]> wimlib.net Git - wimlib/blobdiff - src/resource.c
Calculate SHA1 md of NTFS reparse points correctly
[wimlib] / src / resource.c
index 4f093622f9e64d356484015f8b45db1cc33635b9..51bde70822c7ab33e5341ef33fdb63cd0e64fa83 100644 (file)
@@ -5,47 +5,56 @@
  */
 
 /*
- * Copyright (C) 2010 Carl Thijssen
  * Copyright (C) 2012 Eric Biggers
  *
  * This file is part of wimlib, a library for working with WIM files.
  *
  * wimlib is free software; you can redistribute it and/or modify it under the
- * terms of the GNU Lesser General Public License as published by the Free
- * Software Foundation; either version 2.1 of the License, or (at your option)
- * any later version.
+ * 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 Lesser General Public License for more
- * details.
+ * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
  *
- * You should have received a copy of the GNU Lesser General Public License
- * along with wimlib; if not, see http://www.gnu.org/licenses/.
+ * You should have received a copy of the GNU General Public License along with
+ * wimlib; if not, see http://www.gnu.org/licenses/.
  */
 
+#include "config.h"
+
+#include <stdlib.h>
+#include <stdarg.h>
+
+#include "dentry.h"
+
 #include "wimlib_internal.h"
 #include "lookup_table.h"
 #include "io.h"
 #include "lzx.h"
 #include "xpress.h"
 #include "sha1.h"
-#include "dentry.h"
-#include "config.h"
 #include <unistd.h>
 #include <errno.h>
-#include <alloca.h>
 
+#ifdef WITH_NTFS_3G
+#include <time.h>
+#include <ntfs-3g/attrib.h>
+#include <ntfs-3g/inode.h>
+#include <ntfs-3g/dir.h>
+#endif
 
-/* 
+
+/*
  * Reads all or part of a compressed resource into an in-memory buffer.
  *
  * @fp:                The FILE* for the WIM file.
- * @resource_compressed_size:           The compressed size of the resource.  
+ * @resource_compressed_size:           The compressed size of the resource.
  * @resource_uncompressed_size:  The uncompressed size of the resource.
  * @resource_offset:            The offset of the start of the resource from
  *                                     the start of the stream @fp.
- * @resource_ctype:    The compression type of the resource. 
+ * @resource_ctype:    The compression type of the resource.
  * @len:               The number of bytes of uncompressed data to read from
  *                             the resource.
  * @offset:            The offset of the bytes to read within the uncompressed
@@ -55,9 +64,9 @@
  *
  * Returns zero on success, nonzero on failure.
  */
-static int read_compressed_resource(FILE *fp, u64 resource_compressed_size, 
-                                   u64 resource_uncompressed_size, 
-                                   u64 resource_offset, int resource_ctype, 
+static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
+                                   u64 resource_uncompressed_size,
+                                   u64 resource_offset, int resource_ctype,
                                    u64 len, u64 offset, u8  contents_ret[])
 {
 
@@ -88,7 +97,7 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
         * The chunk offsets are measured relative to the end of the chunk
         * table.  The first chunk is omitted from the table in the WIM file
         * because its offset is implicitly given by the fact that it directly
-        * follows the chunk table and therefore must have an offset of 0. 
+        * follows the chunk table and therefore must have an offset of 0.
         */
 
        /* Calculate how many chunks the resource conists of in its entirety. */
@@ -136,7 +145,7 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
        /* According to M$'s documentation, if the uncompressed size of
         * the file is greater than 4 GB, the chunk entries are 8-byte
         * integers.  Otherwise, they are 4-byte integers. */
-       u64 chunk_entry_size = (resource_uncompressed_size >= (u64)1 << 32) ? 
+       u64 chunk_entry_size = (resource_uncompressed_size >= (u64)1 << 32) ?
                                                                        8 : 4;
 
        /* Size of the full chunk table in the WIM file. */
@@ -150,11 +159,11 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
 
        /* Number of entries we need to actually read from the chunk
         * table (excludes the implicit first chunk). */
-       u64 num_needed_chunk_entries = (start_chunk == 0) ? 
+       u64 num_needed_chunk_entries = (start_chunk == 0) ?
                                num_needed_chunks - 1 : num_needed_chunks;
 
        /* Skip over unneeded chunk table entries. */
-       u64 file_offset_of_needed_chunk_entries = resource_offset + 
+       u64 file_offset_of_needed_chunk_entries = resource_offset +
                                start_table_idx * chunk_entry_size;
        if (fseeko(fp, file_offset_of_needed_chunk_entries, SEEK_SET) != 0) {
                ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" to read "
@@ -181,17 +190,17 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
        if (chunk_entry_size == 4) {
                u32 *entries = (u32*)chunk_tab_buf;
                while (num_needed_chunk_entries--)
-                       *chunk_tab_p++ = to_le32(*entries++);
+                       *chunk_tab_p++ = le32_to_cpu(*entries++);
        } else {
                u64 *entries = (u64*)chunk_tab_buf;
                while (num_needed_chunk_entries--)
-                       *chunk_tab_p++ = to_le64(*entries++);
+                       *chunk_tab_p++ = le64_to_cpu(*entries++);
        }
 
        /* Done with the chunk table now.  We must now seek to the first chunk
         * that is needed for the read. */
 
-       u64 file_offset_of_first_needed_chunk = resource_offset + 
+       u64 file_offset_of_first_needed_chunk = resource_offset +
                                chunk_table_size + chunk_offsets[0];
        if (fseeko(fp, file_offset_of_first_needed_chunk, SEEK_SET) != 0) {
                ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" to read "
@@ -227,7 +236,7 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
                         * expand to WIM_CHUNK_SIZE uncompressed, and the amount
                         * of compressed data for the chunk is given by the
                         * difference of offsets in the chunk offset table. */
-                       compressed_chunk_size = chunk_offsets[i + 1 - start_chunk] - 
+                       compressed_chunk_size = chunk_offsets[i + 1 - start_chunk] -
                                                chunk_offsets[i - start_chunk];
                        uncompressed_chunk_size = WIM_CHUNK_SIZE;
                } else {
@@ -235,15 +244,15 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
                         * bytes in the file resource, and the last uncompressed
                         * chunk has size equal to however many bytes are left-
                         * that is, the remainder of the uncompressed size when
-                        * divided by WIM_CHUNK_SIZE. 
+                        * divided by WIM_CHUNK_SIZE.
                         *
                         * Note that the resource_compressed_size includes the
                         * chunk table, so the size of it must be subtracted. */
-                       compressed_chunk_size = resource_compressed_size - 
+                       compressed_chunk_size = resource_compressed_size -
                                                chunk_table_size -
                                                chunk_offsets[i - start_chunk];
 
-                       uncompressed_chunk_size = resource_uncompressed_size % 
+                       uncompressed_chunk_size = resource_uncompressed_size %
                                                                WIM_CHUNK_SIZE;
 
                        /* If the remainder is 0, the last chunk actually
@@ -270,7 +279,7 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
                        end_offset = WIM_CHUNK_SIZE - 1;
 
                u64 partial_chunk_size = end_offset + 1 - start_offset;
-               bool is_partial_chunk = (partial_chunk_size != 
+               bool is_partial_chunk = (partial_chunk_size !=
                                                uncompressed_chunk_size);
 
                DEBUG2("start_offset = %u, end_offset = %u", start_offset,
@@ -290,7 +299,7 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
                                        return WIMLIB_ERR_READ;
                                }
                        }
-                       if (fread(out_p, 1, partial_chunk_size, fp) != 
+                       if (fread(out_p, 1, partial_chunk_size, fp) !=
                                        partial_chunk_size)
                                goto err;
                } else {
@@ -298,7 +307,7 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
                        int ret;
 
                        /* Read the compressed data into compressed_buf. */
-                       if (fread(compressed_buf, 1, compressed_chunk_size, 
+                       if (fread(compressed_buf, 1, compressed_chunk_size,
                                                fp) != compressed_chunk_size)
                                goto err;
 
@@ -309,7 +318,7 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
 
                                ret = decompress(compressed_buf,
                                                compressed_chunk_size,
-                                               uncompressed_buf, 
+                                               uncompressed_buf,
                                                uncompressed_chunk_size);
                                if (ret != 0)
                                        return WIMLIB_ERR_DECOMPRESSION;
@@ -340,7 +349,7 @@ err:
        return WIMLIB_ERR_READ;
 }
 
-/* 
+/*
  * Reads uncompressed data from an open file stream.
  */
 int read_uncompressed_resource(FILE *fp, u64 offset, u64 len,
@@ -380,8 +389,21 @@ const u8 *get_resource_entry(const u8 *p, struct resource_entry *entry)
        p = get_u8(p, &flags);
        entry->size = size;
        entry->flags = flags;
+
+       /* offset and original_size are truncated to 62 bits to avoid possible
+        * overflows, when converting to a signed 64-bit integer (off_t) or when
+        * adding size or original_size.  This is okay since no one would ever
+        * actually have a WIM bigger than 4611686018427387903 bytes... */
        p = get_u64(p, &entry->offset);
+       if (entry->offset & 0xc000000000000000ULL) {
+               WARNING("Truncating offset in resource entry");
+               entry->offset &= 0x3fffffffffffffffULL;
+       }
        p = get_u64(p, &entry->original_size);
+       if (entry->original_size & 0xc000000000000000ULL) {
+               WARNING("Truncating original_size in resource entry");
+               entry->original_size &= 0x3fffffffffffffffULL;
+       }
        return p;
 }
 
@@ -397,6 +419,59 @@ u8 *put_resource_entry(u8 *p, const struct resource_entry *entry)
        return p;
 }
 
+#ifdef WITH_FUSE
+static FILE *wim_get_fp(WIMStruct *w)
+{
+       pthread_mutex_lock(&w->fp_tab_mutex);
+       FILE *fp;
+
+       wimlib_assert(w->filename != NULL);
+
+       for (size_t i = 0; i < w->num_allocated_fps; i++) {
+               if (w->fp_tab[i]) {
+                       fp = w->fp_tab[i];
+                       w->fp_tab[i] = NULL;
+                       goto out;
+               }
+       }
+       DEBUG("Opening extra file descriptor to `%s'", w->filename);
+       fp = fopen(w->filename, "rb");
+       if (!fp)
+               ERROR_WITH_ERRNO("Failed to open `%s'", w->filename);
+out:
+       pthread_mutex_unlock(&w->fp_tab_mutex);
+       return fp;
+}
+
+static int wim_release_fp(WIMStruct *w, FILE *fp)
+{
+       int ret = 0;
+       FILE **fp_tab;
+
+       pthread_mutex_lock(&w->fp_tab_mutex);
+
+       for (size_t i = 0; i < w->num_allocated_fps; i++) {
+               if (w->fp_tab[i] == NULL) {
+                       w->fp_tab[i] = fp;
+                       goto out;
+               }
+       }
+
+       fp_tab = REALLOC(w->fp_tab, sizeof(FILE*) * (w->num_allocated_fps + 4));
+       if (!fp_tab) {
+               ret = WIMLIB_ERR_NOMEM;
+               goto out;
+       }
+       w->fp_tab = fp_tab;
+       memset(&w->fp_tab[w->num_allocated_fps], 0, 4 * sizeof(FILE*));
+       w->fp_tab[w->num_allocated_fps] = fp;
+       w->num_allocated_fps += 4;
+out:
+       pthread_mutex_unlock(&w->fp_tab_mutex);
+       return ret;
+}
+#endif
+
 /*
  * Reads some data from the resource corresponding to a WIM lookup table entry.
  *
@@ -404,68 +479,74 @@ u8 *put_resource_entry(u8 *p, const struct resource_entry *entry)
  * @buf:       Buffer into which to write the data.
  * @size:      Number of bytes to read.
  * @offset:    Offset at which to start reading the resource.
- * @raw:       If %true, compressed data is read literally rather than being
- *                     decompressed first.
  *
  * Returns zero on success, nonzero on failure.
  */
 int read_wim_resource(const struct lookup_table_entry *lte, u8 buf[],
-                     size_t size, u64 offset, bool raw)
+                     size_t size, u64 offset, int flags)
 {
+       int ctype;
+       int ret = 0;
+       FILE *fp;
+
        /* We shouldn't be allowing read over-runs in any part of the library.
         * */
-       if (raw)
+       if (flags & WIMLIB_RESOURCE_FLAG_RAW)
                wimlib_assert(offset + size <= lte->resource_entry.size);
        else
                wimlib_assert(offset + size <= lte->resource_entry.original_size);
 
-       int ctype;
-       int ret;
-       FILE *fp;
        switch (lte->resource_location) {
        case RESOURCE_IN_WIM:
                /* The resource is in a WIM file, and its WIMStruct is given by
                 * the lte->wim member.  The resource may be either compressed
                 * or uncompressed. */
-               wimlib_assert(lte->wim);
-               wimlib_assert(lte->wim->fp);
+               wimlib_assert(lte->wim != NULL);
+
+               #ifdef WITH_FUSE
+               if (flags & WIMLIB_RESOURCE_FLAG_MULTITHREADED) {
+                       fp = wim_get_fp(lte->wim);
+                       if (!fp)
+                               return WIMLIB_ERR_OPEN;
+               } else
+               #endif
+               {
+                       wimlib_assert(!(flags & WIMLIB_RESOURCE_FLAG_MULTITHREADED));
+                       wimlib_assert(lte->wim->fp != NULL);
+                       fp = lte->wim->fp;
+               }
+
                ctype = wim_resource_compression_type(lte);
 
-               /* XXX This check should be moved elsewhere */
-               if (ctype == WIM_COMPRESSION_TYPE_NONE &&
-                    lte->resource_entry.original_size !=
-                     lte->resource_entry.size) {
-                       ERROR("WIM resource at offset %"PRIu64", size %"PRIu64
-                             "has an original size of %"PRIu64", but is "
-                             "uncompressed",
-                             lte->resource_entry.offset,
-                             lte->resource_entry.size,
-                             lte->resource_entry.original_size);
-                       return WIMLIB_ERR_INVALID_RESOURCE_SIZE;
-               }
+               wimlib_assert(ctype != WIM_COMPRESSION_TYPE_NONE ||
+                             (lte->resource_entry.original_size ==
+                              lte->resource_entry.size));
 
-               if (raw || ctype == WIM_COMPRESSION_TYPE_NONE)
-                       return read_uncompressed_resource(lte->wim->fp,
-                                                         lte->resource_entry.offset + offset,
-                                                         size, buf);
+               if ((flags & WIMLIB_RESOURCE_FLAG_RAW)
+                   || ctype == WIM_COMPRESSION_TYPE_NONE)
+                       ret = read_uncompressed_resource(fp,
+                                                        lte->resource_entry.offset + offset,
+                                                        size, buf);
                else
-                       return read_compressed_resource(lte->wim->fp,
-                                                       lte->resource_entry.size,
-                                                       lte->resource_entry.original_size,
-                                                       lte->resource_entry.offset,
-                                                       ctype, size, offset, buf);
+                       ret = read_compressed_resource(fp,
+                                                      lte->resource_entry.size,
+                                                      lte->resource_entry.original_size,
+                                                      lte->resource_entry.offset,
+                                                      ctype, size, offset, buf);
+       #ifdef WITH_FUSE
+               if (flags & WIMLIB_RESOURCE_FLAG_MULTITHREADED) {
+                       int ret2 = wim_release_fp(lte->wim, fp);
+                       if (ret == 0)
+                               ret = ret2;
+               }
+       #endif
                break;
        case RESOURCE_IN_STAGING_FILE:
-               /* The WIM FUSE implementation needs to handle multiple open
-                * file descriptors per lookup table entry so it does not
-                * currently work with this function. */
-               wimlib_assert(lte->staging_file_name);
-               wimlib_assert(0);
-               break;
        case RESOURCE_IN_FILE_ON_DISK:
                /* The resource is in some file on the external filesystem and
                 * needs to be read uncompressed */
                wimlib_assert(lte->file_on_disk);
+               wimlib_assert(&lte->file_on_disk == &lte->staging_file_name);
                /* Use existing file pointer if available; otherwise open one
                 * temporarily */
                if (lte->file_on_disk_fp) {
@@ -475,26 +556,43 @@ int read_wim_resource(const struct lookup_table_entry *lte, u8 buf[],
                        if (!fp) {
                                ERROR_WITH_ERRNO("Failed to open the file "
                                                 "`%s'", lte->file_on_disk);
+                               ret = WIMLIB_ERR_OPEN;
+                               break;
                        }
                }
                ret = read_uncompressed_resource(fp, offset, size, buf);
                if (fp != lte->file_on_disk_fp)
                        fclose(fp);
-               return ret;
                break;
        case RESOURCE_IN_ATTACHED_BUFFER:
                /* The resource is directly attached uncompressed in an
                 * in-memory buffer. */
-               wimlib_assert(lte->attached_buffer);
+               wimlib_assert(lte->attached_buffer != NULL);
                memcpy(buf, lte->attached_buffer + offset, size);
-               return 0;
                break;
+#ifdef WITH_NTFS_3G
+       case RESOURCE_IN_NTFS_VOLUME:
+               wimlib_assert(lte->ntfs_loc != NULL);
+               wimlib_assert(lte->attr != NULL);
+               if (lte->ntfs_loc->is_reparse_point)
+                       offset += 8;
+               if (ntfs_attr_pread(lte->attr, offset, size, buf) != size) {
+                       ERROR_WITH_ERRNO("Error reading NTFS attribute "
+                                        "at `%s'",
+                                        lte->ntfs_loc->path_utf8);
+                       ret = WIMLIB_ERR_NTFS_3G;
+               }
+               break;
+#endif
        default:
-               assert(0);
+               wimlib_assert(0);
+               ret = -1;
+               break;
        }
+       return ret;
 }
 
-/* 
+/*
  * Reads all the data from the resource corresponding to a WIM lookup table
  * entry.
  *
@@ -504,394 +602,10 @@ int read_wim_resource(const struct lookup_table_entry *lte, u8 buf[],
  *
  * Returns 0 on success; nonzero on failure.
  */
-int read_full_wim_resource(const struct lookup_table_entry *lte, u8 buf[])
-{
-       return read_wim_resource(lte, buf, wim_resource_size(lte), 0, false);
-}
-
-/* Chunk table that's located at the beginning of each compressed resource in
- * the WIM.  (This is not the on-disk format; the on-disk format just has an
- * array of offsets.) */
-struct chunk_table {
-       off_t file_offset;
-       u64 num_chunks;
-       u64 original_resource_size;
-       u64 bytes_per_chunk_entry;
-       u64 table_disk_size;
-       u64 cur_offset;
-       u64 *cur_offset_p;
-       u64 offsets[0];
-};
-
-/* 
- * Allocates and initializes a chunk table, and reserves space for it in the
- * output file.
- */
-static int
-begin_wim_resource_chunk_tab(const struct lookup_table_entry *lte,
-                            FILE *out_fp,
-                            off_t file_offset,
-                            struct chunk_table **chunk_tab_ret)
-{
-       u64 size = wim_resource_size(lte);
-       u64 num_chunks = (size + WIM_CHUNK_SIZE - 1) / WIM_CHUNK_SIZE;
-       struct chunk_table *chunk_tab = MALLOC(sizeof(struct chunk_table) +
-                                              num_chunks * sizeof(u64));
-       int ret = 0;
-
-       wimlib_assert(size != 0);
-
-       if (!chunk_tab) {
-               ERROR("Failed to allocate chunk table for %"PRIu64" byte "
-                     "resource", size);
-               ret = WIMLIB_ERR_NOMEM;
-               goto out;
-       }
-       chunk_tab->file_offset = file_offset;
-       chunk_tab->num_chunks = num_chunks;
-       chunk_tab->original_resource_size = size;
-       chunk_tab->bytes_per_chunk_entry = (size >= (1ULL << 32)) ? 8 : 4;
-       chunk_tab->table_disk_size = chunk_tab->bytes_per_chunk_entry *
-                                    (num_chunks - 1);
-       chunk_tab->cur_offset = 0;
-       chunk_tab->cur_offset_p = chunk_tab->offsets;
-
-       if (fwrite(chunk_tab, 1, chunk_tab->table_disk_size, out_fp) !=
-                  chunk_tab->table_disk_size) {
-               ERROR_WITH_ERRNO("Failed to write chunk table in compressed "
-                                "file resource");
-               ret = WIMLIB_ERR_WRITE;
-               goto out;
-       }
-
-       *chunk_tab_ret = chunk_tab;
-out:
-       return ret;
-}
-
-/* 
- * Compresses a chunk of a WIM resource.
- *
- * @chunk:             Uncompressed data of the chunk.
- * @chunk_size:                Size of the uncompressed chunk in bytes.
- * @compressed_chunk:  Pointer to output buffer of size at least
- *                             (@chunk_size - 1) bytes.
- * @compressed_chunk_len_ret:  Pointer to an unsigned int into which the size
- *                                     of the compressed chunk will be
- *                                     returned.
- * @ctype:     Type of compression to use.  Must be WIM_COMPRESSION_TYPE_LZX
- *             or WIM_COMPRESSION_TYPE_XPRESS.
- *
- * Returns zero if compressed succeeded, and nonzero if the chunk could not be
- * compressed to any smaller than @chunk_size.  This function cannot fail for
- * any other reasons.
- */
-static int compress_chunk(const u8 chunk[], unsigned chunk_size,
-                         u8 compressed_chunk[],
-                         unsigned *compressed_chunk_len_ret,
-                         int ctype)
-{
-       unsigned compressed_chunk_sz;
-       int (*compress)(const void *, unsigned, void *, unsigned *);
-       switch (ctype) {
-       case WIM_COMPRESSION_TYPE_LZX:
-               compress = lzx_compress;
-               break;
-       case WIM_COMPRESSION_TYPE_XPRESS:
-               compress = xpress_compress;
-               break;
-       default:
-               wimlib_assert(0);
-               break;
-       }
-       return (*compress)(chunk, chunk_size, compressed_chunk,
-                          compressed_chunk_len_ret);
-}
-
-/*
- * Writes a chunk of a WIM resource to an output file.
- *
- * @chunk:       Uncompressed data of the chunk.
- * @chunk_size:          Size of the chunk (<= WIM_CHUNK_SIZE)
- * @out_fp:      FILE * to write tho chunk to.
- * @out_ctype:   Compression type to use when writing the chunk (ignored if no 
- *                     chunk table provided)
- * @chunk_tab:   Pointer to chunk table being created.  It is updated with the
- *                     offset of the chunk we write.
- *
- * Returns 0 on success; nonzero on failure.
- */
-static int write_wim_resource_chunk(const u8 chunk[], unsigned chunk_size,
-                                   FILE *out_fp, int out_ctype,
-                                   struct chunk_table *chunk_tab)
-{
-       const u8 *out_chunk;
-       unsigned out_chunk_size;
-
-       wimlib_assert(chunk_size <= WIM_CHUNK_SIZE);
-
-       if (!chunk_tab) {
-               out_chunk = chunk;
-               out_chunk_size = chunk_size;
-       } else {
-               u8 *compressed_chunk = alloca(chunk_size);
-               int ret;
-               unsigned compressed_chunk_len;
-
-               ret = compress_chunk(chunk, chunk_size, compressed_chunk,
-                                    &out_chunk_size, out_ctype);
-               if (ret == 0) {
-                       out_chunk = compressed_chunk;
-               } else {
-                       out_chunk = chunk;
-                       out_chunk_size = chunk_size;
-               }
-               *chunk_tab->cur_offset_p++ = chunk_tab->cur_offset;
-               chunk_tab->cur_offset += out_chunk_size;
-       }
-       
-       if (fwrite(out_chunk, 1, out_chunk_size, out_fp) != out_chunk_size) {
-               ERROR_WITH_ERRNO("Failed to write WIM resource chunk");
-               return WIMLIB_ERR_WRITE;
-       }
-       return 0;
-}
-
-/* 
- * Finishes a WIM chunk tale and writes it to the output file at the correct
- * offset.
- *
- * The final size of the full compressed resource is returned in the
- * @compressed_size_p.
- */
-static int
-finish_wim_resource_chunk_tab(struct chunk_table *chunk_tab,
-                             FILE *out_fp, u64 *compressed_size_p)
-{
-       size_t bytes_written;
-       if (fseeko(out_fp, chunk_tab->file_offset, SEEK_SET) != 0) {
-               ERROR_WITH_ERRNO("Failed to seek to byte "PRIu64" of output "
-                                "WIM file", chunk_tab->file_offset);
-               return WIMLIB_ERR_WRITE;
-       }
-
-       if (chunk_tab->bytes_per_chunk_entry == 8) {
-               array_to_le64(chunk_tab->offsets, chunk_tab->num_chunks);
-       } else {
-               for (u64 i = 0; i < chunk_tab->num_chunks; i++)
-                       ((u32*)chunk_tab->offsets)[i] =
-                               to_le32(chunk_tab->offsets[i]);
-       }
-       bytes_written = fwrite((u8*)chunk_tab->offsets +
-                                       chunk_tab->bytes_per_chunk_entry,
-                              1, chunk_tab->table_disk_size, out_fp);
-       if (bytes_written != chunk_tab->table_disk_size) {
-               ERROR_WITH_ERRNO("Failed to write chunk table in compressed "
-                                "file resource");
-               return WIMLIB_ERR_WRITE;
-       }
-       if (fseeko(out_fp, 0, SEEK_END) != 0) {
-               ERROR_WITH_ERRNO("Failed to seek to end of output WIM file");
-               return WIMLIB_ERR_WRITE;
-       }
-       *compressed_size_p = chunk_tab->cur_offset + chunk_tab->table_disk_size;
-       return 0;
-}
-
-/*
- * Writes a WIM resource to a FILE * opened for writing.  The resource may be
- * written uncompressed or compressed depending on the @out_ctype parameter.
- *
- * If by chance the resource compresses to more than the original size (this may
- * happen with random data or files than are pre-compressed), the resource is
- * instead written uncompressed (and this is reflected in the @out_res_entry by
- * removing the WIM_RESHDR_FLAG_COMPRESSED flag).
- *
- * @lte:       The lookup table entry for the WIM resource.
- * @out_fp:    The FILE * to write the resource to.
- * @out_ctype:  The compression type of the resource to write.  Note: if this is
- *                     the same as the compression type of the WIM resource we
- *                     need to read, we simply copy the data (i.e. we do not
- *                     uncompress it, then compress it again).
- * @out_res_entry:  If non-NULL, a resource entry that is filled in with the 
- *                 offset, original size, compressed size, and compression flag
- *                 of the output resource.
- *
- * Returns 0 on success; nonzero on failure.
- */
-static int write_wim_resource(struct lookup_table_entry *lte,
-                             FILE *out_fp, int out_ctype,
-                             struct resource_entry *out_res_entry)
+int read_full_wim_resource(const struct lookup_table_entry *lte, u8 buf[],
+                          int flags)
 {
-       u64 bytes_remaining;
-       u64 original_size;
-       u64 old_compressed_size;
-       u64 new_compressed_size;
-       u64 offset = 0;
-       int ret = 0;
-       struct chunk_table *chunk_tab = NULL;
-       bool raw;
-       off_t file_offset;
-
-       /* Original size of the resource */
-       original_size = wim_resource_size(lte);
-
-       /* Compressed size of the resource (as it exists now) */
-       old_compressed_size = wim_resource_compressed_size(lte);
-
-       /* Current offset in output file */
-       file_offset = ftello(out_fp);
-       if (file_offset == -1) {
-               ERROR_WITH_ERRNO("Failed to get offset in output "
-                                "stream");
-               return WIMLIB_ERR_WRITE;
-       }
-       
-       /* Are the compression types the same?  If so, do a raw copy (copy
-        * without decompressing and recompressing the data). */
-       raw = (wim_resource_compression_type(lte) == out_ctype
-              && out_ctype != WIM_COMPRESSION_TYPE_NONE);
-       if (raw)
-               bytes_remaining = old_compressed_size;
-       else
-               bytes_remaining = original_size;
-
-       /* Empty resource; nothing needs to be done, so just return success. */
-       if (bytes_remaining == 0)
-               return 0;
-
-       /* Buffer for reading chunks for the resource */
-       char buf[min(WIM_CHUNK_SIZE, bytes_remaining)];
-
-       /* If we are writing a compressed resource and not doing a raw copy, we
-        * need to initialize the chunk table */
-       if (out_ctype != WIM_COMPRESSION_TYPE_NONE && !raw) {
-               ret = begin_wim_resource_chunk_tab(lte, out_fp, file_offset,
-                                                  &chunk_tab);
-               if (ret != 0)
-                       goto out;
-       }
-
-       /* If the WIM resource is in an external file, open a FILE * to it so we
-        * don't have to open a temporary one in read_wim_resource() for each
-        * chunk. */
-       if (lte->resource_location == RESOURCE_IN_FILE_ON_DISK
-            && !lte->file_on_disk_fp)
-       {
-               wimlib_assert(lte->file_on_disk);
-               lte->file_on_disk_fp = fopen(lte->file_on_disk, "rb");
-               if (!lte->file_on_disk_fp) {
-                       ERROR_WITH_ERRNO("Failed to open the file `%s' for "
-                                        "reading", lte->file_on_disk);
-                       ret = WIMLIB_ERR_OPEN;
-                       goto out;
-               }
-       }
-
-       /* If we aren't doing a raw copy, we will compute the SHA1 message
-        * digest of the resource as we read it, and verify it's the same as the
-        * hash given in the lookup table entry once we've finished reading the
-        * resource. */
-       SHA_CTX ctx;
-       if (!raw)
-               sha1_init(&ctx);
-
-       /* While there are still bytes remaining in the WIM resource, read a
-        * chunk of the resource, update SHA1, then write that chunk using the
-        * desired compression type. */
-       do {
-               u64 to_read = min(bytes_remaining, WIM_CHUNK_SIZE);
-               ret = read_wim_resource(lte, buf, to_read, offset, raw);
-               if (ret != 0)
-                       goto out_fclose;
-               if (!raw)
-                       sha1_update(&ctx, buf, to_read);
-               ret = write_wim_resource_chunk(buf, to_read, out_fp,
-                                              out_ctype, chunk_tab);
-               if (ret != 0)
-                       goto out_fclose;
-               bytes_remaining -= to_read;
-               offset += to_read;
-       } while (bytes_remaining);
-
-       /* If writing a compressed resource and not doing a raw copy, write the
-        * chunk table, and finish_wim_resource_chunk_tab() will provide the
-        * compressed size of the resource we wrote.  Otherwise, the compressed
-        * size of the written resource is the same as the compressed size of
-        * the existing resource. */
-       if (out_ctype != WIM_COMPRESSION_TYPE_NONE && !raw) {
-               ret = finish_wim_resource_chunk_tab(chunk_tab, out_fp,
-                                                   &new_compressed_size);
-               if (ret != 0)
-                       goto out_fclose;
-       } else {
-               new_compressed_size = old_compressed_size;
-       }
-
-       /* Verify SHA1 message digest of the resource, unless we are doing a raw
-        * write (in which case we never even saw the uncompressed data).  Or,
-        * if the hash we had before is all 0's, just re-set it to be the new
-        * hash. */
-       if (!raw) {
-               u8 md[SHA1_HASH_SIZE];
-               sha1_final(md, &ctx);
-               if (is_zero_hash(lte->hash)) {
-                       copy_hash(lte->hash, md);
-               } else if (!hashes_equal(md, lte->hash)) {
-                       ERROR("WIM resource has incorrect hash!");
-                       if (lte->resource_location == RESOURCE_IN_FILE_ON_DISK) {
-                               ERROR("We were reading it from `%s'; maybe it changed "
-                                     "while we were reading it.",
-                                     lte->file_on_disk);
-                       }
-                       ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
-                       goto out_fclose;
-               }
-       }
-
-       if (new_compressed_size > original_size) {
-               /* Oops!  We compressed the resource to larger than the original
-                * size.  Write the resource uncompressed instead. */
-               if (fseeko(out_fp, file_offset, SEEK_SET) != 0) {
-                       ERROR_WITH_ERRNO("Failed to seek to byte "PRIu64" "
-                                        "of output WIM file", file_offset);
-                       ret = WIMLIB_ERR_WRITE;
-                       goto out_fclose;
-               }
-               ret = write_wim_resource(lte, out_fp, WIM_COMPRESSION_TYPE_NONE,
-                                        out_res_entry);
-               if (ret != 0)
-                       goto out_fclose;
-               if (fflush(out_fp) != 0) {
-                       ERROR_WITH_ERRNO("Failed to flush output WIM file");
-                       ret = WIMLIB_ERR_WRITE;
-                       goto out_fclose;
-               }
-               if (ftruncate(fileno(out_fp), file_offset + out_res_entry->size) != 0) {
-                       ERROR_WITH_ERRNO("Failed to truncate output WIM file");
-                       ret = WIMLIB_ERR_WRITE;
-               }
-               goto out_fclose;
-       }
-       wimlib_assert(new_compressed_size <= original_size);
-       if (out_res_entry) {
-               out_res_entry->size          = new_compressed_size;
-               out_res_entry->original_size = original_size;
-               out_res_entry->offset        = file_offset;
-               out_res_entry->flags         = lte->resource_entry.flags
-                                               & ~WIM_RESHDR_FLAG_COMPRESSED;
-               if (out_ctype != WIM_COMPRESSION_TYPE_NONE)
-                       out_res_entry->flags |= WIM_RESHDR_FLAG_COMPRESSED;
-       }
-out_fclose:
-       if (lte->resource_location == RESOURCE_IN_FILE_ON_DISK
-            && lte->file_on_disk_fp) {
-               fclose(lte->file_on_disk_fp);
-               lte->file_on_disk_fp = NULL;
-       }
-out:
-       FREE(chunk_tab);
-       return ret;
+       return read_wim_resource(lte, buf, wim_resource_size(lte), 0, flags);
 }
 
 /* Like write_wim_resource(), but the resource is specified by a buffer of
@@ -902,7 +616,7 @@ static int write_wim_resource_from_buffer(const u8 *buf, u64 buf_size,
                                          struct resource_entry *out_res_entry,
                                          u8 hash[SHA1_HASH_SIZE])
 {
-       /* Set up a temporary lookup table entry that we provide to
+       /* Set up a temporary lookup table entry to provide to
         * write_wim_resource(). */
        struct lookup_table_entry lte;
        int ret;
@@ -913,25 +627,25 @@ static int write_wim_resource_from_buffer(const u8 *buf, u64 buf_size,
        lte.resource_location            = RESOURCE_IN_ATTACHED_BUFFER;
        lte.attached_buffer              = (u8*)buf;
 
-       zero_hash(lte.hash);
-       ret = write_wim_resource(&lte, out_fp, out_ctype, out_res_entry);
+       zero_out_hash(lte.hash);
+       ret = write_wim_resource(&lte, out_fp, out_ctype, out_res_entry, 0);
        if (ret != 0)
                return ret;
        copy_hash(hash, lte.hash);
        return 0;
 }
 
-/* 
+/*
  * Extracts the first @size bytes of the WIM resource specified by @lte to the
  * open file descriptor @fd.
- * 
+ *
  * Returns 0 on success; nonzero on failure.
  */
 int extract_wim_resource_to_fd(const struct lookup_table_entry *lte, int fd,
                               u64 size)
 {
        u64 bytes_remaining = size;
-       char buf[min(WIM_CHUNK_SIZE, bytes_remaining)];
+       u8 buf[min(WIM_CHUNK_SIZE, bytes_remaining)];
        u64 offset = 0;
        int ret = 0;
        u8 hash[SHA1_HASH_SIZE];
@@ -941,11 +655,11 @@ int extract_wim_resource_to_fd(const struct lookup_table_entry *lte, int fd,
 
        while (bytes_remaining) {
                u64 to_read = min(bytes_remaining, WIM_CHUNK_SIZE);
-               ret = read_wim_resource(lte, buf, to_read, offset, false);
+               ret = read_wim_resource(lte, buf, to_read, offset, 0);
                if (ret != 0)
                        break;
                sha1_update(&ctx, buf, to_read);
-               if (full_write(fd, buf, to_read) < 0) {
+               if (full_write(fd, buf, to_read) < to_read) {
                        ERROR_WITH_ERRNO("Error extracting WIM resource");
                        return WIMLIB_ERR_WRITE;
                }
@@ -963,9 +677,9 @@ int extract_wim_resource_to_fd(const struct lookup_table_entry *lte, int fd,
        return 0;
 }
 
-/* 
+/*
  * Extracts the WIM resource specified by @lte to the open file descriptor @fd.
- * 
+ *
  * Returns 0 on success; nonzero on failure.
  */
 int extract_full_wim_resource_to_fd(const struct lookup_table_entry *lte, int fd)
@@ -973,7 +687,7 @@ int extract_full_wim_resource_to_fd(const struct lookup_table_entry *lte, int fd
        return extract_wim_resource_to_fd(lte, fd, wim_resource_size(lte));
 }
 
-/* 
+/*
  * Copies the file resource specified by the lookup table entry @lte from the
  * input WIM to the output WIM that has its FILE * given by
  * ((WIMStruct*)wim)->out_fp.
@@ -994,8 +708,8 @@ int copy_resource(struct lookup_table_entry *lte, void *wim)
                return 0;
 
        ret = write_wim_resource(lte, w->out_fp,
-                                wim_resource_compression_type(lte), 
-                                &lte->output_resource_entry);
+                                wim_resource_compression_type(lte),
+                                &lte->output_resource_entry, 0);
        if (ret != 0)
                return ret;
        lte->out_refcnt = lte->refcnt;
@@ -1003,40 +717,7 @@ int copy_resource(struct lookup_table_entry *lte, void *wim)
        return 0;
 }
 
-/* 
- * Writes a dentry's resources, including the main file resource as well as all
- * alternate data streams, to the output file. 
- *
- * @dentry:  The dentry for the file.
- * @wim_p:   A pointer to the WIMStruct containing @dentry.
- *
- * @return zero on success, nonzero on failure. 
- */
-int write_dentry_resources(struct dentry *dentry, void *wim_p)
-{
-       WIMStruct *w = wim_p;
-       int ret = 0;
-       struct lookup_table_entry *lte;
-       int ctype = wimlib_get_compression_type(w);
-
-       if (w->write_flags & WIMLIB_WRITE_FLAG_VERBOSE) {
-               wimlib_assert(dentry->full_path_utf8);
-               printf("Writing streams for `%s'\n", dentry->full_path_utf8);
-       }
-
-       for (unsigned i = 0; i <= dentry->num_ads; i++) {
-               lte = dentry_stream_lte(dentry, i, w->lookup_table);
-               if (lte && ++lte->out_refcnt == 1) {
-                       ret = write_wim_resource(lte, w->out_fp, ctype,
-                                                &lte->output_resource_entry);
-                       if (ret != 0)
-                               break;
-               }
-       }
-       return ret;
-}
-
-/* 
+/*
  * Reads the metadata metadata resource from the WIM file.  The metadata
  * resource consists of the security data, followed by the directory entry for
  * the root directory, followed by all the other directory entries in the
@@ -1054,59 +735,82 @@ int write_dentry_resources(struct dentry *dentry, void *wim_p)
  *
  * @return:    Zero on success, nonzero on failure.
  */
-int read_metadata_resource(FILE *fp, int wim_ctype, struct image_metadata *imd)
+int read_metadata_resource(WIMStruct *w, struct image_metadata *imd)
 {
        u8 *buf;
-       int ctype;
        u32 dentry_offset;
        int ret;
        struct dentry *dentry;
-       struct wim_security_data *sd;
-       struct link_group_table *lgt;
+       struct inode_table inode_tab;
        const struct lookup_table_entry *metadata_lte;
-       const struct resource_entry *res_entry;
+       u64 metadata_len;
+       u64 metadata_offset;
+       struct hlist_head inode_list;
 
        metadata_lte = imd->metadata_lte;
-       res_entry = &metadata_lte->resource_entry;
+       metadata_len = wim_resource_size(metadata_lte);
+       metadata_offset = metadata_lte->resource_entry.offset;
 
        DEBUG("Reading metadata resource: length = %"PRIu64", "
-             "offset = %"PRIu64"",
-             res_entry->original_size, res_entry->offset);
+             "offset = %"PRIu64"", metadata_len, metadata_offset);
+
+       /* There is no way the metadata resource could possibly be less than (8
+        * + WIM_DENTRY_DISK_SIZE) bytes, where the 8 is for security data (with
+        * no security descriptors) and WIM_DENTRY_DISK_SIZE is for the root
+        * dentry. */
+       if (metadata_len < 8 + WIM_DENTRY_DISK_SIZE) {
+               ERROR("Expected at least %u bytes for the metadata resource",
+                     8 + WIM_DENTRY_DISK_SIZE);
+               return WIMLIB_ERR_INVALID_RESOURCE_SIZE;
+       }
 
-       if (res_entry->original_size < 8) {
-               ERROR("Expected at least 8 bytes for the metadata resource");
+       if (sizeof(size_t) < 8 && metadata_len > 0xffffffff) {
+               ERROR("Metadata resource is too large (%"PRIu64" bytes",
+                     metadata_len);
                return WIMLIB_ERR_INVALID_RESOURCE_SIZE;
        }
 
        /* Allocate memory for the uncompressed metadata resource. */
-       buf = MALLOC(res_entry->original_size);
+       buf = MALLOC(metadata_len);
 
        if (!buf) {
                ERROR("Failed to allocate %"PRIu64" bytes for uncompressed "
-                     "metadata resource", res_entry->original_size);
+                     "metadata resource", metadata_len);
                return WIMLIB_ERR_NOMEM;
        }
 
-       /* Determine the compression type of the metadata resource. */
-
        /* Read the metadata resource into memory.  (It may be compressed.) */
-       ret = read_full_wim_resource(metadata_lte, buf);
+       ret = read_full_wim_resource(metadata_lte, buf, 0);
        if (ret != 0)
                goto out_free_buf;
 
        DEBUG("Finished reading metadata resource into memory.");
 
-       /* The root directory entry starts after security data, on an 8-byte
-        * aligned address. 
+       /* The root directory entry starts after security data, aligned on an
+        * 8-byte boundary within the metadata resource.
         *
         * The security data starts with a 4-byte integer giving its total
-        * length. */
+        * length, so if we round that up to an 8-byte boundary that gives us
+        * the offset of the root dentry.
+        *
+        * Here we read the security data into a wim_security_data structure,
+        * and if successful, go ahead and calculate the offset in the metadata
+        * resource of the root dentry. */
 
-       /* Read the security data into a wim_security_data structure. */
-       ret = read_security_data(buf, res_entry->original_size, &sd);
+       wimlib_assert(imd->security_data == NULL);
+       ret = read_security_data(buf, metadata_len, &imd->security_data);
        if (ret != 0)
                goto out_free_buf;
 
+       dentry_offset = (imd->security_data->total_length + 7) & ~7;
+
+       if (dentry_offset == 0) {
+               ERROR("Integer overflow while reading metadata resource");
+               ret = WIMLIB_ERR_INVALID_SECURITY_DATA;
+               goto out_free_security_data;
+       }
+
+       /* Allocate memory for the root dentry and read it into memory */
        dentry = MALLOC(sizeof(struct dentry));
        if (!dentry) {
                ERROR("Failed to allocate %zu bytes for root dentry",
@@ -1115,56 +819,57 @@ int read_metadata_resource(FILE *fp, int wim_ctype, struct image_metadata *imd)
                goto out_free_security_data;
        }
 
-       get_u32(buf, &dentry_offset);
-       if (dentry_offset == 0)
-               dentry_offset = 8;
-       dentry_offset = (dentry_offset + 7) & ~7;
-               
-       ret = read_dentry(buf, res_entry->original_size, dentry_offset, dentry);
-       /* This is the root dentry, so set its pointers correctly. */
+       ret = read_dentry(buf, metadata_len, dentry_offset, dentry);
+
+       /* This is the root dentry, so set its parent to itself. */
        dentry->parent = dentry;
-       dentry->next   = dentry;
-       dentry->prev   = dentry;
+
        if (ret != 0)
                goto out_free_dentry_tree;
+       inode_add_dentry(dentry, dentry->d_inode);
 
+       /* Now read the entire directory entry tree into memory. */
        DEBUG("Reading dentry tree");
-       /* Now read the entire directory entry tree. */
-       ret = read_dentry_tree(buf, res_entry->original_size, dentry);
+       ret = read_dentry_tree(buf, metadata_len, dentry);
        if (ret != 0)
                goto out_free_dentry_tree;
 
-       DEBUG("Calculating dentry full paths");
        /* Calculate the full paths in the dentry tree. */
+       DEBUG("Calculating dentry full paths");
        ret = for_dentry_in_tree(dentry, calculate_dentry_full_path, NULL);
        if (ret != 0)
                goto out_free_dentry_tree;
 
-       DEBUG("Building link group table");
        /* Build hash table that maps hard link group IDs to dentry sets */
-       lgt = new_link_group_table(9001);
-       if (!lgt)
+       DEBUG("Building link group table");
+       ret = init_inode_table(&inode_tab, 9001);
+       if (ret != 0)
                goto out_free_dentry_tree;
-       ret = for_dentry_in_tree(dentry, link_group_table_insert, lgt);
+
+       for_dentry_in_tree(dentry, inode_table_insert, &inode_tab);
+
+       DEBUG("Fixing inconsistencies in the hard link groups");
+       ret = fix_inodes(&inode_tab, &inode_list);
+       destroy_inode_table(&inode_tab);
        if (ret != 0)
-               goto out_free_lgt;
+               goto out_free_dentry_tree;
 
-       DEBUG("Freeing duplicate ADS entries in link group table");
-       ret = link_groups_free_duplicate_data(lgt);
+       DEBUG("Running miscellaneous verifications on the dentry tree");
+       for_lookup_table_entry(w->lookup_table, lte_zero_real_refcnt, NULL);
+       ret = for_dentry_in_tree(dentry, verify_dentry, w);
        if (ret != 0)
-               goto out_free_lgt;
+               goto out_free_dentry_tree;
+
        DEBUG("Done reading image metadata");
 
-       imd->lgt           = lgt;
-       imd->security_data = sd;
-       imd->root_dentry   = dentry;
+       imd->root_dentry = dentry;
+       imd->inode_list  = inode_list;
        goto out_free_buf;
-out_free_lgt:
-       free_link_group_table(lgt);
 out_free_dentry_tree:
        free_dentry_tree(dentry, NULL);
 out_free_security_data:
-       free_security_data(sd);
+       free_security_data(imd->security_data);
+       imd->security_data = NULL;
 out_free_buf:
        FREE(buf);
        return ret;
@@ -1180,18 +885,35 @@ int write_metadata_resource(WIMStruct *w)
        struct dentry *root;
        struct lookup_table_entry *lte;
        u64 metadata_original_size;
+       const struct wim_security_data *sd;
 
        DEBUG("Writing metadata resource for image %d", w->current_image);
 
        root = wim_root_dentry(w);
+       sd = wim_security_data(w);
+
+       /* We do not allow the security data pointer to be NULL, although it may
+        * point to an empty security data with no entries. */
+       wimlib_assert(root != NULL);
+       wimlib_assert(sd != NULL);
+
+       /* Offset of first child of the root dentry.  It's equal to:
+        * - The total length of the security data, rounded to the next 8-byte
+        *   boundary,
+        * - plus the total length of the root dentry,
+        * - plus 8 bytes for an end-of-directory entry following the root
+        *   dentry (shouldn't really be needed, but just in case...)
+        */
+       subdir_offset = ((sd->total_length + 7) & ~7) +
+                       dentry_correct_total_length(root) + 8;
 
-       struct wim_security_data *sd = wim_security_data(w);
-       if (sd)
-               subdir_offset = sd->total_length + root->length + 8;
-       else
-               subdir_offset = 8 + root->length + 8;
+       /* Calculate the subdirectory offsets for the entire dentry tree. */
        calculate_subdir_offsets(root, &subdir_offset);
+
+       /* Total length of the metadata resource (uncompressed) */
        metadata_original_size = subdir_offset;
+
+       /* Allocate a buffer to contain the uncompressed metadata resource */
        buf = MALLOC(metadata_original_size);
        if (!buf) {
                ERROR("Failed to allocate %"PRIu64" bytes for "
@@ -1199,24 +921,55 @@ int write_metadata_resource(WIMStruct *w)
                return WIMLIB_ERR_NOMEM;
        }
 
+       /* Write the security data into the resource buffer */
        p = write_security_data(sd, buf);
 
-       DEBUG("Writing dentry tree.");
+       /* Write the dentry tree into the resource buffer */
        p = write_dentry_tree(root, p);
+
+       /* We MUST have exactly filled the buffer; otherwise we calculated its
+        * size incorrectly or wrote the data incorrectly. */
        wimlib_assert(p - buf == metadata_original_size);
 
+       /* Get the lookup table entry for the metadata resource so we can update
+        * it. */
        lte = wim_metadata_lookup_table_entry(w);
 
+       wimlib_assert(lte != NULL);
+
+       /* Write the metadata resource to the output WIM using the proper
+        * compression type.  The lookup table entry for the metadata resource
+        * is updated. */
        ret = write_wim_resource_from_buffer(buf, metadata_original_size,
                                             w->out_fp,
                                             wimlib_get_compression_type(w),
                                             &lte->output_resource_entry,
                                             lte->hash);
+       if (ret != 0)
+               goto out;
 
+       /* It's very likely the SHA1 message digest of the metadata resource
+        * changed, so re-insert the lookup table entry into the lookup table.
+        *
+        * We do not check for other lookup table entries having the same SHA1
+        * message digest.  It's possible for 2 absolutely identical images to
+        * be added, therefore causing 2 identical metadata resources to be in
+        * the WIM.  However, in this case, it's expected for 2 separate lookup
+        * table entries to be created, even though this doesn't make a whole
+        * lot of sense since they will share the same SHA1 message digest.
+        * */
        lookup_table_unlink(w->lookup_table, lte);
        lookup_table_insert(w->lookup_table, lte);
-       lte->out_refcnt++;
+
+       wimlib_assert(lte->out_refcnt == 0);
+       lte->out_refcnt = 1;
+
+       /* Make sure that the resource entry is written marked with the metadata
+        * flag. */
        lte->output_resource_entry.flags |= WIM_RESHDR_FLAG_METADATA;
+out:
+       /* All the data has been written to the new WIM; no need for the buffer
+        * anymore */
        FREE(buf);
        return ret;
 }