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/.
23 #include "wimlib_internal.h"
25 #include "lookup_table.h"
28 * Reads a metadata resource for an image in the WIM file. The metadata
29 * resource consists of the security data, followed by the directory entry for
30 * the root directory, followed by all the other directory entries in the
31 * filesystem. The subdir_offset field of each directory entry gives the start
32 * of its child entries from the beginning of the metadata resource. An
33 * end-of-directory is signaled by a directory entry of length '0', really of
34 * length 8, because that's how long the 'length' field is.
36 * @w: Pointer to the WIMStruct for the WIM file.
38 * @imd: Pointer to the image metadata structure for the image whose
39 * metadata resource we are reading. Its `metadata_lte' member
40 * specifies the lookup table entry for the metadata resource. The
41 * rest of the image metadata entry will be filled in by this
44 * Returns: Zero on success, nonzero on failure.
47 read_metadata_resource(WIMStruct *w, struct wim_image_metadata *imd)
52 struct wim_dentry *dentry;
53 const struct wim_lookup_table_entry *metadata_lte;
56 metadata_lte = imd->metadata_lte;
57 metadata_len = wim_resource_size(metadata_lte);
59 DEBUG("Reading metadata resource: original_size = %"PRIu64", "
60 "size = %"PRIu64", offset = %"PRIu64"",
61 metadata_lte->resource_entry.original_size,
62 metadata_lte->resource_entry.size,
63 metadata_lte->resource_entry.offset);
65 /* There is no way the metadata resource could possibly be less than (8
66 * + WIM_DENTRY_DISK_SIZE) bytes, where the 8 is for security data (with
67 * no security descriptors) and WIM_DENTRY_DISK_SIZE is for the root
69 if (metadata_len < 8 + WIM_DENTRY_DISK_SIZE) {
70 ERROR("Expected at least %u bytes for the metadata resource",
71 8 + WIM_DENTRY_DISK_SIZE);
72 return WIMLIB_ERR_INVALID_RESOURCE_SIZE;
75 if (sizeof(size_t) < 8 && metadata_len > 0xffffffff) {
76 ERROR("Metadata resource is too large (%"PRIu64" bytes",
78 return WIMLIB_ERR_INVALID_RESOURCE_SIZE;
81 /* Allocate memory for the uncompressed metadata resource. */
82 buf = MALLOC(metadata_len);
85 ERROR("Failed to allocate %"PRIu64" bytes for uncompressed "
86 "metadata resource", metadata_len);
87 return WIMLIB_ERR_NOMEM;
90 /* Read the metadata resource into memory. (It may be compressed.) */
91 ret = read_full_resource_into_buf(metadata_lte, buf);
95 DEBUG("Finished reading metadata resource into memory.");
97 /* The root directory entry starts after security data, aligned on an
98 * 8-byte boundary within the metadata resource.
100 * The security data starts with a 4-byte integer giving its total
101 * length, so if we round that up to an 8-byte boundary that gives us
102 * the offset of the root dentry.
104 * Here we read the security data into a wim_security_data structure,
105 * and if successful, go ahead and calculate the offset in the metadata
106 * resource of the root dentry. */
108 wimlib_assert(imd->security_data == NULL);
109 ret = read_security_data(buf, metadata_len, &imd->security_data);
113 dentry_offset = (imd->security_data->total_length + 7) & ~7;
115 if (dentry_offset == 0) {
116 ERROR("Integer overflow while reading metadata resource");
117 ret = WIMLIB_ERR_INVALID_SECURITY_DATA;
118 goto out_free_security_data;
121 DEBUG("Reading root dentry");
123 /* Allocate memory for the root dentry and read it into memory */
124 dentry = MALLOC(sizeof(struct wim_dentry));
126 ERROR("Failed to allocate %zu bytes for root dentry",
127 sizeof(struct wim_dentry));
128 ret = WIMLIB_ERR_NOMEM;
129 goto out_free_security_data;
132 ret = read_dentry(buf, metadata_len, dentry_offset, dentry);
134 /* This is the root dentry, so set its parent to itself. */
135 dentry->parent = dentry;
137 if (ret == 0 && dentry->length == 0) {
138 ERROR("Metadata resource cannot begin with end-of-directory entry!");
139 ret = WIMLIB_ERR_INVALID_DENTRY;
144 goto out_free_security_data;
147 inode_add_dentry(dentry, dentry->d_inode);
149 /* Now read the entire directory entry tree into memory. */
150 DEBUG("Reading dentry tree");
151 ret = read_dentry_tree(buf, metadata_len, dentry);
153 goto out_free_dentry_tree;
155 /* Build hash table that maps hard link group IDs to dentry sets */
156 ret = dentry_tree_fix_inodes(dentry, &imd->inode_list);
158 goto out_free_dentry_tree;
160 if (!w->all_images_verified) {
161 DEBUG("Running miscellaneous verifications on the dentry tree");
162 for_lookup_table_entry(w->lookup_table, lte_zero_real_refcnt, NULL);
163 ret = for_dentry_in_tree(dentry, verify_dentry, w);
165 goto out_free_dentry_tree;
168 DEBUG("Done reading image metadata");
170 imd->root_dentry = dentry;
171 INIT_LIST_HEAD(&imd->unhashed_streams);
173 out_free_dentry_tree:
174 free_dentry_tree(dentry, NULL);
175 out_free_security_data:
176 free_security_data(imd->security_data);
177 imd->security_data = NULL;
184 recalculate_security_data_length(struct wim_security_data *sd)
186 u32 total_length = sizeof(u64) * sd->num_entries + 2 * sizeof(u32);
187 for (u32 i = 0; i < sd->num_entries; i++)
188 total_length += sd->sizes[i];
189 sd->total_length = total_length;
192 /* Like write_wim_resource(), but the resource is specified by a buffer of
193 * uncompressed data rather a lookup table entry; also writes the SHA1 hash of
194 * the buffer to @hash. */
196 write_wim_resource_from_buffer(const void *buf, size_t buf_size,
197 filedes_t out_fd, int out_ctype,
198 struct resource_entry *out_res_entry,
199 u8 hash[SHA1_HASH_SIZE])
201 /* Set up a temporary lookup table entry to provide to
202 * write_wim_resource(). */
203 struct wim_lookup_table_entry lte;
205 lte.resource_location = RESOURCE_IN_ATTACHED_BUFFER;
206 lte.attached_buffer = (void*)buf;
207 lte.resource_entry.original_size = buf_size;
208 lte.resource_entry.flags = 0;
210 ret = write_wim_resource(<e, out_fd, out_ctype, out_res_entry, 0);
212 copy_hash(hash, lte.hash);
216 /* Write the metadata resource for the current WIM image. */
218 write_metadata_resource(WIMStruct *w)
224 struct wim_dentry *root;
225 struct wim_lookup_table_entry *lte;
226 u64 metadata_original_size;
227 struct wim_security_data *sd;
229 wimlib_assert(w->out_fd != INVALID_FILEDES);
230 wimlib_assert(w->current_image != WIMLIB_NO_IMAGE);
232 DEBUG("Writing metadata resource for image %d (offset = %"PRIu64")",
233 w->current_image, filedes_offset(w->out_fd));
236 root = wim_root_dentry(w);
237 sd = wim_security_data(w);
239 /* Offset of first child of the root dentry. It's equal to:
240 * - The total length of the security data, rounded to the next 8-byte
242 * - plus the total length of the root dentry,
243 * - plus 8 bytes for an end-of-directory entry following the root
244 * dentry (shouldn't really be needed, but just in case...)
246 recalculate_security_data_length(sd);
247 subdir_offset = (((u64)sd->total_length + 7) & ~7) +
248 dentry_correct_total_length(root) + 8;
250 /* Calculate the subdirectory offsets for the entire dentry tree. */
251 calculate_subdir_offsets(root, &subdir_offset);
253 /* Total length of the metadata resource (uncompressed) */
254 metadata_original_size = subdir_offset;
256 /* Allocate a buffer to contain the uncompressed metadata resource */
257 buf = MALLOC(metadata_original_size);
259 ERROR("Failed to allocate %"PRIu64" bytes for "
260 "metadata resource", metadata_original_size);
261 return WIMLIB_ERR_NOMEM;
264 /* Write the security data into the resource buffer */
265 p = write_security_data(sd, buf);
267 /* Write the dentry tree into the resource buffer */
268 p = write_dentry_tree(root, p);
270 /* We MUST have exactly filled the buffer; otherwise we calculated its
271 * size incorrectly or wrote the data incorrectly. */
272 wimlib_assert(p - buf == metadata_original_size);
274 /* Get the lookup table entry for the metadata resource so we can update
276 lte = wim_get_current_image_metadata(w)->metadata_lte;
278 /* Write the metadata resource to the output WIM using the proper
279 * compression type. The lookup table entry for the metadata resource
281 ret = write_wim_resource_from_buffer(buf, metadata_original_size,
283 wimlib_get_compression_type(w),
284 <e->output_resource_entry,
286 /* Note that although the SHA1 message digest of the metadata resource
287 * is very likely to have changed, the corresponding lookup table entry
288 * is not actually located in the hash table, so it need not be
289 * re-inserted in the hash table. */
291 /* All the data has been written to the new WIM; no need for the buffer