xref: /openbmc/qemu/block/dmg.c (revision 17252536)
1 /*
2  * QEMU Block driver for DMG images
3  *
4  * Copyright (c) 2004 Johannes E. Schindelin
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/osdep.h"
25 #include "qapi/error.h"
26 #include "block/block-io.h"
27 #include "block/block_int.h"
28 #include "qemu/bswap.h"
29 #include "qemu/error-report.h"
30 #include "qemu/module.h"
31 #include "qemu/memalign.h"
32 #include "dmg.h"
33 
34 BdrvDmgUncompressFunc *dmg_uncompress_bz2;
35 BdrvDmgUncompressFunc *dmg_uncompress_lzfse;
36 
37 enum {
38     /* Limit chunk sizes to prevent unreasonable amounts of memory being used
39      * or truncating when converting to 32-bit types
40      */
41     DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
42     DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
43 };
44 
45 enum {
46     /* DMG Block Type */
47     UDZE = 0, /* Zeroes */
48     UDRW,     /* RAW type */
49     UDIG,     /* Ignore */
50     UDCO = 0x80000004,
51     UDZO,
52     UDBZ,
53     ULFO,
54     UDCM = 0x7ffffffe, /* Comments */
55     UDLE = 0xffffffff  /* Last Entry */
56 };
57 
58 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
59 {
60     int len;
61 
62     if (!filename) {
63         return 0;
64     }
65 
66     len = strlen(filename);
67     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
68         return 2;
69     }
70     return 0;
71 }
72 
73 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
74 {
75     uint64_t buffer;
76     int ret;
77 
78     ret = bdrv_pread(bs->file, offset, 8, &buffer, 0);
79     if (ret < 0) {
80         return ret;
81     }
82 
83     *result = be64_to_cpu(buffer);
84     return 0;
85 }
86 
87 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
88 {
89     uint32_t buffer;
90     int ret;
91 
92     ret = bdrv_pread(bs->file, offset, 4, &buffer, 0);
93     if (ret < 0) {
94         return ret;
95     }
96 
97     *result = be32_to_cpu(buffer);
98     return 0;
99 }
100 
101 static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
102 {
103     return be64_to_cpu(*(uint64_t *)&buffer[offset]);
104 }
105 
106 static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
107 {
108     return be32_to_cpu(*(uint32_t *)&buffer[offset]);
109 }
110 
111 /* Increase max chunk sizes, if necessary.  This function is used to calculate
112  * the buffer sizes needed for compressed/uncompressed chunk I/O.
113  */
114 static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
115                                   uint32_t *max_compressed_size,
116                                   uint32_t *max_sectors_per_chunk)
117 {
118     uint32_t compressed_size = 0;
119     uint32_t uncompressed_sectors = 0;
120 
121     switch (s->types[chunk]) {
122     case UDZO: /* zlib compressed */
123     case UDBZ: /* bzip2 compressed */
124     case ULFO: /* lzfse compressed */
125         compressed_size = s->lengths[chunk];
126         uncompressed_sectors = s->sectorcounts[chunk];
127         break;
128     case UDRW: /* copy */
129         uncompressed_sectors = DIV_ROUND_UP(s->lengths[chunk], 512);
130         break;
131     case UDZE: /* zero */
132     case UDIG: /* ignore */
133         /* as the all-zeroes block may be large, it is treated specially: the
134          * sector is not copied from a large buffer, a simple memset is used
135          * instead. Therefore uncompressed_sectors does not need to be set. */
136         break;
137     }
138 
139     if (compressed_size > *max_compressed_size) {
140         *max_compressed_size = compressed_size;
141     }
142     if (uncompressed_sectors > *max_sectors_per_chunk) {
143         *max_sectors_per_chunk = uncompressed_sectors;
144     }
145 }
146 
147 static int64_t dmg_find_koly_offset(BdrvChild *file, Error **errp)
148 {
149     BlockDriverState *file_bs = file->bs;
150     int64_t length;
151     int64_t offset = 0;
152     uint8_t buffer[515];
153     int i, ret;
154 
155     /* bdrv_getlength returns a multiple of block size (512), rounded up. Since
156      * dmg images can have odd sizes, try to look for the "koly" magic which
157      * marks the begin of the UDIF trailer (512 bytes). This magic can be found
158      * in the last 511 bytes of the second-last sector or the first 4 bytes of
159      * the last sector (search space: 515 bytes) */
160     length = bdrv_getlength(file_bs);
161     if (length < 0) {
162         error_setg_errno(errp, -length,
163             "Failed to get file size while reading UDIF trailer");
164         return length;
165     } else if (length < 512) {
166         error_setg(errp, "dmg file must be at least 512 bytes long");
167         return -EINVAL;
168     }
169     if (length > 511 + 512) {
170         offset = length - 511 - 512;
171     }
172     length = length < 515 ? length : 515;
173     ret = bdrv_pread(file, offset, length, buffer, 0);
174     if (ret < 0) {
175         error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
176         return ret;
177     }
178     for (i = 0; i < length - 3; i++) {
179         if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
180             buffer[i+2] == 'l' && buffer[i+3] == 'y') {
181             return offset + i;
182         }
183     }
184     error_setg(errp, "Could not locate UDIF trailer in dmg file");
185     return -EINVAL;
186 }
187 
188 /* used when building the sector table */
189 typedef struct DmgHeaderState {
190     /* used internally by dmg_read_mish_block to remember offsets of blocks
191      * across calls */
192     uint64_t data_fork_offset;
193     /* exported for dmg_open */
194     uint32_t max_compressed_size;
195     uint32_t max_sectors_per_chunk;
196 } DmgHeaderState;
197 
198 static bool dmg_is_known_block_type(uint32_t entry_type)
199 {
200     switch (entry_type) {
201     case UDZE:    /* zeros */
202     case UDRW:    /* uncompressed */
203     case UDIG:    /* ignore */
204     case UDZO:    /* zlib */
205         return true;
206     case UDBZ:    /* bzip2 */
207         return !!dmg_uncompress_bz2;
208     case ULFO:    /* lzfse */
209         return !!dmg_uncompress_lzfse;
210     default:
211         return false;
212     }
213 }
214 
215 static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
216                                uint8_t *buffer, uint32_t count)
217 {
218     uint32_t type, i;
219     int ret;
220     size_t new_size;
221     uint32_t chunk_count;
222     int64_t offset = 0;
223     uint64_t data_offset;
224     uint64_t in_offset = ds->data_fork_offset;
225     uint64_t out_offset;
226 
227     type = buff_read_uint32(buffer, offset);
228     /* skip data that is not a valid MISH block (invalid magic or too small) */
229     if (type != 0x6d697368 || count < 244) {
230         /* assume success for now */
231         return 0;
232     }
233 
234     /* chunk offsets are relative to this sector number */
235     out_offset = buff_read_uint64(buffer, offset + 8);
236 
237     /* location in data fork for (compressed) blob (in bytes) */
238     data_offset = buff_read_uint64(buffer, offset + 0x18);
239     in_offset += data_offset;
240 
241     /* move to begin of chunk entries */
242     offset += 204;
243 
244     chunk_count = (count - 204) / 40;
245     new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
246     s->types = g_realloc(s->types, new_size / 2);
247     s->offsets = g_realloc(s->offsets, new_size);
248     s->lengths = g_realloc(s->lengths, new_size);
249     s->sectors = g_realloc(s->sectors, new_size);
250     s->sectorcounts = g_realloc(s->sectorcounts, new_size);
251 
252     for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
253         s->types[i] = buff_read_uint32(buffer, offset);
254         if (!dmg_is_known_block_type(s->types[i])) {
255             switch (s->types[i]) {
256             case UDBZ:
257                 warn_report_once("dmg-bzip2 module is missing, accessing bzip2 "
258                                  "compressed blocks will result in I/O errors");
259                 break;
260             case ULFO:
261                 warn_report_once("dmg-lzfse module is missing, accessing lzfse "
262                                  "compressed blocks will result in I/O errors");
263                 break;
264             case UDCM:
265             case UDLE:
266                 /* Comments and last entry can be ignored without problems */
267                 break;
268             default:
269                 warn_report_once("Image contains chunks of unknown type %x, "
270                                  "accessing them will result in I/O errors",
271                                  s->types[i]);
272                 break;
273             }
274             chunk_count--;
275             i--;
276             offset += 40;
277             continue;
278         }
279 
280         /* sector number */
281         s->sectors[i] = buff_read_uint64(buffer, offset + 8);
282         s->sectors[i] += out_offset;
283 
284         /* sector count */
285         s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
286 
287         /* all-zeroes sector (type UDZE and UDIG) does not need to be
288          * "uncompressed" and can therefore be unbounded. */
289         if (s->types[i] != UDZE && s->types[i] != UDIG
290             && s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
291             error_report("sector count %" PRIu64 " for chunk %" PRIu32
292                          " is larger than max (%u)",
293                          s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
294             ret = -EINVAL;
295             goto fail;
296         }
297 
298         /* offset in (compressed) data fork */
299         s->offsets[i] = buff_read_uint64(buffer, offset + 0x18);
300         s->offsets[i] += in_offset;
301 
302         /* length in (compressed) data fork */
303         s->lengths[i] = buff_read_uint64(buffer, offset + 0x20);
304 
305         if (s->lengths[i] > DMG_LENGTHS_MAX) {
306             error_report("length %" PRIu64 " for chunk %" PRIu32
307                          " is larger than max (%u)",
308                          s->lengths[i], i, DMG_LENGTHS_MAX);
309             ret = -EINVAL;
310             goto fail;
311         }
312 
313         update_max_chunk_size(s, i, &ds->max_compressed_size,
314                               &ds->max_sectors_per_chunk);
315         offset += 40;
316     }
317     s->n_chunks += chunk_count;
318     return 0;
319 
320 fail:
321     return ret;
322 }
323 
324 static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
325                                   uint64_t info_begin, uint64_t info_length)
326 {
327     BDRVDMGState *s = bs->opaque;
328     int ret;
329     uint32_t count, rsrc_data_offset;
330     uint8_t *buffer = NULL;
331     uint64_t info_end;
332     uint64_t offset;
333 
334     /* read offset from begin of resource fork (info_begin) to resource data */
335     ret = read_uint32(bs, info_begin, &rsrc_data_offset);
336     if (ret < 0) {
337         goto fail;
338     } else if (rsrc_data_offset > info_length) {
339         ret = -EINVAL;
340         goto fail;
341     }
342 
343     /* read length of resource data */
344     ret = read_uint32(bs, info_begin + 8, &count);
345     if (ret < 0) {
346         goto fail;
347     } else if (count == 0 || rsrc_data_offset + count > info_length) {
348         ret = -EINVAL;
349         goto fail;
350     }
351 
352     /* begin of resource data (consisting of one or more resources) */
353     offset = info_begin + rsrc_data_offset;
354 
355     /* end of resource data (there is possibly a following resource map
356      * which will be ignored). */
357     info_end = offset + count;
358 
359     /* read offsets (mish blocks) from one or more resources in resource data */
360     while (offset < info_end) {
361         /* size of following resource */
362         ret = read_uint32(bs, offset, &count);
363         if (ret < 0) {
364             goto fail;
365         } else if (count == 0 || count > info_end - offset) {
366             ret = -EINVAL;
367             goto fail;
368         }
369         offset += 4;
370 
371         buffer = g_realloc(buffer, count);
372         ret = bdrv_pread(bs->file, offset, count, buffer, 0);
373         if (ret < 0) {
374             goto fail;
375         }
376 
377         ret = dmg_read_mish_block(s, ds, buffer, count);
378         if (ret < 0) {
379             goto fail;
380         }
381         /* advance offset by size of resource */
382         offset += count;
383     }
384     ret = 0;
385 
386 fail:
387     g_free(buffer);
388     return ret;
389 }
390 
391 static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
392                               uint64_t info_begin, uint64_t info_length)
393 {
394     BDRVDMGState *s = bs->opaque;
395     int ret;
396     uint8_t *buffer = NULL;
397     char *data_begin, *data_end;
398 
399     /* Have at least some length to avoid NULL for g_malloc. Attempt to set a
400      * safe upper cap on the data length. A test sample had a XML length of
401      * about 1 MiB. */
402     if (info_length == 0 || info_length > 16 * 1024 * 1024) {
403         ret = -EINVAL;
404         goto fail;
405     }
406 
407     buffer = g_malloc(info_length + 1);
408     buffer[info_length] = '\0';
409     ret = bdrv_pread(bs->file, info_begin, info_length, buffer, 0);
410     if (ret < 0) {
411         ret = -EINVAL;
412         goto fail;
413     }
414 
415     /* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
416      * decode. The actual data element has 431 (0x1af) bytes which includes tabs
417      * and line feeds. */
418     data_end = (char *)buffer;
419     while ((data_begin = strstr(data_end, "<data>")) != NULL) {
420         guchar *mish;
421         gsize out_len = 0;
422 
423         data_begin += 6;
424         data_end = strstr(data_begin, "</data>");
425         /* malformed XML? */
426         if (data_end == NULL) {
427             ret = -EINVAL;
428             goto fail;
429         }
430         *data_end++ = '\0';
431         mish = g_base64_decode(data_begin, &out_len);
432         ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
433         g_free(mish);
434         if (ret < 0) {
435             goto fail;
436         }
437     }
438     ret = 0;
439 
440 fail:
441     g_free(buffer);
442     return ret;
443 }
444 
445 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
446                     Error **errp)
447 {
448     BDRVDMGState *s = bs->opaque;
449     DmgHeaderState ds;
450     uint64_t rsrc_fork_offset, rsrc_fork_length;
451     uint64_t plist_xml_offset, plist_xml_length;
452     int64_t offset;
453     int ret;
454 
455     bdrv_graph_rdlock_main_loop();
456     ret = bdrv_apply_auto_read_only(bs, NULL, errp);
457     bdrv_graph_rdunlock_main_loop();
458     if (ret < 0) {
459         return ret;
460     }
461 
462     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
463     if (ret < 0) {
464         return ret;
465     }
466     /*
467      * NB: if uncompress submodules are absent,
468      * ie block_module_load return value == 0, the function pointers
469      * dmg_uncompress_bz2 and dmg_uncompress_lzfse will be NULL.
470      */
471     if (block_module_load("dmg-bz2", errp) < 0) {
472         return -EINVAL;
473     }
474     if (block_module_load("dmg-lzfse", errp) < 0) {
475         return -EINVAL;
476     }
477 
478     s->n_chunks = 0;
479     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
480     /* used by dmg_read_mish_block to keep track of the current I/O position */
481     ds.data_fork_offset = 0;
482     ds.max_compressed_size = 1;
483     ds.max_sectors_per_chunk = 1;
484 
485     /* locate the UDIF trailer */
486     offset = dmg_find_koly_offset(bs->file, errp);
487     if (offset < 0) {
488         ret = offset;
489         goto fail;
490     }
491 
492     /* offset of data fork (DataForkOffset) */
493     ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
494     if (ret < 0) {
495         goto fail;
496     } else if (ds.data_fork_offset > offset) {
497         ret = -EINVAL;
498         goto fail;
499     }
500 
501     /* offset of resource fork (RsrcForkOffset) */
502     ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
503     if (ret < 0) {
504         goto fail;
505     }
506     ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
507     if (ret < 0) {
508         goto fail;
509     }
510     if (rsrc_fork_offset >= offset ||
511         rsrc_fork_length > offset - rsrc_fork_offset) {
512         ret = -EINVAL;
513         goto fail;
514     }
515     /* offset of property list (XMLOffset) */
516     ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
517     if (ret < 0) {
518         goto fail;
519     }
520     ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
521     if (ret < 0) {
522         goto fail;
523     }
524     if (plist_xml_offset >= offset ||
525         plist_xml_length > offset - plist_xml_offset) {
526         ret = -EINVAL;
527         goto fail;
528     }
529     ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
530     if (ret < 0) {
531         goto fail;
532     }
533     if (bs->total_sectors < 0) {
534         ret = -EINVAL;
535         goto fail;
536     }
537     if (rsrc_fork_length != 0) {
538         ret = dmg_read_resource_fork(bs, &ds,
539                                      rsrc_fork_offset, rsrc_fork_length);
540         if (ret < 0) {
541             goto fail;
542         }
543     } else if (plist_xml_length != 0) {
544         ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
545         if (ret < 0) {
546             goto fail;
547         }
548     } else {
549         ret = -EINVAL;
550         goto fail;
551     }
552 
553     /* initialize zlib engine */
554     s->compressed_chunk = qemu_try_blockalign(bs->file->bs,
555                                               ds.max_compressed_size + 1);
556     s->uncompressed_chunk = qemu_try_blockalign(bs->file->bs,
557                                                 512 * ds.max_sectors_per_chunk);
558     if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
559         ret = -ENOMEM;
560         goto fail;
561     }
562 
563     if (inflateInit(&s->zstream) != Z_OK) {
564         ret = -EINVAL;
565         goto fail;
566     }
567 
568     s->current_chunk = s->n_chunks;
569 
570     qemu_co_mutex_init(&s->lock);
571     return 0;
572 
573 fail:
574     g_free(s->types);
575     g_free(s->offsets);
576     g_free(s->lengths);
577     g_free(s->sectors);
578     g_free(s->sectorcounts);
579     qemu_vfree(s->compressed_chunk);
580     qemu_vfree(s->uncompressed_chunk);
581     return ret;
582 }
583 
584 static void dmg_refresh_limits(BlockDriverState *bs, Error **errp)
585 {
586     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
587 }
588 
589 static inline int is_sector_in_chunk(BDRVDMGState *s,
590                 uint32_t chunk_num, uint64_t sector_num)
591 {
592     if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
593             s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
594         return 0;
595     } else {
596         return -1;
597     }
598 }
599 
600 static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
601 {
602     /* binary search */
603     uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
604     while (chunk1 <= chunk2) {
605         chunk3 = (chunk1 + chunk2) / 2;
606         if (s->sectors[chunk3] > sector_num) {
607             if (chunk3 == 0) {
608                 goto err;
609             }
610             chunk2 = chunk3 - 1;
611         } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
612             return chunk3;
613         } else {
614             chunk1 = chunk3 + 1;
615         }
616     }
617 err:
618     return s->n_chunks; /* error */
619 }
620 
621 static int coroutine_fn GRAPH_RDLOCK
622 dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
623 {
624     BDRVDMGState *s = bs->opaque;
625 
626     if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
627         int ret;
628         uint32_t chunk = search_chunk(s, sector_num);
629 
630         if (chunk >= s->n_chunks) {
631             return -1;
632         }
633 
634         s->current_chunk = s->n_chunks;
635         switch (s->types[chunk]) { /* block entry type */
636         case UDZO: { /* zlib compressed */
637             /* we need to buffer, because only the chunk as whole can be
638              * inflated. */
639             ret = bdrv_co_pread(bs->file, s->offsets[chunk], s->lengths[chunk],
640                                 s->compressed_chunk, 0);
641             if (ret < 0) {
642                 return -1;
643             }
644 
645             s->zstream.next_in = s->compressed_chunk;
646             s->zstream.avail_in = s->lengths[chunk];
647             s->zstream.next_out = s->uncompressed_chunk;
648             s->zstream.avail_out = 512 * s->sectorcounts[chunk];
649             ret = inflateReset(&s->zstream);
650             if (ret != Z_OK) {
651                 return -1;
652             }
653             ret = inflate(&s->zstream, Z_FINISH);
654             if (ret != Z_STREAM_END ||
655                 s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
656                 return -1;
657             }
658             break; }
659         case UDBZ: /* bzip2 compressed */
660             if (!dmg_uncompress_bz2) {
661                 break;
662             }
663             /* we need to buffer, because only the chunk as whole can be
664              * inflated. */
665             ret = bdrv_co_pread(bs->file, s->offsets[chunk], s->lengths[chunk],
666                                 s->compressed_chunk, 0);
667             if (ret < 0) {
668                 return -1;
669             }
670 
671             ret = dmg_uncompress_bz2((char *)s->compressed_chunk,
672                                      (unsigned int) s->lengths[chunk],
673                                      (char *)s->uncompressed_chunk,
674                                      (unsigned int)
675                                          (512 * s->sectorcounts[chunk]));
676             if (ret < 0) {
677                 return ret;
678             }
679             break;
680         case ULFO:
681             if (!dmg_uncompress_lzfse) {
682                 break;
683             }
684             /* we need to buffer, because only the chunk as whole can be
685              * inflated. */
686             ret = bdrv_co_pread(bs->file, s->offsets[chunk], s->lengths[chunk],
687                                 s->compressed_chunk, 0);
688             if (ret < 0) {
689                 return -1;
690             }
691 
692             ret = dmg_uncompress_lzfse((char *)s->compressed_chunk,
693                                        (unsigned int) s->lengths[chunk],
694                                        (char *)s->uncompressed_chunk,
695                                        (unsigned int)
696                                            (512 * s->sectorcounts[chunk]));
697             if (ret < 0) {
698                 return ret;
699             }
700             break;
701         case UDRW: /* copy */
702             ret = bdrv_co_pread(bs->file, s->offsets[chunk], s->lengths[chunk],
703                                 s->uncompressed_chunk, 0);
704             if (ret < 0) {
705                 return -1;
706             }
707             break;
708         case UDZE: /* zeros */
709         case UDIG: /* ignore */
710             /* see dmg_read, it is treated specially. No buffer needs to be
711              * pre-filled, the zeroes can be set directly. */
712             break;
713         }
714         s->current_chunk = chunk;
715     }
716     return 0;
717 }
718 
719 static int coroutine_fn GRAPH_RDLOCK
720 dmg_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
721               QEMUIOVector *qiov, BdrvRequestFlags flags)
722 {
723     BDRVDMGState *s = bs->opaque;
724     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
725     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
726     int ret, i;
727 
728     assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
729     assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
730 
731     qemu_co_mutex_lock(&s->lock);
732 
733     for (i = 0; i < nb_sectors; i++) {
734         uint32_t sector_offset_in_chunk;
735         void *data;
736 
737         if (dmg_read_chunk(bs, sector_num + i) != 0) {
738             ret = -EIO;
739             goto fail;
740         }
741         /* Special case: current chunk is all zeroes. Do not perform a memcpy as
742          * s->uncompressed_chunk may be too small to cover the large all-zeroes
743          * section. dmg_read_chunk is called to find s->current_chunk */
744         if (s->types[s->current_chunk] == UDZE
745             || s->types[s->current_chunk] == UDIG) { /* all zeroes block entry */
746             qemu_iovec_memset(qiov, i * 512, 0, 512);
747             continue;
748         }
749         sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
750         data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
751         qemu_iovec_from_buf(qiov, i * 512, data, 512);
752     }
753 
754     ret = 0;
755 fail:
756     qemu_co_mutex_unlock(&s->lock);
757     return ret;
758 }
759 
760 static void dmg_close(BlockDriverState *bs)
761 {
762     BDRVDMGState *s = bs->opaque;
763 
764     g_free(s->types);
765     g_free(s->offsets);
766     g_free(s->lengths);
767     g_free(s->sectors);
768     g_free(s->sectorcounts);
769     qemu_vfree(s->compressed_chunk);
770     qemu_vfree(s->uncompressed_chunk);
771 
772     inflateEnd(&s->zstream);
773 }
774 
775 static BlockDriver bdrv_dmg = {
776     .format_name    = "dmg",
777     .instance_size  = sizeof(BDRVDMGState),
778     .bdrv_probe     = dmg_probe,
779     .bdrv_open      = dmg_open,
780     .bdrv_refresh_limits = dmg_refresh_limits,
781     .bdrv_child_perm     = bdrv_default_perms,
782     .bdrv_co_preadv = dmg_co_preadv,
783     .bdrv_close     = dmg_close,
784     .is_format      = true,
785 };
786 
787 static void bdrv_dmg_init(void)
788 {
789     bdrv_register(&bdrv_dmg);
790 }
791 
792 block_init(bdrv_dmg_init);
793