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 "vl.h"
  25 #include "block_int.h"
  26 #include "bswap.h"
  27 #include <zlib.h>
  28
  29 typedef struct BDRVDMGState {
  30     int fd;
  31
  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     char* compressed_chunk;
  48     char* 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(int fd)
  61 {
  62         uint64_t buffer;
  63         if(read(fd,&buffer,8)<8)
  64                 return 0;
  65         return be64_to_cpu(buffer);
  66 }
  67
  68 static off_t read_uint32(int fd)
  69 {
  70         uint32_t buffer;
  71         if(read(fd,&buffer,4)<4)
  72                 return 0;
  73         return be32_to_cpu(buffer);
  74 }
  75
  76 static int dmg_open(BlockDriverState *bs, const char *filename)
  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
  83     s->fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
  84     if (s->fd < 0)
  85         return -1;
  86     bs->read_only = 1;
  87     s->n_chunks = 0;
  88     s->offsets = s->lengths = s->sectors = s->sectorcounts = 0;
  89
  90     /* read offset of info blocks */
  91     if(lseek(s->fd,-0x1d8,SEEK_END)<0) {
  92 dmg_close:
  93         close(s->fd);
  94         return -1;
  95     }
  96     info_begin=read_off(s->fd);
  97     if(info_begin==0)
  98         goto dmg_close;
  99     if(lseek(s->fd,info_begin,SEEK_SET)<0)
 100         goto dmg_close;
 101     if(read_uint32(s->fd)!=0x100)
 102         goto dmg_close;
 103     if((count = read_uint32(s->fd))==0)
 104         goto dmg_close;
 105     info_end = info_begin+count;
 106     if(lseek(s->fd,0xf8,SEEK_CUR)<0)
 107         goto dmg_close;
 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 dmg_close;
 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 dmg_close;
 124             chunk_count = (count-204)/40;
 125             new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 126             s->types = realloc(s->types, new_size/2);
 127             s->offsets = realloc(s->offsets, new_size);
 128             s->lengths = realloc(s->lengths, new_size);
 129             s->sectors = realloc(s->sectors, new_size);
 130             s->sectorcounts = 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 dmg_close;
 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     if(!(s->compressed_chunk=(char*)malloc(max_compressed_size+1)))
 161         goto dmg_close;
 162     if(!(s->uncompressed_chunk=(char*)malloc(512*max_sectors_per_chunk)))
 163         goto dmg_close;
 164     if(inflateInit(&s->zstream) != Z_OK)
 165         goto dmg_close;
 166
 167     s->current_chunk = s->n_chunks;
 168
 169     return 0;
 170 }
 171
 172 static inline int is_sector_in_chunk(BDRVDMGState* s,
 173                 uint32_t chunk_num,int sector_num)
 174 {
 175     if(chunk_num>=s->n_chunks || s->sectors[chunk_num]>sector_num ||
 176             s->sectors[chunk_num]+s->sectorcounts[chunk_num]<=sector_num)
 177         return 0;
 178     else
 179         return -1;
 180 }
 181
 182 static inline uint32_t search_chunk(BDRVDMGState* s,int sector_num)
 183 {
 184     /* binary search */
 185     uint32_t chunk1=0,chunk2=s->n_chunks,chunk3;
 186     while(chunk1!=chunk2) {
 187         chunk3 = (chunk1+chunk2)/2;
 188         if(s->sectors[chunk3]>sector_num)
 189             chunk2 = chunk3;
 190         else if(s->sectors[chunk3]+s->sectorcounts[chunk3]>sector_num)
 191             return chunk3;
 192         else
 193             chunk1 = chunk3;
 194     }
 195     return s->n_chunks; /* error */
 196 }
 197
 198 static inline int dmg_read_chunk(BDRVDMGState *s,int sector_num)
 199 {
 200     if(!is_sector_in_chunk(s,s->current_chunk,sector_num)) {
 201         int ret;
 202         uint32_t chunk = search_chunk(s,sector_num);
 203
 204         if(chunk>=s->n_chunks)
 205             return -1;
 206
 207         s->current_chunk = s->n_chunks;
 208         switch(s->types[chunk]) {
 209         case 0x80000005: { /* zlib compressed */
 210             int i;
 211
 212             ret = lseek(s->fd, s->offsets[chunk], SEEK_SET);
 213             if(ret<0)
 214                 return -1;
 215
 216             /* we need to buffer, because only the chunk as whole can be
 217              * inflated. */
 218             i=0;
 219             do {
 220                 ret = read(s->fd, s->compressed_chunk+i, s->lengths[chunk]-i);
 221                 if(ret<0 && errno==EINTR)
 222                     ret=0;
 223                 i+=ret;
 224             } while(ret>=0 && ret+i<s->lengths[chunk]);
 225
 226             if (ret != s->lengths[chunk])
 227                 return -1;
 228
 229             s->zstream.next_in = s->compressed_chunk;
 230             s->zstream.avail_in = s->lengths[chunk];
 231             s->zstream.next_out = s->uncompressed_chunk;
 232             s->zstream.avail_out = 512*s->sectorcounts[chunk];
 233             ret = inflateReset(&s->zstream);
 234             if(ret != Z_OK)
 235                 return -1;
 236             ret = inflate(&s->zstream, Z_FINISH);
 237             if(ret != Z_STREAM_END || s->zstream.total_out != 512*s->sectorcounts[chunk])
 238                 return -1;
 239             break; }
 240         case 1: /* copy */
 241             ret = read(s->fd, s->uncompressed_chunk, s->lengths[chunk]);
 242             if (ret != s->lengths[chunk])
 243                 return -1;
 244             break;
 245         case 2: /* zero */
 246             memset(s->uncompressed_chunk, 0, 512*s->sectorcounts[chunk]);
 247             break;
 248         }
 249         s->current_chunk = chunk;
 250     }
 251     return 0;
 252 }
 253
 254 static int dmg_read(BlockDriverState *bs, int64_t sector_num,
 255                     uint8_t *buf, int nb_sectors)
 256 {
 257     BDRVDMGState *s = bs->opaque;
 258     int i;
 259
 260     for(i=0;i<nb_sectors;i++) {
 261         uint32_t sector_offset_in_chunk;
 262         if(dmg_read_chunk(s, sector_num+i) != 0)
 263             return -1;
 264         sector_offset_in_chunk = sector_num+i-s->sectors[s->current_chunk];
 265         memcpy(buf+i*512,s->uncompressed_chunk+sector_offset_in_chunk*512,512);
 266     }
 267     return 0;
 268 }
 269
 270 static void dmg_close(BlockDriverState *bs)
 271 {
 272     BDRVDMGState *s = bs->opaque;
 273     close(s->fd);
 274     if(s->n_chunks>0) {
 275         free(s->types);
 276         free(s->offsets);
 277         free(s->lengths);
 278         free(s->sectors);
 279         free(s->sectorcounts);
 280     }
 281     free(s->compressed_chunk);
 282     free(s->uncompressed_chunk);
 283     inflateEnd(&s->zstream);
 284 }
 285
 286 BlockDriver bdrv_dmg = {
 287     "dmg",
 288     sizeof(BDRVDMGState),
 289     dmg_probe,
 290     dmg_open,
 291     dmg_read,
 292     NULL,
 293     dmg_close,
 294 };
 295