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* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; under version 2 of the License.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#include <qemu-common.h>
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#include "block_int.h"
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netinet/tcp.h>
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#include <arpa/inet.h>
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#define SOCKET_PATH "/var/lock/qemu-nbd-%s"
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#define NBD_BUFFER_SIZE (1024*1024)
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static void usage(const char *name)
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"Usage: %s [OPTIONS] FILE\n"
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"QEMU Disk Network Block Device Server\n"
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" -p, --port=PORT port to listen on (default `1024')\n"
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" -o, --offset=OFFSET offset into the image\n"
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" -b, --bind=IFACE interface to bind to (default `0.0.0.0')\n"
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" -k, --socket=PATH path to the unix socket\n"
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" (default '"SOCKET_PATH"')\n"
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" -r, --read-only export read-only\n"
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" -P, --partition=NUM only expose partition NUM\n"
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" -s, --snapshot use snapshot file\n"
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" -n, --nocache disable host cache\n"
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" -c, --connect=DEV connect FILE to the local NBD device DEV\n"
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" -d, --disconnect disconnect the specified device\n"
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" -e, --shared=NUM device can be shared by NUM clients (default '1')\n"
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" -t, --persistent don't exit on the last connection\n"
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" -v, --verbose display extra debugging information\n"
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" -h, --help display this help and exit\n"
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" -V, --version output version information and exit\n"
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"Report bugs to <anthony@codemonkey.ws>\n"
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static void version(const char *name)
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"Written by Anthony Liguori.\n"
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"Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.\n"
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"This is free software; see the source for copying conditions. There is NO\n"
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"warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
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struct partition_record
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uint32_t start_cylinder;
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uint32_t start_sector_abs;
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uint32_t nb_sectors_abs;
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static void read_partition(uint8_t *p, struct partition_record *r)
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r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
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r->start_sector = p[2] & 0x3f;
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r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
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r->end_sector = p[6] & 0x3f;
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r->start_sector_abs = p[8] | p[9] << 8 | p[10] << 16 | p[11] << 24;
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r->nb_sectors_abs = p[12] | p[13] << 8 | p[14] << 16 | p[15] << 24;
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static int find_partition(BlockDriverState *bs, int partition,
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off_t *offset, off_t *size)
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struct partition_record mbr[4];
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if (bdrv_read(bs, 0, data, 1))
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errx(EINVAL, "error while reading");
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if (data[510] != 0x55 || data[511] != 0xaa) {
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for (i = 0; i < 4; i++) {
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read_partition(&data[446 + 16 * i], &mbr[i]);
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if (!mbr[i].nb_sectors_abs)
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if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
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struct partition_record ext[4];
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if (bdrv_read(bs, mbr[i].start_sector_abs, data1, 1))
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errx(EINVAL, "error while reading");
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for (j = 0; j < 4; j++) {
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read_partition(&data1[446 + 16 * j], &ext[j]);
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if (!ext[j].nb_sectors_abs)
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if ((ext_partnum + j + 1) == partition) {
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*offset = (uint64_t)ext[j].start_sector_abs << 9;
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*size = (uint64_t)ext[j].nb_sectors_abs << 9;
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} else if ((i + 1) == partition) {
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*offset = (uint64_t)mbr[i].start_sector_abs << 9;
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*size = (uint64_t)mbr[i].nb_sectors_abs << 9;
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static void show_parts(const char *device)
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/* linux just needs an open() to trigger
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* the partition table update
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* but remember to load the module with max_part != 0 :
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* modprobe nbd max_part=63
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nbd = open(device, O_RDWR);
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int main(int argc, char **argv)
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BlockDriverState *bs;
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off_t dev_offset = 0;
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bool readonly = false;
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bool disconnect = false;
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const char *bindto = "0.0.0.0";
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struct sockaddr_in addr;
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socklen_t addr_len = sizeof(addr);
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const char *sopt = "hVbo:p:rsnP:c:dvk:e:t";
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struct option lopt[] = {
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{ "help", 0, 0, 'h' },
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{ "version", 0, 0, 'V' },
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{ "bind", 1, 0, 'b' },
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{ "port", 1, 0, 'p' },
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{ "socket", 1, 0, 'k' },
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{ "offset", 1, 0, 'o' },
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{ "read-only", 0, 0, 'r' },
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{ "partition", 1, 0, 'P' },
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{ "connect", 1, 0, 'c' },
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{ "disconnect", 0, 0, 'd' },
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{ "snapshot", 0, 0, 's' },
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{ "nocache", 0, 0, 'n' },
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{ "shared", 1, 0, 'e' },
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{ "persistent", 0, 0, 't' },
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{ "verbose", 0, 0, 'v' },
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while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
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flags |= BDRV_O_SNAPSHOT;
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flags |= BDRV_O_NOCACHE;
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li = strtol(optarg, &end, 0);
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errx(EINVAL, "Invalid port `%s'", optarg);
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if (li < 1 || li > 65535) {
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errx(EINVAL, "Port out of range `%s'", optarg);
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dev_offset = strtoll (optarg, &end, 0);
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errx(EINVAL, "Invalid offset `%s'", optarg);
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if (dev_offset < 0) {
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errx(EINVAL, "Offset must be positive `%s'", optarg);
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partition = strtol(optarg, &end, 0);
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errx(EINVAL, "Invalid partition `%s'", optarg);
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if (partition < 1 || partition > 8)
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errx(EINVAL, "Invalid partition %d", partition);
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if (socket[0] != '/')
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errx(EINVAL, "socket path must be absolute\n");
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shared = strtol(optarg, &end, 0);
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errx(EINVAL, "Invalid shared device number '%s'", optarg);
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errx(EINVAL, "Shared device number must be greater than 0\n");
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errx(EINVAL, "Try `%s --help' for more information.",
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if ((argc - optind) != 1) {
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errx(EINVAL, "Invalid number of argument.\n"
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"Try `%s --help' for more information.",
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fd = open(argv[optind], O_RDWR);
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errx(errno, "Cannot open %s", argv[optind]);
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printf("%s disconnected\n", argv[optind]);
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bs = bdrv_new("hda");
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if (bdrv_open(bs, argv[optind], flags) == -1)
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fd_size = bs->total_sectors * 512;
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if (partition != -1 &&
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find_partition(bs, partition, &dev_offset, &fd_size))
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errx(errno, "Could not find partition %d", partition);
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daemon(0, 0); /* detach client and server */
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if (socket == NULL) {
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sprintf(sockpath, SOCKET_PATH, basename(device));
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sock = unix_socket_outgoing(socket);
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if (errno != ENOENT && errno != ECONNREFUSED)
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sleep(1); /* wait children */
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} while (sock == -1);
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fd = open(device, O_RDWR);
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ret = nbd_receive_negotiate(sock, &size, &blocksize);
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ret = nbd_init(fd, sock, size, blocksize);
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printf("NBD device %s is now connected to file %s\n",
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device, argv[optind]);
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/* update partition table */
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nbd_client(fd, sock);
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sharing_fds = qemu_malloc((shared + 1) * sizeof(int));
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if (sharing_fds == NULL)
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errx(ENOMEM, "Cannot allocate sharing fds");
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sharing_fds[0] = unix_socket_incoming(socket);
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sharing_fds[0] = tcp_socket_incoming(bindto, port);
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if (sharing_fds[0] == -1)
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max_fd = sharing_fds[0];
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data = qemu_memalign(512, NBD_BUFFER_SIZE);
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errx(ENOMEM, "Cannot allocate data buffer");
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for (i = 0; i < nb_fds; i++)
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FD_SET(sharing_fds[i], &fds);
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ret = select(max_fd + 1, &fds, NULL, NULL, NULL);
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if (FD_ISSET(sharing_fds[0], &fds))
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for (i = 1; i < nb_fds && ret; i++) {
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if (FD_ISSET(sharing_fds[i], &fds)) {
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if (nbd_trip(bs, sharing_fds[i], fd_size, dev_offset,
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&offset, readonly, data, NBD_BUFFER_SIZE) != 0) {
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close(sharing_fds[i]);
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sharing_fds[i] = sharing_fds[nb_fds];
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/* new connection ? */
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if (FD_ISSET(sharing_fds[0], &fds)) {
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if (nb_fds < shared + 1) {
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sharing_fds[nb_fds] = accept(sharing_fds[0],
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(struct sockaddr *)&addr,
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if (sharing_fds[nb_fds] != -1 &&
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nbd_negotiate(sharing_fds[nb_fds], fd_size) != -1) {
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if (sharing_fds[nb_fds] > max_fd)
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max_fd = sharing_fds[nb_fds];
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} while (persistent || nb_fds > 1);
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close(sharing_fds[0]);
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qemu_free(sharing_fds);
added
removed
qemu-nbd.c
