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