/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 *
 * This library is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library. If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <config.h>

#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#ifndef O_BINARY
#define O_BINARY 0
#endif

#include <libxml/parser.h>
#include <libxml/tree.h>

#include <glib/gstdio.h>

#include "e-xml-utils.h"

#ifdef G_OS_WIN32
#define fsync(fd) 0
#endif

/**
 * e_xml_parse_file:
 * @filename: path to an XML file
 *
 * Reads a local XML file and parses the contents into an XML document
 * structure.  If the XML file cannot be read or its contents are malformed,
 * the function returns %NULL.
 *
 * Returns: an XML document structure, or %NULL
 **/
xmlDocPtr
e_xml_parse_file (const gchar *filename)
{
	xmlDocPtr result = NULL;

	GMappedFile *mapped_file;

	mapped_file = g_mapped_file_new (filename, FALSE, NULL);
	if (mapped_file) {
		result = xmlParseMemory (
			g_mapped_file_get_contents (mapped_file),
			g_mapped_file_get_length (mapped_file));
		g_mapped_file_unref (mapped_file);
	}

	return result;
}

/**
 * e_xml_save_file:
 * @filename: path to a file to save to
 * @doc: an XML document structure
 *
 * Writes the given XML document structure to the file given by @filename.
 * If an error occurs while saving, the function returns -1 and sets errno.
 *
 * Returns: 0 on success, -1 on failure
 **/
gint
e_xml_save_file (const gchar *filename,
                 xmlDocPtr doc)
{
	gchar *filesave;
	xmlChar *xmlbuf;
	gsize n, written = 0;
	gint ret, fd, size;
	gint errnosave;
	gssize w;
	gchar *dirname = g_path_get_dirname (filename);
	gchar *basename = g_path_get_basename (filename);
	gchar *savebasename = g_strconcat (".#", basename, NULL);

	g_free (basename);
	filesave = g_build_filename (dirname, savebasename, NULL);
	g_free (savebasename);
	g_free (dirname);

	fd = g_open (filesave, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0600);
	if (fd == -1) {
		g_free (filesave);
		return -1;
	}

	xmlDocDumpFormatMemory (doc, &xmlbuf, &size, TRUE);
	if (size <= 0) {
		close (fd);
		g_unlink (filesave);
		g_free (filesave);
		errno = ENOMEM;
		return -1;
	}

	n = (gsize) size;
	do {
		do {
			w = write (fd, xmlbuf + written, n - written);
		} while (w == -1 && errno == EINTR);

		if (w > 0)
			written += w;
	} while (w != -1 && written < n);

	xmlFree (xmlbuf);

	if (written < n || fsync (fd) == -1) {
		errnosave = errno;
		close (fd);
		g_unlink (filesave);
		g_free (filesave);
		errno = errnosave;
		return -1;
	}

	while ((ret = close (fd)) == -1 && errno == EINTR)
		;

	if (ret == -1) {
		g_free (filesave);
		return -1;
	}

	if (g_rename (filesave, filename) == -1) {
		errnosave = errno;
		g_unlink (filesave);
		g_free (filesave);
		errno = errnosave;
		return -1;
	}
	g_free (filesave);

	return 0;
}

/**
 * e_xml_get_child_by_name:
 * @parent: an XML node structure
 * @child_name: element name of a child node
 *
 * Attempts to find a child element of @parent named @child_name.
 * If no such child exists, the function returns %NULL.
 *
 * Returns: a child XML node structure, or %NULL
 **/
xmlNode *
e_xml_get_child_by_name (const xmlNode *parent,
                         const xmlChar *child_name)
{
	xmlNode *child;

	g_return_val_if_fail (parent != NULL, NULL);
	g_return_val_if_fail (child_name != NULL, NULL);

	for (child = parent->xmlChildrenNode; child != NULL; child = child->next) {
		if (xmlStrcmp (child->name, child_name) == 0) {
			return child;
		}
	}
	return NULL;
}