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     int r = 0;
  44     DPRINTF("unix_close\n");
  45     if (s->fd != -1) {
  46         if (close(s->fd) < 0) {
  47             r = -errno;
  48         }
  49         s->fd = -1;
  50     }
  51     return r;
  52 }
  53
  54 static void unix_wait_for_connect(void *opaque)
  55 {
  56     MigrationState *s = opaque;
  57     int val, ret;
  58     socklen_t valsize = sizeof(val);
  59
  60     DPRINTF("connect completed\n");
  61     do {
  62         ret = getsockopt(s->fd, SOL_SOCKET, SO_ERROR, (void *) &val, &valsize);
  63     } while (ret == -1 && errno == EINTR);
  64
  65     if (ret < 0) {
  66         migrate_fd_error(s);
  67         return;
  68     }
  69
  70     qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
  71
  72     if (val == 0)
  73         migrate_fd_connect(s);
  74     else {
  75         DPRINTF("error connecting %d\n", val);
  76         migrate_fd_error(s);
  77     }
  78 }
  79
  80 int unix_start_outgoing_migration(MigrationState *s, const char *path)
  81 {
  82     struct sockaddr_un addr;
  83     int ret;
  84
  85     addr.sun_family = AF_UNIX;
  86     snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
  87     s->get_error = unix_errno;
  88     s->write = unix_write;
  89     s->close = unix_close;
  90
  91     s->fd = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
  92     if (s->fd == -1) {
  93         DPRINTF("Unable to open socket");
  94         return -errno;
  95     }
  96
  97     socket_set_nonblock(s->fd);
  98
  99     do {
 100         ret = connect(s->fd, (struct sockaddr *)&addr, sizeof(addr));
 101         if (ret == -1) {
 102             ret = -errno;
 103         }
 104         if (ret == -EINPROGRESS || ret == -EWOULDBLOCK) {
 105             qemu_set_fd_handler2(s->fd, NULL, NULL, unix_wait_for_connect, s);
 106             return 0;
 107         }
 108     } while (ret == -EINTR);
 109
 110     if (ret < 0) {
 111         DPRINTF("connect failed\n");
 112         migrate_fd_error(s);
 113         return ret;
 114     }
 115     migrate_fd_connect(s);
 116     return 0;
 117 }
 118
 119 static void unix_accept_incoming_migration(void *opaque)
 120 {
 121     struct sockaddr_un addr;
 122     socklen_t addrlen = sizeof(addr);
 123     int s = (intptr_t)opaque;
 124     QEMUFile *f;
 125     int c;
 126
 127     do {
 128         c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
 129     } while (c == -1 && errno == EINTR);
 130
 131     DPRINTF("accepted migration\n");
 132
 133     if (c == -1) {
 134         fprintf(stderr, "could not accept migration connection\n");
 135         goto out2;
 136     }
 137
 138     f = qemu_fopen_socket(c);
 139     if (f == NULL) {
 140         fprintf(stderr, "could not qemu_fopen socket\n");
 141         goto out;
 142     }
 143
 144     process_incoming_migration(f);
 145     qemu_fclose(f);
 146 out:
 147     close(c);
 148 out2:
 149     qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
 150     close(s);
 151 }
 152
 153 int unix_start_incoming_migration(const char *path)
 154 {
 155     struct sockaddr_un addr;
 156     int s;
 157     int ret;
 158
 159     DPRINTF("Attempting to start an incoming migration\n");
 160
 161     s = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
 162     if (s == -1) {
 163         fprintf(stderr, "Could not open unix socket: %s\n", strerror(errno));
 164         return -errno;
 165     }
 166
 167     memset(&addr, 0, sizeof(addr));
 168     addr.sun_family = AF_UNIX;
 169     snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
 170
 171     unlink(addr.sun_path);
 172     if (bind(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
 173         ret = -errno;
 174         fprintf(stderr, "bind(unix:%s): %s\n", addr.sun_path, strerror(errno));
 175         goto err;
 176     }
 177     if (listen(s, 1) == -1) {
 178         fprintf(stderr, "listen(unix:%s): %s\n", addr.sun_path,
 179                 strerror(errno));
 180         ret = -errno;
 181         goto err;
 182     }
 183
 184     qemu_set_fd_handler2(s, NULL, unix_accept_incoming_migration, NULL,
 185                          (void *)(intptr_t)s);
 186
 187     return 0;
 188
 189 err:
 190     close(s);
 191     return ret;
 192 }