block/dmg.c - qemu - Git at Google

 /*
  * QEMU Block driver for DMG images
  *
  * Copyright (c) 2004 Johannes E. Schindelin
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
 #include "qemu-common.h"
 #include "block/block_int.h"
 #include "qemu/bswap.h"
 #include "qemu/module.h"
 #include <zlib.h>

 typedef struct BDRVDMGState {
     CoMutex lock;
     /* each chunk contains a certain number of sectors,
      * offsets[i] is the offset in the .dmg file,
      * lengths[i] is the length of the compressed chunk,
      * sectors[i] is the sector beginning at offsets[i],
      * sectorcounts[i] is the number of sectors in that chunk,
      * the sectors array is ordered
      * 0<=i<n_chunks */

     uint32_t n_chunks;
     uint32_t* types;
     uint64_t* offsets;
     uint64_t* lengths;
     uint64_t* sectors;
     uint64_t* sectorcounts;
     uint32_t current_chunk;
     uint8_t *compressed_chunk;
     uint8_t *uncompressed_chunk;
     z_stream zstream;
 } BDRVDMGState;

 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
 {
     int len;

     if (!filename) {
         return 0;
     }

     len = strlen(filename);
     if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
         return 2;
     }
     return 0;
 }

 static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
 {
     uint64_t buffer;
     int ret;

     ret = bdrv_pread(bs->file, offset, &buffer, 8);
     if (ret < 0) {
         return ret;
     }

     *result = be64_to_cpu(buffer);
     return 0;
 }

 static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
 {
     uint32_t buffer;
     int ret;

     ret = bdrv_pread(bs->file, offset, &buffer, 4);
     if (ret < 0) {
         return ret;
     }

     *result = be32_to_cpu(buffer);
     return 0;
 }

 static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
                     Error **errp)
 {
     BDRVDMGState *s = bs->opaque;
     uint64_t info_begin,info_end,last_in_offset,last_out_offset;
     uint32_t count, tmp;
     uint32_t max_compressed_size=1,max_sectors_per_chunk=1,i;
     int64_t offset;
     int ret;

     bs->read_only = 1;
     s->n_chunks = 0;
     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;

     /* read offset of info blocks */
     offset = bdrv_getlength(bs->file);
     if (offset < 0) {
         ret = offset;
         goto fail;
     }
     offset -= 0x1d8;

     ret = read_uint64(bs, offset, &info_begin);
     if (ret < 0) {
         goto fail;
     } else if (info_begin == 0) {
         ret = -EINVAL;
         goto fail;
     }

     ret = read_uint32(bs, info_begin, &tmp);
     if (ret < 0) {
         goto fail;
     } else if (tmp != 0x100) {
         ret = -EINVAL;
         goto fail;
     }

     ret = read_uint32(bs, info_begin + 4, &count);
     if (ret < 0) {
         goto fail;
     } else if (count == 0) {
         ret = -EINVAL;
         goto fail;
     }
     info_end = info_begin + count;

     offset = info_begin + 0x100;

     /* read offsets */
     last_in_offset = last_out_offset = 0;
     while (offset < info_end) {
         uint32_t type;

         ret = read_uint32(bs, offset, &count);
         if (ret < 0) {
             goto fail;
         } else if (count == 0) {
             ret = -EINVAL;
             goto fail;
         }
         offset += 4;

         ret = read_uint32(bs, offset, &type);
         if (ret < 0) {
             goto fail;
         }

 	if (type == 0x6d697368 && count >= 244) {
 	    int new_size, chunk_count;

             offset += 4;
             offset += 200;

 	    chunk_count = (count-204)/40;
 	    new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
 	    s->types = g_realloc(s->types, new_size/2);
 	    s->offsets = g_realloc(s->offsets, new_size);
 	    s->lengths = g_realloc(s->lengths, new_size);
 	    s->sectors = g_realloc(s->sectors, new_size);
 	    s->sectorcounts = g_realloc(s->sectorcounts, new_size);

             for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
                 ret = read_uint32(bs, offset, &s->types[i]);
                 if (ret < 0) {
                     goto fail;
                 }
 		offset += 4;
 		if(s->types[i]!=0x80000005 && s->types[i]!=1 && s->types[i]!=2) {
 		    if(s->types[i]==0xffffffff) {
 			last_in_offset = s->offsets[i-1]+s->lengths[i-1];
 			last_out_offset = s->sectors[i-1]+s->sectorcounts[i-1];
 		    }
 		    chunk_count--;
 		    i--;
 		    offset += 36;
 		    continue;
 		}
 		offset += 4;

                 ret = read_uint64(bs, offset, &s->sectors[i]);
                 if (ret < 0) {
                     goto fail;
                 }
                 s->sectors[i] += last_out_offset;
                 offset += 8;

                 ret = read_uint64(bs, offset, &s->sectorcounts[i]);
                 if (ret < 0) {
                     goto fail;
                 }
                 offset += 8;

                 ret = read_uint64(bs, offset, &s->offsets[i]);
                 if (ret < 0) {
                     goto fail;
                 }
                 s->offsets[i] += last_in_offset;
                 offset += 8;

                 ret = read_uint64(bs, offset, &s->lengths[i]);
                 if (ret < 0) {
                     goto fail;
                 }
                 offset += 8;

 		if(s->lengths[i]>max_compressed_size)
 		    max_compressed_size = s->lengths[i];
 		if(s->sectorcounts[i]>max_sectors_per_chunk)
 		    max_sectors_per_chunk = s->sectorcounts[i];
 	    }
 	    s->n_chunks+=chunk_count;
 	}
     }

     /* initialize zlib engine */
     s->compressed_chunk = g_malloc(max_compressed_size+1);
     s->uncompressed_chunk = g_malloc(512*max_sectors_per_chunk);
     if(inflateInit(&s->zstream) != Z_OK) {
         ret = -EINVAL;
         goto fail;
     }

     s->current_chunk = s->n_chunks;

     qemu_co_mutex_init(&s->lock);
     return 0;

 fail:
     g_free(s->types);
     g_free(s->offsets);
     g_free(s->lengths);
     g_free(s->sectors);
     g_free(s->sectorcounts);
     g_free(s->compressed_chunk);
     g_free(s->uncompressed_chunk);
     return ret;
 }

 static inline int is_sector_in_chunk(BDRVDMGState* s,
 		uint32_t chunk_num,int sector_num)
 {
     if(chunk_num>=s->n_chunks || s->sectors[chunk_num]>sector_num ||
 	    s->sectors[chunk_num]+s->sectorcounts[chunk_num]<=sector_num)
 	return 0;
     else
 	return -1;
 }

 static inline uint32_t search_chunk(BDRVDMGState* s,int sector_num)
 {
     /* binary search */
     uint32_t chunk1=0,chunk2=s->n_chunks,chunk3;
     while(chunk1!=chunk2) {
 	chunk3 = (chunk1+chunk2)/2;
 	if(s->sectors[chunk3]>sector_num)
 	    chunk2 = chunk3;
 	else if(s->sectors[chunk3]+s->sectorcounts[chunk3]>sector_num)
 	    return chunk3;
 	else
 	    chunk1 = chunk3;
     }
     return s->n_chunks; /* error */
 }

 static inline int dmg_read_chunk(BlockDriverState *bs, int sector_num)
 {
     BDRVDMGState *s = bs->opaque;

     if(!is_sector_in_chunk(s,s->current_chunk,sector_num)) {
 	int ret;
 	uint32_t chunk = search_chunk(s,sector_num);

 	if(chunk>=s->n_chunks)
 	    return -1;

 	s->current_chunk = s->n_chunks;
 	switch(s->types[chunk]) {
 	case 0x80000005: { /* zlib compressed */
 	    int i;

 	    /* we need to buffer, because only the chunk as whole can be
 	     * inflated. */
 	    i=0;
 	    do {
                 ret = bdrv_pread(bs->file, s->offsets[chunk] + i,
                                  s->compressed_chunk+i, s->lengths[chunk]-i);
 		if(ret<0 && errno==EINTR)
 		    ret=0;
 		i+=ret;
 	    } while(ret>=0 && ret+i<s->lengths[chunk]);

 	    if (ret != s->lengths[chunk])
 		return -1;

 	    s->zstream.next_in = s->compressed_chunk;
 	    s->zstream.avail_in = s->lengths[chunk];
 	    s->zstream.next_out = s->uncompressed_chunk;
 	    s->zstream.avail_out = 512*s->sectorcounts[chunk];
 	    ret = inflateReset(&s->zstream);
 	    if(ret != Z_OK)
 		return -1;
 	    ret = inflate(&s->zstream, Z_FINISH);
 	    if(ret != Z_STREAM_END || s->zstream.total_out != 512*s->sectorcounts[chunk])
 		return -1;
 	    break; }
 	case 1: /* copy */
 	    ret = bdrv_pread(bs->file, s->offsets[chunk],
                              s->uncompressed_chunk, s->lengths[chunk]);
 	    if (ret != s->lengths[chunk])
 		return -1;
 	    break;
 	case 2: /* zero */
 	    memset(s->uncompressed_chunk, 0, 512*s->sectorcounts[chunk]);
 	    break;
 	}
 	s->current_chunk = chunk;
     }
     return 0;
 }

 static int dmg_read(BlockDriverState *bs, int64_t sector_num,
                     uint8_t *buf, int nb_sectors)
 {
     BDRVDMGState *s = bs->opaque;
     int i;

     for(i=0;i<nb_sectors;i++) {
 	uint32_t sector_offset_in_chunk;
 	if(dmg_read_chunk(bs, sector_num+i) != 0)
 	    return -1;
 	sector_offset_in_chunk = sector_num+i-s->sectors[s->current_chunk];
 	memcpy(buf+i*512,s->uncompressed_chunk+sector_offset_in_chunk*512,512);
     }
     return 0;
 }

 static coroutine_fn int dmg_co_read(BlockDriverState *bs, int64_t sector_num,
                                     uint8_t *buf, int nb_sectors)
 {
     int ret;
     BDRVDMGState *s = bs->opaque;
     qemu_co_mutex_lock(&s->lock);
     ret = dmg_read(bs, sector_num, buf, nb_sectors);
     qemu_co_mutex_unlock(&s->lock);
     return ret;
 }

 static void dmg_close(BlockDriverState *bs)
 {
     BDRVDMGState *s = bs->opaque;

     g_free(s->types);
     g_free(s->offsets);
     g_free(s->lengths);
     g_free(s->sectors);
     g_free(s->sectorcounts);
     g_free(s->compressed_chunk);
     g_free(s->uncompressed_chunk);

     inflateEnd(&s->zstream);
 }

 static BlockDriver bdrv_dmg = {
     .format_name	= "dmg",
     .instance_size	= sizeof(BDRVDMGState),
     .bdrv_probe		= dmg_probe,
     .bdrv_open		= dmg_open,
     .bdrv_read          = dmg_co_read,
     .bdrv_close		= dmg_close,
 };

 static void bdrv_dmg_init(void)
 {
     bdrv_register(&bdrv_dmg);
 }

 block_init(bdrv_dmg_init);
	/*
	* QEMU Block driver for DMG images
	*
	* Copyright (c) 2004 Johannes E. Schindelin
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/
	#include "qemu-common.h"
	#include "block/block_int.h"
	#include "qemu/bswap.h"
	#include "qemu/module.h"
	#include <zlib.h>

	typedef struct BDRVDMGState {
	CoMutex lock;
	/* each chunk contains a certain number of sectors,
	* offsets[i] is the offset in the .dmg file,
	* lengths[i] is the length of the compressed chunk,
	* sectors[i] is the sector beginning at offsets[i],
	* sectorcounts[i] is the number of sectors in that chunk,
	* the sectors array is ordered
	* 0<=i<n_chunks */

	uint32_t n_chunks;
	uint32_t* types;
	uint64_t* offsets;
	uint64_t* lengths;
	uint64_t* sectors;
	uint64_t* sectorcounts;
	uint32_t current_chunk;
	uint8_t *compressed_chunk;
	uint8_t *uncompressed_chunk;
	z_stream zstream;
	} BDRVDMGState;

	static int dmg_probe(const uint8_t buf, int buf_size, const char filename)
	{
	int len;

	if (!filename) {
	return 0;
	}

	len = strlen(filename);
	if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
	return 2;
	}
	return 0;
	}

	static int read_uint64(BlockDriverState bs, int64_t offset, uint64_t result)
	{
	uint64_t buffer;
	int ret;

	ret = bdrv_pread(bs->file, offset, &buffer, 8);
	if (ret < 0) {
	return ret;
	}

	*result = be64_to_cpu(buffer);
	return 0;
	}

	static int read_uint32(BlockDriverState bs, int64_t offset, uint32_t result)
	{
	uint32_t buffer;
	int ret;

	ret = bdrv_pread(bs->file, offset, &buffer, 4);
	if (ret < 0) {
	return ret;
	}

	*result = be32_to_cpu(buffer);
	return 0;
	}

	static int dmg_open(BlockDriverState bs, QDict options, int flags,
	Error **errp)
	{
	BDRVDMGState *s = bs->opaque;
	uint64_t info_begin,info_end,last_in_offset,last_out_offset;
	uint32_t count, tmp;
	uint32_t max_compressed_size=1,max_sectors_per_chunk=1,i;
	int64_t offset;
	int ret;

	bs->read_only = 1;
	s->n_chunks = 0;
	s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;

	/* read offset of info blocks */
	offset = bdrv_getlength(bs->file);
	if (offset < 0) {
	ret = offset;
	goto fail;
	}
	offset -= 0x1d8;

	ret = read_uint64(bs, offset, &info_begin);
	if (ret < 0) {
	goto fail;
	} else if (info_begin == 0) {
	ret = -EINVAL;
	goto fail;
	}

	ret = read_uint32(bs, info_begin, &tmp);
	if (ret < 0) {
	goto fail;
	} else if (tmp != 0x100) {
	ret = -EINVAL;
	goto fail;
	}

	ret = read_uint32(bs, info_begin + 4, &count);
	if (ret < 0) {
	goto fail;
	} else if (count == 0) {
	ret = -EINVAL;
	goto fail;
	}
	info_end = info_begin + count;

	offset = info_begin + 0x100;

	/* read offsets */
	last_in_offset = last_out_offset = 0;
	while (offset < info_end) {
	uint32_t type;

	ret = read_uint32(bs, offset, &count);
	if (ret < 0) {
	goto fail;
	} else if (count == 0) {
	ret = -EINVAL;
	goto fail;
	}
	offset += 4;

	ret = read_uint32(bs, offset, &type);
	if (ret < 0) {
	goto fail;
	}

	if (type == 0x6d697368 && count >= 244) {
	int new_size, chunk_count;

	offset += 4;
	offset += 200;

	chunk_count = (count-204)/40;
	new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
	s->types = g_realloc(s->types, new_size/2);
	s->offsets = g_realloc(s->offsets, new_size);
	s->lengths = g_realloc(s->lengths, new_size);
	s->sectors = g_realloc(s->sectors, new_size);
	s->sectorcounts = g_realloc(s->sectorcounts, new_size);

	for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
	ret = read_uint32(bs, offset, &s->types[i]);
	if (ret < 0) {
	goto fail;
	}
	offset += 4;
	if(s->types[i]!=0x80000005 && s->types[i]!=1 && s->types[i]!=2) {
	if(s->types[i]==0xffffffff) {
	last_in_offset = s->offsets[i-1]+s->lengths[i-1];
	last_out_offset = s->sectors[i-1]+s->sectorcounts[i-1];
	}
	chunk_count--;
	i--;
	offset += 36;
	continue;
	}
	offset += 4;

	ret = read_uint64(bs, offset, &s->sectors[i]);
	if (ret < 0) {
	goto fail;
	}
	s->sectors[i] += last_out_offset;
	offset += 8;

	ret = read_uint64(bs, offset, &s->sectorcounts[i]);
	if (ret < 0) {
	goto fail;
	}
	offset += 8;

	ret = read_uint64(bs, offset, &s->offsets[i]);
	if (ret < 0) {
	goto fail;
	}
	s->offsets[i] += last_in_offset;
	offset += 8;

	ret = read_uint64(bs, offset, &s->lengths[i]);
	if (ret < 0) {
	goto fail;
	}
	offset += 8;

	if(s->lengths[i]>max_compressed_size)
	max_compressed_size = s->lengths[i];
	if(s->sectorcounts[i]>max_sectors_per_chunk)
	max_sectors_per_chunk = s->sectorcounts[i];
	}
	s->n_chunks+=chunk_count;
	}
	}

	/* initialize zlib engine */
	s->compressed_chunk = g_malloc(max_compressed_size+1);
	s->uncompressed_chunk = g_malloc(512*max_sectors_per_chunk);
	if(inflateInit(&s->zstream) != Z_OK) {
	ret = -EINVAL;
	goto fail;
	}

	s->current_chunk = s->n_chunks;

	qemu_co_mutex_init(&s->lock);
	return 0;

	fail:
	g_free(s->types);
	g_free(s->offsets);
	g_free(s->lengths);
	g_free(s->sectors);
	g_free(s->sectorcounts);
	g_free(s->compressed_chunk);
	g_free(s->uncompressed_chunk);
	return ret;
	}

	static inline int is_sector_in_chunk(BDRVDMGState* s,
	uint32_t chunk_num,int sector_num)
	{
	if(chunk_num>=s->n_chunks \|\| s->sectors[chunk_num]>sector_num \|\|
	s->sectors[chunk_num]+s->sectorcounts[chunk_num]<=sector_num)
	return 0;
	else
	return -1;
	}

	static inline uint32_t search_chunk(BDRVDMGState* s,int sector_num)
	{
	/* binary search */
	uint32_t chunk1=0,chunk2=s->n_chunks,chunk3;
	while(chunk1!=chunk2) {
	chunk3 = (chunk1+chunk2)/2;
	if(s->sectors[chunk3]>sector_num)
	chunk2 = chunk3;
	else if(s->sectors[chunk3]+s->sectorcounts[chunk3]>sector_num)
	return chunk3;
	else
	chunk1 = chunk3;
	}
	return s->n_chunks; /* error */
	}

	static inline int dmg_read_chunk(BlockDriverState *bs, int sector_num)
	{
	BDRVDMGState *s = bs->opaque;

	if(!is_sector_in_chunk(s,s->current_chunk,sector_num)) {
	int ret;
	uint32_t chunk = search_chunk(s,sector_num);

	if(chunk>=s->n_chunks)
	return -1;

	s->current_chunk = s->n_chunks;
	switch(s->types[chunk]) {
	case 0x80000005: { /* zlib compressed */
	int i;

	/* we need to buffer, because only the chunk as whole can be
	* inflated. */
	i=0;
	do {
	ret = bdrv_pread(bs->file, s->offsets[chunk] + i,
	s->compressed_chunk+i, s->lengths[chunk]-i);
	if(ret<0 && errno==EINTR)
	ret=0;
	i+=ret;
	} while(ret>=0 && ret+i<s->lengths[chunk]);

	if (ret != s->lengths[chunk])
	return -1;

	s->zstream.next_in = s->compressed_chunk;
	s->zstream.avail_in = s->lengths[chunk];
	s->zstream.next_out = s->uncompressed_chunk;
	s->zstream.avail_out = 512*s->sectorcounts[chunk];
	ret = inflateReset(&s->zstream);
	if(ret != Z_OK)
	return -1;
	ret = inflate(&s->zstream, Z_FINISH);
	if(ret != Z_STREAM_END \|\| s->zstream.total_out != 512*s->sectorcounts[chunk])
	return -1;
	break; }
	case 1: /* copy */
	ret = bdrv_pread(bs->file, s->offsets[chunk],
	s->uncompressed_chunk, s->lengths[chunk]);
	if (ret != s->lengths[chunk])
	return -1;
	break;
	case 2: /* zero */
	memset(s->uncompressed_chunk, 0, 512*s->sectorcounts[chunk]);
	break;
	}
	s->current_chunk = chunk;
	}
	return 0;
	}

	static int dmg_read(BlockDriverState *bs, int64_t sector_num,
	uint8_t *buf, int nb_sectors)
	{
	BDRVDMGState *s = bs->opaque;
	int i;

	for(i=0;i<nb_sectors;i++) {
	uint32_t sector_offset_in_chunk;
	if(dmg_read_chunk(bs, sector_num+i) != 0)
	return -1;
	sector_offset_in_chunk = sector_num+i-s->sectors[s->current_chunk];
	memcpy(buf+i512,s->uncompressed_chunk+sector_offset_in_chunk512,512);
	}
	return 0;
	}

	static coroutine_fn int dmg_co_read(BlockDriverState *bs, int64_t sector_num,
	uint8_t *buf, int nb_sectors)
	{
	int ret;
	BDRVDMGState *s = bs->opaque;
	qemu_co_mutex_lock(&s->lock);
	ret = dmg_read(bs, sector_num, buf, nb_sectors);
	qemu_co_mutex_unlock(&s->lock);
	return ret;
	}

	static void dmg_close(BlockDriverState *bs)
	{
	BDRVDMGState *s = bs->opaque;

	g_free(s->types);
	g_free(s->offsets);
	g_free(s->lengths);
	g_free(s->sectors);
	g_free(s->sectorcounts);
	g_free(s->compressed_chunk);
	g_free(s->uncompressed_chunk);

	inflateEnd(&s->zstream);
	}

	static BlockDriver bdrv_dmg = {
	.format_name = "dmg",
	.instance_size = sizeof(BDRVDMGState),
	.bdrv_probe = dmg_probe,
	.bdrv_open = dmg_open,
	.bdrv_read = dmg_co_read,
	.bdrv_close = dmg_close,
	};

	static void bdrv_dmg_init(void)
	{
	bdrv_register(&bdrv_dmg);
	}

	block_init(bdrv_dmg_init);