xref: /qemu/block/dmg.c (revision 2f28d2ff) 
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-common.h"
25 #include "block_int.h"
26 #include "bswap.h"
27 #include "module.h"
28 #include <zlib.h>
29 
30 typedef struct BDRVDMGState {
31     CoMutex lock;
32     /* each chunk contains a certain number of sectors,
33      * offsets[i] is the offset in the .dmg file,
34      * lengths[i] is the length of the compressed chunk,
35      * sectors[i] is the sector beginning at offsets[i],
36      * sectorcounts[i] is the number of sectors in that chunk,
37      * the sectors array is ordered
38      * 0<=i<n_chunks */
39 
40     uint32_t n_chunks;
41     uint32_t* types;
42     uint64_t* offsets;
43     uint64_t* lengths;
44     uint64_t* sectors;
45     uint64_t* sectorcounts;
46     uint32_t current_chunk;
47     uint8_t *compressed_chunk;
48     uint8_t *uncompressed_chunk;
49     z_stream zstream;
50 } BDRVDMGState;
51 
52 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
53 {
54     int len=strlen(filename);
55     if(len>4 && !strcmp(filename+len-4,".dmg"))
56 	return 2;
57     return 0;
58 }
59 
60 static off_t read_off(BlockDriverState *bs, int64_t offset)
61 {
62 	uint64_t buffer;
63 	if (bdrv_pread(bs->file, offset, &buffer, 8) < 8)
64 		return 0;
65 	return be64_to_cpu(buffer);
66 }
67 
68 static off_t read_uint32(BlockDriverState *bs, int64_t offset)
69 {
70 	uint32_t buffer;
71 	if (bdrv_pread(bs->file, offset, &buffer, 4) < 4)
72 		return 0;
73 	return be32_to_cpu(buffer);
74 }
75 
76 static int dmg_open(BlockDriverState *bs, int flags)
77 {
78     BDRVDMGState *s = bs->opaque;
79     off_t info_begin,info_end,last_in_offset,last_out_offset;
80     uint32_t count;
81     uint32_t max_compressed_size=1,max_sectors_per_chunk=1,i;
82     int64_t offset;
83 
84     bs->read_only = 1;
85     s->n_chunks = 0;
86     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
87 
88     /* read offset of info blocks */
89     offset = bdrv_getlength(bs->file);
90     if (offset < 0) {
91         goto fail;
92     }
93     offset -= 0x1d8;
94 
95     info_begin = read_off(bs, offset);
96     if (info_begin == 0) {
97 	goto fail;
98     }
99 
100     if (read_uint32(bs, info_begin) != 0x100) {
101         goto fail;
102     }
103 
104     count = read_uint32(bs, info_begin + 4);
105     if (count == 0) {
106         goto fail;
107     }
108     info_end = info_begin + count;
109 
110     offset = info_begin + 0x100;
111 
112     /* read offsets */
113     last_in_offset = last_out_offset = 0;
114     while (offset < info_end) {
115         uint32_t type;
116 
117 	count = read_uint32(bs, offset);
118 	if(count==0)
119 	    goto fail;
120         offset += 4;
121 
122 	type = read_uint32(bs, offset);
123 	if (type == 0x6d697368 && count >= 244) {
124 	    int new_size, chunk_count;
125 
126             offset += 4;
127             offset += 200;
128 
129 	    chunk_count = (count-204)/40;
130 	    new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
131 	    s->types = g_realloc(s->types, new_size/2);
132 	    s->offsets = g_realloc(s->offsets, new_size);
133 	    s->lengths = g_realloc(s->lengths, new_size);
134 	    s->sectors = g_realloc(s->sectors, new_size);
135 	    s->sectorcounts = g_realloc(s->sectorcounts, new_size);
136 
137 	    for(i=s->n_chunks;i<s->n_chunks+chunk_count;i++) {
138 		s->types[i] = read_uint32(bs, offset);
139 		offset += 4;
140 		if(s->types[i]!=0x80000005 && s->types[i]!=1 && s->types[i]!=2) {
141 		    if(s->types[i]==0xffffffff) {
142 			last_in_offset = s->offsets[i-1]+s->lengths[i-1];
143 			last_out_offset = s->sectors[i-1]+s->sectorcounts[i-1];
144 		    }
145 		    chunk_count--;
146 		    i--;
147 		    offset += 36;
148 		    continue;
149 		}
150 		offset += 4;
151 
152 		s->sectors[i] = last_out_offset+read_off(bs, offset);
153 		offset += 8;
154 
155 		s->sectorcounts[i] = read_off(bs, offset);
156 		offset += 8;
157 
158 		s->offsets[i] = last_in_offset+read_off(bs, offset);
159 		offset += 8;
160 
161 		s->lengths[i] = read_off(bs, offset);
162 		offset += 8;
163 
164 		if(s->lengths[i]>max_compressed_size)
165 		    max_compressed_size = s->lengths[i];
166 		if(s->sectorcounts[i]>max_sectors_per_chunk)
167 		    max_sectors_per_chunk = s->sectorcounts[i];
168 	    }
169 	    s->n_chunks+=chunk_count;
170 	}
171     }
172 
173     /* initialize zlib engine */
174     s->compressed_chunk = g_malloc(max_compressed_size+1);
175     s->uncompressed_chunk = g_malloc(512*max_sectors_per_chunk);
176     if(inflateInit(&s->zstream) != Z_OK)
177 	goto fail;
178 
179     s->current_chunk = s->n_chunks;
180 
181     qemu_co_mutex_init(&s->lock);
182     return 0;
183 fail:
184     return -1;
185 }
186 
187 static inline int is_sector_in_chunk(BDRVDMGState* s,
188 		uint32_t chunk_num,int sector_num)
189 {
190     if(chunk_num>=s->n_chunks || s->sectors[chunk_num]>sector_num ||
191 	    s->sectors[chunk_num]+s->sectorcounts[chunk_num]<=sector_num)
192 	return 0;
193     else
194 	return -1;
195 }
196 
197 static inline uint32_t search_chunk(BDRVDMGState* s,int sector_num)
198 {
199     /* binary search */
200     uint32_t chunk1=0,chunk2=s->n_chunks,chunk3;
201     while(chunk1!=chunk2) {
202 	chunk3 = (chunk1+chunk2)/2;
203 	if(s->sectors[chunk3]>sector_num)
204 	    chunk2 = chunk3;
205 	else if(s->sectors[chunk3]+s->sectorcounts[chunk3]>sector_num)
206 	    return chunk3;
207 	else
208 	    chunk1 = chunk3;
209     }
210     return s->n_chunks; /* error */
211 }
212 
213 static inline int dmg_read_chunk(BlockDriverState *bs, int sector_num)
214 {
215     BDRVDMGState *s = bs->opaque;
216 
217     if(!is_sector_in_chunk(s,s->current_chunk,sector_num)) {
218 	int ret;
219 	uint32_t chunk = search_chunk(s,sector_num);
220 
221 	if(chunk>=s->n_chunks)
222 	    return -1;
223 
224 	s->current_chunk = s->n_chunks;
225 	switch(s->types[chunk]) {
226 	case 0x80000005: { /* zlib compressed */
227 	    int i;
228 
229 	    /* we need to buffer, because only the chunk as whole can be
230 	     * inflated. */
231 	    i=0;
232 	    do {
233                 ret = bdrv_pread(bs->file, s->offsets[chunk] + i,
234                                  s->compressed_chunk+i, s->lengths[chunk]-i);
235 		if(ret<0 && errno==EINTR)
236 		    ret=0;
237 		i+=ret;
238 	    } while(ret>=0 && ret+i<s->lengths[chunk]);
239 
240 	    if (ret != s->lengths[chunk])
241 		return -1;
242 
243 	    s->zstream.next_in = s->compressed_chunk;
244 	    s->zstream.avail_in = s->lengths[chunk];
245 	    s->zstream.next_out = s->uncompressed_chunk;
246 	    s->zstream.avail_out = 512*s->sectorcounts[chunk];
247 	    ret = inflateReset(&s->zstream);
248 	    if(ret != Z_OK)
249 		return -1;
250 	    ret = inflate(&s->zstream, Z_FINISH);
251 	    if(ret != Z_STREAM_END || s->zstream.total_out != 512*s->sectorcounts[chunk])
252 		return -1;
253 	    break; }
254 	case 1: /* copy */
255 	    ret = bdrv_pread(bs->file, s->offsets[chunk],
256                              s->uncompressed_chunk, s->lengths[chunk]);
257 	    if (ret != s->lengths[chunk])
258 		return -1;
259 	    break;
260 	case 2: /* zero */
261 	    memset(s->uncompressed_chunk, 0, 512*s->sectorcounts[chunk]);
262 	    break;
263 	}
264 	s->current_chunk = chunk;
265     }
266     return 0;
267 }
268 
269 static int dmg_read(BlockDriverState *bs, int64_t sector_num,
270                     uint8_t *buf, int nb_sectors)
271 {
272     BDRVDMGState *s = bs->opaque;
273     int i;
274 
275     for(i=0;i<nb_sectors;i++) {
276 	uint32_t sector_offset_in_chunk;
277 	if(dmg_read_chunk(bs, sector_num+i) != 0)
278 	    return -1;
279 	sector_offset_in_chunk = sector_num+i-s->sectors[s->current_chunk];
280 	memcpy(buf+i*512,s->uncompressed_chunk+sector_offset_in_chunk*512,512);
281     }
282     return 0;
283 }
284 
285 static coroutine_fn int dmg_co_read(BlockDriverState *bs, int64_t sector_num,
286                                     uint8_t *buf, int nb_sectors)
287 {
288     int ret;
289     BDRVDMGState *s = bs->opaque;
290     qemu_co_mutex_lock(&s->lock);
291     ret = dmg_read(bs, sector_num, buf, nb_sectors);
292     qemu_co_mutex_unlock(&s->lock);
293     return ret;
294 }
295 
296 static void dmg_close(BlockDriverState *bs)
297 {
298     BDRVDMGState *s = bs->opaque;
299     if(s->n_chunks>0) {
300 	free(s->types);
301 	free(s->offsets);
302 	free(s->lengths);
303 	free(s->sectors);
304 	free(s->sectorcounts);
305     }
306     free(s->compressed_chunk);
307     free(s->uncompressed_chunk);
308     inflateEnd(&s->zstream);
309 }
310 
311 static BlockDriver bdrv_dmg = {
312     .format_name	= "dmg",
313     .instance_size	= sizeof(BDRVDMGState),
314     .bdrv_probe		= dmg_probe,
315     .bdrv_open		= dmg_open,
316     .bdrv_read          = dmg_co_read,
317     .bdrv_close		= dmg_close,
318 };
319 
320 static void bdrv_dmg_init(void)
321 {
322     bdrv_register(&bdrv_dmg);
323 }
324 
325 block_init(bdrv_dmg_init);
326