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;
63 metadata_lte = imd->metadata_lte;
64 metadata_len = wim_resource_size(metadata_lte);
66 DEBUG("Reading metadata resource: original_size = %"PRIu64", "
67 "size = %"PRIu64", offset = %"PRIu64"",
68 metadata_lte->resource_entry.original_size,
69 metadata_lte->resource_entry.size,
70 metadata_lte->resource_entry.offset);
72 /* There is no way the metadata resource could possibly be less than (8
73 * + WIM_DENTRY_DISK_SIZE) bytes, where the 8 is for security data (with
74 * no security descriptors) and WIM_DENTRY_DISK_SIZE is for the root
76 if (metadata_len < 8 + WIM_DENTRY_DISK_SIZE) {
77 ERROR("Expected at least %u bytes for the metadata resource",
78 8 + WIM_DENTRY_DISK_SIZE);
79 return WIMLIB_ERR_INVALID_RESOURCE_SIZE;
82 if (sizeof(size_t) < 8 && metadata_len > 0xffffffff) {
83 ERROR("Metadata resource is too large (%"PRIu64" bytes",
85 return WIMLIB_ERR_INVALID_RESOURCE_SIZE;
88 /* Allocate memory for the uncompressed metadata resource. */
89 buf = MALLOC(metadata_len);
92 ERROR("Failed to allocate %"PRIu64" bytes for uncompressed "
93 "metadata resource", metadata_len);
94 return WIMLIB_ERR_NOMEM;
97 /* Read the metadata resource into memory. (It may be compressed.) */
98 ret = read_full_resource_into_buf(metadata_lte, buf);
102 DEBUG("Finished reading metadata resource into memory.");
104 /* The root directory entry starts after security data, aligned on an
105 * 8-byte boundary within the metadata resource.
107 * The security data starts with a 4-byte integer giving its total
108 * length, so if we round that up to an 8-byte boundary that gives us
109 * the offset of the root dentry.
111 * Here we read the security data into a wim_security_data structure,
112 * which takes case of rouding total_length. If successful, go ahead
113 * and calculate the offset in the metadata resource of the root dentry.
116 ret = read_wim_security_data(buf, metadata_len, &imd->security_data);
120 DEBUG("Reading root dentry");
122 /* Allocate memory for the root dentry and read it into memory */
123 root = MALLOC(sizeof(struct wim_dentry));
125 ret = WIMLIB_ERR_NOMEM;
126 goto out_free_security_data;
129 ret = read_dentry(buf, metadata_len,
130 imd->security_data->total_length, root);
132 if (ret == 0 && root->length == 0) {
133 ERROR("Metadata resource cannot begin with end-of-directory entry!");
134 ret = WIMLIB_ERR_INVALID_DENTRY;
139 goto out_free_security_data;
142 /* This is the root dentry, so set its parent to itself. */
145 inode_add_dentry(root, root->d_inode);
147 /* Now read the entire directory entry tree into memory. */
148 DEBUG("Reading dentry tree");
149 ret = read_dentry_tree(buf, metadata_len, root);
151 goto out_free_dentry_tree;
153 /* Build hash table that maps hard link group IDs to dentry sets */
154 ret = dentry_tree_fix_inodes(root, &imd->inode_list);
156 goto out_free_dentry_tree;
158 if (!wim->all_images_verified) {
159 /* Note: verify_dentry() expects to access imd->security_data,
160 * so it needs to be set before here. */
161 DEBUG("Running miscellaneous verifications on the dentry tree");
162 for_lookup_table_entry(wim->lookup_table, lte_zero_real_refcnt, NULL);
163 ret = for_dentry_in_tree(root, verify_dentry, wim);
165 goto out_free_dentry_tree;
168 DEBUG("Done reading image metadata");
170 imd->root_dentry = root;
171 INIT_LIST_HEAD(&imd->unhashed_streams);
173 out_free_dentry_tree:
174 free_dentry_tree(root, wim->lookup_table);
175 out_free_security_data:
176 free_wim_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 + 7) & ~7;
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 int 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;
228 struct wim_image_metadata *imd;
230 wimlib_assert(w->out_fd != -1);
231 wimlib_assert(w->current_image != WIMLIB_NO_IMAGE);
233 DEBUG("Writing metadata resource for image %d (offset = %"PRIu64")",
234 w->current_image, filedes_offset(w->out_fd));
236 imd = w->image_metadata[w->current_image - 1];
238 root = imd->root_dentry;
239 sd = imd->security_data;
242 /* Empty image; create a dummy root. */
243 ret = new_filler_directory(T(""), &root);
246 imd->root_dentry = root;
249 /* Offset of first child of the root dentry. It's equal to:
250 * - The total length of the security data, rounded to the next 8-byte
252 * - plus the total length of the root dentry,
253 * - plus 8 bytes for an end-of-directory entry following the root
254 * dentry (shouldn't really be needed, but just in case...)
256 recalculate_security_data_length(sd);
257 subdir_offset = (((u64)sd->total_length + 7) & ~7) +
258 dentry_correct_total_length(root) + 8;
260 /* Calculate the subdirectory offsets for the entire dentry tree. */
261 calculate_subdir_offsets(root, &subdir_offset);
263 /* Total length of the metadata resource (uncompressed) */
264 metadata_original_size = subdir_offset;
266 /* Allocate a buffer to contain the uncompressed metadata resource */
267 buf = MALLOC(metadata_original_size);
269 ERROR("Failed to allocate %"PRIu64" bytes for "
270 "metadata resource", metadata_original_size);
271 return WIMLIB_ERR_NOMEM;
274 /* Write the security data into the resource buffer */
275 p = write_wim_security_data(sd, buf);
277 /* Write the dentry tree into the resource buffer */
278 p = write_dentry_tree(root, p);
280 /* We MUST have exactly filled the buffer; otherwise we calculated its
281 * size incorrectly or wrote the data incorrectly. */
282 wimlib_assert(p - buf == metadata_original_size);
284 /* Get the lookup table entry for the metadata resource so we can update
286 lte = wim_get_current_image_metadata(w)->metadata_lte;
288 /* Write the metadata resource to the output WIM using the proper
289 * compression type. The lookup table entry for the metadata resource
291 ret = write_wim_resource_from_buffer(buf, metadata_original_size,
293 wimlib_get_compression_type(w),
294 <e->output_resource_entry,
296 /* Note that although the SHA1 message digest of the metadata resource
297 * is very likely to have changed, the corresponding lookup table entry
298 * is not actually located in the hash table, so it need not be
299 * re-inserted in the hash table. */
301 /* All the data has been written to the new WIM; no need for the buffer