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 && errno == 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 int unix_start_outgoing_migration(MigrationState *s, const char *path)
  78 {
  79     struct sockaddr_un addr;
  80     int ret;
  81
  82     addr.sun_family = AF_UNIX;
  83     snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
  84     s->get_error = unix_errno;
  85     s->write = unix_write;
  86     s->close = unix_close;
  87
  88     s->fd = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
  89     if (s->fd == -1) {
  90         DPRINTF("Unable to open socket");
  91         return -errno;
  92     }
  93
  94     socket_set_nonblock(s->fd);
  95
  96     do {
  97         ret = connect(s->fd, (struct sockaddr *)&addr, sizeof(addr));
  98         if (ret == -1) {
  99             ret = -errno;
 100         }
 101         if (ret == -EINPROGRESS || ret == -EWOULDBLOCK) {
 102             qemu_set_fd_handler2(s->fd, NULL, NULL, unix_wait_for_connect, s);
 103             return 0;
 104         }
 105     } while (ret == -EINTR);
 106
 107     if (ret < 0) {
 108         DPRINTF("connect failed\n");
 109         migrate_fd_error(s);
 110         return ret;
 111     }
 112     migrate_fd_connect(s);
 113     return 0;
 114 }
 115
 116 static void unix_accept_incoming_migration(void *opaque)
 117 {
 118     struct sockaddr_un addr;
 119     socklen_t addrlen = sizeof(addr);
 120     int s = (intptr_t)opaque;
 121     QEMUFile *f;
 122     int c;
 123
 124     do {
 125         c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
 126     } while (c == -1 && errno == EINTR);
 127
 128     DPRINTF("accepted migration\n");
 129
 130     if (c == -1) {
 131         fprintf(stderr, "could not accept migration connection\n");
 132         goto out2;
 133     }
 134
 135     f = qemu_fopen_socket(c);
 136     if (f == NULL) {
 137         fprintf(stderr, "could not qemu_fopen socket\n");
 138         goto out;
 139     }
 140
 141     process_incoming_migration(f);
 142     qemu_fclose(f);
 143 out:
 144     close(c);
 145 out2:
 146     qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
 147     close(s);
 148 }
 149
 150 int unix_start_incoming_migration(const char *path)
 151 {
 152     struct sockaddr_un addr;
 153     int s;
 154     int ret;
 155
 156     DPRINTF("Attempting to start an incoming migration\n");
 157
 158     s = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
 159     if (s == -1) {
 160         fprintf(stderr, "Could not open unix socket: %s\n", strerror(errno));
 161         return -errno;
 162     }
 163
 164     memset(&addr, 0, sizeof(addr));
 165     addr.sun_family = AF_UNIX;
 166     snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
 167
 168     unlink(addr.sun_path);
 169     if (bind(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
 170         ret = -errno;
 171         fprintf(stderr, "bind(unix:%s): %s\n", addr.sun_path, strerror(errno));
 172         goto err;
 173     }
 174     if (listen(s, 1) == -1) {
 175         fprintf(stderr, "listen(unix:%s): %s\n", addr.sun_path,
 176                 strerror(errno));
 177         ret = -errno;
 178         goto err;
 179     }
 180
 181     qemu_set_fd_handler2(s, NULL, unix_accept_incoming_migration, NULL,
 182                          (void *)(intptr_t)s);
 183
 184     return 0;
 185
 186 err:
 187     close(s);
 188     return ret;
 189 }