aboutsummaryrefslogtreecommitdiff
path: root/block/bochs.c
blob: 199ac2b9af7ba4b61a64b4171c2700fadf0f71cc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
/*
 * 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);