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  */
  13
  14 #include "qemu-common.h"
  15 #include "qemu_socket.h"
  16 #include "migration.h"
  17 #include "qemu-char.h"
  18 #include "buffered_file.h"
  19 #include "block.h"
  20
  21 //#define DEBUG_MIGRATION_UNIX
  22
  23 #ifdef DEBUG_MIGRATION_UNIX
  24 #define DPRINTF(fmt, ...) \
  25     do { printf("migration-unix: " fmt, ## __VA_ARGS__); } while (0)
  26 #else
  27 #define DPRINTF(fmt, ...) \
  28     do { } while (0)
  29 #endif
  30
  31 static int unix_errno(MigrationState *s)
  32 {
  33     return errno;
  34 }
  35
  36 static int unix_write(MigrationState *s, const void * buf, size_t size)
  37 {
  38     return write(s->fd, buf, size);
  39 }
  40
  41 static int unix_close(MigrationState *s)
  42 {
  43     DPRINTF("unix_close\n");
  44     if (s->fd != -1) {
  45         close(s->fd);
  46         s->fd = -1;
  47     }
  48     return 0;
  49 }
  50
  51 static void unix_wait_for_connect(void *opaque)
  52 {
  53     MigrationState *s = opaque;
  54     int val, ret;
  55     socklen_t valsize = sizeof(val);
  56
  57     DPRINTF("connect completed\n");
  58     do {
  59         ret = getsockopt(s->fd, SOL_SOCKET, SO_ERROR, (void *) &val, &valsize);
  60     } while (ret == -1 && (s->get_error(s)) == EINTR);
  61
  62     if (ret < 0) {
  63         migrate_fd_error(s);
  64         return;
  65     }
  66
  67     qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
  68
  69     if (val == 0)
  70         migrate_fd_connect(s);
  71     else {
  72         DPRINTF("error connecting %d\n", val);
  73         migrate_fd_error(s);
  74     }
  75 }
  76
  77 MigrationState *unix_start_outgoing_migration(Monitor *mon,
  78                                               const char *path,
  79                                               int64_t bandwidth_limit,
  80                                               int detach,
  81                                               int blk,
  82                                               int inc)
  83 {
  84     MigrationState *s;
  85     struct sockaddr_un addr;
  86     int ret;
  87
  88     addr.sun_family = AF_UNIX;
  89     snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
  90
  91     s = migrate_new(mon, bandwidth_limit, detach, blk, inc);
  92
  93     s->get_error = unix_errno;
  94     s->write = unix_write;
  95     s->close = unix_close;
  96
  97     s->fd = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
  98     if (s->fd < 0) {
  99         DPRINTF("Unable to open socket");
 100         goto err_after_alloc;
 101     }
 102
 103     socket_set_nonblock(s->fd);
 104
 105     do {
 106         ret = connect(s->fd, (struct sockaddr *)&addr, sizeof(addr));
 107         if (ret == -1)
 108             ret = -(s->get_error(s));
 109
 110         if (ret == -EINPROGRESS || ret == -EWOULDBLOCK)
 111             qemu_set_fd_handler2(s->fd, NULL, NULL, unix_wait_for_connect, s);
 112     } while (ret == -EINTR);
 113
 114     if (ret < 0 && ret != -EINPROGRESS && ret != -EWOULDBLOCK) {
 115         DPRINTF("connect failed\n");
 116         goto err_after_open;
 117     }
 118
 119     if (ret >= 0)
 120         migrate_fd_connect(s);
 121
 122     return s;
 123
 124 err_after_open:
 125     close(s->fd);
 126
 127 err_after_alloc:
 128     g_free(s);
 129     return NULL;
 130 }
 131
 132 static void unix_accept_incoming_migration(void *opaque)
 133 {
 134     struct sockaddr_un addr;
 135     socklen_t addrlen = sizeof(addr);
 136     int s = (intptr_t)opaque;
 137     QEMUFile *f;
 138     int c;
 139
 140     do {
 141         c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
 142     } while (c == -1 && socket_error() == EINTR);
 143
 144     DPRINTF("accepted migration\n");
 145
 146     if (c == -1) {
 147         fprintf(stderr, "could not accept migration connection\n");
 148         return;
 149     }
 150
 151     f = qemu_fopen_socket(c);
 152     if (f == NULL) {
 153         fprintf(stderr, "could not qemu_fopen socket\n");
 154         goto out;
 155     }
 156
 157     process_incoming_migration(f);
 158     qemu_fclose(f);
 159 out:
 160     qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
 161     close(s);
 162     close(c);
 163 }
 164
 165 int unix_start_incoming_migration(const char *path)
 166 {
 167     struct sockaddr_un un;
 168     int sock;
 169
 170     DPRINTF("Attempting to start an incoming migration\n");
 171
 172     sock = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
 173     if (sock < 0) {
 174         fprintf(stderr, "Could not open unix socket: %s\n", strerror(errno));
 175         return -EINVAL;
 176     }
 177
 178     memset(&un, 0, sizeof(un));
 179     un.sun_family = AF_UNIX;
 180     snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);
 181
 182     unlink(un.sun_path);
 183     if (bind(sock, (struct sockaddr*) &un, sizeof(un)) < 0) {
 184         fprintf(stderr, "bind(unix:%s): %s\n", un.sun_path, strerror(errno));
 185         goto err;
 186     }
 187     if (listen(sock, 1) < 0) {
 188         fprintf(stderr, "listen(unix:%s): %s\n", un.sun_path, strerror(errno));
 189         goto err;
 190     }
 191
 192     qemu_set_fd_handler2(sock, NULL, unix_accept_incoming_migration, NULL,
 193                          (void *)(intptr_t)sock);
 194
 195     return 0;
 196
 197 err:
 198     close(sock);
 199
 200     return -EINVAL;
 201 }