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)
  62 {
  63         uint64_t buffer;
  64         if(read(fd,&buffer,8)<8)
  65                 return 0;
  66         return be64_to_cpu(buffer);
  67 }
  68
  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
  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         goto fail;
  94     }
  95
  96     info_begin=read_off(s->fd);
  97     if(info_begin==0)
  98         goto fail;
  99     if(lseek(s->fd,info_begin,SEEK_SET)<0)
 100         goto fail;
 101     if(read_uint32(s->fd)!=0x100)
 102         goto fail;
 103     if((count = read_uint32(s->fd))==0)
 104         goto fail;
 105     info_end = info_begin+count;
 106     if(lseek(s->fd,0xf8,SEEK_CUR)<0)
 107         goto fail;
 108
 109     /* read offsets */
 110     last_in_offset = last_out_offset = 0;
 111     while(lseek(s->fd,0,SEEK_CUR)<info_end) {
 112         uint32_t type;
 113
 114         count = read_uint32(s->fd);
 115         if(count==0)
 116             goto fail;
 117         type = read_uint32(s->fd);
 118         if(type!=0x6d697368 || count<244)
 119             lseek(s->fd,count-4,SEEK_CUR);
 120         else {
 121             int new_size, chunk_count;
 122             if(lseek(s->fd,200,SEEK_CUR)<0)
 123                 goto fail;
 124             chunk_count = (count-204)/40;
 125             new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 126             s->types = qemu_realloc(s->types, new_size/2);
 127             s->offsets = qemu_realloc(s->offsets, new_size);
 128             s->lengths = qemu_realloc(s->lengths, new_size);
 129             s->sectors = qemu_realloc(s->sectors, new_size);
 130             s->sectorcounts = qemu_realloc(s->sectorcounts, new_size);
 131
 132             for(i=s->n_chunks;i<s->n_chunks+chunk_count;i++) {
 133                 s->types[i] = read_uint32(s->fd);
 134                 if(s->types[i]!=0x80000005 && s->types[i]!=1 && s->types[i]!=2) {
 135                     if(s->types[i]==0xffffffff) {
 136                         last_in_offset = s->offsets[i-1]+s->lengths[i-1];
 137                         last_out_offset = s->sectors[i-1]+s->sectorcounts[i-1];
 138                     }
 139                     chunk_count--;
 140                     i--;
 141                     if(lseek(s->fd,36,SEEK_CUR)<0)
 142                         goto fail;
 143                     continue;
 144                 }
 145                 read_uint32(s->fd);
 146                 s->sectors[i] = last_out_offset+read_off(s->fd);
 147                 s->sectorcounts[i] = read_off(s->fd);
 148                 s->offsets[i] = last_in_offset+read_off(s->fd);
 149                 s->lengths[i] = read_off(s->fd);
 150                 if(s->lengths[i]>max_compressed_size)
 151                     max_compressed_size = s->lengths[i];
 152                 if(s->sectorcounts[i]>max_sectors_per_chunk)
 153                     max_sectors_per_chunk = s->sectorcounts[i];
 154             }
 155             s->n_chunks+=chunk_count;
 156         }
 157     }
 158
 159     /* initialize zlib engine */
 160     s->compressed_chunk = qemu_malloc(max_compressed_size+1);
 161     s->uncompressed_chunk = qemu_malloc(512*max_sectors_per_chunk);
 162     if(inflateInit(&s->zstream) != Z_OK)
 163         goto fail;
 164
 165     s->current_chunk = s->n_chunks;
 166
 167     return 0;
 168 fail:
 169     close(s->fd);
 170     return -1;
 171 }
 172
 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
 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
 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
 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
 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
 296 static void bdrv_dmg_init(void)
 297 {
 298     bdrv_register(&bdrv_dmg);
 299 }
 300
 301 block_init(bdrv_dmg_init);