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.
44 * @w: Pointer to the WIMStruct for the WIM file.
46 * @imd: Pointer to the image metadata structure for the image whose
47 * metadata resource we are reading. Its `metadata_lte' member
48 * specifies the lookup table entry for the metadata resource. The
49 * rest of the image metadata entry will be filled in by this
52 * Returns: Zero on success, nonzero on failure.
55 read_metadata_resource(WIMStruct *wim, struct wim_image_metadata *imd)
59 struct wim_dentry *root;
60 const struct wim_lookup_table_entry *metadata_lte;
62 u8 hash[SHA1_HASH_SIZE];
63 struct wim_security_data *security_data;
64 struct wim_inode *inode;
66 metadata_lte = imd->metadata_lte;
67 metadata_len = wim_resource_size(metadata_lte);
69 DEBUG("Reading metadata resource: original_size = %"PRIu64", "
70 "size = %"PRIu64", offset = %"PRIu64"",
71 metadata_lte->resource_entry.original_size,
72 metadata_lte->resource_entry.size,
73 metadata_lte->resource_entry.offset);
75 /* There is no way the metadata resource could possibly be less than (8
76 * + WIM_DENTRY_DISK_SIZE) bytes, where the 8 is for security data (with
77 * no security descriptors) and WIM_DENTRY_DISK_SIZE is for the root
79 if (metadata_len < 8 + WIM_DENTRY_DISK_SIZE) {
80 ERROR("Expected at least %u bytes for the metadata resource",
81 8 + WIM_DENTRY_DISK_SIZE);
82 return WIMLIB_ERR_INVALID_RESOURCE_SIZE;
85 if (sizeof(size_t) < 8 && metadata_len > 0xffffffff) {
86 ERROR("Metadata resource is too large (%"PRIu64" bytes",
88 return WIMLIB_ERR_INVALID_RESOURCE_SIZE;
91 /* Allocate memory for the uncompressed metadata resource. */
92 buf = MALLOC(metadata_len);
95 ERROR("Failed to allocate %"PRIu64" bytes for uncompressed "
96 "metadata resource", metadata_len);
97 return WIMLIB_ERR_NOMEM;
100 /* Read the metadata resource into memory. (It may be compressed.) */
101 ret = read_full_resource_into_buf(metadata_lte, buf);
105 sha1_buffer(buf, metadata_len, hash);
106 if (!hashes_equal(metadata_lte->hash, hash)) {
107 ERROR("Metadata resource is corrupted (invalid SHA-1 message digest)!");
108 ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
112 DEBUG("Finished reading metadata resource into memory.");
114 /* The root directory entry starts after security data, aligned on an
115 * 8-byte boundary within the metadata resource.
117 * The security data starts with a 4-byte integer giving its total
118 * length, so if we round that up to an 8-byte boundary that gives us
119 * the offset of the root dentry.
121 * Here we read the security data into a wim_security_data structure,
122 * which takes case of rouding total_length. If successful, go ahead
123 * and calculate the offset in the metadata resource of the root dentry.
126 ret = read_wim_security_data(buf, metadata_len, &security_data);
130 DEBUG("Reading root dentry");
132 /* Allocate memory for the root dentry and read it into memory */
133 root = MALLOC(sizeof(struct wim_dentry));
135 ret = WIMLIB_ERR_NOMEM;
136 goto out_free_security_data;
139 ret = read_dentry(buf, metadata_len,
140 security_data->total_length, root);
142 if (ret == 0 && root->length == 0) {
143 WARNING("Metadata resource begins with end-of-directory entry "
144 "(treating as empty image)");
152 goto out_free_security_data;
155 if (dentry_has_long_name(root) || dentry_has_short_name(root)) {
156 WARNING("The root directory has a nonempty name (removing it)");
157 FREE(root->file_name);
158 FREE(root->short_name);
159 root->file_name = NULL;
160 root->short_name = NULL;
161 root->file_name_nbytes = 0;
162 root->short_name_nbytes = 0;
165 /* This is the root dentry, so set its parent to itself. */
168 inode_add_dentry(root, root->d_inode);
170 /* Now read the entire directory entry tree into memory. */
171 DEBUG("Reading dentry tree");
172 ret = read_dentry_tree(buf, metadata_len, root);
174 goto out_free_dentry_tree;
176 /* Build hash table that maps hard link group IDs to dentry sets */
177 ret = dentry_tree_fix_inodes(root, &imd->inode_list);
179 goto out_free_dentry_tree;
182 DEBUG("Running miscellaneous verifications on the dentry tree");
183 image_for_each_inode(inode, imd) {
184 ret = verify_inode(inode, security_data);
186 goto out_free_dentry_tree;
188 DEBUG("Done reading image metadata");
190 imd->root_dentry = root;
191 imd->security_data = security_data;
192 INIT_LIST_HEAD(&imd->unhashed_streams);
195 out_free_dentry_tree:
196 free_dentry_tree(root, wim->lookup_table);
197 out_free_security_data:
198 free_wim_security_data(security_data);
205 recalculate_security_data_length(struct wim_security_data *sd)
207 u32 total_length = sizeof(u64) * sd->num_entries + 2 * sizeof(u32);
208 for (u32 i = 0; i < sd->num_entries; i++)
209 total_length += sd->sizes[i];
210 sd->total_length = (total_length + 7) & ~7;
213 /* Like write_wim_resource(), but the resource is specified by a buffer of
214 * uncompressed data rather a lookup table entry; also writes the SHA1 hash of
215 * the buffer to @hash. */
217 write_wim_resource_from_buffer(const void *buf, size_t buf_size,
218 int out_fd, int out_ctype,
219 struct resource_entry *out_res_entry,
220 u8 hash[SHA1_HASH_SIZE])
222 /* Set up a temporary lookup table entry to provide to
223 * write_wim_resource(). */
224 struct wim_lookup_table_entry lte;
226 lte.resource_location = RESOURCE_IN_ATTACHED_BUFFER;
227 lte.attached_buffer = (void*)buf;
228 lte.resource_entry.original_size = buf_size;
229 lte.resource_entry.flags = 0;
231 ret = write_wim_resource(<e, out_fd, out_ctype, out_res_entry, 0);
233 copy_hash(hash, lte.hash);
237 /* Write the metadata resource for the current WIM image. */
239 write_metadata_resource(WIMStruct *w)
245 struct wim_dentry *root;
246 struct wim_lookup_table_entry *lte;
247 u64 metadata_original_size;
248 struct wim_security_data *sd;
249 struct wim_image_metadata *imd;
251 wimlib_assert(w->out_fd != -1);
252 wimlib_assert(w->current_image != WIMLIB_NO_IMAGE);
254 DEBUG("Writing metadata resource for image %d (offset = %"PRIu64")",
255 w->current_image, filedes_offset(w->out_fd));
257 imd = w->image_metadata[w->current_image - 1];
259 root = imd->root_dentry;
260 sd = imd->security_data;
263 /* Empty image; create a dummy root. */
264 ret = new_filler_directory(T(""), &root);
267 imd->root_dentry = root;
270 /* Offset of first child of the root dentry. It's equal to:
271 * - The total length of the security data, rounded to the next 8-byte
273 * - plus the total length of the root dentry,
274 * - plus 8 bytes for an end-of-directory entry following the root
275 * dentry (shouldn't really be needed, but just in case...)
277 recalculate_security_data_length(sd);
278 subdir_offset = (((u64)sd->total_length + 7) & ~7) +
279 dentry_correct_total_length(root) + 8;
281 /* Calculate the subdirectory offsets for the entire dentry tree. */
282 calculate_subdir_offsets(root, &subdir_offset);
284 /* Total length of the metadata resource (uncompressed) */
285 metadata_original_size = subdir_offset;
287 /* Allocate a buffer to contain the uncompressed metadata resource */
288 buf = MALLOC(metadata_original_size);
290 ERROR("Failed to allocate %"PRIu64" bytes for "
291 "metadata resource", metadata_original_size);
292 return WIMLIB_ERR_NOMEM;
295 /* Write the security data into the resource buffer */
296 p = write_wim_security_data(sd, buf);
298 /* Write the dentry tree into the resource buffer */
299 p = write_dentry_tree(root, p);
301 /* We MUST have exactly filled the buffer; otherwise we calculated its
302 * size incorrectly or wrote the data incorrectly. */
303 wimlib_assert(p - buf == metadata_original_size);
305 /* Get the lookup table entry for the metadata resource so we can update
307 lte = wim_get_current_image_metadata(w)->metadata_lte;
309 /* Write the metadata resource to the output WIM using the proper
310 * compression type. The lookup table entry for the metadata resource
312 ret = write_wim_resource_from_buffer(buf, metadata_original_size,
315 <e->output_resource_entry,
317 /* Note that although the SHA1 message digest of the metadata resource
318 * is very likely to have changed, the corresponding lookup table entry
319 * is not actually located in the hash table, so it need not be
320 * re-inserted in the hash table. */
322 /* All the data has been written to the new WIM; no need for the buffer