block/dmg.c

   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
  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
  61 static off_t read_off(int fd, int64_t offset)
  62 {
  63         uint64_t buffer;
  64         if (pread(fd, &buffer, 8, offset) < 8)
  65                 return 0;
  66         return be64_to_cpu(buffer);
  67 }
  68
  69 static off_t read_uint32(int fd, int64_t offset)
  70 {
  71         uint32_t buffer;
  72         if (pread(fd, &buffer, 4, offset) < 4)
  73                 return 0;
  74         return be32_to_cpu(buffer);
  75 }
  76
  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     int64_t offset;
  84
  85     s->fd = open(filename, O_RDONLY | O_BINARY);
  86     if (s->fd < 0)
  87         return -errno;
  88     bs->read_only = 1;
  89     s->n_chunks = 0;
  90     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
  91
  92     /* read offset of info blocks */
  93     offset = lseek(s->fd, -0x1d8, SEEK_END);
  94     if (offset < 0) {
  95         goto fail;
  96     }
  97
  98     info_begin = read_off(s->fd, offset);
  99     if (info_begin == 0) {
 100         goto fail;
 101     }
 102
 103     if (read_uint32(s->fd, info_begin) != 0x100) {
 104         goto fail;
 105     }
 106
 107     count = read_uint32(s->fd, info_begin + 4);
 108     if (count == 0) {
 109         goto fail;
 110     }
 111     info_end = info_begin + count;
 112
 113     offset = info_begin + 0x100;
 114
 115     /* read offsets */
 116     last_in_offset = last_out_offset = 0;
 117     while (offset < info_end) {
 118         uint32_t type;
 119
 120         count = read_uint32(s->fd, offset);
 121         if(count==0)
 122             goto fail;
 123         offset += 4;
 124
 125         type = read_uint32(s->fd, offset);
 126         if (type == 0x6d697368 && count >= 244) {
 127             int new_size, chunk_count;
 128
 129             offset += 4;
 130             offset += 200;
 131
 132             chunk_count = (count-204)/40;
 133             new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 134             s->types = qemu_realloc(s->types, new_size/2);
 135             s->offsets = qemu_realloc(s->offsets, new_size);
 136             s->lengths = qemu_realloc(s->lengths, new_size);
 137             s->sectors = qemu_realloc(s->sectors, new_size);
 138             s->sectorcounts = qemu_realloc(s->sectorcounts, new_size);
 139
 140             for(i=s->n_chunks;i<s->n_chunks+chunk_count;i++) {
 141                 s->types[i] = read_uint32(s->fd, offset);
 142                 offset += 4;
 143                 if(s->types[i]!=0x80000005 && s->types[i]!=1 && s->types[i]!=2) {
 144                     if(s->types[i]==0xffffffff) {
 145                         last_in_offset = s->offsets[i-1]+s->lengths[i-1];
 146                         last_out_offset = s->sectors[i-1]+s->sectorcounts[i-1];
 147                     }
 148                     chunk_count--;
 149                     i--;
 150                     offset += 36;
 151                     continue;
 152                 }
 153                 offset += 4;
 154
 155                 s->sectors[i] = last_out_offset+read_off(s->fd, offset);
 156                 offset += 8;
 157
 158                 s->sectorcounts[i] = read_off(s->fd, offset);
 159                 offset += 8;
 160
 161                 s->offsets[i] = last_in_offset+read_off(s->fd, offset);
 162                 offset += 8;
 163
 164                 s->lengths[i] = read_off(s->fd, offset);
 165                 offset += 8;
 166
 167                 if(s->lengths[i]>max_compressed_size)
 168                     max_compressed_size = s->lengths[i];
 169                 if(s->sectorcounts[i]>max_sectors_per_chunk)
 170                     max_sectors_per_chunk = s->sectorcounts[i];
 171             }
 172             s->n_chunks+=chunk_count;
 173         }
 174     }
 175
 176     /* initialize zlib engine */
 177     s->compressed_chunk = qemu_malloc(max_compressed_size+1);
 178     s->uncompressed_chunk = qemu_malloc(512*max_sectors_per_chunk);
 179     if(inflateInit(&s->zstream) != Z_OK)
 180         goto fail;
 181
 182     s->current_chunk = s->n_chunks;
 183
 184     return 0;
 185 fail:
 186     close(s->fd);
 187     return -1;
 188 }
 189
 190 static inline int is_sector_in_chunk(BDRVDMGState* s,
 191                 uint32_t chunk_num,int sector_num)
 192 {
 193     if(chunk_num>=s->n_chunks || s->sectors[chunk_num]>sector_num ||
 194             s->sectors[chunk_num]+s->sectorcounts[chunk_num]<=sector_num)
 195         return 0;
 196     else
 197         return -1;
 198 }
 199
 200 static inline uint32_t search_chunk(BDRVDMGState* s,int sector_num)
 201 {
 202     /* binary search */
 203     uint32_t chunk1=0,chunk2=s->n_chunks,chunk3;
 204     while(chunk1!=chunk2) {
 205         chunk3 = (chunk1+chunk2)/2;
 206         if(s->sectors[chunk3]>sector_num)
 207             chunk2 = chunk3;
 208         else if(s->sectors[chunk3]+s->sectorcounts[chunk3]>sector_num)
 209             return chunk3;
 210         else
 211             chunk1 = chunk3;
 212     }
 213     return s->n_chunks; /* error */
 214 }
 215
 216 static inline int dmg_read_chunk(BDRVDMGState *s,int sector_num)
 217 {
 218     if(!is_sector_in_chunk(s,s->current_chunk,sector_num)) {
 219         int ret;
 220         uint32_t chunk = search_chunk(s,sector_num);
 221
 222         if(chunk>=s->n_chunks)
 223             return -1;
 224
 225         s->current_chunk = s->n_chunks;
 226         switch(s->types[chunk]) {
 227         case 0x80000005: { /* zlib compressed */
 228             int i;
 229
 230             /* we need to buffer, because only the chunk as whole can be
 231              * inflated. */
 232             i=0;
 233             do {
 234                 ret = pread(s->fd, s->compressed_chunk+i, s->lengths[chunk]-i,
 235                             s->offsets[chunk] + i);
 236                 if(ret<0 && errno==EINTR)
 237                     ret=0;
 238                 i+=ret;
 239             } while(ret>=0 && ret+i<s->lengths[chunk]);
 240
 241             if (ret != s->lengths[chunk])
 242                 return -1;
 243
 244             s->zstream.next_in = s->compressed_chunk;
 245             s->zstream.avail_in = s->lengths[chunk];
 246             s->zstream.next_out = s->uncompressed_chunk;
 247             s->zstream.avail_out = 512*s->sectorcounts[chunk];
 248             ret = inflateReset(&s->zstream);
 249             if(ret != Z_OK)
 250                 return -1;
 251             ret = inflate(&s->zstream, Z_FINISH);
 252             if(ret != Z_STREAM_END || s->zstream.total_out != 512*s->sectorcounts[chunk])
 253                 return -1;
 254             break; }
 255         case 1: /* copy */
 256             ret = pread(s->fd, s->uncompressed_chunk, s->lengths[chunk],
 257                         s->offsets[chunk]);
 258             if (ret != s->lengths[chunk])
 259                 return -1;
 260             break;
 261         case 2: /* zero */
 262             memset(s->uncompressed_chunk, 0, 512*s->sectorcounts[chunk]);
 263             break;
 264         }
 265         s->current_chunk = chunk;
 266     }
 267     return 0;
 268 }
 269
 270 static int dmg_read(BlockDriverState *bs, int64_t sector_num,
 271                     uint8_t *buf, int nb_sectors)
 272 {
 273     BDRVDMGState *s = bs->opaque;
 274     int i;
 275
 276     for(i=0;i<nb_sectors;i++) {
 277         uint32_t sector_offset_in_chunk;
 278         if(dmg_read_chunk(s, sector_num+i) != 0)
 279             return -1;
 280         sector_offset_in_chunk = sector_num+i-s->sectors[s->current_chunk];
 281         memcpy(buf+i*512,s->uncompressed_chunk+sector_offset_in_chunk*512,512);
 282     }
 283     return 0;
 284 }
 285
 286 static void dmg_close(BlockDriverState *bs)
 287 {
 288     BDRVDMGState *s = bs->opaque;
 289     close(s->fd);
 290     if(s->n_chunks>0) {
 291         free(s->types);
 292         free(s->offsets);
 293         free(s->lengths);
 294         free(s->sectors);
 295         free(s->sectorcounts);
 296     }
 297     free(s->compressed_chunk);
 298     free(s->uncompressed_chunk);
 299     inflateEnd(&s->zstream);
 300 }
 301
 302 static BlockDriver bdrv_dmg = {
 303     .format_name        = "dmg",
 304     .instance_size      = sizeof(BDRVDMGState),
 305     .bdrv_probe         = dmg_probe,
 306     .bdrv_file_open     = dmg_open,
 307     .bdrv_read          = dmg_read,
 308     .bdrv_close         = dmg_close,
 309 };
 310
 311 static void bdrv_dmg_init(void)
 312 {
 313     bdrv_register(&bdrv_dmg);
 314 }
 315
 316 block_init(bdrv_dmg_init);