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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     int fd;
32 
33     /* each chunk contains a certain number of sectors,
34      * offsets[i] is the offset in the .dmg file,
35      * lengths[i] is the length of the compressed chunk,
36      * sectors[i] is the sector beginning at offsets[i],
37      * sectorcounts[i] is the number of sectors in that chunk,
38      * the sectors array is ordered
39      * 0<=i<n_chunks */
40 
41     uint32_t n_chunks;
42     uint32_t* types;
43     uint64_t* offsets;
44     uint64_t* lengths;
45     uint64_t* sectors;
46     uint64_t* sectorcounts;
47     uint32_t current_chunk;
48     uint8_t *compressed_chunk;
49     uint8_t *uncompressed_chunk;
50     z_stream zstream;
51 } BDRVDMGState;
52 
dmg_probe(const uint8_t * buf,int buf_size,const char * filename)53 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
54 {
55     int len=strlen(filename);
56     if(len>4 && !strcmp(filename+len-4,".dmg"))
57 	return 2;
58     return 0;
59 }
60 
read_off(int fd)61 static off_t read_off(int fd)
62 {
63 	uint64_t buffer;
64 	if(read(fd,&buffer,8)<8)
65 		return 0;
66 	return be64_to_cpu(buffer);
67 }
68 
read_uint32(int fd)69 static off_t read_uint32(int fd)
70 {
71 	uint32_t buffer;
72 	if(read(fd,&buffer,4)<4)
73 		return 0;
74 	return be32_to_cpu(buffer);
75 }
76 
dmg_open(BlockDriverState * bs,const char * filename,int flags)77 static int dmg_open(BlockDriverState *bs, const char *filename, int flags)
78 {
79     BDRVDMGState *s = bs->opaque;
80     off_t info_begin,info_end,last_in_offset,last_out_offset;
81     uint32_t count;
82     uint32_t max_compressed_size=1,max_sectors_per_chunk=1,i;
83 
84     s->fd = open(filename, O_RDONLY | O_BINARY);
85     if (s->fd < 0)
86         return -errno;
87     bs->read_only = 1;
88     s->n_chunks = 0;
89     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
90 
91     /* read offset of info blocks */
92     if(lseek(s->fd,-0x1d8,SEEK_END)<0) {
93 dmg_close:
94 	close(s->fd);
95 	/* open raw instead */
96 	bs->drv=bdrv_find_format("raw");
97 	return bs->drv->bdrv_open(bs, filename, flags);
98     }
99     info_begin=read_off(s->fd);
100     if(info_begin==0)
101 	goto dmg_close;
102     if(lseek(s->fd,info_begin,SEEK_SET)<0)
103 	goto dmg_close;
104     if(read_uint32(s->fd)!=0x100)
105 	goto dmg_close;
106     if((count = read_uint32(s->fd))==0)
107 	goto dmg_close;
108     info_end = info_begin+count;
109     if(lseek(s->fd,0xf8,SEEK_CUR)<0)
110 	goto dmg_close;
111 
112     /* read offsets */
113     last_in_offset = last_out_offset = 0;
114     while(lseek(s->fd,0,SEEK_CUR)<info_end) {
115         uint32_t type;
116 
117 	count = read_uint32(s->fd);
118 	if(count==0)
119 	    goto dmg_close;
120 	type = read_uint32(s->fd);
121 	if(type!=0x6d697368 || count<244)
122 	    lseek(s->fd,count-4,SEEK_CUR);
123 	else {
124 	    int new_size, chunk_count;
125 	    if(lseek(s->fd,200,SEEK_CUR)<0)
126 	        goto dmg_close;
127 	    chunk_count = (count-204)/40;
128 	    new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
129 	    s->types = qemu_realloc(s->types, new_size/2);
130 	    s->offsets = qemu_realloc(s->offsets, new_size);
131 	    s->lengths = qemu_realloc(s->lengths, new_size);
132 	    s->sectors = qemu_realloc(s->sectors, new_size);
133 	    s->sectorcounts = qemu_realloc(s->sectorcounts, new_size);
134 
135 	    for(i=s->n_chunks;i<s->n_chunks+chunk_count;i++) {
136 		s->types[i] = read_uint32(s->fd);
137 		if(s->types[i]!=0x80000005 && s->types[i]!=1 && s->types[i]!=2) {
138 		    if(s->types[i]==0xffffffff) {
139 			last_in_offset = s->offsets[i-1]+s->lengths[i-1];
140 			last_out_offset = s->sectors[i-1]+s->sectorcounts[i-1];
141 		    }
142 		    chunk_count--;
143 		    i--;
144 		    if(lseek(s->fd,36,SEEK_CUR)<0)
145 			goto dmg_close;
146 		    continue;
147 		}
148 		read_uint32(s->fd);
149 		s->sectors[i] = last_out_offset+read_off(s->fd);
150 		s->sectorcounts[i] = read_off(s->fd);
151 		s->offsets[i] = last_in_offset+read_off(s->fd);
152 		s->lengths[i] = read_off(s->fd);
153 		if(s->lengths[i]>max_compressed_size)
154 		    max_compressed_size = s->lengths[i];
155 		if(s->sectorcounts[i]>max_sectors_per_chunk)
156 		    max_sectors_per_chunk = s->sectorcounts[i];
157 	    }
158 	    s->n_chunks+=chunk_count;
159 	}
160     }
161 
162     /* initialize zlib engine */
163     s->compressed_chunk = qemu_malloc(max_compressed_size+1);
164     s->uncompressed_chunk = qemu_malloc(512*max_sectors_per_chunk);
165     if(inflateInit(&s->zstream) != Z_OK)
166 	goto dmg_close;
167 
168     s->current_chunk = s->n_chunks;
169 
170     return 0;
171 }
172 
is_sector_in_chunk(BDRVDMGState * s,uint32_t chunk_num,int sector_num)173 static inline int is_sector_in_chunk(BDRVDMGState* s,
174 		uint32_t chunk_num,int sector_num)
175 {
176     if(chunk_num>=s->n_chunks || s->sectors[chunk_num]>sector_num ||
177 	    s->sectors[chunk_num]+s->sectorcounts[chunk_num]<=sector_num)
178 	return 0;
179     else
180 	return -1;
181 }
182 
search_chunk(BDRVDMGState * s,int sector_num)183 static inline uint32_t search_chunk(BDRVDMGState* s,int sector_num)
184 {
185     /* binary search */
186     uint32_t chunk1=0,chunk2=s->n_chunks,chunk3;
187     while(chunk1!=chunk2) {
188 	chunk3 = (chunk1+chunk2)/2;
189 	if(s->sectors[chunk3]>sector_num)
190 	    chunk2 = chunk3;
191 	else if(s->sectors[chunk3]+s->sectorcounts[chunk3]>sector_num)
192 	    return chunk3;
193 	else
194 	    chunk1 = chunk3;
195     }
196     return s->n_chunks; /* error */
197 }
198 
dmg_read_chunk(BDRVDMGState * s,int sector_num)199 static inline int dmg_read_chunk(BDRVDMGState *s,int sector_num)
200 {
201     if(!is_sector_in_chunk(s,s->current_chunk,sector_num)) {
202 	int ret;
203 	uint32_t chunk = search_chunk(s,sector_num);
204 
205 	if(chunk>=s->n_chunks)
206 	    return -1;
207 
208 	s->current_chunk = s->n_chunks;
209 	switch(s->types[chunk]) {
210 	case 0x80000005: { /* zlib compressed */
211 	    int i;
212 
213 	    ret = lseek(s->fd, s->offsets[chunk], SEEK_SET);
214 	    if(ret<0)
215 		return -1;
216 
217 	    /* we need to buffer, because only the chunk as whole can be
218 	     * inflated. */
219 	    i=0;
220 	    do {
221 		ret = read(s->fd, s->compressed_chunk+i, s->lengths[chunk]-i);
222 		if(ret<0 && errno==EINTR)
223 		    ret=0;
224 		i+=ret;
225 	    } while(ret>=0 && ret+i<s->lengths[chunk]);
226 
227 	    if (ret != s->lengths[chunk])
228 		return -1;
229 
230 	    s->zstream.next_in = s->compressed_chunk;
231 	    s->zstream.avail_in = s->lengths[chunk];
232 	    s->zstream.next_out = s->uncompressed_chunk;
233 	    s->zstream.avail_out = 512*s->sectorcounts[chunk];
234 	    ret = inflateReset(&s->zstream);
235 	    if(ret != Z_OK)
236 		return -1;
237 	    ret = inflate(&s->zstream, Z_FINISH);
238 	    if(ret != Z_STREAM_END || s->zstream.total_out != 512*s->sectorcounts[chunk])
239 		return -1;
240 	    break; }
241 	case 1: /* copy */
242 	    ret = read(s->fd, s->uncompressed_chunk, s->lengths[chunk]);
243 	    if (ret != s->lengths[chunk])
244 		return -1;
245 	    break;
246 	case 2: /* zero */
247 	    memset(s->uncompressed_chunk, 0, 512*s->sectorcounts[chunk]);
248 	    break;
249 	}
250 	s->current_chunk = chunk;
251     }
252     return 0;
253 }
254 
dmg_read(BlockDriverState * bs,int64_t sector_num,uint8_t * buf,int nb_sectors)255 static int dmg_read(BlockDriverState *bs, int64_t sector_num,
256                     uint8_t *buf, int nb_sectors)
257 {
258     BDRVDMGState *s = bs->opaque;
259     int i;
260 
261     for(i=0;i<nb_sectors;i++) {
262 	uint32_t sector_offset_in_chunk;
263 	if(dmg_read_chunk(s, sector_num+i) != 0)
264 	    return -1;
265 	sector_offset_in_chunk = sector_num+i-s->sectors[s->current_chunk];
266 	memcpy(buf+i*512,s->uncompressed_chunk+sector_offset_in_chunk*512,512);
267     }
268     return 0;
269 }
270 
dmg_close(BlockDriverState * bs)271 static void dmg_close(BlockDriverState *bs)
272 {
273     BDRVDMGState *s = bs->opaque;
274     close(s->fd);
275     if(s->n_chunks>0) {
276 	free(s->types);
277 	free(s->offsets);
278 	free(s->lengths);
279 	free(s->sectors);
280 	free(s->sectorcounts);
281     }
282     free(s->compressed_chunk);
283     free(s->uncompressed_chunk);
284     inflateEnd(&s->zstream);
285 }
286 
287 static BlockDriver bdrv_dmg = {
288     .format_name	= "dmg",
289     .instance_size	= sizeof(BDRVDMGState),
290     .bdrv_probe		= dmg_probe,
291     .bdrv_open		= dmg_open,
292     .bdrv_read		= dmg_read,
293     .bdrv_close		= dmg_close,
294 };
295 
bdrv_dmg_init(void)296 static void bdrv_dmg_init(void)
297 {
298     bdrv_register(&bdrv_dmg);
299 }
300 
301 block_init(bdrv_dmg_init);
302