xref: /external/qemu/block.c

/*
 * 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 "config-host.h"
#include "qemu-common.h"
#include "monitor/monitor.h"
#include "block/block_int.h"
#include "qemu/iov.h"
#include "qemu/module.h"
//#include "qapi/qmp/types.h"
#include "qapi/qmp/qjson.h"

#ifdef CONFIG_BSD
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/queue.h>
#ifndef __DragonFly__
#include <sys/disk.h>
#endif
#endif

#ifdef _WIN32
#include <windows.h>
#endif

static BlockDriverAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
        BlockDriverCompletionFunc *cb, void *opaque);
static BlockDriverAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
        BlockDriverCompletionFunc *cb, void *opaque);
static BlockDriverAIOCB *bdrv_aio_flush_em(BlockDriverState *bs,
        BlockDriverCompletionFunc *cb, void *opaque);
static BlockDriverAIOCB *bdrv_aio_noop_em(BlockDriverState *bs,
        BlockDriverCompletionFunc *cb, void *opaque);
static int bdrv_read_em(BlockDriverState *bs, int64_t sector_num,
                        uint8_t *buf, int nb_sectors);
static int bdrv_write_em(BlockDriverState *bs, int64_t sector_num,
                         const uint8_t *buf, int nb_sectors);

static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
    QTAILQ_HEAD_INITIALIZER(bdrv_states);

static QLIST_HEAD(, BlockDriver) bdrv_drivers =
    QLIST_HEAD_INITIALIZER(bdrv_drivers);

/* The device to use for VM snapshots */
static BlockDriverState *bs_snapshots;

/* If non-zero, use only whitelisted block drivers */
static int use_bdrv_whitelist;

int _path_is_absolute(const char *path)
{
    const char *p;
#ifdef _WIN32
    /* specific case for names like: "\\.\d:" */
    if (*path == '/' || *path == '\\')
        return 1;
#endif
    p = strchr(path, ':');
    if (p)
        p++;
    else
        p = path;
#ifdef _WIN32
    return (*p == '/' || *p == '\\');
#else
    return (*p == '/');
#endif
}

/* if filename is absolute, just copy it to dest. Otherwise, build a
   path to it by considering it is relative to base_path. URL are
   supported. */
void path_combine(char *dest, int dest_size,
                  const char *base_path,
                  const char *filename)
{
    const char *p, *p1;
    int len;

    if (dest_size <= 0)
        return;
    if (_path_is_absolute(filename)) {
        pstrcpy(dest, dest_size, filename);
    } else {
        p = strchr(base_path, ':');
        if (p)
            p++;
        else
            p = base_path;
        p1 = strrchr(base_path, '/');
#ifdef _WIN32
        {
            const char *p2;
            p2 = strrchr(base_path, '\\');
            if (!p1 || p2 > p1)
                p1 = p2;
        }
#endif
        if (p1)
            p1++;
        else
            p1 = base_path;
        if (p1 > p)
            p = p1;
        len = p - base_path;
        if (len > dest_size - 1)
            len = dest_size - 1;
        memcpy(dest, base_path, len);
        dest[len] = '\0';
        pstrcat(dest, dest_size, filename);
    }
}

void bdrv_register(BlockDriver *bdrv)
{
    if (!bdrv->bdrv_aio_readv) {
        /* add AIO emulation layer */
        bdrv->bdrv_aio_readv = bdrv_aio_readv_em;
        bdrv->bdrv_aio_writev = bdrv_aio_writev_em;
    } else if (!bdrv->bdrv_read) {
        /* add synchronous IO emulation layer */
        bdrv->bdrv_read = bdrv_read_em;
        bdrv->bdrv_write = bdrv_write_em;
    }

    if (!bdrv->bdrv_aio_flush)
        bdrv->bdrv_aio_flush = bdrv_aio_flush_em;

    QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
}

/* create a new block device (by default it is empty) */
BlockDriverState *bdrv_new(const char *device_name)
{
    BlockDriverState *bs;

    bs = g_malloc0(sizeof(BlockDriverState));
    pstrcpy(bs->device_name, sizeof(bs->device_name), device_name);
    if (device_name[0] != '\0') {
        QTAILQ_INSERT_TAIL(&bdrv_states, bs, list);
    }
    return bs;
}

BlockDriver *bdrv_find_format(const char *format_name)
{
    BlockDriver *drv1;
    QLIST_FOREACH(drv1, &bdrv_drivers, list) {
        if (!strcmp(drv1->format_name, format_name)) {
            return drv1;
        }
    }
    return NULL;
}

static int bdrv_is_whitelisted(BlockDriver *drv)
{
    static const char *whitelist[] = {
        CONFIG_BDRV_WHITELIST
    };
    const char **p;

    if (!whitelist[0])
        return 1;               /* no whitelist, anything goes */

    for (p = whitelist; *p; p++) {
        if (!strcmp(drv->format_name, *p)) {
            return 1;
        }
    }
    return 0;
}

BlockDriver *bdrv_find_whitelisted_format(const char *format_name)
{
    BlockDriver *drv = bdrv_find_format(format_name);
    return drv && bdrv_is_whitelisted(drv) ? drv : NULL;
}

int bdrv_create(BlockDriver *drv, const char* filename,
    QEMUOptionParameter *options)
{
    if (!drv->bdrv_create)
        return -ENOTSUP;

    return drv->bdrv_create(filename, options);
}

int bdrv_create_file(const char* filename, QEMUOptionParameter *options)
{
    BlockDriver *drv;

    drv = bdrv_find_protocol(filename);
    if (drv == NULL) {
        drv = bdrv_find_format("file");
    }

    return bdrv_create(drv, filename, options);
}

#ifdef _WIN32
void get_tmp_filename(char *filename, int size)
{
    char temp_dir[MAX_PATH];

    GetTempPath(MAX_PATH, temp_dir);
    GetTempFileName(temp_dir, "qem", 0, filename);
}
#else
void get_tmp_filename(char *filename, int size)
{
    int fd;
    const char *tmpdir;
    /* XXX: race condition possible */
    tmpdir = getenv("TMPDIR");
    if (!tmpdir)
        tmpdir = "/tmp";
    snprintf(filename, size, "%s/vl.XXXXXX", tmpdir);
    fd = mkstemp(filename);
    close(fd);
}
#endif

#ifdef _WIN32
static int is_windows_drive_prefix(const char *filename)
{
    return (((filename[0] >= 'a' && filename[0] <= 'z') ||
             (filename[0] >= 'A' && filename[0] <= 'Z')) &&
            filename[1] == ':');
}

int is_windows_drive(const char *filename)
{
    if (is_windows_drive_prefix(filename) &&
        filename[2] == '\0')
        return 1;
    if (strstart(filename, "\\\\.\\", NULL) ||
        strstart(filename, "//./", NULL))
        return 1;
    return 0;
}
#endif

/*
 * Detect host devices. By convention, /dev/cdrom[N] is always
 * recognized as a host CDROM.
 */
static BlockDriver *find_hdev_driver(const char *filename)
{
    int score_max = 0, score;
    BlockDriver *drv = NULL, *d;

    QLIST_FOREACH(d, &bdrv_drivers, list) {
        if (d->bdrv_probe_device) {
            score = d->bdrv_probe_device(filename);
            if (score > score_max) {
                score_max = score;
                drv = d;
            }
        }
    }

    return drv;
}

BlockDriver *bdrv_find_protocol(const char *filename)
{
    BlockDriver *drv1;
    char protocol[128];
    int len;
    const char *p;

    /* TODO Drivers without bdrv_file_open must be specified explicitly */

    /*
     * XXX(hch): we really should not let host device detection
     * override an explicit protocol specification, but moving this
     * later breaks access to device names with colons in them.
     * Thanks to the brain-dead persistent naming schemes on udev-
     * based Linux systems those actually are quite common.
     */
    drv1 = find_hdev_driver(filename);
    if (drv1) {
        return drv1;
    }

#ifdef _WIN32
     if (is_windows_drive(filename) ||
         is_windows_drive_prefix(filename))
         return bdrv_find_format("file");
#endif

    p = strchr(filename, ':');
    if (!p) {
        return bdrv_find_format("file");
    }
    len = p - filename;
    if (len > sizeof(protocol) - 1)
        len = sizeof(protocol) - 1;
    memcpy(protocol, filename, len);
    protocol[len] = '\0';
    QLIST_FOREACH(drv1, &bdrv_drivers, list) {
        if (drv1->protocol_name &&
            !strcmp(drv1->protocol_name, protocol)) {
            return drv1;
        }
    }
    return NULL;
}

static int find_image_format(const char *filename, BlockDriver **pdrv)
{
    int ret, score, score_max;
    BlockDriver *drv1, *drv;
    uint8_t buf[2048];
    BlockDriverState *bs;

    ret = bdrv_file_open(&bs, filename, 0);
    if (ret < 0) {
        *pdrv = NULL;
        return ret;
    }

    /* Return the raw BlockDriver * to scsi-generic devices or empty drives */
    if (bs->sg || !bdrv_is_inserted(bs)) {
        bdrv_delete(bs);
        drv = bdrv_find_format("raw");
        if (!drv) {
            ret = -ENOENT;
        }
        *pdrv = drv;
        return ret;
    }

    ret = bdrv_pread(bs, 0, buf, sizeof(buf));
    bdrv_delete(bs);
    if (ret < 0) {
        *pdrv = NULL;
        return ret;
    }

    score_max = 0;
    drv = NULL;
    QLIST_FOREACH(drv1, &bdrv_drivers, list) {
        if (drv1->bdrv_probe) {
            score = drv1->bdrv_probe(buf, ret, filename);
            if (score > score_max) {
                score_max = score;
                drv = drv1;
            }
        }
    }
    if (!drv) {
        ret = -ENOENT;
    }
    *pdrv = drv;
    return ret;
}

/**
 * Set the current 'total_sectors' value
 */
static int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
{
    BlockDriver *drv = bs->drv;

    /* Do not attempt drv->bdrv_getlength() on scsi-generic devices */
    if (bs->sg)
        return 0;

    /* query actual device if possible, otherwise just trust the hint */
    if (drv->bdrv_getlength) {
        int64_t length = drv->bdrv_getlength(bs);
        if (length < 0) {
            return length;
        }
        hint = length >> BDRV_SECTOR_BITS;
    }

    bs->total_sectors = hint;
    return 0;
}

/*
 * Common part for opening disk images and files
 */
static int bdrv_open_common(BlockDriverState *bs, const char *filename,
    int flags, BlockDriver *drv)
{
    int ret, open_flags;

    assert(drv != NULL);

    bs->file = NULL;
    bs->total_sectors = 0;
    bs->encrypted = 0;
    bs->valid_key = 0;
    bs->open_flags = flags;
    /* buffer_alignment defaulted to 512, drivers can change this value */
    bs->buffer_alignment = 512;

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

    if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv)) {
        return -ENOTSUP;
    }

    bs->drv = drv;
    bs->opaque = g_malloc0(drv->instance_size);

    /*
     * Yes, BDRV_O_NOCACHE aka O_DIRECT means we have to present a
     * write cache to the guest.  We do need the fdatasync to flush
     * out transactions for block allocations, and we maybe have a
     * volatile write cache in our backing device to deal with.
     */
    if (flags & (BDRV_O_CACHE_WB|BDRV_O_NOCACHE))
        bs->enable_write_cache = 1;

    /*
     * Clear flags that are internal to the block layer before opening the
     * image.
     */
    open_flags = flags & ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);

    /*
     * Snapshots should be writeable.
     */
    if (bs->is_temporary) {
        open_flags |= BDRV_O_RDWR;
    }

    /* Open the image, either directly or using a protocol */
    if (drv->bdrv_file_open) {
        ret = drv->bdrv_file_open(bs, filename, open_flags);
    } else {
        ret = bdrv_file_open(&bs->file, filename, open_flags);
        if (ret >= 0) {
            ret = drv->bdrv_open(bs, open_flags);
        }
    }

    if (ret < 0) {
        goto free_and_fail;
    }

    bs->keep_read_only = bs->read_only = !(open_flags & BDRV_O_RDWR);

    ret = refresh_total_sectors(bs, bs->total_sectors);
    if (ret < 0) {
        goto free_and_fail;
    }

#ifndef _WIN32
    if (bs->is_temporary) {
        unlink(filename);
    }
#endif
    return 0;

free_and_fail:
    if (bs->file) {
        bdrv_delete(bs->file);
        bs->file = NULL;
    }
    g_free(bs->opaque);
    bs->opaque = NULL;
    bs->drv = NULL;
    return ret;
}

/*
 * Opens a file using a protocol (file, host_device, nbd, ...)
 */
int bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags)
{
    BlockDriverState *bs;
    BlockDriver *drv;
    int ret;

    drv = bdrv_find_protocol(filename);
    if (!drv) {
        return -ENOENT;
    }

    bs = bdrv_new("");
    ret = bdrv_open_common(bs, filename, flags, drv);
    if (ret < 0) {
        bdrv_delete(bs);
        return ret;
    }
    bs->growable = 1;
    *pbs = bs;
    return 0;
}

/*
 * Opens a disk image (raw, qcow2, vmdk, ...)
 */
int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
              BlockDriver *drv)
{
    int ret;
    int probed = 0;

    if (flags & BDRV_O_SNAPSHOT) {
        BlockDriverState *bs1;
        int64_t total_size;
        int is_protocol = 0;
        BlockDriver *bdrv_qcow2;
        QEMUOptionParameter *options;
        char tmp_filename[PATH_MAX];
        char backing_filename[PATH_MAX];

        /* if snapshot, we create a temporary backing file and open it
           instead of opening 'filename' directly */

        /* if there is a backing file, use it */
        bs1 = bdrv_new("");
        ret = bdrv_open(bs1, filename, 0, drv);
        if (ret < 0) {
            bdrv_delete(bs1);
            return ret;
        }
        total_size = bdrv_getlength(bs1) & BDRV_SECTOR_MASK;

        if (bs1->drv && bs1->drv->protocol_name)
            is_protocol = 1;

        bdrv_delete(bs1);

        get_tmp_filename(tmp_filename, sizeof(tmp_filename));

        /* Real path is meaningless for protocols */
        if (is_protocol)
            snprintf(backing_filename, sizeof(backing_filename),
                     "%s", filename);
        else if (!realpath(filename, backing_filename))
            return -errno;

        bdrv_qcow2 = bdrv_find_format("qcow2");
        options = parse_option_parameters("", bdrv_qcow2->create_options, NULL);

        set_option_parameter_int(options, BLOCK_OPT_SIZE, total_size);
        set_option_parameter(options, BLOCK_OPT_BACKING_FILE, backing_filename);
        if (drv) {
            set_option_parameter(options, BLOCK_OPT_BACKING_FMT,
                drv->format_name);
        }

        ret = bdrv_create(bdrv_qcow2, tmp_filename, options);
        free_option_parameters(options);
        if (ret < 0) {
            return ret;
        }

        filename = tmp_filename;
        drv = bdrv_qcow2;
        bs->is_temporary = 1;
    }

    /* Find the right image format driver */
    if (!drv) {
        ret = find_image_format(filename, &drv);
        probed = 1;
    }

    if (!drv) {
        goto unlink_and_fail;
    }

    /* Open the image */
    ret = bdrv_open_common(bs, filename, flags, drv);
    if (ret < 0) {
        goto unlink_and_fail;
    }

    bs->probed = probed;

    /* If there is a backing file, use it */
    if ((flags & BDRV_O_NO_BACKING) == 0 && bs->backing_file[0] != '\0') {
        char backing_filename[PATH_MAX];
        int back_flags;
        BlockDriver *back_drv = NULL;

        bs->backing_hd = bdrv_new("");
        path_combine(backing_filename, sizeof(backing_filename),
                     filename, bs->backing_file);
        if (bs->backing_format[0] != '\0')
            back_drv = bdrv_find_format(bs->backing_format);

        /* backing files always opened read-only */
        back_flags =
            flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);

        ret = bdrv_open(bs->backing_hd, backing_filename, back_flags, back_drv);
        if (ret < 0) {
            bdrv_close(bs);
            return ret;
        }
        if (bs->is_temporary) {
            bs->backing_hd->keep_read_only = !(flags & BDRV_O_RDWR);
        } else {
            /* base image inherits from "parent" */
            bs->backing_hd->keep_read_only = bs->keep_read_only;
        }
    }

    if (!bdrv_key_required(bs)) {
        /* call the change callback */
        bs->media_changed = 1;
        if (bs->change_cb)
            bs->change_cb(bs->change_opaque);
    }

    return 0;

unlink_and_fail:
    if (bs->is_temporary) {
        unlink(filename);
    }
    return ret;
}

void bdrv_close(BlockDriverState *bs)
{
    if (bs->drv) {
        if (bs == bs_snapshots) {
            bs_snapshots = NULL;
        }
        if (bs->backing_hd) {
            bdrv_delete(bs->backing_hd);
            bs->backing_hd = NULL;
        }
        bs->drv->bdrv_close(bs);
        g_free(bs->opaque);
#ifdef _WIN32
        if (bs->is_temporary) {
            unlink(bs->filename);
        }
#endif
        bs->opaque = NULL;
        bs->drv = NULL;

        if (bs->file != NULL) {
            bdrv_close(bs->file);
        }

        /* call the change callback */
        bs->media_changed = 1;
        if (bs->change_cb)
            bs->change_cb(bs->change_opaque);
    }
}

void bdrv_close_all(void)
{
    BlockDriverState *bs;

    QTAILQ_FOREACH(bs, &bdrv_states, list) {
        bdrv_close(bs);
    }
}

void bdrv_delete(BlockDriverState *bs)
{
    assert(!bs->peer);

    /* remove from list, if necessary */
    if (bs->device_name[0] != '\0') {
        QTAILQ_REMOVE(&bdrv_states, bs, list);
    }

    bdrv_close(bs);
    if (bs->file != NULL) {
        bdrv_delete(bs->file);
    }

    assert(bs != bs_snapshots);
    g_free(bs);
}

int bdrv_attach(BlockDriverState *bs, DeviceState *qdev)
{
    if (bs->peer) {
        return -EBUSY;
    }
    bs->peer = qdev;
    return 0;
}

void bdrv_detach(BlockDriverState *bs, DeviceState *qdev)
{
    assert(bs->peer == qdev);
    bs->peer = NULL;
}

DeviceState *bdrv_get_attached(BlockDriverState *bs)
{
    return bs->peer;
}

/*
 * Run consistency checks on an image
 *
 * Returns 0 if the check could be completed (it doesn't mean that the image is
 * free of errors) or -errno when an internal error occured. The results of the
 * check are stored in res.
 */
int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res)
{
    if (bs->drv->bdrv_check == NULL) {
        return -ENOTSUP;
    }

    memset(res, 0, sizeof(*res));
    return bs->drv->bdrv_check(bs, res);
}

#define COMMIT_BUF_SECTORS 2048

/* commit COW file into the raw image */
int bdrv_commit(BlockDriverState *bs)
{
    BlockDriver *drv = bs->drv;
    int64_t sector, total_sectors;
    int n, ro, open_flags;
    int ret = 0, rw_ret = 0;
    uint8_t *buf;
    char filename[1024];
    BlockDriverState *bs_rw, *bs_ro;

    if (!drv)
        return -ENOMEDIUM;

    if (!bs->backing_hd) {
        return -ENOTSUP;
    }

    if (bs->backing_hd->keep_read_only) {
        return -EACCES;
    }

    ro = bs->backing_hd->read_only;
    strncpy(filename, bs->backing_hd->filename, sizeof(filename));
    open_flags =  bs->backing_hd->open_flags;

    if (ro) {
        /* re-open as RW */
        bdrv_delete(bs->backing_hd);
        bs->backing_hd = NULL;
        bs_rw = bdrv_new("");
        rw_ret = bdrv_open(bs_rw, filename, open_flags | BDRV_O_RDWR, drv);
        if (rw_ret < 0) {
            bdrv_delete(bs_rw);
            /* try to re-open read-only */
            bs_ro = bdrv_new("");
            ret = bdrv_open(bs_ro, filename, open_flags & ~BDRV_O_RDWR, drv);
            if (ret < 0) {
                bdrv_delete(bs_ro);
                /* drive not functional anymore */
                bs->drv = NULL;
                return ret;
            }
            bs->backing_hd = bs_ro;
            return rw_ret;
        }
        bs->backing_hd = bs_rw;
    }

    total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
    buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE);

    for (sector = 0; sector < total_sectors; sector += n) {
        if (drv->bdrv_is_allocated(bs, sector, COMMIT_BUF_SECTORS, &n)) {

            if (bdrv_read(bs, sector, buf, n) != 0) {
                ret = -EIO;
                goto ro_cleanup;
            }

            if (bdrv_write(bs->backing_hd, sector, buf, n) != 0) {
                ret = -EIO;
                goto ro_cleanup;
            }
        }
    }

    if (drv->bdrv_make_empty) {
        ret = drv->bdrv_make_empty(bs);
        bdrv_flush(bs);
    }

    /*
     * Make sure all data we wrote to the backing device is actually
     * stable on disk.
     */
    if (bs->backing_hd)
        bdrv_flush(bs->backing_hd);

ro_cleanup:
    g_free(buf);

    if (ro) {
        /* re-open as RO */
        bdrv_delete(bs->backing_hd);
        bs->backing_hd = NULL;
        bs_ro = bdrv_new("");
        ret = bdrv_open(bs_ro, filename, open_flags & ~BDRV_O_RDWR, drv);
        if (ret < 0) {
            bdrv_delete(bs_ro);
            /* drive not functional anymore */
            bs->drv = NULL;
            return ret;
        }
        bs->backing_hd = bs_ro;
        bs->backing_hd->keep_read_only = 0;
    }

    return ret;
}

void bdrv_commit_all(void)
{
    BlockDriverState *bs;

    QTAILQ_FOREACH(bs, &bdrv_states, list) {
        bdrv_commit(bs);
    }
}

/*
 * Return values:
 * 0        - success
 * -EINVAL  - backing format specified, but no file
 * -ENOSPC  - can't update the backing file because no space is left in the