resolved(inode, i);
                }
        }
        *stream_idx_ret = 0;
        return NULL;
}

/*
 * Return the lookup table entry for the unnamed data stream of a *resolved*
 * inode, or NULL if there is none.
 */
struct wim_lookup_table_entry *
inode_unnamed_lte_resolved(const struct wim_inode *inode)
{
        u16 stream_idx;
        return inode_unnamed_stream_resolved(inode, &stream_idx);
}

/*
 * Return the lookup table entry for the unnamed data stream of an *unresolved*
 * inode, or NULL if there is none.
 */
struct wim_lookup_table_entry *
inode_unnamed_lte_unresolved(const struct wim_inode *inode,
                             const struct wim_lookup_table *table)
{
        wimlib_assert(!inode->i_resolved);
        for (unsigned i = 0; i <= inode->i_num_ads; i++) {
                if (inode_stream_name_nbytes(inode, i) == 0 &&
                    !is_zero_hash(inode_stream_hash_unresolved(inode, i)))
                {
                        return inode_stream_lte_unresolved(inode, i, table);
                }
        }
        return NULL;
}

/*
 * Return the lookup table entry for the unnamed data stream of an inode, or
 * NULL if there is none.
 *
 * You'd think this would be easier than it actually is, since the unnamed data
 * stream should be the one referenced from the inode itself.  Alas, if there
 * are named data streams, Microsoft's "imagex.exe" program will put the unnamed
 * data stream in one of the alternate data streams instead of inside the WIM
 * dentry itself.  So we need to check the alternate data streams too.
 *
 * Also, note that a dentry may appear to have more than one unnamed stream, but
 * if the SHA-1 message digest is all 0's then the corresponding stream does not
 * really "count" (this is the case for the inode's own file stream when the
 * file stream that should be there is actually in one of the alternate stream
 * entries.).  This is despite the fact that we may need to extract such a
 * missing entry as an empty file or empty named data stream.
 */
struct wim_lookup_table_entry *
inode_unnamed_lte(const struct wim_inode *inode,
                  const struct wim_lookup_table *table)
{
        if (inode->i_resolved)
                return inode_unnamed_lte_resolved(inode);
        else
                return inode_unnamed_lte_unresolved(inode, table);
}

/*
 * Return the SHA-1 message digest of the unnamed data stream of a WIM inode.
 *
 * If inode does not have an unnamed data stream, this returns a void SHA-1
 * message digest containing all zero bytes.
 */
const u8 *
inode_unnamed_stream_hash(const struct wim_inode *inode)
{
        const u8 *hash;

        for (unsigned i = 0; i <= inode->i_num_ads; i++) {
                if (inode_stream_name_nbytes(inode, i) == 0) {
                        hash = inode_stream_hash(inode, i);
                        if (!is_zero_hash(hash))
                                return hash;
                }
        }
        return zero_hash;
}

/*
 * Translate a single-instance stream entry into the pointer contained in the
 * inode (or ads entry of an inode) that references it.
 *
 * This is only possible for "unhashed" streams, which are guaranteed to have
 * only one reference, and that reference is guaranteed to be in a resolved
 * inode.  (It can't be in an unresolved inode, since that would imply the hash
 * is known!)
 */
struct wim_lookup_table_entry **
retrieve_lte_pointer(struct wim_lookup_table_entry *lte)
{
        wimlib_assert(lte->unhashed);
        struct wim_inode *inode = lte->back_inode;
        u32 stream_id = lte->back_stream_id;
        if (stream_id == 0)
                return &inode->i_lte;
        else
                for (u16 i = 0; i < inode->i_num_ads; i++)
                        if (inode->i_ads_entries[i].stream_id == stream_id)
                                return &inode->i_ads_entries[i].lte;
        wimlib_assert(0);
        return NULL;
}

/*
 * Read 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.
 *
 * @nbytes_remaining_p:
 *      Number of bytes of data remaining in the buffer pointed to by @p.
 *      On success this will be updated to point just past the ADS entries.
 *
 * 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.
 *
 * Return values:
 *      WIMLIB_ERR_SUCCESS (0)
 *      WIMLIB_ERR_INVALID_METADATA_RESOURCE
 *      WIMLIB_ERR_NOMEM
 */
int
read_ads_entries(const u8 * restrict p, struct wim_inode * restrict inode,
                 size_t *nbytes_remaining_p)
{
        size_t nbytes_remaining = *nbytes_remaining_p;
        u16 num_ads;
        struct wim_ads_entry *ads_entries;
        int ret;

        BUILD_BUG_ON(sizeof(struct wim_ads_entry_on_disk) != WIM_ADS_ENTRY_DISK_SIZE);

        /* 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 = utf16le_dupz(disk_entry->stream_name,
                                                              cur_entry->stream_name_nbytes);
                        if (!cur_entry->stream_name)
                                goto out_of_memory;
                } else {
                        /* Mark inode as having weird stream entries.  */
                        inode->i_canonical_streams = 0;
                }

                /* 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) & ~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;
        *nbytes_remaining_p = nbytes_remaining;
        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_METADATA_RESOURCE;
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;
}

/* Check a WIM inode for unusual field values.  */
void
check_inode(struct wim_inode *inode, const struct wim_security_data *sd)
{
        /* Check the security ID.  -1 is valid and means "no security
         * descriptor".  Anything else has to be a valid index into the WIM
         * image's security descriptors table. */
        if (inode->i_security_id < -1 ||
            (inode->i_security_id >= 0 &&
             inode->i_security_id >= sd->num_entries))
        {
                WARNING("\"%"TS"\" has an invalid security ID (%d)",
                        inode_first_full_path(inode), inode->i_security_id);
                inode->i_security_id = -1;
        }

        /* Make sure there is only one unnamed data stream. */
        unsigned num_unnamed_streams = 0;
        for (unsigned i = 0; i <= inode->i_num_ads; i++) {
                const u8 *hash;
                hash = inode_stream_hash(inode, i);
                if (inode_stream_name_nbytes(inode, i) == 0 && !is_zero_hash(hash))
                        num_unnamed_streams++;
        }
        if (num_unnamed_streams > 1) {
                WARNING("\"%"TS"\" has multiple (%u) un-named streams",
                        inode_first_full_path(inode), num_unnamed_streams);
                /* We currently don't treat this as an error and will just end
                 * up using the first unnamed data stream in the inode.  */
        }
}

/* Acquire another reference to each single-instance stream referenced by this
 * inode.  This is necessary when creating a hard link to this inode.
 *
 * The inode must be resolved.  */
void
inode_ref_streams(struct wim_inode *inode)
{
        for (unsigned i = 0; i <= inode->i_num_ads; i++) {
                struct wim_lookup_table_entry *lte;

                lte = inode_stream_lte_resolved(inode, i);
                if (lte)
                        lte->refcnt++;
        }
}

/* Drop a reference to each single-instance stream referenced by this inode.
 * This is necessary when deleting a hard link to this inode.  */
void
inode_unref_streams(struct wim_inode *inode,
                    struct wim_lookup_table *lookup_table)
{
        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);
        }
}

/* Initialize a hash table for hard link detection.  */
int
init_inode_table(struct wim_inode_table *table, size_t capacity)
{
        table->array = CALLOC(capacity, sizeof(table->array[0]));
        if (!table->array)
                return WIMLIB_ERR_NOMEM;
        table->num_entries  = 0;
        table->capacity  = capacity;
        INIT_LIST_HEAD(&table->extra_inodes);
        return 0;
}

/* Free the memory allocated by init_inode_table().  */
void
destroy_inode_table(struct wim_inode_table *table)
{
        FREE(table->array);
}

static struct wim_inode *
inode_table_get_inode(struct wim_inode_table *table, u64 ino, u64 devno)
{
        u64 hash = hash_u64(hash_u64(ino) + hash_u64(devno));
        size_t pos = hash % table->capacity;
        struct wim_inode *inode;
        struct hlist_node *cur;

        /* Search for an existing inode having the same inode number and device
         * number.  */
        hlist_for_each_entry(inode, cur, &table->array[pos], i_hlist) {
                if (inode->i_ino == ino && inode->i_devno == devno) {
                        /* Found; use the existing inode.  */
                        inode->i_nlink++;
                        return inode;
                }
        }

        /* Create a new inode and insert it into the table.  */
        inode = new_timeless_inode();
        if (inode) {
                inode->i_ino = ino;
                inode->i_devno = devno;
                hlist_add_head(&inode->i_hlist, &table->array[pos]);
                table->num_entries++;
        }
        return inode;
}

/*
 * Allocate a new dentry, with hard link detection.
 *
 * @table
 *      The inode table being used for the current directory scan operation.  It
 *      will contain the mapping from (ino, devno) pairs to inodes.
 *
 * @name
 *      The name to give the new dentry.
 *
 * @ino
 *      The inode number of the file, read from the filesystem.
 *
 * @devno
 *      The device number of the file, read from the filesystem.  Proper setting
 *      of this parameter prevents cross-device hardlinks from being created.
 *      If this is not a problem (perhaps because the current directory scan
 *      operation is guaranteed to never traverse a filesystem boundary), then
 *      this parameter can just be a fixed value such as 0.
 *
 * @noshare
 *      If %true, the new dentry will not be hard linked to any existing inode,
 *      regardless of the values of @ino and @devno.  If %false, normal hard
 *      link detection will be done.
 *
 * @dentry_ret
 *      On success, a pointer to the new dentry will be returned in this
 *      location.  If i_nlink of the dentry's inode is greater than 1, then this
 *      function created a hard link to an existing inode rather than creating a
 *      new inode.
 *
 * On success, returns 0.  On failure, returns WIMLIB_ERR_NOMEM or an error code
 * resulting from a failed string conversion.
 */
int
inode_table_new_dentry(struct wim_inode_table *table, const tchar *name,
                       u64 ino, u64 devno, bool noshare,
                       struct wim_dentry **dentry_ret)
{
        struct wim_dentry *dentry;
        struct wim_inode *inode;
        int ret;

        if (noshare) {
                /* File that cannot be hardlinked--- Return a new inode with its
                 * inode and device numbers left at 0. */
                ret = new_dentry_with_timeless_inode(name, &dentry);
                if (ret)
                        return ret;
                list_add_tail(&dentry->d_inode->i_list, &table->extra_inodes);
        } else {
                /* File that can be hardlinked--- search the table for an
                 * existing inode matching the inode number and device;
                 * otherwise create a new inode. */
                ret = new_dentry(name, &dentry);
                if (ret)
                        return ret;
                inode = inode_table_get_inode(table, ino, devno);
                if (!inode) {
                        free_dentry(dentry);
                        return WIMLIB_ERR_NOMEM;
                }
                /* If using an existing inode, we need to gain a reference to
                 * each of its streams. */
                if (inode->i_nlink > 1)
                        inode_ref_streams(inode);
                dentry->d_inode = inode;
                inode_add_dentry(dentry, inode);
        }
        *dentry_ret = dentry;
        return 0;
}



/*
 * Following the allocation of dentries with hard link detection using
 * inode_table_new_dentry(), this function will assign consecutive inode numbers
 * to the new set of inodes.  It will also append the list of new inodes to the
 * list @head, which must contain any inodes already existing in the WIM image.
 */
void
inode_table_prepare_inode_list(struct wim_inode_table *table,
                               struct list_head *head)
{
        struct wim_inode *inode, *tmp_inode;
        struct hlist_node *cur, *tmp;
        u64 cur_ino = 1;

        /* Re-assign inode numbers in the existing list to avoid duplicates. */
        list_for_each_entry(inode, head, i_list)
                inode->i_ino = cur_ino++;

        /* Assign inode numbers to the new inodes and move them to the image's
         * inode list. */
        for (size_t i = 0; i < table->capacity; i++) {
                hlist_for_each_entry_safe(inode, cur, tmp, &table->array[i], i_hlist)
                {
                        inode->i_ino = cur_ino++;
                        inode->i_devno = 0;
                        list_add_tail(&inode->i_list, head);
                }
                INIT_HLIST_HEAD(&table->array[i]);
        }
        list_for_each_entry_safe(inode, tmp_inode, &table->extra_inodes, i_list)
        {
                inode->i_ino = cur_ino++;
                inode->i_devno = 0;
                list_add_tail(&inode->i_list, head);
        }
        INIT_LIST_HEAD(&table->extra_inodes);
        table->num_entries = 0;
}