/*
 * $Id$
 *
 * Copyright (C) 2007 iptelorg GmbH
 *
 * This file is part of SIP-router, a free SIP server.
 *
 * SIP-router 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 2 of the License, or
 * (at your option) any later version
 *
 * SIP-router 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * History
 * -------
 *  2007-12-03	Initial version (Miklos)
 */

#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#include "../ut.h"
#include "cfg_struct.h"
#include "cfg_script.h"
#include "cfg_ctx.h"


/* linked list of all the registered cfg contexts */
static cfg_ctx_t	*cfg_ctx_list = NULL;

/* creates a new config context that is an interface to the
 * cfg variables with write permission
 */
int cfg_register_ctx(cfg_ctx_t **handle, cfg_on_declare on_declare_cb)
{
	cfg_ctx_t	*ctx;
	cfg_group_t	*group;
	str		gname;

	/* allocate memory for the new context
	Better to use shm mem, because 'changed' and 'lock'
	must be in shm mem anyway */
	ctx = (cfg_ctx_t *)shm_malloc(sizeof(cfg_ctx_t));
	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_register_ctx(): not enough shm memory\n");
		return -1;
	}
	memset(ctx, 0, sizeof(cfg_ctx_t));
	if (lock_init(&ctx->lock) == 0) {
		LOG(L_ERR, "ERROR: cfg_register_ctx(): failed to init lock\n");
		shm_free(ctx);
		return -1;
	}

	/* add the new ctx to the beginning of the list */
	ctx->next = cfg_ctx_list;
	cfg_ctx_list = ctx;

	/* let the driver know about the already registered groups
	 * The handle of the context must be set before calling the
	 * on_declare callbacks. */
	*handle = ctx;
	if (on_declare_cb) {
		ctx->on_declare_cb = on_declare_cb;

		for (	group = cfg_group;
			group;
			group = group->next
		) {
			/* dynamic groups are not ready, the callback
			will be called later when the group is fixed-up */
			if (group->dynamic != CFG_GROUP_STATIC) continue;

			gname.s = group->name;
			gname.len = group->name_len;
			on_declare_cb(&gname, group->mapping->def);
		}
	}

	return 0;
}

/* free the memory allocated for the contexts */
void cfg_ctx_destroy(void)
{
	cfg_ctx_t	*ctx, *ctx2;

	for (	ctx = cfg_ctx_list;
		ctx;
		ctx = ctx2
	) {
		ctx2 = ctx->next;
		shm_free(ctx);
	}
	cfg_ctx_list = NULL;
}

/* notify the drivers about the new config definition */
void cfg_notify_drivers(char *group_name, int group_name_len, cfg_def_t *def)
{
	cfg_ctx_t	*ctx;
	str		gname;

	gname.s = group_name;
	gname.len = group_name_len;

	for (	ctx = cfg_ctx_list;
		ctx;
		ctx = ctx->next
	)
		if (ctx->on_declare_cb)
			ctx->on_declare_cb(&gname, def);
}

/* placeholder for a temporary string */
static char	*temp_string = NULL;

/* convert the value to the requested type */
int convert_val(unsigned int val_type, void *val,
			unsigned int var_type, void **new_val)
{
	static str	s;
	char		*end;
	int		i;
	static char	buf[INT2STR_MAX_LEN];

	/* we have to convert from val_type to var_type */
	switch (CFG_INPUT_MASK(var_type)) {
	case CFG_INPUT_INT:
		if (val_type == CFG_VAR_INT) {
			*new_val = val;
			break;

		} else if (val_type == CFG_VAR_STRING) {
			if (!val || (((char *)val)[0] == '\0')) {
				LOG(L_ERR, "ERROR: convert_val(): "
					"cannot convert NULL string value to integer\n");
				return -1;
			}
			*new_val = (void *)(long)strtol((char *)val, &end, 10);
			if (*end != '\0') {
				LOG(L_ERR, "ERROR: convert_val(): "
					"cannot convert string to integer '%s'\n",
					(char *)val);
				return -1;
			}
			break;

		} else if (val_type == CFG_VAR_STR) {
			if (!((str *)val)->len || !((str *)val)->s) {
				LOG(L_ERR, "ERROR: convert_val(): "
					"cannot convert NULL str value to integer\n");
				return -1;
			}
			if (str2sint((str *)val, &i)) {
				LOG(L_ERR, "ERROR: convert_val(): "
					"cannot convert string to integer '%.*s'\n",
					((str *)val)->len, ((str *)val)->s);
				return -1;
			}
			*new_val = (void *)(long)i;
			break;
		}
		goto error;

	case CFG_INPUT_STRING:
		if (val_type == CFG_VAR_INT) {
			buf[snprintf(buf, sizeof(buf)-1, "%ld", (long)val)] = '\0';
			*new_val = buf;
			break;

		} else if (val_type == CFG_VAR_STRING) {
			*new_val = val;
			break;

		} else if (val_type == CFG_VAR_STR) {
			if (!((str *)val)->s) {
				*new_val = NULL;
				break;
			}
			/* the value may not be zero-terminated, thus,
			a new variable has to be allocated with larger memory space */
			if (temp_string) pkg_free(temp_string);
			temp_string = (char *)pkg_malloc(sizeof(char) * (((str *)val)->len + 1));
			if (!temp_string) {
				LOG(L_ERR, "ERROR: convert_val(): not enough memory\n");
				return -1;
			}
			memcpy(temp_string, ((str *)val)->s, ((str *)val)->len);
			temp_string[((str *)val)->len] = '\0';
			*new_val = (void *)temp_string;
			break;

		}
		goto error;

	case CFG_INPUT_STR:
		if (val_type == CFG_VAR_INT) {
			s.len = snprintf(buf, sizeof(buf)-1, "%ld", (long)val);
			buf[s.len] = '\0';
			s.s = buf;
			*new_val = (void *)&s;
			break;

		} else if (val_type == CFG_VAR_STRING) {
			s.s = (char *)val;
			s.len = (s.s) ? strlen(s.s) : 0;
			*new_val = (void *)&s;
			break;

		} else if (val_type == CFG_VAR_STR) {
			*new_val = val;
			break;			
		}
		goto error;
	}

	return 0;

error:
	LOG(L_ERR, "ERROR: convert_val(): got a value with type %u, but expected %u\n",
			val_type, CFG_INPUT_MASK(var_type));
	return -1;
}

void convert_val_cleanup(void)
{
	if (temp_string) {
		pkg_free(temp_string);
		temp_string = NULL;
	}
}

/* returns the size of the variable */
static int cfg_var_size(cfg_mapping_t *var)
{
	switch (CFG_VAR_TYPE(var)) {

	case CFG_VAR_INT:
		return sizeof(int);

	case CFG_VAR_STRING:
		return sizeof(char *);

	case CFG_VAR_STR:
		return sizeof(str);

	case CFG_VAR_POINTER:
		return sizeof(void *);

	default:
		LOG(L_CRIT, "BUG: cfg_var_size(): unknown type: %u\n",
			CFG_VAR_TYPE(var));
		return 0;
	}
}

/* Update the varibales of the array within the meta structure
 * with the new default value.
 * The array is cloned before a change if clone is set to 1.
 */
static int cfg_update_defaults(cfg_group_meta_t	*meta,
				cfg_group_t *group, cfg_mapping_t *var, char *new_val,
				int clone)
{
	int	i, clone_done=0;
	cfg_group_inst_t *array, *ginst;

	if (!(array = meta->array))
		return 0;
	for (i = 0; i < meta->num; i++) {
		ginst = (cfg_group_inst_t *)((char *)array
			+ (sizeof(cfg_group_inst_t) + group->size - 1) * i);

		if (!CFG_VAR_TEST(ginst, var)) {
			/* The variable uses the default value, it needs to be rewritten. */
			if (clone && !clone_done) {
				/* The array needs to be cloned before the modification */
				if (!(array = cfg_clone_array(meta, group)))
					return -1;
				ginst = (cfg_group_inst_t *)translate_pointer((char *)array,
								(char *)meta->array,
								(char *)ginst);
				/* re-link the array to the meta-data */
				meta->array = array;
				clone_done = 1;
			}
			memcpy(ginst->vars + var->offset, new_val, cfg_var_size(var)); 
		}
	}
	return 0;
}

/* sets the value of a variable without the need of commit
 *
 * return value:
 *   0: success
 *  -1: error
 *   1: variable has not been found
 */
int cfg_set_now(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name,
			void *val, unsigned int val_type)
{
	int		i;
	cfg_group_t	*group;
	cfg_mapping_t	*var;
	void		*p, *v;
	cfg_block_t	*block = NULL;
	str		s, s2;
	char		*old_string = NULL;
	void		**replaced = NULL;
	cfg_child_cb_t	*child_cb = NULL;
	cfg_group_inst_t	*group_inst = NULL, *new_array = NULL;
	unsigned char		*var_block;

	/* verify the context even if we do not need it now
	to make sure that a cfg driver has called the function
	(very very weak security) */
	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_set_now(): context is undefined\n");
		return -1;
	}

	if ((val_type == CFG_VAR_UNSET) && !group_id) {
		LOG(L_ERR, "ERROR: cfg_set_now(): Only group instance values can be deleted\n");
		return -1;
	}

	if (group_id && !cfg_shmized) {
		/* The config group has not been shmized yet,
		but an additional instance of a variable needs to be added to the group.
		Add this instance to the linked list of variables, they
		will be fixed later. */
		return new_add_var(group_name, *group_id, var_name,
				val, val_type);
	}

	/* look-up the group and the variable */
	if (cfg_lookup_var(group_name, var_name, &group, &var)) {
		if (!cfg_shmized) {
			/* The group may be dynamic which is not yet ready
			 * before forking */
			if ((group = cfg_lookup_group(group_name->s, group_name->len))
				&& (group->dynamic == CFG_GROUP_DYNAMIC)
			)
				return cfg_set_script_var(group, var_name, val, val_type);
		}
		return 1;
	}
		
	/* check whether the variable is read-only */
	if (var->def->type & CFG_READONLY) {
		LOG(L_ERR, "ERROR: cfg_set_now(): variable is read-only\n");
		goto error0;
	}

	/* The additional variable instances having per-child process callback
	 * with CFG_CB_ONLY_ONCE flag cannot be rewritten.
	 * The reason is that such variables typically set global parameters
	 * as opposed to per-process variables. Hence, it is not possible to set
	 * the group handle temporary to another block, and then reset it back later. */
	if (group_id
		&& var->def->on_set_child_cb
		&& var->def->type & CFG_CB_ONLY_ONCE
	) {
		LOG(L_ERR, "ERROR: cfg_set_now(): This variable does not support muliple values.\n");
		goto error0;
	}

	/* check whether we have to convert the type */
	if ((val_type != CFG_VAR_UNSET)
		&& convert_val(val_type, val, CFG_INPUT_TYPE(var), &v)
	)
		goto error0;
	
	if ((val_type != CFG_VAR_UNSET)
	&& (CFG_INPUT_TYPE(var) == CFG_INPUT_INT) 
	&& (var->def->min || var->def->max)) {
		/* perform a simple min-max check for integers */
		if (((int)(long)v < var->def->min)
		|| ((int)(long)v > var->def->max)) {
			LOG(L_ERR, "ERROR: cfg_set_now(): integer value is out of range\n");
			goto error0;
		}
	}

	if ((val_type != CFG_VAR_UNSET)
		&& var->def->on_change_cb
	) {
		/* Call the fixup function.
		There is no need to set a temporary cfg handle,
		becaue a single variable is changed */
		if (!group_id) {
			var_block = *(group->handle);
		} else {
			if (!cfg_local) {
				LOG(L_ERR, "ERROR: cfg_set_now(): Local configuration is missing\n");
				goto error0;
			}
			group_inst = cfg_find_group(CFG_GROUP_META(cfg_local, group),
							group->size,
							*group_id);
			if (!group_inst) {
				LOG(L_ERR, "ERROR: cfg_set_now(): local group instance %.*s[%u] is not found\n",
					group_name->len, group_name->s, *group_id);
				goto error0;
			}
			var_block = group_inst->vars;
		}

		if (var->def->on_change_cb(var_block,
						group_name,
						var_name,
						&v) < 0) {
			LOG(L_ERR, "ERROR: cfg_set_now(): fixup failed\n");
			goto error0;
		}

	}

	/* Set the per-child process callback only if the default value is changed.
	 * The callback of other instances will be called when the config is
	 * switched to that instance. */
	if (!group_id && var->def->on_set_child_cb) {
		/* get the name of the variable from the internal struct,
		because var_name may be freed before the callback needs it */
		s.s = group->name;
		s.len = group->name_len;
		s2.s = var->def->name;
		s2.len = var->name_len;
		child_cb = cfg_child_cb_new(&s, &s2,
					var->def->on_set_child_cb,
					var->def->type);
		if (!child_cb) {
			LOG(L_ERR, "ERROR: cfg_set_now(): not enough shm memory\n");
			goto error0;
		}
	}

	if (cfg_shmized) {
		/* make sure that nobody else replaces the global config
		while the new one is prepared */
		CFG_WRITER_LOCK();

		if (group_id) {
			group_inst = cfg_find_group(CFG_GROUP_META(*cfg_global, group),
							group->size,
							*group_id);
			if (!group_inst) {
				LOG(L_ERR, "ERROR: cfg_set_now(): global group instance %.*s[%u] is not found\n",
					group_name->len, group_name->s, *group_id);
				goto error;
			}
			if ((val_type == CFG_VAR_UNSET) && !CFG_VAR_TEST(group_inst, var)) {
				/* nothing to do, the variable is not set in the group instance */
				CFG_WRITER_UNLOCK();
				LOG(L_DBG, "DEBUG: cfg_set_now(): The variable is not set\n");
				return 0;
			}
			var_block = group_inst->vars;
		} else {
			group_inst = NULL;
			var_block = CFG_GROUP_DATA(*cfg_global, group);
		}

		if (var->def->type & CFG_ATOMIC) {
			/* atomic change is allowed, we can rewrite the value
			directly in the global config */
			p = var_block + var->offset;

		} else {
			/* clone the memory block, and prepare the modification */
			if (!(block = cfg_clone_global())) goto error;

			if (group_inst) {
				/* The additional array of the group needs to be also cloned.
				 * When any of the variables within this array is changed, then
				 * the complete config block and this array is replaced. */
				if (!(new_array = cfg_clone_array(CFG_GROUP_META(*cfg_global, group), group)))
					goto error;
				group_inst = (cfg_group_inst_t *)translate_pointer((char *)new_array,
					(char *)CFG_GROUP_META(*cfg_global, group)->array,
					(char *)group_inst);
				var_block = group_inst->vars;
				CFG_GROUP_META(block, group)->array = new_array;
			} else {
				/* The additional array may need to be replaced depending
				 * on whether or not there is any variable in the array set
				 * to the default value which is changed now. If this is the case,
				 * then the array will be replaced later when the variables are
				 * updated.
				 */
				var_block = CFG_GROUP_DATA(block, group);
			}
			p = var_block + var->offset;
		}
	} else {
		/* we are allowed to rewrite the value on-the-fly
		The handle either points to group->vars, or to the
		shared memory block (dynamic group) */
		p = *(group->handle) + var->offset;
	}

	if (val_type != CFG_VAR_UNSET) {
		/* set the new value */
		switch (CFG_VAR_TYPE(var)) {
		case CFG_VAR_INT:
			*(int *)p = (int)(long)v;
			break;

		case CFG_VAR_STRING:
			/* clone the string to shm mem */
			s.s = v;
			s.len = (s.s) ? strlen(s.s) : 0;
			if (cfg_clone_str(&s, &s)) goto error;
			old_string = *(char **)p;
			*(char **)p = s.s;
			break;

		case CFG_VAR_STR:
			/* clone the string to shm mem */
			s = *(str *)v;
			if (cfg_clone_str(&s, &s)) goto error;
			old_string = *(char **)p;
			memcpy(p, &s, sizeof(str));
			break;

		case CFG_VAR_POINTER:
			*(void **)p = v;
			break;

		}
		if (group_inst && !CFG_VAR_TEST_AND_SET(group_inst, var))
			old_string = NULL; /* the string is the same as the default one,
						it cannot be freed */
	} else {
		/* copy the default value to the group instance */
		if ((CFG_VAR_TYPE(var) == CFG_VAR_STRING)
		|| (CFG_VAR_TYPE(var) == CFG_VAR_STR))
			old_string = *(char **)p;
		memcpy(p, CFG_GROUP_DATA(*cfg_global, group) + var->offset, cfg_var_size(var)); 

		CFG_VAR_TEST_AND_RESET(group_inst, var);
	}

	if (cfg_shmized) {
		if (!group_inst) {
			/* the default value is changed, the copies of this value
			need to be also updated */
			if (cfg_update_defaults(CFG_GROUP_META(block ? block : *cfg_global, group),
						group, var, p,
						block ? 1 : 0) /* clone if needed */
			)
				goto error;
			if (block && (CFG_GROUP_META(block, group)->array != CFG_GROUP_META(*cfg_global, group)->array))
				new_array = CFG_GROUP_META(block, group)->array;
		}

		if (old_string || new_array) {
			/* prepare the array of the replaced strings,
			and replaced group instances,
			they will be freed when the old block is freed */
			replaced = (void **)shm_malloc(sizeof(void *)
					* ((old_string?1:0) + (new_array?1:0) + 1));
			if (!replaced) {
				LOG(L_ERR, "ERROR: cfg_set_now(): not enough shm memory\n");
				goto error;
			}
			i = 0;
			if (old_string) {
				replaced[i] = old_string;
				i++;
			}
			if (new_array) {	
				replaced[i] = CFG_GROUP_META(*cfg_global, group)->array;
				i++;
			}
			replaced[i] = NULL;
		}
		/* replace the global config with the new one */
		if (block) cfg_install_global(block, replaced, child_cb, child_cb);
		CFG_WRITER_UNLOCK();
	} else {
		/* cfg_set() may be called more than once before forking */
		if (old_string && (var->flag & cfg_var_shmized))
			shm_free(old_string);

		/* flag the variable because there is no need
		to shmize it again */
		var->flag |= cfg_var_shmized;

		/* the global config does not have to be replaced,
		but the child callback has to be installed, otherwise the
		child processes will miss the change */
		if (child_cb)
			cfg_install_child_cb(child_cb, child_cb);
	}

	if (val_type == CFG_VAR_INT)
		LOG(L_INFO, "INFO: cfg_set_now(): %.*s.%.*s "
			"has been changed to %d\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s,
			(int)(long)val);

	else if (val_type == CFG_VAR_STRING)
		LOG(L_INFO, "INFO: cfg_set_now(): %.*s.%.*s "
			"has been changed to \"%s\"\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s,
			(char *)val);

	else if (val_type == CFG_VAR_STR)
		LOG(L_INFO, "INFO: cfg_set_now(): %.*s.%.*s "
			"has been changed to \"%.*s\"\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s,
			((str *)val)->len, ((str *)val)->s);

	else if (val_type == CFG_VAR_UNSET)
		LOG(L_INFO, "INFO: cfg_set_now(): %.*s.%.*s "
			"has been deleted\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s);

	else
		LOG(L_INFO, "INFO: cfg_set_now(): %.*s.%.*s "
			"has been changed\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s);

	if (group_id)
		LOG(L_INFO, "INFO: cfg_set_now(): group id = %u\n",
			*group_id);

	convert_val_cleanup();
	return 0;

error:
	if (cfg_shmized) CFG_WRITER_UNLOCK();
	if (block) cfg_block_free(block);
	if (new_array) shm_free(new_array);
	if (child_cb) cfg_child_cb_free_list(child_cb);
	if (replaced) shm_free(replaced);

error0:
	LOG(L_ERR, "ERROR: cfg_set_now(): failed to set the variable: %.*s.%.*s\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s);


	convert_val_cleanup();
	return -1;
}

/* wrapper function for cfg_set_now */
int cfg_set_now_int(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name,
			int val)
{
	return cfg_set_now(ctx, group_name, group_id, var_name,
				(void *)(long)val, CFG_VAR_INT);
}

/* wrapper function for cfg_set_now */
int cfg_set_now_string(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name,
			char *val)
{
	return cfg_set_now(ctx, group_name, group_id, var_name,
				(void *)val, CFG_VAR_STRING);
}

/* wrapper function for cfg_set_now */
int cfg_set_now_str(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name,
			str *val)
{
	return cfg_set_now(ctx, group_name, group_id, var_name,
				(void *)val, CFG_VAR_STR);
}

/* Delete a variable from the group instance.
 * wrapper function for cfg_set_now */
int cfg_del_now(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name)
{
	return cfg_set_now(ctx, group_name, group_id, var_name,
				NULL, CFG_VAR_UNSET);
}

/* sets the value of a variable but does not commit the change
 *
 * return value:
 *   0: success
 *  -1: error
 *   1: variable has not been found
 */
int cfg_set_delayed(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name,
			void *val, unsigned int val_type)
{
	cfg_group_t	*group;
	cfg_mapping_t	*var;
	void		*v;
	unsigned char	*temp_handle;
	int		temp_handle_created;
	cfg_changed_var_t	*changed = NULL, **changed_p;
	int		size;
	str		s;
	cfg_group_inst_t	*group_inst = NULL;
	unsigned char		*var_block;

	if (!cfg_shmized)
		/* the cfg has not been shmized yet, there is no
		point in registering the change and committing it later */
		return cfg_set_now(ctx, group_name, group_id, var_name,
					val, val_type);

	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_set_delayed(): context is undefined\n");
		return -1;
	}

	if ((val_type == CFG_VAR_UNSET) && !group_id) {
		LOG(L_ERR, "ERROR: cfg_set_delayed(): Only group instance values can be deleted\n");
		return -1;
	}

	/* look-up the group and the variable */
	if (cfg_lookup_var(group_name, var_name, &group, &var))
		return 1;

	/* check whether the variable is read-only */
	if (var->def->type & CFG_READONLY) {
		LOG(L_ERR, "ERROR: cfg_set_delayed(): variable is read-only\n");
		goto error0;
	}

	/* The additional variable instances having per-child process callback
	 * with CFG_CB_ONLY_ONCE flag cannot be rewritten.
	 * The reason is that such variables typically set global parameters
	 * as opposed to per-process variables. Hence, it is not possible to set
	 * the group handle temporary to another block, and then reset it back later. */
	if (group_id
		&& var->def->on_set_child_cb
		&& var->def->type & CFG_CB_ONLY_ONCE
	) {
		LOG(L_ERR, "ERROR: cfg_set_delayed(): This variable does not support muliple values.\n");
		goto error0;
	}

	/* check whether we have to convert the type */
	if ((val_type != CFG_VAR_UNSET)
		&& convert_val(val_type, val, CFG_INPUT_TYPE(var), &v)
	)
		goto error0;

	if ((val_type != CFG_VAR_UNSET)
	&& (CFG_INPUT_TYPE(var) == CFG_INPUT_INT) 
	&& (var->def->min || var->def->max)) {
		/* perform a simple min-max check for integers */
		if (((int)(long)v < var->def->min)
		|| ((int)(long)v > var->def->max)) {
			LOG(L_ERR, "ERROR: cfg_set_delayed(): integer value is out of range\n");
			goto error0;
		}
	}

	/* the ctx must be locked while reading and writing
	the list of changed variables */
	CFG_CTX_LOCK(ctx);

	if ((val_type != CFG_VAR_UNSET) && var->def->on_change_cb) {
		/* The fixup function must see also the
		not yet committed values, so a temporary handle
		must be prepared that points to the new config.
		Only the values within the group are applied,
		other modifications are not visible to the callback.
		The local config is the base. */
		if (!group_id) {
			var_block = *(group->handle);
		} else {
			if (!cfg_local) {
				LOG(L_ERR, "ERROR: cfg_set_delayed(): Local configuration is missing\n");
				goto error;
			}
			group_inst = cfg_find_group(CFG_GROUP_META(cfg_local, group),
							group->size,
							*group_id);
			if (!group_inst) {
				LOG(L_ERR, "ERROR: cfg_set_delayed(): local group instance %.*s[%u] is not found\n",
					group_name->len, group_name->s, *group_id);
				goto error;
			}
			var_block = group_inst->vars;
		}

		if (ctx->changed_first) {
			temp_handle = (unsigned char *)pkg_malloc(group->size);
			if (!temp_handle) {
				LOG(L_ERR, "ERROR: cfg_set_delayed(): "
					"not enough memory\n");
				goto error;
			}
			temp_handle_created = 1;
			memcpy(temp_handle, var_block, group->size);

			/* apply the changes */
			for (	changed = ctx->changed_first;
				changed;
				changed = changed->next
			) {
				if (changed->group != group)
					continue;
				if ((!group_id && !changed->group_id_set) /* default values */
					|| (group_id && !changed->group_id_set
						&& !CFG_VAR_TEST(group_inst, changed->var))
							/* default value is changed which affects the group_instance */
					|| (group_id && changed->group_id_set
						&& (*group_id == changed->group_id))
							/* change within the group instance */
				)
					memcpy(	temp_handle + changed->var->offset,
						changed->new_val.vraw,
						cfg_var_size(changed->var));
			}
		} else {
			/* there is not any change */
			temp_handle = var_block;
			temp_handle_created = 0;
		}
			
		if (var->def->on_change_cb(temp_handle,
						group_name,
						var_name,
						&v) < 0) {
			LOG(L_ERR, "ERROR: cfg_set_delayed(): fixup failed\n");
			if (temp_handle_created) pkg_free(temp_handle);
			goto error;
		}
		if (temp_handle_created) pkg_free(temp_handle);

	}

	/* everything went ok, we can add the new value to the list */
	size = sizeof(cfg_changed_var_t)
		- sizeof(((cfg_changed_var_t*)0)->new_val)
		+ ((val_type != CFG_VAR_UNSET) ? cfg_var_size(var) : 0);
	changed = (cfg_changed_var_t *)shm_malloc(size);
	if (!changed) {
		LOG(L_ERR, "ERROR: cfg_set_delayed(): not enough shm memory\n");
		goto error;
	}
	memset(changed, 0, size);
	changed->group = group;
	changed->var = var;
	if (group_id) {
		changed->group_id = *group_id;
		changed->group_id_set = 1;
	}

	if (val_type != CFG_VAR_UNSET) {
		switch (CFG_VAR_TYPE(var)) {

		case CFG_VAR_INT:
			changed->new_val.vint = (int)(long)v;
			break;

		case CFG_VAR_STRING:
			/* clone the string to shm mem */
			s.s = v;
			s.len = (s.s) ? strlen(s.s) : 0;
			if (cfg_clone_str(&s, &s)) goto error;
			changed->new_val.vp = s.s;
			break;

		case CFG_VAR_STR:
			/* clone the string to shm mem */
			s = *(str *)v;
			if (cfg_clone_str(&s, &s)) goto error;
			changed->new_val.vstr=s;
			break;

		case CFG_VAR_POINTER:
			changed->new_val.vp=v;
			break;

		}
	} else {
		changed->del_value = 1;
	}

	/* Order the changes by group + group_id + original order.
	 * Hence, the list is still kept in order within the group.
	 * The changes can be committed faster this way, the group instances
	 * do not have to be looked-up for each and every variable. */
	/* Check whether there is any variable in the list which
	belongs to the same group */
	for (	changed_p = &ctx->changed_first;
		*changed_p && ((*changed_p)->group != changed->group);
		changed_p = &(*changed_p)->next);
	/* try to find the group instance, and move changed_p to the end of
	the instance. */
	for (	;
		*changed_p
			&& ((*changed_p)->group == changed->group)
			&& (!(*changed_p)->group_id_set
				|| ((*changed_p)->group_id_set && changed->group_id_set
					&& ((*changed_p)->group_id <= changed->group_id)));
		changed_p = &(*changed_p)->next);
	/* Add the new variable before *changed_p */
	changed->next = *changed_p;
	*changed_p = changed;

	CFG_CTX_UNLOCK(ctx);

	if (val_type == CFG_VAR_INT)
		LOG(L_INFO, "INFO: cfg_set_delayed(): %.*s.%.*s "
			"is going to be changed to %d "
			"[context=%p]\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s,
			(int)(long)val,
			ctx);

	else if (val_type == CFG_VAR_STRING)
		LOG(L_INFO, "INFO: cfg_set_delayed(): %.*s.%.*s "
			"is going to be changed to \"%s\" "
			"[context=%p]\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s,
			(char *)val,
			ctx);

	else if (val_type == CFG_VAR_STR)
		LOG(L_INFO, "INFO: cfg_set_delayed(): %.*s.%.*s "
			"is going to be changed to \"%.*s\" "
			"[context=%p]\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s,
			((str *)val)->len, ((str *)val)->s,
			ctx);

	else if (val_type == CFG_VAR_UNSET)
		LOG(L_INFO, "INFO: cfg_set_delayed(): %.*s.%.*s "
			"is going to be deleted "
			"[context=%p]\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s,
			ctx);

	else
		LOG(L_INFO, "INFO: cfg_set_delayed(): %.*s.%.*s "
			"is going to be changed "
			"[context=%p]\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s,
			ctx);

	if (group_id)
		LOG(L_INFO, "INFO: cfg_set_delayed(): group id = %u "
			"[context=%p]\n",
			*group_id,
			ctx);

	convert_val_cleanup();
	return 0;

error:
	CFG_CTX_UNLOCK(ctx);
	if (changed) shm_free(changed);
error0:
	LOG(L_ERR, "ERROR: cfg_set_delayed(): failed to set the variable: %.*s.%.*s\n",
			group_name->len, group_name->s,
			var_name->len, var_name->s);

	convert_val_cleanup();
	return -1;
}

/* wrapper function for cfg_set_delayed */
int cfg_set_delayed_int(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name,
				int val)
{
	return cfg_set_delayed(ctx, group_name, group_id, var_name,
				(void *)(long)val, CFG_VAR_INT);
}

/* wrapper function for cfg_set_delayed */
int cfg_set_delayed_string(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name,
				char *val)
{
	return cfg_set_delayed(ctx, group_name, group_id, var_name,
				(void *)val, CFG_VAR_STRING);
}

/* wrapper function for cfg_set_delayed */
int cfg_set_delayed_str(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name,
				str *val)
{
	return cfg_set_delayed(ctx, group_name, group_id, var_name,
				(void *)val, CFG_VAR_STR);
}

/* Delete a variable from the group instance.
 * wrapper function for cfg_set_delayed */
int cfg_del_delayed(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name)
{
	return cfg_set_delayed(ctx, group_name, group_id, var_name,
				NULL, CFG_VAR_UNSET);
}

/* commits the previously prepared changes within the context */
int cfg_commit(cfg_ctx_t *ctx)
{
	int	replaced_num = 0;
	cfg_changed_var_t	*changed, *changed2;
	cfg_block_t	*block = NULL;
	void	**replaced = NULL;
	cfg_child_cb_t	*child_cb;
	cfg_child_cb_t	*child_cb_first = NULL;
	cfg_child_cb_t	*child_cb_last = NULL;
	int	size;
	void	*p;
	str	s, s2;
	cfg_group_t	*group;
	cfg_group_inst_t	*group_inst = NULL;

	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_commit(): context is undefined\n");
		return -1;
	}

	if (!cfg_shmized) return 0; /* nothing to do */

	/* the ctx must be locked while reading and writing
	the list of changed variables */
	CFG_CTX_LOCK(ctx);

	/* is there any change? */
	if (!ctx->changed_first) goto done;

	/* Count the number of replaced strings,
	and replaced group arrays.
	Prepare the linked list of per-child process
	callbacks, that will be added to the global list. */
	for (	changed = ctx->changed_first, group = NULL;
		changed;
		changed = changed->next
	) {
		/* Each string/str potentially causes an old string to be freed
		 * unless the variable of an additional group instance is set
		 * which uses the default value. This case cannot be determined
		 * without locking *cfg_global, hence, it is better to count these
		 * strings as well even though the slot might not be used later. */
		if ((CFG_VAR_TYPE(changed->var) == CFG_VAR_STRING)
		|| (CFG_VAR_TYPE(changed->var) == CFG_VAR_STR))
			replaced_num++;

		/* See the above comments for strings */
		if (group != changed->group) {
			replaced_num++;
			group = changed->group;
		}

		if (!changed->group_id_set && changed->var->def->on_set_child_cb) {
			s.s = changed->group->name;
			s.len = changed->group->name_len;
			s2.s = changed->var->def->name;
			s2.len = changed->var->name_len;
			child_cb = cfg_child_cb_new(&s, &s2,
					changed->var->def->on_set_child_cb,
					changed->var->def->type);
			if (!child_cb) goto error0;

			if (child_cb_last)
				child_cb_last->next = child_cb;
			else
				child_cb_first = child_cb;
			child_cb_last = child_cb;
		}
	}

	if (replaced_num) {
		/* allocate memory for the replaced string array */
		size = sizeof(void *)*(replaced_num + 1);
		replaced = (void **)shm_malloc(size);
		if (!replaced) {
			LOG(L_ERR, "ERROR: cfg_commit(): not enough shm memory\n");
			goto error0;
		}
		memset(replaced, 0 , size);
	}

	/* make sure that nobody else replaces the global config
	while the new one is prepared */
	CFG_WRITER_LOCK();

	/* clone the memory block, and prepare the modification */
	if (!(block = cfg_clone_global()))
		goto error;

	/* Apply the modifications to the buffer.
	Note that the cycle relies on the order of the groups and group instances, i.e.
	the order is group + group_id + order of commits. */
	replaced_num = 0;
	for (	changed = ctx->changed_first, group = NULL; /* group points to the
							last group array that has been cloned */
		changed;
		changed = changed->next
	) {
		if (!changed->group_id_set) {
			p = CFG_GROUP_DATA(block, changed->group)
				+ changed->var->offset;
			group_inst = NULL; /* force the look-up of the next group_inst */
		} else {
			if (group != changed->group) {
				/* The group array has not been cloned yet. */
				group = changed->group;
				if (!(CFG_GROUP_META(block, group)->array = 
					cfg_clone_array(CFG_GROUP_META(*cfg_global, group), group))
				) {
					LOG(L_ERR, "ERROR: cfg_commit(): group array cannot be cloned for %.*s[%u]\n",
						group->name_len, group->name, changed->group_id);
					goto error;
				}

				replaced[replaced_num] = CFG_GROUP_META(*cfg_global, group)->array;
				replaced_num++;

				group_inst = NULL; /* fore the look-up of group_inst */
			}
			if (!group_inst || (group_inst->id != changed->group_id)) {
				group_inst = cfg_find_group(CFG_GROUP_META(block, group),
								group->size,
								changed->group_id);
			}
			if (!group_inst) {
				LOG(L_ERR, "ERROR: cfg_commit(): global group instance %.*s[%u] is not found\n",
					group->name_len, group->name, changed->group_id);
				goto error;
			}
			p = group_inst->vars + changed->var->offset;
		}

		if (((changed->group_id_set && !changed->del_value && CFG_VAR_TEST_AND_SET(group_inst, changed->var))
			|| (changed->group_id_set && changed->del_value && CFG_VAR_TEST_AND_RESET(group_inst, changed->var))
			|| !changed->group_id_set)
		&& ((CFG_VAR_TYPE(changed->var) == CFG_VAR_STRING)
			|| (CFG_VAR_TYPE(changed->var) == CFG_VAR_STR))
		) {
			replaced[replaced_num] = *(char **)p;
			if (replaced[replaced_num])
				replaced_num++;
			/* else do not increase replaced_num, because
			the cfg_block_free() will stop at the first
			NULL value */
		}

		if (!changed->del_value)
			memcpy(	p,
				changed->new_val.vraw,
				cfg_var_size(changed->var));
		else
			memcpy(	p,
				CFG_GROUP_DATA(block, changed->group) + changed->var->offset,
				cfg_var_size(changed->var));


		if (!changed->group_id_set) {
			/* the default value is changed, the copies of this value
			need to be also updated */
			if (cfg_update_defaults(CFG_GROUP_META(block, changed->group),
						changed->group, changed->var, p,
						(group != changed->group)) /* clone if the array
									has not been cloned yet */
                        )
                                goto error;
                        if ((group != changed->group)
				&& (CFG_GROUP_META(block, changed->group)->array != CFG_GROUP_META(*cfg_global, changed->group)->array)
			) {
				/* The array has been cloned */
				group = changed->group;

				replaced[replaced_num] = CFG_GROUP_META(*cfg_global, group)->array;
				replaced_num++;
			}
		}
	}

	/* replace the global config with the new one */
	cfg_install_global(block, replaced, child_cb_first, child_cb_last);
	CFG_WRITER_UNLOCK();

	/* free the changed list */
	for (	changed = ctx->changed_first;
		changed;
		changed = changed2
	) {
		changed2 = changed->next;
		shm_free(changed);
	}
	ctx->changed_first = NULL;

done:
	LOG(L_INFO, "INFO: cfg_commit(): config changes have been applied "
			"[context=%p]\n",
			ctx);

	CFG_CTX_UNLOCK(ctx);
	return 0;

error:
	if (block) {
		/* clean the new block from the cloned arrays */
		for (	group = cfg_group;
			group;
			group = group->next
		)
			if (CFG_GROUP_META(block, group)->array
				&& (CFG_GROUP_META(block, group)->array != CFG_GROUP_META(*cfg_global, group)->array)
			)
				shm_free(CFG_GROUP_META(block, group)->array);
		/* the block can be freed outside of the writer lock */
	}
	CFG_WRITER_UNLOCK();
	if (block)
		shm_free(block);

error0:
	CFG_CTX_UNLOCK(ctx);

	if (child_cb_first) cfg_child_cb_free_list(child_cb_first);
	if (replaced) shm_free(replaced);

	return -1;
}

/* drops the not yet committed changes within the context */
int cfg_rollback(cfg_ctx_t *ctx)
{
	cfg_changed_var_t	*changed, *changed2;

	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_rollback(): context is undefined\n");
		return -1;
	}

	if (!cfg_shmized) return 0; /* nothing to do */

	LOG(L_INFO, "INFO: cfg_rollback(): deleting the config changes "
			"[context=%p]\n",
			ctx);

	/* the ctx must be locked while reading and writing
	the list of changed variables */
	CFG_CTX_LOCK(ctx);

	for (	changed = ctx->changed_first;
		changed;
		changed = changed2
	) {
		changed2 = changed->next;

		if (!changed->del_value
			&& ((CFG_VAR_TYPE(changed->var) == CFG_VAR_STRING)
				|| (CFG_VAR_TYPE(changed->var) == CFG_VAR_STR))
		) {
			if (changed->new_val.vp)
				shm_free(changed->new_val.vp);
		}
		shm_free(changed);
	}
	ctx->changed_first = NULL;

	CFG_CTX_UNLOCK(ctx);

	return 0;
}

/* retrieves the value of a variable
 * Return value:
 *  0 - success
 * -1 - error
 *  1 - variable exists, but it is not readable
 */
int cfg_get_by_name(cfg_ctx_t *ctx, str *group_name, unsigned int *group_id, str *var_name,
			void **val, unsigned int *val_type)
{
	cfg_group_t	*group;
	cfg_mapping_t	*var;
	void		*p;
	static str	s;	/* we need the value even
				after the function returns */
	cfg_group_inst_t	*group_inst;

	/* verify the context even if we do not need it now
	to make sure that a cfg driver has called the function
	(very very weak security) */
	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_get_by_name(): context is undefined\n");
		return -1;
	}

	/* look-up the group and the variable */
	if (cfg_lookup_var(group_name, var_name, &group, &var))
		return -1;

	if (var->def->on_change_cb) {
		/* The variable cannot be retrieved, because the fixup
		function may have changed it, and it is better to return
		an error than an incorrect value */
		return 1;
	}

	if (group_id) {
		if (!cfg_local) {
			LOG(L_ERR, "ERROR: cfg_get_by_name(): Local configuration is missing\n");
			return -1;
		}
		group_inst = cfg_find_group(CFG_GROUP_META(cfg_local, group),
						group->size,
						*group_id);
		if (!group_inst) {
			LOG(L_ERR, "ERROR: cfg_get_by_name(): local group instance %.*s[%u] is not found\n",
				group_name->len, group_name->s, *group_id);
			return -1;
		}
		p = group_inst->vars + var->offset;

	} else {
		/* use the module's handle to access the variable
		It means that the variable is read from the local config
		after forking */
		p = *(group->handle) + var->offset;
	}

	switch (CFG_VAR_TYPE(var)) {
	case CFG_VAR_INT:
		*val = (void *)(long)*(int *)p;
		break;

	case CFG_VAR_STRING:
		*val = (void *)*(char **)p;
		break;

	case CFG_VAR_STR:
		memcpy(&s, p, sizeof(str));
		*val = (void *)&s;
		break;

	case CFG_VAR_POINTER:
		*val = *(void **)p;
		break;

	}
	*val_type = CFG_VAR_TYPE(var);

	return 0;
}

/* returns the description of a variable */
int cfg_help(cfg_ctx_t *ctx, str *group_name, str *var_name,
			char **ch, unsigned int *input_type)
{
	cfg_mapping_t	*var;

	/* verify the context even if we do not need it now
	to make sure that a cfg driver has called the function
	(very very weak security) */
	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_help(): context is undefined\n");
		return -1;
	}

	/* look-up the group and the variable */
	if (cfg_lookup_var(group_name, var_name, NULL, &var))
		return -1;

	*ch = var->def->descr;
	if (input_type)
		*input_type = CFG_INPUT_TYPE(var);
	return 0;
}

/* return the group name and the cfg structure definition,
 * and moves the handle to the next group
 * Return value:
 *	0: no more group
 *	1: group exists
 */
int cfg_get_group_next(void **h,
			str *gname, cfg_def_t **def)
{
	cfg_group_t	*group;

	group = (cfg_group_t *)(*h);
	if (group == NULL) return 0;

	gname->s = group->name;
	gname->len = group->name_len;
	(*def) = group->mapping->def;

	(*h) = (void *)group->next;
	return 1;
}

/* Initialize the handle for cfg_diff_next() */
int cfg_diff_init(cfg_ctx_t *ctx,
		void **h)
{
	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_diff_init(): context is undefined\n");
		return -1;
	}

	CFG_CTX_LOCK(ctx);
	(*h) = (void *)ctx->changed_first;

	return 0;
}

/* return the pending changes that have not been
 * committed yet
 * return value:
 *	1: valid value is found
 *	0: no more changed value found
 *	-1: error occured 
 */
int cfg_diff_next(void **h,
			str *gname, unsigned int **gid, str *vname,
			void **old_val, void **new_val,
			unsigned int *val_type)
{
	cfg_changed_var_t	*changed;
	cfg_group_inst_t	*group_inst;
	union cfg_var_value	*pval_old, *pval_new;
	static str	old_s, new_s;	/* we need the value even
					after the function returns */

	changed = (cfg_changed_var_t *)(*h);
	if (changed == NULL) return 0;

	gname->s = changed->group->name;
	gname->len = changed->group->name_len;
	*gid = (changed->group_id_set ? &changed->group_id : NULL);
	vname->s = changed->var->def->name;
	vname->len = changed->var->name_len;

	/* use the module's handle to access the variable
	It means that the variable is read from the local config
	after forking */
	if (!changed->group_id_set) {
		pval_old = (union cfg_var_value*)
				(*(changed->group->handle) + changed->var->offset);
	} else {
		if (!cfg_local) {
			LOG(L_ERR, "ERROR: cfg_diff_next(): Local configuration is missing\n");
			return -1;
		}
		group_inst = cfg_find_group(CFG_GROUP_META(cfg_local, changed->group),
						changed->group->size,
						changed->group_id);
		if (!group_inst) {
			LOG(L_ERR, "ERROR: cfg_diff_next(): local group instance %.*s[%u] is not found\n",
				changed->group->name_len, changed->group->name, changed->group_id);
			return -1;
		}
		pval_old = (union cfg_var_value*)
				(group_inst->vars + changed->var->offset);
	}
	if (!changed->del_value)
		pval_new = &changed->new_val;
	else
		pval_new = (union cfg_var_value*)
				(*(changed->group->handle) + changed->var->offset);

	switch (CFG_VAR_TYPE(changed->var)) {
	case CFG_VAR_INT:
		*old_val = (void *)(long)pval_old->vint;
		*new_val = (void *)(long)pval_new->vint;
		break;

	case CFG_VAR_STRING:
		*old_val = pval_old->vp;
		*new_val = pval_new->vp;
		break;

	case CFG_VAR_STR:
		old_s=pval_old->vstr;
		*old_val = (void *)&old_s;
		new_s=pval_new->vstr;
		*new_val = (void *)&new_s;
		break;

	case CFG_VAR_POINTER:
		*old_val = pval_old->vp;
		*new_val = pval_new->vp;
		break;

	}
	*val_type = CFG_VAR_TYPE(changed->var);

	(*h) = (void *)changed->next;
	return 1;
}

/* release the handle of cfg_diff_next() */
void cfg_diff_release(cfg_ctx_t *ctx)
{
	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_diff_release(): context is undefined\n");
		return;
	}

	CFG_CTX_UNLOCK(ctx);
}

/* Add a new instance to an existing group */
int cfg_add_group_inst(cfg_ctx_t *ctx, str *group_name, unsigned int group_id)
{
	cfg_group_t	*group;
	cfg_block_t	*block = NULL;
	void		**replaced = NULL;
	cfg_group_inst_t	*new_array = NULL, *new_inst;

	/* verify the context even if we do not need it now
	to make sure that a cfg driver has called the function
	(very very weak security) */
	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_add_group_inst(): context is undefined\n");
		return -1;
	}

	if (!cfg_shmized) {
		/* Add a new variable without any value to
		the linked list of additional values. This variable
		will force a new group instance to be created. */
		return new_add_var(group_name, group_id,  NULL /* var_name */,
					NULL /* val */, 0 /* type */);
	}

	if (!(group = cfg_lookup_group(group_name->s, group_name->len))) {
		LOG(L_ERR, "ERROR: cfg_add_group_inst(): group not found\n");
		return -1;
	}

	/* make sure that nobody else replaces the global config
	while the new one is prepared */
	CFG_WRITER_LOCK();
	if (cfg_find_group(CFG_GROUP_META(*cfg_global, group),
							group->size,
							group_id)
	) {
		LOG(L_DBG, "DEBUG: cfg_add_group_inst(): the group instance already exists\n");
		CFG_WRITER_UNLOCK();
		return 0; /* not an error */
	}

	/* clone the global memory block because the additional array can be
	replaced only together with the block. */
	if (!(block = cfg_clone_global()))
		goto error;

	/* Extend the array with a new group instance */
	if (!(new_array = cfg_extend_array(CFG_GROUP_META(*cfg_global, group), group,
					group_id,
					&new_inst))
	)
		goto error;

	/* fill in the new group instance with the default data */
	memcpy(	new_inst->vars,
		CFG_GROUP_DATA(*cfg_global, group),
		group->size);

	CFG_GROUP_META(block, group)->array = new_array;
	CFG_GROUP_META(block, group)->num++;

	if (CFG_GROUP_META(*cfg_global, group)->array) {
		/* prepare the array of the replaced strings,
		and replaced group instances,
		they will be freed when the old block is freed */
		replaced = (void **)shm_malloc(sizeof(void *) * 2);
		if (!replaced) {
			LOG(L_ERR, "ERROR: cfg_add_group_inst(): not enough shm memory\n");
			goto error;
		}
		replaced[0] = CFG_GROUP_META(*cfg_global, group)->array;
		replaced[1] = NULL;
	}
	/* replace the global config with the new one */
	cfg_install_global(block, replaced, NULL, NULL);
	CFG_WRITER_UNLOCK();

	LOG(L_INFO, "INFO: cfg_add_group_inst(): "
		"group instance is added: %.*s[%u]\n",
		group_name->len, group_name->s,
		group_id);

	/* Make sure that cfg_set_*() sees the change when
	 * the function is immediately called after the group
	 * instance has been added. */
	cfg_update();

	return 0;
error:
	CFG_WRITER_UNLOCK();
	if (block) cfg_block_free(block);
	if (new_array) shm_free(new_array);
	if (replaced) shm_free(replaced);

	LOG(L_ERR, "ERROR: cfg_add_group_inst(): "
		"Failed to add the group instance: %.*s[%u]\n",
		group_name->len, group_name->s,
		group_id);

	return -1;
}

/* Delete an instance of a group */
int cfg_del_group_inst(cfg_ctx_t *ctx, str *group_name, unsigned int group_id)
{
	cfg_group_t	*group;
	cfg_block_t	*block = NULL;
	void		**replaced = NULL;
	cfg_group_inst_t	*new_array = NULL, *group_inst;
	cfg_mapping_t	*var;
	int		i, num;

	/* verify the context even if we do not need it now
	to make sure that a cfg driver has called the function
	(very very weak security) */
	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_del_group_inst(): context is undefined\n");
		return -1;
	}

	if (!cfg_shmized) {
		/* It makes no sense to delete a group instance that has not
		been created yet */
		return -1;
	}

	if (!(group = cfg_lookup_group(group_name->s, group_name->len))) {
		LOG(L_ERR, "ERROR: cfg_del_group_inst(): group not found\n");
		return -1;
	}

	/* make sure that nobody else replaces the global config
	while the new one is prepared */
	CFG_WRITER_LOCK();
	if (!(group_inst = cfg_find_group(CFG_GROUP_META(*cfg_global, group),
							group->size,
							group_id))
	) {
		LOG(L_DBG, "DEBUG: cfg_del_group_inst(): the group instance does not exist\n");
		goto error;
	}

	/* clone the global memory block because the additional array can be
	replaced only together with the block. */
	if (!(block = cfg_clone_global()))
		goto error;

	/* Remove the group instance from the array. */
	if (cfg_collapse_array(CFG_GROUP_META(*cfg_global, group), group,
					group_inst,
					&new_array)
	)
		goto error;

	CFG_GROUP_META(block, group)->array = new_array;
	CFG_GROUP_META(block, group)->num--;

	if (CFG_GROUP_META(*cfg_global, group)->array) {
		/* prepare the array of the replaced strings,
		and replaced group instances,
		they will be freed when the old block is freed */

		/* count the number of strings that has to be freed */
		num = 0;
		for (i = 0; i < group->num; i++) {
			var = &group->mapping[i];
			if (CFG_VAR_TEST(group_inst, var)
				&& ((CFG_VAR_TYPE(var) == CFG_VAR_STRING) || (CFG_VAR_TYPE(var) == CFG_VAR_STR))
				&& (*(char **)(group_inst->vars + var->offset) != NULL)
			)
				num++;
		}

		replaced = (void **)shm_malloc(sizeof(void *) * (num + 2));
		if (!replaced) {
			LOG(L_ERR, "ERROR: cfg_del_group_inst(): not enough shm memory\n");
			goto error;
		}

		if (num) {
			/* There was at least one string to free, go though the list again */
			num = 0;
			for (i = 0; i < group->num; i++) {
				var = &group->mapping[i];
				if (CFG_VAR_TEST(group_inst, var)
					&& ((CFG_VAR_TYPE(var) == CFG_VAR_STRING) || (CFG_VAR_TYPE(var) == CFG_VAR_STR))
					&& (*(char **)(group_inst->vars + var->offset) != NULL)
				) {
					replaced[num] = *(char **)(group_inst->vars + var->offset);
					num++;
				}
			}
		}

		replaced[num] = CFG_GROUP_META(*cfg_global, group)->array;
		replaced[num+1] = NULL;
	}
	/* replace the global config with the new one */
	cfg_install_global(block, replaced, NULL, NULL);
	CFG_WRITER_UNLOCK();

	LOG(L_INFO, "INFO: cfg_del_group_inst(): "
		"group instance is deleted: %.*s[%u]\n",
		group_name->len, group_name->s,
		group_id);

	/* Make sure that cfg_set_*() sees the change when
	 * the function is immediately called after the group
	 * instance has been deleted. */
	cfg_update();

	return 0;
error:
	CFG_WRITER_UNLOCK();
	if (block) cfg_block_free(block);
	if (new_array) shm_free(new_array);
	if (replaced) shm_free(replaced);

	LOG(L_ERR, "ERROR: cfg_add_group_inst(): "
		"Failed to delete the group instance: %.*s[%u]\n",
		group_name->len, group_name->s,
		group_id);

	return -1;
}

/* Check the existance of a group instance.
 * return value:
 *	1: exists
 *	0: does not exist
 */
int cfg_group_inst_exists(cfg_ctx_t *ctx, str *group_name, unsigned int group_id)
{
	cfg_group_t	*group;
	cfg_add_var_t	*add_var;
	int	found;

	/* verify the context even if we do not need it now
	to make sure that a cfg driver has called the function
	(very very weak security) */
	if (!ctx) {
		LOG(L_ERR, "ERROR: cfg_group_inst_exists(): context is undefined\n");
		return 0;
	}

	if (!(group = cfg_lookup_group(group_name->s, group_name->len))) {
		LOG(L_ERR, "ERROR: cfg_group_inst_exists(): group not found\n");
		return 0;
	}

	if (!cfg_shmized) {
		/* group instances are stored in the additional variable list
		 * before forking */
		found = 0;
		for (	add_var = group->add_var;
			add_var;
			add_var = add_var->next
		)
			if (add_var->group_id == group_id) {
				found = 1;
				break;
			}

	} else {
		/* make sure that nobody else replaces the global config meantime */
		CFG_WRITER_LOCK();
		found = (cfg_find_group(CFG_GROUP_META(*cfg_global, group),
								group->size,
								group_id)
				!= NULL);
		CFG_WRITER_UNLOCK();
	}

	return found;
}

/* Apply the changes to a group instance as long as the additional variable
 * belongs to the specified group_id. *add_var_p is moved to the next additional
 * variable, and all the consumed variables are freed.
 * This function can be used only during the cfg shmize process.
 * For internal use only!
 */
int cfg_apply_list(cfg_group_inst_t *ginst, cfg_group_t *group,
			unsigned int group_id, cfg_add_var_t **add_var_p)
{
	cfg_add_var_t	*add_var;
	cfg_mapping_t	*var;
	void		*val, *v, *p;
	str		group_name, var_name, s;
	char		*old_string;

	group_name.s = group->name;
	group_name.len = group->name_len;
	while (*add_var_p && ((*add_var_p)->group_id == group_id)) {
		add_var = *add_var_p;

		if (add_var->type == 0)
			goto done; /* Nothing needs to be changed,
				this additional variable only forces a new
				group instance to be created. */
		var_name.s = add_var->name;
		var_name.len = add_var->name_len;

		if (!(var = cfg_lookup_var2(group, add_var->name, add_var->name_len))) {
			LOG(L_ERR, "ERROR: cfg_apply_list(): Variable is not found: %.*s.%.*s\n",
				group->name_len, group->name,
				add_var->name_len, add_var->name);
			goto error;
		}

		/* check whether the variable is read-only */
		if (var->def->type & CFG_READONLY) {
			LOG(L_ERR, "ERROR: cfg_apply_list(): variable is read-only\n");
			goto error;
		}

		/* The additional variable instances having per-child process callback
		 * with CFG_CB_ONLY_ONCE flag cannot be rewritten.
		 * The reason is that such variables typically set global parameters
		 * as opposed to per-process variables. Hence, it is not possible to set
		 * the group handle temporary to another block, and then reset it back later. */
		if (var->def->on_set_child_cb
			&& var->def->type & CFG_CB_ONLY_ONCE
		) {
			LOG(L_ERR, "ERROR: cfg_apply_list(): This variable does not support muliple values.\n");
			goto error;
		}

		switch(add_var->type) {
		case CFG_VAR_INT:
			val = (void *)(long)add_var->val.i;
			break;
		case CFG_VAR_STR:
			val = (str *)&(add_var->val.s);
			break;
		case CFG_VAR_STRING:
			val = (char *)add_var->val.ch;
			break;
		default:
			LOG(L_ERR, "ERROR: cfg_apply_list(): unsupported variable type: %d\n",
				add_var->type);
			goto error;
		}
		/* check whether we have to convert the type */
		if (convert_val(add_var->type, val, CFG_INPUT_TYPE(var), &v))
			goto error;

		if ((CFG_INPUT_TYPE(var) == CFG_INPUT_INT) 
		&& (var->def->min || var->def->max)) {
			/* perform a simple min-max check for integers */
			if (((int)(long)v < var->def->min)
			|| ((int)(long)v > var->def->max)) {
				LOG(L_ERR, "ERROR: cfg_apply_list(): integer value is out of range\n");
				goto error;
			}
		}

		if (var->def->on_change_cb) {
			/* Call the fixup function.
			The handle can point to the variables of the group instance. */
			if (var->def->on_change_cb(ginst->vars,
							&group_name,
							&var_name,
							&v) < 0) {
				LOG(L_ERR, "ERROR: cfg_apply_list(): fixup failed\n");
				goto error;
			}
		}

		p = ginst->vars + var->offset;
		old_string = NULL;
		/* set the new value */
		switch (CFG_VAR_TYPE(var)) {
		case CFG_VAR_INT:
			*(int *)p = (int)(long)v;
			break;

		case CFG_VAR_STRING:
			/* clone the string to shm mem */
			s.s = v;
			s.len = (s.s) ? strlen(s.s) : 0;
			if (cfg_clone_str(&s, &s)) goto error;
			old_string = *(char **)p;
			*(char **)p = s.s;
			break;

		case CFG_VAR_STR:
			/* clone the string to shm mem */
			s = *(str *)v;
			if (cfg_clone_str(&s, &s)) goto error;
			old_string = *(char **)p;
			memcpy(p, &s, sizeof(str));
			break;

		case CFG_VAR_POINTER:
			*(void **)p = v;
			break;

		}
		if (CFG_VAR_TEST_AND_SET(ginst, var) && old_string)
			shm_free(old_string); /* the string was already in shm memory,
					it needs to be freed.
					This can happen when the same variable is set
					multiple times before forking. */

		if (add_var->type == CFG_VAR_INT)
			LOG(L_INFO, "INFO: cfg_apply_list(): %.*s[%u].%.*s "
				"has been set to %d\n",
				group_name.len, group_name.s,
				group_id,
				var_name.len, var_name.s,
				(int)(long)val);

		else if (add_var->type == CFG_VAR_STRING)
			LOG(L_INFO, "INFO: cfg_apply_list(): %.*s[%u].%.*s "
				"has been set to \"%s\"\n",
				group_name.len, group_name.s,
				group_id,
				var_name.len, var_name.s,
				(char *)val);

		else /* str type */
			LOG(L_INFO, "INFO: cfg_apply_list(): %.*s[%u].%.*s "
				"has been set to \"%.*s\"\n",
				group_name.len, group_name.s,
				group_id,
				var_name.len, var_name.s,
				((str *)val)->len, ((str *)val)->s);

		convert_val_cleanup();

done:
		*add_var_p = add_var->next;

		if ((add_var->type == CFG_VAR_STR) && add_var->val.s.s)
			pkg_free(add_var->val.s.s);
		else if ((add_var->type == CFG_VAR_STRING) && add_var->val.ch)
			pkg_free(add_var->val.ch);
		pkg_free(add_var);
	}
	return 0;

error:
	LOG(L_ERR, "ERROR: cfg_apply_list(): Failed to set the value for: %.*s[%u].%.*s\n",
		group->name_len, group->name,
		group_id,
		add_var->name_len, add_var->name);
	convert_val_cleanup();
	return -1;
}