Archipelago » qemu

/*

 * QEMU System Emulator block driver

 * 

 * Copyright (c) 2003 Fabrice Bellard

 * 

 * 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 "vl.h"

#ifndef _WIN32

#include <sys/mman.h>

#endif

#include "cow.h"

struct BlockDriverState {

    int fd; /* if -1, only COW mappings */

    int64_t total_sectors;

    int read_only; /* if true, the media is read only */

    int inserted; /* if true, the media is present */

    int removable; /* if true, the media can be removed */

    int locked;    /* if true, the media cannot temporarily be ejected */

    /* event callback when inserting/removing */

    void (*change_cb)(void *opaque);

    void *change_opaque;

    uint8_t *cow_bitmap; /* if non NULL, COW mappings are used first */

    uint8_t *cow_bitmap_addr; /* mmap address of cow_bitmap */

    int cow_bitmap_size;

    int cow_fd;

    int64_t cow_sectors_offset;

    int boot_sector_enabled;

    uint8_t boot_sector_data[512];

    char filename[1024];

    /* NOTE: the following infos are only hints for real hardware

       drivers. They are not used by the block driver */

    int cyls, heads, secs;

    int type;

    char device_name[32];

    BlockDriverState *next;

};

static BlockDriverState *bdrv_first;

/* create a new block device (by default it is empty) */

BlockDriverState *bdrv_new(const char *device_name)

{

    BlockDriverState **pbs, *bs;

    bs = qemu_mallocz(sizeof(BlockDriverState));

    if(!bs)

        return NULL;

    pstrcpy(bs->device_name, sizeof(bs->device_name), device_name);

    /* insert at the end */

    pbs = &bdrv_first;

    while (*pbs != NULL)

        pbs = &(*pbs)->next;

    *pbs = bs;

    return bs;

}

int bdrv_open(BlockDriverState *bs, const char *filename, int snapshot)

{

    int fd;

    int64_t size;

    struct cow_header_v2 cow_header;

#ifndef _WIN32

    char template[] = "/tmp/vl.XXXXXX";

    int cow_fd;

    struct stat st;

#endif

    bs->read_only = 0;

    bs->fd = -1;

    bs->cow_fd = -1;

    bs->cow_bitmap = NULL;

    pstrcpy(bs->filename, sizeof(bs->filename), filename);

    /* open standard HD image */

#ifdef _WIN32

    fd = open(filename, O_RDWR | O_BINARY);

#else

    fd = open(filename, O_RDWR | O_LARGEFILE);

#endif

    if (fd < 0) {

        /* read only image on disk */

#ifdef _WIN32

        fd = open(filename, O_RDONLY | O_BINARY);

#else

        fd = open(filename, O_RDONLY | O_LARGEFILE);

#endif

        if (fd < 0) {

            perror(filename);

            goto fail;

        }

        if (!snapshot)

            bs->read_only = 1;

    }

    bs->fd = fd;

    /* see if it is a cow image */

    if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) {

        fprintf(stderr, "%s: could not read header\n", filename);

        goto fail;

    }

#ifndef _WIN32

    if (be32_to_cpu(cow_header.magic) == COW_MAGIC &&

        be32_to_cpu(cow_header.version) == COW_VERSION) {

        /* cow image found */

        size = cow_header.size;

#ifndef WORDS_BIGENDIAN

        size = bswap64(size);

#endif    

        bs->total_sectors = size / 512;

        bs->cow_fd = fd;

        bs->fd = -1;

        if (cow_header.backing_file[0] != '\0') {

            if (stat(cow_header.backing_file, &st) != 0) {

                fprintf(stderr, "%s: could not find original disk image '%s'\n", filename, cow_header.backing_file);

                goto fail;

            }

            if (st.st_mtime != be32_to_cpu(cow_header.mtime)) {

                fprintf(stderr, "%s: original raw disk image '%s' does not match saved timestamp\n", filename, cow_header.backing_file);

                goto fail;

            }

            fd = open(cow_header.backing_file, O_RDONLY | O_LARGEFILE);

            if (fd < 0)

                goto fail;

            bs->fd = fd;

        }

        /* mmap the bitmap */

        bs->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header);

        bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size), 

                                   bs->cow_bitmap_size, 

                                   PROT_READ | PROT_WRITE,

                                   MAP_SHARED, bs->cow_fd, 0);

        if (bs->cow_bitmap_addr == MAP_FAILED)

            goto fail;

        bs->cow_bitmap = bs->cow_bitmap_addr + sizeof(cow_header);

        bs->cow_sectors_offset = (bs->cow_bitmap_size + 511) & ~511;

        snapshot = 0;

    } else 

#endif

    {

        /* standard raw image */

        size = lseek64(fd, 0, SEEK_END);

        bs->total_sectors = size / 512;

        bs->fd = fd;

    }

#ifndef _WIN32

    if (snapshot) {

        /* create a temporary COW file */

        cow_fd = mkstemp64(template);

        if (cow_fd < 0)

            goto fail;

        bs->cow_fd = cow_fd;

        unlink(template);

        /* just need to allocate bitmap */

        bs->cow_bitmap_size = (bs->total_sectors + 7) >> 3;

        bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size), 

                                   bs->cow_bitmap_size, 

                                   PROT_READ | PROT_WRITE,

                                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

        if (bs->cow_bitmap_addr == MAP_FAILED)

            goto fail;

        bs->cow_bitmap = bs->cow_bitmap_addr;

        bs->cow_sectors_offset = 0;

    }

#endif

    bs->inserted = 1;

    /* call the change callback */

    if (bs->change_cb)

        bs->change_cb(bs->change_opaque);

    return 0;

 fail:

    bdrv_close(bs);

    return -1;

}

void bdrv_close(BlockDriverState *bs)

{

    if (bs->inserted) {

#ifndef _WIN32

        /* we unmap the mapping so that it is written to the COW file */

        if (bs->cow_bitmap_addr)

            munmap(bs->cow_bitmap_addr, bs->cow_bitmap_size);

#endif

        if (bs->cow_fd >= 0)

            close(bs->cow_fd);

        if (bs->fd >= 0)

            close(bs->fd);

        bs->inserted = 0;

        /* call the change callback */

        if (bs->change_cb)

            bs->change_cb(bs->change_opaque);

    }

}

void bdrv_delete(BlockDriverState *bs)

{

    bdrv_close(bs);

    qemu_free(bs);

}

static inline void set_bit(uint8_t *bitmap, int64_t bitnum)

{

    bitmap[bitnum / 8] |= (1 << (bitnum%8));

}

static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum)

{

    return !!(bitmap[bitnum / 8] & (1 << (bitnum%8)));

}

/* Return true if first block has been changed (ie. current version is

 * in COW file).  Set the number of continuous blocks for which that

 * is true. */

static int is_changed(uint8_t *bitmap,

                      int64_t sector_num, int nb_sectors,

                      int *num_same)

{

    int changed;

    if (!bitmap || nb_sectors == 0) {

        *num_same = nb_sectors;

        return 0;

    }

    changed = is_bit_set(bitmap, sector_num);

    for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) {

        if (is_bit_set(bitmap, sector_num + *num_same) != changed)

            break;

    }

    return changed;

}

/* commit COW file into the raw image */

int bdrv_commit(BlockDriverState *bs)

{

    int64_t i;

    uint8_t *cow_bitmap;

    if (!bs->inserted)

        return -1;

    if (!bs->cow_bitmap) {

        fprintf(stderr, "Already committed to %s\n", bs->filename);

        return 0;

    }

    if (bs->read_only) {

        fprintf(stderr, "Can't commit to %s: read-only\n", bs->filename);

        return -1;

    }

    cow_bitmap = bs->cow_bitmap;

    for (i = 0; i < bs->total_sectors; i++) {

        if (is_bit_set(cow_bitmap, i)) {

            unsigned char sector[512];

            if (bdrv_read(bs, i, sector, 1) != 0) {

                fprintf(stderr, "Error reading sector %lli: aborting commit\n",

                        (long long)i);

                return -1;

            }

            /* Make bdrv_write write to real file for a moment. */

            bs->cow_bitmap = NULL;

            if (bdrv_write(bs, i, sector, 1) != 0) {

                fprintf(stderr, "Error writing sector %lli: aborting commit\n",

                        (long long)i);

                bs->cow_bitmap = cow_bitmap;

                return -1;

            }

            bs->cow_bitmap = cow_bitmap;

        }

    }

    fprintf(stderr, "Committed snapshot to %s\n", bs->filename);

    return 0;

}

/* return -1 if error */

int bdrv_read(BlockDriverState *bs, int64_t sector_num, 

              uint8_t *buf, int nb_sectors)

{

    int ret, n, fd;

    int64_t offset;

    if (!bs->inserted)

        return -1;

    while (nb_sectors > 0) {

        if (is_changed(bs->cow_bitmap, sector_num, nb_sectors, &n)) {

            fd = bs->cow_fd;

            offset = bs->cow_sectors_offset;

        } else if (sector_num == 0 && bs->boot_sector_enabled) {

            memcpy(buf, bs->boot_sector_data, 512);

            n = 1;

            goto next;

        } else {

            fd = bs->fd;

            offset = 0;

        }

        if (fd < 0) {

            /* no file, just return empty sectors */

            memset(buf, 0, n * 512);

        } else {

            offset += sector_num * 512;

            lseek64(fd, offset, SEEK_SET);

            ret = read(fd, buf, n * 512);

            if (ret != n * 512) {

                return -1;

            }

        }

    next:

        nb_sectors -= n;

        sector_num += n;

        buf += n * 512;

    }

    return 0;

}

/* return -1 if error */

int bdrv_write(BlockDriverState *bs, int64_t sector_num, 

               const uint8_t *buf, int nb_sectors)

{

    int ret, fd, i;

    int64_t offset, retl;

    if (!bs->inserted)

        return -1;

    if (bs->read_only)

        return -1;

    if (bs->cow_bitmap) {

        fd = bs->cow_fd;

        offset = bs->cow_sectors_offset;

    } else {

        fd = bs->fd;

        offset = 0;

    }

    offset += sector_num * 512;

    retl = lseek64(fd, offset, SEEK_SET);

    if (retl == -1) {

        return -1;

    }

    ret = write(fd, buf, nb_sectors * 512);

    if (ret != nb_sectors * 512) {

        return -1;

    }

    if (bs->cow_bitmap) {

        for (i = 0; i < nb_sectors; i++)

            set_bit(bs->cow_bitmap, sector_num + i);

    }

    return 0;

}

void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr)

{

    *nb_sectors_ptr = bs->total_sectors;

}

/* force a given boot sector. */

void bdrv_set_boot_sector(BlockDriverState *bs, const uint8_t *data, int size)

{

    bs->boot_sector_enabled = 1;

    if (size > 512)

        size = 512;

    memcpy(bs->boot_sector_data, data, size);

    memset(bs->boot_sector_data + size, 0, 512 - size);

}

void bdrv_set_geometry_hint(BlockDriverState *bs, 

                            int cyls, int heads, int secs)

{

    bs->cyls = cyls;

    bs->heads = heads;

    bs->secs = secs;

}

void bdrv_set_type_hint(BlockDriverState *bs, int type)

{

    bs->type = type;

    bs->removable = ((type == BDRV_TYPE_CDROM ||

                      type == BDRV_TYPE_FLOPPY));

}

void bdrv_get_geometry_hint(BlockDriverState *bs, 

                            int *pcyls, int *pheads, int *psecs)

{

    *pcyls = bs->cyls;

    *pheads = bs->heads;

    *psecs = bs->secs;

}

int bdrv_get_type_hint(BlockDriverState *bs)

{

    return bs->type;

}

int bdrv_is_removable(BlockDriverState *bs)

{

    return bs->removable;

}

int bdrv_is_read_only(BlockDriverState *bs)

{

    return bs->read_only;

}

int bdrv_is_inserted(BlockDriverState *bs)

{

    return bs->inserted;

}

int bdrv_is_locked(BlockDriverState *bs)

{

    return bs->locked;

}

void bdrv_set_locked(BlockDriverState *bs, int locked)

{

    bs->locked = locked;

}

void bdrv_set_change_cb(BlockDriverState *bs, 

                        void (*change_cb)(void *opaque), void *opaque)

{

    bs->change_cb = change_cb;

    bs->change_opaque = opaque;

}

BlockDriverState *bdrv_find(const char *name)

{

    BlockDriverState *bs;

    for (bs = bdrv_first; bs != NULL; bs = bs->next) {

        if (!strcmp(name, bs->device_name))

            return bs;

    }

    return NULL;

}

void bdrv_info(void)

{

    BlockDriverState *bs;

    for (bs = bdrv_first; bs != NULL; bs = bs->next) {

        term_printf("%s:", bs->device_name);

        term_printf(" type=");

        switch(bs->type) {

        case BDRV_TYPE_HD:

            term_printf("hd");

            break;

        case BDRV_TYPE_CDROM:

            term_printf("cdrom");

            break;

        case BDRV_TYPE_FLOPPY:

            term_printf("floppy");

            break;

        }

        term_printf(" removable=%d", bs->removable);

        if (bs->removable) {

            term_printf(" locked=%d", bs->locked);

        }

        if (bs->inserted) {

            term_printf(" file=%s", bs->filename);

            term_printf(" ro=%d", bs->read_only);

        } else {

            term_printf(" [not inserted]");

        }

        term_printf("\n");

    }

}