block/bochs.c - qemu - Git at Google

 /*
  * Block driver for the various disk image formats used by Bochs
  * Currently only for "growing" type in read-only mode
  *
  * Copyright (c) 2005 Alex Beregszaszi
  *
  * 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/module.h"

 /**************************************************************/

 #define HEADER_MAGIC "Bochs Virtual HD Image"
 #define HEADER_VERSION 0x00020000
 #define HEADER_V1 0x00010000
 #define HEADER_SIZE 512

 #define REDOLOG_TYPE "Redolog"
 #define GROWING_TYPE "Growing"

 // not allocated: 0xffffffff

 // always little-endian
 struct bochs_header {
     char magic[32];     /* "Bochs Virtual HD Image" */
     char type[16];      /* "Redolog" */
     char subtype[16];   /* "Undoable" / "Volatile" / "Growing" */
     uint32_t version;
     uint32_t header;    /* size of header */

     uint32_t catalog;   /* num of entries */
     uint32_t bitmap;    /* bitmap size */
     uint32_t extent;    /* extent size */

     union {
         struct {
             uint32_t reserved;  /* for ??? */
             uint64_t disk;      /* disk size */
             char padding[HEADER_SIZE - 64 - 20 - 12];
         } QEMU_PACKED redolog;
         struct {
             uint64_t disk;      /* disk size */
             char padding[HEADER_SIZE - 64 - 20 - 8];
         } QEMU_PACKED redolog_v1;
         char padding[HEADER_SIZE - 64 - 20];
     } extra;
 } QEMU_PACKED;

 typedef struct BDRVBochsState {
     CoMutex lock;
     uint32_t *catalog_bitmap;
     uint32_t catalog_size;

     uint32_t data_offset;

     uint32_t bitmap_blocks;
     uint32_t extent_blocks;
     uint32_t extent_size;
 } BDRVBochsState;

 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
 {
     const struct bochs_header *bochs = (const void *)buf;

     if (buf_size < HEADER_SIZE)
 	return 0;

     if (!strcmp(bochs->magic, HEADER_MAGIC) &&
 	!strcmp(bochs->type, REDOLOG_TYPE) &&
 	!strcmp(bochs->subtype, GROWING_TYPE) &&
 	((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
 	(le32_to_cpu(bochs->version) == HEADER_V1)))
 	return 100;

     return 0;
 }

 static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
                       Error **errp)
 {
     BDRVBochsState *s = bs->opaque;
     uint32_t i;
     struct bochs_header bochs;
     int ret;

     bs->read_only = 1; // no write support yet

     ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));
     if (ret < 0) {
         return ret;
     }

     if (strcmp(bochs.magic, HEADER_MAGIC) ||
         strcmp(bochs.type, REDOLOG_TYPE) ||
         strcmp(bochs.subtype, GROWING_TYPE) ||
 	((le32_to_cpu(bochs.version) != HEADER_VERSION) &&
 	(le32_to_cpu(bochs.version) != HEADER_V1))) {
         error_setg(errp, "Image not in Bochs format");
         return -EINVAL;
     }

     if (le32_to_cpu(bochs.version) == HEADER_V1) {
         bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512;
     } else {
         bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
     }

     /* Limit to 1M entries to avoid unbounded allocation. This is what is
      * needed for the largest image that bximage can create (~8 TB). */
     s->catalog_size = le32_to_cpu(bochs.catalog);
     if (s->catalog_size > 0x100000) {
         error_setg(errp, "Catalog size is too large");
         return -EFBIG;
     }

     s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size);
     if (s->catalog_size && s->catalog_bitmap == NULL) {
         error_setg(errp, "Could not allocate memory for catalog");
         return -ENOMEM;
     }

     ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap,
                      s->catalog_size * 4);
     if (ret < 0) {
         goto fail;
     }

     for (i = 0; i < s->catalog_size; i++)
 	le32_to_cpus(&s->catalog_bitmap[i]);

     s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);

     s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512;
     s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;

     s->extent_size = le32_to_cpu(bochs.extent);
     if (s->extent_size < BDRV_SECTOR_SIZE) {
         /* bximage actually never creates extents smaller than 4k */
         error_setg(errp, "Extent size must be at least 512");
         ret = -EINVAL;
         goto fail;
     } else if (!is_power_of_2(s->extent_size)) {
         error_setg(errp, "Extent size %" PRIu32 " is not a power of two",
                    s->extent_size);
         ret = -EINVAL;
         goto fail;
     } else if (s->extent_size > 0x800000) {
         error_setg(errp, "Extent size %" PRIu32 " is too large",
                    s->extent_size);
         ret = -EINVAL;
         goto fail;
     }

     if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors,
                                        s->extent_size / BDRV_SECTOR_SIZE))
     {
         error_setg(errp, "Catalog size is too small for this disk size");
         ret = -EINVAL;
         goto fail;
     }

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

 fail:
     g_free(s->catalog_bitmap);
     return ret;
 }

 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
 {
     BDRVBochsState *s = bs->opaque;
     uint64_t offset = sector_num * 512;
     uint64_t extent_index, extent_offset, bitmap_offset;
     char bitmap_entry;
     int ret;

     // seek to sector
     extent_index = offset / s->extent_size;
     extent_offset = (offset % s->extent_size) / 512;

     if (s->catalog_bitmap[extent_index] == 0xffffffff) {
 	return 0; /* not allocated */
     }

     bitmap_offset = s->data_offset +
         (512 * (uint64_t) s->catalog_bitmap[extent_index] *
         (s->extent_blocks + s->bitmap_blocks));

     /* read in bitmap for current extent */
     ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8),
                      &bitmap_entry, 1);
     if (ret < 0) {
         return ret;
     }

     if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
 	return 0; /* not allocated */
     }

     return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
 }

 static int bochs_read(BlockDriverState *bs, int64_t sector_num,
                     uint8_t *buf, int nb_sectors)
 {
     int ret;

     while (nb_sectors > 0) {
         int64_t block_offset = seek_to_sector(bs, sector_num);
         if (block_offset < 0) {
             return block_offset;
         } else if (block_offset > 0) {
             ret = bdrv_pread(bs->file, block_offset, buf, 512);
             if (ret < 0) {
                 return ret;
             }
         } else {
             memset(buf, 0, 512);
         }
         nb_sectors--;
         sector_num++;
         buf += 512;
     }
     return 0;
 }

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

 static void bochs_close(BlockDriverState *bs)
 {
     BDRVBochsState *s = bs->opaque;
     g_free(s->catalog_bitmap);
 }

 static BlockDriver bdrv_bochs = {
     .format_name	= "bochs",
     .instance_size	= sizeof(BDRVBochsState),
     .bdrv_probe		= bochs_probe,
     .bdrv_open		= bochs_open,
     .bdrv_read          = bochs_co_read,
     .bdrv_close		= bochs_close,
 };

 static void bdrv_bochs_init(void)
 {
     bdrv_register(&bdrv_bochs);
 }

 block_init(bdrv_bochs_init);
	/*
	* Block driver for the various disk image formats used by Bochs
	* Currently only for "growing" type in read-only mode
	*
	* Copyright (c) 2005 Alex Beregszaszi
	*
	* 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/module.h"

	/**************************************************************/

	#define HEADER_MAGIC "Bochs Virtual HD Image"
	#define HEADER_VERSION 0x00020000
	#define HEADER_V1 0x00010000
	#define HEADER_SIZE 512

	#define REDOLOG_TYPE "Redolog"
	#define GROWING_TYPE "Growing"

	// not allocated: 0xffffffff

	// always little-endian
	struct bochs_header {
	char magic[32]; /* "Bochs Virtual HD Image" */
	char type[16]; /* "Redolog" */
	char subtype[16]; /* "Undoable" / "Volatile" / "Growing" */
	uint32_t version;
	uint32_t header; /* size of header */

	uint32_t catalog; /* num of entries */
	uint32_t bitmap; /* bitmap size */
	uint32_t extent; /* extent size */

	union {
	struct {
	uint32_t reserved; /* for ??? */
	uint64_t disk; /* disk size */
	char padding[HEADER_SIZE - 64 - 20 - 12];
	} QEMU_PACKED redolog;
	struct {
	uint64_t disk; /* disk size */
	char padding[HEADER_SIZE - 64 - 20 - 8];
	} QEMU_PACKED redolog_v1;
	char padding[HEADER_SIZE - 64 - 20];
	} extra;
	} QEMU_PACKED;

	typedef struct BDRVBochsState {
	CoMutex lock;
	uint32_t *catalog_bitmap;
	uint32_t catalog_size;

	uint32_t data_offset;

	uint32_t bitmap_blocks;
	uint32_t extent_blocks;
	uint32_t extent_size;
	} BDRVBochsState;

	static int bochs_probe(const uint8_t buf, int buf_size, const char filename)
	{
	const struct bochs_header bochs = (const void )buf;

	if (buf_size < HEADER_SIZE)
	return 0;

	if (!strcmp(bochs->magic, HEADER_MAGIC) &&
	!strcmp(bochs->type, REDOLOG_TYPE) &&
	!strcmp(bochs->subtype, GROWING_TYPE) &&
	((le32_to_cpu(bochs->version) == HEADER_VERSION) \|\|
	(le32_to_cpu(bochs->version) == HEADER_V1)))
	return 100;

	return 0;
	}

	static int bochs_open(BlockDriverState bs, QDict options, int flags,
	Error **errp)
	{
	BDRVBochsState *s = bs->opaque;
	uint32_t i;
	struct bochs_header bochs;
	int ret;

	bs->read_only = 1; // no write support yet

	ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));
	if (ret < 0) {
	return ret;
	}

	if (strcmp(bochs.magic, HEADER_MAGIC) \|\|
	strcmp(bochs.type, REDOLOG_TYPE) \|\|
	strcmp(bochs.subtype, GROWING_TYPE) \|\|
	((le32_to_cpu(bochs.version) != HEADER_VERSION) &&
	(le32_to_cpu(bochs.version) != HEADER_V1))) {
	error_setg(errp, "Image not in Bochs format");
	return -EINVAL;
	}

	if (le32_to_cpu(bochs.version) == HEADER_V1) {
	bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512;
	} else {
	bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
	}

	/* Limit to 1M entries to avoid unbounded allocation. This is what is
	* needed for the largest image that bximage can create (~8 TB). */
	s->catalog_size = le32_to_cpu(bochs.catalog);
	if (s->catalog_size > 0x100000) {
	error_setg(errp, "Catalog size is too large");
	return -EFBIG;
	}

	s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size);
	if (s->catalog_size && s->catalog_bitmap == NULL) {
	error_setg(errp, "Could not allocate memory for catalog");
	return -ENOMEM;
	}

	ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap,
	s->catalog_size * 4);
	if (ret < 0) {
	goto fail;
	}

	for (i = 0; i < s->catalog_size; i++)
	le32_to_cpus(&s->catalog_bitmap[i]);

	s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);

	s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512;
	s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;

	s->extent_size = le32_to_cpu(bochs.extent);
	if (s->extent_size < BDRV_SECTOR_SIZE) {
	/* bximage actually never creates extents smaller than 4k */
	error_setg(errp, "Extent size must be at least 512");
	ret = -EINVAL;
	goto fail;
	} else if (!is_power_of_2(s->extent_size)) {
	error_setg(errp, "Extent size %" PRIu32 " is not a power of two",
	s->extent_size);
	ret = -EINVAL;
	goto fail;
	} else if (s->extent_size > 0x800000) {
	error_setg(errp, "Extent size %" PRIu32 " is too large",
	s->extent_size);
	ret = -EINVAL;
	goto fail;
	}

	if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors,
	s->extent_size / BDRV_SECTOR_SIZE))
	{
	error_setg(errp, "Catalog size is too small for this disk size");
	ret = -EINVAL;
	goto fail;
	}

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

	fail:
	g_free(s->catalog_bitmap);
	return ret;
	}

	static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
	{
	BDRVBochsState *s = bs->opaque;
	uint64_t offset = sector_num * 512;
	uint64_t extent_index, extent_offset, bitmap_offset;
	char bitmap_entry;
	int ret;

	// seek to sector
	extent_index = offset / s->extent_size;
	extent_offset = (offset % s->extent_size) / 512;

	if (s->catalog_bitmap[extent_index] == 0xffffffff) {
	return 0; /* not allocated */
	}

	bitmap_offset = s->data_offset +
	(512 * (uint64_t) s->catalog_bitmap[extent_index] *
	(s->extent_blocks + s->bitmap_blocks));

	/* read in bitmap for current extent */
	ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8),
	&bitmap_entry, 1);
	if (ret < 0) {
	return ret;
	}

	if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
	return 0; /* not allocated */
	}

	return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
	}

	static int bochs_read(BlockDriverState *bs, int64_t sector_num,
	uint8_t *buf, int nb_sectors)
	{
	int ret;

	while (nb_sectors > 0) {
	int64_t block_offset = seek_to_sector(bs, sector_num);
	if (block_offset < 0) {
	return block_offset;
	} else if (block_offset > 0) {
	ret = bdrv_pread(bs->file, block_offset, buf, 512);
	if (ret < 0) {
	return ret;
	}
	} else {
	memset(buf, 0, 512);
	}
	nb_sectors--;
	sector_num++;
	buf += 512;
	}
	return 0;
	}

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

	static void bochs_close(BlockDriverState *bs)
	{
	BDRVBochsState *s = bs->opaque;
	g_free(s->catalog_bitmap);
	}

	static BlockDriver bdrv_bochs = {
	.format_name = "bochs",
	.instance_size = sizeof(BDRVBochsState),
	.bdrv_probe = bochs_probe,
	.bdrv_open = bochs_open,
	.bdrv_read = bochs_co_read,
	.bdrv_close = bochs_close,
	};

	static void bdrv_bochs_init(void)
	{
	bdrv_register(&bdrv_bochs);
	}

	block_init(bdrv_bochs_init);