1 /*
2 * Block driver for the QCOW version 2 format
3 *
4 * Copyright (c) 2004-2006 Fabrice Bellard
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25 #include "qemu-common.h"
26 #include "block_int.h"
27 #include "block/qcow2.h"
28
29 typedef struct __attribute__((packed)) QCowSnapshotHeader {
30 /* header is 8 byte aligned */
31 uint64_t l1_table_offset;
32
33 uint32_t l1_size;
34 uint16_t id_str_size;
35 uint16_t name_size;
36
37 uint32_t date_sec;
38 uint32_t date_nsec;
39
40 uint64_t vm_clock_nsec;
41
42 uint32_t vm_state_size;
43 uint32_t extra_data_size; /* for extension */
44 /* extra data follows */
45 /* id_str follows */
46 /* name follows */
47 } QCowSnapshotHeader;
48
qcow2_free_snapshots(BlockDriverState * bs)49 void qcow2_free_snapshots(BlockDriverState *bs)
50 {
51 BDRVQcowState *s = bs->opaque;
52 int i;
53
54 for(i = 0; i < s->nb_snapshots; i++) {
55 qemu_free(s->snapshots[i].name);
56 qemu_free(s->snapshots[i].id_str);
57 }
58 qemu_free(s->snapshots);
59 s->snapshots = NULL;
60 s->nb_snapshots = 0;
61 }
62
qcow2_read_snapshots(BlockDriverState * bs)63 int qcow2_read_snapshots(BlockDriverState *bs)
64 {
65 BDRVQcowState *s = bs->opaque;
66 QCowSnapshotHeader h;
67 QCowSnapshot *sn;
68 int i, id_str_size, name_size;
69 int64_t offset;
70 uint32_t extra_data_size;
71
72 if (!s->nb_snapshots) {
73 s->snapshots = NULL;
74 s->snapshots_size = 0;
75 return 0;
76 }
77
78 offset = s->snapshots_offset;
79 s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot));
80 for(i = 0; i < s->nb_snapshots; i++) {
81 offset = align_offset(offset, 8);
82 if (bdrv_pread(bs->file, offset, &h, sizeof(h)) != sizeof(h))
83 goto fail;
84 offset += sizeof(h);
85 sn = s->snapshots + i;
86 sn->l1_table_offset = be64_to_cpu(h.l1_table_offset);
87 sn->l1_size = be32_to_cpu(h.l1_size);
88 sn->vm_state_size = be32_to_cpu(h.vm_state_size);
89 sn->date_sec = be32_to_cpu(h.date_sec);
90 sn->date_nsec = be32_to_cpu(h.date_nsec);
91 sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec);
92 extra_data_size = be32_to_cpu(h.extra_data_size);
93
94 id_str_size = be16_to_cpu(h.id_str_size);
95 name_size = be16_to_cpu(h.name_size);
96
97 offset += extra_data_size;
98
99 sn->id_str = qemu_malloc(id_str_size + 1);
100 if (bdrv_pread(bs->file, offset, sn->id_str, id_str_size) != id_str_size)
101 goto fail;
102 offset += id_str_size;
103 sn->id_str[id_str_size] = '\0';
104
105 sn->name = qemu_malloc(name_size + 1);
106 if (bdrv_pread(bs->file, offset, sn->name, name_size) != name_size)
107 goto fail;
108 offset += name_size;
109 sn->name[name_size] = '\0';
110 }
111 s->snapshots_size = offset - s->snapshots_offset;
112 return 0;
113 fail:
114 qcow2_free_snapshots(bs);
115 return -1;
116 }
117
118 /* add at the end of the file a new list of snapshots */
qcow_write_snapshots(BlockDriverState * bs)119 static int qcow_write_snapshots(BlockDriverState *bs)
120 {
121 BDRVQcowState *s = bs->opaque;
122 QCowSnapshot *sn;
123 QCowSnapshotHeader h;
124 int i, name_size, id_str_size, snapshots_size;
125 uint64_t data64;
126 uint32_t data32;
127 int64_t offset, snapshots_offset;
128
129 /* compute the size of the snapshots */
130 offset = 0;
131 for(i = 0; i < s->nb_snapshots; i++) {
132 sn = s->snapshots + i;
133 offset = align_offset(offset, 8);
134 offset += sizeof(h);
135 offset += strlen(sn->id_str);
136 offset += strlen(sn->name);
137 }
138 snapshots_size = offset;
139
140 snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size);
141 offset = snapshots_offset;
142 if (offset < 0) {
143 return offset;
144 }
145
146 for(i = 0; i < s->nb_snapshots; i++) {
147 sn = s->snapshots + i;
148 memset(&h, 0, sizeof(h));
149 h.l1_table_offset = cpu_to_be64(sn->l1_table_offset);
150 h.l1_size = cpu_to_be32(sn->l1_size);
151 h.vm_state_size = cpu_to_be32(sn->vm_state_size);
152 h.date_sec = cpu_to_be32(sn->date_sec);
153 h.date_nsec = cpu_to_be32(sn->date_nsec);
154 h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec);
155
156 id_str_size = strlen(sn->id_str);
157 name_size = strlen(sn->name);
158 h.id_str_size = cpu_to_be16(id_str_size);
159 h.name_size = cpu_to_be16(name_size);
160 offset = align_offset(offset, 8);
161 if (bdrv_pwrite_sync(bs->file, offset, &h, sizeof(h)) < 0)
162 goto fail;
163 offset += sizeof(h);
164 if (bdrv_pwrite_sync(bs->file, offset, sn->id_str, id_str_size) < 0)
165 goto fail;
166 offset += id_str_size;
167 if (bdrv_pwrite_sync(bs->file, offset, sn->name, name_size) < 0)
168 goto fail;
169 offset += name_size;
170 }
171
172 /* update the various header fields */
173 data64 = cpu_to_be64(snapshots_offset);
174 if (bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, snapshots_offset),
175 &data64, sizeof(data64)) < 0)
176 goto fail;
177 data32 = cpu_to_be32(s->nb_snapshots);
178 if (bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots),
179 &data32, sizeof(data32)) < 0)
180 goto fail;
181
182 /* free the old snapshot table */
183 qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);
184 s->snapshots_offset = snapshots_offset;
185 s->snapshots_size = snapshots_size;
186 return 0;
187 fail:
188 return -1;
189 }
190
find_new_snapshot_id(BlockDriverState * bs,char * id_str,int id_str_size)191 static void find_new_snapshot_id(BlockDriverState *bs,
192 char *id_str, int id_str_size)
193 {
194 BDRVQcowState *s = bs->opaque;
195 QCowSnapshot *sn;
196 int i, id, id_max = 0;
197
198 for(i = 0; i < s->nb_snapshots; i++) {
199 sn = s->snapshots + i;
200 id = strtoul(sn->id_str, NULL, 10);
201 if (id > id_max)
202 id_max = id;
203 }
204 snprintf(id_str, id_str_size, "%d", id_max + 1);
205 }
206
find_snapshot_by_id(BlockDriverState * bs,const char * id_str)207 static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
208 {
209 BDRVQcowState *s = bs->opaque;
210 int i;
211
212 for(i = 0; i < s->nb_snapshots; i++) {
213 if (!strcmp(s->snapshots[i].id_str, id_str))
214 return i;
215 }
216 return -1;
217 }
218
find_snapshot_by_id_or_name(BlockDriverState * bs,const char * name)219 static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
220 {
221 BDRVQcowState *s = bs->opaque;
222 int i, ret;
223
224 ret = find_snapshot_by_id(bs, name);
225 if (ret >= 0)
226 return ret;
227 for(i = 0; i < s->nb_snapshots; i++) {
228 if (!strcmp(s->snapshots[i].name, name))
229 return i;
230 }
231 return -1;
232 }
233
234 /* if no id is provided, a new one is constructed */
qcow2_snapshot_create(BlockDriverState * bs,QEMUSnapshotInfo * sn_info)235 int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
236 {
237 BDRVQcowState *s = bs->opaque;
238 QCowSnapshot *snapshots1, sn1, *sn = &sn1;
239 int i, ret;
240 uint64_t *l1_table = NULL;
241 int64_t l1_table_offset;
242
243 memset(sn, 0, sizeof(*sn));
244
245 if (sn_info->id_str[0] == '\0') {
246 /* compute a new id */
247 find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
248 }
249
250 /* check that the ID is unique */
251 if (find_snapshot_by_id(bs, sn_info->id_str) >= 0)
252 return -ENOENT;
253
254 sn->id_str = qemu_strdup(sn_info->id_str);
255 if (!sn->id_str)
256 goto fail;
257 sn->name = qemu_strdup(sn_info->name);
258 if (!sn->name)
259 goto fail;
260 sn->vm_state_size = sn_info->vm_state_size;
261 sn->date_sec = sn_info->date_sec;
262 sn->date_nsec = sn_info->date_nsec;
263 sn->vm_clock_nsec = sn_info->vm_clock_nsec;
264
265 ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
266 if (ret < 0)
267 goto fail;
268
269 /* create the L1 table of the snapshot */
270 l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
271 if (l1_table_offset < 0) {
272 goto fail;
273 }
274
275 sn->l1_table_offset = l1_table_offset;
276 sn->l1_size = s->l1_size;
277
278 if (s->l1_size != 0) {
279 l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
280 } else {
281 l1_table = NULL;
282 }
283
284 for(i = 0; i < s->l1_size; i++) {
285 l1_table[i] = cpu_to_be64(s->l1_table[i]);
286 }
287 if (bdrv_pwrite_sync(bs->file, sn->l1_table_offset,
288 l1_table, s->l1_size * sizeof(uint64_t)) < 0)
289 goto fail;
290 qemu_free(l1_table);
291 l1_table = NULL;
292
293 snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
294 if (s->snapshots) {
295 memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
296 qemu_free(s->snapshots);
297 }
298 s->snapshots = snapshots1;
299 s->snapshots[s->nb_snapshots++] = *sn;
300
301 if (qcow_write_snapshots(bs) < 0)
302 goto fail;
303 #ifdef DEBUG_ALLOC
304 qcow2_check_refcounts(bs);
305 #endif
306 return 0;
307 fail:
308 qemu_free(sn->name);
309 qemu_free(l1_table);
310 return -1;
311 }
312
313 /* copy the snapshot 'snapshot_name' into the current disk image */
qcow2_snapshot_goto(BlockDriverState * bs,const char * snapshot_id)314 int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
315 {
316 BDRVQcowState *s = bs->opaque;
317 QCowSnapshot *sn;
318 int i, snapshot_index, l1_size2;
319
320 snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
321 if (snapshot_index < 0)
322 return -ENOENT;
323 sn = &s->snapshots[snapshot_index];
324
325 if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0)
326 goto fail;
327
328 if (qcow2_grow_l1_table(bs, sn->l1_size) < 0)
329 goto fail;
330
331 s->l1_size = sn->l1_size;
332 l1_size2 = s->l1_size * sizeof(uint64_t);
333 /* copy the snapshot l1 table to the current l1 table */
334 if (bdrv_pread(bs->file, sn->l1_table_offset,
335 s->l1_table, l1_size2) != l1_size2)
336 goto fail;
337 if (bdrv_pwrite_sync(bs->file, s->l1_table_offset,
338 s->l1_table, l1_size2) < 0)
339 goto fail;
340 for(i = 0;i < s->l1_size; i++) {
341 be64_to_cpus(&s->l1_table[i]);
342 }
343
344 if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0)
345 goto fail;
346
347 #ifdef DEBUG_ALLOC
348 qcow2_check_refcounts(bs);
349 #endif
350 return 0;
351 fail:
352 return -EIO;
353 }
354
qcow2_snapshot_delete(BlockDriverState * bs,const char * snapshot_id)355 int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
356 {
357 BDRVQcowState *s = bs->opaque;
358 QCowSnapshot *sn;
359 int snapshot_index, ret;
360
361 snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
362 if (snapshot_index < 0)
363 return -ENOENT;
364 sn = &s->snapshots[snapshot_index];
365
366 ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1);
367 if (ret < 0)
368 return ret;
369 /* must update the copied flag on the current cluster offsets */
370 ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
371 if (ret < 0)
372 return ret;
373 qcow2_free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t));
374
375 qemu_free(sn->id_str);
376 qemu_free(sn->name);
377 memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn));
378 s->nb_snapshots--;
379 ret = qcow_write_snapshots(bs);
380 if (ret < 0) {
381 /* XXX: restore snapshot if error ? */
382 return ret;
383 }
384 #ifdef DEBUG_ALLOC
385 qcow2_check_refcounts(bs);
386 #endif
387 return 0;
388 }
389
qcow2_snapshot_list(BlockDriverState * bs,QEMUSnapshotInfo ** psn_tab)390 int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
391 {
392 BDRVQcowState *s = bs->opaque;
393 QEMUSnapshotInfo *sn_tab, *sn_info;
394 QCowSnapshot *sn;
395 int i;
396
397 if (!s->nb_snapshots) {
398 *psn_tab = NULL;
399 return s->nb_snapshots;
400 }
401
402 sn_tab = qemu_mallocz(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
403 for(i = 0; i < s->nb_snapshots; i++) {
404 sn_info = sn_tab + i;
405 sn = s->snapshots + i;
406 pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
407 sn->id_str);
408 pstrcpy(sn_info->name, sizeof(sn_info->name),
409 sn->name);
410 sn_info->vm_state_size = sn->vm_state_size;
411 sn_info->date_sec = sn->date_sec;
412 sn_info->date_nsec = sn->date_nsec;
413 sn_info->vm_clock_nsec = sn->vm_clock_nsec;
414 }
415 *psn_tab = sn_tab;
416 return s->nb_snapshots;
417 }
418
419