s3:registry: fix race in reg_setvalue that could lead to data corruption

[Samba/vl.git] / source3 / registry / reg_api.c

/*
 *  Unix SMB/CIFS implementation.
 *  Virtual Windows Registry Layer
 *  Copyright (C) Volker Lendecke 2006
 *  Copyright (C) Michael Adam 2007-2010
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

/* Attempt to wrap the existing API in a more winreg.idl-like way */

/*
 * Here is a list of winreg.idl functions and corresponding implementations
 * provided here:
 *
 * 0x00         winreg_OpenHKCR
 * 0x01         winreg_OpenHKCU
 * 0x02         winreg_OpenHKLM
 * 0x03         winreg_OpenHKPD
 * 0x04         winreg_OpenHKU
 * 0x05         winreg_CloseKey
 * 0x06         winreg_CreateKey                        reg_createkey
 * 0x07         winreg_DeleteKey                        reg_deletekey
 * 0x08         winreg_DeleteValue                      reg_deletevalue
 * 0x09         winreg_EnumKey                          reg_enumkey
 * 0x0a         winreg_EnumValue                        reg_enumvalue
 * 0x0b         winreg_FlushKey
 * 0x0c         winreg_GetKeySecurity                   reg_getkeysecurity
 * 0x0d         winreg_LoadKey
 * 0x0e         winreg_NotifyChangeKeyValue
 * 0x0f         winreg_OpenKey                          reg_openkey
 * 0x10         winreg_QueryInfoKey                     reg_queryinfokey
 * 0x11         winreg_QueryValue                       reg_queryvalue
 * 0x12         winreg_ReplaceKey
 * 0x13         winreg_RestoreKey                       reg_restorekey
 * 0x14         winreg_SaveKey                          reg_savekey
 * 0x15         winreg_SetKeySecurity                   reg_setkeysecurity
 * 0x16         winreg_SetValue                         reg_setvalue
 * 0x17         winreg_UnLoadKey
 * 0x18         winreg_InitiateSystemShutdown
 * 0x19         winreg_AbortSystemShutdown
 * 0x1a         winreg_GetVersion                       reg_getversion
 * 0x1b         winreg_OpenHKCC
 * 0x1c         winreg_OpenHKDD
 * 0x1d         winreg_QueryMultipleValues              reg_querymultiplevalues
 * 0x1e         winreg_InitiateSystemShutdownEx
 * 0x1f         winreg_SaveKeyEx
 * 0x20         winreg_OpenHKPT
 * 0x21         winreg_OpenHKPN
 * 0x22         winreg_QueryMultipleValues2             reg_querymultiplevalues
 *
 */

#include "includes.h"
#include "registry.h"
#include "reg_api.h"
#include "reg_cachehook.h"
#include "reg_backend_db.h"
#include "reg_dispatcher.h"
#include "reg_objects.h"
#include "../librpc/gen_ndr/ndr_security.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_REGISTRY


/**********************************************************************
 * Helper functions
 **********************************************************************/

static WERROR fill_value_cache(struct registry_key *key)
{
        WERROR werr;

        if (key->values != NULL) {
                if (!reg_values_need_update(key->key, key->values)) {
                        return WERR_OK;
                }
        }

        TALLOC_FREE(key->values);
        werr = regval_ctr_init(key, &(key->values));
        W_ERROR_NOT_OK_RETURN(werr);

        if (fetch_reg_values(key->key, key->values) == -1) {
                TALLOC_FREE(key->values);
                return WERR_BADFILE;
        }

        return WERR_OK;
}

static WERROR fill_subkey_cache(struct registry_key *key)
{
        WERROR werr;

        if (key->subkeys != NULL) {
                if (!reg_subkeys_need_update(key->key, key->subkeys)) {
                        return WERR_OK;
                }
        }

        TALLOC_FREE(key->subkeys);
        werr = regsubkey_ctr_init(key, &(key->subkeys));
        W_ERROR_NOT_OK_RETURN(werr);

        if (fetch_reg_keys(key->key, key->subkeys) == -1) {
                TALLOC_FREE(key->subkeys);
                return WERR_NO_MORE_ITEMS;
        }

        return WERR_OK;
}

static int regkey_destructor(struct registry_key_handle *key)
{
        return regdb_close();
}

static WERROR regkey_open_onelevel(TALLOC_CTX *mem_ctx, 
                                   struct registry_key *parent,
                                   const char *name,
                                   const struct security_token *token,
                                   uint32 access_desired,
                                   struct registry_key **pregkey)
{
        WERROR          result = WERR_OK;
        struct registry_key *regkey;
        struct registry_key_handle *key;
        struct regsubkey_ctr    *subkeys = NULL;

        DEBUG(7,("regkey_open_onelevel: name = [%s]\n", name));

        SMB_ASSERT(strchr(name, '\\') == NULL);

        if (!(regkey = talloc_zero(mem_ctx, struct registry_key)) ||
            !(regkey->token = dup_nt_token(regkey, token)) ||
            !(regkey->key = talloc_zero(regkey, struct registry_key_handle)))
        {
                result = WERR_NOMEM;
                goto done;
        }

        if ( !(W_ERROR_IS_OK(result = regdb_open())) ) {
                goto done;
        }

        key = regkey->key;
        talloc_set_destructor(key, regkey_destructor);

        /* initialization */

        key->type = REG_KEY_GENERIC;

        if (name[0] == '\0') {
                /*
                 * Open a copy of the parent key
                 */
                if (!parent) {
                        result = WERR_BADFILE;
                        goto done;
                }
                key->name = talloc_strdup(key, parent->key->name);
        }
        else {
                /*
                 * Normal subkey open
                 */
                key->name = talloc_asprintf(key, "%s%s%s",
                                            parent ? parent->key->name : "",
                                            parent ? "\\": "",
                                            name);
        }

        if (key->name == NULL) {
                result = WERR_NOMEM;
                goto done;
        }

        /* Tag this as a Performance Counter Key */

        if( strncasecmp_m(key->name, KEY_HKPD, strlen(KEY_HKPD)) == 0 )
                key->type = REG_KEY_HKPD;

        /* Look up the table of registry I/O operations */

        if ( !(key->ops = reghook_cache_find( key->name )) ) {
                DEBUG(0,("reg_open_onelevel: Failed to assign "
                         "registry_ops to [%s]\n", key->name ));
                result = WERR_BADFILE;
                goto done;
        }

        /* check if the path really exists; failed is indicated by -1 */
        /* if the subkey count failed, bail out */

        result = regsubkey_ctr_init(key, &subkeys);
        if (!W_ERROR_IS_OK(result)) {
                goto done;
        }

        if ( fetch_reg_keys( key, subkeys ) == -1 )  {
                result = WERR_BADFILE;
                goto done;
        }

        TALLOC_FREE( subkeys );

        if ( !regkey_access_check( key, access_desired, &key->access_granted,
                                   token ) ) {
                result = WERR_ACCESS_DENIED;
                goto done;
        }

        *pregkey = regkey;
        result = WERR_OK;

done:
        if ( !W_ERROR_IS_OK(result) ) {
                TALLOC_FREE(regkey);
        }

        return result;
}

WERROR reg_openhive(TALLOC_CTX *mem_ctx, const char *hive,
                    uint32 desired_access,
                    const struct security_token *token,
                    struct registry_key **pkey)
{
        SMB_ASSERT(hive != NULL);
        SMB_ASSERT(hive[0] != '\0');
        SMB_ASSERT(strchr(hive, '\\') == NULL);

        return regkey_open_onelevel(mem_ctx, NULL, hive, token, desired_access,
                                    pkey);
}


/**********************************************************************
 * The API functions
 **********************************************************************/

WERROR reg_openkey(TALLOC_CTX *mem_ctx, struct registry_key *parent,
                   const char *name, uint32 desired_access,
                   struct registry_key **pkey)
{
        struct registry_key *direct_parent = parent;
        WERROR err;
        char *p, *path, *to_free;
        size_t len;

        if (!(path = SMB_STRDUP(name))) {
                return WERR_NOMEM;
        }
        to_free = path;

        len = strlen(path);

        if ((len > 0) && (path[len-1] == '\\')) {
                path[len-1] = '\0';
        }

        while ((p = strchr(path, '\\')) != NULL) {
                char *name_component;
                struct registry_key *tmp;

                if (!(name_component = SMB_STRNDUP(path, (p - path)))) {
                        err = WERR_NOMEM;
                        goto error;
                }

                err = regkey_open_onelevel(mem_ctx, direct_parent,
                                           name_component, parent->token,
                                           KEY_ENUMERATE_SUB_KEYS, &tmp);
                SAFE_FREE(name_component);

                if (!W_ERROR_IS_OK(err)) {
                        goto error;
                }
                if (direct_parent != parent) {
                        TALLOC_FREE(direct_parent);
                }

                direct_parent = tmp;
                path = p+1;
        }

        err = regkey_open_onelevel(mem_ctx, direct_parent, path, parent->token,
                                   desired_access, pkey);
 error:
        if (direct_parent != parent) {
                TALLOC_FREE(direct_parent);
        }
        SAFE_FREE(to_free);
        return err;
}

WERROR reg_enumkey(TALLOC_CTX *mem_ctx, struct registry_key *key,
                   uint32 idx, char **name, NTTIME *last_write_time)
{
        WERROR err;

        if (!(key->key->access_granted & KEY_ENUMERATE_SUB_KEYS)) {
                return WERR_ACCESS_DENIED;
        }

        if (!W_ERROR_IS_OK(err = fill_subkey_cache(key))) {
                return err;
        }

        if (idx >= regsubkey_ctr_numkeys(key->subkeys)) {
                return WERR_NO_MORE_ITEMS;
        }

        if (!(*name = talloc_strdup(mem_ctx,
                        regsubkey_ctr_specific_key(key->subkeys, idx))))
        {
                return WERR_NOMEM;
        }

        if (last_write_time) {
                *last_write_time = 0;
        }

        return WERR_OK;
}

WERROR reg_enumvalue(TALLOC_CTX *mem_ctx, struct registry_key *key,
                     uint32 idx, char **pname, struct registry_value **pval)
{
        struct registry_value *val;
        struct regval_blob *blob;
        WERROR err;

        if (!(key->key->access_granted & KEY_QUERY_VALUE)) {
                return WERR_ACCESS_DENIED;
        }

        if (!(W_ERROR_IS_OK(err = fill_value_cache(key)))) {
                return err;
        }

        if (idx >= regval_ctr_numvals(key->values)) {
                return WERR_NO_MORE_ITEMS;
        }

        blob = regval_ctr_specific_value(key->values, idx);

        val = talloc_zero(mem_ctx, struct registry_value);
        if (val == NULL) {
                return WERR_NOMEM;
        }

        val->type = regval_type(blob);
        val->data = data_blob_talloc(mem_ctx, regval_data_p(blob), regval_size(blob));

        if (pname
            && !(*pname = talloc_strdup(
                         mem_ctx, regval_name(blob)))) {
                TALLOC_FREE(val);
                return WERR_NOMEM;
        }

        *pval = val;
        return WERR_OK;
}

static WERROR reg_enumvalue_nocachefill(TALLOC_CTX *mem_ctx,
                                        struct registry_key *key,
                                        uint32 idx, char **pname,
                                        struct registry_value **pval)
{
        struct registry_value *val;
        struct regval_blob *blob;

        if (!(key->key->access_granted & KEY_QUERY_VALUE)) {
                return WERR_ACCESS_DENIED;
        }

        if (idx >= regval_ctr_numvals(key->values)) {
                return WERR_NO_MORE_ITEMS;
        }

        blob = regval_ctr_specific_value(key->values, idx);

        val = talloc_zero(mem_ctx, struct registry_value);
        if (val == NULL) {
                return WERR_NOMEM;
        }

        val->type = regval_type(blob);
        val->data = data_blob_talloc(mem_ctx, regval_data_p(blob), regval_size(blob));

        if (pname
            && !(*pname = talloc_strdup(
                         mem_ctx, regval_name(blob)))) {
                TALLOC_FREE(val);
                return WERR_NOMEM;
        }

        *pval = val;
        return WERR_OK;
}

WERROR reg_queryvalue(TALLOC_CTX *mem_ctx, struct registry_key *key,
                      const char *name, struct registry_value **pval)
{
        WERROR err;
        uint32 i;

        if (!(key->key->access_granted & KEY_QUERY_VALUE)) {
                return WERR_ACCESS_DENIED;
        }

        if (!(W_ERROR_IS_OK(err = fill_value_cache(key)))) {
                return err;
        }

        for (i=0; i < regval_ctr_numvals(key->values); i++) {
                struct regval_blob *blob;
                blob = regval_ctr_specific_value(key->values, i);
                if (strequal(regval_name(blob), name)) {
                        /*
                         * don't use reg_enumvalue here:
                         * re-reading the values from the disk
                         * would change the indexing and break
                         * this function.
                         */
                        return reg_enumvalue_nocachefill(mem_ctx, key, i,
                                                         NULL, pval);
                }
        }

        return WERR_BADFILE;
}

WERROR reg_querymultiplevalues(TALLOC_CTX *mem_ctx,
                               struct registry_key *key,
                               uint32_t num_names,
                               const char **names,
                               uint32_t *pnum_vals,
                               struct registry_value **pvals)
{
        WERROR err;
        uint32_t i, n, found = 0;
        struct registry_value *vals;

        if (num_names == 0) {
                return WERR_OK;
        }

        if (!(key->key->access_granted & KEY_QUERY_VALUE)) {
                return WERR_ACCESS_DENIED;
        }

        if (!(W_ERROR_IS_OK(err = fill_value_cache(key)))) {
                return err;
        }

        vals = talloc_zero_array(mem_ctx, struct registry_value, num_names);
        if (vals == NULL) {
                return WERR_NOMEM;
        }

        for (n=0; n < num_names; n++) {
                for (i=0; i < regval_ctr_numvals(key->values); i++) {
                        struct regval_blob *blob;
                        blob = regval_ctr_specific_value(key->values, i);
                        if (strequal(regval_name(blob), names[n])) {
                                struct registry_value *v;
                                err = reg_enumvalue(mem_ctx, key, i, NULL, &v);
                                if (!W_ERROR_IS_OK(err)) {
                                        return err;
                                }
                                vals[n] = *v;
                                found++;
                        }
                }
        }

        *pvals = vals;
        *pnum_vals = found;

        return WERR_OK;
}

WERROR reg_queryinfokey(struct registry_key *key, uint32_t *num_subkeys,
                        uint32_t *max_subkeylen, uint32_t *max_subkeysize, 
                        uint32_t *num_values, uint32_t *max_valnamelen, 
                        uint32_t *max_valbufsize, uint32_t *secdescsize,
                        NTTIME *last_changed_time)
{
        uint32 i, max_size;
        size_t max_len;
        TALLOC_CTX *mem_ctx;
        WERROR err;
        struct security_descriptor *secdesc;

        if (!(key->key->access_granted & KEY_QUERY_VALUE)) {
                return WERR_ACCESS_DENIED;
        }

        if (!W_ERROR_IS_OK(fill_subkey_cache(key)) ||
            !W_ERROR_IS_OK(fill_value_cache(key))) {
                return WERR_BADFILE;
        }

        max_len = 0;
        for (i=0; i< regsubkey_ctr_numkeys(key->subkeys); i++) {
                max_len = MAX(max_len,
                        strlen(regsubkey_ctr_specific_key(key->subkeys, i)));
        }

        *num_subkeys = regsubkey_ctr_numkeys(key->subkeys);
        *max_subkeylen = max_len;
        *max_subkeysize = 0;    /* Class length? */

        max_len = 0;
        max_size = 0;
        for (i=0; i < regval_ctr_numvals(key->values); i++) {
                struct regval_blob *blob;
                blob = regval_ctr_specific_value(key->values, i);
                max_len = MAX(max_len, strlen(regval_name(blob)));
                max_size = MAX(max_size, regval_size(blob));
        }

        *num_values = regval_ctr_numvals(key->values);
        *max_valnamelen = max_len;
        *max_valbufsize = max_size;

        if (!(mem_ctx = talloc_new(key))) {
                return WERR_NOMEM;
        }

        err = regkey_get_secdesc(mem_ctx, key->key, &secdesc);
        if (!W_ERROR_IS_OK(err)) {
                TALLOC_FREE(mem_ctx);
                return err;
        }

        *secdescsize = ndr_size_security_descriptor(secdesc, 0);
        TALLOC_FREE(mem_ctx);

        *last_changed_time = 0;

        return WERR_OK;
}

WERROR reg_createkey(TALLOC_CTX *ctx, struct registry_key *parent,
                     const char *subkeypath, uint32 desired_access,
                     struct registry_key **pkey,
                     enum winreg_CreateAction *paction)
{
        struct registry_key *key = parent;
        struct registry_key *create_parent;
        TALLOC_CTX *mem_ctx;
        char *path, *end;
        WERROR err;

        if (!(mem_ctx = talloc_new(ctx))) return WERR_NOMEM;

        if (!(path = talloc_strdup(mem_ctx, subkeypath))) {
                err = WERR_NOMEM;
                goto done;
        }

        while ((end = strchr(path, '\\')) != NULL) {
                struct registry_key *tmp;
                enum winreg_CreateAction action;

                *end = '\0';

                err = reg_createkey(mem_ctx, key, path,
                                    KEY_ENUMERATE_SUB_KEYS, &tmp, &action);
                if (!W_ERROR_IS_OK(err)) {
                        goto done;
                }

                if (key != parent) {
                        TALLOC_FREE(key);
                }

                key = tmp;
                path = end+1;
        }

        /*
         * At this point, "path" contains the one-element subkey of "key". We
         * can try to open it.
         */

        err = reg_openkey(ctx, key, path, desired_access, pkey);
        if (W_ERROR_IS_OK(err)) {
                if (paction != NULL) {
                        *paction = REG_OPENED_EXISTING_KEY;
                }
                goto done;
        }

        if (!W_ERROR_EQUAL(err, WERR_BADFILE)) {
                /*
                 * Something but "notfound" has happened, so bail out
                 */
                goto done;
        }

        /*
         * We have to make a copy of the current key, as we opened it only
         * with ENUM_SUBKEY access.
         */

        err = reg_openkey(mem_ctx, key, "", KEY_CREATE_SUB_KEY,
                          &create_parent);
        if (!W_ERROR_IS_OK(err)) {
                goto done;
        }

        /*
         * Actually create the subkey
         */

        err = fill_subkey_cache(create_parent);
        if (!W_ERROR_IS_OK(err)) goto done;

        err = create_reg_subkey(key->key, path);
        W_ERROR_NOT_OK_GOTO_DONE(err);

        /*
         * Now open the newly created key
         */

        err = reg_openkey(ctx, create_parent, path, desired_access, pkey);
        if (W_ERROR_IS_OK(err) && (paction != NULL)) {
                *paction = REG_CREATED_NEW_KEY;
        }

 done:
        TALLOC_FREE(mem_ctx);
        return err;
}

static WERROR reg_deletekey_internal(TALLOC_CTX *mem_ctx,
                                     struct registry_key *parent,
                                     const char *path, bool lazy)
{
        WERROR err;
        char *name, *end;
        struct registry_key *key;
        name = talloc_strdup(mem_ctx, path);
        if (name == NULL) {
                err = WERR_NOMEM;
                goto done;
        }

        /* no subkeys - proceed with delete */
        end = strrchr(name, '\\');
        if (end != NULL) {
                *end = '\0';

                err = reg_openkey(mem_ctx, parent, name,
                                  KEY_CREATE_SUB_KEY, &key);
                W_ERROR_NOT_OK_GOTO_DONE(err);

                parent = key;
                name = end+1;
        }

        if (name[0] == '\0') {
                err = WERR_INVALID_PARAM;
                goto done;
        }

        err = delete_reg_subkey(parent->key, name, lazy);

done:
        return err;
}

WERROR reg_deletekey(struct registry_key *parent, const char *path)
{
        WERROR err;
        struct registry_key *key;
        TALLOC_CTX *mem_ctx = talloc_stackframe();

        /* check if the key has subkeys */
        err = reg_openkey(mem_ctx, parent, path, REG_KEY_READ, &key);
        W_ERROR_NOT_OK_GOTO_DONE(err);

        err = fill_subkey_cache(key);
        W_ERROR_NOT_OK_GOTO_DONE(err);

        if (regsubkey_ctr_numkeys(key->subkeys) > 0) {
                err = WERR_ACCESS_DENIED;
                goto done;
        }
        err = reg_deletekey_internal(mem_ctx, parent, path, false);
done:
        TALLOC_FREE(mem_ctx);
        return err;
}


WERROR reg_setvalue(struct registry_key *key, const char *name,
                    const struct registry_value *val)
{
        struct regval_blob *existing;
        WERROR err;
        int res;

        if (!(key->key->access_granted & KEY_SET_VALUE)) {
                return WERR_ACCESS_DENIED;
        }

        err = regdb_transaction_start();
        if (!W_ERROR_IS_OK(err)) {
                DEBUG(0, ("reg_setvalue: Failed to start transaction: %s\n",
                          win_errstr(err)));
                return err;
        }

        err = fill_value_cache(key);
        if (!W_ERROR_IS_OK(err)) {
                DEBUG(0, ("reg_setvalue: Error filling value cache: %s\n", win_errstr(err)));
                goto done;
        }

        existing = regval_ctr_getvalue(key->values, name);

        if ((existing != NULL) &&
            (regval_size(existing) == val->data.length) &&
            (memcmp(regval_data_p(existing), val->data.data,
                    val->data.length) == 0))
        {
                err = WERR_OK;
                goto done;
        }

        res = regval_ctr_addvalue(key->values, name, val->type,
                                  val->data.data, val->data.length);

        if (res == 0) {
                TALLOC_FREE(key->values);
                err = WERR_NOMEM;
                goto done;
        }

        if (!store_reg_values(key->key, key->values)) {
                TALLOC_FREE(key->values);
                DEBUG(0, ("reg_setvalue: store_reg_values failed\n"));
                err = WERR_REG_IO_FAILURE;
                goto done;
        }

        err = WERR_OK;

done:
        if (W_ERROR_IS_OK(err)) {
                err = regdb_transaction_commit();
                if (!W_ERROR_IS_OK(err)) {
                        DEBUG(0, ("reg_setvalue: Error committing transaction: %s\n", win_errstr(err)));
                }
        } else {
                WERROR err1 = regdb_transaction_cancel();
                if (!W_ERROR_IS_OK(err1)) {
                        DEBUG(0, ("reg_setvalue: Error cancelling transaction: %s\n", win_errstr(err1)));
                }
        }

        return err;
}

static WERROR reg_value_exists(struct registry_key *key, const char *name)
{
        struct regval_blob *blob;

        blob = regval_ctr_getvalue(key->values, name);

        if (blob == NULL) {
                return WERR_BADFILE;
        } else {
                return WERR_OK;
        }
}

WERROR reg_deletevalue(struct registry_key *key, const char *name)
{
        WERROR err;

        if (!(key->key->access_granted & KEY_SET_VALUE)) {
                return WERR_ACCESS_DENIED;
        }

        if (!W_ERROR_IS_OK(err = fill_value_cache(key))) {
                return err;
        }

        err = reg_value_exists(key, name);
        if (!W_ERROR_IS_OK(err)) {
                return err;
        }

        regval_ctr_delvalue(key->values, name);

        if (!store_reg_values(key->key, key->values)) {
                TALLOC_FREE(key->values);
                return WERR_REG_IO_FAILURE;
        }

        return WERR_OK;
}

WERROR reg_getkeysecurity(TALLOC_CTX *mem_ctx, struct registry_key *key,
                          struct security_descriptor **psecdesc)
{
        return regkey_get_secdesc(mem_ctx, key->key, psecdesc);
}

WERROR reg_setkeysecurity(struct registry_key *key,
                          struct security_descriptor *psecdesc)
{
        return regkey_set_secdesc(key->key, psecdesc);
}

WERROR reg_getversion(uint32_t *version)
{
        if (version == NULL) {
                return WERR_INVALID_PARAM;
        }

        *version = 0x00000005; /* Windows 2000 registry API version */
        return WERR_OK;
}

/**********************************************************************
 * Higher level utility functions
 **********************************************************************/

WERROR reg_deleteallvalues(struct registry_key *key)
{
        WERROR err;
        int i;

        if (!(key->key->access_granted & KEY_SET_VALUE)) {
                return WERR_ACCESS_DENIED;
        }

        if (!W_ERROR_IS_OK(err = fill_value_cache(key))) {
                return err;
        }

        for (i=0; i < regval_ctr_numvals(key->values); i++) {
                struct regval_blob *blob;
                blob = regval_ctr_specific_value(key->values, i);
                regval_ctr_delvalue(key->values, regval_name(blob));
        }

        if (!store_reg_values(key->key, key->values)) {
                TALLOC_FREE(key->values);
                return WERR_REG_IO_FAILURE;
        }

        return WERR_OK;
}

/*
 * Utility function to delete a registry key with all its subkeys.
 * Note that reg_deletekey returns ACCESS_DENIED when called on a
 * key that has subkeys.
 */
static WERROR reg_deletekey_recursive_internal(struct registry_key *parent,
                                               const char *path,
                                               bool del_key, bool lazy)
{
        WERROR werr = WERR_OK;
        struct registry_key *key;
        char *subkey_name = NULL;
        uint32 i;
        TALLOC_CTX *mem_ctx = talloc_stackframe();

        DEBUG(5, ("reg_deletekey_recursive_internal: deleting '%s' from '%s'\n",
                  path, parent->key->name));

        /* recurse through subkeys first */
        werr = reg_openkey(mem_ctx, parent, path, REG_KEY_ALL, &key);
        if (!W_ERROR_IS_OK(werr)) {
                DEBUG(3, ("reg_deletekey_recursive_internal: error opening "
                          "subkey '%s' of '%s': '%s'\n",
                          path, parent->key->name, win_errstr(werr)));
                goto done;
        }

        werr = fill_subkey_cache(key);
        W_ERROR_NOT_OK_GOTO_DONE(werr);

        /*
         * loop from top to bottom for perfomance:
         * this way, we need to rehash the regsubkey containers less
         */
        for (i = regsubkey_ctr_numkeys(key->subkeys) ; i > 0; i--) {
                subkey_name = regsubkey_ctr_specific_key(key->subkeys, i-1);
                werr = reg_deletekey_recursive_internal(key, subkey_name, true, del_key);
                W_ERROR_NOT_OK_GOTO_DONE(werr);
        }

        if (del_key) {
                /* now delete the actual key */
                werr = reg_deletekey_internal(mem_ctx, parent, path, lazy);
        }

done:

        DEBUG(5, ("reg_deletekey_recursive_internal: done deleting '%s' from "
                  "'%s': %s\n",
                  path, parent->key->name, win_errstr(werr)));
        TALLOC_FREE(mem_ctx);
        return werr;
}

static WERROR reg_deletekey_recursive_trans(struct registry_key *parent,
                                            const char *path,
                                            bool del_key)
{
        WERROR werr;

        werr = regdb_transaction_start();
        if (!W_ERROR_IS_OK(werr)) {
                DEBUG(0, ("reg_deletekey_recursive_trans: "
                          "error starting transaction: %s\n",
                          win_errstr(werr)));
                return werr;
        }

        werr = reg_deletekey_recursive_internal(parent, path, del_key, false);

        if (!W_ERROR_IS_OK(werr)) {
                WERROR werr2;

                DEBUG(1, (__location__ " failed to delete key '%s' from key "
                          "'%s': %s\n", path, parent->key->name,
                          win_errstr(werr)));

                werr2 = regdb_transaction_cancel();
                if (!W_ERROR_IS_OK(werr2)) {
                        DEBUG(0, ("reg_deletekey_recursive_trans: "
                                  "error cancelling transaction: %s\n",
                                  win_errstr(werr2)));
                        /*
                         * return the original werr or the
                         * error from cancelling the transaction?
                         */
                }
        } else {
                werr = regdb_transaction_commit();
                if (!W_ERROR_IS_OK(werr)) {
                        DEBUG(0, ("reg_deletekey_recursive_trans: "
                                  "error committing transaction: %s\n",
                                  win_errstr(werr)));
                } else {
                        DEBUG(5, ("reg_reletekey_recursive_trans: deleted key '%s' from '%s'\n",
                                  path, parent->key->name));

                }
        }

        return werr;
}

WERROR reg_deletekey_recursive(struct registry_key *parent,
                               const char *path)
{
        return reg_deletekey_recursive_trans(parent, path, true);
}

WERROR reg_deletesubkeys_recursive(struct registry_key *parent,
                                   const char *path)
{
        return reg_deletekey_recursive_trans(parent, path, false);
}