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 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 < 0) {
  90         DPRINTF("Unable to open socket");
  91         goto err_after_socket;
  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 = -(s->get_error(s));
 100
 101         if (ret == -EINPROGRESS || ret == -EWOULDBLOCK)
 102             qemu_set_fd_handler2(s->fd, NULL, NULL, unix_wait_for_connect, s);
 103     } while (ret == -EINTR);
 104
 105     if (ret < 0 && ret != -EINPROGRESS && ret != -EWOULDBLOCK) {
 106         DPRINTF("connect failed\n");
 107         goto err_after_open;
 108     }
 109
 110     if (ret >= 0)
 111         migrate_fd_connect(s);
 112
 113     return 0;
 114
 115 err_after_open:
 116     close(s->fd);
 117
 118 err_after_socket:
 119     return -1;
 120 }
 121
 122 static void unix_accept_incoming_migration(void *opaque)
 123 {
 124     struct sockaddr_un addr;
 125     socklen_t addrlen = sizeof(addr);
 126     int s = (intptr_t)opaque;
 127     QEMUFile *f;
 128     int c;
 129
 130     do {
 131         c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
 132     } while (c == -1 && socket_error() == EINTR);
 133
 134     DPRINTF("accepted migration\n");
 135
 136     if (c == -1) {
 137         fprintf(stderr, "could not accept migration connection\n");
 138         return;
 139     }
 140
 141     f = qemu_fopen_socket(c);
 142     if (f == NULL) {
 143         fprintf(stderr, "could not qemu_fopen socket\n");
 144         goto out;
 145     }
 146
 147     process_incoming_migration(f);
 148     qemu_fclose(f);
 149 out:
 150     qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
 151     close(s);
 152     close(c);
 153 }
 154
 155 int unix_start_incoming_migration(const char *path)
 156 {
 157     struct sockaddr_un un;
 158     int sock;
 159
 160     DPRINTF("Attempting to start an incoming migration\n");
 161
 162     sock = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
 163     if (sock < 0) {
 164         fprintf(stderr, "Could not open unix socket: %s\n", strerror(errno));
 165         return -EINVAL;
 166     }
 167
 168     memset(&un, 0, sizeof(un));
 169     un.sun_family = AF_UNIX;
 170     snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);
 171
 172     unlink(un.sun_path);
 173     if (bind(sock, (struct sockaddr*) &un, sizeof(un)) < 0) {
 174         fprintf(stderr, "bind(unix:%s): %s\n", un.sun_path, strerror(errno));
 175         goto err;
 176     }
 177     if (listen(sock, 1) < 0) {
 178         fprintf(stderr, "listen(unix:%s): %s\n", un.sun_path, strerror(errno));
 179         goto err;
 180     }
 181
 182     qemu_set_fd_handler2(sock, NULL, unix_accept_incoming_migration, NULL,
 183                          (void *)(intptr_t)sock);
 184
 185     return 0;
 186
 187 err:
 188     close(sock);
 189
 190     return -EINVAL;
 191 }