File:  [Qemu by Fabrice Bellard] / qemu / block-bochs.c
Revision 1.1: download - view: text, annotated - select for diffs
Tue Apr 24 16:37:52 2018 UTC (18 months, 2 weeks ago) by root
CVS tags: MAIN, HEAD
Initial revision

    1: /*
    2:  * Block driver for the various disk image formats used by Bochs
    3:  * Currently only for "growing" type in read-only mode
    4:  * 
    5:  * Copyright (c) 2005 Alex Beregszaszi
    6:  * 
    7:  * Permission is hereby granted, free of charge, to any person obtaining a copy
    8:  * of this software and associated documentation files (the "Software"), to deal
    9:  * in the Software without restriction, including without limitation the rights
   10:  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   11:  * copies of the Software, and to permit persons to whom the Software is
   12:  * furnished to do so, subject to the following conditions:
   13:  *
   14:  * The above copyright notice and this permission notice shall be included in
   15:  * all copies or substantial portions of the Software.
   16:  *
   17:  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   18:  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   19:  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
   20:  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   21:  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   22:  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   23:  * THE SOFTWARE.
   24:  */
   25: #include "vl.h"
   26: #include "block_int.h"
   27: 
   28: /**************************************************************/
   29: 
   30: #define HEADER_MAGIC "Bochs Virtual HD Image"
   31: #define HEADER_VERSION 0x00010000
   32: #define HEADER_SIZE 512
   33: 
   34: #define REDOLOG_TYPE "Redolog"
   35: #define GROWING_TYPE "Growing"
   36: 
   37: // not allocated: 0xffffffff
   38: 
   39: // always little-endian
   40: struct bochs_header {
   41:     char magic[32]; // "Bochs Virtual HD Image"
   42:     char type[16]; // "Redolog"
   43:     char subtype[16]; // "Undoable" / "Volatile" / "Growing"
   44:     uint32_t version;
   45:     uint32_t header; // size of header
   46:     
   47:     union {
   48: 	struct {
   49: 	    uint32_t catalog; // num of entries
   50: 	    uint32_t bitmap; // bitmap size
   51: 	    uint32_t extent; // extent size
   52: 	    uint64_t disk; // disk size
   53: 	    char padding[HEADER_SIZE - 64 - 8 - 20];
   54: 	} redolog;
   55: 	char padding[HEADER_SIZE - 64 - 8];
   56:     } extra;
   57: };
   58: 
   59: typedef struct BDRVBochsState {
   60:     int fd;
   61: 
   62:     uint32_t *catalog_bitmap;
   63:     int catalog_size;
   64:     
   65:     int data_offset;
   66:     
   67:     int bitmap_blocks;
   68:     int extent_blocks;
   69:     int extent_size;
   70: } BDRVBochsState;
   71: 
   72: static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
   73: {
   74:     const struct bochs_header *bochs = (const void *)buf;
   75:     
   76:     if (buf_size < HEADER_SIZE)
   77: 	return 0;
   78: 
   79:     if (!strcmp(bochs->magic, HEADER_MAGIC) &&
   80: 	!strcmp(bochs->type, REDOLOG_TYPE) &&
   81: 	!strcmp(bochs->subtype, GROWING_TYPE) &&
   82: 	(le32_to_cpu(bochs->version) == HEADER_VERSION))
   83: 	return 100;
   84: 
   85:     return 0;
   86: }
   87: 
   88: static int bochs_open(BlockDriverState *bs, const char *filename)
   89: {
   90:     BDRVBochsState *s = bs->opaque;
   91:     int fd, i;
   92:     struct bochs_header bochs;
   93: 
   94:     fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
   95:     if (fd < 0) {
   96:         fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
   97:         if (fd < 0)
   98:             return -1;
   99:     }
  100:     
  101:     bs->read_only = 1; // no write support yet
  102:     
  103:     s->fd = fd;
  104: 
  105:     if (read(fd, &bochs, sizeof(bochs)) != sizeof(bochs)) {
  106:         goto fail;
  107:     }
  108: 
  109:     if (strcmp(bochs.magic, HEADER_MAGIC) ||
  110:         strcmp(bochs.type, REDOLOG_TYPE) ||
  111:         strcmp(bochs.subtype, GROWING_TYPE) ||
  112: 	(le32_to_cpu(bochs.version) != HEADER_VERSION)) {
  113:         goto fail;
  114:     }
  115: 
  116:     bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
  117: 
  118:     lseek(s->fd, le32_to_cpu(bochs.header), SEEK_SET);
  119: 
  120:     s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog);
  121:     s->catalog_bitmap = qemu_malloc(s->catalog_size * 4);
  122:     if (!s->catalog_bitmap)
  123: 	goto fail;
  124:     if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) !=
  125: 	s->catalog_size * 4)
  126: 	goto fail;
  127:     for (i = 0; i < s->catalog_size; i++)
  128: 	le32_to_cpus(&s->catalog_bitmap[i]);
  129: 
  130:     s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
  131: 
  132:     s->bitmap_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.bitmap) - 1) / 512;
  133:     s->extent_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.extent) - 1) / 512;
  134:     
  135:     s->extent_size = le32_to_cpu(bochs.extra.redolog.extent);
  136: 
  137:     return 0;
  138:  fail:
  139:     close(fd);
  140:     return -1;
  141: }
  142: 
  143: static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
  144: {
  145:     BDRVBochsState *s = bs->opaque;
  146:     int64_t offset = sector_num * 512;
  147:     int64_t extent_index, extent_offset, bitmap_offset, block_offset;
  148:     char bitmap_entry;
  149: 
  150:     // seek to sector
  151:     extent_index = offset / s->extent_size;
  152:     extent_offset = (offset % s->extent_size) / 512;
  153:     
  154:     if (s->catalog_bitmap[extent_index] == 0xffffffff)
  155:     {
  156: //	fprintf(stderr, "page not allocated [%x - %x:%x]\n",
  157: //	    sector_num, extent_index, extent_offset);
  158: 	return -1; // not allocated
  159:     }
  160: 
  161:     bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] *
  162: 	(s->extent_blocks + s->bitmap_blocks));
  163:     block_offset = bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
  164:     
  165: //    fprintf(stderr, "sect: %x [ext i: %x o: %x] -> %x bitmap: %x block: %x\n",
  166: //	sector_num, extent_index, extent_offset,
  167: //	le32_to_cpu(s->catalog_bitmap[extent_index]),
  168: //	bitmap_offset, block_offset);
  169:     
  170:     // read in bitmap for current extent
  171:     lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET);
  172:     
  173:     read(s->fd, &bitmap_entry, 1);
  174:     
  175:     if (!((bitmap_entry >> (extent_offset % 8)) & 1))
  176:     {
  177: //	fprintf(stderr, "sector (%x) in bitmap not allocated\n",
  178: //	    sector_num);
  179: 	return -1; // not allocated
  180:     }
  181: 
  182:     lseek(s->fd, block_offset, SEEK_SET);
  183:     
  184:     return 0;
  185: }
  186: 
  187: static int bochs_read(BlockDriverState *bs, int64_t sector_num, 
  188:                     uint8_t *buf, int nb_sectors)
  189: {
  190:     BDRVBochsState *s = bs->opaque;
  191:     int ret;
  192: 
  193:     while (nb_sectors > 0) {
  194: 	if (!seek_to_sector(bs, sector_num))
  195: 	{
  196: 	    ret = read(s->fd, buf, 512);
  197: 	    if (ret != 512)
  198: 		return -1;
  199: 	}
  200: 	else
  201:             memset(buf, 0, 512);
  202:         nb_sectors--;
  203:         sector_num++;
  204:         buf += 512;
  205:     }
  206:     return 0;
  207: }
  208: 
  209: static void bochs_close(BlockDriverState *bs)
  210: {
  211:     BDRVBochsState *s = bs->opaque;
  212:     qemu_free(s->catalog_bitmap);
  213:     close(s->fd);
  214: }
  215: 
  216: BlockDriver bdrv_bochs = {
  217:     "bochs",
  218:     sizeof(BDRVBochsState),
  219:     bochs_probe,
  220:     bochs_open,
  221:     bochs_read,
  222:     NULL,
  223:     bochs_close,
  224: };

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