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     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);