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 (close(s->fd) < 0) {
  48         r = -errno;
  49     }
  50     return r;
  51 }
  52
  53 static void unix_wait_for_connect(int fd, void *opaque)
  54 {
  55     MigrationState *s = opaque;
  56
  57     if (fd < 0) {
  58         DPRINTF("migrate connect error\n");
  59         s->fd = -1;
  60         migrate_fd_error(s);
  61     } else {
  62         DPRINTF("migrate connect success\n");
  63         s->fd = fd;
  64         migrate_fd_connect(s);
  65     }
  66 }
  67
  68 void unix_start_outgoing_migration(MigrationState *s, const char *path, Error **errp)
  69 {
  70     s->get_error = unix_errno;
  71     s->write = unix_write;
  72     s->close = unix_close;
  73
  74     s->fd = unix_nonblocking_connect(path, unix_wait_for_connect, s, errp);
  75 }
  76
  77 static void unix_accept_incoming_migration(void *opaque)
  78 {
  79     struct sockaddr_un addr;
  80     socklen_t addrlen = sizeof(addr);
  81     int s = (intptr_t)opaque;
  82     QEMUFile *f;
  83     int c;
  84
  85     do {
  86         c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
  87     } while (c == -1 && errno == EINTR);
  88     qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
  89     close(s);
  90
  91     DPRINTF("accepted migration\n");
  92
  93     if (c == -1) {
  94         fprintf(stderr, "could not accept migration connection\n");
  95         goto out;
  96     }
  97
  98     f = qemu_fopen_socket(c);
  99     if (f == NULL) {
 100         fprintf(stderr, "could not qemu_fopen socket\n");
 101         goto out;
 102     }
 103
 104     process_incoming_migration(f);
 105     return;
 106
 107 out:
 108     close(c);
 109 }
 110
 111 void unix_start_incoming_migration(const char *path, Error **errp)
 112 {
 113     int s;
 114
 115     s = unix_listen(path, NULL, 0, errp);
 116     if (s < 0) {
 117         return;
 118     }
 119
 120     qemu_set_fd_handler2(s, NULL, unix_accept_incoming_migration, NULL,
 121                          (void *)(intptr_t)s);
 122 }