File:  [Qemu by Fabrice Bellard] / qemu / block-bochs.c
Revision 1.1.1.3 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 16:47:31 2018 UTC (18 months, 2 weeks ago) by root
Branches: qemu, MAIN
CVS tags: qemu0091, HEAD
qemu 0.9.1

    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 "qemu-common.h"
   26: #include "block_int.h"
   27: 
   28: /**************************************************************/
   29: 
   30: #define HEADER_MAGIC "Bochs Virtual HD Image"
   31: #define HEADER_VERSION 0x00020000
   32: #define HEADER_V1 0x00010000
   33: #define HEADER_SIZE 512
   34: 
   35: #define REDOLOG_TYPE "Redolog"
   36: #define GROWING_TYPE "Growing"
   37: 
   38: // not allocated: 0xffffffff
   39: 
   40: // always little-endian
   41: struct bochs_header_v1 {
   42:     char magic[32]; // "Bochs Virtual HD Image"
   43:     char type[16]; // "Redolog"
   44:     char subtype[16]; // "Undoable" / "Volatile" / "Growing"
   45:     uint32_t version;
   46:     uint32_t header; // size of header
   47: 
   48:     union {
   49: 	struct {
   50: 	    uint32_t catalog; // num of entries
   51: 	    uint32_t bitmap; // bitmap size
   52: 	    uint32_t extent; // extent size
   53: 	    uint64_t disk; // disk size
   54: 	    char padding[HEADER_SIZE - 64 - 8 - 20];
   55: 	} redolog;
   56: 	char padding[HEADER_SIZE - 64 - 8];
   57:     } extra;
   58: };
   59: 
   60: // always little-endian
   61: struct bochs_header {
   62:     char magic[32]; // "Bochs Virtual HD Image"
   63:     char type[16]; // "Redolog"
   64:     char subtype[16]; // "Undoable" / "Volatile" / "Growing"
   65:     uint32_t version;
   66:     uint32_t header; // size of header
   67: 
   68:     union {
   69: 	struct {
   70: 	    uint32_t catalog; // num of entries
   71: 	    uint32_t bitmap; // bitmap size
   72: 	    uint32_t extent; // extent size
   73: 	    uint32_t reserved; // for ???
   74: 	    uint64_t disk; // disk size
   75: 	    char padding[HEADER_SIZE - 64 - 8 - 24];
   76: 	} redolog;
   77: 	char padding[HEADER_SIZE - 64 - 8];
   78:     } extra;
   79: };
   80: 
   81: typedef struct BDRVBochsState {
   82:     int fd;
   83: 
   84:     uint32_t *catalog_bitmap;
   85:     int catalog_size;
   86: 
   87:     int data_offset;
   88: 
   89:     int bitmap_blocks;
   90:     int extent_blocks;
   91:     int extent_size;
   92: } BDRVBochsState;
   93: 
   94: static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
   95: {
   96:     const struct bochs_header *bochs = (const void *)buf;
   97: 
   98:     if (buf_size < HEADER_SIZE)
   99: 	return 0;
  100: 
  101:     if (!strcmp(bochs->magic, HEADER_MAGIC) &&
  102: 	!strcmp(bochs->type, REDOLOG_TYPE) &&
  103: 	!strcmp(bochs->subtype, GROWING_TYPE) &&
  104: 	((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
  105: 	(le32_to_cpu(bochs->version) == HEADER_V1)))
  106: 	return 100;
  107: 
  108:     return 0;
  109: }
  110: 
  111: static int bochs_open(BlockDriverState *bs, const char *filename, int flags)
  112: {
  113:     BDRVBochsState *s = bs->opaque;
  114:     int fd, i;
  115:     struct bochs_header bochs;
  116:     struct bochs_header_v1 header_v1;
  117: 
  118:     fd = open(filename, O_RDWR | O_BINARY);
  119:     if (fd < 0) {
  120:         fd = open(filename, O_RDONLY | O_BINARY);
  121:         if (fd < 0)
  122:             return -1;
  123:     }
  124: 
  125:     bs->read_only = 1; // no write support yet
  126: 
  127:     s->fd = fd;
  128: 
  129:     if (read(fd, &bochs, sizeof(bochs)) != sizeof(bochs)) {
  130:         goto fail;
  131:     }
  132: 
  133:     if (strcmp(bochs.magic, HEADER_MAGIC) ||
  134:         strcmp(bochs.type, REDOLOG_TYPE) ||
  135:         strcmp(bochs.subtype, GROWING_TYPE) ||
  136: 	((le32_to_cpu(bochs.version) != HEADER_VERSION) &&
  137: 	(le32_to_cpu(bochs.version) != HEADER_V1))) {
  138:         goto fail;
  139:     }
  140: 
  141:     if (le32_to_cpu(bochs.version) == HEADER_V1) {
  142:       memcpy(&header_v1, &bochs, sizeof(bochs));
  143:       bs->total_sectors = le64_to_cpu(header_v1.extra.redolog.disk) / 512;
  144:     } else {
  145:       bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
  146:     }
  147: 
  148:     lseek(s->fd, le32_to_cpu(bochs.header), SEEK_SET);
  149: 
  150:     s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog);
  151:     s->catalog_bitmap = qemu_malloc(s->catalog_size * 4);
  152:     if (!s->catalog_bitmap)
  153: 	goto fail;
  154:     if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) !=
  155: 	s->catalog_size * 4)
  156: 	goto fail;
  157:     for (i = 0; i < s->catalog_size; i++)
  158: 	le32_to_cpus(&s->catalog_bitmap[i]);
  159: 
  160:     s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
  161: 
  162:     s->bitmap_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.bitmap) - 1) / 512;
  163:     s->extent_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.extent) - 1) / 512;
  164: 
  165:     s->extent_size = le32_to_cpu(bochs.extra.redolog.extent);
  166: 
  167:     return 0;
  168:  fail:
  169:     close(fd);
  170:     return -1;
  171: }
  172: 
  173: static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
  174: {
  175:     BDRVBochsState *s = bs->opaque;
  176:     int64_t offset = sector_num * 512;
  177:     int64_t extent_index, extent_offset, bitmap_offset, block_offset;
  178:     char bitmap_entry;
  179: 
  180:     // seek to sector
  181:     extent_index = offset / s->extent_size;
  182:     extent_offset = (offset % s->extent_size) / 512;
  183: 
  184:     if (s->catalog_bitmap[extent_index] == 0xffffffff)
  185:     {
  186: //	fprintf(stderr, "page not allocated [%x - %x:%x]\n",
  187: //	    sector_num, extent_index, extent_offset);
  188: 	return -1; // not allocated
  189:     }
  190: 
  191:     bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] *
  192: 	(s->extent_blocks + s->bitmap_blocks));
  193:     block_offset = bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
  194: 
  195: //    fprintf(stderr, "sect: %x [ext i: %x o: %x] -> %x bitmap: %x block: %x\n",
  196: //	sector_num, extent_index, extent_offset,
  197: //	le32_to_cpu(s->catalog_bitmap[extent_index]),
  198: //	bitmap_offset, block_offset);
  199: 
  200:     // read in bitmap for current extent
  201:     lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET);
  202: 
  203:     read(s->fd, &bitmap_entry, 1);
  204: 
  205:     if (!((bitmap_entry >> (extent_offset % 8)) & 1))
  206:     {
  207: //	fprintf(stderr, "sector (%x) in bitmap not allocated\n",
  208: //	    sector_num);
  209: 	return -1; // not allocated
  210:     }
  211: 
  212:     lseek(s->fd, block_offset, SEEK_SET);
  213: 
  214:     return 0;
  215: }
  216: 
  217: static int bochs_read(BlockDriverState *bs, int64_t sector_num,
  218:                     uint8_t *buf, int nb_sectors)
  219: {
  220:     BDRVBochsState *s = bs->opaque;
  221:     int ret;
  222: 
  223:     while (nb_sectors > 0) {
  224: 	if (!seek_to_sector(bs, sector_num))
  225: 	{
  226: 	    ret = read(s->fd, buf, 512);
  227: 	    if (ret != 512)
  228: 		return -1;
  229: 	}
  230: 	else
  231:             memset(buf, 0, 512);
  232:         nb_sectors--;
  233:         sector_num++;
  234:         buf += 512;
  235:     }
  236:     return 0;
  237: }
  238: 
  239: static void bochs_close(BlockDriverState *bs)
  240: {
  241:     BDRVBochsState *s = bs->opaque;
  242:     qemu_free(s->catalog_bitmap);
  243:     close(s->fd);
  244: }
  245: 
  246: BlockDriver bdrv_bochs = {
  247:     "bochs",
  248:     sizeof(BDRVBochsState),
  249:     bochs_probe,
  250:     bochs_open,
  251:     bochs_read,
  252:     NULL,
  253:     bochs_close,
  254: };

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