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/sockets.h"
  18 #include "migration/migration.h"
  19 #include "buffered_file.h"
  20 #include "block/block.h"
  21
  22 //#define DEBUG_MIGRATION_UNIX
  23
  24 #ifdef DEBUG_MIGRATION_UNIX
  25 #define DPRINTF(fmt, ...) \
  26     do { printf("migration-unix: " fmt, ## __VA_ARGS__); } while (0)
  27 #else
  28 #define DPRINTF(fmt, ...) \
  29     do { } while (0)
  30 #endif
  31
  32 static int unix_errno(MigrationState *s)
  33 {
  34     return errno;
  35 }
  36
  37 static int unix_write(MigrationState *s, const void * buf, size_t size)
  38 {
  39     return write(s->fd, buf, size);
  40 }
  41
  42 static int unix_close(MigrationState *s)
  43 {
  44     int r = 0;
  45     DPRINTF("unix_close\n");
  46     if (close(s->fd) < 0) {
  47         r = -errno;
  48     }
  49     return r;
  50 }
  51
  52 static void unix_wait_for_connect(int fd, void *opaque)
  53 {
  54     MigrationState *s = opaque;
  55
  56     if (fd < 0) {
  57         DPRINTF("migrate connect error\n");
  58         s->fd = -1;
  59         migrate_fd_error(s);
  60     } else {
  61         DPRINTF("migrate connect success\n");
  62         s->fd = fd;
  63         migrate_fd_connect(s);
  64     }
  65 }
  66
  67 void unix_start_outgoing_migration(MigrationState *s, const char *path, Error **errp)
  68 {
  69     s->get_error = unix_errno;
  70     s->write = unix_write;
  71     s->close = unix_close;
  72
  73     s->fd = unix_nonblocking_connect(path, unix_wait_for_connect, s, errp);
  74 }
  75
  76 static void unix_accept_incoming_migration(void *opaque)
  77 {
  78     struct sockaddr_un addr;
  79     socklen_t addrlen = sizeof(addr);
  80     int s = (intptr_t)opaque;
  81     QEMUFile *f;
  82     int c;
  83
  84     do {
  85         c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
  86     } while (c == -1 && errno == EINTR);
  87     qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
  88     close(s);
  89
  90     DPRINTF("accepted migration\n");
  91
  92     if (c == -1) {
  93         fprintf(stderr, "could not accept migration connection\n");
  94         goto out;
  95     }
  96
  97     f = qemu_fopen_socket(c);
  98     if (f == NULL) {
  99         fprintf(stderr, "could not qemu_fopen socket\n");
 100         goto out;
 101     }
 102
 103     process_incoming_migration(f);
 104     return;
 105
 106 out:
 107     close(c);
 108 }
 109
 110 void unix_start_incoming_migration(const char *path, Error **errp)
 111 {
 112     int s;
 113
 114     s = unix_listen(path, NULL, 0, errp);
 115     if (s < 0) {
 116         return;
 117     }
 118
 119     qemu_set_fd_handler2(s, NULL, unix_accept_incoming_migration, NULL,
 120                          (void *)(intptr_t)s);
 121 }