/*
 * Copyright (c) 2024 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/** @addtogroup libsif
 * @{
 */
/**
 * @file Structured Information Format
 *
 * Structured Information Format (SIF) is an API that allows an application
 * to maintain data in a persistent repository in a format that is
 * structured (and hence extensible).
 *
 * SIF is meant to be used as the basis for the storage backend used to
 * maintain application or configuration data. SIF is *not* a (relational)
 * database (not even close). The structure of a SIF repository is quite
 * similar to an XML document that contains just tags with attributes
 * (but no text).
 */

#include <adt/list.h>
#include <adt/odict.h>
#include <ctype.h>
#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <str.h>
#include "../include/sif.h"
#include "../private/sif.h"

static errno_t sif_export_node(sif_node_t *, FILE *);
static errno_t sif_import_node(sif_node_t *, FILE *, sif_node_t **, bool *);
static sif_attr_t *sif_node_first_attr(sif_node_t *);
static sif_attr_t *sif_node_next_attr(sif_attr_t *);
static void sif_attr_delete(sif_attr_t *);
static void *sif_attr_getkey(odlink_t *);
static int sif_attr_cmp(void *, void *);

/** Determine if character can start a name.
 *
 * @param c Character
 * @return @c true iff the character can start a name
 */
static bool sif_is_name_start_char(char c)
{
	return isalpha(c) || c == '_';
}

/** Determine if character can continue a name.
 *
 * @param c Character
 * @return @c true iff the character can continue a name
 */
static bool sif_is_name_char(char c)
{
	return isalnum(c) || c == '-' || c == '.';
}

/** Create new SIF node.
 *
 * @param parent Parent node
 * @return Pointer to new node on success or @c NULL if out of memory
 */
static sif_node_t *sif_node_new(sif_node_t *parent)
{
	sif_node_t *node;

	node = calloc(1, sizeof(sif_node_t));
	if (node == NULL)
		return NULL;

	node->parent = parent;
	odict_initialize(&node->attrs, sif_attr_getkey, sif_attr_cmp);
	list_initialize(&node->children);

	return node;
}

/** Delete SIF node.
 *
 * Delete a SIF node that has been already unlinked from the tree.
 * This will also delete any attributes or child nodes.
 *
 * @param node Node
 */
static void sif_node_delete(sif_node_t *node)
{
	sif_attr_t *attr;
	sif_node_t *child;

	if (node == NULL)
		return;

	assert(!link_used(&node->lparent));

	if (node->ntype != NULL)
		free(node->ntype);

	attr = sif_node_first_attr(node);
	while (attr != NULL) {
		odict_remove(&attr->lattrs);
		sif_attr_delete(attr);
		attr = sif_node_first_attr(node);
	}

	child = sif_node_first_child(node);
	while (child != NULL) {
		list_remove(&child->lparent);
		sif_node_delete(child);
		child = sif_node_first_child(node);
	}

	free(node);
}

/** Create new SIF attribute.
 *
 * @param node Containing node
 * @return Pointer to new node on success or @c NULL if out of memory
 */
static sif_attr_t *sif_attr_new(sif_node_t *node)
{
	sif_attr_t *attr;

	attr = calloc(1, sizeof(sif_attr_t));
	if (attr == NULL)
		return NULL;

	attr->node = node;
	return attr;
}

/** Delete SIF attribute.
 *
 * Delete a SIF attribute that has been already unlinked from is node.
 *
 * @param attr Attribute
 */
static void sif_attr_delete(sif_attr_t *attr)
{
	if (attr == NULL)
		return;

	assert(!odlink_used(&attr->lattrs));

	if (attr->aname != NULL)
		free(attr->aname);
	if (attr->avalue != NULL)
		free(attr->avalue);

	free(attr);
}

/** Create SIF document.
 *
 * @param rdoc Place to store pointer to new document.
 *
 * @return EOK on success or error code
 */
errno_t sif_new(sif_doc_t **rdoc)
{
	sif_doc_t *doc;
	sif_node_t *root = NULL;
	errno_t rc;

	doc = calloc(1, sizeof(sif_doc_t));
	if (doc == NULL)
		return ENOMEM;

	root = sif_node_new(NULL);
	if (root == NULL) {
		rc = ENOMEM;
		goto error;
	}

	root->ntype = str_dup("sif");
	if (root->ntype == NULL) {
		rc = ENOMEM;
		goto error;
	}

	doc->root = root;

	*rdoc = doc;
	return EOK;
error:
	sif_node_delete(root);
	free(doc);
	return rc;
}

/** Load SIF document.
 *
 * @param fname File name
 * @param rdoc Place to store pointer to new document.
 *
 * @return EOK on success or error code
 */
errno_t sif_load(const char *fname, sif_doc_t **rdoc)
{
	sif_doc_t *doc;
	sif_node_t *root = NULL;
	errno_t rc;
	bool endtag;
	FILE *f = NULL;

	doc = calloc(1, sizeof(sif_doc_t));
	if (doc == NULL)
		return ENOMEM;

	doc->fname = str_dup(fname);
	if (doc->fname == NULL) {
		rc = ENOMEM;
		goto error;
	}

	f = fopen(fname, "r");
	if (f == NULL) {
		rc = EIO;
		goto error;
	}

	rc = sif_import_node(NULL, f, &root, &endtag);
	if (rc != EOK || endtag == true)
		goto error;

	if (str_cmp(root->ntype, "sif") != 0) {
		rc = EIO;
		goto error;
	}

	fclose(f);
	doc->root = root;
	*rdoc = doc;
	return EOK;
error:
	sif_node_delete(root);
	free(doc);
	if (f != NULL)
		fclose(f);
	return rc;
}

/** Delete SIF document.
 *
 * @param doc SIF document
 * @return EOK on success or error code
 */
void sif_delete(sif_doc_t *doc)
{
	sif_node_delete(doc->root);
	free(doc);
}

/** Return root node.
 *
 * @param doc SIF document
 */
sif_node_t *sif_get_root(sif_doc_t *doc)
{
	return doc->root;
}

/** Get first child of a node.
 *
 * @param parent Parent node
 * @return First child node or @c NULL if @a parent has no children
 */
sif_node_t *sif_node_first_child(sif_node_t *parent)
{
	link_t *link;

	link = list_first(&parent->children);
	if (link == NULL)
		return NULL;

	return list_get_instance(link, sif_node_t, lparent);
}

/** Get next child of a node.
 *
 * @param current Current node
 * @return Next child (i.e. next sibling of @a current)
 */
sif_node_t *sif_node_next_child(sif_node_t *current)
{
	link_t *link;

	link = list_next(&current->lparent, &current->parent->children);
	if (link == NULL)
		return NULL;

	return list_get_instance(link, sif_node_t, lparent);
}

/** Get node type.
 *
 * @param node SIF node
 * @return Pointer to string, valid until next modification.
 */
const char *sif_node_get_type(sif_node_t *node)
{
	return node->ntype;
}

/** Get node attribute.
 *
 * @param node SIF node
 * @param aname Attribute name
 *
 * @return Attribute value or @c NULL if attribute is not set
 */
const char *sif_node_get_attr(sif_node_t *node, const char *aname)
{
	odlink_t *link;
	sif_attr_t *attr;

	link = odict_find_eq(&node->attrs, (void *)aname, NULL);
	if (link == NULL)
		return NULL;

	attr = odict_get_instance(link, sif_attr_t, lattrs);
	return attr->avalue;
}

/** Save SIF document to file.
 * *
 * @param doc SIF document
 * @param fname File name
 * @return EOK on success or error code
 */
errno_t sif_save(sif_doc_t *doc, const char *fname)
{
	FILE *f = NULL;
	errno_t rc;

	f = fopen(fname, "w");
	if (f == NULL) {
		rc = EIO;
		goto error;
	}

	rc = sif_export_node(doc->root, f);
	if (rc != EOK)
		goto error;

	if (fflush(f) == EOF) {
		rc = EIO;
		goto error;
	}

	fclose(f);
	return EOK;
error:
	if (f != NULL)
		fclose(f);
	return rc;
}

/** Prepend new child.
 *
 * Create a new child and prepend it at the beginning of children list of
 * @a parent.
 *
 * @param parent Parent node
 * @param ctype Child type
 * @param rchild Place to store pointer to new child
 *
 * @return EOK on success or ENOMEM if out of memory
 */
errno_t sif_node_prepend_child(sif_node_t *parent, const char *ctype,
    sif_node_t **rchild)
{
	sif_node_t *child;

	child = sif_node_new(parent);
	if (child == NULL)
		return ENOMEM;

	child->ntype = str_dup(ctype);
	if (child->ntype == NULL) {
		sif_node_delete(child);
		return ENOMEM;
	}

	list_prepend(&child->lparent, &parent->children);

	*rchild = child;
	return EOK;
}

/** Append new child.
 *
 * Create a new child and append it at the end of children list of @a parent.
 *
 * @param parent Parent node
 * @param ctype Child type
 * @param rchild Place to store pointer to new child
 *
 * @return EOK on success or ENOMEM if out of memory
 */
errno_t sif_node_append_child(sif_node_t *parent, const char *ctype,
    sif_node_t **rchild)
{
	sif_node_t *child;

	child = sif_node_new(parent);
	if (child == NULL)
		return ENOMEM;

	child->ntype = str_dup(ctype);
	if (child->ntype == NULL) {
		sif_node_delete(child);
		return ENOMEM;
	}

	list_append(&child->lparent, &parent->children);

	*rchild = child;
	return EOK;
}

/** Insert new child before existing child.
 *
 * Create a new child and insert it before an existing child.
 *
 * @param sibling Sibling before which to insert
 * @param ctype Child type
 * @param rchild Place to store pointer to new child
 *
 * @return EOK on success or ENOMEM if out of memory
 */
errno_t sif_node_insert_before(sif_node_t *sibling, const char *ctype,
    sif_node_t **rchild)
{
	sif_node_t *child;

	child = sif_node_new(sibling->parent);
	if (child == NULL)
		return ENOMEM;

	child->ntype = str_dup(ctype);
	if (child->ntype == NULL) {
		sif_node_delete(child);
		return ENOMEM;
	}

	list_insert_before(&child->lparent, &sibling->lparent);

	*rchild = child;
	return EOK;
}

/** Insert new child after existing child.
 *
 * Create a new child and insert it after an existing child.
 *
 * @param sibling Sibling after which to insert
 * @param ctype Child type
 * @param rchild Place to store pointer to new child
 *
 * @return EOK on success or ENOMEM if out of memory
 */
errno_t sif_node_insert_after(sif_node_t *sibling, const char *ctype,
    sif_node_t **rchild)
{
	sif_node_t *child;

	child = sif_node_new(sibling->parent);
	if (child == NULL)
		return ENOMEM;

	child->ntype = str_dup(ctype);
	if (child->ntype == NULL) {
		sif_node_delete(child);
		return ENOMEM;
	}

	list_insert_after(&child->lparent, &sibling->lparent);

	*rchild = child;
	return EOK;
}

/** Destroy SIF node.
 *
 * @param node Node to destroy
 */
void sif_node_destroy(sif_node_t *node)
{
	list_remove(&node->lparent);
	sif_node_delete(node);
}

/** Set node attribute.
 *
 * @param node SIF node
 * @param aname Attribute name
 * @param value Attribute value
 *
 * @return EOK on success, ENOMEM if out of memory
 */
errno_t sif_node_set_attr(sif_node_t *node, const char *aname,
    const char *avalue)
{
	odlink_t *link;
	sif_attr_t *attr;
	char *cvalue;

	link = odict_find_eq(&node->attrs, (void *)aname, NULL);

	if (link != NULL) {
		attr = odict_get_instance(link, sif_attr_t, lattrs);
		cvalue = str_dup(avalue);
		if (cvalue == NULL)
			return ENOMEM;

		free(attr->avalue);
		attr->avalue = cvalue;
	} else {
		attr = sif_attr_new(node);
		if (attr == NULL)
			return ENOMEM;

		attr->aname = str_dup(aname);
		if (attr->aname == NULL) {
			sif_attr_delete(attr);
			return ENOMEM;
		}

		attr->avalue = str_dup(avalue);
		if (attr->avalue == NULL) {
			sif_attr_delete(attr);
			return ENOMEM;
		}

		odict_insert(&attr->lattrs, &node->attrs, NULL);
	}

	return EOK;
}

/** Unset node attribute.
 *
 * @param node Node
 * @param aname Attribute name
 */
void sif_node_unset_attr(sif_node_t *node, const char *aname)
{
	odlink_t *link;
	sif_attr_t *attr;

	link = odict_find_eq(&node->attrs, (void *)aname, NULL);
	if (link == NULL)
		return;

	attr = odict_get_instance(link, sif_attr_t, lattrs);
	odict_remove(link);
	sif_attr_delete(attr);
}

/** Export node name to file.
 *
 * Export node name to file.
 *
 * @param str String
 * @param f File
 * @return EOK on success, EIO on I/O error
 */
static errno_t sif_export_name(const char *str, FILE *f)
{
	if (fputs(str, f) == EOF)
		return EIO;

	return EOK;
}

/** Export string to file.
 *
 * Export string to file (the string is double-quoted and escaped).
 *
 * @param str String
 * @param f File
 * @return EOK on success, EIO on I/O error
 */
static errno_t sif_export_string(const char *str, FILE *f)
{
	const char *cp;

	if (fputc('"', f) == EOF)
		return EIO;

	cp = str;
	while (*cp != '\0') {
		if (*cp == '<') {
			if (fputs("&lt;", f) == EOF)
				return EIO;
		} else if (*cp == '"') {
			if (fputs("&quot;", f) == EOF)
				return EIO;
		} else {
			if (fputc(*cp, f) == EOF)
				return EIO;
		}

		++cp;
	}

	if (fputc('"', f) == EOF)
		return EIO;

	return EOK;
}

/** Read characters from file, make sure they match the specified sequence.
 *
 * @param f File
 * @param chars Expected sequence of characters to be read
 *
 * @return EOK on success, EIO on I/O error or mismatch
 */
static errno_t sif_get_verify_chars(FILE *f, const char *chars)
{
	const char *cp;
	char c;

	cp = chars;
	while (*cp != '\0') {
		c = fgetc(f);
		if (c != *cp)
			return EIO;
		++cp;
	}

	return EOK;
}

/** Import name from file.
 * *
 * @param f File
 * @param rstr Place to store pointer to newly allocated string
 * @return EOK on success, EIO on I/O error
 */
static errno_t sif_import_name(FILE *f, char **rstr)
{
	char *str;
	char *nstr;
	size_t str_size;
	size_t sidx;
	int c;
	errno_t rc;

	str_size = 1;
	sidx = 0;
	str = malloc(str_size + 1);
	if (str == NULL)
		return ENOMEM;

	c = fgetc(f);
	if (!sif_is_name_start_char(c)) {
		rc = EIO;
		goto error;
	}

	while (true) {
		if (sidx >= str_size) {
			str_size *= 2;
			nstr = realloc(str, str_size + 1);
			if (nstr == NULL) {
				rc = ENOMEM;
				goto error;
			}

			str = nstr;
		}

		str[sidx++] = c;

		c = fgetc(f);
		if (!sif_is_name_char(c))
			break;
	}

	ungetc(c, f);

	str[sidx] = '\0';
	*rstr = str;
	return EOK;
error:
	free(str);
	return rc;
}

/** Import string from file.
 *
 * Import string from file (the string in the file must be
 * properly quoted and escaped).
 *
 * @param f File
 * @param rstr Place to store pointer to newly allocated string
 * @return EOK on success, EIO on I/O error
 */
static errno_t sif_import_string(FILE *f, char **rstr)
{
	char *str;
	char *nstr;
	size_t str_size;
	size_t sidx;
	int c;
	errno_t rc;

	str_size = 1;
	sidx = 0;
	str = malloc(str_size + 1);
	if (str == NULL)
		return ENOMEM;

	c = fgetc(f);
	if (c != '"') {
		rc = EIO;
		goto error;
	}

	while (true) {
		c = fgetc(f);
		if (c == EOF) {
			rc = EIO;
			goto error;
		}

		if (c == '"')
			break;

		if (c == '&') {
			c = fgetc(f);
			if (c == EOF) {
				rc = EIO;
				goto error;
			}

			if (c == 'q') {
				rc = sif_get_verify_chars(f, "uot;");
				if (rc != EOK)
					goto error;
			} else if (c == 'l') {
				rc = sif_get_verify_chars(f, "t;");
				if (rc != EOK)
					goto error;
			} else {
				rc = EIO;
				goto error;
			}
		}

		if (sidx >= str_size) {
			str_size *= 2;
			nstr = realloc(str, str_size + 1);
			if (nstr == NULL) {
				rc = ENOMEM;
				goto error;
			}

			str = nstr;
		}

		str[sidx++] = c;
	}

	str[sidx] = '\0';
	*rstr = str;
	return EOK;
error:
	free(str);
	return rc;
}

/** Import SIF attribute from file.
 *
 * @param node Node under which attribute shou
 * @param f File
 * @param rattr Place to store pointer to imported SIF attribute
 * @return EOK on success, EIO on I/O error
 */
static errno_t sif_import_attr(sif_node_t *node, FILE *f, sif_attr_t **rattr)
{
	errno_t rc;
	char *aname = NULL;
	char *avalue = NULL;
	sif_attr_t *attr;
	int c;

	rc = sif_import_name(f, &aname);
	if (rc != EOK)
		goto error;

	c = fgetc(f);
	if (c != '=') {
		rc = EIO;
		goto error;
	}

	rc = sif_import_string(f, &avalue);
	if (rc != EOK)
		goto error;

	attr = sif_attr_new(node);
	if (attr == NULL) {
		rc = ENOMEM;
		goto error;
	}

	attr->aname = aname;
	attr->avalue = avalue;

	*rattr = attr;
	return EOK;
error:
	if (aname != NULL)
		free(aname);
	if (avalue != NULL)
		free(avalue);
	return rc;
}

/** Export SIF attribute to file.
 *
 * @param attr SIF attribute
 * @param f File
 * @return EOK on success, EIO on I/O error
 */
static errno_t sif_export_attr(sif_attr_t *attr, FILE *f)
{
	errno_t rc;

	rc = sif_export_name(attr->aname, f);
	if (rc != EOK)
		return rc;

	if (fputc('=', f) == EOF)
		return EIO;

	rc = sif_export_string(attr->avalue, f);
	if (rc != EOK)
		return rc;

	return EOK;
}

/** Export SIF node to file.
 *
 * @param node SIF node
 * @param f File
 * @return EOK on success, EIO on I/O error
 */
static errno_t sif_export_node(sif_node_t *node, FILE *f)
{
	errno_t rc;
	sif_attr_t *attr;
	sif_node_t *child;

	if (fputc('<', f) == EOF)
		return EIO;

	rc = sif_export_name(node->ntype, f);
	if (rc != EOK)
		return rc;

	/* Attributes */

	attr = sif_node_first_attr(node);
	while (attr != NULL) {
		if (fputc(' ', f) == EOF)
			return EIO;

		rc = sif_export_attr(attr, f);
		if (rc != EOK)
			return rc;

		attr = sif_node_next_attr(attr);
	}

	if (fputs(">\n", f) == EOF)
		return EIO;

	/* Child nodes */

	child = sif_node_first_child(node);
	while (child != NULL) {
		rc = sif_export_node(child, f);
		if (rc != EOK)
			return rc;

		child = sif_node_next_child(child);
	}

	if (fputs("</", f) == EOF)
		return EIO;

	rc = sif_export_name(node->ntype, f);
	if (rc != EOK)
		return rc;

	if (fputs(">\n", f) == EOF)
		return EIO;

	return EOK;
}

/** Import SIF node from file.
 *
 * @param parent Parent node
 * @param f File
 * @param rnode Place to store pointer to imported node
 * @param rendtag Place to store @c true iff end tag is encountered
 * @return EOK on success, EIO on I/O error
 */
static errno_t sif_import_node(sif_node_t *parent, FILE *f, sif_node_t **rnode,
    bool *rendtag)
{
	errno_t rc;
	sif_node_t *node = NULL;
	sif_node_t *child;
	sif_attr_t *attr = NULL;
	bool endtag;
	bool cendtag;
	char *ntype;
	int c;

	node = sif_node_new(parent);
	if (node == NULL)
		return ENOMEM;

	c = fgetc(f);
	while (isspace(c))
		c = fgetc(f);

	if (c != '<') {
		rc = EIO;
		goto error;
	}

	c = fgetc(f);
	if (c == '/') {
		endtag = true;
	} else {
		endtag = false;
		ungetc(c, f);
	}

	rc = sif_import_name(f, &ntype);
	if (rc != EOK)
		goto error;

	node->ntype = ntype;

	/* Attributes */

	c = fgetc(f);
	if (c == EOF) {
		rc = EIO;
		goto error;
	}

	while (c != '>') {
		/* End tags cannot have attributes */
		if (endtag) {
			rc = EIO;
			goto error;
		}

		while (isspace(c))
			c = fgetc(f);
		ungetc(c, f);

		rc = sif_import_attr(node, f, &attr);
		if (rc != EOK)
			goto error;

		odict_insert(&attr->lattrs, &node->attrs, NULL);

		c = fgetc(f);
		if (c == EOF) {
			rc = EIO;
			goto error;
		}
	}

	/* Child nodes */

	if (!endtag) {
		while (true) {
			rc = sif_import_node(node, f, &child, &cendtag);
			if (rc != EOK)
				goto error;

			if (cendtag) {
				sif_node_delete(child);
				break;
			}

			list_append(&child->lparent, &node->children);
		}
	}

	*rnode = node;
	*rendtag = endtag;
	return EOK;
error:
	sif_node_delete(node);
	return rc;
}

/** Get first attribute or a node.
 *
 * @param node SIF node
 * @return First attribute or @c NULL if there is none
 */
static sif_attr_t *sif_node_first_attr(sif_node_t *node)
{
	odlink_t *link;

	link = odict_first(&node->attrs);
	if (link == NULL)
		return NULL;

	return odict_get_instance(link, sif_attr_t, lattrs);
}

/** Get next attribute or a node.
 *
 * @param cur Current attribute
 * @return Next attribute or @c NULL if there is none
 */
static sif_attr_t *sif_node_next_attr(sif_attr_t *cur)
{
	odlink_t *link;

	link = odict_next(&cur->lattrs, &cur->node->attrs);
	if (link == NULL)
		return NULL;

	return odict_get_instance(link, sif_attr_t, lattrs);
}

/** Get key callback for ordered dictionary of node attributes.
 *
 * @param link Ordered dictionary link of attribute
 * @return Pointer to attribute name
 */
static void *sif_attr_getkey(odlink_t *link)
{
	return (void *)odict_get_instance(link, sif_attr_t, lattrs)->aname;
}

/** Comparison callback for  ordered dictionary of node attributes.
 *
 * @param a Name of first attribute
 * @param b Name of second attribute
 * @return Less than zero, zero or greater than zero, if a < b, a == b, a > b,
 *         respectively.
 */
static int sif_attr_cmp(void *a, void *b)
{
	char *ca, *cb;

	ca = (char *)a;
	cb = (char *)b;

	return str_cmp(ca, cb);
}

/** @}
 */