block-vpc.c

   1 /*
   2  * Block driver for Conectix/Microsoft Virtual PC images
   3  *
   4  * Copyright (c) 2005 Alex Beregszaszi
   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
  27 /**************************************************************/
  28
  29 #define HEADER_SIZE 512
  30
  31 //#define CACHE
  32
  33 // always big-endian
  34 struct vpc_subheader {
  35     char magic[8]; // "conectix" / "cxsparse"
  36     union {
  37         struct {
  38             uint32_t unk1[2];
  39             uint32_t unk2; // always zero?
  40             uint32_t subheader_offset;
  41             uint32_t unk3; // some size?
  42             char creator[4]; // "vpc "
  43             uint16_t major;
  44             uint16_t minor;
  45             char guest[4]; // "Wi2k"
  46             uint32_t unk4[7];
  47             uint8_t vnet_id[16]; // virtual network id, purpose unknown
  48             // next 16 longs are used, but dunno the purpose
  49             // next 6 longs unknown, following 7 long maybe a serial
  50             char padding[HEADER_SIZE - 84];
  51         } main;
  52         struct {
  53             uint32_t unk1[2]; // all bits set
  54             uint32_t unk2; // always zero?
  55             uint32_t pagetable_offset;
  56             uint32_t unk3;
  57             uint32_t pagetable_entries; // 32bit/entry
  58             uint32_t pageentry_size; // 512*8*512
  59             uint32_t nb_sectors;
  60             char padding[HEADER_SIZE - 40];
  61         } sparse;
  62         char padding[HEADER_SIZE - 8];
  63     } type;
  64 };
  65
  66 typedef struct BDRVVPCState {
  67     int fd;
  68
  69     int pagetable_entries;
  70     uint32_t *pagetable;
  71
  72     uint32_t pageentry_size;
  73 #ifdef CACHE
  74     uint8_t *pageentry_u8;
  75     uint32_t *pageentry_u32;
  76     uint16_t *pageentry_u16;
  77
  78     uint64_t last_bitmap;
  79 #endif
  80 } BDRVVPCState;
  81
  82 static int vpc_probe(const uint8_t *buf, int buf_size, const char *filename)
  83 {
  84     if (buf_size >= 8 && !strncmp(buf, "conectix", 8))
  85         return 100;
  86     return 0;
  87 }
  88
  89 static int vpc_open(BlockDriverState *bs, const char *filename)
  90 {
  91     BDRVVPCState *s = bs->opaque;
  92     int fd, i;
  93     struct vpc_subheader header;
  94
  95     fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
  96     if (fd < 0) {
  97         fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
  98         if (fd < 0)
  99             return -1;
 100     }
 101
 102     bs->read_only = 1; // no write support yet
 103
 104     s->fd = fd;
 105
 106     if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)
 107         goto fail;
 108
 109     if (strncmp(header.magic, "conectix", 8))
 110         goto fail;
 111     lseek(s->fd, be32_to_cpu(header.type.main.subheader_offset), SEEK_SET);
 112
 113     if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)
 114         goto fail;
 115
 116     if (strncmp(header.magic, "cxsparse", 8))
 117         goto fail;
 118
 119     bs->total_sectors = ((uint64_t)be32_to_cpu(header.type.sparse.pagetable_entries) *
 120                         be32_to_cpu(header.type.sparse.pageentry_size)) / 512;
 121
 122     lseek(s->fd, be32_to_cpu(header.type.sparse.pagetable_offset), SEEK_SET);
 123
 124     s->pagetable_entries = be32_to_cpu(header.type.sparse.pagetable_entries);
 125     s->pagetable = qemu_malloc(s->pagetable_entries * 4);
 126     if (!s->pagetable)
 127         goto fail;
 128     if (read(s->fd, s->pagetable, s->pagetable_entries * 4) !=
 129         s->pagetable_entries * 4)
 130         goto fail;
 131     for (i = 0; i < s->pagetable_entries; i++)
 132         be32_to_cpus(&s->pagetable[i]);
 133
 134     s->pageentry_size = be32_to_cpu(header.type.sparse.pageentry_size);
 135 #ifdef CACHE
 136     s->pageentry_u8 = qemu_malloc(512);
 137     if (!s->pageentry_u8)
 138         goto fail;
 139     s->pageentry_u32 = s->pageentry_u8;
 140     s->pageentry_u16 = s->pageentry_u8;
 141     s->last_pagetable = -1;
 142 #endif
 143
 144     return 0;
 145  fail:
 146     close(fd);
 147     return -1;
 148 }
 149
 150 static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
 151 {
 152     BDRVVPCState *s = bs->opaque;
 153     uint64_t offset = sector_num * 512;
 154     uint64_t bitmap_offset, block_offset;
 155     uint32_t pagetable_index, pageentry_index;
 156
 157     pagetable_index = offset / s->pageentry_size;
 158     pageentry_index = (offset % s->pageentry_size) / 512;
 159
 160     if (pagetable_index > s->pagetable_entries || s->pagetable[pagetable_index] == 0xffffffff)
 161         return -1; // not allocated
 162
 163     bitmap_offset = 512 * s->pagetable[pagetable_index];
 164     block_offset = bitmap_offset + 512 + (512 * pageentry_index);
 165
 166 //    printf("sector: %llx, index: %x, offset: %x, bioff: %llx, bloff: %llx\n",
 167 //      sector_num, pagetable_index, pageentry_index,
 168 //      bitmap_offset, block_offset);
 169
 170 // disabled by reason
 171 #if 0
 172 #ifdef CACHE
 173     if (bitmap_offset != s->last_bitmap)
 174     {
 175         lseek(s->fd, bitmap_offset, SEEK_SET);
 176
 177         s->last_bitmap = bitmap_offset;
 178
 179         // Scary! Bitmap is stored as big endian 32bit entries,
 180         // while we used to look it up byte by byte
 181         read(s->fd, s->pageentry_u8, 512);
 182         for (i = 0; i < 128; i++)
 183             be32_to_cpus(&s->pageentry_u32[i]);
 184     }
 185
 186     if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
 187         return -1;
 188 #else
 189     lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);
 190
 191     read(s->fd, &bitmap_entry, 1);
 192
 193     if ((bitmap_entry >> (pageentry_index % 8)) & 1)
 194         return -1; // not allocated
 195 #endif
 196 #endif
 197     lseek(s->fd, block_offset, SEEK_SET);
 198
 199     return 0;
 200 }
 201
 202 static int vpc_read(BlockDriverState *bs, int64_t sector_num,
 203                     uint8_t *buf, int nb_sectors)
 204 {
 205     BDRVVPCState *s = bs->opaque;
 206     int ret;
 207
 208     while (nb_sectors > 0) {
 209         if (!seek_to_sector(bs, sector_num))
 210         {
 211             ret = read(s->fd, buf, 512);
 212             if (ret != 512)
 213                 return -1;
 214         }
 215         else
 216             memset(buf, 0, 512);
 217         nb_sectors--;
 218         sector_num++;
 219         buf += 512;
 220     }
 221     return 0;
 222 }
 223
 224 static void vpc_close(BlockDriverState *bs)
 225 {
 226     BDRVVPCState *s = bs->opaque;
 227     qemu_free(s->pagetable);
 228 #ifdef CACHE
 229     qemu_free(s->pageentry_u8);
 230 #endif
 231     close(s->fd);
 232 }
 233
 234 BlockDriver bdrv_vpc = {
 235     "vpc",
 236     sizeof(BDRVVPCState),
 237     vpc_probe,
 238     vpc_open,
 239     vpc_read,
 240     NULL,
 241     vpc_close,
 242 };