Archipelago » qemu

/*

 * QEMU Block driver for  NBD

 *

 * Copyright (C) 2008 Bull S.A.S.

 *     Author: Laurent Vivier <Laurent.Vivier@bull.net>

 *

 * Some parts:

 *    Copyright (C) 2007 Anthony Liguori <anthony@codemonkey.ws>

 *

 * 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 "nbd.h"

#include "module.h"

#include "qemu_socket.h"

#include <sys/types.h>

#include <unistd.h>

#define EN_OPTSTR ":exportname="

/* #define DEBUG_NBD */

#if defined(DEBUG_NBD)

#define logout(fmt, ...) \

                fprintf(stderr, "nbd\t%-24s" fmt, __func__, ##__VA_ARGS__)

#else

#define logout(fmt, ...) ((void)0)

#endif

typedef struct BDRVNBDState {

    int sock;

    off_t size;

    size_t blocksize;

    char *export_name; /* An NBD server may export several devices */

    /* If it begins with  '/', this is a UNIX domain socket. Otherwise,

     * it's a string of the form <hostname|ip4|\[ip6\]>:port

     */

    char *host_spec;

} BDRVNBDState;

static int nbd_config(BDRVNBDState *s, const char *filename, int flags)

{

    char *file;

    char *export_name;

    const char *host_spec;

    const char *unixpath;

    int err = -EINVAL;

    file = g_strdup(filename);

    export_name = strstr(file, EN_OPTSTR);

    if (export_name) {

        if (export_name[strlen(EN_OPTSTR)] == 0) {

            goto out;

        }

        export_name[0] = 0; /* truncate 'file' */

        export_name += strlen(EN_OPTSTR);

        s->export_name = g_strdup(export_name);

    }

    /* extract the host_spec - fail if it's not nbd:... */

    if (!strstart(file, "nbd:", &host_spec)) {

        goto out;

    }

    /* are we a UNIX or TCP socket? */

    if (strstart(host_spec, "unix:", &unixpath)) {

        if (unixpath[0] != '/') { /* We demand  an absolute path*/

            goto out;

        }

        s->host_spec = g_strdup(unixpath);

    } else {

        s->host_spec = g_strdup(host_spec);

    }

    err = 0;

out:

    g_free(file);

    if (err != 0) {

        g_free(s->export_name);

        g_free(s->host_spec);

    }

    return err;

}

static int nbd_establish_connection(BlockDriverState *bs)

{

    BDRVNBDState *s = bs->opaque;

    int sock;

    int ret;

    off_t size;

    size_t blocksize;

    uint32_t nbdflags;

    if (s->host_spec[0] == '/') {

        sock = unix_socket_outgoing(s->host_spec);

    } else {

        sock = tcp_socket_outgoing_spec(s->host_spec);

    }

    /* Failed to establish connection */

    if (sock == -1) {

        logout("Failed to establish connection to NBD server\n");

        return -errno;

    }

    /* NBD handshake */

    ret = nbd_receive_negotiate(sock, s->export_name, &nbdflags, &size,

                                &blocksize);

    if (ret == -1) {

        logout("Failed to negotiate with the NBD server\n");

        closesocket(sock);

        return -errno;

    }

    /* Now that we're connected, set the socket to be non-blocking */

    socket_set_nonblock(sock);

    s->sock = sock;

    s->size = size;

    s->blocksize = blocksize;

    logout("Established connection with NBD server\n");

    return 0;

}

static void nbd_teardown_connection(BlockDriverState *bs)

{

    BDRVNBDState *s = bs->opaque;

    struct nbd_request request;

    request.type = NBD_CMD_DISC;

    request.handle = (uint64_t)(intptr_t)bs;

    request.from = 0;

    request.len = 0;

    nbd_send_request(s->sock, &request);

    closesocket(s->sock);

}

static int nbd_open(BlockDriverState *bs, const char* filename, int flags)

{

    BDRVNBDState *s = bs->opaque;

    int result;

    /* Pop the config into our state object. Exit if invalid. */

    result = nbd_config(s, filename, flags);

    if (result != 0) {

        return result;

    }

    /* establish TCP connection, return error if it fails

     * TODO: Configurable retry-until-timeout behaviour.

     */

    result = nbd_establish_connection(bs);

    return result;

}

static int nbd_read(BlockDriverState *bs, int64_t sector_num,

                    uint8_t *buf, int nb_sectors)

{

    BDRVNBDState *s = bs->opaque;

    struct nbd_request request;

    struct nbd_reply reply;

    request.type = NBD_CMD_READ;

    request.handle = (uint64_t)(intptr_t)bs;

    request.from = sector_num * 512;;

    request.len = nb_sectors * 512;

    if (nbd_send_request(s->sock, &request) == -1)

        return -errno;

    if (nbd_receive_reply(s->sock, &reply) == -1)

        return -errno;

    if (reply.error !=0)

        return -reply.error;

    if (reply.handle != request.handle)

        return -EIO;

    if (nbd_wr_sync(s->sock, buf, request.len, 1) != request.len)

        return -EIO;

    return 0;

}

static int nbd_write(BlockDriverState *bs, int64_t sector_num,

                     const uint8_t *buf, int nb_sectors)

{

    BDRVNBDState *s = bs->opaque;

    struct nbd_request request;

    struct nbd_reply reply;

    request.type = NBD_CMD_WRITE;

    request.handle = (uint64_t)(intptr_t)bs;

    request.from = sector_num * 512;;

    request.len = nb_sectors * 512;

    if (nbd_send_request(s->sock, &request) == -1)

        return -errno;

    if (nbd_wr_sync(s->sock, (uint8_t*)buf, request.len, 0) != request.len)

        return -EIO;

    if (nbd_receive_reply(s->sock, &reply) == -1)

        return -errno;

    if (reply.error !=0)

        return -reply.error;

    if (reply.handle != request.handle)

        return -EIO;

    return 0;

}

static void nbd_close(BlockDriverState *bs)

{

    BDRVNBDState *s = bs->opaque;

    g_free(s->export_name);

    g_free(s->host_spec);

    nbd_teardown_connection(bs);

}

static int64_t nbd_getlength(BlockDriverState *bs)

{

    BDRVNBDState *s = bs->opaque;

    return s->size;

}

static BlockDriver bdrv_nbd = {

    .format_name        = "nbd",

    .instance_size        = sizeof(BDRVNBDState),

    .bdrv_file_open        = nbd_open,

    .bdrv_read                = nbd_read,

    .bdrv_write                = nbd_write,

    .bdrv_close                = nbd_close,

    .bdrv_getlength        = nbd_getlength,

    .protocol_name        = "nbd",

};

static void bdrv_nbd_init(void)

{

    bdrv_register(&bdrv_nbd);

}

block_init(bdrv_nbd_init);