streamifier_cb(): Fix update of cur_stream_offset
[wimlib] / src / resource.c
index f54ea25..192ffb2 100644 (file)
@@ -1,7 +1,7 @@
 /*
  * resource.c
  *
- * Read uncompressed and compressed metadata and file resources from a WIM file.
+ * Code for reading streams and resources, including compressed WIM resources.
  */
 
 /*
  * wimlib; if not, see http://www.gnu.org/licenses/.
  */
 
-#include "wimlib_internal.h"
-#include "dentry.h"
-#include "lookup_table.h"
-#include "buffer_io.h"
-#include "sha1.h"
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
+#include "wimlib.h"
+#include "wimlib/endianness.h"
+#include "wimlib/error.h"
+#include "wimlib/file_io.h"
+#include "wimlib/lookup_table.h"
+#include "wimlib/resource.h"
+#include "wimlib/sha1.h"
 
 #ifdef __WIN32__
-#  include "win32.h"
+/* for read_win32_file_prefix(), read_win32_encrypted_file_prefix() */
+#  include "wimlib/win32.h"
 #endif
 
-#include <errno.h>
-#include <stdarg.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
+#ifdef WITH_NTFS_3G
+/* for read_ntfs_file_prefix() */
+#  include "wimlib/ntfs_3g.h"
+#endif
 
 #ifdef HAVE_ALLOCA_H
 #  include <alloca.h>
 #endif
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/*
+ *                         Compressed WIM resources
+ *
+ * A compressed resource in a WIM consists of a number of compressed chunks,
+ * each of which decompresses to a fixed chunk size (given in the WIM header;
+ * usually 32768) except possibly the last, which always decompresses to any
+ * remaining bytes.  In addition, immediately before the chunks, a table (the
+ * "chunk table") provides the offset, in bytes relative to the end of the chunk
+ * table, of the start of each compressed chunk, except for the first chunk
+ * which is omitted as it always has an offset of 0.  Therefore, a compressed
+ * resource with N chunks will have a chunk table with N - 1 entries.
+ *
+ * Additional information:
+ *
+ * - Entries in the chunk table are 4 bytes each, except if the uncompressed
+ *   size of the resource is greater than 4 GiB, in which case the entries in
+ *   the chunk table are 8 bytes each.  In either case, the entries are unsigned
+ *   little-endian integers.
+ *
+ * - The chunk table is included in the compressed size of the resource provided
+ *   in the corresponding entry in the WIM's stream lookup table.
+ *
+ * - The compressed size of a chunk is never greater than the uncompressed size.
+ *   From the compressor's point of view, chunks that would have compressed to a
+ *   size greater than or equal to their original size are in fact stored
+ *   uncompressed.  From the decompresser's point of view, chunks with
+ *   compressed size equal to their uncompressed size are in fact uncompressed.
+ *
+ * Furthermore, wimlib supports its own "pipable" WIM format, and for this the
+ * structure of compressed resources was modified to allow piped reading and
+ * writing.  To make sequential writing possible, the chunk table is placed
+ * after the chunks rather than before the chunks, and to make sequential
+ * reading possible, each chunk is prefixed with a 4-byte header giving its
+ * compressed size as a 32-bit, unsigned, little-endian integer.  Otherwise the
+ * details are the same.
+ */
+
+
+struct data_range {
+       u64 offset;
+       u64 size;
+};
 
 /*
- * Reads all or part of a compressed WIM resource.
+ * read_compressed_wim_resource() -
+ *
+ * Read data from a compressed WIM resource.
  *
- * Returns zero on success, nonzero on failure.
+ * @rspec
+ *     Specification of the compressed WIM resource to read from.
+ * @ranges
+ *     Nonoverlapping, nonempty ranges of the uncompressed resource data to
+ *     read, sorted by increasing offset.
+ * @num_ranges
+ *     Number of ranges in @ranges; must be at least 1.
+ * @cb
+ *     Callback function to feed the data being read.  Each call provides the
+ *     next chunk of the requested data, uncompressed.  Each chunk will be of
+ *     nonzero size and will not cross range boundaries, but otherwise will be
+ *     of unspecified size.
+ * @cb_ctx
+ *     Parameter to pass to @cb_ctx.
+ *
+ * Possible return values:
+ *
+ *     WIMLIB_ERR_SUCCESS (0)
+ *     WIMLIB_ERR_READ                   (errno set)
+ *     WIMLIB_ERR_UNEXPECTED_END_OF_FILE (errno set to 0)
+ *     WIMLIB_ERR_NOMEM                  (errno set to ENOMEM)
+ *     WIMLIB_ERR_DECOMPRESSION          (errno set to EINVAL)
+ *
+ *     or other error code returned by the @cb function.
  */
 static int
-read_compressed_resource(int in_fd,
-                        u64 resource_compressed_size,
-                        u64 resource_uncompressed_size,
-                        u64 resource_offset,
-                        int resource_ctype,
-                        u64 len,
-                        u64 offset,
-                        consume_data_callback_t cb,
-                        void *ctx_or_buf)
+read_compressed_wim_resource(const struct wim_resource_spec * const rspec,
+                            const struct data_range * const ranges,
+                            const size_t num_ranges,
+                            const consume_data_callback_t cb,
+                            void * const cb_ctx)
 {
        int ret;
+       int errno_save;
+
+       u64 *chunk_offsets = NULL;
+       u8 *ubuf = NULL;
+       void *cbuf = NULL;
+       bool chunk_offsets_malloced = false;
+       bool ubuf_malloced = false;
+       bool cbuf_malloced = false;
+       struct wimlib_decompressor *decompressor = NULL;
+
+       /* Sanity checks  */
+       wimlib_assert(rspec != NULL);
+       wimlib_assert(resource_is_compressed(rspec));
+       wimlib_assert(cb != NULL);
+       wimlib_assert(num_ranges != 0);
+       for (size_t i = 0; i < num_ranges; i++) {
+               DEBUG("Range %zu/%zu: %"PRIu64"@+%"PRIu64" / %"PRIu64,
+                     i + 1, num_ranges, ranges[i].size, ranges[i].offset,
+                     rspec->uncompressed_size);
+               wimlib_assert(ranges[i].size != 0);
+               wimlib_assert(ranges[i].offset + ranges[i].size >= ranges[i].size);
+               wimlib_assert(ranges[i].offset + ranges[i].size <= rspec->uncompressed_size);
+       }
+       for (size_t i = 0; i < num_ranges - 1; i++)
+               wimlib_assert(ranges[i].offset + ranges[i].size <= ranges[i + 1].offset);
+
+       /* Get the offsets of the first and last bytes of the read.  */
+       const u64 first_offset = ranges[0].offset;
+       const u64 last_offset = ranges[num_ranges - 1].offset + ranges[num_ranges - 1].size - 1;
+
+       /* Get the file descriptor for the WIM.  */
+       struct filedes * const in_fd = &rspec->wim->in_fd;
+
+       /* Determine if we're reading a pipable resource from a pipe or not.  */
+       const bool is_pipe_read = !filedes_is_seekable(in_fd);
+
+       /* Determine if the chunk table is in an altenate format.  */
+       const bool alt_chunk_table = (rspec->flags & WIM_RESHDR_FLAG_PACKED_STREAMS)
+                                       && !is_pipe_read;
+
+       /* Get the maximum size of uncompressed chunks in this resource, which
+        * we require be a power of 2.  */
+       u32 chunk_size;
+       u64 cur_read_offset = rspec->offset_in_wim;
+       int ctype;
+       if (alt_chunk_table) {
+               /* Alternate chunk table format.  Its header specifies the chunk
+                * size and compression format.  */
+               struct alt_chunk_table_header_disk hdr;
+
+               ret = full_pread(in_fd, &hdr, sizeof(hdr), cur_read_offset);
+               if (ret)
+                       goto read_error;
+               cur_read_offset += sizeof(hdr);
 
-       /* Trivial case */
-       if (len == 0)
-               return 0;
+               chunk_size = le32_to_cpu(hdr.chunk_size);
+               ctype = le32_to_cpu(hdr.compression_format);
 
-       int (*decompress)(const void *, unsigned, void *, unsigned);
-       /* Set the appropriate decompress function. */
-       if (resource_ctype == WIMLIB_COMPRESSION_TYPE_LZX)
-               decompress = wimlib_lzx_decompress;
-       else
-               decompress = wimlib_xpress_decompress;
-
-       /* The structure of a compressed resource consists of a table of chunk
-        * offsets followed by the chunks themselves.  Each chunk consists of
-        * compressed data, and there is one chunk for each WIM_CHUNK_SIZE =
-        * 32768 bytes of the uncompressed file, with the last chunk having any
-        * remaining bytes.
-        *
-        * 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.
-        */
-
-       /* Calculate how many chunks the resource consists of in its entirety.
-        * */
-       u64 num_chunks = (resource_uncompressed_size + WIM_CHUNK_SIZE - 1) /
-                                                               WIM_CHUNK_SIZE;
-       /* As mentioned, the first chunk has no entry in the chunk table. */
-       u64 num_chunk_entries = num_chunks - 1;
-
-
-       /* The index of the chunk that the read starts at. */
-       u64 start_chunk = offset / WIM_CHUNK_SIZE;
-       /* The byte offset at which the read starts, within the start chunk. */
-       u64 start_chunk_offset = offset % WIM_CHUNK_SIZE;
-
-       /* The index of the chunk that contains the last byte of the read. */
-       u64 end_chunk   = (offset + len - 1) / WIM_CHUNK_SIZE;
-       /* The byte offset of the last byte of the read, within the end chunk */
-       u64 end_chunk_offset = (offset + len - 1) % WIM_CHUNK_SIZE;
-
-       /* Number of chunks that are actually needed to read the requested part
-        * of the file. */
-       u64 num_needed_chunks = end_chunk - start_chunk + 1;
-
-       /* If the end chunk is not the last chunk, an extra chunk entry is
-        * needed because we need to know the offset of the chunk after the last
-        * chunk read to figure out the size of the last read chunk. */
-       if (end_chunk != num_chunks - 1)
-               num_needed_chunks++;
-
-       /* Allocate the chunk table.  It will only contain offsets for the
-        * chunks that are actually needed for this read. */
-       u64 *chunk_offsets;
-       bool chunk_offsets_malloced;
-       if (num_needed_chunks < 1000) {
-               chunk_offsets = alloca(num_needed_chunks * sizeof(u64));
-               chunk_offsets_malloced = false;
+               /* Format numbers must be the same as in WIMGAPI to be
+                * compatible.  */
+               BUILD_BUG_ON(WIMLIB_COMPRESSION_TYPE_NONE != 0);
+               BUILD_BUG_ON(WIMLIB_COMPRESSION_TYPE_LZX != 1);
+               BUILD_BUG_ON(WIMLIB_COMPRESSION_TYPE_XPRESS != 2);
+               BUILD_BUG_ON(WIMLIB_COMPRESSION_TYPE_LZMS != 3);
        } else {
-               chunk_offsets = malloc(num_needed_chunks * sizeof(u64));
-               if (!chunk_offsets) {
-                       ERROR("Failed to allocate chunk table "
-                             "with %"PRIu64" entries", num_needed_chunks);
-                       return WIMLIB_ERR_NOMEM;
-               }
-               chunk_offsets_malloced = true;
+               /* "Normal" format: the maximum uncompressed chunk size and the
+                * compression format default to those of the WIM itself.  */
+               chunk_size = rspec->wim->chunk_size;
+               ctype = rspec->wim->compression_type;
+       }
+       if (!is_power_of_2(chunk_size)) {
+               ERROR("Invalid compressed resource: "
+                     "expected power-of-2 chunk size (got %u)", chunk_size);
+               ret = WIMLIB_ERR_INVALID_CHUNK_SIZE;
+               goto out_free_memory;
        }
 
-       /* Set the implicit offset of the first chunk if it is included in the
-        * needed chunks.
-        *
-        * Note: M$'s documentation includes a picture that shows the first
-        * chunk starting right after the chunk entry table, labeled as offset
-        * 0x10.  However, in the actual file format, the offset is measured
-        * from the end of the chunk entry table, so the first chunk has an
-        * offset of 0. */
-       if (start_chunk == 0)
-               chunk_offsets[0] = 0;
-
-       /* According to M$'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) ?
-                                                                       8 : 4;
-
-       /* Size of the full chunk table in the WIM file. */
-       u64 chunk_table_size = chunk_entry_size * num_chunk_entries;
-
-       /* Read the needed chunk offsets from the table in the WIM file. */
-
-       /* Index, in the WIM file, of the first needed entry in the
-        * chunk table. */
-       u64 start_table_idx = (start_chunk == 0) ? 0 : start_chunk - 1;
-
-       /* 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) ?
-                               num_needed_chunks - 1 : num_needed_chunks;
-
-       /* Skip over unneeded chunk table entries. */
-       u64 file_offset_of_needed_chunk_entries = resource_offset +
-                               start_table_idx * chunk_entry_size;
-
-       /* Number of bytes we need to read from the chunk table. */
-       size_t size = num_needed_chunk_entries * chunk_entry_size;
-
-       /* Read the raw data into the end of the chunk_offsets array to
-        * avoid allocating another array. */
-       void *chunk_tab_buf = (void*)&chunk_offsets[num_needed_chunks] - size;
-
-       if (full_pread(in_fd, chunk_tab_buf, size,
-                      file_offset_of_needed_chunk_entries) != size)
-               goto read_error;
-
-       /* Now fill in chunk_offsets from the entries we have read in
-        * chunk_tab_buf. */
-
-       u64 *chunk_tab_p = chunk_offsets;
-       if (start_chunk == 0)
-               chunk_tab_p++;
-
-       if (chunk_entry_size == 4) {
-               u32 *entries = (u32*)chunk_tab_buf;
-               while (num_needed_chunk_entries--)
-                       *chunk_tab_p++ = le32_to_cpu(*entries++);
+       /* Get valid decompressor.  */
+       if (ctype == rspec->wim->decompressor_ctype &&
+           chunk_size == rspec->wim->decompressor_max_block_size)
+       {
+               /* Cached decompressor.  */
+               decompressor = rspec->wim->decompressor;
+               rspec->wim->decompressor_ctype = WIMLIB_COMPRESSION_TYPE_NONE;
+               rspec->wim->decompressor = NULL;
        } else {
-               u64 *entries = (u64*)chunk_tab_buf;
-               while (num_needed_chunk_entries--)
-                       *chunk_tab_p++ = le64_to_cpu(*entries++);
+               ret = wimlib_create_decompressor(ctype, chunk_size, NULL,
+                                                &decompressor);
+               if (ret)
+                       goto out_free_memory;
        }
 
-       /* Done with the chunk table now.  We must now seek to the first chunk
-        * that is needed for the read. */
+       const u32 chunk_order = bsr32(chunk_size);
+
+       /* Calculate the total number of chunks the resource is divided into.  */
+       const u64 num_chunks = (rspec->uncompressed_size + chunk_size - 1) >> chunk_order;
+
+       /* Calculate the 0-based indices of the first and last chunks containing
+        * data that needs to be passed to the callback.  */
+       const u64 first_needed_chunk = first_offset >> chunk_order;
+       const u64 last_needed_chunk = last_offset >> chunk_order;
+
+       /* Calculate the 0-based index of the first chunk that actually needs to
+        * be read.  This is normally first_needed_chunk, but for pipe reads we
+        * must always start from the 0th chunk.  */
+       const u64 read_start_chunk = (is_pipe_read ? 0 : first_needed_chunk);
+
+       /* Calculate the number of chunk offsets that are needed for the chunks
+        * being read.  */
+       const u64 num_needed_chunk_offsets =
+               last_needed_chunk - read_start_chunk + 1 +
+               (last_needed_chunk < num_chunks - 1);
+
+       /* Calculate the number of entries in the chunk table.  Normally, it's
+        * one less than the number of chunks, since the first chunk has no
+        * entry.  But in the alternate chunk table format, the chunk entries
+        * contain chunk sizes, not offsets, and there is one per chunk.  */
+       const u64 num_chunk_entries = (alt_chunk_table ? num_chunks : num_chunks - 1);
+
+       /* Set the size of each chunk table entry based on the resource's
+        * uncompressed size.  XXX:  Does the alternate chunk table really
+        * always have 4-byte entries?  */
+       const u64 chunk_entry_size =
+               (rspec->uncompressed_size > (1ULL << 32) && !alt_chunk_table)
+                       ? 8 : 4;
+
+       /* Calculate the size of the chunk table in bytes.  */
+       const u64 chunk_table_size = num_chunk_entries * chunk_entry_size;
+
+       /* Calculate the size of the chunk table in bytes, including the header
+        * in the case of the alternate chunk table format.  */
+       const u64 chunk_table_full_size =
+               (alt_chunk_table) ? chunk_table_size + sizeof(struct alt_chunk_table_header_disk)
+                                 : chunk_table_size;
+
+       if (!is_pipe_read) {
+               /* Read the needed chunk table entries into memory and use them
+                * to initialize the chunk_offsets array.  */
+
+               u64 first_chunk_entry_to_read;
+               u64 last_chunk_entry_to_read;
+
+               if (alt_chunk_table) {
+                       /* The alternate chunk table contains chunk sizes, not
+                        * offsets, so we always must read all preceding entries
+                        * in order to determine offsets.  */
+                       first_chunk_entry_to_read = 0;
+                       last_chunk_entry_to_read = last_needed_chunk;
+               } else {
+                       /* Here we must account for the fact that the first
+                        * chunk has no explicit chunk table entry.  */
 
-       u64 cur_read_offset = resource_offset + chunk_table_size + chunk_offsets[0];
+                       if (read_start_chunk == 0)
+                               first_chunk_entry_to_read = 0;
+                       else
+                               first_chunk_entry_to_read = read_start_chunk - 1;
 
-       /* Pointer to current position in the output buffer for uncompressed
-        * data.  Alternatively, if using a callback function, we repeatedly
-        * fill a temporary buffer to feed data into the callback function.  */
-       u8 *out_p;
-       if (cb)
-               out_p = alloca(WIM_CHUNK_SIZE);
-       else
-               out_p = ctx_or_buf;
-
-       /* 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
-        * size in the worst-case.  This assumption is valid only if chunks that
-        * happen to compress to more than the uncompressed size (i.e. a
-        * sequence of random bytes) are always stored uncompressed. But this seems
-        * to be the case in M$'s WIM files, even though it is undocumented. */
-       void *compressed_buf = alloca(WIM_CHUNK_SIZE - 1);
-
-       /* Decompress all the chunks. */
-       for (u64 i = start_chunk; i <= end_chunk; i++) {
-
-               /* Calculate the sizes of the compressed chunk and of the
-                * uncompressed chunk. */
-               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] -
-                                               chunk_offsets[i - start_chunk];
-                       uncompressed_chunk_size = WIM_CHUNK_SIZE;
+                       if (last_needed_chunk == 0)
+                               last_chunk_entry_to_read = 0;
+                       else
+                               last_chunk_entry_to_read = last_needed_chunk - 1;
+
+                       if (last_needed_chunk < num_chunks - 1)
+                               last_chunk_entry_to_read++;
+               }
+
+               const u64 num_chunk_entries_to_read =
+                       last_chunk_entry_to_read - first_chunk_entry_to_read + 1;
+
+               const u64 chunk_offsets_alloc_size =
+                       max(num_chunk_entries_to_read,
+                           num_needed_chunk_offsets) * sizeof(chunk_offsets[0]);
+
+               if ((size_t)chunk_offsets_alloc_size != chunk_offsets_alloc_size)
+                       goto oom;
+
+               if (chunk_offsets_alloc_size <= STACK_MAX) {
+                       chunk_offsets = alloca(chunk_offsets_alloc_size);
+               } else {
+                       chunk_offsets = MALLOC(chunk_offsets_alloc_size);
+                       if (chunk_offsets == NULL)
+                               goto oom;
+                       chunk_offsets_malloced = true;
+               }
+
+               const size_t chunk_table_size_to_read =
+                       num_chunk_entries_to_read * chunk_entry_size;
+
+               const u64 file_offset_of_needed_chunk_entries =
+                       cur_read_offset
+                       + (first_chunk_entry_to_read * chunk_entry_size)
+                       + (rspec->is_pipable ? (rspec->size_in_wim - chunk_table_size) : 0);
+
+               void * const chunk_table_data =
+                       (u8*)chunk_offsets +
+                       chunk_offsets_alloc_size -
+                       chunk_table_size_to_read;
+
+               ret = full_pread(in_fd, chunk_table_data, chunk_table_size_to_read,
+                                file_offset_of_needed_chunk_entries);
+               if (ret)
+                       goto read_error;
+
+               /* Now fill in chunk_offsets from the entries we have read in
+                * chunk_tab_data.  We break aliasing rules here to avoid having
+                * to allocate yet another array.  */
+               typedef le64 __attribute__((may_alias)) aliased_le64_t;
+               typedef le32 __attribute__((may_alias)) aliased_le32_t;
+               u64 * chunk_offsets_p = chunk_offsets;
+
+               if (alt_chunk_table) {
+                       u64 cur_offset = 0;
+                       aliased_le32_t *raw_entries = chunk_table_data;
+
+                       for (size_t i = 0; i < num_chunk_entries_to_read; i++) {
+                               u32 entry = le32_to_cpu(raw_entries[i]);
+                               if (i >= read_start_chunk)
+                                       *chunk_offsets_p++ = cur_offset;
+                               cur_offset += entry;
+                       }
+                       if (last_needed_chunk < num_chunks - 1)
+                               *chunk_offsets_p = cur_offset;
                } else {
-                       /* The last compressed chunk consists of the remaining
-                        * 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.
-                        *
-                        * Note that the resource_compressed_size includes the
-                        * chunk table, so the size of it must be subtracted. */
-                       compressed_chunk_size = resource_compressed_size -
-                                               chunk_table_size -
-                                               chunk_offsets[i - start_chunk];
-
-                       uncompressed_chunk_size = resource_uncompressed_size %
-                                                               WIM_CHUNK_SIZE;
-
-                       /* If the remainder is 0, the last chunk actually
-                        * uncompresses to a full WIM_CHUNK_SIZE bytes. */
-                       if (uncompressed_chunk_size == 0)
-                               uncompressed_chunk_size = WIM_CHUNK_SIZE;
+                       if (read_start_chunk == 0)
+                               *chunk_offsets_p++ = 0;
+
+                       if (chunk_entry_size == 4) {
+                               aliased_le32_t *raw_entries = chunk_table_data;
+                               for (size_t i = 0; i < num_chunk_entries_to_read; i++)
+                                       *chunk_offsets_p++ = le32_to_cpu(raw_entries[i]);
+                       } else {
+                               aliased_le64_t *raw_entries = chunk_table_data;
+                               for (size_t i = 0; i < num_chunk_entries_to_read; i++)
+                                       *chunk_offsets_p++ = le64_to_cpu(raw_entries[i]);
+                       }
                }
 
-               /* Figure out how much of this chunk we actually need to read */
-               u64 start_offset;
-               if (i == start_chunk)
-                       start_offset = start_chunk_offset;
+               /* Set offset to beginning of first chunk to read.  */
+               cur_read_offset += chunk_offsets[0];
+               if (rspec->is_pipable)
+                       cur_read_offset += read_start_chunk * sizeof(struct pwm_chunk_hdr);
                else
-                       start_offset = 0;
-               u64 end_offset;
-               if (i == end_chunk)
-                       end_offset = end_chunk_offset;
+                       cur_read_offset += chunk_table_size;
+       }
+
+       /* Allocate buffer for holding the uncompressed data of each chunk.  */
+       if (chunk_size <= STACK_MAX) {
+               ubuf = alloca(chunk_size);
+       } else {
+               ubuf = MALLOC(chunk_size);
+               if (ubuf == NULL)
+                       goto oom;
+               ubuf_malloced = true;
+       }
+
+       /* Allocate a temporary buffer for reading compressed chunks, each of
+        * which can be at most @chunk_size - 1 bytes.  This excludes compressed
+        * chunks that are a full @chunk_size bytes, which are actually stored
+        * uncompressed.  */
+       if (chunk_size - 1 <= STACK_MAX) {
+               cbuf = alloca(chunk_size - 1);
+       } else {
+               cbuf = MALLOC(chunk_size - 1);
+               if (cbuf == NULL)
+                       goto oom;
+               cbuf_malloced = true;
+       }
+
+       /* Set current data range.  */
+       const struct data_range *cur_range = ranges;
+       const struct data_range * const end_range = &ranges[num_ranges];
+       u64 cur_range_pos = cur_range->offset;
+       u64 cur_range_end = cur_range->offset + cur_range->size;
+
+       /* Read and process each needed chunk.  */
+       for (u64 i = read_start_chunk; i <= last_needed_chunk; i++) {
+
+               /* Calculate uncompressed size of next chunk.  */
+               u32 chunk_usize;
+               if ((i == num_chunks - 1) && (rspec->uncompressed_size & (chunk_size - 1)))
+                       chunk_usize = (rspec->uncompressed_size & (chunk_size - 1));
                else
-                       end_offset = WIM_CHUNK_SIZE - 1;
-
-               unsigned partial_chunk_size = end_offset + 1 - start_offset;
-               bool is_partial_chunk = (partial_chunk_size != uncompressed_chunk_size);
-
-               /* This is undocumented, but chunks can be uncompressed.  This
-                * appears to always be the case when the compressed chunk size
-                * is equal to the uncompressed chunk size. */
-               if (compressed_chunk_size == uncompressed_chunk_size) {
-                       /* Uncompressed chunk */
-                       if (full_pread(in_fd,
-                                      cb ? out_p + start_offset : out_p,
-                                      partial_chunk_size,
-                                      cur_read_offset + start_offset) != partial_chunk_size)
-                       {
+                       chunk_usize = chunk_size;
+
+               /* Calculate compressed size of next chunk.  */
+               u32 chunk_csize;
+               if (is_pipe_read) {
+                       struct pwm_chunk_hdr chunk_hdr;
+
+                       ret = full_pread(in_fd, &chunk_hdr,
+                                        sizeof(chunk_hdr), cur_read_offset);
+                       if (ret)
                                goto read_error;
-                       }
+                       chunk_csize = le32_to_cpu(chunk_hdr.compressed_size);
                } else {
-                       /* Compressed chunk */
+                       if (i == num_chunks - 1) {
+                               chunk_csize = rspec->size_in_wim -
+                                             chunk_table_full_size -
+                                             chunk_offsets[i - read_start_chunk];
+                               if (rspec->is_pipable)
+                                       chunk_csize -= num_chunks * sizeof(struct pwm_chunk_hdr);
+                       } else {
+                               chunk_csize = chunk_offsets[i + 1 - read_start_chunk] -
+                                             chunk_offsets[i - read_start_chunk];
+                       }
+               }
+               if (chunk_csize == 0 || chunk_csize > chunk_usize) {
+                       ERROR("Invalid chunk size in compressed resource!");
+                       errno = EINVAL;
+                       ret = WIMLIB_ERR_DECOMPRESSION;
+                       goto out_free_memory;
+               }
+               if (rspec->is_pipable)
+                       cur_read_offset += sizeof(struct pwm_chunk_hdr);
 
-                       /* Read the compressed data into compressed_buf. */
-                       if (full_pread(in_fd,
-                                      compressed_buf,
-                                      compressed_chunk_size,
-                                      cur_read_offset) != compressed_chunk_size)
-                       {
-                               goto read_error;
+               /* Offsets in the uncompressed resource at which this chunk
+                * starts and ends.  */
+               const u64 chunk_start_offset = i << chunk_order;
+               const u64 chunk_end_offset = chunk_start_offset + chunk_usize;
+
+               if (chunk_end_offset <= cur_range_pos) {
+
+                       /* The next range does not require data in this chunk,
+                        * so skip it.  */
+                       cur_read_offset += chunk_csize;
+                       if (is_pipe_read) {
+                               u8 dummy;
+
+                               ret = full_pread(in_fd, &dummy, 1, cur_read_offset - 1);
+                               if (ret)
+                                       goto read_error;
                        }
+               } else {
 
-                       /* For partial chunks and when writing directly to a
-                        * buffer, we must buffer the uncompressed data because
-                        * we don't need all of it. */
-                       if (is_partial_chunk && !cb) {
-                               u8 uncompressed_buf[uncompressed_chunk_size];
+                       /* Read the chunk and feed data to the callback
+                        * function.  */
+                       u8 *read_buf;
 
-                               ret = decompress(compressed_buf,
-                                                compressed_chunk_size,
-                                                uncompressed_buf,
-                                                uncompressed_chunk_size);
-                               if (ret) {
-                                       ret = WIMLIB_ERR_DECOMPRESSION;
-                                       goto out;
-                               }
-                               memcpy(out_p, uncompressed_buf + start_offset,
-                                      partial_chunk_size);
-                       } else {
-                               ret = decompress(compressed_buf,
-                                                compressed_chunk_size,
-                                                out_p,
-                                                uncompressed_chunk_size);
+                       if (chunk_csize == chunk_usize)
+                               read_buf = ubuf;
+                       else
+                               read_buf = cbuf;
+
+                       ret = full_pread(in_fd,
+                                        read_buf,
+                                        chunk_csize,
+                                        cur_read_offset);
+                       if (ret)
+                               goto read_error;
+
+                       if (read_buf == cbuf) {
+                               DEBUG("Decompressing chunk %"PRIu64" "
+                                     "(csize=%"PRIu32" usize=%"PRIu32")",
+                                     i, chunk_csize, chunk_usize);
+                               ret = wimlib_decompress(cbuf,
+                                                       chunk_csize,
+                                                       ubuf,
+                                                       chunk_usize,
+                                                       decompressor);
                                if (ret) {
+                                       ERROR("Failed to decompress data!");
                                        ret = WIMLIB_ERR_DECOMPRESSION;
-                                       goto out;
+                                       errno = EINVAL;
+                                       goto out_free_memory;
                                }
                        }
+                       cur_read_offset += chunk_csize;
+
+                       /* At least one range requires data in this chunk.  */
+                       do {
+                               size_t start, end, size;
+
+                               /* Calculate how many bytes of data should be
+                                * sent to the callback function, taking into
+                                * account that data sent to the callback
+                                * function must not overlap range boundaries.
+                                */
+                               start = cur_range_pos - chunk_start_offset;
+                               end = min(cur_range_end, chunk_end_offset) - chunk_start_offset;
+                               size = end - start;
+
+                               ret = (*cb)(&ubuf[start], size, cb_ctx);
+
+                               if (ret)
+                                       goto out_free_memory;
+
+                               cur_range_pos += size;
+                               if (cur_range_pos == cur_range_end) {
+                                       /* Advance to next range.  */
+                                       if (++cur_range == end_range) {
+                                               cur_range_pos = ~0ULL;
+                                       } else {
+                                               cur_range_pos = cur_range->offset;
+                                               cur_range_end = cur_range->offset + cur_range->size;
+                                       }
+                               }
+                       } while (cur_range_pos < chunk_end_offset);
                }
-               if (cb) {
-                       /* Feed the data to the callback function */
-                       ret = cb(out_p + start_offset,
-                                partial_chunk_size, ctx_or_buf);
-                       if (ret)
-                               goto out;
-               } else {
-                       /* No callback function provided; we are writing
-                        * directly to a buffer.  Advance the pointer into this
-                        * buffer by the number of uncompressed bytes that were
-                        * written.  */
-                       out_p += partial_chunk_size;
-               }
-               cur_read_offset += compressed_chunk_size;
        }
 
+       if (is_pipe_read &&
+           last_offset == rspec->uncompressed_size - 1 &&
+           chunk_table_size)
+       {
+               u8 dummy;
+               /* If reading a pipable resource from a pipe and the full data
+                * was requested, skip the chunk table at the end so that the
+                * file descriptor is fully clear of the resource after this
+                * returns.  */
+               cur_read_offset += chunk_table_size;
+               ret = full_pread(in_fd, &dummy, 1, cur_read_offset - 1);
+               if (ret)
+                       goto read_error;
+       }
        ret = 0;
-out:
+
+out_free_memory:
+       errno_save = errno;
+       if (decompressor) {
+               wimlib_free_decompressor(rspec->wim->decompressor);
+               rspec->wim->decompressor = decompressor;
+               rspec->wim->decompressor_ctype = ctype;
+               rspec->wim->decompressor_max_block_size = chunk_size;
+       }
        if (chunk_offsets_malloced)
                FREE(chunk_offsets);
+       if (ubuf_malloced)
+               FREE(ubuf);
+       if (cbuf_malloced)
+               FREE(cbuf);
+       errno = errno_save;
        return ret;
 
+oom:
+       ERROR("Not enough memory available to read size=%"PRIu64" bytes "
+             "from compressed WIM resource!", last_offset - first_offset + 1);
+       errno = ENOMEM;
+       ret = WIMLIB_ERR_NOMEM;
+       goto out_free_memory;
+
 read_error:
-       ERROR_WITH_ERRNO("Error reading compressed file resource");
-       ret = WIMLIB_ERR_READ;
-       goto out;
+       ERROR_WITH_ERRNO("Error reading compressed WIM resource!");
+       goto out_free_memory;
 }
 
-/* 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 void *
-get_resource_entry(const void *p, struct resource_entry *entry)
+/* Read raw data from a file descriptor at the specified offset, feeding the
+ * data it in chunks into the specified callback function.  */
+static int
+read_raw_file_data(struct filedes *in_fd, u64 offset, u64 size,
+                  consume_data_callback_t cb, void *cb_ctx)
 {
-       u64 size;
-       u8 flags;
-
-       p = get_u56(p, &size);
-       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;
+       u8 buf[BUFFER_SIZE];
+       size_t bytes_to_read;
+       int ret;
+
+       while (size) {
+               bytes_to_read = min(sizeof(buf), size);
+               ret = full_pread(in_fd, buf, bytes_to_read, offset);
+               if (ret) {
+                       ERROR_WITH_ERRNO("Read error");
+                       return ret;
+               }
+               ret = cb(buf, bytes_to_read, cb_ctx);
+               if (ret)
+                       return ret;
+               size -= bytes_to_read;
+               offset += bytes_to_read;
        }
-       return p;
+       return 0;
 }
 
-/* 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. */
-void *
-put_resource_entry(void *p, const struct resource_entry *entry)
+/* A consume_data_callback_t implementation that simply concatenates all chunks
+ * into a buffer.  */
+static int
+bufferer_cb(const void *chunk, size_t size, void *_ctx)
 {
-       p = put_u56(p, entry->size);
-       p = put_u8(p, entry->flags);
-       p = put_u64(p, entry->offset);
-       p = put_u64(p, entry->original_size);
-       return p;
+       u8 **buf_p = _ctx;
+
+       *buf_p = mempcpy(*buf_p, chunk, size);
+       return 0;
 }
 
+/*
+ * read_partial_wim_resource()-
+ *
+ * Read a range of data from an uncompressed or compressed resource in a WIM
+ * file.
+ *
+ * @rspec
+ *     Specification of the WIM resource to read from.
+ * @offset
+ *     Offset within the uncompressed resource at which to start reading.
+ * @size
+ *     Number of bytes to read.
+ * @cb
+ *     Callback function to feed the data being read.  Each call provides the
+ *     next chunk of the requested data, uncompressed.  Each chunk will be of
+ *     nonzero size and will not cross range boundaries, but otherwise will be
+ *     of unspecified size.
+ * @cb_ctx
+ *     Parameter to pass to @cb_ctx.
+ *
+ * Return values:
+ *     WIMLIB_ERR_SUCCESS (0)
+ *     WIMLIB_ERR_READ                   (errno set)
+ *     WIMLIB_ERR_UNEXPECTED_END_OF_FILE (errno set to 0)
+ *     WIMLIB_ERR_NOMEM                  (errno set to ENOMEM)
+ *     WIMLIB_ERR_DECOMPRESSION          (errno set to EINVAL)
+ *
+ *     or other error code returned by the @cb function.
+ */
 static int
-read_partial_wim_resource(const struct wim_lookup_table_entry *lte,
-                         u64 size,
-                         consume_data_callback_t cb,
-                         void *ctx_or_buf,
-                         int flags,
-                         u64 offset)
+read_partial_wim_resource(const struct wim_resource_spec *rspec,
+                         u64 offset, u64 size,
+                         consume_data_callback_t cb, void *cb_ctx)
 {
-       WIMStruct *wim;
-       int in_fd;
-       int ret;
+       /* Sanity checks.  */
+       wimlib_assert(offset + size >= offset);
+       wimlib_assert(offset + size <= rspec->uncompressed_size);
 
-       wimlib_assert(lte->resource_location == RESOURCE_IN_WIM);
+       DEBUG("Reading %"PRIu64" @ %"PRIu64" from WIM resource  "
+             "%"PRIu64" => %"PRIu64" @ %"PRIu64,
+             size, offset, rspec->uncompressed_size,
+             rspec->size_in_wim, rspec->offset_in_wim);
 
-       wim = lte->wim;
-       in_fd = wim->in_fd;
+       /* Trivial case.  */
+       if (size == 0)
+               return 0;
 
-       if (lte->resource_entry.flags & WIM_RESHDR_FLAG_COMPRESSED &&
-           !(flags & WIMLIB_RESOURCE_FLAG_RAW))
-       {
-               ret = read_compressed_resource(in_fd,
-                                              lte->resource_entry.size,
-                                              lte->resource_entry.original_size,
-                                              lte->resource_entry.offset,
-                                              wimlib_get_compression_type(wim),
-                                              size,
-                                              offset,
-                                              cb,
-                                              ctx_or_buf);
+       if (resource_is_compressed(rspec)) {
+               struct data_range range = {
+                       .offset = offset,
+                       .size = size,
+               };
+               return read_compressed_wim_resource(rspec, &range, 1,
+                                                   cb, cb_ctx);
        } else {
-               offset += lte->resource_entry.offset;
-               if (cb) {
-                       /* Send data to callback function */
-                       u8 buf[min(WIM_CHUNK_SIZE, size)];
-                       while (size) {
-                               size_t bytes_to_read = min(WIM_CHUNK_SIZE, size);
-                               size_t bytes_read = full_pread(in_fd, buf,
-                                                              bytes_to_read, offset);
-                               if (bytes_read != bytes_to_read)
-                                       goto read_error;
-                               ret = cb(buf, bytes_read, ctx_or_buf);
-                               if (ret)
-                                       goto out;
-                               size -= bytes_read;
-                               offset += bytes_read;
-                       }
-               } else {
-                       /* Send data directly to a buffer */
-                       if (full_pread(in_fd, ctx_or_buf, size, offset) != size)
-                               goto read_error;
-               }
-               ret = 0;
+               return read_raw_file_data(&rspec->wim->in_fd,
+                                         rspec->offset_in_wim + offset,
+                                         size,
+                                         cb,
+                                         cb_ctx);
        }
-       goto out;
-read_error:
-       ERROR_WITH_ERRNO("Error reading data from WIM");
-       ret = WIMLIB_ERR_READ;
-out:
-       if (ret) {
-               if (errno == 0)
-                       errno = EIO;
-       }
-       return ret;
 }
 
-
+/* Read the specified range of uncompressed data from the specified stream,
+ * which must be located into a WIM file, into the specified buffer.  */
 int
-read_partial_wim_resource_into_buf(const struct wim_lookup_table_entry *lte,
-                                  size_t size, u64 offset, void *buf)
+read_partial_wim_stream_into_buf(const struct wim_lookup_table_entry *lte,
+                                size_t size, u64 offset, void *_buf)
 {
-       return read_partial_wim_resource(lte, size, NULL, buf, 0, offset);
+       u8 *buf = _buf;
+
+       wimlib_assert(lte->resource_location == RESOURCE_IN_WIM);
+
+       return read_partial_wim_resource(lte->rspec,
+                                        lte->offset_in_res + offset,
+                                        size,
+                                        bufferer_cb,
+                                        &buf);
 }
 
+/* A consume_data_callback_t implementation that simply ignores the data
+ * received.  */
 static int
-read_wim_resource_prefix(const struct wim_lookup_table_entry *lte,
-                        u64 size,
-                        consume_data_callback_t cb,
-                        void *ctx_or_buf,
-                        int flags)
+skip_chunk_cb(const void *chunk, size_t size, void *_ctx)
 {
-       return read_partial_wim_resource(lte, size, cb, ctx_or_buf, flags, 0);
+       return 0;
 }
 
+/* Skip over the data of the specified stream, which must correspond to a full
+ * WIM resource.  */
+int
+skip_wim_stream(struct wim_lookup_table_entry *lte)
+{
+       wimlib_assert(lte->resource_location == RESOURCE_IN_WIM);
+       wimlib_assert(!(lte->flags & WIM_RESHDR_FLAG_PACKED_STREAMS));
+       DEBUG("Skipping stream (size=%"PRIu64")", lte->size);
+       return read_partial_wim_resource(lte->rspec,
+                                        0,
+                                        lte->rspec->uncompressed_size,
+                                        skip_chunk_cb,
+                                        NULL);
+}
+
+static int
+read_wim_stream_prefix(const struct wim_lookup_table_entry *lte, u64 size,
+                      consume_data_callback_t cb, void *cb_ctx)
+{
+       return read_partial_wim_resource(lte->rspec, lte->offset_in_res, size,
+                                        cb, cb_ctx);
+}
 
 #ifndef __WIN32__
+/* This function handles reading stream data that is located in an external
+ * file,  such as a file that has been added to the WIM image through execution
+ * of a wimlib_add_command.
+ *
+ * This assumes the file can be accessed using the standard POSIX open(),
+ * read(), and close().  On Windows this will not necessarily be the case (since
+ * the file may need FILE_FLAG_BACKUP_SEMANTICS to be opened, or the file may be
+ * encrypted), so Windows uses its own code for its equivalent case.  */
 static int
-read_file_on_disk_prefix(const struct wim_lookup_table_entry *lte,
-                        u64 size,
-                        consume_data_callback_t cb,
-                        void *ctx_or_buf,
-                        int _ignored_flags)
+read_file_on_disk_prefix(const struct wim_lookup_table_entry *lte, u64 size,
+                        consume_data_callback_t cb, void *cb_ctx)
 {
-       const tchar *filename = lte->file_on_disk;
        int ret;
-       int fd;
-       size_t bytes_read;
+       int raw_fd;
+       struct filedes fd;
+
+       wimlib_assert(size <= lte->size);
 
-       fd = open(filename, O_RDONLY);
-       if (fd < 0) {
-               ERROR_WITH_ERRNO("Can't open \"%"TS"\"", filename);
+       DEBUG("Reading %"PRIu64" bytes from \"%"TS"\"", size, lte->file_on_disk);
+
+       raw_fd = open(lte->file_on_disk, O_BINARY | O_RDONLY);
+       if (raw_fd < 0) {
+               ERROR_WITH_ERRNO("Can't open \"%"TS"\"", lte->file_on_disk);
                return WIMLIB_ERR_OPEN;
        }
-       if (cb) {
-               /* Send data to callback function */
-               u8 buf[min(WIM_CHUNK_SIZE, size)];
-               size_t bytes_to_read;
-               while (size) {
-                       bytes_to_read = min(WIM_CHUNK_SIZE, size);
-                       bytes_read = full_read(fd, buf, bytes_to_read);
-                       if (bytes_read != bytes_to_read)
-                               goto read_error;
-                       ret = cb(buf, bytes_read, ctx_or_buf);
-                       if (ret)
-                               goto out_close;
-                       size -= bytes_read;
-               }
-       } else {
-               /* Send data directly to a buffer */
-               bytes_read = full_read(fd, ctx_or_buf, size);
-               if (bytes_read != size)
-                       goto read_error;
-       }
-       ret = 0;
-       goto out_close;
-read_error:
-       ERROR_WITH_ERRNO("Error reading \"%"TS"\"", filename);
-       ret = WIMLIB_ERR_READ;
-out_close:
-       close(fd);
+       filedes_init(&fd, raw_fd);
+       ret = read_raw_file_data(&fd, 0, size, cb, cb_ctx);
+       filedes_close(&fd);
        return ret;
 }
 #endif /* !__WIN32__ */
 
+/* This function handles the trivial case of reading stream data that is, in
+ * fact, already located in an in-memory buffer.  */
 static int
 read_buffer_prefix(const struct wim_lookup_table_entry *lte,
-                  u64 size, consume_data_callback_t cb,
-                  void *ctx_or_buf, int _ignored_flags)
+                  u64 size, consume_data_callback_t cb, void *cb_ctx)
 {
-       const void *inbuf = lte->attached_buffer;
-       int ret;
-
-       if (cb) {
-               while (size) {
-                       size_t chunk_size = min(WIM_CHUNK_SIZE, size);
-                       ret = cb(inbuf, chunk_size, ctx_or_buf);
-                       if (ret)
-                               return ret;
-                       size -= chunk_size;
-                       inbuf += chunk_size;
-               }
-       } else {
-               memcpy(ctx_or_buf, inbuf, size);
-       }
-       return 0;
+       wimlib_assert(size <= lte->size);
+       return (*cb)(lte->attached_buffer, size, cb_ctx);
 }
 
-typedef int (*read_resource_prefix_handler_t)(const struct wim_lookup_table_entry *lte,
-                                             u64 size,
-                                             consume_data_callback_t cb,
-                                             void *ctx_or_buf,
-                                             int flags);
+typedef int (*read_stream_prefix_handler_t)(const struct wim_lookup_table_entry *lte,
+                                           u64 size,
+                                           consume_data_callback_t cb,
+                                           void *cb_ctx);
 
 /*
- * Read the first @size bytes from a generic "resource", which may be located in
- * the WIM (compressed or uncompressed), in an external file, or directly in an
- * in-memory buffer.
- *
- * Feed the data either to a callback function (cb != NULL, passing it
- * ctx_or_buf), or write it directly into a buffer (cb == NULL, ctx_or_buf
- * specifies the buffer, which must have room for @size bytes).
- *
- * When using a callback function, it is called with chunks up to 32768 bytes in
- * size until the resource is exhausted.
- *
- * If the resource is located in a WIM file, @flags can be:
- *   * WIMLIB_RESOURCE_FLAG_THREADSAFE_READ if it must be safe to access the resource
- *     concurrently by multiple threads.
- *   * WIMLIB_RESOURCE_FLAG_RAW if the raw compressed data is to be supplied
- *     instead of the uncompressed data.
- * Otherwise, the @flags are ignored.
+ * read_stream_prefix()-
+ *
+ * Reads the first @size bytes from a generic "stream", which may be located in
+ * any one of several locations, such as in a WIM file (compressed or
+ * uncompressed), in an external file, or directly in an in-memory buffer.
+ *
+ * This function feeds the data to a callback function @cb in chunks of
+ * unspecified size.
+ *
+ * Returns 0 on success; nonzero on error.  A nonzero value will be returned if
+ * the stream data cannot be successfully read (for a number of different
+ * reasons, depending on the stream location), or if @cb returned nonzero in
+ * which case that error code will be returned.
  */
-int
-read_resource_prefix(const struct wim_lookup_table_entry *lte,
-                    u64 size, consume_data_callback_t cb, void *ctx_or_buf,
-                    int flags)
+static int
+read_stream_prefix(const struct wim_lookup_table_entry *lte, u64 size,
+                  consume_data_callback_t cb, void *cb_ctx)
 {
-       static const read_resource_prefix_handler_t handlers[] = {
-               [RESOURCE_IN_WIM]             = read_wim_resource_prefix,
-       #ifndef __WIN32__
+       static const read_stream_prefix_handler_t handlers[] = {
+               [RESOURCE_IN_WIM]             = read_wim_stream_prefix,
+       #ifdef __WIN32__
+               [RESOURCE_IN_FILE_ON_DISK]    = read_win32_file_prefix,
+       #else
                [RESOURCE_IN_FILE_ON_DISK]    = read_file_on_disk_prefix,
        #endif
                [RESOURCE_IN_ATTACHED_BUFFER] = read_buffer_prefix,
@@ -587,147 +808,589 @@ read_resource_prefix(const struct wim_lookup_table_entry *lte,
                [RESOURCE_IN_NTFS_VOLUME]     = read_ntfs_file_prefix,
        #endif
        #ifdef __WIN32__
-               [RESOURCE_WIN32]              = read_win32_file_prefix,
                [RESOURCE_WIN32_ENCRYPTED]    = read_win32_encrypted_file_prefix,
        #endif
        };
        wimlib_assert(lte->resource_location < ARRAY_LEN(handlers)
                      && handlers[lte->resource_location] != NULL);
-       return handlers[lte->resource_location](lte, size, cb, ctx_or_buf, flags);
+       return handlers[lte->resource_location](lte, size, cb, cb_ctx);
 }
 
+/* Read the full uncompressed data of the specified stream into the specified
+ * buffer, which must have space for at least lte->size bytes.  */
 int
-read_full_resource_into_buf(const struct wim_lookup_table_entry *lte,
-                           void *buf)
+read_full_stream_into_buf(const struct wim_lookup_table_entry *lte, void *_buf)
 {
-       return read_resource_prefix(lte, wim_resource_size(lte), NULL, buf, 0);
+       u8 *buf = _buf;
+       return read_stream_prefix(lte, lte->size, bufferer_cb, &buf);
 }
 
-struct extract_ctx {
-       SHA_CTX sha_ctx;
-       consume_data_callback_t extract_chunk;
-       void *extract_chunk_arg;
-};
+/* Retrieve the full uncompressed data of the specified stream.  A buffer large
+ * enough hold the data is allocated and returned in @buf_ret.  */
+int
+read_full_stream_into_alloc_buf(const struct wim_lookup_table_entry *lte,
+                               void **buf_ret)
+{
+       int ret;
+       void *buf;
+
+       if ((size_t)lte->size != lte->size) {
+               ERROR("Can't read %"PRIu64" byte stream into "
+                     "memory", lte->size);
+               return WIMLIB_ERR_NOMEM;
+       }
 
+       buf = MALLOC(lte->size);
+       if (buf == NULL)
+               return WIMLIB_ERR_NOMEM;
+
+       ret = read_full_stream_into_buf(lte, buf);
+       if (ret) {
+               FREE(buf);
+               return ret;
+       }
+
+       *buf_ret = buf;
+       return 0;
+}
+
+/* Retrieve the full uncompressed data of the specified WIM resource.  A buffer
+ * large enough hold the data is allocated and returned in @buf_ret.  */
 static int
-extract_chunk_sha1_wrapper(const void *chunk, size_t chunk_size,
-                          void *_ctx)
+wim_resource_spec_to_data(struct wim_resource_spec *rspec, void **buf_ret)
 {
-       struct extract_ctx *ctx = _ctx;
+       int ret;
+       struct wim_lookup_table_entry *lte;
+
+       lte = new_lookup_table_entry();
+       if (lte == NULL)
+               return WIMLIB_ERR_NOMEM;
+
+       lte_bind_wim_resource_spec(lte, rspec);
+       lte->flags = rspec->flags;
+       lte->size = rspec->uncompressed_size;
+       lte->offset_in_res = 0;
 
-       sha1_update(&ctx->sha_ctx, chunk, chunk_size);
-       return ctx->extract_chunk(chunk, chunk_size, ctx->extract_chunk_arg);
+       ret = read_full_stream_into_alloc_buf(lte, buf_ret);
+
+       lte_unbind_wim_resource_spec(lte);
+       free_lookup_table_entry(lte);
+       return ret;
 }
 
-/* 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.
- *
- * @extract_chunk is a function that is called to extract each chunk of the
- * resource. */
+/* Retrieve the full uncompressed data of a WIM resource specified as a raw
+ * `wim_reshdr' and the corresponding WIM file.  A large enough hold the data is
+ * allocated and returned in @buf_ret.  */
 int
-extract_wim_resource(const struct wim_lookup_table_entry *lte,
-                    u64 size,
-                    consume_data_callback_t extract_chunk,
-                    void *extract_chunk_arg)
+wim_reshdr_to_data(const struct wim_reshdr *reshdr, WIMStruct *wim, void **buf_ret)
+{
+       DEBUG("offset_in_wim=%"PRIu64", size_in_wim=%"PRIu64", "
+             "uncompressed_size=%"PRIu64,
+             reshdr->offset_in_wim, reshdr->size_in_wim,
+             reshdr->uncompressed_size);
+
+       struct wim_resource_spec rspec;
+       wim_res_hdr_to_spec(reshdr, wim, &rspec);
+       return wim_resource_spec_to_data(&rspec, buf_ret);
+}
+
+struct streamifier_context {
+       struct read_stream_list_callbacks cbs;
+       struct wim_lookup_table_entry *cur_stream;
+       struct wim_lookup_table_entry *next_stream;
+       u64 cur_stream_offset;
+       struct wim_lookup_table_entry *final_stream;
+       size_t list_head_offset;
+};
+
+static struct wim_lookup_table_entry *
+next_stream(struct wim_lookup_table_entry *lte, size_t list_head_offset)
 {
+       struct list_head *cur;
+
+       cur = (struct list_head*)((u8*)lte + list_head_offset);
+
+       return (struct wim_lookup_table_entry*)((u8*)cur->next - list_head_offset);
+}
+
+/* A consume_data_callback_t implementation that translates raw resource data
+ * into streams, calling the begin_stream, consume_chunk, and end_stream
+ * callback functions as appropriate.  */
+static int
+streamifier_cb(const void *chunk, size_t size, void *_ctx)
+{
+       struct streamifier_context *ctx = _ctx;
        int ret;
-       if (size == wim_resource_size(lte)) {
-               /* Do SHA1 */
-               struct extract_ctx ctx;
-               ctx.extract_chunk = extract_chunk;
-               ctx.extract_chunk_arg = extract_chunk_arg;
-               sha1_init(&ctx.sha_ctx);
-               ret = read_resource_prefix(lte, size,
-                                          extract_chunk_sha1_wrapper,
-                                          &ctx, 0);
-               if (ret == 0) {
-                       u8 hash[SHA1_HASH_SIZE];
-                       sha1_final(hash, &ctx.sha_ctx);
-                       if (!hashes_equal(hash, lte->hash)) {
-                       #ifdef ENABLE_ERROR_MESSAGES
-                               ERROR("Invalid SHA1 message digest "
-                                     "on the following WIM resource:");
-                               print_lookup_table_entry(lte, stderr);
-                               if (lte->resource_location == RESOURCE_IN_WIM)
-                                       ERROR("The WIM file appears to be corrupt!");
-                       #endif
-                               ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
-                       }
+
+       DEBUG("%zu bytes passed to streamifier", size);
+
+       wimlib_assert(ctx->cur_stream != NULL);
+       wimlib_assert(size <= ctx->cur_stream->size - ctx->cur_stream_offset);
+
+       if (ctx->cur_stream_offset == 0) {
+               /* Starting a new stream.  */
+               DEBUG("Begin new stream (size=%"PRIu64").",
+                     ctx->cur_stream->size);
+               ret = (*ctx->cbs.begin_stream)(ctx->cur_stream, true,
+                                              ctx->cbs.begin_stream_ctx);
+               if (ret)
+                       return ret;
+       }
+
+       /* Consume the chunk.  */
+       ret = (*ctx->cbs.consume_chunk)(chunk, size,
+                                       ctx->cbs.consume_chunk_ctx);
+       if (ret)
+               return ret;
+       ctx->cur_stream_offset += size;
+
+       if (ctx->cur_stream_offset == ctx->cur_stream->size) {
+               /* Finished reading all the data for a stream.  */
+
+               ctx->cur_stream_offset = 0;
+
+               DEBUG("End stream (size=%"PRIu64").", ctx->cur_stream->size);
+               ret = (*ctx->cbs.end_stream)(ctx->cur_stream, 0,
+                                            ctx->cbs.end_stream_ctx);
+               if (ret)
+                       return ret;
+
+               /* Advance to next stream.  */
+               ctx->cur_stream = ctx->next_stream;
+               if (ctx->cur_stream != NULL) {
+                       if (ctx->cur_stream != ctx->final_stream)
+                               ctx->next_stream = next_stream(ctx->cur_stream,
+                                                              ctx->list_head_offset);
+                       else
+                               ctx->next_stream = NULL;
                }
-       } else {
-               /* Don't do SHA1 */
-               ret = read_resource_prefix(lte, size, extract_chunk,
-                                          extract_chunk_arg, 0);
        }
-       return ret;
+       return 0;
 }
 
+struct hasher_context {
+       SHA_CTX sha_ctx;
+       int flags;
+       struct read_stream_list_callbacks cbs;
+};
+
+/* Callback for starting to read a stream while calculating its SHA1 message
+ * digest.  */
 static int
-extract_wim_chunk_to_fd(const void *buf, size_t len, void *_fd_p)
+hasher_begin_stream(struct wim_lookup_table_entry *lte, bool is_partial_res,
+                   void *_ctx)
 {
-       int fd = *(int*)_fd_p;
-       ssize_t ret = full_write(fd, buf, len);
-       if (ret < len) {
-               ERROR_WITH_ERRNO("Error writing to file descriptor");
-               return WIMLIB_ERR_WRITE;
-       } else {
+       struct hasher_context *ctx = _ctx;
+
+       sha1_init(&ctx->sha_ctx);
+
+       if (ctx->cbs.begin_stream == NULL)
                return 0;
-       }
+       else
+               return (*ctx->cbs.begin_stream)(lte, is_partial_res,
+                                               ctx->cbs.begin_stream_ctx);
 }
 
-int
-extract_wim_resource_to_fd(const struct wim_lookup_table_entry *lte,
-                          int fd, u64 size)
+/* A consume_data_callback_t implementation that continues calculating the SHA1
+ * message digest of the stream being read, then optionally passes the data on
+ * to another consume_data_callback_t implementation.  This allows checking the
+ * SHA1 message digest of a stream being extracted, for example.  */
+static int
+hasher_consume_chunk(const void *chunk, size_t size, void *_ctx)
 {
-       return extract_wim_resource(lte, size, extract_wim_chunk_to_fd, &fd);
-}
+       struct hasher_context *ctx = _ctx;
 
+       sha1_update(&ctx->sha_ctx, chunk, size);
+       if (ctx->cbs.consume_chunk == NULL)
+               return 0;
+       else
+               return (*ctx->cbs.consume_chunk)(chunk, size, ctx->cbs.consume_chunk_ctx);
+}
 
+/* Callback for finishing reading a stream while calculating its SHA1 message
+ * digest.  */
 static int
-sha1_chunk(const void *buf, size_t len, void *ctx)
+hasher_end_stream(struct wim_lookup_table_entry *lte, int status, void *_ctx)
 {
-       sha1_update(ctx, buf, len);
-       return 0;
+       struct hasher_context *ctx = _ctx;
+       u8 hash[SHA1_HASH_SIZE];
+       int ret;
+
+       if (status) {
+               /* Error occurred; the full stream may not have been read.  */
+               ret = status;
+               goto out_next_cb;
+       }
+
+       /* Retrieve the final SHA1 message digest.  */
+       sha1_final(hash, &ctx->sha_ctx);
+
+       if (lte->unhashed) {
+               if (ctx->flags & COMPUTE_MISSING_STREAM_HASHES) {
+                       /* No SHA1 message digest was previously present for the
+                        * stream.  Set it to the one just calculated.  */
+                       DEBUG("Set SHA1 message digest for stream "
+                             "(size=%"PRIu64").", lte->size);
+                       copy_hash(lte->hash, hash);
+               }
+       } else {
+               if (ctx->flags & VERIFY_STREAM_HASHES) {
+                       /* The stream already had a SHA1 message digest present.  Verify
+                        * that it is the same as the calculated value.  */
+                       if (!hashes_equal(hash, lte->hash)) {
+                               if (wimlib_print_errors) {
+                                       ERROR("Invalid SHA1 message digest "
+                                             "on the following WIM stream:");
+                                       print_lookup_table_entry(lte, stderr);
+                               }
+                               ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
+                               errno = EINVAL;
+                               goto out_next_cb;
+                       }
+                       DEBUG("SHA1 message digest okay for "
+                             "stream (size=%"PRIu64").", lte->size);
+               }
+       }
+       ret = 0;
+out_next_cb:
+       if (ctx->cbs.end_stream == NULL)
+               return ret;
+       else
+               return (*ctx->cbs.end_stream)(lte, ret, ctx->cbs.end_stream_ctx);
 }
 
-/* Calculate the SHA1 message digest of a stream. */
-int
-sha1_resource(struct wim_lookup_table_entry *lte)
+static int
+read_full_stream_with_cbs(struct wim_lookup_table_entry *lte,
+                         const struct read_stream_list_callbacks *cbs)
 {
        int ret;
-       SHA_CTX sha_ctx;
 
-       sha1_init(&sha_ctx);
-       ret = read_resource_prefix(lte, wim_resource_size(lte),
-                                  sha1_chunk, &sha_ctx, 0);
-       if (ret == 0)
-               sha1_final(lte->hash, &sha_ctx);
-       return ret;
+       ret = (*cbs->begin_stream)(lte, false, cbs->begin_stream_ctx);
+       if (ret)
+               return ret;
+
+       ret = read_stream_prefix(lte, lte->size, cbs->consume_chunk,
+                                cbs->consume_chunk_ctx);
+
+       return (*cbs->end_stream)(lte, ret, cbs->end_stream_ctx);
+}
+
+/* Read the full data of the specified stream, passing the data into the
+ * specified callbacks (all of which are optional) and either checking or
+ * computing the SHA1 message digest of the stream.  */
+static int
+read_full_stream_with_sha1(struct wim_lookup_table_entry *lte,
+                          const struct read_stream_list_callbacks *cbs)
+{
+       struct hasher_context hasher_ctx = {
+               .flags = VERIFY_STREAM_HASHES | COMPUTE_MISSING_STREAM_HASHES,
+               .cbs = *cbs,
+       };
+       struct read_stream_list_callbacks hasher_cbs = {
+               .begin_stream           = hasher_begin_stream,
+               .begin_stream_ctx       = &hasher_ctx,
+               .consume_chunk          = hasher_consume_chunk,
+               .consume_chunk_ctx      = &hasher_ctx,
+               .end_stream             = hasher_end_stream,
+               .end_stream_ctx         = &hasher_ctx,
+
+       };
+       return read_full_stream_with_cbs(lte, &hasher_cbs);
 }
 
 /*
- * 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.
+ * Read a list of streams, each of which may be in any supported location (e.g.
+ * in a WIM or in an external file).  Unlike read_stream_prefix() or the
+ * functions which call it, this function optimizes the case where multiple
+ * streams are packed into a single compressed WIM resource and reads them all
+ * consecutively, only decompressing the data one time.
  *
- * The output_resource_entry, out_refcnt, and part_number fields of @lte are
- * updated.
+ * @stream_list
+ *     List of streams (represented as `struct wim_lookup_table_entry's) to
+ *     read.
+ * @list_head_offset
+ *     Offset of the `struct list_head' within each `struct
+ *     wim_lookup_table_entry' that makes up the @stream_list.
+ * @cbs
+ *     Callback functions to accept the stream data.
+ * @flags
+ *     Bitwise OR of zero or more of the following flags:
  *
- * (This function is confusing and should be refactored somehow.)
+ *     VERIFY_STREAM_HASHES:
+ *             For all streams being read that have already had SHA1 message
+ *             digests computed, calculate the SHA1 message digest of the read
+ *             data and compare it with the previously computed value.  If they
+ *             do not match, return WIMLIB_ERR_INVALID_RESOURCE_HASH.
+ *
+ *     COMPUTE_MISSING_STREAM_HASHES
+ *             For all streams being read that have not yet had their SHA1
+ *             message digests computed, calculate and save their SHA1 message
+ *             digests.
+ *
+ *     STREAM_LIST_ALREADY_SORTED
+ *             @stream_list is already sorted in sequential order for reading.
+ *
+ * The callback functions are allowed to delete the current stream from the list
+ * if necessary.
+ *
+ * Returns 0 on success; a nonzero error code on failure.  Failure can occur due
+ * to an error reading the data or due to an error status being returned by any
+ * of the callback functions.
  */
 int
-copy_resource(struct wim_lookup_table_entry *lte, void *wim)
+read_stream_list(struct list_head *stream_list,
+                size_t list_head_offset,
+                const struct read_stream_list_callbacks *cbs,
+                int flags)
 {
-       WIMStruct *w = wim;
        int ret;
+       struct list_head *cur, *next;
+       struct wim_lookup_table_entry *lte;
+       struct hasher_context *hasher_ctx;
+       struct read_stream_list_callbacks *sink_cbs;
+
+       if (!(flags & STREAM_LIST_ALREADY_SORTED)) {
+               ret = sort_stream_list_by_sequential_order(stream_list, list_head_offset);
+               if (ret)
+                       return ret;
+       }
 
-       ret = write_wim_resource(lte, w->out_fd,
-                                wim_resource_compression_type(lte),
-                                &lte->output_resource_entry, 0);
-       if (ret == 0) {
-               lte->out_refcnt = lte->refcnt;
-               lte->part_number = w->hdr.part_number;
+       if (flags & (VERIFY_STREAM_HASHES | COMPUTE_MISSING_STREAM_HASHES)) {
+               hasher_ctx = alloca(sizeof(*hasher_ctx));
+               *hasher_ctx = (struct hasher_context) {
+                       .flags  = flags,
+                       .cbs    = *cbs,
+               };
+               sink_cbs = alloca(sizeof(*sink_cbs));
+               *sink_cbs = (struct read_stream_list_callbacks) {
+                       .begin_stream           = hasher_begin_stream,
+                       .begin_stream_ctx       = hasher_ctx,
+                       .consume_chunk          = hasher_consume_chunk,
+                       .consume_chunk_ctx      = hasher_ctx,
+                       .end_stream             = hasher_end_stream,
+                       .end_stream_ctx         = hasher_ctx,
+               };
+       } else {
+               sink_cbs = (struct read_stream_list_callbacks*)cbs;
        }
-       return ret;
+
+       for (cur = stream_list->next, next = cur->next;
+            cur != stream_list;
+            cur = next, next = cur->next)
+       {
+               lte = (struct wim_lookup_table_entry*)((u8*)cur - list_head_offset);
+
+               if (lte->flags & WIM_RESHDR_FLAG_PACKED_STREAMS &&
+                   lte->size != lte->rspec->uncompressed_size)
+               {
+
+                       struct wim_lookup_table_entry *lte_next, *lte_last;
+                       struct list_head *next2;
+                       size_t stream_count;
+
+                       /* The next stream is a proper sub-sequence of a WIM
+                        * resource.  See if there are other streams in the same
+                        * resource that need to be read.  Since
+                        * sort_stream_list_by_sequential_order() sorted the
+                        * streams by offset in the WIM, this can be determined
+                        * by simply scanning forward in the list.  */
+
+                       lte_last = lte;
+                       stream_count = 1;
+                       for (next2 = next;
+                            next2 != stream_list
+                            && (lte_next = (struct wim_lookup_table_entry*)
+                                               ((u8*)next2 - list_head_offset),
+                                lte_next->resource_location == RESOURCE_IN_WIM
+                                && lte_next->rspec == lte->rspec);
+                            next2 = next2->next)
+                       {
+                               lte_last = lte_next;
+                               stream_count++;
+                       }
+                       if (stream_count > 1) {
+                               /* Reading multiple streams combined into a
+                                * single WIM resource.  They are in the stream
+                                * list, sorted by offset; @lte specifies the
+                                * first stream in the resource that needs to be
+                                * read and @lte_last specifies the last stream
+                                * in the resource that needs to be read.  */
+
+                               DEBUG("Reading %zu streams combined in same "
+                                     "WIM resource", stream_count);
+
+                               next = next2;
+
+                               struct data_range ranges[stream_count];
+
+                               {
+                                       struct list_head *next3;
+                                       size_t i;
+                                       struct wim_lookup_table_entry *lte_cur;
+
+                                       next3 = cur;
+                                       for (i = 0; i < stream_count; i++) {
+                                               lte_cur = (struct wim_lookup_table_entry*)
+                                                       ((u8*)next3 - list_head_offset);
+                                               ranges[i].offset = lte_cur->offset_in_res;
+                                               ranges[i].size = lte_cur->size;
+                                               next3 = next3->next;
+                                       }
+                               }
+
+                               struct streamifier_context streamifier_ctx = {
+                                       .cbs                    = *sink_cbs,
+                                       .cur_stream             = lte,
+                                       .next_stream            = next_stream(lte, list_head_offset),
+                                       .cur_stream_offset      = 0,
+                                       .final_stream           = lte_last,
+                                       .list_head_offset       = list_head_offset,
+                               };
+
+                               ret = read_compressed_wim_resource(lte->rspec,
+                                                                  ranges,
+                                                                  stream_count,
+                                                                  streamifier_cb,
+                                                                  &streamifier_ctx);
+
+                               if (ret) {
+                                       if (streamifier_ctx.cur_stream_offset != 0) {
+                                               ret = (*streamifier_ctx.cbs.end_stream)
+                                                       (streamifier_ctx.cur_stream,
+                                                        ret,
+                                                        streamifier_ctx.cbs.end_stream_ctx);
+                                       }
+                                       return ret;
+                               }
+                               continue;
+                       }
+               }
+
+               ret = read_full_stream_with_cbs(lte, sink_cbs);
+               if (ret && ret != BEGIN_STREAM_STATUS_SKIP_STREAM)
+                       return ret;
+       }
+       return 0;
+}
+
+/* Extract the first @size bytes of the specified stream.
+ *
+ * If @size specifies the full uncompressed size of the stream, then the SHA1
+ * message digest of the uncompressed stream is checked while being extracted.
+ *
+ * The uncompressed data of the resource is passed in chunks of unspecified size
+ * to the @extract_chunk function, passing it @extract_chunk_arg.  */
+int
+extract_stream(struct wim_lookup_table_entry *lte, u64 size,
+              consume_data_callback_t extract_chunk, void *extract_chunk_arg)
+{
+       wimlib_assert(size <= lte->size);
+       if (size == lte->size) {
+               /* Do SHA1.  */
+               struct read_stream_list_callbacks cbs = {
+                       .consume_chunk          = extract_chunk,
+                       .consume_chunk_ctx      = extract_chunk_arg,
+               };
+               return read_full_stream_with_sha1(lte, &cbs);
+       } else {
+               /* Don't do SHA1.  */
+               return read_stream_prefix(lte, size, extract_chunk,
+                                         extract_chunk_arg);
+       }
+}
+
+/* A consume_data_callback_t implementation that writes the chunk of data to a
+ * file descriptor.  */
+int
+extract_chunk_to_fd(const void *chunk, size_t size, void *_fd_p)
+{
+       struct filedes *fd = _fd_p;
+
+       int ret = full_write(fd, chunk, size);
+       if (ret) {
+               ERROR_WITH_ERRNO("Error writing to file descriptor");
+               return ret;
+       }
+       return 0;
+}
+
+/* Extract the first @size bytes of the specified stream to the specified file
+ * descriptor.  */
+int
+extract_stream_to_fd(struct wim_lookup_table_entry *lte,
+                    struct filedes *fd, u64 size)
+{
+       return extract_stream(lte, size, extract_chunk_to_fd, fd);
+}
+
+/* Calculate the SHA1 message digest of a stream and store it in @lte->hash.  */
+int
+sha1_stream(struct wim_lookup_table_entry *lte)
+{
+       wimlib_assert(lte->unhashed);
+       struct read_stream_list_callbacks cbs = {
+       };
+       return read_full_stream_with_sha1(lte, &cbs);
+}
+
+/* Convert a short WIM resource header to a stand-alone WIM resource
+ * specification.  */
+void
+wim_res_hdr_to_spec(const struct wim_reshdr *reshdr, WIMStruct *wim,
+                   struct wim_resource_spec *rspec)
+{
+       rspec->wim = wim;
+       rspec->offset_in_wim = reshdr->offset_in_wim;
+       rspec->size_in_wim = reshdr->size_in_wim;
+       rspec->uncompressed_size = reshdr->uncompressed_size;
+       INIT_LIST_HEAD(&rspec->stream_list);
+       rspec->flags = reshdr->flags;
+       rspec->is_pipable = wim_is_pipable(wim);
+}
+
+/* Convert a stand-alone resource specification to a WIM resource header.  */
+void
+wim_res_spec_to_hdr(const struct wim_resource_spec *rspec,
+                   struct wim_reshdr *reshdr)
+{
+       reshdr->offset_in_wim     = rspec->offset_in_wim;
+       reshdr->size_in_wim       = rspec->size_in_wim;
+       reshdr->flags             = rspec->flags;
+       reshdr->uncompressed_size = rspec->uncompressed_size;
+}
+
+/* Translates a WIM resource header from the on-disk format into an in-memory
+ * format.  */
+void
+get_wim_reshdr(const struct wim_reshdr_disk *disk_reshdr,
+              struct wim_reshdr *reshdr)
+{
+       reshdr->offset_in_wim = le64_to_cpu(disk_reshdr->offset_in_wim);
+       reshdr->size_in_wim = (((u64)disk_reshdr->size_in_wim[0] <<  0) |
+                              ((u64)disk_reshdr->size_in_wim[1] <<  8) |
+                              ((u64)disk_reshdr->size_in_wim[2] << 16) |
+                              ((u64)disk_reshdr->size_in_wim[3] << 24) |
+                              ((u64)disk_reshdr->size_in_wim[4] << 32) |
+                              ((u64)disk_reshdr->size_in_wim[5] << 40) |
+                              ((u64)disk_reshdr->size_in_wim[6] << 48));
+       reshdr->uncompressed_size = le64_to_cpu(disk_reshdr->uncompressed_size);
+       reshdr->flags = disk_reshdr->flags;
+}
+
+/* Translates a WIM resource header from an in-memory format into the on-disk
+ * format.  */
+void
+put_wim_reshdr(const struct wim_reshdr *reshdr,
+              struct wim_reshdr_disk *disk_reshdr)
+{
+       disk_reshdr->size_in_wim[0] = reshdr->size_in_wim  >>  0;
+       disk_reshdr->size_in_wim[1] = reshdr->size_in_wim  >>  8;
+       disk_reshdr->size_in_wim[2] = reshdr->size_in_wim  >> 16;
+       disk_reshdr->size_in_wim[3] = reshdr->size_in_wim  >> 24;
+       disk_reshdr->size_in_wim[4] = reshdr->size_in_wim  >> 32;
+       disk_reshdr->size_in_wim[5] = reshdr->size_in_wim  >> 40;
+       disk_reshdr->size_in_wim[6] = reshdr->size_in_wim  >> 48;
+       disk_reshdr->flags = reshdr->flags;
+       disk_reshdr->offset_in_wim = cpu_to_le64(reshdr->offset_in_wim);
+       disk_reshdr->uncompressed_size = cpu_to_le64(reshdr->uncompressed_size);
 }