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1 /*
2  * Block driver for the QCOW 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 #include "qemu-common.h"
25 #include "block_int.h"
26 #include <zlib.h>
27 #include "aes.h"
28 
29 /**************************************************************/
30 /* QEMU COW block driver with compression and encryption support */
31 
32 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
33 #define QCOW_VERSION 1
34 
35 #define QCOW_CRYPT_NONE 0
36 #define QCOW_CRYPT_AES  1
37 
38 #define QCOW_OFLAG_COMPRESSED (1LL << 63)
39 
40 typedef struct QCowHeader {
41     uint32_t magic;
42     uint32_t version;
43     uint64_t backing_file_offset;
44     uint32_t backing_file_size;
45     uint32_t mtime;
46     uint64_t size; /* in bytes */
47     uint8_t cluster_bits;
48     uint8_t l2_bits;
49     uint32_t crypt_method;
50     uint64_t l1_table_offset;
51 } QCowHeader;
52 
53 #define L2_CACHE_SIZE 16
54 
55 typedef struct BDRVQcowState {
56     BlockDriverState *hd;
57     int cluster_bits;
58     int cluster_size;
59     int cluster_sectors;
60     int l2_bits;
61     int l2_size;
62     int l1_size;
63     uint64_t cluster_offset_mask;
64     uint64_t l1_table_offset;
65     uint64_t *l1_table;
66     uint64_t *l2_cache;
67     uint64_t l2_cache_offsets[L2_CACHE_SIZE];
68     uint32_t l2_cache_counts[L2_CACHE_SIZE];
69     uint8_t *cluster_cache;
70     uint8_t *cluster_data;
71     uint64_t cluster_cache_offset;
72     uint32_t crypt_method; /* current crypt method, 0 if no key yet */
73     uint32_t crypt_method_header;
74     AES_KEY aes_encrypt_key;
75     AES_KEY aes_decrypt_key;
76 } BDRVQcowState;
77 
78 static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset);
79 
qcow_probe(const uint8_t * buf,int buf_size,const char * filename)80 static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
81 {
82     const QCowHeader *cow_header = (const void *)buf;
83 
84     if (buf_size >= sizeof(QCowHeader) &&
85         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
86         be32_to_cpu(cow_header->version) == QCOW_VERSION)
87         return 100;
88     else
89         return 0;
90 }
91 
qcow_open(BlockDriverState * bs,const char * filename,int flags)92 static int qcow_open(BlockDriverState *bs, const char *filename, int flags)
93 {
94     BDRVQcowState *s = bs->opaque;
95     int len, i, shift, ret;
96     QCowHeader header;
97 
98     ret = bdrv_file_open(&s->hd, filename, flags);
99     if (ret < 0)
100         return ret;
101     if (bdrv_pread(s->hd, 0, &header, sizeof(header)) != sizeof(header))
102         goto fail;
103     be32_to_cpus(&header.magic);
104     be32_to_cpus(&header.version);
105     be64_to_cpus(&header.backing_file_offset);
106     be32_to_cpus(&header.backing_file_size);
107     be32_to_cpus(&header.mtime);
108     be64_to_cpus(&header.size);
109     be32_to_cpus(&header.crypt_method);
110     be64_to_cpus(&header.l1_table_offset);
111 
112     if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
113         goto fail;
114     if (header.size <= 1 || header.cluster_bits < 9)
115         goto fail;
116     if (header.crypt_method > QCOW_CRYPT_AES)
117         goto fail;
118     s->crypt_method_header = header.crypt_method;
119     if (s->crypt_method_header)
120         bs->encrypted = 1;
121     s->cluster_bits = header.cluster_bits;
122     s->cluster_size = 1 << s->cluster_bits;
123     s->cluster_sectors = 1 << (s->cluster_bits - 9);
124     s->l2_bits = header.l2_bits;
125     s->l2_size = 1 << s->l2_bits;
126     bs->total_sectors = header.size / 512;
127     s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
128 
129     /* read the level 1 table */
130     shift = s->cluster_bits + s->l2_bits;
131     s->l1_size = (header.size + (1LL << shift) - 1) >> shift;
132 
133     s->l1_table_offset = header.l1_table_offset;
134     s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
135     if (!s->l1_table)
136         goto fail;
137     if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) !=
138         s->l1_size * sizeof(uint64_t))
139         goto fail;
140     for(i = 0;i < s->l1_size; i++) {
141         be64_to_cpus(&s->l1_table[i]);
142     }
143     /* alloc L2 cache */
144     s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
145     if (!s->l2_cache)
146         goto fail;
147     s->cluster_cache = qemu_malloc(s->cluster_size);
148     if (!s->cluster_cache)
149         goto fail;
150     s->cluster_data = qemu_malloc(s->cluster_size);
151     if (!s->cluster_data)
152         goto fail;
153     s->cluster_cache_offset = -1;
154 
155     /* read the backing file name */
156     if (header.backing_file_offset != 0) {
157         len = header.backing_file_size;
158         if (len > 1023)
159             len = 1023;
160         if (bdrv_pread(s->hd, header.backing_file_offset, bs->backing_file, len) != len)
161             goto fail;
162         bs->backing_file[len] = '\0';
163     }
164     return 0;
165 
166  fail:
167     qemu_free(s->l1_table);
168     qemu_free(s->l2_cache);
169     qemu_free(s->cluster_cache);
170     qemu_free(s->cluster_data);
171     bdrv_delete(s->hd);
172     return -1;
173 }
174 
qcow_set_key(BlockDriverState * bs,const char * key)175 static int qcow_set_key(BlockDriverState *bs, const char *key)
176 {
177     BDRVQcowState *s = bs->opaque;
178     uint8_t keybuf[16];
179     int len, i;
180 
181     memset(keybuf, 0, 16);
182     len = strlen(key);
183     if (len > 16)
184         len = 16;
185     /* XXX: we could compress the chars to 7 bits to increase
186        entropy */
187     for(i = 0;i < len;i++) {
188         keybuf[i] = key[i];
189     }
190     s->crypt_method = s->crypt_method_header;
191 
192     if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
193         return -1;
194     if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
195         return -1;
196 #if 0
197     /* test */
198     {
199         uint8_t in[16];
200         uint8_t out[16];
201         uint8_t tmp[16];
202         for(i=0;i<16;i++)
203             in[i] = i;
204         AES_encrypt(in, tmp, &s->aes_encrypt_key);
205         AES_decrypt(tmp, out, &s->aes_decrypt_key);
206         for(i = 0; i < 16; i++)
207             printf(" %02x", tmp[i]);
208         printf("\n");
209         for(i = 0; i < 16; i++)
210             printf(" %02x", out[i]);
211         printf("\n");
212     }
213 #endif
214     return 0;
215 }
216 
217 /* The crypt function is compatible with the linux cryptoloop
218    algorithm for < 4 GB images. NOTE: out_buf == in_buf is
219    supported */
encrypt_sectors(BDRVQcowState * s,int64_t sector_num,uint8_t * out_buf,const uint8_t * in_buf,int nb_sectors,int enc,const AES_KEY * key)220 static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
221                             uint8_t *out_buf, const uint8_t *in_buf,
222                             int nb_sectors, int enc,
223                             const AES_KEY *key)
224 {
225     union {
226         uint64_t ll[2];
227         uint8_t b[16];
228     } ivec;
229     int i;
230 
231     for(i = 0; i < nb_sectors; i++) {
232         ivec.ll[0] = cpu_to_le64(sector_num);
233         ivec.ll[1] = 0;
234         AES_cbc_encrypt(in_buf, out_buf, 512, key,
235                         ivec.b, enc);
236         sector_num++;
237         in_buf += 512;
238         out_buf += 512;
239     }
240 }
241 
242 /* 'allocate' is:
243  *
244  * 0 to not allocate.
245  *
246  * 1 to allocate a normal cluster (for sector indexes 'n_start' to
247  * 'n_end')
248  *
249  * 2 to allocate a compressed cluster of size
250  * 'compressed_size'. 'compressed_size' must be > 0 and <
251  * cluster_size
252  *
253  * return 0 if not allocated.
254  */
get_cluster_offset(BlockDriverState * bs,uint64_t offset,int allocate,int compressed_size,int n_start,int n_end)255 static uint64_t get_cluster_offset(BlockDriverState *bs,
256                                    uint64_t offset, int allocate,
257                                    int compressed_size,
258                                    int n_start, int n_end)
259 {
260     BDRVQcowState *s = bs->opaque;
261     int min_index, i, j, l1_index, l2_index;
262     uint64_t l2_offset, *l2_table, cluster_offset, tmp;
263     uint32_t min_count;
264     int new_l2_table;
265 
266     l1_index = offset >> (s->l2_bits + s->cluster_bits);
267     l2_offset = s->l1_table[l1_index];
268     new_l2_table = 0;
269     if (!l2_offset) {
270         if (!allocate)
271             return 0;
272         /* allocate a new l2 entry */
273         l2_offset = bdrv_getlength(s->hd);
274         /* round to cluster size */
275         l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
276         /* update the L1 entry */
277         s->l1_table[l1_index] = l2_offset;
278         tmp = cpu_to_be64(l2_offset);
279         if (bdrv_pwrite(s->hd, s->l1_table_offset + l1_index * sizeof(tmp),
280                         &tmp, sizeof(tmp)) != sizeof(tmp))
281             return 0;
282         new_l2_table = 1;
283     }
284     for(i = 0; i < L2_CACHE_SIZE; i++) {
285         if (l2_offset == s->l2_cache_offsets[i]) {
286             /* increment the hit count */
287             if (++s->l2_cache_counts[i] == 0xffffffff) {
288                 for(j = 0; j < L2_CACHE_SIZE; j++) {
289                     s->l2_cache_counts[j] >>= 1;
290                 }
291             }
292             l2_table = s->l2_cache + (i << s->l2_bits);
293             goto found;
294         }
295     }
296     /* not found: load a new entry in the least used one */
297     min_index = 0;
298     min_count = 0xffffffff;
299     for(i = 0; i < L2_CACHE_SIZE; i++) {
300         if (s->l2_cache_counts[i] < min_count) {
301             min_count = s->l2_cache_counts[i];
302             min_index = i;
303         }
304     }
305     l2_table = s->l2_cache + (min_index << s->l2_bits);
306     if (new_l2_table) {
307         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
308         if (bdrv_pwrite(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
309             s->l2_size * sizeof(uint64_t))
310             return 0;
311     } else {
312         if (bdrv_pread(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
313             s->l2_size * sizeof(uint64_t))
314             return 0;
315     }
316     s->l2_cache_offsets[min_index] = l2_offset;
317     s->l2_cache_counts[min_index] = 1;
318  found:
319     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
320     cluster_offset = be64_to_cpu(l2_table[l2_index]);
321     if (!cluster_offset ||
322         ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
323         if (!allocate)
324             return 0;
325         /* allocate a new cluster */
326         if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
327             (n_end - n_start) < s->cluster_sectors) {
328             /* if the cluster is already compressed, we must
329                decompress it in the case it is not completely
330                overwritten */
331             if (decompress_cluster(s, cluster_offset) < 0)
332                 return 0;
333             cluster_offset = bdrv_getlength(s->hd);
334             cluster_offset = (cluster_offset + s->cluster_size - 1) &
335                 ~(s->cluster_size - 1);
336             /* write the cluster content */
337             if (bdrv_pwrite(s->hd, cluster_offset, s->cluster_cache, s->cluster_size) !=
338                 s->cluster_size)
339                 return -1;
340         } else {
341             cluster_offset = bdrv_getlength(s->hd);
342             /* round to cluster size */
343             cluster_offset = (cluster_offset + s->cluster_size - 1) &
344                 ~(s->cluster_size - 1);
345             bdrv_truncate(s->hd, cluster_offset + s->cluster_size);
346             /* if encrypted, we must initialize the cluster
347                content which won't be written */
348             if (s->crypt_method &&
349                 (n_end - n_start) < s->cluster_sectors) {
350                 uint64_t start_sect;
351                 start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
352                 memset(s->cluster_data + 512, 0x00, 512);
353                 for(i = 0; i < s->cluster_sectors; i++) {
354                     if (i < n_start || i >= n_end) {
355                         encrypt_sectors(s, start_sect + i,
356                                         s->cluster_data,
357                                         s->cluster_data + 512, 1, 1,
358                                         &s->aes_encrypt_key);
359                         if (bdrv_pwrite(s->hd, cluster_offset + i * 512,
360                                         s->cluster_data, 512) != 512)
361                             return -1;
362                     }
363                 }
364             }
365         }
366         /* update L2 table */
367         tmp = cpu_to_be64(cluster_offset);
368         l2_table[l2_index] = tmp;
369         if (bdrv_pwrite(s->hd,
370                         l2_offset + l2_index * sizeof(tmp), &tmp, sizeof(tmp)) != sizeof(tmp))
371             return 0;
372     }
373     return cluster_offset;
374 }
375 
qcow_is_allocated(BlockDriverState * bs,int64_t sector_num,int nb_sectors,int * pnum)376 static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
377                              int nb_sectors, int *pnum)
378 {
379     BDRVQcowState *s = bs->opaque;
380     int index_in_cluster, n;
381     uint64_t cluster_offset;
382 
383     cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
384     index_in_cluster = sector_num & (s->cluster_sectors - 1);
385     n = s->cluster_sectors - index_in_cluster;
386     if (n > nb_sectors)
387         n = nb_sectors;
388     *pnum = n;
389     return (cluster_offset != 0);
390 }
391 
decompress_buffer(uint8_t * out_buf,int out_buf_size,const uint8_t * buf,int buf_size)392 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
393                              const uint8_t *buf, int buf_size)
394 {
395     z_stream strm1, *strm = &strm1;
396     int ret, out_len;
397 
398     memset(strm, 0, sizeof(*strm));
399 
400     strm->next_in = (uint8_t *)buf;
401     strm->avail_in = buf_size;
402     strm->next_out = out_buf;
403     strm->avail_out = out_buf_size;
404 
405     ret = inflateInit2(strm, -12);
406     if (ret != Z_OK)
407         return -1;
408     ret = inflate(strm, Z_FINISH);
409     out_len = strm->next_out - out_buf;
410     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
411         out_len != out_buf_size) {
412         inflateEnd(strm);
413         return -1;
414     }
415     inflateEnd(strm);
416     return 0;
417 }
418 
decompress_cluster(BDRVQcowState * s,uint64_t cluster_offset)419 static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset)
420 {
421     int ret, csize;
422     uint64_t coffset;
423 
424     coffset = cluster_offset & s->cluster_offset_mask;
425     if (s->cluster_cache_offset != coffset) {
426         csize = cluster_offset >> (63 - s->cluster_bits);
427         csize &= (s->cluster_size - 1);
428         ret = bdrv_pread(s->hd, coffset, s->cluster_data, csize);
429         if (ret != csize)
430             return -1;
431         if (decompress_buffer(s->cluster_cache, s->cluster_size,
432                               s->cluster_data, csize) < 0) {
433             return -1;
434         }
435         s->cluster_cache_offset = coffset;
436     }
437     return 0;
438 }
439 
440 #if 0
441 
442 static int qcow_read(BlockDriverState *bs, int64_t sector_num,
443                      uint8_t *buf, int nb_sectors)
444 {
445     BDRVQcowState *s = bs->opaque;
446     int ret, index_in_cluster, n;
447     uint64_t cluster_offset;
448 
449     while (nb_sectors > 0) {
450         cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
451         index_in_cluster = sector_num & (s->cluster_sectors - 1);
452         n = s->cluster_sectors - index_in_cluster;
453         if (n > nb_sectors)
454             n = nb_sectors;
455         if (!cluster_offset) {
456             if (bs->backing_hd) {
457                 /* read from the base image */
458                 ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
459                 if (ret < 0)
460                     return -1;
461             } else {
462                 memset(buf, 0, 512 * n);
463             }
464         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
465             if (decompress_cluster(s, cluster_offset) < 0)
466                 return -1;
467             memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
468         } else {
469             ret = bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
470             if (ret != n * 512)
471                 return -1;
472             if (s->crypt_method) {
473                 encrypt_sectors(s, sector_num, buf, buf, n, 0,
474                                 &s->aes_decrypt_key);
475             }
476         }
477         nb_sectors -= n;
478         sector_num += n;
479         buf += n * 512;
480     }
481     return 0;
482 }
483 #endif
484 
qcow_write(BlockDriverState * bs,int64_t sector_num,const uint8_t * buf,int nb_sectors)485 static int qcow_write(BlockDriverState *bs, int64_t sector_num,
486                      const uint8_t *buf, int nb_sectors)
487 {
488     BDRVQcowState *s = bs->opaque;
489     int ret, index_in_cluster, n;
490     uint64_t cluster_offset;
491 
492     while (nb_sectors > 0) {
493         index_in_cluster = sector_num & (s->cluster_sectors - 1);
494         n = s->cluster_sectors - index_in_cluster;
495         if (n > nb_sectors)
496             n = nb_sectors;
497         cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
498                                             index_in_cluster,
499                                             index_in_cluster + n);
500         if (!cluster_offset)
501             return -1;
502         if (s->crypt_method) {
503             encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
504                             &s->aes_encrypt_key);
505             ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512,
506                               s->cluster_data, n * 512);
507         } else {
508             ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
509         }
510         if (ret != n * 512)
511             return -1;
512         nb_sectors -= n;
513         sector_num += n;
514         buf += n * 512;
515     }
516     s->cluster_cache_offset = -1; /* disable compressed cache */
517     return 0;
518 }
519 
520 typedef struct QCowAIOCB {
521     BlockDriverAIOCB common;
522     int64_t sector_num;
523     uint8_t *buf;
524     int nb_sectors;
525     int n;
526     uint64_t cluster_offset;
527     uint8_t *cluster_data;
528     BlockDriverAIOCB *hd_aiocb;
529 } QCowAIOCB;
530 
qcow_aio_read_cb(void * opaque,int ret)531 static void qcow_aio_read_cb(void *opaque, int ret)
532 {
533     QCowAIOCB *acb = opaque;
534     BlockDriverState *bs = acb->common.bs;
535     BDRVQcowState *s = bs->opaque;
536     int index_in_cluster;
537 
538     acb->hd_aiocb = NULL;
539     if (ret < 0) {
540     fail:
541         acb->common.cb(acb->common.opaque, ret);
542         qemu_aio_release(acb);
543         return;
544     }
545 
546  redo:
547     /* post process the read buffer */
548     if (!acb->cluster_offset) {
549         /* nothing to do */
550     } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
551         /* nothing to do */
552     } else {
553         if (s->crypt_method) {
554             encrypt_sectors(s, acb->sector_num, acb->buf, acb->buf,
555                             acb->n, 0,
556                             &s->aes_decrypt_key);
557         }
558     }
559 
560     acb->nb_sectors -= acb->n;
561     acb->sector_num += acb->n;
562     acb->buf += acb->n * 512;
563 
564     if (acb->nb_sectors == 0) {
565         /* request completed */
566         acb->common.cb(acb->common.opaque, 0);
567         qemu_aio_release(acb);
568         return;
569     }
570 
571     /* prepare next AIO request */
572     acb->cluster_offset = get_cluster_offset(bs, acb->sector_num << 9,
573                                              0, 0, 0, 0);
574     index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
575     acb->n = s->cluster_sectors - index_in_cluster;
576     if (acb->n > acb->nb_sectors)
577         acb->n = acb->nb_sectors;
578 
579     if (!acb->cluster_offset) {
580         if (bs->backing_hd) {
581             /* read from the base image */
582             acb->hd_aiocb = bdrv_aio_read(bs->backing_hd,
583                 acb->sector_num, acb->buf, acb->n, qcow_aio_read_cb, acb);
584             if (acb->hd_aiocb == NULL)
585                 goto fail;
586         } else {
587             /* Note: in this case, no need to wait */
588             memset(acb->buf, 0, 512 * acb->n);
589             goto redo;
590         }
591     } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
592         /* add AIO support for compressed blocks ? */
593         if (decompress_cluster(s, acb->cluster_offset) < 0)
594             goto fail;
595         memcpy(acb->buf,
596                s->cluster_cache + index_in_cluster * 512, 512 * acb->n);
597         goto redo;
598     } else {
599         if ((acb->cluster_offset & 511) != 0) {
600             ret = -EIO;
601             goto fail;
602         }
603         acb->hd_aiocb = bdrv_aio_read(s->hd,
604                             (acb->cluster_offset >> 9) + index_in_cluster,
605                             acb->buf, acb->n, qcow_aio_read_cb, acb);
606         if (acb->hd_aiocb == NULL)
607             goto fail;
608     }
609 }
610 
qcow_aio_read(BlockDriverState * bs,int64_t sector_num,uint8_t * buf,int nb_sectors,BlockDriverCompletionFunc * cb,void * opaque)611 static BlockDriverAIOCB *qcow_aio_read(BlockDriverState *bs,
612         int64_t sector_num, uint8_t *buf, int nb_sectors,
613         BlockDriverCompletionFunc *cb, void *opaque)
614 {
615     QCowAIOCB *acb;
616 
617     acb = qemu_aio_get(bs, cb, opaque);
618     if (!acb)
619         return NULL;
620     acb->hd_aiocb = NULL;
621     acb->sector_num = sector_num;
622     acb->buf = buf;
623     acb->nb_sectors = nb_sectors;
624     acb->n = 0;
625     acb->cluster_offset = 0;
626 
627     qcow_aio_read_cb(acb, 0);
628     return &acb->common;
629 }
630 
qcow_aio_write_cb(void * opaque,int ret)631 static void qcow_aio_write_cb(void *opaque, int ret)
632 {
633     QCowAIOCB *acb = opaque;
634     BlockDriverState *bs = acb->common.bs;
635     BDRVQcowState *s = bs->opaque;
636     int index_in_cluster;
637     uint64_t cluster_offset;
638     const uint8_t *src_buf;
639 
640     acb->hd_aiocb = NULL;
641 
642     if (ret < 0) {
643     fail:
644         acb->common.cb(acb->common.opaque, ret);
645         qemu_aio_release(acb);
646         return;
647     }
648 
649     acb->nb_sectors -= acb->n;
650     acb->sector_num += acb->n;
651     acb->buf += acb->n * 512;
652 
653     if (acb->nb_sectors == 0) {
654         /* request completed */
655         acb->common.cb(acb->common.opaque, 0);
656         qemu_aio_release(acb);
657         return;
658     }
659 
660     index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
661     acb->n = s->cluster_sectors - index_in_cluster;
662     if (acb->n > acb->nb_sectors)
663         acb->n = acb->nb_sectors;
664     cluster_offset = get_cluster_offset(bs, acb->sector_num << 9, 1, 0,
665                                         index_in_cluster,
666                                         index_in_cluster + acb->n);
667     if (!cluster_offset || (cluster_offset & 511) != 0) {
668         ret = -EIO;
669         goto fail;
670     }
671     if (s->crypt_method) {
672         if (!acb->cluster_data) {
673             acb->cluster_data = qemu_mallocz(s->cluster_size);
674             if (!acb->cluster_data) {
675                 ret = -ENOMEM;
676                 goto fail;
677             }
678         }
679         encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->buf,
680                         acb->n, 1, &s->aes_encrypt_key);
681         src_buf = acb->cluster_data;
682     } else {
683         src_buf = acb->buf;
684     }
685     acb->hd_aiocb = bdrv_aio_write(s->hd,
686                                    (cluster_offset >> 9) + index_in_cluster,
687                                    src_buf, acb->n,
688                                    qcow_aio_write_cb, acb);
689     if (acb->hd_aiocb == NULL)
690         goto fail;
691 }
692 
qcow_aio_write(BlockDriverState * bs,int64_t sector_num,const uint8_t * buf,int nb_sectors,BlockDriverCompletionFunc * cb,void * opaque)693 static BlockDriverAIOCB *qcow_aio_write(BlockDriverState *bs,
694         int64_t sector_num, const uint8_t *buf, int nb_sectors,
695         BlockDriverCompletionFunc *cb, void *opaque)
696 {
697     BDRVQcowState *s = bs->opaque;
698     QCowAIOCB *acb;
699 
700     s->cluster_cache_offset = -1; /* disable compressed cache */
701 
702     acb = qemu_aio_get(bs, cb, opaque);
703     if (!acb)
704         return NULL;
705     acb->hd_aiocb = NULL;
706     acb->sector_num = sector_num;
707     acb->buf = (uint8_t *)buf;
708     acb->nb_sectors = nb_sectors;
709     acb->n = 0;
710 
711     qcow_aio_write_cb(acb, 0);
712     return &acb->common;
713 }
714 
qcow_aio_cancel(BlockDriverAIOCB * blockacb)715 static void qcow_aio_cancel(BlockDriverAIOCB *blockacb)
716 {
717     QCowAIOCB *acb = (QCowAIOCB *)blockacb;
718     if (acb->hd_aiocb)
719         bdrv_aio_cancel(acb->hd_aiocb);
720     qemu_aio_release(acb);
721 }
722 
qcow_close(BlockDriverState * bs)723 static void qcow_close(BlockDriverState *bs)
724 {
725     BDRVQcowState *s = bs->opaque;
726     qemu_free(s->l1_table);
727     qemu_free(s->l2_cache);
728     qemu_free(s->cluster_cache);
729     qemu_free(s->cluster_data);
730     bdrv_delete(s->hd);
731 }
732 
qcow_create(const char * filename,int64_t total_size,const char * backing_file,int flags)733 static int qcow_create(const char *filename, int64_t total_size,
734                       const char *backing_file, int flags)
735 {
736     int fd, header_size, backing_filename_len, l1_size, i, shift;
737     QCowHeader header;
738     uint64_t tmp;
739 
740     fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
741     if (fd < 0)
742         return -1;
743     memset(&header, 0, sizeof(header));
744     header.magic = cpu_to_be32(QCOW_MAGIC);
745     header.version = cpu_to_be32(QCOW_VERSION);
746     header.size = cpu_to_be64(total_size * 512);
747     header_size = sizeof(header);
748     backing_filename_len = 0;
749     if (backing_file) {
750         if (strcmp(backing_file, "fat:")) {
751             header.backing_file_offset = cpu_to_be64(header_size);
752             backing_filename_len = strlen(backing_file);
753             header.backing_file_size = cpu_to_be32(backing_filename_len);
754             header_size += backing_filename_len;
755         } else {
756             /* special backing file for vvfat */
757             backing_file = NULL;
758         }
759         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
760                                     unmodifyed sectors */
761         header.l2_bits = 12; /* 32 KB L2 tables */
762     } else {
763         header.cluster_bits = 12; /* 4 KB clusters */
764         header.l2_bits = 9; /* 4 KB L2 tables */
765     }
766     header_size = (header_size + 7) & ~7;
767     shift = header.cluster_bits + header.l2_bits;
768     l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift;
769 
770     header.l1_table_offset = cpu_to_be64(header_size);
771     if (flags & BLOCK_FLAG_ENCRYPT) {
772         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
773     } else {
774         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
775     }
776 
777     /* write all the data */
778     write(fd, &header, sizeof(header));
779     if (backing_file) {
780         write(fd, backing_file, backing_filename_len);
781     }
782     lseek(fd, header_size, SEEK_SET);
783     tmp = 0;
784     for(i = 0;i < l1_size; i++) {
785         write(fd, &tmp, sizeof(tmp));
786     }
787     close(fd);
788     return 0;
789 }
790 
qcow_make_empty(BlockDriverState * bs)791 static int qcow_make_empty(BlockDriverState *bs)
792 {
793     BDRVQcowState *s = bs->opaque;
794     uint32_t l1_length = s->l1_size * sizeof(uint64_t);
795     int ret;
796 
797     memset(s->l1_table, 0, l1_length);
798     if (bdrv_pwrite(s->hd, s->l1_table_offset, s->l1_table, l1_length) < 0)
799 	return -1;
800     ret = bdrv_truncate(s->hd, s->l1_table_offset + l1_length);
801     if (ret < 0)
802         return ret;
803 
804     memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
805     memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
806     memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
807 
808     return 0;
809 }
810 
811 /* XXX: put compressed sectors first, then all the cluster aligned
812    tables to avoid losing bytes in alignment */
qcow_write_compressed(BlockDriverState * bs,int64_t sector_num,const uint8_t * buf,int nb_sectors)813 static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
814                                  const uint8_t *buf, int nb_sectors)
815 {
816     BDRVQcowState *s = bs->opaque;
817     z_stream strm;
818     int ret, out_len;
819     uint8_t *out_buf;
820     uint64_t cluster_offset;
821 
822     if (nb_sectors != s->cluster_sectors)
823         return -EINVAL;
824 
825     out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
826     if (!out_buf)
827         return -1;
828 
829     /* best compression, small window, no zlib header */
830     memset(&strm, 0, sizeof(strm));
831     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
832                        Z_DEFLATED, -12,
833                        9, Z_DEFAULT_STRATEGY);
834     if (ret != 0) {
835         qemu_free(out_buf);
836         return -1;
837     }
838 
839     strm.avail_in = s->cluster_size;
840     strm.next_in = (uint8_t *)buf;
841     strm.avail_out = s->cluster_size;
842     strm.next_out = out_buf;
843 
844     ret = deflate(&strm, Z_FINISH);
845     if (ret != Z_STREAM_END && ret != Z_OK) {
846         qemu_free(out_buf);
847         deflateEnd(&strm);
848         return -1;
849     }
850     out_len = strm.next_out - out_buf;
851 
852     deflateEnd(&strm);
853 
854     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
855         /* could not compress: write normal cluster */
856         qcow_write(bs, sector_num, buf, s->cluster_sectors);
857     } else {
858         cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
859                                             out_len, 0, 0);
860         cluster_offset &= s->cluster_offset_mask;
861         if (bdrv_pwrite(s->hd, cluster_offset, out_buf, out_len) != out_len) {
862             qemu_free(out_buf);
863             return -1;
864         }
865     }
866 
867     qemu_free(out_buf);
868     return 0;
869 }
870 
qcow_flush(BlockDriverState * bs)871 static void qcow_flush(BlockDriverState *bs)
872 {
873     BDRVQcowState *s = bs->opaque;
874     bdrv_flush(s->hd);
875 }
876 
qcow_get_info(BlockDriverState * bs,BlockDriverInfo * bdi)877 static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
878 {
879     BDRVQcowState *s = bs->opaque;
880     bdi->cluster_size = s->cluster_size;
881     return 0;
882 }
883 
884 BlockDriver bdrv_qcow = {
885     "qcow",
886     sizeof(BDRVQcowState),
887     qcow_probe,
888     qcow_open,
889     NULL,
890     NULL,
891     qcow_close,
892     qcow_create,
893     qcow_flush,
894     qcow_is_allocated,
895     qcow_set_key,
896     qcow_make_empty,
897 
898     .bdrv_aio_read = qcow_aio_read,
899     .bdrv_aio_write = qcow_aio_write,
900     .bdrv_aio_cancel = qcow_aio_cancel,
901     .aiocb_size = sizeof(QCowAIOCB),
902     .bdrv_write_compressed = qcow_write_compressed,
903     .bdrv_get_info = qcow_get_info,
904 };
905