migration-unix.c

   1 /*
   2  * QEMU live migration via Unix Domain Sockets
   3  *
   4  * Copyright Red Hat, Inc. 2009
   5  *
   6  * Authors:
   7  *  Chris Lalancette <clalance@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu-common.h"
  17 #include "qemu_socket.h"
  18 #include "migration.h"
  19 #include "qemu-char.h"
  20 #include "buffered_file.h"
  21 #include "block.h"
  22
  23 //#define DEBUG_MIGRATION_UNIX
  24
  25 #ifdef DEBUG_MIGRATION_UNIX
  26 #define DPRINTF(fmt, ...) \
  27     do { printf("migration-unix: " fmt, ## __VA_ARGS__); } while (0)
  28 #else
  29 #define DPRINTF(fmt, ...) \
  30     do { } while (0)
  31 #endif
  32
  33 static int unix_errno(MigrationState *s)
  34 {
  35     return errno;
  36 }
  37
  38 static int unix_write(MigrationState *s, const void * buf, size_t size)
  39 {
  40     return write(s->fd, buf, size);
  41 }
  42
  43 static int unix_close(MigrationState *s)
  44 {
  45     int r = 0;
  46     DPRINTF("unix_close\n");
  47     if (s->fd != -1) {
  48         if (close(s->fd) < 0) {
  49             r = -errno;
  50         }
  51         s->fd = -1;
  52     }
  53     return r;
  54 }
  55
  56 static void unix_wait_for_connect(void *opaque)
  57 {
  58     MigrationState *s = opaque;
  59     int val, ret;
  60     socklen_t valsize = sizeof(val);
  61
  62     DPRINTF("connect completed\n");
  63     do {
  64         ret = getsockopt(s->fd, SOL_SOCKET, SO_ERROR, (void *) &val, &valsize);
  65     } while (ret == -1 && errno == EINTR);
  66
  67     if (ret < 0) {
  68         migrate_fd_error(s);
  69         return;
  70     }
  71
  72     qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
  73
  74     if (val == 0)
  75         migrate_fd_connect(s);
  76     else {
  77         DPRINTF("error connecting %d\n", val);
  78         migrate_fd_error(s);
  79     }
  80 }
  81
  82 int unix_start_outgoing_migration(MigrationState *s, const char *path)
  83 {
  84     struct sockaddr_un addr;
  85     int ret;
  86
  87     addr.sun_family = AF_UNIX;
  88     snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
  89     s->get_error = unix_errno;
  90     s->write = unix_write;
  91     s->close = unix_close;
  92
  93     s->fd = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
  94     if (s->fd == -1) {
  95         DPRINTF("Unable to open socket");
  96         return -errno;
  97     }
  98
  99     socket_set_nonblock(s->fd);
 100
 101     do {
 102         ret = connect(s->fd, (struct sockaddr *)&addr, sizeof(addr));
 103         if (ret == -1) {
 104             ret = -errno;
 105         }
 106         if (ret == -EINPROGRESS || ret == -EWOULDBLOCK) {
 107             qemu_set_fd_handler2(s->fd, NULL, NULL, unix_wait_for_connect, s);
 108             return 0;
 109         }
 110     } while (ret == -EINTR);
 111
 112     if (ret < 0) {
 113         DPRINTF("connect failed\n");
 114         migrate_fd_error(s);
 115         return ret;
 116     }
 117     migrate_fd_connect(s);
 118     return 0;
 119 }
 120
 121 static void unix_accept_incoming_migration(void *opaque)
 122 {
 123     struct sockaddr_un addr;
 124     socklen_t addrlen = sizeof(addr);
 125     int s = (intptr_t)opaque;
 126     QEMUFile *f;
 127     int c;
 128
 129     do {
 130         c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
 131     } while (c == -1 && errno == EINTR);
 132
 133     DPRINTF("accepted migration\n");
 134
 135     if (c == -1) {
 136         fprintf(stderr, "could not accept migration connection\n");
 137         goto out2;
 138     }
 139
 140     f = qemu_fopen_socket(c);
 141     if (f == NULL) {
 142         fprintf(stderr, "could not qemu_fopen socket\n");
 143         goto out;
 144     }
 145
 146     process_incoming_migration(f);
 147     qemu_fclose(f);
 148 out:
 149     close(c);
 150 out2:
 151     qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
 152     close(s);
 153 }
 154
 155 int unix_start_incoming_migration(const char *path)
 156 {
 157     struct sockaddr_un addr;
 158     int s;
 159     int ret;
 160
 161     DPRINTF("Attempting to start an incoming migration\n");
 162
 163     s = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
 164     if (s == -1) {
 165         fprintf(stderr, "Could not open unix socket: %s\n", strerror(errno));
 166         return -errno;
 167     }
 168
 169     memset(&addr, 0, sizeof(addr));
 170     addr.sun_family = AF_UNIX;
 171     snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
 172
 173     unlink(addr.sun_path);
 174     if (bind(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
 175         ret = -errno;
 176         fprintf(stderr, "bind(unix:%s): %s\n", addr.sun_path, strerror(errno));
 177         goto err;
 178     }
 179     if (listen(s, 1) == -1) {
 180         fprintf(stderr, "listen(unix:%s): %s\n", addr.sun_path,
 181                 strerror(errno));
 182         ret = -errno;
 183         goto err;
 184     }
 185
 186     qemu_set_fd_handler2(s, NULL, unix_accept_incoming_migration, NULL,
 187                          (void *)(intptr_t)s);
 188
 189     return 0;
 190
 191 err:
 192     close(s);
 193     return ret;
 194 }