Archipelago » qemu

/*

 *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>

 *

 *  Network Block Device

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; under version 2 of the License.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program; if not, see <http://www.gnu.org/licenses/>.

 */

#include "qemu-common.h"

#include "block/block.h"

#include "block/nbd.h"

#include <stdarg.h>

#include <stdio.h>

#include <getopt.h>

#include <err.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <netinet/tcp.h>

#include <arpa/inet.h>

#include <signal.h>

#include <libgen.h>

#include <pthread.h>

#define SOCKET_PATH          "/var/lock/qemu-nbd-%s"

#define QEMU_NBD_OPT_CACHE   1

#define QEMU_NBD_OPT_AIO     2

#define QEMU_NBD_OPT_DISCARD 3

static NBDExport *exp;

static int verbose;

static char *srcpath;

static char *sockpath;

static int persistent = 0;

static enum { RUNNING, TERMINATE, TERMINATING, TERMINATED } state;

static int shared = 1;

static int nb_fds;

static void usage(const char *name)

{

    (printf) (

"Usage: %s [OPTIONS] FILE\n"

"QEMU Disk Network Block Device Server\n"

"\n"

"  -h, --help           display this help and exit\n"

"  -V, --version        output version information and exit\n"

"\n"

"Connection properties:\n"

"  -p, --port=PORT      port to listen on (default `%d')\n"

"  -b, --bind=IFACE     interface to bind to (default `0.0.0.0')\n"

"  -k, --socket=PATH    path to the unix socket\n"

"                       (default '"SOCKET_PATH"')\n"

"  -e, --shared=NUM     device can be shared by NUM clients (default '1')\n"

"  -t, --persistent     don't exit on the last connection\n"

"  -v, --verbose        display extra debugging information\n"

"\n"

"Exposing part of the image:\n"

"  -o, --offset=OFFSET  offset into the image\n"

"  -P, --partition=NUM  only expose partition NUM\n"

"\n"

#ifdef __linux__

"Kernel NBD client support:\n"

"  -c, --connect=DEV    connect FILE to the local NBD device DEV\n"

"  -d, --disconnect     disconnect the specified device\n"

"\n"

#endif

"\n"

"Block device options:\n"

"  -r, --read-only      export read-only\n"

"  -s, --snapshot       use snapshot file\n"

"  -n, --nocache        disable host cache\n"

"      --cache=MODE     set cache mode (none, writeback, ...)\n"

#ifdef CONFIG_LINUX_AIO

"      --aio=MODE       set AIO mode (native or threads)\n"

#endif

"\n"

"Report bugs to <qemu-devel@nongnu.org>\n"

    , name, NBD_DEFAULT_PORT, "DEVICE");

}

static void version(const char *name)

{

    printf(

"%s version 0.0.1\n"

"Written by Anthony Liguori.\n"

"\n"

"Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.\n"

"This is free software; see the source for copying conditions.  There is NO\n"

"warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"

    , name);

}

struct partition_record

{

    uint8_t bootable;

    uint8_t start_head;

    uint32_t start_cylinder;

    uint8_t start_sector;

    uint8_t system;

    uint8_t end_head;

    uint8_t end_cylinder;

    uint8_t end_sector;

    uint32_t start_sector_abs;

    uint32_t nb_sectors_abs;

};

static void read_partition(uint8_t *p, struct partition_record *r)

{

    r->bootable = p[0];

    r->start_head = p[1];

    r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);

    r->start_sector = p[2] & 0x3f;

    r->system = p[4];

    r->end_head = p[5];

    r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);

    r->end_sector = p[6] & 0x3f;

    r->start_sector_abs = p[8] | p[9] << 8 | p[10] << 16 | p[11] << 24;

    r->nb_sectors_abs = p[12] | p[13] << 8 | p[14] << 16 | p[15] << 24;

}

static int find_partition(BlockDriverState *bs, int partition,

                          off_t *offset, off_t *size)

{

    struct partition_record mbr[4];

    uint8_t data[512];

    int i;

    int ext_partnum = 4;

    int ret;

    if ((ret = bdrv_read(bs, 0, data, 1)) < 0) {

        errno = -ret;

        err(EXIT_FAILURE, "error while reading");

    }

    if (data[510] != 0x55 || data[511] != 0xaa) {

        return -EINVAL;

    }

    for (i = 0; i < 4; i++) {

        read_partition(&data[446 + 16 * i], &mbr[i]);

        if (!mbr[i].nb_sectors_abs)

            continue;

        if (mbr[i].system == 0xF || mbr[i].system == 0x5) {

            struct partition_record ext[4];

            uint8_t data1[512];

            int j;

            if ((ret = bdrv_read(bs, mbr[i].start_sector_abs, data1, 1)) < 0) {

                errno = -ret;

                err(EXIT_FAILURE, "error while reading");

            }

            for (j = 0; j < 4; j++) {

                read_partition(&data1[446 + 16 * j], &ext[j]);

                if (!ext[j].nb_sectors_abs)

                    continue;

                if ((ext_partnum + j + 1) == partition) {

                    *offset = (uint64_t)ext[j].start_sector_abs << 9;

                    *size = (uint64_t)ext[j].nb_sectors_abs << 9;

                    return 0;

                }

            }

            ext_partnum += 4;

        } else if ((i + 1) == partition) {

            *offset = (uint64_t)mbr[i].start_sector_abs << 9;

            *size = (uint64_t)mbr[i].nb_sectors_abs << 9;

            return 0;

        }

    }

    return -ENOENT;

}

static void termsig_handler(int signum)

{

    state = TERMINATE;

    qemu_notify_event();

}

static void *show_parts(void *arg)

{

    char *device = arg;

    int nbd;

    /* linux just needs an open() to trigger

     * the partition table update

     * but remember to load the module with max_part != 0 :

     *     modprobe nbd max_part=63

     */

    nbd = open(device, O_RDWR);

    if (nbd >= 0) {

        close(nbd);

    }

    return NULL;

}

static void *nbd_client_thread(void *arg)

{

    char *device = arg;

    off_t size;

    size_t blocksize;

    uint32_t nbdflags;

    int fd, sock;

    int ret;

    pthread_t show_parts_thread;

    sock = unix_socket_outgoing(sockpath);

    if (sock < 0) {

        goto out;

    }

    ret = nbd_receive_negotiate(sock, NULL, &nbdflags,

                                &size, &blocksize);

    if (ret < 0) {

        goto out;

    }

    fd = open(device, O_RDWR);

    if (fd < 0) {

        /* Linux-only, we can use %m in printf.  */

        fprintf(stderr, "Failed to open %s: %m", device);

        goto out;

    }

    ret = nbd_init(fd, sock, nbdflags, size, blocksize);

    if (ret < 0) {

        goto out;

    }

    /* update partition table */

    pthread_create(&show_parts_thread, NULL, show_parts, device);

    if (verbose) {

        fprintf(stderr, "NBD device %s is now connected to %s\n",

                device, srcpath);

    } else {

        /* Close stderr so that the qemu-nbd process exits.  */

        dup2(STDOUT_FILENO, STDERR_FILENO);

    }

    ret = nbd_client(fd);

    if (ret) {

        goto out;

    }

    close(fd);

    kill(getpid(), SIGTERM);

    return (void *) EXIT_SUCCESS;

out:

    kill(getpid(), SIGTERM);

    return (void *) EXIT_FAILURE;

}

static int nbd_can_accept(void *opaque)

{

    return nb_fds < shared;

}

static void nbd_export_closed(NBDExport *exp)

{

    assert(state == TERMINATING);

    state = TERMINATED;

}

static void nbd_client_closed(NBDClient *client)

{

    nb_fds--;

    if (nb_fds == 0 && !persistent && state == RUNNING) {

        state = TERMINATE;

    }

    qemu_notify_event();

    nbd_client_put(client);

}

static void nbd_accept(void *opaque)

{

    int server_fd = (uintptr_t) opaque;

    struct sockaddr_in addr;

    socklen_t addr_len = sizeof(addr);

    int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);

    if (state >= TERMINATE) {

        close(fd);

        return;

    }

    if (fd >= 0 && nbd_client_new(exp, fd, nbd_client_closed)) {

        nb_fds++;

    }

}

int main(int argc, char **argv)

{

    BlockDriverState *bs;

    off_t dev_offset = 0;

    uint32_t nbdflags = 0;

    bool disconnect = false;

    const char *bindto = "0.0.0.0";

    char *device = NULL;

    int port = NBD_DEFAULT_PORT;

    off_t fd_size;

    const char *sopt = "hVb:o:p:rsnP:c:dvk:e:t";

    struct option lopt[] = {

        { "help", 0, NULL, 'h' },

        { "version", 0, NULL, 'V' },

        { "bind", 1, NULL, 'b' },

        { "port", 1, NULL, 'p' },

        { "socket", 1, NULL, 'k' },

        { "offset", 1, NULL, 'o' },

        { "read-only", 0, NULL, 'r' },

        { "partition", 1, NULL, 'P' },

        { "connect", 1, NULL, 'c' },

        { "disconnect", 0, NULL, 'd' },

        { "snapshot", 0, NULL, 's' },

        { "nocache", 0, NULL, 'n' },

        { "cache", 1, NULL, QEMU_NBD_OPT_CACHE },

#ifdef CONFIG_LINUX_AIO

        { "aio", 1, NULL, QEMU_NBD_OPT_AIO },

#endif

        { "discard", 1, NULL, QEMU_NBD_OPT_DISCARD },

        { "shared", 1, NULL, 'e' },

        { "persistent", 0, NULL, 't' },

        { "verbose", 0, NULL, 'v' },

        { NULL, 0, NULL, 0 }

    };

    int ch;

    int opt_ind = 0;

    int li;

    char *end;

    int flags = BDRV_O_RDWR;

    int partition = -1;

    int ret;

    int fd;

    bool seen_cache = false;

    bool seen_discard = false;

#ifdef CONFIG_LINUX_AIO

    bool seen_aio = false;

#endif

    pthread_t client_thread;

    /* The client thread uses SIGTERM to interrupt the server.  A signal

     * handler ensures that "qemu-nbd -v -c" exits with a nice status code.

     */

    struct sigaction sa_sigterm;

    memset(&sa_sigterm, 0, sizeof(sa_sigterm));

    sa_sigterm.sa_handler = termsig_handler;

    sigaction(SIGTERM, &sa_sigterm, NULL);

    while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {

        switch (ch) {

        case 's':

            flags |= BDRV_O_SNAPSHOT;

            break;

        case 'n':

            optarg = (char *) "none";

            /* fallthrough */

        case QEMU_NBD_OPT_CACHE:

            if (seen_cache) {

                errx(EXIT_FAILURE, "-n and --cache can only be specified once");

            }

            seen_cache = true;

            if (bdrv_parse_cache_flags(optarg, &flags) == -1) {

                errx(EXIT_FAILURE, "Invalid cache mode `%s'", optarg);

            }

            break;

#ifdef CONFIG_LINUX_AIO

        case QEMU_NBD_OPT_AIO:

            if (seen_aio) {

                errx(EXIT_FAILURE, "--aio can only be specified once");

            }

            seen_aio = true;

            if (!strcmp(optarg, "native")) {

                flags |= BDRV_O_NATIVE_AIO;

            } else if (!strcmp(optarg, "threads")) {

                /* this is the default */

            } else {

               errx(EXIT_FAILURE, "invalid aio mode `%s'", optarg);

            }

            break;

#endif

        case QEMU_NBD_OPT_DISCARD:

            if (seen_discard) {

                errx(EXIT_FAILURE, "--discard can only be specified once");

            }

            seen_discard = true;

            if (bdrv_parse_discard_flags(optarg, &flags) == -1) {

                errx(EXIT_FAILURE, "Invalid discard mode `%s'", optarg);

            }

            break;

        case 'b':

            bindto = optarg;

            break;

        case 'p':

            li = strtol(optarg, &end, 0);

            if (*end) {

                errx(EXIT_FAILURE, "Invalid port `%s'", optarg);

            }

            if (li < 1 || li > 65535) {

                errx(EXIT_FAILURE, "Port out of range `%s'", optarg);

            }

            port = (uint16_t)li;

            break;

        case 'o':

                dev_offset = strtoll (optarg, &end, 0);

            if (*end) {

                errx(EXIT_FAILURE, "Invalid offset `%s'", optarg);

            }

            if (dev_offset < 0) {

                errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);

            }

            break;

        case 'r':

            nbdflags |= NBD_FLAG_READ_ONLY;

            flags &= ~BDRV_O_RDWR;

            break;

        case 'P':

            partition = strtol(optarg, &end, 0);

            if (*end)

                errx(EXIT_FAILURE, "Invalid partition `%s'", optarg);

            if (partition < 1 || partition > 8)

                errx(EXIT_FAILURE, "Invalid partition %d", partition);

            break;

        case 'k':

            sockpath = optarg;

            if (sockpath[0] != '/')

                errx(EXIT_FAILURE, "socket path must be absolute\n");

            break;

        case 'd':

            disconnect = true;

            break;

        case 'c':

            device = optarg;

            break;

        case 'e':

            shared = strtol(optarg, &end, 0);

            if (*end) {

                errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg);

            }

            if (shared < 1) {

                errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");

            }

            break;

        case 't':

            persistent = 1;

            break;

        case 'v':

            verbose = 1;

            break;

        case 'V':

            version(argv[0]);

            exit(0);

            break;

        case 'h':

            usage(argv[0]);

            exit(0);

            break;

        case '?':

            errx(EXIT_FAILURE, "Try `%s --help' for more information.",

                 argv[0]);

        }

    }

    if ((argc - optind) != 1) {

        errx(EXIT_FAILURE, "Invalid number of argument.\n"

             "Try `%s --help' for more information.",

             argv[0]);

    }

    if (disconnect) {

        fd = open(argv[optind], O_RDWR);

        if (fd < 0) {

            err(EXIT_FAILURE, "Cannot open %s", argv[optind]);

        }

        nbd_disconnect(fd);

        close(fd);

        printf("%s disconnected\n", argv[optind]);

        return 0;

    }

    if (device && !verbose) {

        int stderr_fd[2];

        pid_t pid;

        int ret;

        if (qemu_pipe(stderr_fd) < 0) {

            err(EXIT_FAILURE, "Error setting up communication pipe");

        }

        /* Now daemonize, but keep a communication channel open to

         * print errors and exit with the proper status code.

         */

        pid = fork();

        if (pid == 0) {

            close(stderr_fd[0]);

            ret = qemu_daemon(1, 0);

            /* Temporarily redirect stderr to the parent's pipe...  */

            dup2(stderr_fd[1], STDERR_FILENO);

            if (ret < 0) {

                err(EXIT_FAILURE, "Failed to daemonize");

            }

            /* ... close the descriptor we inherited and go on.  */

            close(stderr_fd[1]);

        } else {

            bool errors = false;

            char *buf;

            /* In the parent.  Print error messages from the child until

             * it closes the pipe.

             */

            close(stderr_fd[1]);

            buf = g_malloc(1024);

            while ((ret = read(stderr_fd[0], buf, 1024)) > 0) {

                errors = true;

                ret = qemu_write_full(STDERR_FILENO, buf, ret);

                if (ret < 0) {

                    exit(EXIT_FAILURE);

                }

            }

            if (ret < 0) {

                err(EXIT_FAILURE, "Cannot read from daemon");

            }

            /* Usually the daemon should not print any message.

             * Exit with zero status in that case.

             */

            exit(errors);

        }

    }

    if (device != NULL && sockpath == NULL) {

        sockpath = g_malloc(128);

        snprintf(sockpath, 128, SOCKET_PATH, basename(device));

    }

    qemu_init_main_loop();

    bdrv_init();

    atexit(bdrv_close_all);

    bs = bdrv_new("hda");

    srcpath = argv[optind];

    if ((ret = bdrv_open(bs, srcpath, NULL, flags, NULL)) < 0) {

        errno = -ret;

        err(EXIT_FAILURE, "Failed to bdrv_open '%s'", argv[optind]);

    }

    fd_size = bdrv_getlength(bs);

    if (partition != -1) {

        ret = find_partition(bs, partition, &dev_offset, &fd_size);

        if (ret < 0) {

            errno = -ret;

            err(EXIT_FAILURE, "Could not find partition %d", partition);

        }

    }

    exp = nbd_export_new(bs, dev_offset, fd_size, nbdflags, nbd_export_closed);

    if (sockpath) {

        fd = unix_socket_incoming(sockpath);

    } else {

        fd = tcp_socket_incoming(bindto, port);

    }

    if (fd < 0) {

        return 1;

    }

    if (device) {

        int ret;

        ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);

        if (ret != 0) {

            errx(EXIT_FAILURE, "Failed to create client thread: %s",

                 strerror(ret));

        }

    } else {

        /* Shut up GCC warnings.  */

        memset(&client_thread, 0, sizeof(client_thread));

    }

    qemu_set_fd_handler2(fd, nbd_can_accept, nbd_accept, NULL,

                         (void *)(uintptr_t)fd);

    /* now when the initialization is (almost) complete, chdir("/")

     * to free any busy filesystems */

    if (chdir("/") < 0) {

        err(EXIT_FAILURE, "Could not chdir to root directory");

    }

    state = RUNNING;

    do {

        main_loop_wait(false);

        if (state == TERMINATE) {

            state = TERMINATING;

            nbd_export_close(exp);

            nbd_export_put(exp);

            exp = NULL;

        }

    } while (state != TERMINATED);

    bdrv_close(bs);

    if (sockpath) {

        unlink(sockpath);

    }

    if (device) {

        void *ret;

        pthread_join(client_thread, &ret);

        exit(ret != NULL);

    } else {

        exit(EXIT_SUCCESS);

    }

}