6 * Copyright (C) 2012, 2013 Eric Biggers
8 * This file is part of wimlib, a library for working with WIM files.
10 * wimlib is free software; you can redistribute it and/or modify it under the
11 * terms of the GNU General Public License as published by the Free Software
12 * Foundation; either version 3 of the License, or (at your option) any later
15 * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
16 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
17 * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License along with
20 * wimlib; if not, see http://www.gnu.org/licenses/.
27 #include "wimlib/dentry.h"
28 #include "wimlib/error.h"
29 #include "wimlib/file_io.h"
30 #include "wimlib/lookup_table.h"
31 #include "wimlib/metadata.h"
32 #include "wimlib/resource.h"
33 #include "wimlib/security.h"
36 * Reads a metadata resource for an image in the WIM file. The metadata
37 * resource consists of the security data, followed by the directory entry for
38 * the root directory, followed by all the other directory entries in the
39 * filesystem. The subdir_offset field of each directory entry gives the start
40 * of its child entries from the beginning of the metadata resource. An
41 * end-of-directory is signaled by a directory entry of length '0', really of
42 * length 8, because that's how long the 'length' field is.
45 * Pointer to the WIMStruct for the WIM file.
48 * Pointer to the image metadata structure for the image whose metadata
49 * resource we are reading. Its `metadata_lte' member specifies the lookup
50 * table entry for the metadata resource. The rest of the image metadata
51 * entry will be filled in by this function.
54 * WIMLIB_ERR_SUCCESS (0)
55 * WIMLIB_ERR_INVALID_METADATA_RESOURCE
58 * WIMLIB_ERR_UNEXPECTED_END_OF_FILE
59 * WIMLIB_ERR_DECOMPRESSION
62 read_metadata_resource(WIMStruct *wim, struct wim_image_metadata *imd)
66 struct wim_dentry *root;
67 const struct wim_lookup_table_entry *metadata_lte;
69 u8 hash[SHA1_HASH_SIZE];
70 struct wim_security_data *security_data;
71 struct wim_inode *inode;
73 metadata_lte = imd->metadata_lte;
74 metadata_len = wim_resource_size(metadata_lte);
76 DEBUG("Reading metadata resource: original_size = %"PRIu64", "
77 "size = %"PRIu64", offset = %"PRIu64"",
78 metadata_lte->resource_entry.original_size,
79 metadata_lte->resource_entry.size,
80 metadata_lte->resource_entry.offset);
82 /* There is no way the metadata resource could possibly be less than (8
83 * + WIM_DENTRY_DISK_SIZE) bytes, where the 8 is for security data (with
84 * no security descriptors) and WIM_DENTRY_DISK_SIZE is for the root
86 if (metadata_len < 8 + WIM_DENTRY_DISK_SIZE) {
87 ERROR("Expected at least %u bytes for the metadata resource",
88 8 + WIM_DENTRY_DISK_SIZE);
89 return WIMLIB_ERR_INVALID_METADATA_RESOURCE;
92 /* Read the metadata resource into memory. (It may be compressed.) */
93 ret = read_full_resource_into_alloc_buf(metadata_lte, &buf);
97 if (!metadata_lte->dont_check_metadata_hash) {
98 sha1_buffer(buf, metadata_len, hash);
99 if (!hashes_equal(metadata_lte->hash, hash)) {
100 ERROR("Metadata resource is corrupted "
101 "(invalid SHA-1 message digest)!");
102 ret = WIMLIB_ERR_INVALID_METADATA_RESOURCE;
107 DEBUG("Finished reading metadata resource into memory.");
109 ret = read_wim_security_data(buf, metadata_len, &security_data);
113 DEBUG("Reading root dentry");
115 /* Allocate memory for the root dentry and read it into memory */
116 root = MALLOC(sizeof(struct wim_dentry));
118 ret = WIMLIB_ERR_NOMEM;
119 goto out_free_security_data;
122 /* The root directory entry starts after security data, aligned on an
123 * 8-byte boundary within the metadata resource. Since
124 * security_data->total_length was already rounded up to an 8-byte
125 * boundary, its value can be used as the offset of the root directory
127 ret = read_dentry(buf, metadata_len,
128 security_data->total_length, root);
130 if (ret == 0 && root->length == 0) {
131 WARNING("Metadata resource begins with end-of-directory entry "
132 "(treating as empty image)");
140 goto out_free_security_data;
143 if (dentry_has_long_name(root) || dentry_has_short_name(root)) {
144 WARNING("The root directory has a nonempty name (removing it)");
145 FREE(root->file_name);
146 FREE(root->short_name);
147 root->file_name = NULL;
148 root->short_name = NULL;
149 root->file_name_nbytes = 0;
150 root->short_name_nbytes = 0;
153 if (!dentry_is_directory(root)) {
154 ERROR("Root of the WIM image must be a directory!");
156 ret = WIMLIB_ERR_INVALID_METADATA_RESOURCE;
157 goto out_free_security_data;
160 /* This is the root dentry, so set its parent to itself. */
163 inode_add_dentry(root, root->d_inode);
165 /* Now read the entire directory entry tree into memory. */
166 DEBUG("Reading dentry tree");
167 ret = read_dentry_tree(buf, metadata_len, root);
169 goto out_free_dentry_tree;
171 /* Build hash table that maps hard link group IDs to dentry sets */
172 ret = dentry_tree_fix_inodes(root, &imd->inode_list);
174 goto out_free_dentry_tree;
177 DEBUG("Running miscellaneous verifications on the dentry tree");
178 image_for_each_inode(inode, imd) {
179 ret = verify_inode(inode, security_data);
181 goto out_free_dentry_tree;
183 DEBUG("Done reading image metadata");
185 imd->root_dentry = root;
186 imd->security_data = security_data;
187 INIT_LIST_HEAD(&imd->unhashed_streams);
190 out_free_dentry_tree:
191 free_dentry_tree(root, wim->lookup_table);
192 out_free_security_data:
193 free_wim_security_data(security_data);
200 recalculate_security_data_length(struct wim_security_data *sd)
202 u32 total_length = sizeof(u64) * sd->num_entries + 2 * sizeof(u32);
203 for (u32 i = 0; i < sd->num_entries; i++)
204 total_length += sd->sizes[i];
205 sd->total_length = (total_length + 7) & ~7;
209 prepare_metadata_resource(WIMStruct *wim, int image,
210 u8 **buf_ret, size_t *len_ret)
216 struct wim_dentry *root;
218 struct wim_security_data *sd;
219 struct wim_image_metadata *imd;
221 DEBUG("Preparing metadata resource for image %d", image);
223 ret = select_wim_image(wim, image);
227 imd = wim->image_metadata[image - 1];
229 root = imd->root_dentry;
230 sd = imd->security_data;
233 /* Empty image; create a dummy root. */
234 ret = new_filler_directory(T(""), &root);
237 imd->root_dentry = root;
240 /* Offset of first child of the root dentry. It's equal to:
241 * - The total length of the security data, rounded to the next 8-byte
243 * - plus the total length of the root dentry,
244 * - plus 8 bytes for an end-of-directory entry following the root
245 * dentry (shouldn't really be needed, but just in case...)
247 recalculate_security_data_length(sd);
248 subdir_offset = (((u64)sd->total_length + 7) & ~7) +
249 dentry_out_total_length(root) + 8;
251 /* Calculate the subdirectory offsets for the entire dentry tree. */
252 calculate_subdir_offsets(root, &subdir_offset);
254 /* Total length of the metadata resource (uncompressed). */
257 /* Allocate a buffer to contain the uncompressed metadata resource. */
260 ERROR("Failed to allocate %"PRIu64" bytes for "
261 "metadata resource", len);
262 return WIMLIB_ERR_NOMEM;
265 /* Write the security data into the resource buffer. */
266 p = write_wim_security_data(sd, buf);
268 /* Write the dentry tree into the resource buffer. */
269 p = write_dentry_tree(root, p);
271 /* We MUST have exactly filled the buffer; otherwise we calculated its
272 * size incorrectly or wrote the data incorrectly. */
273 wimlib_assert(p - buf == len);
281 write_metadata_resource(WIMStruct *wim, int image, int write_resource_flags)
286 struct wim_image_metadata *imd;
288 ret = prepare_metadata_resource(wim, image, &buf, &len);
292 imd = wim->image_metadata[image - 1];
294 /* Write the metadata resource to the output WIM using the proper
295 * compression type, in the process updating the lookup table entry for
296 * the metadata resource. */
297 ret = write_wim_resource_from_buffer(buf, len, WIM_RESHDR_FLAG_METADATA,
299 wim->out_compression_type,
301 &imd->metadata_lte->output_resource_entry,
302 imd->metadata_lte->hash,
303 write_resource_flags,
306 /* Original checksum was overridden; set a flag so it isn't used. */
307 imd->metadata_lte->dont_check_metadata_hash = 1;