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