]> wimlib.net Git - wimlib/blobdiff - src/resource.c
win32_read_file: Use UTF16-LE name
[wimlib] / src / resource.c
index cd098f92ad5e6edd5990aa68971e5351b1007237..ee2b2941c8448ed13821855e9cb5a65669f49e68 100644 (file)
@@ -1,11 +1,11 @@
 /*
  * resource.c
  *
- * Read uncompressed and compressed metadata and file resources.
+ * Read uncompressed and compressed metadata and file resources from a WIM file.
  */
 
 /*
- * Copyright (C) 2012 Eric Biggers
+ * Copyright (C) 2012, 2013 Eric Biggers
  *
  * This file is part of wimlib, a library for working with WIM files.
  *
  * wimlib; if not, see http://www.gnu.org/licenses/.
  */
 
-#include "config.h"
-
-#include <stdlib.h>
-#include <stdarg.h>
-
-#ifdef WITH_NTFS_3G
-#include <ntfs-3g/attrib.h>
-#include <ntfs-3g/inode.h>
-#include <ntfs-3g/dir.h>
-#endif
-
 #include "wimlib_internal.h"
+#include "dentry.h"
 #include "lookup_table.h"
-#include "io.h"
+#include "buffer_io.h"
 #include "lzx.h"
 #include "xpress.h"
 #include "sha1.h"
-#include "dentry.h"
-#include <unistd.h>
+
+#ifdef __WIN32__
+#  include "win32.h"
+#endif
+
 #include <errno.h>
-#ifdef HAVE_ALLOCA_H
-#include <alloca.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#ifdef WITH_NTFS_3G
+#  include <time.h>
+#  include <ntfs-3g/attrib.h>
+#  include <ntfs-3g/inode.h>
+#  include <ntfs-3g/dir.h>
 #endif
 
+#if defined(__WIN32__) && !defined(INVALID_HANDLE_VALUE)
+#  define INVALID_HANDLE_VALUE ((HANDLE)(-1))
+#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
  *
  * 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, 
-                                   u64 len, u64 offset, u8  contents_ret[])
+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, void *contents_ret)
 {
 
        DEBUG2("comp size = %"PRIu64", uncomp size = %"PRIu64", "
@@ -82,9 +86,9 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
        if (len == 0)
                return 0;
 
-       int (*decompress)(const void *, uint, void *, uint);
+       int (*decompress)(const void *, unsigned, void *, unsigned);
        /* Set the appropriate decompress function. */
-       if (resource_ctype == WIM_COMPRESSION_TYPE_LZX)
+       if (resource_ctype == WIMLIB_COMPRESSION_TYPE_LZX)
                decompress = lzx_decompress;
        else
                decompress = xpress_decompress;
@@ -98,7 +102,7 @@ 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. */
@@ -146,7 +150,7 @@ 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. */
@@ -160,11 +164,11 @@ 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 "
@@ -201,7 +205,7 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
        /* 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 "
@@ -212,7 +216,7 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
 
        /* Pointer to current position in the output buffer for uncompressed
         * data. */
-       u8 *out_p = (u8*)contents_ret;
+       u8 *out_p = contents_ret;
 
        /* Buffer for compressed data.  While most compressed chunks will have a
         * size much less than WIM_CHUNK_SIZE, WIM_CHUNK_SIZE - 1 is the maximum
@@ -231,13 +235,14 @@ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size,
 
                /* Calculate the sizes of the compressed chunk and of the
                 * uncompressed chunk. */
-               uint compressed_chunk_size, uncompressed_chunk_size;
+               unsigned compressed_chunk_size;
+               unsigned uncompressed_chunk_size;
                if (i != num_chunks - 1) {
                        /* All the chunks except the last one in the resource
                         * 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 {
@@ -245,15 +250,15 @@ 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
@@ -280,12 +285,12 @@ 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,
-                                       end_offset);
-               DEBUG2("partial_chunk_size = %u", partial_chunk_size);
+               DEBUG2("start_offset = %"PRIu64", end_offset = %"PRIu64"",
+                      start_offset, end_offset);
+               DEBUG2("partial_chunk_size = %"PRIu64"", partial_chunk_size);
 
                /* This is undocumented, but chunks can be uncompressed.  This
                 * appears to always be the case when the compressed chunk size
@@ -300,7 +305,7 @@ 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 {
@@ -308,7 +313,7 @@ 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;
 
@@ -319,7 +324,7 @@ 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;
@@ -350,11 +355,11 @@ err:
        return WIMLIB_ERR_READ;
 }
 
-/* 
+/*
  * Reads uncompressed data from an open file stream.
  */
-int read_uncompressed_resource(FILE *fp, u64 offset, u64 len,
-                              u8 contents_ret[])
+int
+read_uncompressed_resource(FILE *fp, u64 offset, u64 len, void *contents_ret)
 {
        if (fseeko(fp, offset, SEEK_SET) != 0) {
                ERROR("Failed to seek to byte %"PRIu64" of input file "
@@ -375,13 +380,11 @@ int read_uncompressed_resource(FILE *fp, u64 offset, u64 len,
        return 0;
 }
 
-
-
-
 /* Reads the contents of a struct resource_entry, as represented in the on-disk
  * format, from the memory pointed to by @p, and fills in the fields of @entry.
  * A pointer to the byte after the memory read at @p is returned. */
-const u8 *get_resource_entry(const u8 *p, struct resource_entry *entry)
+const u8 *
+get_resource_entry(const u8 *p, struct resource_entry *entry)
 {
        u64 size;
        u8 flags;
@@ -390,15 +393,29 @@ 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;
 }
 
 /* Copies the struct resource_entry @entry to the memory pointed to by @p in the
  * on-disk format.  A pointer to the byte after the memory written at @p is
  * returned. */
-u8 *put_resource_entry(u8 *p, const struct resource_entry *entry)
+u8 *
+put_resource_entry(u8 *p, const struct resource_entry *entry)
 {
        p = put_u56(p, entry->size);
        p = put_u8(p, entry->flags);
@@ -407,6 +424,61 @@ 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 /* !WITH_FUSE */
+
 /*
  * Reads some data from the resource corresponding to a WIM lookup table entry.
  *
@@ -414,54 +486,75 @@ 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)
+int
+read_wim_resource(const struct wim_lookup_table_entry *lte, void *buf,
+                 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);
 
-               wimlib_assert(ctype != WIM_COMPRESSION_TYPE_NONE ||
+               wimlib_assert(ctype != WIMLIB_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 == WIMLIB_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:
        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);
+               wimlib_assert(lte->file_on_disk != NULL);
+               BUILD_BUG_ON(&lte->file_on_disk != &lte->staging_file_name);
                /* Use existing file pointer if available; otherwise open one
                 * temporarily */
                if (lte->file_on_disk_fp) {
@@ -471,49 +564,51 @@ 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);
-                               return WIMLIB_ERR_OPEN;
+                               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;
+#ifdef __WIN32__
+       case RESOURCE_WIN32:
+               wimlib_assert(lte->win32_file_on_disk_fp != INVALID_HANDLE_VALUE);
+               ret = win32_read_file(lte->win32_file_on_disk,
+                                     lte->win32_file_on_disk_fp, offset, size,
+                                     buf);
+               break;
+#endif
        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);
-               if (lte->attr) {
-                       u64 adjusted_offset;
-                       if (lte->ntfs_loc->is_reparse_point)
-                               adjusted_offset = offset + 8;
-                       else
-                               adjusted_offset = offset;
-                       if (ntfs_attr_pread(lte->attr, offset, size, buf) == size) {
-                               return 0;
-                       } else {
-                               ERROR_WITH_ERRNO("Error reading NTFS attribute "
-                                                "at `%s'",
-                                                lte->ntfs_loc->path_utf8);
-                               return WIMLIB_ERR_NTFS_3G;
-                       }
-               } else {
-                       wimlib_assert(0);
+               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);
+                       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.
  *
@@ -523,525 +618,103 @@ 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)
+int
+read_full_wim_resource(const struct wim_lookup_table_entry *lte,
+                      void *buf, int flags)
 {
-       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;
+       return read_wim_resource(lte, buf, wim_resource_size(lte), 0, flags);
 }
 
-/* 
- * Compresses a chunk of a WIM resource.
+/* Extracts the first @size bytes of a WIM resource to somewhere.  In the
+ * process, the SHA1 message digest of the resource is checked if the full
+ * resource is being extracted.
  *
- * @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)
+ * @extract_chunk is a function that is called to extract each chunk of the
+ * resource. */
+int
+extract_wim_resource(const struct wim_lookup_table_entry *lte,
+                    u64 size,
+                    extract_chunk_func_t extract_chunk,
+                    void *extract_chunk_arg)
 {
-       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;
-
-               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_cpu_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] =
-                               cpu_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)
-{
-       u64 bytes_remaining;
-       u64 original_size;
-       u64 old_compressed_size;
-       u64 new_compressed_size;
+       u64 bytes_remaining = size;
+       u8 buf[min(WIM_CHUNK_SIZE, bytes_remaining)];
        u64 offset = 0;
        int ret = 0;
-       struct chunk_table *chunk_tab = NULL;
-       bool raw;
-       off_t file_offset;
-#ifdef WITH_NTFS_3G
-       ntfs_inode *ni = NULL;
-#endif
-
-       wimlib_assert(lte);
-
-       /* 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 */
-       u8 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;
-               }
-       }
-#ifdef WITH_NTFS_3G
-       else if (lte->resource_location == RESOURCE_IN_NTFS_VOLUME
-                 && !lte->attr)
-       {
-               struct ntfs_location *loc = lte->ntfs_loc;
-               wimlib_assert(loc);
-               ni = ntfs_pathname_to_inode(*loc->ntfs_vol_p, NULL, loc->path_utf8);
-               if (!ni) {
-                       ERROR_WITH_ERRNO("Failed to open inode `%s' in NTFS "
-                                        "volume", loc->path_utf8);
-                       ret = WIMLIB_ERR_NTFS_3G;
-                       goto out;
-               }
-               lte->attr = ntfs_attr_open(ni,
-                                          loc->is_reparse_point ? AT_REPARSE_POINT : AT_DATA,
-                                          (ntfschar*)loc->stream_name_utf16,
-                                          loc->stream_name_utf16_num_chars);
-               if (!lte->attr) {
-                       ERROR_WITH_ERRNO("Failed to open attribute of `%s' in "
-                                        "NTFS volume", loc->path_utf8);
-                       ret = WIMLIB_ERR_NTFS_3G;
-                       goto out_fclose;
-               }
-       }
-#endif
-
-       /* 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. */
+       u8 hash[SHA1_HASH_SIZE];
+       bool check_hash = (size == wim_resource_size(lte));
        SHA_CTX ctx;
-       if (!raw)
+
+       if (check_hash)
                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);
+       while (bytes_remaining) {
+               u64 to_read = min(bytes_remaining, sizeof(buf));
+               ret = read_wim_resource(lte, buf, to_read, offset, 0);
                if (ret != 0)
-                       goto out_fclose;
-               if (!raw)
+                       return ret;
+               if (check_hash)
                        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;
+               ret = extract_chunk(buf, to_read, offset, extract_chunk_arg);
+               if (ret != 0) {
+                       ERROR_WITH_ERRNO("Error extracting WIM resource");
+                       return ret;
+               }
                bytes_remaining -= to_read;
                offset += to_read;
-       } while (bytes_remaining);
-
-       /* Raw copy:  The new compressed size is the same as the old compressed
-        * size
-        * 
-        * Using WIM_COMPRESSION_TYPE_NONE:  The new compressed size is the
-        * original size
-        *
-        * Using a different compression type:  Call
-        * finish_wim_resource_chunk_tab() and it will provide the new
-        * compressed size.
-        */
-       if (raw) {
-               new_compressed_size = old_compressed_size;
-       } else {
-               if (out_ctype == WIM_COMPRESSION_TYPE_NONE)
-                       new_compressed_size = original_size;
-               else {
-                       ret = finish_wim_resource_chunk_tab(chunk_tab, out_fp,
-                                                           &new_compressed_size);
-                       if (ret != 0)
-                               goto out_fclose;
-               }
        }
-
-       /* 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 (check_hash) {
+               sha1_final(hash, &ctx);
+               if (!hashes_equal(hash, lte->hash)) {
+               #ifdef ENABLE_ERROR_MESSAGES
+                       ERROR("Invalid checksum on the following WIM resource:");
+                       print_lookup_table_entry(lte, stderr);
+               #endif
+                       return WIMLIB_ERR_INVALID_RESOURCE_HASH;
                }
        }
-
-       if (!raw && new_compressed_size >= original_size &&
-           out_ctype != WIM_COMPRESSION_TYPE_NONE)
-       {
-               /* 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 || raw);
-       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;
-       }
-#ifdef WITH_NTFS_3G
-       else if (lte->resource_location == RESOURCE_IN_NTFS_VOLUME) {
-               if (lte->attr) {
-                       ntfs_attr_close(lte->attr);
-                       lte->attr = NULL;
-               } if (ni) {
-                       ntfs_inode_close(ni);
-               }
-       }
-#endif
-out:
-       FREE(chunk_tab);
-       return ret;
-}
-
-/* Like write_wim_resource(), but the resource is specified by a buffer of
- * uncompressed data rather a lookup table entry; also writes the SHA1 hash of
- * the buffer to @hash.  */
-static int write_wim_resource_from_buffer(const u8 *buf, u64 buf_size,
-                                         FILE *out_fp, int out_ctype,
-                                         struct resource_entry *out_res_entry,
-                                         u8 hash[SHA1_HASH_SIZE])
-{
-       /* Set up a temporary lookup table entry that we provide to
-        * write_wim_resource(). */
-       struct lookup_table_entry lte;
-       int ret;
-       lte.resource_entry.flags         = 0;
-       lte.resource_entry.original_size = buf_size;
-       lte.resource_entry.size          = buf_size;
-       lte.resource_entry.offset        = 0;
-       lte.resource_location            = RESOURCE_IN_ATTACHED_BUFFER;
-       lte.attached_buffer              = (u8*)buf;
-
-       zero_out_hash(lte.hash);
-       ret = write_wim_resource(&lte, out_fp, out_ctype, out_res_entry);
-       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)
+/* Write @n bytes from @buf to the file descriptor @fd, retrying on internupt
+ * and on short writes.
+ *
+ * Returns short count and set errno on failure. */
+static ssize_t
+full_write(int fd, const void *buf, size_t n)
 {
-       u64 bytes_remaining = size;
-       u8 buf[min(WIM_CHUNK_SIZE, bytes_remaining)];
-       u64 offset = 0;
-       int ret = 0;
-       u8 hash[SHA1_HASH_SIZE];
-
-       SHA_CTX ctx;
-       sha1_init(&ctx);
-
-       while (bytes_remaining) {
-               u64 to_read = min(bytes_remaining, WIM_CHUNK_SIZE);
-               ret = read_wim_resource(lte, buf, to_read, offset, false);
-               if (ret != 0)
-                       break;
-               sha1_update(&ctx, buf, to_read);
-               if (full_write(fd, buf, to_read) < to_read) {
-                       ERROR_WITH_ERRNO("Error extracting WIM resource");
-                       return WIMLIB_ERR_WRITE;
+       const void *p = buf;
+       ssize_t ret;
+       ssize_t total = 0;
+
+       while (total != n) {
+               ret = write(fd, p, n);
+               if (ret < 0) {
+                       if (errno == EINTR)
+                               continue;
+                       else
+                               break;
                }
-               bytes_remaining -= to_read;
-               offset += to_read;
+               total += ret;
+               p += ret;
        }
-       sha1_final(hash, &ctx);
-       if (!hashes_equal(hash, lte->hash)) {
-               ERROR("Invalid checksum on a WIM resource "
-                     "(detected when extracting to external file)");
-               ERROR("The following WIM resource is invalid:");
-               print_lookup_table_entry(lte);
-               return WIMLIB_ERR_INVALID_RESOURCE_HASH;
-       }
-       return 0;
+       return total;
 }
 
-/* 
- * 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)
+int
+extract_wim_chunk_to_fd(const void *buf, size_t len, u64 offset, void *arg)
 {
-       return extract_wim_resource_to_fd(lte, fd, wim_resource_size(lte));
+       int fd = *(int*)arg;
+       ssize_t ret = full_write(fd, buf, len);
+       if (ret < len) {
+               ERROR_WITH_ERRNO("Error writing to file descriptor");
+               return WIMLIB_ERR_WRITE;
+       } else {
+               return 0;
+       }
 }
 
-/* 
+/*
  * 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.
@@ -1049,10 +722,10 @@ int extract_full_wim_resource_to_fd(const struct lookup_table_entry *lte, int fd
  * The output_resource_entry, out_refcnt, and part_number fields of @lte are
  * updated.
  *
- * Metadata resources are not copied (they are handled elsewhere for joining and
- * splitting).
+ * (This function is confusing and should be refactored somehow.)
  */
-int copy_resource(struct lookup_table_entry *lte, void *wim)
+int
+copy_resource(struct wim_lookup_table_entry *lte, void *wim)
 {
        WIMStruct *w = wim;
        int ret;
@@ -1062,297 +735,11 @@ 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;
        lte->part_number = w->hdr.part_number;
        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->d_inode->num_ads; i++) {
-               lte = inode_stream_lte(dentry->d_inode, 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
- * filesystem.  The subdir_offset field of each directory entry gives the start
- * of its child entries from the beginning of the metadata resource.  An
- * end-of-directory is signaled by a directory entry of length '0', really of
- * length 8, because that's how long the 'length' field is.
- *
- * @fp:                The FILE* for the input WIM file.
- * @wim_ctype: The compression type of the WIM file.
- * @imd:       Pointer to the image metadata structure.  Its `metadata_lte'
- *             member specifies the lookup table entry for the metadata
- *             resource.  The rest of the image metadata entry will be filled
- *             in by this function.
- *
- * @return:    Zero on success, nonzero on failure.
- */
-int read_metadata_resource(WIMStruct *w, struct image_metadata *imd)
-{
-       u8 *buf;
-       u32 dentry_offset;
-       int ret;
-       struct dentry *dentry;
-       struct inode_table inode_tab;
-       const struct lookup_table_entry *metadata_lte;
-       u64 metadata_len;
-       u64 metadata_offset;
-       struct hlist_head inode_list;
-
-       metadata_lte = imd->metadata_lte;
-       metadata_len = wim_resource_size(metadata_lte);
-       metadata_offset = metadata_lte->resource_entry.offset;
-
-       DEBUG("Reading metadata resource: length = %"PRIu64", "
-             "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;
-       }
-
-       /* Allocate memory for the uncompressed metadata resource. */
-       buf = MALLOC(metadata_len);
-
-       if (!buf) {
-               ERROR("Failed to allocate %"PRIu64" bytes for uncompressed "
-                     "metadata resource", metadata_len);
-               return WIMLIB_ERR_NOMEM;
-       }
-
-       /* Read the metadata resource into memory.  (It may be compressed.) */
-       ret = read_full_wim_resource(metadata_lte, buf);
-       if (ret != 0)
-               goto out_free_buf;
-
-       DEBUG("Finished reading metadata resource into memory.");
-
-       /* 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, 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. */
-
-       ret = read_security_data(buf, metadata_len, &imd->security_data);
-       if (ret != 0)
-               goto out_free_buf;
-
-       get_u32(buf, &dentry_offset);
-       if (dentry_offset == 0)
-               dentry_offset = 8;
-       dentry_offset = (dentry_offset + 7) & ~7;
-
-       /* 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",
-                     sizeof(struct dentry));
-               ret = WIMLIB_ERR_NOMEM;
-               goto out_free_security_data;
-       }
-               
-       ret = read_dentry(buf, metadata_len, dentry_offset, dentry);
-
-       /* This is the root dentry, so set its pointers correctly. */
-       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");
-       ret = read_dentry_tree(buf, metadata_len, dentry);
-       if (ret != 0)
-               goto out_free_dentry_tree;
-
-       /* 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;
-
-       /* Build hash table that maps hard link group IDs to dentry sets */
-       DEBUG("Building link group table");
-       ret = init_inode_table(&inode_tab, 9001);
-       if (ret != 0)
-               goto out_free_dentry_tree;
-
-       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_dentry_tree;
-
-       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_dentry_tree;
-
-       DEBUG("Done reading image metadata");
-
-       imd->root_dentry = dentry;
-       imd->inode_list  = inode_list;
-       goto out_free_buf;
-out_free_dentry_tree:
-       free_dentry_tree(dentry, NULL);
-out_free_security_data:
-       free_security_data(imd->security_data);
-       imd->security_data = NULL;
-out_free_buf:
-       FREE(buf);
-       return ret;
-}
-
-/* Write the metadata resource for the current WIM image. */
-int write_metadata_resource(WIMStruct *w)
-{
-       u8 *buf;
-       u8 *p;
-       int ret;
-       u64 subdir_offset;
-       struct dentry *root;
-       struct lookup_table_entry *lte;
-       u64 metadata_original_size;
-       const struct wim_security_data *sd;
-       const unsigned random_tail_len = 20;
-
-       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(sd);
-
-       /* 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;
-
-       /* 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 + random_tail_len;
-
-       /* Allocate a buffer to contain the uncompressed metadata resource */
-       buf = MALLOC(metadata_original_size);
-       if (!buf) {
-               ERROR("Failed to allocate %"PRIu64" bytes for "
-                     "metadata resource", metadata_original_size);
-               return WIMLIB_ERR_NOMEM;
-       }
-
-       /* Write the security data into the resource buffer */
-       p = write_security_data(sd, buf);
-
-       /* Write the dentry tree into the resource buffer */
-       DEBUG("Writing dentry tree.");
-       p = write_dentry_tree(root, p);
-
-       /* 
-        * Append 20 random bytes to the metadata resource so that we don't have
-        * identical metadata resources if we happen to append exactly the same
-        * image twice without any changes in timestamps.  If this were to
-        * happen, it would cause confusion about the number and order of images
-        * in the WIM.
-        */
-       randomize_byte_array(p, random_tail_len);
-
-       /* We MUST have exactly filled the buffer; otherwise we calculated its
-        * size incorrectly or wrote the data incorrectly. */
-       wimlib_assert(p - buf + random_tail_len == metadata_original_size);
-
-       /* Get the lookup table entry for the metadata resource so we can update
-        * it. */
-       lte = wim_metadata_lookup_table_entry(w);
-
-       /* 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.
-        * */
-       lookup_table_unlink(w->lookup_table, lte);
-       lookup_table_insert(w->lookup_table, lte);
-
-       /* We do not allow a metadata resource to be referenced multiple times,
-        * and the 20 random bytes appended to it should make it extremely
-        * likely for each metadata resource to be unique, even if the exact
-        * same image is captured. */
-       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;
-}