1 /*
2 * template.c
3 *
4 * API to reference a template image to optimize later writing of a WIM file.
5 */
6
7 /*
8 * Copyright (C) 2013, 2015 Eric Biggers
9 *
10 * This file is free software; you can redistribute it and/or modify it under
11 * the terms of the GNU Lesser General Public License as published by the Free
12 * Software Foundation; either version 3 of the License, or (at your option) any
13 * later version.
14 *
15 * This file is distributed in the hope that it will be useful, but WITHOUT
16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
17 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
18 * details.
19 *
20 * You should have received a copy of the GNU Lesser General Public License
21 * along with this file; if not, see http://www.gnu.org/licenses/.
22 */
23
24 #ifdef HAVE_CONFIG_H
25 # include "config.h"
26 #endif
27
28 #include "wimlib.h"
29 #include "wimlib/blob_table.h"
30 #include "wimlib/assert.h"
31 #include "wimlib/dentry.h"
32 #include "wimlib/error.h"
33 #include "wimlib/metadata.h"
34 #include "wimlib/util.h"
35
36 static u64
stream_size(const struct wim_inode_stream * strm,const struct blob_table * blob_table)37 stream_size(const struct wim_inode_stream *strm,
38 const struct blob_table *blob_table)
39 {
40 const struct blob_descriptor *blob;
41
42 blob = stream_blob(strm, blob_table);
43 if (!blob)
44 return 0;
45 return blob->size;
46 }
47
48 /* Returns %true iff the metadata of @inode and @template_inode are reasonably
49 * consistent with them being the same, unmodified file. */
50 static bool
inode_metadata_consistent(const struct wim_inode * inode,const struct wim_inode * template_inode,const struct blob_table * blob_table,const struct blob_table * template_blob_table)51 inode_metadata_consistent(const struct wim_inode *inode,
52 const struct wim_inode *template_inode,
53 const struct blob_table *blob_table,
54 const struct blob_table *template_blob_table)
55 {
56 /* Must have exact same creation time and last write time. */
57 if (inode->i_creation_time != template_inode->i_creation_time ||
58 inode->i_last_write_time != template_inode->i_last_write_time)
59 return false;
60
61 /* Last access time may have stayed the same or increased, but certainly
62 * shouldn't have decreased. */
63 if (inode->i_last_access_time < template_inode->i_last_access_time)
64 return false;
65
66 /* All stream sizes must match. */
67 for (unsigned i = 0; i < inode->i_num_streams; i++) {
68 const struct wim_inode_stream *strm, *template_strm;
69
70 strm = &inode->i_streams[i];
71 template_strm = inode_get_stream(template_inode,
72 strm->stream_type,
73 strm->stream_name);
74 if (!template_strm)
75 return false;
76
77 if (stream_size(strm, blob_table) !=
78 stream_size(template_strm, template_blob_table))
79 return false;
80 }
81
82 return true;
83 }
84
85 /**
86 * Given an inode @inode that has been determined to be "the same" as another
87 * inode @template_inode in either the same WIM or another WIM, copy stream
88 * checksums from @template_inode to @inode.
89 */
90 static void
inode_copy_checksums(struct wim_inode * inode,struct wim_inode * template_inode,struct blob_table * blob_table,struct blob_table * template_blob_table)91 inode_copy_checksums(struct wim_inode *inode,
92 struct wim_inode *template_inode,
93 struct blob_table *blob_table,
94 struct blob_table *template_blob_table)
95 {
96 for (unsigned i = 0; i < inode->i_num_streams; i++) {
97 const struct wim_inode_stream *strm, *template_strm;
98 struct blob_descriptor *blob, *template_blob, **back_ptr;
99
100 strm = &inode->i_streams[i];
101 template_strm = inode_get_stream(template_inode,
102 strm->stream_type,
103 strm->stream_name);
104
105 blob = stream_blob(strm, blob_table);
106 template_blob = stream_blob(template_strm, template_blob_table);
107
108 /* To copy hashes: both blobs must exist, the blob for @inode
109 * must be unhashed, and the blob for @template_inode must be
110 * hashed. */
111 if (!blob || !template_blob ||
112 !blob->unhashed || template_blob->unhashed)
113 continue;
114
115 back_ptr = retrieve_pointer_to_unhashed_blob(blob);
116 copy_hash(blob->hash, template_blob->hash);
117 if (after_blob_hashed(blob, back_ptr, blob_table) != blob)
118 free_blob_descriptor(blob);
119 }
120 }
121
122 static int
reference_template_file(struct wim_inode * inode,WIMStruct * wim,WIMStruct * template_wim)123 reference_template_file(struct wim_inode *inode, WIMStruct *wim,
124 WIMStruct *template_wim)
125 {
126 struct wim_dentry *dentry = inode_any_dentry(inode);
127 struct wim_dentry *template_dentry;
128 int ret;
129
130 ret = calculate_dentry_full_path(dentry);
131 if (ret)
132 return ret;
133
134 template_dentry = get_dentry(template_wim, dentry->d_full_path,
135 WIMLIB_CASE_SENSITIVE);
136 if (template_dentry != NULL &&
137 inode_metadata_consistent(inode, template_dentry->d_inode,
138 wim->blob_table, template_wim->blob_table))
139 {
140 inode_copy_checksums(inode, template_dentry->d_inode,
141 wim->blob_table, template_wim->blob_table);
142 }
143
144 FREE(dentry->d_full_path);
145 dentry->d_full_path = NULL;
146 return 0;
147 }
148
149 /* API function documented in wimlib.h */
150 WIMLIBAPI int
wimlib_reference_template_image(WIMStruct * wim,int new_image,WIMStruct * template_wim,int template_image,int flags)151 wimlib_reference_template_image(WIMStruct *wim, int new_image,
152 WIMStruct *template_wim, int template_image,
153 int flags)
154 {
155 int ret;
156 struct wim_image_metadata *new_imd;
157 struct wim_inode *inode;
158
159 if (flags != 0)
160 return WIMLIB_ERR_INVALID_PARAM;
161
162 if (wim == NULL || template_wim == NULL)
163 return WIMLIB_ERR_INVALID_PARAM;
164
165 if (wim == template_wim && new_image == template_image)
166 return WIMLIB_ERR_INVALID_PARAM;
167
168 if (new_image < 1 || new_image > wim->hdr.image_count)
169 return WIMLIB_ERR_INVALID_IMAGE;
170
171 if (!wim_has_metadata(wim))
172 return WIMLIB_ERR_METADATA_NOT_FOUND;
173
174 new_imd = wim->image_metadata[new_image - 1];
175 if (!is_image_dirty(new_imd))
176 return WIMLIB_ERR_INVALID_PARAM;
177
178 ret = select_wim_image(template_wim, template_image);
179 if (ret)
180 return ret;
181
182 image_for_each_inode(inode, new_imd) {
183 ret = reference_template_file(inode, wim, template_wim);
184 if (ret)
185 return ret;
186 }
187
188 return 0;
189 }
190