X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=src%2Fresource.c;h=385f9f65ba6836aa594c5bb34e9b4823eabff79c;hp=03d6e0c47d35aeaef0d3160b3be5115c8ec5c965;hb=8618172276fae088f311923a61bbf26c3d4d8941;hpb=61db93f82eca3fe9f7676355c709c58cc425a6ad

diff --git a/src/resource.c b/src/resource.c
index 03d6e0c4..385f9f65 100644
--- a/src/resource.c
+++ b/src/resource.c
@@ -1,893 +1,803 @@
 /*
  * resource.c
  *
- * Read uncompressed and compressed metadata and file resources from a WIM file.
+ * Code for reading blobs and resources, including compressed WIM resources.
  */
 
 /*
- * Copyright (C) 2012, 2013 Eric Biggers
+ * Copyright (C) 2012, 2013, 2015 Eric Biggers
  *
- * This file is part of wimlib, a library for working with WIM files.
+ * This file is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation; either version 3 of the License, or (at your option) any
+ * later version.
  *
- * wimlib is free software; you can redistribute it and/or modify it under the
- * terms of the GNU General Public License as published by the Free Software
- * Foundation; either version 3 of the License, or (at your option) any later
- * version.
+ * This file is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
+ * details.
  *
- * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
- * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along with
- * wimlib; if not, see http://www.gnu.org/licenses/.
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this file; if not, see http://www.gnu.org/licenses/.
  */
 
 #ifdef HAVE_CONFIG_H
 #  include "config.h"
 #endif
 
-#include "wimlib.h"
-#include "wimlib/dentry.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "wimlib/alloca.h"
+#include "wimlib/assert.h"
+#include "wimlib/bitops.h"
+#include "wimlib/blob_table.h"
 #include "wimlib/endianness.h"
 #include "wimlib/error.h"
 #include "wimlib/file_io.h"
-#include "wimlib/lookup_table.h"
+#include "wimlib/ntfs_3g.h"
 #include "wimlib/resource.h"
 #include "wimlib/sha1.h"
-
-#ifdef __WIN32__
-/* for read_win32_file_prefix(), read_win32_encrypted_file_prefix() */
-#  include "wimlib/win32.h"
-#endif
-
-#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 <stdarg.h>
-#include <stdlib.h>
-#include <unistd.h>
+#include "wimlib/wim.h"
+#include "wimlib/win32.h"
 
 /*
- *                            Compressed resources
- *
- * A compressed resource in a WIM consists of a number of consecutive LZX or
- * XPRESS-compressed chunks, each of which decompresses to 32768 bytes of data,
- * 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.
+ *                         Compressed WIM resources
  *
- * Additional information:
+ * A compressed resource in a WIM consists of a sequence of chunks.  Each chunk
+ * decompresses to the same size except possibly for the last, which
+ * decompresses to the remaining size.  Chunks that did not compress to less
+ * than their original size are stored uncompressed.
  *
- * - 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.
+ * We support three variations on this resource format, independently of the
+ * compression type and chunk size which can vary as well:
  *
- * - The chunk table is included in the compressed size of the resource provided
- *   in the corresponding entry in the WIM's stream lookup table.
+ * - Original resource format: immediately before the compressed chunks, 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.  Chunk table
+ *   entries are 32-bit for resources < 4 GiB uncompressed and 64-bit for
+ *   resources >= 4 GiB uncompressed.
  *
- * - 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.
+ * - Solid resource format (distinguished by the use of WIM_RESHDR_FLAG_SOLID
+ *   instead of WIM_RESHDR_FLAG_COMPRESSED): similar to the original format, but
+ *   the resource begins with a 16-byte header which specifies the uncompressed
+ *   size of the resource, the compression type, and the chunk size.  (In the
+ *   original format, these values were instead determined from outside the
+ *   resource itself, from the blob table and the WIM file header.) In addition,
+ *   in this format the entries in the chunk table contain compressed chunk
+ *   sizes rather than offsets.  As a consequence of this, the chunk table
+ *   entries are always 32-bit and there is an entry for chunk 0.
  *
- * 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 (less than or
- * equal to 32768).  Otherwise the details are the same.
+ * - Pipable resource format (wimlib extension; all resources in a pipable WIM
+ *   have this format): similar to the original format, but the chunk table is
+ *   at the end of the resource rather than the beginning, and each compressed
+ *   chunk is prefixed with its compressed size as a 32-bit integer.  This
+ *   format allows a resource to be written without rewinding.
  */
 
-typedef int (*decompress_func_t)(const void *, unsigned, void *, unsigned);
 
-static decompress_func_t
-get_decompress_func(int ctype)
-{
-	if (ctype == WIMLIB_COMPRESSION_TYPE_LZX)
-		return wimlib_lzx_decompress;
-	else
-		return wimlib_xpress_decompress;
-}
+struct data_range {
+	u64 offset;
+	u64 size;
+};
 
 /*
- * read_compressed_resource()-
+ * Read data from a compressed WIM resource.
  *
- * Read data from a compressed resource being read from a seekable WIM file.
- * The resource may be either pipable or non-pipable.
+ * @rdesc
+ *	Description 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.
+ * @cbs
+ *	Structure which provides the consume_chunk() callback to feed the data
+ *	being read.  Each call provides the next chunk of the requested data,
+ *	uncompressed.  Each chunk will be nonempty and will not cross range
+ *	boundaries but otherwise will be of unspecified size.
  *
- * @flags may be:
+ * Possible return values:
  *
- * 0:
- *	Just do a normal read, decompressing the data if necessary.
+ *	WIMLIB_ERR_SUCCESS (0)
+ *	WIMLIB_ERR_READ			  (errno set)
+ *	WIMLIB_ERR_UNEXPECTED_END_OF_FILE (errno set to EINVAL)
+ *	WIMLIB_ERR_NOMEM		  (errno set to ENOMEM)
+ *	WIMLIB_ERR_DECOMPRESSION	  (errno set to EINVAL)
+ *	WIMLIB_ERR_INVALID_CHUNK_SIZE	  (errno set to EINVAL)
  *
- * WIMLIB_READ_RESOURCE_FLAG_RAW_CHUNKS:
- *	Read the raw contents of the compressed chunks of the compressed
- *	resource.  For pipable resources, this does *not* include the chunk
- *	headers.  If a callback function is being used, it will be called once
- *	for each compressed chunk.  For non-pipable resources, this mode
- *	excludes the chunk table.  For pipable resources, this mode excludes the
- *	stream and chunk headers.
+ *	or other error code returned by the cbs->consume_chunk() function.
  */
 static int
-read_compressed_resource(const struct wim_lookup_table_entry *lte,
-			 u64 size, consume_data_callback_t cb,
-			 void *ctx_or_buf, int flags, u64 offset)
+read_compressed_wim_resource(const struct wim_resource_descriptor * const rdesc,
+			     const struct data_range * const ranges,
+			     const size_t num_ranges,
+			     const struct read_blob_callbacks *cbs)
 {
 	int ret;
+	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(num_ranges != 0);
+	for (size_t i = 0; i < num_ranges; i++) {
+		wimlib_assert(ranges[i].offset + ranges[i].size > ranges[i].offset &&
+			      ranges[i].offset + ranges[i].size <= rdesc->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 = &rdesc->wim->in_fd;
+
+	/* Determine if we're reading a pipable resource from a pipe or not.  */
+	const bool is_pipe_read = (rdesc->is_pipable && !filedes_is_seekable(in_fd));
+
+	/* Determine if the chunk table is in an alternate format.  */
+	const bool alt_chunk_table = (rdesc->flags & WIM_RESHDR_FLAG_SOLID)
+					&& !is_pipe_read;
+
+	/* Get the maximum size of uncompressed chunks in this resource, which
+	 * we require be a power of 2.  */
+	u64 cur_read_offset = rdesc->offset_in_wim;
+	int ctype = rdesc->compression_type;
+	u32 chunk_size = rdesc->chunk_size;
+	if (alt_chunk_table) {
+		/* Alternate chunk table format.  Its header specifies the chunk
+		 * size and compression format.  Note: it could be read here;
+		 * however, the relevant data was already loaded into @rdesc by
+		 * read_blob_table().  */
+		cur_read_offset += sizeof(struct alt_chunk_table_header_disk);
+	}
 
-	/* Currently, reading raw compressed chunks is only guaranteed to work
-	 * correctly when the full resource is requested.  Furthermore, in such
-	 * cases the requested size is specified as the compressed size, but
-	 * here we change it to an uncompressed size to avoid confusing the rest
-	 * of this function.  */
-	if (flags & WIMLIB_READ_RESOURCE_FLAG_RAW_CHUNKS) {
-		wimlib_assert(offset == 0);
-		wimlib_assert(size == lte->resource_entry.size);
-		size = wim_resource_size(lte);
+	if (unlikely(!is_power_of_2(chunk_size))) {
+		ERROR("Invalid compressed resource: "
+		      "expected power-of-2 chunk size (got %"PRIu32")",
+		      chunk_size);
+		ret = WIMLIB_ERR_INVALID_CHUNK_SIZE;
+		errno = EINVAL;
+		goto out_cleanup;
 	}
 
-	wimlib_assert(offset + size <= wim_resource_size(lte));
+	/* Get valid decompressor.  */
+	if (likely(ctype == rdesc->wim->decompressor_ctype &&
+		   chunk_size == rdesc->wim->decompressor_max_block_size))
+	{
+		/* Cached decompressor.  */
+		decompressor = rdesc->wim->decompressor;
+		rdesc->wim->decompressor_ctype = WIMLIB_COMPRESSION_TYPE_NONE;
+		rdesc->wim->decompressor = NULL;
+	} else {
+		ret = wimlib_create_decompressor(ctype, chunk_size,
+						 &decompressor);
+		if (unlikely(ret)) {
+			if (ret != WIMLIB_ERR_NOMEM)
+				errno = EINVAL;
+			goto out_cleanup;
+		}
+	}
 
-	/* Handle the trivial case.  */
-	if (size == 0)
-		return 0;
+	const u32 chunk_order = bsr32(chunk_size);
 
-	/* Get the appropriate decompression function.  */
-	decompress_func_t decompress =
-			get_decompress_func(wim_resource_compression_type(lte));
+	/* Calculate the total number of chunks the resource is divided into.  */
+	const u64 num_chunks = (rdesc->uncompressed_size + chunk_size - 1) >> chunk_order;
 
-	/* Get the file descriptor for the WIM.  */
-	struct filedes *in_fd = &lte->wim->in_fd;
+	/* 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 number of chunks the resource is divided into.  */
-	u64 num_chunks = wim_resource_chunks(lte);
+	/* 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 entries in the chunk table; it's one less
-	 * than the number of chunks, since the first chunk has no entry.  */
-	u64 num_chunk_entries = num_chunks - 1;
+	/* 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 0-based index of the chunk at which the read starts.
-	 */
-	u64 start_chunk = offset / WIM_CHUNK_SIZE;
-
-	/* Calculate the offset, within the start chunk, of the first byte of
-	 * the read.  */
-	u64 start_offset_in_chunk = offset % WIM_CHUNK_SIZE;
-
-	/* Calculate the index of the chunk that contains the last byte of the
-	 * read.  */
-	u64 end_chunk = (offset + size - 1) / WIM_CHUNK_SIZE;
-
-	/* Calculate the offset, within the end chunk, of the last byte of the
-	 * read.  */
-	u64 end_offset_in_chunk = (offset + size - 1) % WIM_CHUNK_SIZE;
-
-	/* Calculate the number of chunk entries are actually needed to read the
-	 * requested part of the resource.  Include an entry for the first chunk
-	 * even though that doesn't exist in the on-disk table, but take into
-	 * account that if the last chunk required for the read is not the last
-	 * chunk of the resource, an extra chunk entry is needed so that the
-	 * compressed size of the last chunk of the read can be determined.  */
-	u64 num_alloc_chunk_entries = end_chunk - start_chunk + 1;
-	if (end_chunk != num_chunks - 1)
-		num_alloc_chunk_entries++;
+	/* 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.  */
-	u64 chunk_entry_size = (wim_resource_size(lte) > ((u64)1 << 32)) ? 8 : 4;
-
-	/* Calculate the size, in bytes, of the full chunk table.  */
-	u64 chunk_table_size = num_chunk_entries * chunk_entry_size;
-
-	/* Allocate a buffer to hold a subset of the chunk table.  It will only
-	 * contain offsets for the chunks that are actually needed for this
-	 * read.  For speed, allocate the buffer on the stack unless it's too
-	 * large.  */
-	u64 *chunk_offsets;
-	bool chunk_offsets_malloced;
-	if (num_alloc_chunk_entries < 1024) {
-		chunk_offsets = alloca(num_alloc_chunk_entries * sizeof(u64));
-		chunk_offsets_malloced = false;
-	} else {
-		chunk_offsets = malloc(num_alloc_chunk_entries * sizeof(u64));
-		if (!chunk_offsets) {
-			ERROR("Failed to allocate chunk table "
-			      "with %"PRIu64" entries", num_alloc_chunk_entries);
-			return WIMLIB_ERR_NOMEM;
+	const u64 chunk_entry_size = get_chunk_entry_size(rdesc->uncompressed_size,
+							  alt_chunk_table);
+
+	/* 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 num_chunk_entries_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;
+			num_chunk_entries_to_read = last_needed_chunk + 1;
+		} else {
+
+			num_chunk_entries_to_read = last_needed_chunk - read_start_chunk + 1;
+
+			/* The first chunk has no explicit chunk table entry.  */
+			if (read_start_chunk == 0) {
+				num_chunk_entries_to_read--;
+				first_chunk_entry_to_read = 0;
+			} else {
+				first_chunk_entry_to_read = read_start_chunk - 1;
+			}
+
+			/* Unless we're reading the final chunk of the resource,
+			 * we need the offset of the chunk following the last
+			 * needed chunk so that the compressed size of the last
+			 * needed chunk can be computed.  */
+			if (last_needed_chunk < num_chunks - 1)
+				num_chunk_entries_to_read++;
 		}
-		chunk_offsets_malloced = true;
-	}
 
-	/* Set the implicit offset of the first chunk if it's included in the
-	 * needed chunks.  */
-	if (start_chunk == 0)
-		chunk_offsets[0] = 0;
-
-	/* Calculate the index of the first needed entry in the chunk table.  */
-	u64 start_table_idx = (start_chunk == 0) ? 0 : start_chunk - 1;
-
-	/* Calculate the number of entries that need to be read from the chunk
-	 * table.  */
-	u64 num_needed_chunk_entries = (start_chunk == 0) ?
-				num_alloc_chunk_entries - 1 : num_alloc_chunk_entries;
-
-	/* Calculate the number of bytes of data that need to be read from the
-	 * chunk table.  */
-	size_t chunk_table_needed_size =
-				num_needed_chunk_entries * chunk_entry_size;
-	if ((u64)chunk_table_needed_size !=
-	    num_needed_chunk_entries * chunk_entry_size)
-	{
-		ERROR("Compressed read request too large to fit into memory!");
-		ret = WIMLIB_ERR_NOMEM;
-		goto out_free_chunk_offsets;
-	}
+		const u64 chunk_offsets_alloc_size =
+			max(num_chunk_entries_to_read,
+			    num_needed_chunk_offsets) * sizeof(chunk_offsets[0]);
 
-	/* Calculate the byte offset, in the WIM file, of the first chunk table
-	 * entry to read.  Take into account that if the WIM file is in the
-	 * special "pipable" format, then the chunk table is at the end of the
-	 * resource, not the beginning.  */
-	u64 file_offset_of_needed_chunk_entries =
-			lte->resource_entry.offset + (start_table_idx *
-						      chunk_entry_size);
-	if (lte->is_pipable)
-		file_offset_of_needed_chunk_entries += lte->resource_entry.size -
-						       chunk_table_size;
-
-	/* Read the needed chunk table entries into the end of the chunk_offsets
-	 * buffer.  */
-	void *chunk_tab_data = (u8*)&chunk_offsets[num_alloc_chunk_entries] -
-				chunk_table_needed_size;
-	ret = full_pread(in_fd, chunk_tab_data, chunk_table_needed_size,
-			 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.  Careful: chunk_offsets aliases chunk_tab_data, which
-	 * breaks C's aliasing rules when we read 32-bit integers and store
-	 * 64-bit integers.  But since the operations are safe as long as the
-	 * compiler doesn't mess with their order, we use the gcc may_alias
-	 * extension to tell the compiler that loads from the 32-bit integers
-	 * may alias stores to the 64-bit integers.  */
-	{
-		typedef le64 __attribute__((may_alias)) aliased_le64_t;
-		typedef le32 __attribute__((may_alias)) aliased_le32_t;
-		u64 *chunk_offsets_p = chunk_offsets;
-		u64 i;
-
-		if (start_chunk == 0)
-			chunk_offsets_p++;
-
-		if (chunk_entry_size == 4) {
-			aliased_le32_t *raw_entries = (aliased_le32_t*)chunk_tab_data;
-			for (i = 0; i < num_needed_chunk_entries; i++)
-				chunk_offsets_p[i] = le32_to_cpu(raw_entries[i]);
+		if (unlikely((size_t)chunk_offsets_alloc_size != chunk_offsets_alloc_size)) {
+			errno = ENOMEM;
+			goto oom;
+		}
+
+		if (likely(chunk_offsets_alloc_size <= STACK_MAX)) {
+			chunk_offsets = alloca(chunk_offsets_alloc_size);
 		} else {
-			aliased_le64_t *raw_entries = (aliased_le64_t*)chunk_tab_data;
-			for (i = 0; i < num_needed_chunk_entries; i++)
-				chunk_offsets_p[i] = le64_to_cpu(raw_entries[i]);
+			chunk_offsets = MALLOC(chunk_offsets_alloc_size);
+			if (unlikely(!chunk_offsets))
+				goto oom;
+			chunk_offsets_malloced = true;
 		}
-	}
 
-	/* Calculate file offset of the first chunk that needs to be read.  N.B.
-	 * if the resource is pipable, the entries in the chunk table do *not*
-	 * include the chunk headers.  */
-	u64 cur_read_offset = lte->resource_entry.offset + chunk_offsets[0];
-	if (!lte->is_pipable)
-		cur_read_offset += chunk_table_size;
-	else
-		cur_read_offset += start_chunk *
-				   sizeof(struct pwm_chunk_hdr);
-
-	/* If using a callback function, allocate a temporary buffer that will
-	 * be used to pass data to it.  If writing directly to a buffer instead,
-	 * arrange to write data directly into it.  */
-	u8 *out_p;
-	if (cb)
-		out_p = alloca(WIM_CHUNK_SIZE);
-	else
-		out_p = ctx_or_buf;
-
-	/* Unless the raw compressed data was requested, allocate a temporary
-	 * buffer for reading compressed chunks, each of which can be at most
-	 * WIM_CHUNK_SIZE - 1 bytes.  This excludes compressed chunks that are a
-	 * full WIM_CHUNK_SIZE bytes, which are handled separately.  */
-	void *compressed_buf;
-	if (!(flags & WIMLIB_READ_RESOURCE_FLAG_RAW_CHUNKS))
-		compressed_buf = alloca(WIM_CHUNK_SIZE - 1);
-
-	/* Read, and possibly decompress, each needed chunk, either writing the
-	 * data directly into the @ctx_or_buf buffer or passing it to the @cb
-	 * callback function.  */
-	for (u64 i = start_chunk; i <= end_chunk; i++) {
-
-		/* If the resource is pipable, skip the chunk header.  */
-		if (lte->is_pipable)
-			cur_read_offset += sizeof(struct pwm_chunk_hdr);
+		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)
+			+ (rdesc->is_pipable ? (rdesc->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 (unlikely(ret))
+			goto read_error;
 
-		/* 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) {
-			/* Not the last chunk.  Compressed size is given by
-			 * difference of chunk table entries; uncompressed size
-			 * is always 32768 bytes.  */
-			compressed_chunk_size = chunk_offsets[i + 1 - start_chunk] -
-						chunk_offsets[i - start_chunk];
-			uncompressed_chunk_size = WIM_CHUNK_SIZE;
+		/* 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 _may_alias_attribute aliased_le64_t;
+		typedef le32 _may_alias_attribute 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 {
-			/* Last chunk.  Compressed size is the remaining size in
-			 * the compressed resource; uncompressed size is the
-			 * remaining size in the uncompressed resource.  */
-			compressed_chunk_size = lte->resource_entry.size -
-						chunk_table_size -
-						chunk_offsets[i - start_chunk];
-			if (lte->is_pipable)
-				compressed_chunk_size -= num_chunks *
-							 sizeof(struct pwm_chunk_hdr);
-
-			if (wim_resource_size(lte) % WIM_CHUNK_SIZE == 0)
-				uncompressed_chunk_size = WIM_CHUNK_SIZE;
-			else
-				uncompressed_chunk_size = wim_resource_size(lte) %
-							  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]);
+			}
 		}
 
-		/* Calculate how much of this chunk needs to be read.  */
+		/* Set offset to beginning of first chunk to read.  */
+		cur_read_offset += chunk_offsets[0];
+		if (rdesc->is_pipable)
+			cur_read_offset += read_start_chunk * sizeof(struct pwm_chunk_hdr);
+		else
+			cur_read_offset += chunk_table_size;
+	}
 
-		unsigned partial_chunk_size;
-		u64 start_offset = 0;
-		u64 end_offset = WIM_CHUNK_SIZE - 1;
+	/* 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 (unlikely(!ubuf))
+			goto oom;
+		ubuf_malloced = true;
+	}
 
-		if (flags & WIMLIB_READ_RESOURCE_FLAG_RAW_CHUNKS) {
-			partial_chunk_size = compressed_chunk_size;
-		} else {
-			if (i == start_chunk)
-				start_offset = start_offset_in_chunk;
+	/* 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 (unlikely(!cbuf))
+			goto oom;
+		cbuf_malloced = true;
+	}
 
-			if (i == end_chunk)
-				end_offset = end_offset_in_chunk;
+	/* 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;
 
-			partial_chunk_size = end_offset + 1 - start_offset;
-		}
+	/* Read and process each needed chunk.  */
+	for (u64 i = read_start_chunk; i <= last_needed_chunk; i++) {
 
-		if (compressed_chunk_size == uncompressed_chunk_size ||
-		    (flags & WIMLIB_READ_RESOURCE_FLAG_RAW_CHUNKS))
-		{
-			/* Chunk stored uncompressed, or reading raw chunk data.  */
-			ret = full_pread(in_fd,
-					 cb ? out_p + start_offset : out_p,
-					 partial_chunk_size,
-					 cur_read_offset + start_offset);
-			if (ret)
+		/* Calculate uncompressed size of next chunk.  */
+		u32 chunk_usize;
+		if ((i == num_chunks - 1) && (rdesc->uncompressed_size & (chunk_size - 1)))
+			chunk_usize = (rdesc->uncompressed_size & (chunk_size - 1));
+		else
+			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 (unlikely(ret))
 				goto read_error;
+			chunk_csize = le32_to_cpu(chunk_hdr.compressed_size);
+		} else {
+			if (i == num_chunks - 1) {
+				chunk_csize = rdesc->size_in_wim -
+					      chunk_table_full_size -
+					      chunk_offsets[i - read_start_chunk];
+				if (rdesc->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 (unlikely(chunk_csize == 0 || chunk_csize > chunk_usize)) {
+			ERROR("Invalid chunk size in compressed resource!");
+			errno = EINVAL;
+			ret = WIMLIB_ERR_DECOMPRESSION;
+			goto out_cleanup;
+		}
+		if (rdesc->is_pipable)
+			cur_read_offset += sizeof(struct pwm_chunk_hdr);
+
+		/* 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 (unlikely(ret))
+					goto read_error;
+			}
 		} else {
-			/* Compressed chunk and not doing raw read.  */
 
-			/* Read the compressed data into compressed_buf.  */
+			/* Read the chunk and feed data to the callback
+			 * function.  */
+			u8 *read_buf;
+
+			if (chunk_csize == chunk_usize)
+				read_buf = ubuf;
+			else
+				read_buf = cbuf;
+
 			ret = full_pread(in_fd,
-					 compressed_buf,
-					 compressed_chunk_size,
+					 read_buf,
+					 chunk_csize,
 					 cur_read_offset);
-			if (ret)
+			if (unlikely(ret))
 				goto read_error;
 
-			/* 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 (partial_chunk_size != uncompressed_chunk_size &&
-			    cb == NULL)
-			{
-				u8 uncompressed_buf[uncompressed_chunk_size];
-
-				ret = (*decompress)(compressed_buf,
-						    compressed_chunk_size,
-						    uncompressed_buf,
-						    uncompressed_chunk_size);
-				if (ret) {
+			if (read_buf == cbuf) {
+				ret = wimlib_decompress(cbuf,
+							chunk_csize,
+							ubuf,
+							chunk_usize,
+							decompressor);
+				if (unlikely(ret)) {
+					ERROR("Failed to decompress data!");
 					ret = WIMLIB_ERR_DECOMPRESSION;
 					errno = EINVAL;
-					goto out_free_chunk_offsets;
-				}
-				memcpy(out_p, uncompressed_buf + start_offset,
-				       partial_chunk_size);
-			} else {
-				ret = (*decompress)(compressed_buf,
-						    compressed_chunk_size,
-						    out_p,
-						    uncompressed_chunk_size);
-				if (ret) {
-					ret = WIMLIB_ERR_DECOMPRESSION;
-					errno = EINVAL;
-					goto out_free_chunk_offsets;
+					goto out_cleanup;
 				}
 			}
+			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 = call_consume_chunk(&ubuf[start], size, cbs);
+				if (unlikely(ret))
+					goto out_cleanup;
+
+				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_free_chunk_offsets;
-		} 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 == rdesc->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 (unlikely(ret))
+			goto read_error;
+	}
 	ret = 0;
-out_free_chunk_offsets:
+
+out_cleanup:
+	if (decompressor) {
+		wimlib_free_decompressor(rdesc->wim->decompressor);
+		rdesc->wim->decompressor = decompressor;
+		rdesc->wim->decompressor_ctype = ctype;
+		rdesc->wim->decompressor_max_block_size = chunk_size;
+	}
 	if (chunk_offsets_malloced)
 		FREE(chunk_offsets);
+	if (ubuf_malloced)
+		FREE(ubuf);
+	if (cbuf_malloced)
+		FREE(cbuf);
 	return ret;
 
+oom:
+	ERROR("Out of memory while reading compressed WIM resource");
+	ret = WIMLIB_ERR_NOMEM;
+	goto out_cleanup;
+
 read_error:
-	ERROR_WITH_ERRNO("Error reading compressed file resource");
-	goto out_free_chunk_offsets;
+	ERROR_WITH_ERRNO("Error reading data from WIM file");
+	goto out_cleanup;
 }
 
-/* Skip over the chunk table at the end of pipable, compressed resource being
- * read from a pipe.  */
+/* Read raw data from a file descriptor at the specified offset, feeding the
+ * data in nonempty chunks into the cbs->consume_chunk() function.  */
 static int
-skip_chunk_table(const struct wim_lookup_table_entry *lte,
-		 struct filedes *in_fd)
+read_raw_file_data(struct filedes *in_fd, u64 offset, u64 size,
+		   const struct read_blob_callbacks *cbs,
+		   const tchar *filename)
 {
-	u64 num_chunk_entries = wim_resource_chunks(lte) - 1;
-	u64 chunk_entry_size = (wim_resource_size(lte) > ((u64)1 << 32)) ? 8 : 4;
-	u64 chunk_table_size = num_chunk_entries * chunk_entry_size;
+	u8 buf[BUFFER_SIZE];
+	size_t bytes_to_read;
 	int ret;
 
-	if (num_chunk_entries != 0) {
-		u8 dummy;
-		ret = full_pread(in_fd, &dummy, 1,
-				 in_fd->offset + chunk_table_size - 1);
-		if (ret)
+	while (size) {
+		bytes_to_read = min(sizeof(buf), size);
+		ret = full_pread(in_fd, buf, bytes_to_read, offset);
+		if (unlikely(ret))
+			goto read_error;
+		ret = call_consume_chunk(buf, bytes_to_read, cbs);
+		if (unlikely(ret))
 			return ret;
+		size -= bytes_to_read;
+		offset += bytes_to_read;
 	}
 	return 0;
+
+read_error:
+	if (!filename) {
+		ERROR_WITH_ERRNO("Error reading data from WIM file");
+	} else if (ret == WIMLIB_ERR_UNEXPECTED_END_OF_FILE) {
+		ERROR("\"%"TS"\": File was concurrently truncated", filename);
+		ret = WIMLIB_ERR_CONCURRENT_MODIFICATION_DETECTED;
+	} else {
+		ERROR_WITH_ERRNO("\"%"TS"\": Error reading data", filename);
+	}
+	return ret;
 }
 
-/* Read and decompress data from a compressed, pipable resource being read from
- * a pipe.  */
+/* A consume_chunk() implementation that simply concatenates all chunks into an
+ * in-memory buffer.  */
 static int
-read_pipable_resource(const struct wim_lookup_table_entry *lte,
-		      u64 size, consume_data_callback_t cb,
-		      void *ctx_or_buf, int flags, u64 offset)
+bufferer_cb(const void *chunk, size_t size, void *_ctx)
 {
-	struct filedes *in_fd;
-	decompress_func_t decompress;
-	int ret;
-	u8 chunk[WIM_CHUNK_SIZE];
-	u8 cchunk[WIM_CHUNK_SIZE - 1];
-
-	/* Get pointers to appropriate decompression function and the input file
-	 * descriptor.  */
-	decompress = get_decompress_func(wim_resource_compression_type(lte));
-	in_fd = &lte->wim->in_fd;
-
-	/* This function currently assumes the entire resource is being read at
-	 * once and that the raw compressed data isn't being requested.  This is
-	 * based on the fact that this function currently only gets called
-	 * during the operation of wimlib_extract_image_from_pipe().  */
-	wimlib_assert(!(flags & WIMLIB_READ_RESOURCE_FLAG_RAW));
-	wimlib_assert(offset == 0);
-	wimlib_assert(size == wim_resource_size(lte));
-	wimlib_assert(in_fd->offset == lte->resource_entry.offset);
-
-	for (offset = 0; offset < size; offset += WIM_CHUNK_SIZE) {
-		struct pwm_chunk_hdr chunk_hdr;
-		u32 chunk_size;
-		u32 cchunk_size;
-		u8 *res_chunk;
-		u32 res_chunk_size;
-
-		/* Calculate uncompressed size of next chunk.  */
-		chunk_size = min(WIM_CHUNK_SIZE, size - offset);
-
-		/* Read the compressed size of the next chunk from the chunk
-		 * header.  */
-		ret = full_read(in_fd, &chunk_hdr, sizeof(chunk_hdr));
-		if (ret)
-			goto read_error;
-
-		cchunk_size = le32_to_cpu(chunk_hdr.compressed_size);
-
-		if (cchunk_size > WIM_CHUNK_SIZE) {
-			errno = EINVAL;
-			ret = WIMLIB_ERR_INVALID_PIPABLE_WIM;
-			goto invalid;
-		}
-
-		/* Read chunk data.  */
-		ret = full_read(in_fd, cchunk, cchunk_size);
-		if (ret)
-			goto read_error;
-
-		if (flags & WIMLIB_READ_RESOURCE_FLAG_SEEK_ONLY)
-			continue;
+	void **buf_p = _ctx;
 
-		/* Decompress chunk if needed.  Uncompressed size same
-		 * as compressed size means the chunk is uncompressed.
-		 */
-		res_chunk_size = chunk_size;
-		if (cchunk_size == chunk_size) {
-			res_chunk = cchunk;
-		} else {
-			ret = (*decompress)(cchunk, cchunk_size,
-					    chunk, chunk_size);
-			if (ret) {
-				errno = EINVAL;
-				ret = WIMLIB_ERR_DECOMPRESSION;
-				goto invalid;
-			}
-			res_chunk = chunk;
-		}
-
-		/* Feed the uncompressed data into the callback function or copy
-		 * it into the provided buffer.  */
-		if (cb) {
-			ret = cb(res_chunk, res_chunk_size, ctx_or_buf);
-			if (ret)
-				return ret;
-		} else {
-			ctx_or_buf = mempcpy(ctx_or_buf, res_chunk,
-					     res_chunk_size);
-		}
-	}
-
-	ret = skip_chunk_table(lte, in_fd);
-	if (ret)
-		goto read_error;
+	*buf_p = mempcpy(*buf_p, chunk, size);
 	return 0;
-
-read_error:
-	ERROR_WITH_ERRNO("Error reading compressed file resource");
-	return ret;
-
-invalid:
-	ERROR("Compressed file resource is invalid");
-	return ret;
 }
 
 /*
- * read_partial_wim_resource()-
- *
- * Read a range of data from a uncompressed or compressed resource in a WIM
- * file.  Data is written into a buffer or fed into a callback function, as
- * documented in read_resource_prefix().
- *
- * @flags can be:
- *
- * 0:
- *	Just do a normal read, decompressing the data if necessary.  @size and
- *	@offset are interpreted relative to the uncompressed contents of the
- *	stream.
- *
- * WIMLIB_READ_RESOURCE_FLAG_RAW_FULL:
- *	Only valid when the resource is compressed:  Read the raw contents of
- *	the compressed resource.  If the resource is non-pipable, this includes
- *	the chunk table as well as the compressed chunks.  If the resource is
- *	pipable, this includes the compressed chunks--- including the chunk
- *	headers--- and the chunk table.  The stream header is still *not*
- *	included.
- *
- *	In this mode, @offset is relative to the beginning of the raw contents
- *	of the compressed resource--- that is, the chunk table if the resource
- *	is non-pipable, or the header for the first compressed chunk if the
- *	resource is pipable.  @size is the number of raw bytes to read, which
- *	must not overrun the end of the resource.  For example, if @offset is 0,
- *	then @size can be at most the raw size of the compressed resource
- *	(@lte->resource_entry.size).
+ * Read @size bytes at @offset in the WIM resource described by @rdesc and feed
+ * the data into the @cbs->consume_chunk callback function.
  *
- * WIMLIB_READ_RESOURCE_FLAG_RAW_CHUNKS:
- *	Only valid when the resource is compressed and is not being read from a
- *	pipe:  Read the raw contents of the compressed chunks of the compressed
- *	resource.  For pipable resources, this does *not* include the chunk
- *	headers.  If a callback function is being used, it will be called once
- *	for each compressed chunk.  The chunk table is excluded.  Also, for
- *	pipable resources, the stream and chunk headers are excluded.  In this
- *	mode, @size must be exactly the raw size of the compressed resource
- *	(@lte->resource_entry.size) and @offset must be 0.
+ * @offset and @size are assumed to have already been validated against the
+ * resource's uncompressed size.
  *
- * WIMLIB_READ_RESOURCE_FLAG_SEEK_ONLY:
- *	Only valid when the resource is being read from a pipe:  Skip over the
- *	requested data rather than feed it to the callback function or write it
- *	into the buffer.  No decompression is done.
- *	WIMLIB_READ_RESOURCE_FLAG_RAW_* may not be combined with this flag.
- *	@offset must be 0 and @size must be the uncompressed size of the
- *	resource.
- *
- * Return values:
- *	WIMLIB_ERR_SUCCESS (0)
- *	WIMLIB_ERR_READ			(errno set)
- *	WIMLIB_ERR_NOMEM		(errno set to ENOMEM)
- *	WIMLIB_ERR_DECOMPRESSION	(errno set to EINVAL)
- *	WIMLIB_ERR_INVALID_PIPABLE_WIM  (errno set to EINVAL)
- *	
- *	or other error code returned by the @cb function.
+ * Returns 0 on success; or the first nonzero value returned by the callback
+ * function; or a nonzero wimlib error code with errno set as well.
  */
-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)
+static int
+read_partial_wim_resource(const struct wim_resource_descriptor *rdesc,
+			  const u64 offset, const u64 size,
+			  const struct read_blob_callbacks *cbs)
 {
-	struct filedes *in_fd;
-	int ret;
-
-	/* Make sure the resource is actually located in a WIM file and is not
-	 * somewhere else.  */
-	wimlib_assert(lte->resource_location == RESOURCE_IN_WIM);
-
-	/* Retrieve input file descriptor for the WIM file.  */
-	in_fd = &lte->wim->in_fd;
-
-	/* Don't allow raw reads (either full or chunks) of uncompressed
-	 * resources.  */
-	wimlib_assert(!(flags & WIMLIB_READ_RESOURCE_FLAG_RAW) ||
-		      resource_is_compressed(&lte->resource_entry));
-
-	/* Don't allow seek-only reads unless reading from a pipe; also don't
-	 * allow combining SEEK_ONLY with either RAW flag.  */
-	wimlib_assert(!(flags & WIMLIB_READ_RESOURCE_FLAG_SEEK_ONLY) ||
-		      (!filedes_is_seekable(in_fd) &&
-		       !(flags & WIMLIB_READ_RESOURCE_FLAG_RAW)));
-
-	DEBUG("Reading WIM resource: %"PRIu64" @ +%"PRIu64" "
-	      "from %"PRIu64" @ +%"PRIu64" (readflags 0x%08x, resflags 0x%02x%s)",
-	      size, offset,
-	      lte->resource_entry.original_size, lte->resource_entry.offset,
-	      flags, lte->resource_entry.flags,
-	      (lte->is_pipable ? ", pipable" : ""));
-
-	if ((flags & WIMLIB_READ_RESOURCE_FLAG_RAW_FULL) ||
-	    !resource_is_compressed(&lte->resource_entry))
+	if (rdesc->flags & (WIM_RESHDR_FLAG_COMPRESSED |
+			    WIM_RESHDR_FLAG_SOLID))
 	{
-		/* Reading raw resource contents or reading uncompressed
-		 * resource.  */
-		wimlib_assert(offset + size <= lte->resource_entry.size);
-		offset += lte->resource_entry.offset;
-		if (flags & WIMLIB_READ_RESOURCE_FLAG_SEEK_ONLY) {
-			if (lte->resource_entry.size != 0) {
-				u8 dummy;
-				ret = full_pread(in_fd, &dummy, 1,
-						 offset + lte->resource_entry.size - 1);
-				if (ret)
-					goto read_error;
-			}
-		} else 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);
-				ret = full_pread(in_fd, buf, bytes_to_read,
-						 offset);
-				if (ret)
-					goto read_error;
-				ret = cb(buf, bytes_to_read, ctx_or_buf);
-				if (ret)
-					goto out;
-				size -= bytes_to_read;
-				offset += bytes_to_read;
-			}
-		} else {
-			/* Send data directly to a buffer */
-			ret = full_pread(in_fd, ctx_or_buf, size, offset);
-			if (ret)
-				goto read_error;
-		}
-		ret = 0;
-	} else if (lte->is_pipable && !filedes_is_seekable(in_fd)) {
-		/* Reading compressed, pipable resource from pipe.  */
-		ret = read_pipable_resource(lte, size, cb,
-					    ctx_or_buf, flags, offset);
-	} else {
-		/* Reading compressed, possibly pipable resource from seekable
-		 * file.  */
-		ret = read_compressed_resource(lte, size, cb,
-					       ctx_or_buf, flags, offset);
+		/* Compressed resource  */
+		if (unlikely(!size))
+			return 0;
+		struct data_range range = {
+			.offset = offset,
+			.size = size,
+		};
+		return read_compressed_wim_resource(rdesc, &range, 1, cbs);
 	}
-	goto out;
 
-read_error:
-	ERROR_WITH_ERRNO("Error reading data from WIM");
-out:
-	return ret;
+	/* Uncompressed resource  */
+	return read_raw_file_data(&rdesc->wim->in_fd,
+				  rdesc->offset_in_wim + offset,
+				  size, cbs, NULL);
 }
 
+/* Read the specified range of uncompressed data from the specified blob, which
+ * must be located in a WIM file, into the specified buffer.  */
+int
+read_partial_wim_blob_into_buf(const struct blob_descriptor *blob,
+			       u64 offset, size_t size, void *buf)
+{
+	struct read_blob_callbacks cbs = {
+		.consume_chunk	= bufferer_cb,
+		.ctx		= &buf,
+	};
+	return read_partial_wim_resource(blob->rdesc,
+					 blob->offset_in_res + offset,
+					 size,
+					 &cbs);
+}
 
+/* Skip over the data of the specified WIM resource.  */
 int
-read_partial_wim_resource_into_buf(const struct wim_lookup_table_entry *lte,
-				   size_t size, u64 offset, void *buf)
+skip_wim_resource(const struct wim_resource_descriptor *rdesc)
 {
-	return read_partial_wim_resource(lte, size, NULL, buf, 0, offset);
+	struct read_blob_callbacks cbs = {
+	};
+	return read_partial_wim_resource(rdesc, 0,
+					 rdesc->uncompressed_size, &cbs);
 }
 
 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)
+read_wim_blob_prefix(const struct blob_descriptor *blob, u64 size,
+		     const struct read_blob_callbacks *cbs)
 {
-	return read_partial_wim_resource(lte, size, cb, ctx_or_buf, flags, 0);
+	return read_partial_wim_resource(blob->rdesc, blob->offset_in_res,
+					 size, cbs);
 }
 
-
-#ifndef __WIN32__
+/* This function handles reading blob 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 blob_descriptor *blob, u64 size,
+			 const struct read_blob_callbacks *cbs)
 {
-	const tchar *filename = lte->file_on_disk;
 	int ret;
-	struct filedes fd;
 	int raw_fd;
+	struct filedes fd;
 
-	DEBUG("Reading %"PRIu64" bytes from \"%"TS"\"",
-	      size, lte->file_on_disk);
-
-	raw_fd = open(filename, O_RDONLY);
-	if (raw_fd < 0) {
-		ERROR_WITH_ERRNO("Can't open \"%"TS"\"", filename);
+	raw_fd = topen(blob->file_on_disk, O_BINARY | O_RDONLY);
+	if (unlikely(raw_fd < 0)) {
+		ERROR_WITH_ERRNO("Can't open \"%"TS"\"", blob->file_on_disk);
 		return WIMLIB_ERR_OPEN;
 	}
 	filedes_init(&fd, raw_fd);
-	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);
-			ret = full_read(&fd, buf, bytes_to_read);
-			if (ret)
-				goto read_error;
-			ret = cb(buf, bytes_to_read, ctx_or_buf);
-			if (ret)
-				goto out_close;
-			size -= bytes_to_read;
-		}
-	} else {
-		/* Send data directly to a buffer */
-		ret = full_read(&fd, ctx_or_buf, size);
-		if (ret)
-			goto read_error;
-	}
-	ret = 0;
-	goto out_close;
-
-read_error:
-	ERROR_WITH_ERRNO("Error reading \"%"TS"\"", filename);
-out_close:
+	ret = read_raw_file_data(&fd, 0, size, cbs, blob->file_on_disk);
 	filedes_close(&fd);
 	return ret;
 }
-#endif /* !__WIN32__ */
 
+#ifdef WITH_FUSE
 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)
+read_staging_file_prefix(const struct blob_descriptor *blob, u64 size,
+			 const struct read_blob_callbacks *cbs)
 {
-	const void *inbuf = lte->attached_buffer;
+	int raw_fd;
+	struct filedes fd;
 	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);
+	raw_fd = openat(blob->staging_dir_fd, blob->staging_file_name,
+			O_RDONLY | O_NOFOLLOW);
+	if (unlikely(raw_fd < 0)) {
+		ERROR_WITH_ERRNO("Can't open staging file \"%s\"",
+				 blob->staging_file_name);
+		return WIMLIB_ERR_OPEN;
 	}
-	return 0;
+	filedes_init(&fd, raw_fd);
+	ret = read_raw_file_data(&fd, 0, size, cbs, blob->staging_file_name);
+	filedes_close(&fd);
+	return ret;
 }
+#endif
 
-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);
+/* This function handles the trivial case of reading blob data that is, in fact,
+ * already located in an in-memory buffer.  */
+static int
+read_buffer_prefix(const struct blob_descriptor *blob,
+		   u64 size, const struct read_blob_callbacks *cbs)
+{
+	if (unlikely(!size))
+		return 0;
+	return call_consume_chunk(blob->attached_buffer, size, cbs);
+}
+
+typedef int (*read_blob_prefix_handler_t)(const struct blob_descriptor *blob,
+					  u64 size,
+					  const struct read_blob_callbacks *cbs);
 
 /*
- * read_resource_prefix()-
- *
- * 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.
+ * Read the first @size bytes from a generic "blob", which may be located in any
+ * one of several locations, such as in a WIM resource (possibly compressed), in
+ * an external file, or directly in an in-memory buffer.  The blob data will be
+ * fed to the cbs->consume_chunk() callback function in chunks that are nonempty
+ * but otherwise are of unspecified size.
  *
- * If the resource is located in a WIM file, @flags can be set as documented in
- * read_partial_wim_resource().  Otherwise @flags are ignored.
+ * Returns 0 on success; nonzero on error.  A nonzero value will be returned if
+ * the blob data cannot be successfully read (for a number of different reasons,
+ * depending on the blob location), or if cbs->consume_chunk() 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_blob_prefix(const struct blob_descriptor *blob, u64 size,
+		 const struct read_blob_callbacks *cbs)
 {
-	static const read_resource_prefix_handler_t handlers[] = {
-		[RESOURCE_IN_WIM]             = read_wim_resource_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,
+	static const read_blob_prefix_handler_t handlers[] = {
+		[BLOB_IN_WIM] = read_wim_blob_prefix,
+		[BLOB_IN_FILE_ON_DISK] = read_file_on_disk_prefix,
+		[BLOB_IN_ATTACHED_BUFFER] = read_buffer_prefix,
 	#ifdef WITH_FUSE
-		[RESOURCE_IN_STAGING_FILE]    = read_file_on_disk_prefix,
+		[BLOB_IN_STAGING_FILE] = read_staging_file_prefix,
 	#endif
 	#ifdef WITH_NTFS_3G
-		[RESOURCE_IN_NTFS_VOLUME]     = read_ntfs_file_prefix,
+		[BLOB_IN_NTFS_VOLUME] = read_ntfs_attribute_prefix,
 	#endif
 	#ifdef __WIN32__
-		[RESOURCE_WIN32_ENCRYPTED]    = read_win32_encrypted_file_prefix,
+		[BLOB_IN_WINDOWS_FILE] = read_windows_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);
+	wimlib_assert(blob->blob_location < ARRAY_LEN(handlers)
+		      && handlers[blob->blob_location] != NULL);
+	wimlib_assert(size <= blob->size);
+	return handlers[blob->blob_location](blob, size, cbs);
+}
+
+/* Read the full data of the specified blob, passing the data into the specified
+ * callbacks (all of which are optional).  */
+int
+read_blob_with_cbs(struct blob_descriptor *blob,
+		   const struct read_blob_callbacks *cbs)
+{
+	int ret;
+
+	ret = call_begin_blob(blob, cbs);
+	if (unlikely(ret))
+		return ret;
+
+	ret = read_blob_prefix(blob, blob->size, cbs);
+
+	return call_end_blob(blob, ret, cbs);
 }
 
+/* Read the full uncompressed data of the specified blob into the specified
+ * buffer, which must have space for at least blob->size bytes.  The SHA-1
+ * message digest is *not* checked.  */
 int
-read_full_resource_into_buf(const struct wim_lookup_table_entry *lte,
-			    void *buf)
+read_blob_into_buf(const struct blob_descriptor *blob, void *buf)
 {
-	return read_resource_prefix(lte, wim_resource_size(lte), NULL, buf, 0);
+	struct read_blob_callbacks cbs = {
+		.consume_chunk	= bufferer_cb,
+		.ctx		= &buf,
+	};
+	return read_blob_prefix(blob, blob->size, &cbs);
 }
 
+/* Retrieve the full uncompressed data of the specified blob.  A buffer large
+ * enough hold the data is allocated and returned in @buf_ret.  The SHA-1
+ * message digest is *not* checked.  */
 int
-read_full_resource_into_alloc_buf(const struct wim_lookup_table_entry *lte,
-				  void **buf_ret)
+read_blob_into_alloc_buf(const struct blob_descriptor *blob, void **buf_ret)
 {
 	int ret;
 	void *buf;
 
-	if ((size_t)lte->resource_entry.original_size !=
-	    lte->resource_entry.original_size)
-	{
-		ERROR("Can't read %"PRIu64" byte resource into "
-		      "memory", lte->resource_entry.original_size);
+	if (unlikely((size_t)blob->size != blob->size)) {
+		ERROR("Can't read %"PRIu64" byte blob into memory", blob->size);
 		return WIMLIB_ERR_NOMEM;
 	}
 
-	buf = MALLOC(lte->resource_entry.original_size);
-	if (!buf)
+	buf = MALLOC(blob->size);
+	if (unlikely(!buf))
 		return WIMLIB_ERR_NOMEM;
 
-	ret = read_full_resource_into_buf(lte, buf);
-	if (ret) {
+	ret = read_blob_into_buf(blob, buf);
+	if (unlikely(ret)) {
 		FREE(buf);
 		return ret;
 	}
@@ -896,182 +806,565 @@ read_full_resource_into_alloc_buf(const struct wim_lookup_table_entry *lte,
 	return 0;
 }
 
+/* Retrieve the full uncompressed data of a WIM resource specified as a raw
+ * `wim_reshdr' and the corresponding WIM file.  A buffer large enough hold the
+ * data is allocated and returned in @buf_ret.  */
 int
-res_entry_to_data(const struct resource_entry *res_entry,
-		  WIMStruct *wim, void **buf_ret)
+wim_reshdr_to_data(const struct wim_reshdr *reshdr, WIMStruct *wim,
+		   void **buf_ret)
 {
+	struct wim_resource_descriptor rdesc;
+	struct blob_descriptor blob;
+
+	wim_reshdr_to_desc_and_blob(reshdr, wim, &rdesc, &blob);
+
+	return read_blob_into_alloc_buf(&blob, buf_ret);
+}
+
+/* Calculate the SHA-1 message digest of the uncompressed data of the specified
+ * WIM resource.  */
+int
+wim_reshdr_to_hash(const struct wim_reshdr *reshdr, WIMStruct *wim,
+		   u8 hash[SHA1_HASH_SIZE])
+{
+	struct wim_resource_descriptor rdesc;
+	struct blob_descriptor blob;
 	int ret;
-	struct wim_lookup_table_entry *lte;
 
-	lte = new_lookup_table_entry();
-	if (!lte)
-		return WIMLIB_ERR_NOMEM;
+	wim_reshdr_to_desc_and_blob(reshdr, wim, &rdesc, &blob);
+	blob.unhashed = 1;
 
-	copy_resource_entry(&lte->resource_entry, res_entry);
-	lte->unhashed = 1;
-	lte->part_number = wim->hdr.part_number;
-	lte_init_wim(lte, wim);
+	ret = sha1_blob(&blob);
+	if (unlikely(ret))
+		return ret;
 
-	ret = read_full_resource_into_alloc_buf(lte, buf_ret);
-	free_lookup_table_entry(lte);
-	return ret;
+	copy_hash(hash, blob.hash);
+	return 0;
 }
 
-struct extract_ctx {
+struct blobifier_context {
+	struct read_blob_callbacks cbs;
+	struct blob_descriptor *cur_blob;
+	struct blob_descriptor *next_blob;
+	u64 cur_blob_offset;
+	struct blob_descriptor *final_blob;
+	size_t list_head_offset;
+};
+
+static struct blob_descriptor *
+next_blob(struct blob_descriptor *blob, size_t list_head_offset)
+{
+	struct list_head *cur;
+
+	cur = (struct list_head*)((u8*)blob + list_head_offset);
+
+	return (struct blob_descriptor*)((u8*)cur->next - list_head_offset);
+}
+
+/* A consume_chunk() implementation that translates raw resource data into
+ * blobs, calling the begin_blob, consume_chunk, and end_blob callbacks as
+ * appropriate.  */
+static int
+blobifier_cb(const void *chunk, size_t size, void *_ctx)
+{
+	struct blobifier_context *ctx = _ctx;
+	int ret;
+
+	wimlib_assert(ctx->cur_blob != NULL);
+	wimlib_assert(size <= ctx->cur_blob->size - ctx->cur_blob_offset);
+
+	if (ctx->cur_blob_offset == 0) {
+		/* Starting a new blob.  */
+		ret = call_begin_blob(ctx->cur_blob, &ctx->cbs);
+		if (ret)
+			return ret;
+	}
+
+	ctx->cur_blob_offset += size;
+
+	ret = call_consume_chunk(chunk, size, &ctx->cbs);
+	if (ret)
+		return ret;
+
+	if (ctx->cur_blob_offset == ctx->cur_blob->size) {
+		/* Finished reading all the data for a blob.  */
+
+		ctx->cur_blob_offset = 0;
+
+		ret = call_end_blob(ctx->cur_blob, 0, &ctx->cbs);
+		if (ret)
+			return ret;
+
+		/* Advance to next blob.  */
+		ctx->cur_blob = ctx->next_blob;
+		if (ctx->cur_blob != NULL) {
+			if (ctx->cur_blob != ctx->final_blob)
+				ctx->next_blob = next_blob(ctx->cur_blob,
+							   ctx->list_head_offset);
+			else
+				ctx->next_blob = NULL;
+		}
+	}
+	return 0;
+}
+
+struct hasher_context {
 	SHA_CTX sha_ctx;
-	consume_data_callback_t extract_chunk;
-	void *extract_chunk_arg;
+	int flags;
+	struct read_blob_callbacks cbs;
 };
 
+/* Callback for starting to read a blob while calculating its SHA-1 message
+ * digest.  */
+static int
+hasher_begin_blob(struct blob_descriptor *blob, void *_ctx)
+{
+	struct hasher_context *ctx = _ctx;
+
+	sha1_init(&ctx->sha_ctx);
+
+	return call_begin_blob(blob, &ctx->cbs);
+}
+
+/* A consume_chunk() implementation that continues calculating the SHA-1 message
+ * digest of the blob being read, then optionally passes the data on to another
+ * consume_chunk() implementation.  This allows checking the SHA-1 message
+ * digest of a blob being extracted, for example.  */
+static int
+hasher_consume_chunk(const void *chunk, size_t size, void *_ctx)
+{
+	struct hasher_context *ctx = _ctx;
+
+	sha1_update(&ctx->sha_ctx, chunk, size);
+
+	return call_consume_chunk(chunk, size, &ctx->cbs);
+}
+
+static int
+report_sha1_mismatch_error(const struct blob_descriptor *blob,
+			   const u8 actual_hash[SHA1_HASH_SIZE])
+{
+	tchar expected_hashstr[SHA1_HASH_SIZE * 2 + 1];
+	tchar actual_hashstr[SHA1_HASH_SIZE * 2 + 1];
+
+	wimlib_assert(blob->blob_location != BLOB_NONEXISTENT);
+	wimlib_assert(blob->blob_location != BLOB_IN_ATTACHED_BUFFER);
+
+	sprint_hash(blob->hash, expected_hashstr);
+	sprint_hash(actual_hash, actual_hashstr);
+
+	if (blob_is_in_file(blob)) {
+		ERROR("A file was concurrently modified!\n"
+		      "        Path: \"%"TS"\"\n"
+		      "        Expected SHA-1: %"TS"\n"
+		      "        Actual SHA-1: %"TS"\n",
+		      blob_file_path(blob), expected_hashstr, actual_hashstr);
+		return WIMLIB_ERR_CONCURRENT_MODIFICATION_DETECTED;
+	} else if (blob->blob_location == BLOB_IN_WIM) {
+		const struct wim_resource_descriptor *rdesc = blob->rdesc;
+		ERROR("A WIM resource is corrupted!\n"
+		      "        WIM file: \"%"TS"\"\n"
+		      "        Blob uncompressed size: %"PRIu64"\n"
+		      "        Resource offset in WIM: %"PRIu64"\n"
+		      "        Resource uncompressed size: %"PRIu64"\n"
+		      "        Resource size in WIM: %"PRIu64"\n"
+		      "        Resource flags: 0x%x%"TS"\n"
+		      "        Resource compression type: %"TS"\n"
+		      "        Resource compression chunk size: %"PRIu32"\n"
+		      "        Expected SHA-1: %"TS"\n"
+		      "        Actual SHA-1: %"TS"\n",
+		      rdesc->wim->filename,
+		      blob->size,
+		      rdesc->offset_in_wim,
+		      rdesc->uncompressed_size,
+		      rdesc->size_in_wim,
+		      (unsigned int)rdesc->flags,
+		      (rdesc->is_pipable ? T(", pipable") : T("")),
+		      wimlib_get_compression_type_string(
+						rdesc->compression_type),
+		      rdesc->chunk_size,
+		      expected_hashstr, actual_hashstr);
+		return WIMLIB_ERR_INVALID_RESOURCE_HASH;
+	} else {
+		ERROR("File data was concurrently modified!\n"
+		      "        Location ID: %d\n"
+		      "        Expected SHA-1: %"TS"\n"
+		      "        Actual SHA-1: %"TS"\n",
+		      (int)blob->blob_location,
+		      expected_hashstr, actual_hashstr);
+		return WIMLIB_ERR_CONCURRENT_MODIFICATION_DETECTED;
+	}
+}
+
+/* Callback for finishing reading a blob while calculating its SHA-1 message
+ * digest.  */
 static int
-extract_chunk_sha1_wrapper(const void *chunk, size_t chunk_size,
-			   void *_ctx)
+hasher_end_blob(struct blob_descriptor *blob, int status, void *_ctx)
 {
-	struct extract_ctx *ctx = _ctx;
+	struct hasher_context *ctx = _ctx;
+	u8 hash[SHA1_HASH_SIZE];
+	int ret;
+
+	if (unlikely(status)) {
+		/* Error occurred; the full blob may not have been read.  */
+		ret = status;
+		goto out_next_cb;
+	}
+
+	/* Retrieve the final SHA-1 message digest.  */
+	sha1_final(hash, &ctx->sha_ctx);
+
+	/* Set the SHA-1 message digest of the blob, or compare the calculated
+	 * value with stored value.  */
+	if (blob->unhashed) {
+		if (ctx->flags & COMPUTE_MISSING_BLOB_HASHES)
+			copy_hash(blob->hash, hash);
+	} else if ((ctx->flags & VERIFY_BLOB_HASHES) &&
+		   unlikely(!hashes_equal(hash, blob->hash)))
+	{
+		ret = report_sha1_mismatch_error(blob, hash);
+		goto out_next_cb;
+	}
+	ret = 0;
+out_next_cb:
+	return call_end_blob(blob, ret, &ctx->cbs);
+}
+
+/* Read the full data of the specified blob, passing the data into the specified
+ * callbacks (all of which are optional) and either checking or computing the
+ * SHA-1 message digest of the blob.  */
+int
+read_blob_with_sha1(struct blob_descriptor *blob,
+		    const struct read_blob_callbacks *cbs)
+{
+	struct hasher_context hasher_ctx = {
+		.flags = VERIFY_BLOB_HASHES | COMPUTE_MISSING_BLOB_HASHES,
+		.cbs = *cbs,
+	};
+	struct read_blob_callbacks hasher_cbs = {
+		.begin_blob	= hasher_begin_blob,
+		.consume_chunk	= hasher_consume_chunk,
+		.end_blob	= hasher_end_blob,
+		.ctx		= &hasher_ctx,
+	};
+	return read_blob_with_cbs(blob, &hasher_cbs);
+}
+
+static int
+read_blobs_in_solid_resource(struct blob_descriptor *first_blob,
+			     struct blob_descriptor *last_blob,
+			     size_t blob_count,
+			     size_t list_head_offset,
+			     const struct read_blob_callbacks *sink_cbs)
+{
+	struct data_range *ranges;
+	bool ranges_malloced;
+	struct blob_descriptor *cur_blob;
+	size_t i;
+	int ret;
+	u64 ranges_alloc_size;
+
+	/* Setup data ranges array (one range per blob to read); this way
+	 * read_compressed_wim_resource() does not need to be aware of blobs.
+	 */
+
+	ranges_alloc_size = (u64)blob_count * sizeof(ranges[0]);
 
-	sha1_update(&ctx->sha_ctx, chunk, chunk_size);
-	return ctx->extract_chunk(chunk, chunk_size, ctx->extract_chunk_arg);
+	if (unlikely((size_t)ranges_alloc_size != ranges_alloc_size))
+		goto oom;
+
+	if (ranges_alloc_size <= STACK_MAX) {
+		ranges = alloca(ranges_alloc_size);
+		ranges_malloced = false;
+	} else {
+		ranges = MALLOC(ranges_alloc_size);
+		if (unlikely(!ranges))
+			goto oom;
+		ranges_malloced = true;
+	}
+
+	for (i = 0, cur_blob = first_blob;
+	     i < blob_count;
+	     i++, cur_blob = next_blob(cur_blob, list_head_offset))
+	{
+		ranges[i].offset = cur_blob->offset_in_res;
+		ranges[i].size = cur_blob->size;
+	}
+
+	struct blobifier_context blobifier_ctx = {
+		.cbs			= *sink_cbs,
+		.cur_blob		= first_blob,
+		.next_blob		= next_blob(first_blob, list_head_offset),
+		.cur_blob_offset	= 0,
+		.final_blob		= last_blob,
+		.list_head_offset	= list_head_offset,
+	};
+	struct read_blob_callbacks cbs = {
+		.consume_chunk	= blobifier_cb,
+		.ctx		= &blobifier_ctx,
+	};
+
+	ret = read_compressed_wim_resource(first_blob->rdesc, ranges,
+					   blob_count, &cbs);
+
+	if (ranges_malloced)
+		FREE(ranges);
+
+	if (unlikely(ret && blobifier_ctx.cur_blob_offset != 0)) {
+		ret = call_end_blob(blobifier_ctx.cur_blob, ret,
+				    &blobifier_ctx.cbs);
+	}
+	return ret;
+
+oom:
+	ERROR("Too many blobs in one resource!");
+	return WIMLIB_ERR_NOMEM;
 }
 
-/* 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.
+/*
+ * Read a list of blobs, each of which may be in any supported location (e.g.
+ * in a WIM or in an external file).  This function optimizes the case where
+ * multiple blobs are combined into a single solid compressed WIM resource by
+ * reading the blobs in sequential order, only decompressing the solid resource
+ * one time.
+ *
+ * @blob_list
+ *	List of blobs to read.
+ * @list_head_offset
+ *	Offset of the `struct list_head' within each `struct blob_descriptor'
+ *	that makes up the @blob_list.
+ * @cbs
+ *	Callback functions to accept the blob data.
+ * @flags
+ *	Bitwise OR of zero or more of the following flags:
+ *
+ *	VERIFY_BLOB_HASHES:
+ *		For all blobs being read that have already had SHA-1 message
+ *		digests computed, calculate the SHA-1 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.
  *
- * @extract_chunk is a function that is called to extract each chunk of the
- * resource. */
+ *	COMPUTE_MISSING_BLOB_HASHES
+ *		For all blobs being read that have not yet had their SHA-1
+ *		message digests computed, calculate and save their SHA-1 message
+ *		digests.
+ *
+ *	BLOB_LIST_ALREADY_SORTED
+ *		@blob_list is already sorted in sequential order for reading.
+ *
+ * The callback functions are allowed to delete the current blob 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
-extract_wim_resource(const struct wim_lookup_table_entry *lte,
-		     u64 size,
-		     consume_data_callback_t extract_chunk,
-		     void *extract_chunk_arg)
+read_blob_list(struct list_head *blob_list, size_t list_head_offset,
+	       const struct read_blob_callbacks *cbs, int flags)
 {
 	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)) {
-				if (wimlib_print_errors) {
-					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!");
-				}
-				ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
+	struct list_head *cur, *next;
+	struct blob_descriptor *blob;
+	struct hasher_context *hasher_ctx;
+	struct read_blob_callbacks *sink_cbs;
+
+	if (!(flags & BLOB_LIST_ALREADY_SORTED)) {
+		ret = sort_blob_list_by_sequential_order(blob_list,
+							 list_head_offset);
+		if (ret)
+			return ret;
+	}
+
+	if (flags & (VERIFY_BLOB_HASHES | COMPUTE_MISSING_BLOB_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_blob_callbacks) {
+			.begin_blob	= hasher_begin_blob,
+			.consume_chunk	= hasher_consume_chunk,
+			.end_blob	= hasher_end_blob,
+			.ctx		= hasher_ctx,
+		};
+	} else {
+		sink_cbs = (struct read_blob_callbacks *)cbs;
+	}
+
+	for (cur = blob_list->next, next = cur->next;
+	     cur != blob_list;
+	     cur = next, next = cur->next)
+	{
+		blob = (struct blob_descriptor*)((u8*)cur - list_head_offset);
+
+		if (blob->blob_location == BLOB_IN_WIM &&
+		    blob->size != blob->rdesc->uncompressed_size)
+		{
+			struct blob_descriptor *blob_next, *blob_last;
+			struct list_head *next2;
+			size_t blob_count;
+
+			/* The next blob is a proper sub-sequence of a WIM
+			 * resource.  See if there are other blobs in the same
+			 * resource that need to be read.  Since
+			 * sort_blob_list_by_sequential_order() sorted the blobs
+			 * by offset in the WIM, this can be determined by
+			 * simply scanning forward in the list.  */
+
+			blob_last = blob;
+			blob_count = 1;
+			for (next2 = next;
+			     next2 != blob_list
+			     && (blob_next = (struct blob_descriptor*)
+						((u8*)next2 - list_head_offset),
+				 blob_next->blob_location == BLOB_IN_WIM
+				 && blob_next->rdesc == blob->rdesc);
+			     next2 = next2->next)
+			{
+				blob_last = blob_next;
+				blob_count++;
+			}
+			if (blob_count > 1) {
+				/* Reading multiple blobs combined into a single
+				 * WIM resource.  They are in the blob list,
+				 * sorted by offset; @blob specifies the first
+				 * blob in the resource that needs to be read
+				 * and @blob_last specifies the last blob in the
+				 * resource that needs to be read.  */
+				next = next2;
+				ret = read_blobs_in_solid_resource(blob, blob_last,
+								   blob_count,
+								   list_head_offset,
+								   sink_cbs);
+				if (ret)
+					return ret;
+				continue;
 			}
 		}
-	} else {
-		/* Don't do SHA1 */
-		ret = read_resource_prefix(lte, size, extract_chunk,
-					   extract_chunk_arg, 0);
+
+		ret = read_blob_with_cbs(blob, sink_cbs);
+		if (unlikely(ret && ret != BEGIN_BLOB_STATUS_SKIP_BLOB))
+			return ret;
 	}
-	return ret;
+	return 0;
 }
 
 static int
-extract_wim_chunk_to_fd(const void *buf, size_t len, void *_fd_p)
+extract_chunk_to_fd(const void *chunk, size_t size, void *_fd)
 {
-	struct filedes *fd = _fd_p;
-	int ret = full_write(fd, buf, len);
-	if (ret)
+	struct filedes *fd = _fd;
+	int ret = full_write(fd, chunk, size);
+	if (unlikely(ret))
 		ERROR_WITH_ERRNO("Error writing to file descriptor");
 	return ret;
 }
 
+/* Extract the first @size bytes of the specified blob to the specified file
+ * descriptor.  This does *not* check the SHA-1 message digest.  */
 int
-extract_wim_resource_to_fd(const struct wim_lookup_table_entry *lte,
-			   struct filedes *fd, u64 size)
+extract_blob_prefix_to_fd(struct blob_descriptor *blob, u64 size,
+			  struct filedes *fd)
 {
-	return extract_wim_resource(lte, size, extract_wim_chunk_to_fd, fd);
+	struct read_blob_callbacks cbs = {
+		.consume_chunk	= extract_chunk_to_fd,
+		.ctx		= fd,
+	};
+	return read_blob_prefix(blob, size, &cbs);
 }
 
-
-static int
-sha1_chunk(const void *buf, size_t len, void *ctx)
+/* Extract the full uncompressed contents of the specified blob to the specified
+ * file descriptor.  This checks the SHA-1 message digest.  */
+int
+extract_blob_to_fd(struct blob_descriptor *blob, struct filedes *fd)
 {
-	sha1_update(ctx, buf, len);
-	return 0;
+	struct read_blob_callbacks cbs = {
+		.consume_chunk	= extract_chunk_to_fd,
+		.ctx		= fd,
+	};
+	return read_blob_with_sha1(blob, &cbs);
 }
 
-/* Calculate the SHA1 message digest of a stream. */
+/* Calculate the SHA-1 message digest of a blob and store it in @blob->hash.  */
 int
-sha1_resource(struct wim_lookup_table_entry *lte)
+sha1_blob(struct blob_descriptor *blob)
 {
-	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;
+	struct read_blob_callbacks cbs = {
+	};
+	return read_blob_with_sha1(blob, &cbs);
 }
 
-/* Translates a WIM resource entry from the on-disk format to an in-memory
- * format. */
+/*
+ * Convert a short WIM resource header to a stand-alone WIM resource descriptor.
+ *
+ * Note: for solid resources some fields still need to be overridden.
+ */
 void
-get_resource_entry(const struct resource_entry_disk *disk_entry,
-		   struct resource_entry *entry)
+wim_reshdr_to_desc(const struct wim_reshdr *reshdr, WIMStruct *wim,
+		   struct wim_resource_descriptor *rdesc)
 {
-	/* Note: disk_entry may not be 8 byte aligned--- in that case, the
-	 * offset and original_size members will be unaligned.  (This should be
-	 * okay since `struct resource_entry_disk' is declared as packed.) */
-
-	/* Read the size and flags into a bitfield portably... */
-	entry->size = (((u64)disk_entry->size[0] <<  0) |
-		       ((u64)disk_entry->size[1] <<  8) |
-		       ((u64)disk_entry->size[2] << 16) |
-		       ((u64)disk_entry->size[3] << 24) |
-		       ((u64)disk_entry->size[4] << 32) |
-		       ((u64)disk_entry->size[5] << 40) |
-		       ((u64)disk_entry->size[6] << 48));
-	entry->flags = disk_entry->flags;
-	entry->offset = le64_to_cpu(disk_entry->offset);
-	entry->original_size = le64_to_cpu(disk_entry->original_size);
-
-	/* 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... */
-	if (entry->offset & 0xc000000000000000ULL) {
-		WARNING("Truncating offset in resource entry");
-		entry->offset &= 0x3fffffffffffffffULL;
-	}
-	if (entry->original_size & 0xc000000000000000ULL) {
-		WARNING("Truncating original_size in resource entry");
-		entry->original_size &= 0x3fffffffffffffffULL;
+	rdesc->wim = wim;
+	rdesc->offset_in_wim = reshdr->offset_in_wim;
+	rdesc->size_in_wim = reshdr->size_in_wim;
+	rdesc->uncompressed_size = reshdr->uncompressed_size;
+	INIT_LIST_HEAD(&rdesc->blob_list);
+	rdesc->flags = reshdr->flags;
+	rdesc->is_pipable = wim_is_pipable(wim);
+	if (rdesc->flags & WIM_RESHDR_FLAG_COMPRESSED) {
+		rdesc->compression_type = wim->compression_type;
+		rdesc->chunk_size = wim->chunk_size;
+	} else {
+		rdesc->compression_type = WIMLIB_COMPRESSION_TYPE_NONE;
+		rdesc->chunk_size = 0;
 	}
 }
 
-/* Translates a WIM resource entry from an in-memory format into the on-disk
- * format. */
+/*
+ * Convert the short WIM resource header @reshdr to a stand-alone WIM resource
+ * descriptor @rdesc, then set @blob to consist of that entire resource.  This
+ * should only be used for non-solid resources!
+ */
+void
+wim_reshdr_to_desc_and_blob(const struct wim_reshdr *reshdr, WIMStruct *wim,
+			    struct wim_resource_descriptor *rdesc,
+			    struct blob_descriptor *blob)
+{
+	wim_reshdr_to_desc(reshdr, wim, rdesc);
+	blob->size = rdesc->uncompressed_size;
+	blob_set_is_located_in_wim_resource(blob, rdesc, 0);
+}
+
+/* Import a WIM resource header from the on-disk 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;
+}
+
+/* Export a WIM resource header to the on-disk format.  */
 void
-put_resource_entry(const struct resource_entry *entry,
-		   struct resource_entry_disk *disk_entry)
+put_wim_reshdr(const struct wim_reshdr *reshdr,
+	       struct wim_reshdr_disk *disk_reshdr)
 {
-	/* Note: disk_entry may not be 8 byte aligned--- in that case, the
-	 * offset and original_size members will be unaligned.  (This should be
-	 * okay since `struct resource_entry_disk' is declared as packed.) */
-	u64 size = entry->size;
-
-	disk_entry->size[0] = size >>  0;
-	disk_entry->size[1] = size >>  8;
-	disk_entry->size[2] = size >> 16;
-	disk_entry->size[3] = size >> 24;
-	disk_entry->size[4] = size >> 32;
-	disk_entry->size[5] = size >> 40;
-	disk_entry->size[6] = size >> 48;
-	disk_entry->flags = entry->flags;
-	disk_entry->offset = cpu_to_le64(entry->offset);
-	disk_entry->original_size = cpu_to_le64(entry->original_size);
+	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);
 }