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 "qemu-common.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((char *)buf, "conectix", 8))
  85         return 100;
  86     return 0;
  87 }
  88
  89 static int vpc_open(BlockDriverState *bs, const char *filename, int flags)
  90 {
  91     BDRVVPCState *s = bs->opaque;
  92     int fd, i;
  93     struct vpc_subheader header;
  94
  95     fd = open(filename, O_RDONLY | O_BINARY);
  96     if (fd < 0)
  97         return -1;
  98
  99     bs->read_only = 1; // no write support yet
 100
 101     s->fd = fd;
 102
 103     if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)
 104         goto fail;
 105
 106     if (strncmp(header.magic, "conectix", 8))
 107         goto fail;
 108     lseek(s->fd, be32_to_cpu(header.type.main.subheader_offset), SEEK_SET);
 109
 110     if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)
 111         goto fail;
 112
 113     if (strncmp(header.magic, "cxsparse", 8))
 114         goto fail;
 115
 116     bs->total_sectors = ((uint64_t)be32_to_cpu(header.type.sparse.pagetable_entries) *
 117                         be32_to_cpu(header.type.sparse.pageentry_size)) / 512;
 118
 119     lseek(s->fd, be32_to_cpu(header.type.sparse.pagetable_offset), SEEK_SET);
 120
 121     s->pagetable_entries = be32_to_cpu(header.type.sparse.pagetable_entries);
 122     s->pagetable = qemu_malloc(s->pagetable_entries * 4);
 123     if (!s->pagetable)
 124         goto fail;
 125     if (read(s->fd, s->pagetable, s->pagetable_entries * 4) !=
 126         s->pagetable_entries * 4)
 127         goto fail;
 128     for (i = 0; i < s->pagetable_entries; i++)
 129         be32_to_cpus(&s->pagetable[i]);
 130
 131     s->pageentry_size = be32_to_cpu(header.type.sparse.pageentry_size);
 132 #ifdef CACHE
 133     s->pageentry_u8 = qemu_malloc(512);
 134     if (!s->pageentry_u8)
 135         goto fail;
 136     s->pageentry_u32 = s->pageentry_u8;
 137     s->pageentry_u16 = s->pageentry_u8;
 138     s->last_pagetable = -1;
 139 #endif
 140
 141     return 0;
 142  fail:
 143     close(fd);
 144     return -1;
 145 }
 146
 147 static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
 148 {
 149     BDRVVPCState *s = bs->opaque;
 150     uint64_t offset = sector_num * 512;
 151     uint64_t bitmap_offset, block_offset;
 152     uint32_t pagetable_index, pageentry_index;
 153
 154     pagetable_index = offset / s->pageentry_size;
 155     pageentry_index = (offset % s->pageentry_size) / 512;
 156
 157     if (pagetable_index > s->pagetable_entries || s->pagetable[pagetable_index] == 0xffffffff)
 158         return -1; // not allocated
 159
 160     bitmap_offset = 512 * s->pagetable[pagetable_index];
 161     block_offset = bitmap_offset + 512 + (512 * pageentry_index);
 162
 163 //    printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\n",
 164 //      sector_num, pagetable_index, pageentry_index,
 165 //      bitmap_offset, block_offset);
 166
 167 // disabled by reason
 168 #if 0
 169 #ifdef CACHE
 170     if (bitmap_offset != s->last_bitmap)
 171     {
 172         lseek(s->fd, bitmap_offset, SEEK_SET);
 173
 174         s->last_bitmap = bitmap_offset;
 175
 176         // Scary! Bitmap is stored as big endian 32bit entries,
 177         // while we used to look it up byte by byte
 178         read(s->fd, s->pageentry_u8, 512);
 179         for (i = 0; i < 128; i++)
 180             be32_to_cpus(&s->pageentry_u32[i]);
 181     }
 182
 183     if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
 184         return -1;
 185 #else
 186     lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);
 187
 188     read(s->fd, &bitmap_entry, 1);
 189
 190     if ((bitmap_entry >> (pageentry_index % 8)) & 1)
 191         return -1; // not allocated
 192 #endif
 193 #endif
 194     lseek(s->fd, block_offset, SEEK_SET);
 195
 196     return 0;
 197 }
 198
 199 static int vpc_read(BlockDriverState *bs, int64_t sector_num,
 200                     uint8_t *buf, int nb_sectors)
 201 {
 202     BDRVVPCState *s = bs->opaque;
 203     int ret;
 204
 205     while (nb_sectors > 0) {
 206         if (!seek_to_sector(bs, sector_num))
 207         {
 208             ret = read(s->fd, buf, 512);
 209             if (ret != 512)
 210                 return -1;
 211         }
 212         else
 213             memset(buf, 0, 512);
 214         nb_sectors--;
 215         sector_num++;
 216         buf += 512;
 217     }
 218     return 0;
 219 }
 220
 221 static void vpc_close(BlockDriverState *bs)
 222 {
 223     BDRVVPCState *s = bs->opaque;
 224     qemu_free(s->pagetable);
 225 #ifdef CACHE
 226     qemu_free(s->pageentry_u8);
 227 #endif
 228     close(s->fd);
 229 }
 230
 231 BlockDriver bdrv_vpc = {
 232     "vpc",
 233     sizeof(BDRVVPCState),
 234     vpc_probe,
 235     vpc_open,
 236     vpc_read,
 237     NULL,
 238     vpc_close,
 239 };