migration-fd.c

   1 /*
   2  * QEMU live migration via generic fd
   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 "monitor.h"
  18 #include "qemu-char.h"
  19 #include "buffered_file.h"
  20 #include "block.h"
  21 #include "qemu_socket.h"
  22
  23 //#define DEBUG_MIGRATION_FD
  24
  25 #ifdef DEBUG_MIGRATION_FD
  26 #define DPRINTF(fmt, ...) \
  27     do { printf("migration-fd: " fmt, ## __VA_ARGS__); } while (0)
  28 #else
  29 #define DPRINTF(fmt, ...) \
  30     do { } while (0)
  31 #endif
  32
  33 static int fd_errno(MigrationState *s)
  34 {
  35     return errno;
  36 }
  37
  38 static int fd_write(MigrationState *s, const void * buf, size_t size)
  39 {
  40     return write(s->fd, buf, size);
  41 }
  42
  43 static int fd_close(MigrationState *s)
  44 {
  45     struct stat st;
  46     int ret;
  47
  48     DPRINTF("fd_close\n");
  49     if (s->fd != -1) {
  50         ret = fstat(s->fd, &st);
  51         if (ret == 0 && S_ISREG(st.st_mode)) {
  52             /*
  53              * If the file handle is a regular file make sure the
  54              * data is flushed to disk before signaling success.
  55              */
  56             ret = fsync(s->fd);
  57             if (ret != 0) {
  58                 ret = -errno;
  59                 perror("migration-fd: fsync");
  60                 return ret;
  61             }
  62         }
  63         ret = close(s->fd);
  64         s->fd = -1;
  65         if (ret != 0) {
  66             ret = -errno;
  67             perror("migration-fd: close");
  68             return ret;
  69         }
  70     }
  71     return 0;
  72 }
  73
  74 int fd_start_outgoing_migration(MigrationState *s, const char *fdname)
  75 {
  76     s->fd = monitor_get_fd(s->mon, fdname);
  77     if (s->fd == -1) {
  78         DPRINTF("fd_migration: invalid file descriptor identifier\n");
  79         goto err_after_get_fd;
  80     }
  81
  82     if (fcntl(s->fd, F_SETFL, O_NONBLOCK) == -1) {
  83         DPRINTF("Unable to set nonblocking mode on file descriptor\n");
  84         goto err_after_open;
  85     }
  86
  87     s->get_error = fd_errno;
  88     s->write = fd_write;
  89     s->close = fd_close;
  90
  91     migrate_fd_connect(s);
  92     return 0;
  93
  94 err_after_open:
  95     close(s->fd);
  96 err_after_get_fd:
  97     return -1;
  98 }
  99
 100 static void fd_accept_incoming_migration(void *opaque)
 101 {
 102     QEMUFile *f = opaque;
 103
 104     process_incoming_migration(f);
 105     qemu_set_fd_handler2(qemu_stdio_fd(f), NULL, NULL, NULL, NULL);
 106     qemu_fclose(f);
 107 }
 108
 109 int fd_start_incoming_migration(const char *infd)
 110 {
 111     int fd;
 112     QEMUFile *f;
 113
 114     DPRINTF("Attempting to start an incoming migration via fd\n");
 115
 116     fd = strtol(infd, NULL, 0);
 117     f = qemu_fdopen(fd, "rb");
 118     if(f == NULL) {
 119         DPRINTF("Unable to apply qemu wrapper to file descriptor\n");
 120         return -errno;
 121     }
 122
 123     qemu_set_fd_handler2(fd, NULL, fd_accept_incoming_migration, NULL, f);
 124
 125     return 0;
 126 }