[mirror_qemu.git] / block-vpc.c

/*
 * Block driver for Conectix/Microsoft Virtual PC images
 *
 * Copyright (c) 2005 Alex Beregszaszi
 * Copyright (c) 2009 Kevin Wolf <kwolf@suse.de>
 *
 * 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_int.h"

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

#define HEADER_SIZE 512

//#define CACHE

enum vhd_type {
    VHD_FIXED           = 2,
    VHD_DYNAMIC         = 3,
    VHD_DIFFERENCING    = 4,
};

// always big-endian
struct vhd_footer {
    char        creator[8]; // "conectix"
    uint32_t    features;
    uint32_t    version;

    // Offset of next header structure, 0xFFFFFFFF if none
    uint64_t    data_offset;

    // Seconds since Jan 1, 2000 0:00:00 (UTC)
    uint32_t    timestamp;

    char        creator_app[4]; // "vpc "
    uint16_t    major;
    uint16_t    minor;
    char        creator_os[4]; // "Wi2k"

    uint64_t    orig_size;
    uint64_t    size;

    uint16_t    cyls;
    uint8_t     heads;
    uint8_t     secs_per_cyl;

    uint32_t    type;

    // Checksum of the Hard Disk Footer ("one's complement of the sum of all
    // the bytes in the footer without the checksum field")
    uint32_t    checksum;

    // UUID used to identify a parent hard disk (backing file)
    uint8_t     uuid[16];

    uint8_t     in_saved_state;
};

struct vhd_dyndisk_header {
    char        magic[8]; // "cxsparse"

    // Offset of next header structure, 0xFFFFFFFF if none
    uint64_t    data_offset;

    // Offset of the Block Allocation Table (BAT)
    uint64_t    table_offset;

    uint32_t    version;
    uint32_t    max_table_entries; // 32bit/entry

    // 2 MB by default, must be a power of two
    uint32_t    block_size;

    uint32_t    checksum;
    uint8_t     parent_uuid[16];
    uint32_t    parent_timestamp;
    uint32_t    reserved;

    // Backing file name (in UTF-16)
    uint8_t     parent_name[512];

    struct {
        uint32_t    platform;
        uint32_t    data_space;
        uint32_t    data_length;
        uint32_t    reserved;
        uint64_t    data_offset;
    } parent_locator[8];
};

typedef struct BDRVVPCState {
    BlockDriverState *hd;

    uint8_t footer_buf[HEADER_SIZE];
    uint64_t free_data_block_offset;
    int max_table_entries;
    uint32_t *pagetable;
    uint64_t bat_offset;
    uint64_t last_bitmap_offset;

    uint32_t block_size;
    uint32_t bitmap_size;

#ifdef CACHE
    uint8_t *pageentry_u8;
    uint32_t *pageentry_u32;
    uint16_t *pageentry_u16;

    uint64_t last_bitmap;
#endif
} BDRVVPCState;

static int vpc_probe(const uint8_t *buf, int buf_size, const char *filename)
{
    if (buf_size >= 8 && !strncmp((char *)buf, "conectix", 8))
	return 100;
    return 0;
}

static int vpc_open(BlockDriverState *bs, const char *filename, int flags)
{
    BDRVVPCState *s = bs->opaque;
    int ret, i;
    struct vhd_footer* footer;
    struct vhd_dyndisk_header* dyndisk_header;
    uint8_t buf[HEADER_SIZE];

    ret = bdrv_file_open(&s->hd, filename, flags);
    if (ret < 0)
        return ret;

    if (bdrv_pread(s->hd, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
        goto fail;

    footer = (struct vhd_footer*) s->footer_buf;
    if (strncmp(footer->creator, "conectix", 8))
        goto fail;

    // The visible size of a image in Virtual PC depends on the geometry
    // rather than on the size stored in the footer (the size in the footer
    // is too large usually)
    bs->total_sectors = (int64_t)
        be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;

    if (bdrv_pread(s->hd, be64_to_cpu(footer->data_offset), buf, HEADER_SIZE)
            != HEADER_SIZE)
        goto fail;

    dyndisk_header = (struct vhd_dyndisk_header*) buf;

    if (strncmp(dyndisk_header->magic, "cxsparse", 8))
        goto fail;


    s->block_size = be32_to_cpu(dyndisk_header->block_size);
    s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511;

    s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);
    s->pagetable = qemu_malloc(s->max_table_entries * 4);
    if (!s->pagetable)
        goto fail;

    s->bat_offset = be64_to_cpu(dyndisk_header->table_offset);
    if (bdrv_pread(s->hd, s->bat_offset, s->pagetable,
            s->max_table_entries * 4) != s->max_table_entries * 4)
	    goto fail;

    s->free_data_block_offset =
        (s->bat_offset + (s->max_table_entries * 4) + 511) & ~511;

    for (i = 0; i < s->max_table_entries; i++) {
        be32_to_cpus(&s->pagetable[i]);
        if (s->pagetable[i] != 0xFFFFFFFF) {
            int64_t next = (512 * (int64_t) s->pagetable[i]) +
                s->bitmap_size + s->block_size;

            if (next> s->free_data_block_offset)
                s->free_data_block_offset = next;
        }
    }

    s->last_bitmap_offset = (int64_t) -1;

#ifdef CACHE
    s->pageentry_u8 = qemu_malloc(512);
    if (!s->pageentry_u8)
	goto fail;
    s->pageentry_u32 = s->pageentry_u8;
    s->pageentry_u16 = s->pageentry_u8;
    s->last_pagetable = -1;
#endif

    return 0;
 fail:
    bdrv_delete(s->hd);
    return -1;
}

/*
 * Returns the absolute byte offset of the given sector in the image file.
 * If the sector is not allocated, -1 is returned instead.
 *
 * The parameter write must be 1 if the offset will be used for a write
 * operation (the block bitmaps is updated then), 0 otherwise.
 */
static inline int64_t get_sector_offset(BlockDriverState *bs,
    int64_t sector_num, int write)
{
    BDRVVPCState *s = bs->opaque;
    uint64_t offset = sector_num * 512;
    uint64_t bitmap_offset, block_offset;
    uint32_t pagetable_index, pageentry_index;

    pagetable_index = offset / s->block_size;
    pageentry_index = (offset % s->block_size) / 512;

    if (pagetable_index >= s->max_table_entries || s->pagetable[pagetable_index] == 0xffffffff)
        return -1; // not allocated

    bitmap_offset = 512 * s->pagetable[pagetable_index];
    block_offset = bitmap_offset + s->bitmap_size + (512 * pageentry_index);

    // We must ensure that we don't write to any sectors which are marked as
    // unused in the bitmap. We get away with setting all bits in the block
    // bitmap each time we write to a new block. This might cause Virtual PC to
    // miss sparse read optimization, but it's not a problem in terms of
    // correctness.
    if (write && (s->last_bitmap_offset != bitmap_offset)) {
        uint8_t bitmap[s->bitmap_size];

        s->last_bitmap_offset = bitmap_offset;
        memset(bitmap, 0xff, s->bitmap_size);
        bdrv_pwrite(s->hd, bitmap_offset, bitmap, s->bitmap_size);
    }

//    printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\n",
//	sector_num, pagetable_index, pageentry_index,
//	bitmap_offset, block_offset);

// disabled by reason
#if 0
#ifdef CACHE
    if (bitmap_offset != s->last_bitmap)
    {
	lseek(s->fd, bitmap_offset, SEEK_SET);

	s->last_bitmap = bitmap_offset;

	// Scary! Bitmap is stored as big endian 32bit entries,
	// while we used to look it up byte by byte
	read(s->fd, s->pageentry_u8, 512);
	for (i = 0; i < 128; i++)
	    be32_to_cpus(&s->pageentry_u32[i]);
    }

    if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
	return -1;
#else
    lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);

    read(s->fd, &bitmap_entry, 1);

    if ((bitmap_entry >> (pageentry_index % 8)) & 1)
	return -1; // not allocated
#endif
#endif

    return block_offset;
}

/*
 * Writes the footer to the end of the image file. This is needed when the
 * file grows as it overwrites the old footer
 *
 * Returns 0 on success and < 0 on error
 */
static int rewrite_footer(BlockDriverState* bs)
{
    int ret;
    BDRVVPCState *s = bs->opaque;
    int64_t offset = s->free_data_block_offset;

    ret = bdrv_pwrite(s->hd, offset, s->footer_buf, HEADER_SIZE);
    if (ret < 0)
        return ret;

    return 0;
}

/*
 * Allocates a new block. This involves writing a new footer and updating
 * the Block Allocation Table to use the space at the old end of the image
 * file (overwriting the old footer)
 *
 * Returns the sectors' offset in the image file on success and < 0 on error
 */
static int64_t alloc_block(BlockDriverState* bs, int64_t sector_num)
{
    BDRVVPCState *s = bs->opaque;
    int64_t bat_offset;
    uint32_t index, bat_value;
    int ret;
    uint8_t bitmap[s->bitmap_size];

    // Check if sector_num is valid
    if ((sector_num < 0) || (sector_num > bs->total_sectors))
        return -1;

    // Write entry into in-memory BAT
    index = (sector_num * 512) / s->block_size;
    if (s->pagetable[index] != 0xFFFFFFFF)
        return -1;

    s->pagetable[index] = s->free_data_block_offset / 512;

    // Initialize the block's bitmap
    memset(bitmap, 0xff, s->bitmap_size);
    bdrv_pwrite(s->hd, s->free_data_block_offset, bitmap, s->bitmap_size);

    // Write new footer (the old one will be overwritten)
    s->free_data_block_offset += s->block_size + s->bitmap_size;
    ret = rewrite_footer(bs);
    if (ret < 0)
        goto fail;

    // Write BAT entry to disk
    bat_offset = s->bat_offset + (4 * index);
    bat_value = be32_to_cpu(s->pagetable[index]);
    ret = bdrv_pwrite(s->hd, bat_offset, &bat_value, 4);
    if (ret < 0)
        goto fail;

    return get_sector_offset(bs, sector_num, 0);

fail:
    s->free_data_block_offset -= (s->block_size + s->bitmap_size);
    return -1;
}

static int vpc_read(BlockDriverState *bs, int64_t sector_num,
                    uint8_t *buf, int nb_sectors)
{
    BDRVVPCState *s = bs->opaque;
    int ret;
    int64_t offset;

    while (nb_sectors > 0) {
        offset = get_sector_offset(bs, sector_num, 0);

        if (offset == -1) {
            memset(buf, 0, 512);
        } else {
            ret = bdrv_pread(s->hd, offset, buf, 512);
            if (ret != 512)
                return -1;
        }

        nb_sectors--;
        sector_num++;
        buf += 512;
    }
    return 0;
}

static int vpc_write(BlockDriverState *bs, int64_t sector_num,
    const uint8_t *buf, int nb_sectors)
{
    BDRVVPCState *s = bs->opaque;
    int64_t offset;
    int ret;

    while (nb_sectors > 0) {
        offset = get_sector_offset(bs, sector_num, 1);

        if (offset == -1) {
            offset = alloc_block(bs, sector_num);
            if (offset < 0)
                return -1;
        }

        ret = bdrv_pwrite(s->hd, offset, buf, 512);
        if (ret != 512)
            return -1;

        nb_sectors--;
        sector_num++;
        buf += 512;
    }

    return 0;
}

static void vpc_close(BlockDriverState *bs)
{
    BDRVVPCState *s = bs->opaque;
    qemu_free(s->pagetable);
#ifdef CACHE
    qemu_free(s->pageentry_u8);
#endif
    bdrv_delete(s->hd);
}

BlockDriver bdrv_vpc = {
    "vpc",
    sizeof(BDRVVPCState),
    vpc_probe,
    vpc_open,
    vpc_read,
    vpc_write,
    vpc_close,
};
Commit	Line	Data
6a0f9e82 FB	1	/*
6a0f9e82 FB	2	* Block driver for Conectix/Microsoft Virtual PC images
5fafdf24	3	*
6a0f9e82	4	* Copyright (c) 2005 Alex Beregszaszi
15d35bc5	5	* Copyright (c) 2009 Kevin Wolf <kwolf@suse.de>
5fafdf24	6	*
6a0f9e82 FB	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	*/
faf07963	25	#include "qemu-common.h"
6a0f9e82 FB	26	#include "block_int.h"
	27
	28	/**************************************************************/
	29
	30	#define HEADER_SIZE 512
	31
	32	//#define CACHE
	33
2cfacb62 AL	34	enum vhd_type {
	35	VHD_FIXED = 2,
	36	VHD_DYNAMIC = 3,
	37	VHD_DIFFERENCING = 4,
	38	};
	39
6a0f9e82	40	// always big-endian
b9fa33a6	41	struct vhd_footer {
2cfacb62 AL	42	char creator[8]; // "conectix"
	43	uint32_t features;
	44	uint32_t version;
	45
	46	// Offset of next header structure, 0xFFFFFFFF if none
	47	uint64_t data_offset;
	48
	49	// Seconds since Jan 1, 2000 0:00:00 (UTC)
	50	uint32_t timestamp;
	51
	52	char creator_app[4]; // "vpc "
	53	uint16_t major;
	54	uint16_t minor;
	55	char creator_os[4]; // "Wi2k"
	56
	57	uint64_t orig_size;
	58	uint64_t size;
	59
	60	uint16_t cyls;
	61	uint8_t heads;
	62	uint8_t secs_per_cyl;
	63
	64	uint32_t type;
	65
	66	// Checksum of the Hard Disk Footer ("one's complement of the sum of all
	67	// the bytes in the footer without the checksum field")
	68	uint32_t checksum;
	69
	70	// UUID used to identify a parent hard disk (backing file)
	71	uint8_t uuid[16];
	72
	73	uint8_t in_saved_state;
b9fa33a6 AL	74	};
	75
	76	struct vhd_dyndisk_header {
2cfacb62 AL	77	char magic[8]; // "cxsparse"
	78
	79	// Offset of next header structure, 0xFFFFFFFF if none
	80	uint64_t data_offset;
	81
	82	// Offset of the Block Allocation Table (BAT)
	83	uint64_t table_offset;
	84
	85	uint32_t version;
	86	uint32_t max_table_entries; // 32bit/entry
	87
	88	// 2 MB by default, must be a power of two
	89	uint32_t block_size;
	90
	91	uint32_t checksum;
	92	uint8_t parent_uuid[16];
	93	uint32_t parent_timestamp;
	94	uint32_t reserved;
	95
	96	// Backing file name (in UTF-16)
	97	uint8_t parent_name[512];
	98
	99	struct {
	100	uint32_t platform;
	101	uint32_t data_space;
	102	uint32_t data_length;
	103	uint32_t reserved;
	104	uint64_t data_offset;
	105	} parent_locator[8];
6a0f9e82 FB	106	};
	107
	108	typedef struct BDRVVPCState {
b71d1c2e	109	BlockDriverState *hd;
3b46e624	110
15d35bc5 AL	111	uint8_t footer_buf[HEADER_SIZE];
15d35bc5 AL	112	uint64_t free_data_block_offset;
2cfacb62	113	int max_table_entries;
6a0f9e82	114	uint32_t *pagetable;
15d35bc5 AL	115	uint64_t bat_offset;
15d35bc5 AL	116	uint64_t last_bitmap_offset;
6a0f9e82	117
2cfacb62	118	uint32_t block_size;
15d35bc5 AL	119	uint32_t bitmap_size;
15d35bc5 AL	120
6a0f9e82 FB	121	#ifdef CACHE
	122	uint8_t *pageentry_u8;
	123	uint32_t *pageentry_u32;
	124	uint16_t *pageentry_u16;
3b46e624	125
6a0f9e82 FB	126	uint64_t last_bitmap;
	127	#endif
	128	} BDRVVPCState;
	129
	130	static int vpc_probe(const uint8_t buf, int buf_size, const char filename)
	131	{
ffe8ab83	132	if (buf_size >= 8 && !strncmp((char *)buf, "conectix", 8))
6a0f9e82	133	return 100;
6a0f9e82 FB	134	return 0;
	135	}
	136
83f64091	137	static int vpc_open(BlockDriverState bs, const char filename, int flags)
6a0f9e82 FB	138	{
6a0f9e82 FB	139	BDRVVPCState *s = bs->opaque;
b71d1c2e	140	int ret, i;
b9fa33a6 AL	141	struct vhd_footer* footer;
	142	struct vhd_dyndisk_header* dyndisk_header;
	143	uint8_t buf[HEADER_SIZE];
6a0f9e82	144
b71d1c2e AL	145	ret = bdrv_file_open(&s->hd, filename, flags);
	146	if (ret < 0)
	147	return ret;
6a0f9e82	148
15d35bc5	149	if (bdrv_pread(s->hd, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
6a0f9e82 FB	150	goto fail;
6a0f9e82 FB	151
15d35bc5	152	footer = (struct vhd_footer*) s->footer_buf;
b9fa33a6	153	if (strncmp(footer->creator, "conectix", 8))
6a0f9e82	154	goto fail;
6a0f9e82	155
1fa79228 AL	156	// The visible size of a image in Virtual PC depends on the geometry
	157	// rather than on the size stored in the footer (the size in the footer
	158	// is too large usually)
	159	bs->total_sectors = (int64_t)
	160	be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
	161
b71d1c2e AL	162	if (bdrv_pread(s->hd, be64_to_cpu(footer->data_offset), buf, HEADER_SIZE)
b71d1c2e AL	163	!= HEADER_SIZE)
6a0f9e82 FB	164	goto fail;
6a0f9e82 FB	165
b9fa33a6 AL	166	dyndisk_header = (struct vhd_dyndisk_header*) buf;
	167
	168	if (strncmp(dyndisk_header->magic, "cxsparse", 8))
	169	goto fail;
6a0f9e82	170
6a0f9e82	171
15d35bc5 AL	172	s->block_size = be32_to_cpu(dyndisk_header->block_size);
	173	s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511;
	174
2cfacb62 AL	175	s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);
2cfacb62 AL	176	s->pagetable = qemu_malloc(s->max_table_entries * 4);
6a0f9e82	177	if (!s->pagetable)
b71d1c2e AL	178	goto fail;
b71d1c2e AL	179
15d35bc5 AL	180	s->bat_offset = be64_to_cpu(dyndisk_header->table_offset);
	181	if (bdrv_pread(s->hd, s->bat_offset, s->pagetable,
	182	s->max_table_entries * 4) != s->max_table_entries * 4)
b71d1c2e AL	183	goto fail;
b71d1c2e AL	184
15d35bc5 AL	185	s->free_data_block_offset =
	186	(s->bat_offset + (s->max_table_entries * 4) + 511) & ~511;
	187
	188	for (i = 0; i < s->max_table_entries; i++) {
	189	be32_to_cpus(&s->pagetable[i]);
	190	if (s->pagetable[i] != 0xFFFFFFFF) {
	191	int64_t next = (512 * (int64_t) s->pagetable[i]) +
	192	s->bitmap_size + s->block_size;
	193
	194	if (next> s->free_data_block_offset)
	195	s->free_data_block_offset = next;
	196	}
	197	}
	198
	199	s->last_bitmap_offset = (int64_t) -1;
6a0f9e82	200
6a0f9e82 FB	201	#ifdef CACHE
	202	s->pageentry_u8 = qemu_malloc(512);
	203	if (!s->pageentry_u8)
	204	goto fail;
	205	s->pageentry_u32 = s->pageentry_u8;
	206	s->pageentry_u16 = s->pageentry_u8;
	207	s->last_pagetable = -1;
	208	#endif
	209
	210	return 0;
	211	fail:
b71d1c2e	212	bdrv_delete(s->hd);
6a0f9e82 FB	213	return -1;
	214	}
	215
b71d1c2e AL	216	/*
	217	* Returns the absolute byte offset of the given sector in the image file.
	218	* If the sector is not allocated, -1 is returned instead.
15d35bc5 AL	219	*
	220	* The parameter write must be 1 if the offset will be used for a write
	221	* operation (the block bitmaps is updated then), 0 otherwise.
b71d1c2e	222	*/
15d35bc5 AL	223	static inline int64_t get_sector_offset(BlockDriverState *bs,
15d35bc5 AL	224	int64_t sector_num, int write)
6a0f9e82 FB	225	{
	226	BDRVVPCState *s = bs->opaque;
	227	uint64_t offset = sector_num * 512;
	228	uint64_t bitmap_offset, block_offset;
	229	uint32_t pagetable_index, pageentry_index;
	230
2cfacb62 AL	231	pagetable_index = offset / s->block_size;
2cfacb62 AL	232	pageentry_index = (offset % s->block_size) / 512;
3b46e624	233
15d35bc5 AL	234	if (pagetable_index >= s->max_table_entries \|\| s->pagetable[pagetable_index] == 0xffffffff)
15d35bc5 AL	235	return -1; // not allocated
6a0f9e82 FB	236
6a0f9e82 FB	237	bitmap_offset = 512 * s->pagetable[pagetable_index];
15d35bc5 AL	238	block_offset = bitmap_offset + s->bitmap_size + (512 * pageentry_index);
	239
	240	// We must ensure that we don't write to any sectors which are marked as
	241	// unused in the bitmap. We get away with setting all bits in the block
	242	// bitmap each time we write to a new block. This might cause Virtual PC to
	243	// miss sparse read optimization, but it's not a problem in terms of
	244	// correctness.
	245	if (write && (s->last_bitmap_offset != bitmap_offset)) {
	246	uint8_t bitmap[s->bitmap_size];
	247
	248	s->last_bitmap_offset = bitmap_offset;
	249	memset(bitmap, 0xff, s->bitmap_size);
	250	bdrv_pwrite(s->hd, bitmap_offset, bitmap, s->bitmap_size);
	251	}
3b46e624	252
26a76461	253	// printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\n",
6a0f9e82 FB	254	// sector_num, pagetable_index, pageentry_index,
	255	// bitmap_offset, block_offset);
	256
	257	// disabled by reason
	258	#if 0
	259	#ifdef CACHE
	260	if (bitmap_offset != s->last_bitmap)
	261	{
	262	lseek(s->fd, bitmap_offset, SEEK_SET);
	263
	264	s->last_bitmap = bitmap_offset;
5fafdf24	265
6a0f9e82 FB	266	// Scary! Bitmap is stored as big endian 32bit entries,
	267	// while we used to look it up byte by byte
	268	read(s->fd, s->pageentry_u8, 512);
	269	for (i = 0; i < 128; i++)
	270	be32_to_cpus(&s->pageentry_u32[i]);
	271	}
	272
	273	if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
	274	return -1;
	275	#else
	276	lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);
5fafdf24	277
6a0f9e82 FB	278	read(s->fd, &bitmap_entry, 1);
	279
	280	if ((bitmap_entry >> (pageentry_index % 8)) & 1)
	281	return -1; // not allocated
	282	#endif
	283	#endif
6a0f9e82	284
b71d1c2e	285	return block_offset;
6a0f9e82 FB	286	}
6a0f9e82 FB	287
15d35bc5 AL	288	/*
	289	* Writes the footer to the end of the image file. This is needed when the
	290	* file grows as it overwrites the old footer
	291	*
	292	* Returns 0 on success and < 0 on error
	293	*/
	294	static int rewrite_footer(BlockDriverState* bs)
	295	{
	296	int ret;
	297	BDRVVPCState *s = bs->opaque;
	298	int64_t offset = s->free_data_block_offset;
	299
	300	ret = bdrv_pwrite(s->hd, offset, s->footer_buf, HEADER_SIZE);
	301	if (ret < 0)
	302	return ret;
	303
	304	return 0;
	305	}
	306
	307	/*
	308	* Allocates a new block. This involves writing a new footer and updating
	309	* the Block Allocation Table to use the space at the old end of the image
	310	* file (overwriting the old footer)
	311	*
	312	* Returns the sectors' offset in the image file on success and < 0 on error
	313	*/
	314	static int64_t alloc_block(BlockDriverState* bs, int64_t sector_num)
	315	{
	316	BDRVVPCState *s = bs->opaque;
	317	int64_t bat_offset;
	318	uint32_t index, bat_value;
	319	int ret;
	320	uint8_t bitmap[s->bitmap_size];
	321
	322	// Check if sector_num is valid
	323	if ((sector_num < 0) \|\| (sector_num > bs->total_sectors))
	324	return -1;
	325
	326	// Write entry into in-memory BAT
	327	index = (sector_num * 512) / s->block_size;
	328	if (s->pagetable[index] != 0xFFFFFFFF)
	329	return -1;
	330
	331	s->pagetable[index] = s->free_data_block_offset / 512;
	332
	333	// Initialize the block's bitmap
	334	memset(bitmap, 0xff, s->bitmap_size);
	335	bdrv_pwrite(s->hd, s->free_data_block_offset, bitmap, s->bitmap_size);
	336
	337	// Write new footer (the old one will be overwritten)
	338	s->free_data_block_offset += s->block_size + s->bitmap_size;
	339	ret = rewrite_footer(bs);
	340	if (ret < 0)
	341	goto fail;
	342
	343	// Write BAT entry to disk
	344	bat_offset = s->bat_offset + (4 * index);
	345	bat_value = be32_to_cpu(s->pagetable[index]);
	346	ret = bdrv_pwrite(s->hd, bat_offset, &bat_value, 4);
	347	if (ret < 0)
	348	goto fail;
	349
	350	return get_sector_offset(bs, sector_num, 0);
	351
352	fail:
353	s->free_data_block_offset -= (s->block_size + s->bitmap_size);
354	return -1;
355	}
356
5fafdf24	357	static int vpc_read(BlockDriverState *bs, int64_t sector_num,
6a0f9e82 FB	358	uint8_t *buf, int nb_sectors)
	359	{
	360	BDRVVPCState *s = bs->opaque;
	361	int ret;
b71d1c2e	362	int64_t offset;
6a0f9e82 FB	363
6a0f9e82 FB	364	while (nb_sectors > 0) {
15d35bc5	365	offset = get_sector_offset(bs, sector_num, 0);
b71d1c2e AL	366
b71d1c2e AL	367	if (offset == -1) {
6a0f9e82	368	memset(buf, 0, 512);
b71d1c2e AL	369	} else {
	370	ret = bdrv_pread(s->hd, offset, buf, 512);
	371	if (ret != 512)
	372	return -1;
	373	}
	374
6a0f9e82 FB	375	nb_sectors--;
	376	sector_num++;
	377	buf += 512;
	378	}
	379	return 0;
	380	}
	381
15d35bc5 AL	382	static int vpc_write(BlockDriverState *bs, int64_t sector_num,
	383	const uint8_t *buf, int nb_sectors)
	384	{
	385	BDRVVPCState *s = bs->opaque;
	386	int64_t offset;
	387	int ret;
	388
	389	while (nb_sectors > 0) {
	390	offset = get_sector_offset(bs, sector_num, 1);
	391
	392	if (offset == -1) {
	393	offset = alloc_block(bs, sector_num);
	394	if (offset < 0)
	395	return -1;
	396	}
	397
	398	ret = bdrv_pwrite(s->hd, offset, buf, 512);
	399	if (ret != 512)
	400	return -1;
	401
	402	nb_sectors--;
	403	sector_num++;
	404	buf += 512;
	405	}
	406
	407	return 0;
	408	}
	409
6a0f9e82 FB	410	static void vpc_close(BlockDriverState *bs)
	411	{
	412	BDRVVPCState *s = bs->opaque;
	413	qemu_free(s->pagetable);
	414	#ifdef CACHE
	415	qemu_free(s->pageentry_u8);
	416	#endif
b71d1c2e	417	bdrv_delete(s->hd);
6a0f9e82 FB	418	}
	419
	420	BlockDriver bdrv_vpc = {
	421	"vpc",
	422	sizeof(BDRVVPCState),
	423	vpc_probe,
	424	vpc_open,
	425	vpc_read,
15d35bc5	426	vpc_write,
6a0f9e82 FB	427	vpc_close,
6a0f9e82 FB	428	};