xm_internal.c

/*
 * xm_internal.h: helper routines for dealing with inactive domains
 *
 * Copyright (C) 2006-2007, 2009-2011 Red Hat, Inc.
 * Copyright (C) 2006 Daniel P. Berrange
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 *
 * Author: Daniel P. Berrange <berrange@redhat.com>
 *
 */

#include <config.h>

#include <dirent.h>
#include <time.h>
#include <sys/stat.h>
#include <limits.h>
#include <string.h>
#include <errno.h>

#include <unistd.h>
#include <stdint.h>
#include <xen/dom0_ops.h>

#include "virterror_internal.h"
#include "datatypes.h"
#include "xm_internal.h"
#include "xen_driver.h"
#include "xend_internal.h"
#include "xen_sxpr.h"
#include "xen_xm.h"
#include "hash.h"
#include "buf.h"
#include "uuid.h"
#include "util.h"
#include "memory.h"
#include "logging.h"
#include "count-one-bits.h"

#define VIR_FROM_THIS VIR_FROM_XENXM

#ifdef WITH_RHEL5_API
# define XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU 0
# define XEND_CONFIG_MIN_VERS_PVFB_NEWCONF 2
#else
# define XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU 3
# define XEND_CONFIG_MIN_VERS_PVFB_NEWCONF 3
#endif

/* The true Xen limit varies but so far is always way
   less than 1024, which is the Linux kernel limit according
   to sched.h, so we'll match that for now */
#define XEN_MAX_PHYSICAL_CPU 1024

char * xenXMAutoAssignMac(void);
static int xenXMDomainAttachDeviceFlags(virDomainPtr domain, const char *xml,
                                        unsigned int flags);
static int xenXMDomainDetachDeviceFlags(virDomainPtr domain, const char *xml,
                                        unsigned int flags);

#define XM_REFRESH_INTERVAL 10

#define XM_CONFIG_DIR "/etc/xen"
#define XM_EXAMPLE_PREFIX "xmexample"
#define XEND_CONFIG_FILE "xend-config.sxp"
#define XEND_PCI_CONFIG_PREFIX "xend-pci-"
#define QEMU_IF_SCRIPT "qemu-ifup"
#define XM_XML_ERROR "Invalid xml"

struct xenUnifiedDriver xenXMDriver = {
    xenXMOpen, /* open */
    xenXMClose, /* close */
    NULL, /* version */
    NULL, /* hostname */
    NULL, /* nodeGetInfo */
    NULL, /* getCapabilities */
    NULL, /* listDomains */
    NULL, /* numOfDomains */
    NULL, /* domainCreateXML */
    NULL, /* domainSuspend */
    NULL, /* domainResume */
    NULL, /* domainShutdown */
    NULL, /* domainReboot */
    NULL, /* domainDestroy */
    NULL, /* domainGetOSType */
    xenXMDomainGetMaxMemory, /* domainGetMaxMemory */
    xenXMDomainSetMaxMemory, /* domainSetMaxMemory */
    xenXMDomainSetMemory, /* domainMaxMemory */
    xenXMDomainGetInfo, /* domainGetInfo */
    NULL, /* domainSave */
    NULL, /* domainRestore */
    NULL, /* domainCoreDump */
    xenXMDomainPinVcpu, /* domainPinVcpu */
    NULL, /* domainGetVcpus */
    xenXMListDefinedDomains, /* listDefinedDomains */
    xenXMNumOfDefinedDomains, /* numOfDefinedDomains */
    xenXMDomainCreate, /* domainCreate */
    xenXMDomainDefineXML, /* domainDefineXML */
    xenXMDomainUndefine, /* domainUndefine */
    xenXMDomainAttachDeviceFlags, /* domainAttachDeviceFlags */
    xenXMDomainDetachDeviceFlags, /* domainDetachDeviceFlags */
    NULL, /* domainUpdateDeviceFlags */
    NULL, /* domainGetAutostart */
    NULL, /* domainSetAutostart */
    NULL, /* domainGetSchedulerType */
    NULL, /* domainGetSchedulerParameters */
    NULL, /* domainSetSchedulerParameters */
};

#define xenXMError(code, ...)                                              \
        virReportErrorHelper(VIR_FROM_XENXM, code, __FILE__,               \
                             __FUNCTION__, __LINE__, __VA_ARGS__)

#ifndef WITH_XEN_INOTIFY
static int xenInotifyActive(virConnectPtr conn ATTRIBUTE_UNUSED)
{
   return 0;
}
#else
static int xenInotifyActive(virConnectPtr conn)
{
   xenUnifiedPrivatePtr priv = (xenUnifiedPrivatePtr) conn->privateData;
   return priv->inotifyWatch > 0;
}
#endif


/* Release memory associated with a cached config object */
static void xenXMConfigFree(void *payload, const void *key ATTRIBUTE_UNUSED) {
    xenXMConfCachePtr entry = (xenXMConfCachePtr)payload;
    virDomainDefFree(entry->def);
    VIR_FREE(entry);
}

struct xenXMConfigReaperData {
    xenUnifiedPrivatePtr priv;
    time_t now;
};

/* Remove any configs which were not refreshed recently */
static int xenXMConfigReaper(const void *payload, const void *key ATTRIBUTE_UNUSED, const void *data) {
    const struct xenXMConfigReaperData *args = data;
    xenXMConfCachePtr entry = (xenXMConfCachePtr)payload;

    /* We're going to purge this config file, so check if it
       is currently mapped as owner of a named domain. */
    if (entry->refreshedAt != args->now) {
        const char *olddomname = entry->def->name;
        char *nameowner = (char *)virHashLookup(args->priv->nameConfigMap, olddomname);
        if (nameowner && STREQ(nameowner, key)) {
            virHashRemoveEntry(args->priv->nameConfigMap, olddomname);
        }
        return (1);
    }
    return (0);
}


static virDomainDefPtr
xenXMConfigReadFile(virConnectPtr conn, const char *filename) {
    virConfPtr conf;
    virDomainDefPtr def;
    xenUnifiedPrivatePtr priv = conn->privateData;

    if (!(conf = virConfReadFile(filename, 0)))
        return NULL;

    def = xenParseXM(conf, priv->xendConfigVersion, priv->caps);
    virConfFree(conf);

    return def;
}

static int
xenXMConfigSaveFile(virConnectPtr conn, const char *filename, virDomainDefPtr def) {
    virConfPtr conf;
    xenUnifiedPrivatePtr priv = conn->privateData;
    int ret;

    if (!(conf = xenFormatXM(conn, def, priv->xendConfigVersion)))
        return -1;

    ret = virConfWriteFile(filename, conf);
    virConfFree(conf);
    return ret;
}


/*
 * Caller must hold the lock on 'conn->privateData' before
 * calling this funtion
 */
int
xenXMConfigCacheRemoveFile(virConnectPtr conn,
                           const char *filename)
{
    xenUnifiedPrivatePtr priv = conn->privateData;
    xenXMConfCachePtr entry;

    entry = virHashLookup(priv->configCache, filename);
    if (!entry) {
        VIR_DEBUG("No config entry for %s", filename);
        return 0;
    }

    virHashRemoveEntry(priv->nameConfigMap, entry->def->name);
    virHashRemoveEntry(priv->configCache, filename);
    VIR_DEBUG("Removed %s %s", entry->def->name, filename);
    return 0;
}


/*
 * Caller must hold the lock on 'conn->privateData' before
 * calling this funtion
 */
int
xenXMConfigCacheAddFile(virConnectPtr conn, const char *filename)
{
    xenUnifiedPrivatePtr priv = conn->privateData;
    xenXMConfCachePtr entry;
    struct stat st;
    int newborn = 0;
    time_t now = time(NULL);

    VIR_DEBUG("Adding file %s", filename);

    /* Get modified time */
    if ((stat(filename, &st) < 0)) {
        virReportSystemError(errno,
                             _("cannot stat: %s"),
                             filename);
        return -1;
    }

    /* Ignore zero length files, because inotify fires before
       any content has actually been created */
    if (st.st_size == 0) {
        VIR_DEBUG("Ignoring zero length file %s", filename);
        return -1;
    }

    /* If we already have a matching entry and it is not
    modified, then carry on to next one*/
    if ((entry = virHashLookup(priv->configCache, filename))) {
        char *nameowner;

        if (entry->refreshedAt >= st.st_mtime) {
            entry->refreshedAt = now;
            /* return success if up-to-date */
            return 0;
        }

        /* If we currently own the name, then release it and
            re-acquire it later - just in case it was renamed */
        nameowner = (char *)virHashLookup(priv->nameConfigMap, entry->def->name);
        if (nameowner && STREQ(nameowner, filename)) {
            virHashRemoveEntry(priv->nameConfigMap, entry->def->name);
        }

        /* Clear existing config entry which needs refresh */
        virDomainDefFree(entry->def);
        entry->def = NULL;
    } else { /* Completely new entry */
        newborn = 1;
        if (VIR_ALLOC(entry) < 0) {
            virReportOOMError();
            return -1;
        }
        memcpy(entry->filename, filename, PATH_MAX);
    }
    entry->refreshedAt = now;

    if (!(entry->def = xenXMConfigReadFile(conn, entry->filename))) {
        VIR_DEBUG("Failed to read %s", entry->filename);
        if (!newborn)
            virHashSteal(priv->configCache, filename);
        VIR_FREE(entry);
        return -1;
    }

    /* If its a completely new entry, it must be stuck into
        the cache (refresh'd entries are already registered) */
    if (newborn) {
        if (virHashAddEntry(priv->configCache, entry->filename, entry) < 0) {
            virDomainDefFree(entry->def);
            VIR_FREE(entry);
            xenXMError(VIR_ERR_INTERNAL_ERROR,
                        "%s", _("xenXMConfigCacheRefresh: virHashAddEntry"));
            return -1;
        }
    }

    /* See if we need to map this config file in as the primary owner
        * of the domain in question
        */
    if (!virHashLookup(priv->nameConfigMap, entry->def->name)) {
        if (virHashAddEntry(priv->nameConfigMap, entry->def->name, entry->filename) < 0) {
            virHashSteal(priv->configCache, filename);
            virDomainDefFree(entry->def);
            VIR_FREE(entry);
        }
    }
    VIR_DEBUG("Added config %s %s", entry->def->name, filename);

    return 0;
}

/* This method is called by various methods to scan /etc/xen
 * (or whatever directory was set by  LIBVIRT_XM_CONFIG_DIR
 * environment variable) and process any domain configs. It
 * has rate-limited so never rescans more frequently than
 * once every X seconds
 *
 * Caller must hold the lock on 'conn->privateData' before
 * calling this funtion
 */
int xenXMConfigCacheRefresh (virConnectPtr conn) {
    xenUnifiedPrivatePtr priv = conn->privateData;
    DIR *dh;
    struct dirent *ent;
    time_t now = time(NULL);
    int ret = -1;
    struct xenXMConfigReaperData args;

    if (now == ((time_t)-1)) {
        virReportSystemError(errno,
                             "%s", _("cannot get time of day"));
        return (-1);
    }

    /* Rate limit re-scans */
    if ((now - priv->lastRefresh) < XM_REFRESH_INTERVAL)
        return (0);

    priv->lastRefresh = now;

    /* Process the files in the config dir */
    if (!(dh = opendir(priv->configDir))) {
        virReportSystemError(errno,
                             _("cannot read directory %s"),
                             priv->configDir);
        return (-1);
    }

    while ((ent = readdir(dh))) {
        struct stat st;
        char *path;

        /*
         * Skip a bunch of crufty files that clearly aren't config files
         */

        /* Like 'dot' files... */
        if (STRPREFIX(ent->d_name, "."))
            continue;
        /* ...and the XenD server config file */
        if (STRPREFIX(ent->d_name, XEND_CONFIG_FILE))
            continue;
        /* ...and random PCI config cruft */
        if (STRPREFIX(ent->d_name, XEND_PCI_CONFIG_PREFIX))
            continue;
        /* ...and the example domain configs */
        if (STRPREFIX(ent->d_name, XM_EXAMPLE_PREFIX))
            continue;
        /* ...and the QEMU networking script */
        if (STRPREFIX(ent->d_name, QEMU_IF_SCRIPT))
            continue;

        /* ...and editor backups */
        if (ent->d_name[0] == '#')
            continue;
        if (ent->d_name[strlen(ent->d_name)-1] == '~')
            continue;

        /* Build the full file path */
        if (!(path = virFileBuildPath(priv->configDir, ent->d_name, NULL))) {
            closedir(dh);
            return -1;
        }

        /* Skip anything which isn't a file (takes care of scripts/ subdir */
        if ((stat(path, &st) < 0) ||
            (!S_ISREG(st.st_mode))) {
            VIR_FREE(path);
            continue;
        }

        /* If we already have a matching entry and it is not
           modified, then carry on to next one*/
        if (xenXMConfigCacheAddFile(conn, path) < 0) {
            /* Ignoring errors, since alot of stuff goes wrong in /etc/xen */
        }

        VIR_FREE(path);
    }

    /* Reap all entries which were not changed, by comparing
       their refresh timestamp - the timestamp should match
       'now' if they were refreshed. If timestamp doesn't match
       then the config is no longer on disk */
    args.now = now;
    args.priv = priv;
    virHashRemoveSet(priv->configCache, xenXMConfigReaper, &args);
    ret = 0;

    closedir(dh);

    return (ret);
}


/*
 * The XM driver keeps a cache of config files as virDomainDefPtr
 * objects in the xenUnifiedPrivatePtr. Optionally inotify lets
 * us watch for changes (see separate driver), otherwise we poll
 * every few seconds
 */
virDrvOpenStatus
xenXMOpen (virConnectPtr conn,
           virConnectAuthPtr auth ATTRIBUTE_UNUSED,
           int flags ATTRIBUTE_UNUSED)
{
    xenUnifiedPrivatePtr priv = conn->privateData;

    priv->configDir = XM_CONFIG_DIR;

    priv->configCache = virHashCreate(50, xenXMConfigFree);
    if (!priv->configCache)
        return (-1);
    priv->nameConfigMap = virHashCreate(50, NULL);
    if (!priv->nameConfigMap) {
        virHashFree(priv->configCache);
        priv->configCache = NULL;
        return (-1);
    }
    /* Force the cache to be reloaded next time that
     * xenXMConfigCacheRefresh is called.
     */
    priv->lastRefresh = 0;

    return (0);
}

/*
 * Free the cached config files associated with this
 * connection
 */
int xenXMClose(virConnectPtr conn) {
    xenUnifiedPrivatePtr priv = conn->privateData;

    virHashFree(priv->nameConfigMap);
    virHashFree(priv->configCache);

    return (0);
}

/*
 * Since these are all offline domains, we only return info about
 * VCPUs and memory.
 */
int xenXMDomainGetInfo(virDomainPtr domain, virDomainInfoPtr info) {
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;
    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return(-1);
    }

    if (domain->id != -1)
        return (-1);

    priv = domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto error;

    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto error;

    memset(info, 0, sizeof(virDomainInfo));
    info->maxMem = entry->def->mem.max_balloon;
    info->memory = entry->def->mem.cur_balloon;
    info->nrVirtCpu = entry->def->vcpus;
    info->state = VIR_DOMAIN_SHUTOFF;
    info->cpuTime = 0;

    xenUnifiedUnlock(priv);
    return (0);

error:
    xenUnifiedUnlock(priv);
    return -1;
}


/*
 * Turn a config record into a lump of XML describing the
 * domain, suitable for later feeding for virDomainCreateXML
 */
char *xenXMDomainDumpXML(virDomainPtr domain, int flags) {
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;
    char *ret = NULL;

    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return(NULL);
    }
    if (domain->id != -1)
        return (NULL);

    priv = domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto cleanup;

    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto cleanup;

    ret = virDomainDefFormat(entry->def, flags);

cleanup:
    xenUnifiedUnlock(priv);
    return ret;
}


/*
 * Update amount of memory in the config file
 */
int xenXMDomainSetMemory(virDomainPtr domain, unsigned long memory) {
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;
    int ret = -1;

    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return (-1);
    }
    if (domain->conn->flags & VIR_CONNECT_RO)
        return (-1);
    if (domain->id != -1)
        return (-1);
    if (memory < 1024 * MIN_XEN_GUEST_SIZE)
        return (-1);

    priv = domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto cleanup;

    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto cleanup;

    entry->def->mem.cur_balloon = memory;
    if (entry->def->mem.cur_balloon > entry->def->mem.max_balloon)
        entry->def->mem.cur_balloon = entry->def->mem.max_balloon;

    /* If this fails, should we try to undo our changes to the
     * in-memory representation of the config file. I say not!
     */
    if (xenXMConfigSaveFile(domain->conn, entry->filename, entry->def) < 0)
        goto cleanup;
    ret = 0;

cleanup:
    xenUnifiedUnlock(priv);
    return ret;
}

/*
 * Update maximum memory limit in config
 */
int xenXMDomainSetMaxMemory(virDomainPtr domain, unsigned long memory) {
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;
    int ret = -1;

    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return (-1);
    }
    if (domain->conn->flags & VIR_CONNECT_RO)
        return (-1);
    if (domain->id != -1)
        return (-1);

    priv = domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto cleanup;

    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto cleanup;

    entry->def->mem.max_balloon = memory;
    if (entry->def->mem.cur_balloon > entry->def->mem.max_balloon)
        entry->def->mem.cur_balloon = entry->def->mem.max_balloon;

    /* If this fails, should we try to undo our changes to the
     * in-memory representation of the config file. I say not!
     */
    if (xenXMConfigSaveFile(domain->conn, entry->filename, entry->def) < 0)
        goto cleanup;
    ret = 0;

cleanup:
    xenUnifiedUnlock(priv);
    return ret;
}

/*
 * Get max memory limit from config
 */
unsigned long xenXMDomainGetMaxMemory(virDomainPtr domain) {
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;
    unsigned long ret = 0;

    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return (0);
    }
    if (domain->id != -1)
        return (0);

    priv = domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto cleanup;

    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto cleanup;

    ret = entry->def->mem.max_balloon;

cleanup:
    xenUnifiedUnlock(priv);
    return ret;
}

/*
 * xenXMDomainSetVcpusFlags:
 * @domain: pointer to domain object
 * @nvcpus: number of vcpus
 * @flags: bitwise-ORd from virDomainVcpuFlags
 *
 * Change virtual CPUs allocation of domain according to flags.
 *
 * Returns 0 on success, -1 if an error message was issued, and -2 if
 * the unified driver should keep trying.
 */
int
xenXMDomainSetVcpusFlags(virDomainPtr domain, unsigned int vcpus,
                         unsigned int flags)
{
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;
    int ret = -1;
    int max;

    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return -1;
    }
    if (domain->conn->flags & VIR_CONNECT_RO) {
        xenXMError(VIR_ERR_OPERATION_DENIED, __FUNCTION__);
        return -1;
    }
    if (domain->id != -1)
        return -2;
    if (flags & VIR_DOMAIN_VCPU_LIVE) {
        xenXMError(VIR_ERR_OPERATION_INVALID, "%s",
                   _("domain is not running"));
        return -1;
    }

    priv = domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto cleanup;

    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto cleanup;

    /* Hypervisor maximum. */
    if ((max = xenUnifiedGetMaxVcpus(domain->conn, NULL)) < 0) {
        xenXMError(VIR_ERR_INTERNAL_ERROR, "%s",
                   _("could not determin max vcpus for the domain"));
        goto cleanup;
    }
    /* Can't specify a current larger than stored maximum; but
     * reducing maximum can silently reduce current.  */
    if (!(flags & VIR_DOMAIN_VCPU_MAXIMUM))
        max = entry->def->maxvcpus;
    if (vcpus > max) {
        xenXMError(VIR_ERR_INVALID_ARG,
                   _("requested vcpus is greater than max allowable"
                     " vcpus for the domain: %d > %d"), vcpus, max);
        goto cleanup;
    }

    if (flags & VIR_DOMAIN_VCPU_MAXIMUM) {
        entry->def->maxvcpus = vcpus;
        if (entry->def->vcpus > vcpus)
            entry->def->vcpus = vcpus;
    } else {
        entry->def->vcpus = vcpus;
    }

    /* If this fails, should we try to undo our changes to the
     * in-memory representation of the config file. I say not!
     */
    if (xenXMConfigSaveFile(domain->conn, entry->filename, entry->def) < 0)
        goto cleanup;
    ret = 0;

cleanup:
    xenUnifiedUnlock(priv);
    return ret;
}

/**
 * xenXMDomainGetVcpusFlags:
 * @domain: pointer to domain object
 * @flags: bitwise-ORd from virDomainVcpuFlags
 *
 * Extract information about virtual CPUs of domain according to flags.
 *
 * Returns the number of vcpus on success, -1 if an error message was
 * issued, and -2 if the unified driver should keep trying.
 */
int
xenXMDomainGetVcpusFlags(virDomainPtr domain, unsigned int flags)
{
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;
    int ret = -2;

    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return -1;
    }

    if (domain->id != -1)
        return -2;
    if (flags & VIR_DOMAIN_VCPU_LIVE) {
        xenXMError(VIR_ERR_OPERATION_FAILED, "%s", _("domain not active"));
        return -1;
    }

    priv = domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto cleanup;

    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto cleanup;

    ret = ((flags & VIR_DOMAIN_VCPU_MAXIMUM) ? entry->def->maxvcpus
           : entry->def->vcpus);

cleanup:
    xenUnifiedUnlock(priv);
    return ret;
}

/**
 * xenXMDomainPinVcpu:
 * @domain: pointer to domain object
 * @vcpu: virtual CPU number (reserved)
 * @cpumap: pointer to a bit map of real CPUs (in 8-bit bytes)
 * @maplen: length of cpumap in bytes
 *
 * Set the vcpu affinity in config
 *
 * Returns 0 for success; -1 (with errno) on error
 */
int xenXMDomainPinVcpu(virDomainPtr domain,
                       unsigned int vcpu ATTRIBUTE_UNUSED,
                       unsigned char *cpumap, int maplen)
{
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;
    virBuffer mapbuf = VIR_BUFFER_INITIALIZER;
    char *mapstr = NULL, *mapsave = NULL;
    int i, j, n, comma = 0;
    int ret = -1;
    char *cpuset = NULL;
    int maxcpu = XEN_MAX_PHYSICAL_CPU;

    if (domain == NULL || domain->conn == NULL || domain->name == NULL
        || cpumap == NULL || maplen < 1 || maplen > (int)sizeof(cpumap_t)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return -1;
    }
    if (domain->conn->flags & VIR_CONNECT_RO) {
        xenXMError(VIR_ERR_INVALID_ARG,
                    "%s", _("read only connection"));
        return -1;
    }
    if (domain->id != -1) {
        xenXMError(VIR_ERR_INVALID_ARG,
                    "%s", _("not inactive domain"));
        return -1;
    }

    priv = domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name))) {
        xenXMError(VIR_ERR_INTERNAL_ERROR, "%s", _("virHashLookup"));
        goto cleanup;
    }
    if (!(entry = virHashLookup(priv->configCache, filename))) {
        xenXMError(VIR_ERR_INTERNAL_ERROR,
                    "%s", _("can't retrieve config file for domain"));
        goto cleanup;
    }

    /* from bit map, build character string of mapped CPU numbers */
    for (i = 0; i < maplen; i++)
        for (j = 0; j < 8; j++)
            if ((cpumap[i] & (1 << j))) {
                n = i*8 + j;

                if (comma)
                    virBufferAddLit (&mapbuf, ",");
                comma = 1;

                virBufferAsprintf (&mapbuf, "%d", n);
            }

    if (virBufferError(&mapbuf)) {
        virBufferFreeAndReset(&mapbuf);
        virReportOOMError();
        goto cleanup;
    }

    mapstr = virBufferContentAndReset(&mapbuf);
    mapsave = mapstr;

    if (VIR_ALLOC_N(cpuset, maxcpu) < 0) {
        virReportOOMError();
        goto cleanup;
    }
    if (virDomainCpuSetParse((const char **)&mapstr, 0,
                             cpuset, maxcpu) < 0)
        goto cleanup;

    VIR_FREE(entry->def->cpumask);
    entry->def->cpumask = cpuset;
    entry->def->cpumasklen = maxcpu;
    cpuset = NULL;

    if (xenXMConfigSaveFile(domain->conn, entry->filename, entry->def) < 0)
        goto cleanup;

    ret = 0;

 cleanup:
    VIR_FREE(mapsave);
    VIR_FREE(cpuset);
    xenUnifiedUnlock(priv);
    return (ret);
}

/*
 * Find an inactive domain based on its name
 */
virDomainPtr xenXMDomainLookupByName(virConnectPtr conn, const char *domname) {
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;
    virDomainPtr ret = NULL;

    if (!VIR_IS_CONNECT(conn)) {
        xenXMError(VIR_ERR_INVALID_CONN, __FUNCTION__);
        return (NULL);
    }
    if (domname == NULL) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return (NULL);
    }

    priv = conn->privateData;
    xenUnifiedLock(priv);

    if (!xenInotifyActive(conn) && xenXMConfigCacheRefresh (conn) < 0)
        goto cleanup;

    if (!(filename = virHashLookup(priv->nameConfigMap, domname)))
        goto cleanup;

    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto cleanup;

    if (!(ret = virGetDomain(conn, domname, entry->def->uuid)))
        goto cleanup;

    /* Ensure its marked inactive, because may be cached
       handle to a previously active domain */
    ret->id = -1;

cleanup:
    xenUnifiedUnlock(priv);
    return (ret);
}


/*
 * Hash table iterator to search for a domain based on UUID
 */
static int xenXMDomainSearchForUUID(const void *payload, const void *name ATTRIBUTE_UNUSED, const void *data) {
    const unsigned char *wantuuid = (const unsigned char *)data;
    const xenXMConfCachePtr entry = (const xenXMConfCachePtr)payload;

    if (!memcmp(entry->def->uuid, wantuuid, VIR_UUID_BUFLEN))
        return (1);

    return (0);
}

/*
 * Find an inactive domain based on its UUID
 */
virDomainPtr xenXMDomainLookupByUUID(virConnectPtr conn,
                                     const unsigned char *uuid) {
    xenUnifiedPrivatePtr priv;
    xenXMConfCachePtr entry;
    virDomainPtr ret = NULL;

    if (!VIR_IS_CONNECT(conn)) {
        xenXMError(VIR_ERR_INVALID_CONN, __FUNCTION__);
        return (NULL);
    }
    if (uuid == NULL) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return (NULL);
    }

    priv = conn->privateData;
    xenUnifiedLock(priv);

    if (!xenInotifyActive(conn) && xenXMConfigCacheRefresh (conn) < 0)
        goto cleanup;

    if (!(entry = virHashSearch(priv->configCache, xenXMDomainSearchForUUID, (const void *)uuid)))
        goto cleanup;

    if (!(ret = virGetDomain(conn, entry->def->name, uuid)))
        goto cleanup;

    /* Ensure its marked inactive, because may be cached
       handle to a previously active domain */
    ret->id = -1;

cleanup:
    xenUnifiedUnlock(priv);
    return (ret);
}


/*
 * Start a domain from an existing defined config file
 */
int xenXMDomainCreate(virDomainPtr domain) {
    char *sexpr;
    int ret = -1;
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;

    priv = (xenUnifiedPrivatePtr) domain->conn->privateData;

    if (domain->id != -1)
        return (-1);

    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto error;

    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto error;

    if (!(sexpr = xenFormatSxpr(domain->conn, entry->def, priv->xendConfigVersion)))
        goto error;

    ret = xenDaemonDomainCreateXML(domain->conn, sexpr);
    VIR_FREE(sexpr);
    if (ret != 0)
        goto error;

    if ((ret = xenDaemonDomainLookupByName_ids(domain->conn, domain->name,
                                               entry->def->uuid)) < 0)
        goto error;
    domain->id = ret;

    if (xend_wait_for_devices(domain->conn, domain->name) < 0)
        goto error;

    if (xenDaemonDomainResume(domain) < 0)
        goto error;

    xenUnifiedUnlock(priv);
    return (0);

 error:
    if (domain->id != -1) {
        xenDaemonDomainDestroy(domain);
        domain->id = -1;
    }
    xenUnifiedUnlock(priv);
    return (-1);
}

/*
 * Create a config file for a domain, based on an XML
 * document describing its config
 */
virDomainPtr xenXMDomainDefineXML(virConnectPtr conn, const char *xml)
{
    virDomainPtr ret;
    char *filename;
    const char *oldfilename;
    virDomainDefPtr def = NULL;
    xenXMConfCachePtr entry = NULL;
    xenUnifiedPrivatePtr priv = (xenUnifiedPrivatePtr) conn->privateData;

    if (!VIR_IS_CONNECT(conn)) {
        xenXMError(VIR_ERR_INVALID_CONN, __FUNCTION__);
        return (NULL);
    }
    if (xml == NULL) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return (NULL);
    }
    if (conn->flags & VIR_CONNECT_RO)
        return (NULL);

    xenUnifiedLock(priv);

    if (!xenInotifyActive(conn) && xenXMConfigCacheRefresh (conn) < 0) {
        xenUnifiedUnlock(priv);
        return (NULL);
    }

    if (!(def = virDomainDefParseString(priv->caps, xml,
                                        VIR_DOMAIN_XML_INACTIVE))) {
        xenUnifiedUnlock(priv);
        return (NULL);
    }

    /*
     * check that if there is another domain defined with the same uuid
     * it has the same name
     */
    if ((entry = virHashSearch(priv->configCache, xenXMDomainSearchForUUID,
                               (const void *)&(def->uuid))) != NULL) {
        if ((entry->def != NULL) && (entry->def->name != NULL) &&
            (STRNEQ(def->name, entry->def->name))) {
            char uuidstr[VIR_UUID_STRING_BUFLEN];

            virUUIDFormat(entry->def->uuid, uuidstr);
            xenXMError(VIR_ERR_OPERATION_FAILED,
                       _("domain '%s' is already defined with uuid %s"),
                       entry->def->name, uuidstr);
            entry = NULL;
            goto error;
        }
        entry = NULL;
    }

    if (virHashLookup(priv->nameConfigMap, def->name)) {
        /* domain exists, we will overwrite it */

        if (!(oldfilename = (char *)virHashLookup(priv->nameConfigMap, def->name))) {
            xenXMError(VIR_ERR_INTERNAL_ERROR,
                       "%s", _("can't retrieve config filename for domain to overwrite"));
            goto error;
        }

        if (!(entry = virHashLookup(priv->configCache, oldfilename))) {
            xenXMError(VIR_ERR_INTERNAL_ERROR,
                       "%s", _("can't retrieve config entry for domain to overwrite"));
            goto error;
        }

        /* Remove the name -> filename mapping */
        if (virHashRemoveEntry(priv->nameConfigMap, def->name) < 0) {
            xenXMError(VIR_ERR_INTERNAL_ERROR,
                       "%s", _("failed to remove old domain from config map"));
            goto error;
        }

        /* Remove the config record itself */
        if (virHashRemoveEntry(priv->configCache, oldfilename) < 0) {
            xenXMError(VIR_ERR_INTERNAL_ERROR,
                       "%s", _("failed to remove old domain from config map"));
            goto error;
        }

        entry = NULL;
    }

    if (!(filename = virFileBuildPath(priv->configDir, def->name, NULL)))
        goto error;

    if (xenXMConfigSaveFile(conn, filename, def) < 0)
        goto error;

    if (VIR_ALLOC(entry) < 0) {
        virReportOOMError();
        goto error;
    }

    if ((entry->refreshedAt = time(NULL)) == ((time_t)-1)) {
        xenXMError(VIR_ERR_INTERNAL_ERROR,
                   "%s", _("unable to get current time"));
        goto error;
    }

    memmove(entry->filename, filename, PATH_MAX);
    entry->def = def;

    if (virHashAddEntry(priv->configCache, filename, entry) < 0) {
        xenXMError(VIR_ERR_INTERNAL_ERROR,
                   "%s", _("unable to store config file handle"));
        goto error;
    }

    if (virHashAddEntry(priv->nameConfigMap, def->name, entry->filename) < 0) {
        virHashSteal(priv->configCache, filename);
        xenXMError(VIR_ERR_INTERNAL_ERROR,
                   "%s", _("unable to store config file handle"));
        goto error;
    }

    ret = virGetDomain(conn, def->name, def->uuid);
    xenUnifiedUnlock(priv);
    VIR_FREE(filename);
    return (ret);

 error:
    VIR_FREE(filename);
    VIR_FREE(entry);
    virDomainDefFree(def);
    xenUnifiedUnlock(priv);
    return (NULL);
}

/*
 * Delete a domain from disk
 */
int xenXMDomainUndefine(virDomainPtr domain) {
    xenUnifiedPrivatePtr priv;
    const char *filename;
    xenXMConfCachePtr entry;
    int ret = -1;

    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return (-1);
    }

    if (domain->id != -1)
        return (-1);
    if (domain->conn->flags & VIR_CONNECT_RO)
        return (-1);

    priv = domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto cleanup;

    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto cleanup;

    if (unlink(entry->filename) < 0)
        goto cleanup;

    /* Remove the name -> filename mapping */
    if (virHashRemoveEntry(priv->nameConfigMap, domain->name) < 0)
        goto cleanup;

    /* Remove the config record itself */
    if (virHashRemoveEntry(priv->configCache, entry->filename) < 0)
        goto cleanup;

    ret = 0;

cleanup:
    xenUnifiedUnlock(priv);
    return ret;
}

struct xenXMListIteratorContext {
    virConnectPtr conn;
    int oom;
    int max;
    int count;
    char ** names;
};

static void xenXMListIterator(void *payload ATTRIBUTE_UNUSED, const void *name, void *data) {
    struct xenXMListIteratorContext *ctx = data;
    virDomainPtr dom = NULL;

    if (ctx->oom)
        return;

    if (ctx->count == ctx->max)
        return;

    dom = xenDaemonLookupByName(ctx->conn, name);
    if (!dom) {
        if (!(ctx->names[ctx->count] = strdup(name)))
            ctx->oom = 1;
        else
            ctx->count++;
    } else {
        virDomainFree(dom);
    }
}


/*
 * List all defined domains, filtered to remove any which
 * are currently running
 */
int xenXMListDefinedDomains(virConnectPtr conn, char **const names, int maxnames) {
    xenUnifiedPrivatePtr priv;
    struct xenXMListIteratorContext ctx;
    int i, ret = -1;

    if (!VIR_IS_CONNECT(conn)) {
        xenXMError(VIR_ERR_INVALID_CONN, __FUNCTION__);
        return (-1);
    }

    priv = conn->privateData;
    xenUnifiedLock(priv);

    if (!xenInotifyActive(conn) && xenXMConfigCacheRefresh (conn) < 0)
        goto cleanup;

    if (maxnames > virHashSize(priv->configCache))
        maxnames = virHashSize(priv->configCache);

    ctx.conn = conn;
    ctx.oom = 0;
    ctx.count = 0;
    ctx.max = maxnames;
    ctx.names = names;

    virHashForEach(priv->nameConfigMap, xenXMListIterator, &ctx);

    if (ctx.oom) {
        for (i = 0; i < ctx.count; i++)
            VIR_FREE(ctx.names[i]);

        virReportOOMError();
        goto cleanup;
    }

    ret = ctx.count;

cleanup:
    xenUnifiedUnlock(priv);
    return ret;
}

/*
 * Return the maximum number of defined domains - not filtered
 * based on number running
 */
int xenXMNumOfDefinedDomains(virConnectPtr conn) {
    xenUnifiedPrivatePtr priv;
    int ret = -1;

    if (!VIR_IS_CONNECT(conn)) {
        xenXMError(VIR_ERR_INVALID_CONN, __FUNCTION__);
        return (-1);
    }

    priv = conn->privateData;
    xenUnifiedLock(priv);

    if (!xenInotifyActive(conn) && xenXMConfigCacheRefresh (conn) < 0)
        goto cleanup;

    ret = virHashSize(priv->nameConfigMap);

cleanup:
    xenUnifiedUnlock(priv);
    return ret;
}


/**
 * xenXMDomainAttachDeviceFlags:
 * @domain: pointer to domain object
 * @xml: pointer to XML description of device
 * @flags: an OR'ed set of virDomainDeviceModifyFlags
 *
 * Create a virtual device attachment to backend.
 * XML description is translated into config file.
 * This driver only supports device allocation to
 * persisted config.
 *
 * Returns 0 in case of success, -1 in case of failure.
 */
static int
xenXMDomainAttachDeviceFlags(virDomainPtr domain, const char *xml,
                             unsigned int flags) {
    const char *filename = NULL;
    xenXMConfCachePtr entry = NULL;
    int ret = -1;
    virDomainDeviceDefPtr dev = NULL;
    virDomainDefPtr def;
    xenUnifiedPrivatePtr priv;

    if ((!domain) || (!domain->conn) || (!domain->name) || (!xml)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return -1;
    }

    if (domain->conn->flags & VIR_CONNECT_RO)
        return -1;

    if ((flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE) ||
        (domain->id != -1 && (flags & VIR_DOMAIN_DEVICE_MODIFY_CURRENT))) {
        xenXMError(VIR_ERR_OPERATION_INVALID, "%s",
                   _("Xm driver only supports modifying persistent config"));
        return -1;
    }

    priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto cleanup;
    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto cleanup;
    def = entry->def;

    if (!(dev = virDomainDeviceDefParse(priv->caps,
                                        entry->def,
                                        xml, VIR_DOMAIN_XML_INACTIVE)))
        goto cleanup;

    switch (dev->type) {
    case VIR_DOMAIN_DEVICE_DISK:
    {
        if (virDomainDiskInsert(def, dev->data.disk) < 0) {
            virReportOOMError();
            goto cleanup;
        }
        dev->data.disk = NULL;
    }
    break;

    case VIR_DOMAIN_DEVICE_NET:
    {
        if (VIR_REALLOC_N(def->nets, def->nnets+1) < 0) {
            virReportOOMError();
            goto cleanup;
        }
        def->nets[def->nnets++] = dev->data.net;
        dev->data.net = NULL;
        break;
    }

    default:
        xenXMError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                   _("Xm driver only supports adding disk or network devices"));
        goto cleanup;
    }

    /* If this fails, should we try to undo our changes to the
     * in-memory representation of the config file. I say not!
     */
    if (xenXMConfigSaveFile(domain->conn, entry->filename, entry->def) < 0)
        goto cleanup;

    ret = 0;

 cleanup:
    virDomainDeviceDefFree(dev);
    xenUnifiedUnlock(priv);
    return ret;
}


/**
 * xenXMDomainDetachDeviceFlags:
 * @domain: pointer to domain object
 * @xml: pointer to XML description of device
 * @flags: an OR'ed set of virDomainDeviceModifyFlags
 *
 * Destroy a virtual device attachment to backend.
 * This driver only supports device deallocation from
 * persisted config.
 *
 * Returns 0 in case of success, -1 in case of failure.
 */
static int
xenXMDomainDetachDeviceFlags(virDomainPtr domain, const char *xml,
                             unsigned int flags) {
    const char *filename = NULL;
    xenXMConfCachePtr entry = NULL;
    virDomainDeviceDefPtr dev = NULL;
    virDomainDefPtr def;
    int ret = -1;
    int i;
    xenUnifiedPrivatePtr priv;

    if ((!domain) || (!domain->conn) || (!domain->name) || (!xml)) {
        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
        return -1;
    }


    if (domain->conn->flags & VIR_CONNECT_RO)
        return -1;

    if ((flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE) ||
        (domain->id != -1 && (flags & VIR_DOMAIN_DEVICE_MODIFY_CURRENT))) {
        xenXMError(VIR_ERR_OPERATION_INVALID, "%s",
                   _("Xm driver only supports modifying persistent config"));
        return -1;
    }

    priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
    xenUnifiedLock(priv);

    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
        goto cleanup;
    if (!(entry = virHashLookup(priv->configCache, filename)))
        goto cleanup;
    def = entry->def;

    if (!(dev = virDomainDeviceDefParse(priv->caps,
                                        entry->def,
                                        xml, VIR_DOMAIN_XML_INACTIVE)))
        goto cleanup;

    switch (dev->type) {
    case VIR_DOMAIN_DEVICE_DISK:
    {
        for (i = 0 ; i < def->ndisks ; i++) {
            if (def->disks[i]->dst &&
                dev->data.disk->dst &&
                STREQ(def->disks[i]->dst, dev->data.disk->dst)) {
                virDomainDiskDefFree(def->disks[i]);
                if (i < (def->ndisks - 1))
                    memmove(def->disks + i,
                            def->disks + i + 1,
                            sizeof(*def->disks) *
                            (def->ndisks - (i + 1)));
                def->ndisks--;
                break;
            }
        }
        break;
    }

    case VIR_DOMAIN_DEVICE_NET:
    {
        for (i = 0 ; i < def->nnets ; i++) {
            if (!memcmp(def->nets[i]->mac,
                        dev->data.net->mac,
                        sizeof(def->nets[i]->mac))) {
                virDomainNetDefFree(def->nets[i]);
                if (i < (def->nnets - 1))
                    memmove(def->nets + i,
                            def->nets + i + 1,
                            sizeof(*def->nets) *
                            (def->nnets - (i + 1)));
                def->nnets--;
                break;
            }
        }
        break;
    }
    default:
        xenXMError(VIR_ERR_XML_ERROR,
                   "%s", _("unknown device"));
        goto cleanup;
    }

    /* If this fails, should we try to undo our changes to the
     * in-memory representation of the config file. I say not!
     */
    if (xenXMConfigSaveFile(domain->conn, entry->filename, entry->def) < 0)
        goto cleanup;

    ret = 0;

 cleanup:
    virDomainDeviceDefFree(dev);
    xenUnifiedUnlock(priv);
    return (ret);
}

int
xenXMDomainBlockPeek (virDomainPtr dom ATTRIBUTE_UNUSED,
                      const char *path ATTRIBUTE_UNUSED,
                      unsigned long long offset ATTRIBUTE_UNUSED,
                      size_t size ATTRIBUTE_UNUSED,
                      void *buffer ATTRIBUTE_UNUSED)
{
    xenXMError(VIR_ERR_NO_SUPPORT, __FUNCTION__);
    return -1;
}


static char *xenXMAutostartLinkName(virDomainPtr dom)
{
    char *ret;
    if (virAsprintf(&ret, "/etc/xen/auto/%s", dom->name) < 0)
        return NULL;
    return ret;
}

static char *xenXMDomainConfigName(virDomainPtr dom)
{
    char *ret;
    if (virAsprintf(&ret, "/etc/xen/%s", dom->name) < 0)
        return NULL;
    return ret;
}

int xenXMDomainGetAutostart(virDomainPtr dom, int *autostart)
{
    char *linkname = xenXMAutostartLinkName(dom);
    char *config = xenXMDomainConfigName(dom);
    int ret = -1;

    if (!linkname || !config) {
        virReportOOMError();
        goto cleanup;
    }

    *autostart = virFileLinkPointsTo(linkname, config);
    if (*autostart < 0) {
        virReportSystemError(errno,
                             _("cannot check link %s points to config %s"),
                             linkname, config);
        goto cleanup;
    }

    ret = 0;

cleanup:
    VIR_FREE(linkname);
    VIR_FREE(config);
    return ret;
}


int xenXMDomainSetAutostart(virDomainPtr dom, int autostart)
{
    char *linkname = xenXMAutostartLinkName(dom);
    char *config = xenXMDomainConfigName(dom);
    int ret = -1;

    if (!linkname || !config) {
        virReportOOMError();
        goto cleanup;
    }

    if (autostart) {
        if (symlink(config, linkname) < 0 &&
            errno != EEXIST) {
            virReportSystemError(errno,
                                 _("failed to create link %s to %s"),
                                 config, linkname);
            goto cleanup;
        }
    } else {
        if (unlink(linkname)  < 0 &&
            errno != ENOENT) {
            virReportSystemError(errno,
                                 _("failed to remove link %s"),
                                 linkname);
            goto cleanup;
        }
    }
    ret = 0;

cleanup:
    VIR_FREE(linkname);
    VIR_FREE(config);

    return ret;
}