migration/fd.c

/*
 * QEMU live migration via generic fd
 *
 * Copyright Red Hat, Inc. 2009-2016
 *
 * Authors:
 *  Chris Lalancette <clalance@redhat.com>
 *  Daniel P. Berrange <berrange@redhat.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 *
 * Contributions after 2012-01-13 are licensed under the terms of the
 * GNU GPL, version 2 or (at your option) any later version.
 */

#include "qemu/osdep.h"
#include "channel.h"
#include "fd.h"
#include "file.h"
#include "migration.h"
#include "monitor/monitor.h"
#include "qemu/error-report.h"
#include "qemu/sockets.h"
#include "io/channel-util.h"
#include "trace.h"
#include "qapi/error.h"

static bool fd_is_pipe(int fd)
{
    struct stat statbuf;

    if (fstat(fd, &statbuf) == -1) {
        return false;
    }

    return S_ISFIFO(statbuf.st_mode);
}

static bool migration_fd_valid(int fd, Error **errp)
{
    if (migrate_local() && migrate_mode() != MIG_MODE_CPR_EXEC) {
        struct sockaddr_storage ss;
        socklen_t sslen = sizeof(ss);

        if (getsockname(fd, (struct sockaddr *)&ss, &sslen) < 0 ||
            ss.ss_family != AF_UNIX) {
            error_setg(errp,
                       "local migration requires a UNIX domain socket channel");
            return false;
        }

        return true;
    }

    if (fd_is_socket(fd) || fd_is_pipe(fd)) {
        return true;
    }

    error_setg(errp, "fd: migration to a file is not supported."
               " Use file: instead.");
    return false;
}

QIOChannel *fd_connect_outgoing(MigrationState *s, const char *fdname,
                                Error **errp)
{
    QIOChannel *ioc = NULL;
    int fd = monitor_get_fd(monitor_cur(), fdname, errp);
    if (fd == -1) {
        goto out;
    }

    if (!migration_fd_valid(fd, errp)) {
        close(fd);
        goto out;
    }

    trace_migration_fd_outgoing(fd);
    ioc = qio_channel_new_fd(fd, errp);
    if (!ioc) {
        close(fd);
        goto out;
    }

    qio_channel_set_name(ioc, "migration-fd-outgoing");
out:
    return ioc;
}

static gboolean fd_accept_incoming_migration(QIOChannel *ioc,
                                             GIOCondition condition,
                                             gpointer opaque)
{
    migration_channel_process_incoming(ioc);
    object_unref(OBJECT(ioc));
    return G_SOURCE_REMOVE;
}

void fd_connect_incoming(const char *fdname, Error **errp)
{
    QIOChannel *ioc;
    int fd = monitor_fd_param(monitor_cur(), fdname, errp);
    if (fd == -1) {
        return;
    }

    if (!migration_fd_valid(fd, errp)) {
        close(fd);
        return;
    }

    trace_migration_fd_incoming(fd);

    ioc = qio_channel_new_fd(fd, errp);
    if (!ioc) {
        close(fd);
        return;
    }

    qio_channel_set_name(ioc, "migration-fd-incoming");
    qio_channel_add_watch_full(ioc, G_IO_IN,
                               fd_accept_incoming_migration,
                               NULL, NULL,
                               g_main_context_get_thread_default());
}