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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
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
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 */
119 static int qcow2_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 bdrv_flush(bs->file);
142 offset = snapshots_offset;
143 if (offset < 0) {
144 return offset;
145 }
146
147 for(i = 0; i < s->nb_snapshots; i++) {
148 sn = s->snapshots + i;
149 memset(&h, 0, sizeof(h));
150 h.l1_table_offset = cpu_to_be64(sn->l1_table_offset);
151 h.l1_size = cpu_to_be32(sn->l1_size);
152 h.vm_state_size = cpu_to_be32(sn->vm_state_size);
153 h.date_sec = cpu_to_be32(sn->date_sec);
154 h.date_nsec = cpu_to_be32(sn->date_nsec);
155 h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec);
156
157 id_str_size = strlen(sn->id_str);
158 name_size = strlen(sn->name);
159 h.id_str_size = cpu_to_be16(id_str_size);
160 h.name_size = cpu_to_be16(name_size);
161 offset = align_offset(offset, 8);
162 if (bdrv_pwrite_sync(bs->file, offset, &h, sizeof(h)) < 0)
163 goto fail;
164 offset += sizeof(h);
165 if (bdrv_pwrite_sync(bs->file, offset, sn->id_str, id_str_size) < 0)
166 goto fail;
167 offset += id_str_size;
168 if (bdrv_pwrite_sync(bs->file, offset, sn->name, name_size) < 0)
169 goto fail;
170 offset += name_size;
171 }
172
173 /* update the various header fields */
174 data64 = cpu_to_be64(snapshots_offset);
175 if (bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, snapshots_offset),
176 &data64, sizeof(data64)) < 0)
177 goto fail;
178 data32 = cpu_to_be32(s->nb_snapshots);
179 if (bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots),
180 &data32, sizeof(data32)) < 0)
181 goto fail;
182
183 /* free the old snapshot table */
184 qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);
185 s->snapshots_offset = snapshots_offset;
186 s->snapshots_size = snapshots_size;
187 return 0;
188 fail:
189 return -1;
190 }
191
192 static void find_new_snapshot_id(BlockDriverState *bs,
193 char *id_str, int id_str_size)
194 {
195 BDRVQcowState *s = bs->opaque;
196 QCowSnapshot *sn;
197 int i, id, id_max = 0;
198
199 for(i = 0; i < s->nb_snapshots; i++) {
200 sn = s->snapshots + i;
201 id = strtoul(sn->id_str, NULL, 10);
202 if (id > id_max)
203 id_max = id;
204 }
205 snprintf(id_str, id_str_size, "%d", id_max + 1);
206 }
207
208 static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
209 {
210 BDRVQcowState *s = bs->opaque;
211 int i;
212
213 for(i = 0; i < s->nb_snapshots; i++) {
214 if (!strcmp(s->snapshots[i].id_str, id_str))
215 return i;
216 }
217 return -1;
218 }
219
220 static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
221 {
222 BDRVQcowState *s = bs->opaque;
223 int i, ret;
224
225 ret = find_snapshot_by_id(bs, name);
226 if (ret >= 0)
227 return ret;
228 for(i = 0; i < s->nb_snapshots; i++) {
229 if (!strcmp(s->snapshots[i].name, name))
230 return i;
231 }
232 return -1;
233 }
234
235 /* if no id is provided, a new one is constructed */
236 int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
237 {
238 BDRVQcowState *s = bs->opaque;
239 QCowSnapshot *snapshots1, sn1, *sn = &sn1;
240 int i, ret;
241 uint64_t *l1_table = NULL;
242 int64_t l1_table_offset;
243
244 memset(sn, 0, sizeof(*sn));
245
246 if (sn_info->id_str[0] == '\0') {
247 /* compute a new id */
248 find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
249 }
250
251 /* check that the ID is unique */
252 if (find_snapshot_by_id(bs, sn_info->id_str) >= 0)
253 return -ENOENT;
254
255 sn->id_str = qemu_strdup(sn_info->id_str);
256 if (!sn->id_str)
257 goto fail;
258 sn->name = qemu_strdup(sn_info->name);
259 if (!sn->name)
260 goto fail;
261 sn->vm_state_size = sn_info->vm_state_size;
262 sn->date_sec = sn_info->date_sec;
263 sn->date_nsec = sn_info->date_nsec;
264 sn->vm_clock_nsec = sn_info->vm_clock_nsec;
265
266 ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
267 if (ret < 0)
268 goto fail;
269
270 /* create the L1 table of the snapshot */
271 l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
272 if (l1_table_offset < 0) {
273 goto fail;
274 }
275 bdrv_flush(bs->file);
276
277 sn->l1_table_offset = l1_table_offset;
278 sn->l1_size = s->l1_size;
279
280 if (s->l1_size != 0) {
281 l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
282 } else {
283 l1_table = NULL;
284 }
285
286 for(i = 0; i < s->l1_size; i++) {
287 l1_table[i] = cpu_to_be64(s->l1_table[i]);
288 }
289 if (bdrv_pwrite_sync(bs->file, sn->l1_table_offset,
290 l1_table, s->l1_size * sizeof(uint64_t)) < 0)
291 goto fail;
292 qemu_free(l1_table);
293 l1_table = NULL;
294
295 snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
296 if (s->snapshots) {
297 memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
298 qemu_free(s->snapshots);
299 }
300 s->snapshots = snapshots1;
301 s->snapshots[s->nb_snapshots++] = *sn;
302
303 if (qcow2_write_snapshots(bs) < 0)
304 goto fail;
305 #ifdef DEBUG_ALLOC
306 qcow2_check_refcounts(bs);
307 #endif
308 return 0;
309 fail:
310 qemu_free(sn->name);
311 qemu_free(l1_table);
312 return -1;
313 }
314
315 /* copy the snapshot 'snapshot_name' into the current disk image */
316 int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
317 {
318 BDRVQcowState *s = bs->opaque;
319 QCowSnapshot *sn;
320 int i, snapshot_index, l1_size2;
321
322 snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
323 if (snapshot_index < 0)
324 return -ENOENT;
325 sn = &s->snapshots[snapshot_index];
326
327 if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0)
328 goto fail;
329
330 if (qcow2_grow_l1_table(bs, sn->l1_size, true) < 0)
331 goto fail;
332
333 s->l1_size = sn->l1_size;
334 l1_size2 = s->l1_size * sizeof(uint64_t);
335 /* copy the snapshot l1 table to the current l1 table */
336 if (bdrv_pread(bs->file, sn->l1_table_offset,
337 s->l1_table, l1_size2) != l1_size2)
338 goto fail;
339 if (bdrv_pwrite_sync(bs->file, s->l1_table_offset,
340 s->l1_table, l1_size2) < 0)
341 goto fail;
342 for(i = 0;i < s->l1_size; i++) {
343 be64_to_cpus(&s->l1_table[i]);
344 }
345
346 if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0)
347 goto fail;
348
349 #ifdef DEBUG_ALLOC
350 qcow2_check_refcounts(bs);
351 #endif
352 return 0;
353 fail:
354 return -EIO;
355 }
356
357 int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
358 {
359 BDRVQcowState *s = bs->opaque;
360 QCowSnapshot *sn;
361 int snapshot_index, ret;
362
363 snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
364 if (snapshot_index < 0)
365 return -ENOENT;
366 sn = &s->snapshots[snapshot_index];
367
368 ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1);
369 if (ret < 0)
370 return ret;
371 /* must update the copied flag on the current cluster offsets */
372 ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
373 if (ret < 0)
374 return ret;
375 qcow2_free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t));
376
377 qemu_free(sn->id_str);
378 qemu_free(sn->name);
379 memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn));
380 s->nb_snapshots--;
381 ret = qcow2_write_snapshots(bs);
382 if (ret < 0) {
383 /* XXX: restore snapshot if error ? */
384 return ret;
385 }
386 #ifdef DEBUG_ALLOC
387 qcow2_check_refcounts(bs);
388 #endif
389 return 0;
390 }
391
392 int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
393 {
394 BDRVQcowState *s = bs->opaque;
395 QEMUSnapshotInfo *sn_tab, *sn_info;
396 QCowSnapshot *sn;
397 int i;
398
399 if (!s->nb_snapshots) {
400 *psn_tab = NULL;
401 return s->nb_snapshots;
402 }
403
404 sn_tab = qemu_mallocz(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
405 for(i = 0; i < s->nb_snapshots; i++) {
406 sn_info = sn_tab + i;
407 sn = s->snapshots + i;
408 pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
409 sn->id_str);
410 pstrcpy(sn_info->name, sizeof(sn_info->name),
411 sn->name);
412 sn_info->vm_state_size = sn->vm_state_size;
413 sn_info->date_sec = sn->date_sec;
414 sn_info->date_nsec = sn->date_nsec;
415 sn_info->vm_clock_nsec = sn->vm_clock_nsec;
416 }
417 *psn_tab = sn_tab;
418 return s->nb_snapshots;
419 }
420
421 int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name)
422 {
423 int i, snapshot_index, l1_size2;
424 BDRVQcowState *s = bs->opaque;
425 QCowSnapshot *sn;
426
427 snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_name);
428 if (snapshot_index < 0) {
429 return -ENOENT;
430 }
431
432 sn = &s->snapshots[snapshot_index];
433 s->l1_size = sn->l1_size;
434 l1_size2 = s->l1_size * sizeof(uint64_t);
435 if (s->l1_table != NULL) {
436 qemu_free(s->l1_table);
437 }
438
439 s->l1_table_offset = sn->l1_table_offset;
440 s->l1_table = qemu_mallocz(align_offset(l1_size2, 512));
441
442 if (bdrv_pread(bs->file, sn->l1_table_offset,
443 s->l1_table, l1_size2) != l1_size2) {
444 return -1;
445 }
446
447 for(i = 0;i < s->l1_size; i++) {
448 be64_to_cpus(&s->l1_table[i]);
449 }
450 return 0;
451 }