src/libedataserver/e-xml-utils.c

/* -*- 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 "evolution-data-server-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/catalog.h>
#include <libxml/tree.h>
#include <libxml/xpathInternals.h>

#include <glib/gstdio.h>

#include "e-xml-utils.h"

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

/**
 * e_xml_initialize_in_main: (skip)
 *
 * Initializes libxml library global memory. This should be called
 * in the main thread. The function does nothing, when it had been
 * called already.
 *
 * Since: 3.28
 **/
void
e_xml_initialize_in_main (void)
{
	static volatile guint called = 0;

	if (!g_atomic_int_or (&called, 1)) {
		xmlInitMemory ();
		xmlInitThreads ();
		xmlInitGlobals ();
		xmlInitializeCatalog ();
		xmlInitParser ();
	}
}

/**
 * e_xml_parse_file: (skip)
 * @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: (transfer full): an XML document structure, or %NULL
 **/
xmlDoc *
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,
                 xmlDoc *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: (skip)
 * @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: (nullable): 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;
}

/**
 * e_xml_parse_data: (skip)
 * @data: (array length=length) (element-type guint8): an XML data
 * @length: length of data, should be greated than zero
 *
 * Parses XML data into an #xmlDocPtr. Free returned pointer
 * with xmlFreeDoc(), when no longer needed.
 *
 * Returns: (nullable) (transfer full): a new #xmlDocPtr with parsed @data,
 *    or %NULL on error.
 *
 * Since: 3.26
 **/
xmlDoc *
e_xml_parse_data (gconstpointer data,
		  gsize length)
{
	g_return_val_if_fail (data != NULL, NULL);
	g_return_val_if_fail (length > 0, NULL);

	return xmlReadMemory (data, length, "data.xml", NULL, XML_PARSE_NOWARNING | XML_PARSE_RECOVER);
}

/**
 * e_xml_new_xpath_context_with_namespaces: (skip)
 * @doc: an #xmlDocPtr
 * @...: %NULL-terminated list of pairs (prefix, href) with namespaces
 *
 * Creates a new #xmlXPathContextPtr on @doc with preregistered
 * namespaces. The namepsaces are pair of (prefix, href), terminated
 * by %NULL.
 *
 * Returns: (transfer full): a new #xmlXPathContextPtr. Free the returned
 *    pointer with xmlXPathFreeContext() when no longer needed.
 *
 * Since: 3.26
 **/
xmlXPathContext *
e_xml_new_xpath_context_with_namespaces (xmlDoc *doc,
					 ...)
{
	xmlXPathContextPtr xpath_ctx;
	va_list va;
	const gchar *prefix;

	g_return_val_if_fail (doc != NULL, NULL);

	xpath_ctx = xmlXPathNewContext (doc);
	g_return_val_if_fail (xpath_ctx != NULL, NULL);

	va_start (va, doc);

	while (prefix = va_arg (va, const gchar *), prefix) {
		const gchar *href = va_arg (va, const gchar *);

		if (!href) {
			g_warn_if_fail (href != NULL);
			break;
		}

		xmlXPathRegisterNs (xpath_ctx, (const xmlChar *) prefix, (const xmlChar *) href);
	}

	va_end (va);

	return xpath_ctx;
}

/**
 * e_xml_xpath_context_register_namespaces: (skip)
 * @xpath_ctx: an #xmlXPathContextPtr
 * @prefix: namespace prefix
 * @href: namespace href
 * @...: %NULL-terminated list of pairs (prefix, href) with additional namespaces
 *
 * Registers one or more additional namespaces. It's a caller's error
 * to try to register a namespace with the same prefix again, unless
 * the prefix uses the same namespace href.
 *
 * Since: 3.26
 **/
void
e_xml_xpath_context_register_namespaces (xmlXPathContext *xpath_ctx,
					 const gchar *prefix,
					 const gchar *href,
					 ...)
{
	va_list va;
	const gchar *used_href;

	g_return_if_fail (xpath_ctx != NULL);
	g_return_if_fail (prefix != NULL);
	g_return_if_fail (href != NULL);

	used_href = (const gchar *) xmlXPathNsLookup (xpath_ctx, (const xmlChar *) prefix);
	if (used_href && g_strcmp0 (used_href, href) != 0) {
		g_warning ("%s: Trying to register prefix '%s' with href '%s', but it already points to '%s'",
			G_STRFUNC, prefix, href, used_href);
	} else if (!used_href) {
		xmlXPathRegisterNs (xpath_ctx, (const xmlChar *) prefix, (const xmlChar *) href);
	}

	va_start (va, href);

	while (prefix = va_arg (va, const gchar *), prefix) {
		href = va_arg (va, const gchar *);

		if (!href) {
			g_warn_if_fail (href != NULL);
			break;
		}

		used_href = (const gchar *) xmlXPathNsLookup (xpath_ctx, (const xmlChar *) prefix);
		if (used_href && g_strcmp0 (used_href, href) != 0) {
			g_warning ("%s: Trying to register prefix '%s' with href '%s', but it already points to '%s'",
				G_STRFUNC, prefix, href, used_href);
		} else if (!used_href) {
			xmlXPathRegisterNs (xpath_ctx, (const xmlChar *) prefix, (const xmlChar *) href);
		}
	}

	va_end (va);
}

/**
 * e_xml_xpath_eval: (skip)
 * @xpath_ctx: an #xmlXPathContextPtr
 * @format: printf-like format specifier of path to evaluate
 * @...: arguments for the @format
 *
 * Evaluates path specified by @format and returns its #xmlXPathObjectPtr,
 * in case the path evaluates to a non-empty node set. See also
 * e_xml_xpath_eval_as_string() which evaluates the path to string.
 *
 * Returns: (nullable) (transfer full): a new #xmlXPathObjectPtr which
 *    references given path, or %NULL if path cannot be found or when
 *    it evaluates to an empty nodeset. Free returned pointer with
 *    xmlXPathFreeObject(), when no longer needed.
 *
 * Since: 3.26
 **/
xmlXPathObject *
e_xml_xpath_eval (xmlXPathContext *xpath_ctx,
		  const gchar *format,
		  ...)
{
	xmlXPathObjectPtr object;
	va_list va;
	gchar *expr;

	g_return_val_if_fail (xpath_ctx != NULL, NULL);
	g_return_val_if_fail (format != NULL, NULL);

	va_start (va, format);
	expr = g_strdup_vprintf (format, va);
	va_end (va);

	object = xmlXPathEvalExpression ((const xmlChar *) expr, xpath_ctx);
	g_free (expr);

	if (!object)
		return NULL;

	if (object->type == XPATH_NODESET &&
	    xmlXPathNodeSetIsEmpty (object->nodesetval)) {
		xmlXPathFreeObject (object);
		return NULL;
	}

	return object;
}

/**
 * e_xml_xpath_eval_as_string: (skip)
 * @xpath_ctx: an #xmlXPathContextPtr
 * @format: printf-like format specifier of path to evaluate
 * @...: arguments for the @format
 *
 * Evaluates path specified by @format and returns its result as string,
 * in case the path evaluates to a non-empty node set. See also
 * e_xml_xpath_eval() which evaluates the path to an #xmlXPathObjectPtr.
 *
 * Returns: (nullable) (transfer full): a new string which contains value
 *    of the given path, or %NULL if path cannot be found or when
 *    it evaluates to an empty nodeset. Free returned pointer with
 *    g_free(), when no longer needed.
 *
 * Since: 3.26
 **/
gchar *
e_xml_xpath_eval_as_string (xmlXPathContext *xpath_ctx,
			    const gchar *format,
			    ...)
{
	xmlXPathObjectPtr object;
	va_list va;
	gchar *expr, *value;

	g_return_val_if_fail (xpath_ctx != NULL, NULL);
	g_return_val_if_fail (format != NULL, NULL);

	va_start (va, format);
	expr = g_strdup_vprintf (format, va);
	va_end (va);

	if (!g_str_has_prefix (format, "string(")) {
		gchar *tmp = expr;

		expr = g_strconcat ("string(", expr, ")", NULL);

		g_free (tmp);
	}

	object = e_xml_xpath_eval (xpath_ctx, "%s", expr);
	g_free (expr);

	if (!object)
		return NULL;

	if (object->type == XPATH_STRING &&
	    *object->stringval)
		value = g_strdup ((const gchar *) object->stringval);
	else
		value = NULL;

	xmlXPathFreeObject (object);

	return value;
}

/**
 * e_xml_xpath_eval_exists: (skip)
 * @xpath_ctx: an #xmlXPathContextPtr
 * @format: printf-like format specifier of path to evaluate
 * @...: arguments for the @format
 *
 * Evaluates path specified by @format and returns whether it exists.
 *
 * Returns: %TRUE, when the given XPath exists, %FALSE otherwise.
 *
 * Since: 3.26
 **/
gboolean
e_xml_xpath_eval_exists (xmlXPathContext *xpath_ctx,
			 const gchar *format,
			 ...)
{
	xmlXPathObjectPtr object;
	va_list va;
	gchar *expr;

	g_return_val_if_fail (xpath_ctx != NULL, FALSE);
	g_return_val_if_fail (format != NULL, FALSE);

	va_start (va, format);
	expr = g_strdup_vprintf (format, va);
	va_end (va);

	object = e_xml_xpath_eval (xpath_ctx, "%s", expr);
	g_free (expr);

	if (!object)
		return FALSE;

	xmlXPathFreeObject (object);

	return TRUE;
}

/**
 * e_xml_is_element_name: (skip)
 * @node: (nullable): an #xmlNode
 * @ns_href: (nullable): a namespace href the node should have set, or %NULL for none namespace
 * @name: an element name to search for
 *
 * Returns: Whether the @node is an element node of name @name and with a namespace href set to @ns_href
 *
 * Since: 3.38
 **/
gboolean
e_xml_is_element_name (xmlNode *node,
		       const gchar *ns_href,
		       const gchar *name)
{
	if (!node || node->type != XML_ELEMENT_NODE)
		return FALSE;

	if (g_strcmp0 ((const gchar *) node->name, name) == 0) {
		if (!ns_href) {
			if (!node->ns)
				return TRUE;
		} else if (node->ns) {
			xmlNsPtr nsPtr;

			if (g_strcmp0 ((const gchar *) node->ns->href, ns_href) == 0)
				return TRUE;

			nsPtr = xmlSearchNsByHref (node->doc, node, (const xmlChar *) ns_href);

			if (nsPtr && node->ns == nsPtr)
				return TRUE;
		}
	}

	return FALSE;
}

/**
 * e_xml_find_sibling: (skip)
 * @sibling: (nullable): an #xmlNode, where to start searching
 * @ns_href: (nullable): a namespace href the node should have set, or %NULL for none namespace
 * @name: an element name to search for
 *
 * Searches the sibling nodes of the @sibling for an element named @name in namespace @ns_href.
 * It checks the @sibling itself too, but it doesn't check the previous siblings of the @sibling.
 *
 * Returns: (transfer none) (nullable): an #xmlNode of the given name, or %NULL, if not found
 *    It also returns %NULL, when the @sibling is %NULL.
 *
 * See: e_xml_find_next_sibling(), e_xml_find_child()
 *
 * Since: 3.38
 **/
xmlNode *
e_xml_find_sibling (xmlNode *sibling,
		    const gchar *ns_href,
		    const gchar *name)
{
	xmlNode *node;

	for (node = sibling; node; node = xmlNextElementSibling (node)) {
		if (e_xml_is_element_name (node, ns_href, name))
			break;
	}

	return node;
}

/**
 * e_xml_find_next_sibling: (skip)
 * @sibling: (nullable): an #xmlNode, where to search from
 * @ns_href: (nullable): a namespace href the node should have set, or %NULL for none namespace
 * @name: an element name to search for
 *
 * Searches for the next sibling node of the @sibling for an element named @name in namespace @ns_href.
 * Unlike e_xml_find_sibling(), it skips the @sibling itself.
 *
 * Returns: (transfer none) (nullable): an #xmlNode of the given name, or %NULL, if not found
 *    It also returns %NULL, when the @sibling is %NULL.
 *
 * See: e_xml_find_sibling(), e_xml_find_child()
 *
 * Since: 3.38
 **/
xmlNode *
e_xml_find_next_sibling (xmlNode *sibling,
			 const gchar *ns_href,
			 const gchar *name)
{
	if (!sibling)
		return NULL;

	return e_xml_find_sibling (sibling->next, ns_href, name);
}

/**
 * e_xml_find_child: (skip)
 * @parent: (nullable): an #xmlNode, parent of which immediate children to search
 * @ns_href: (nullable): a namespace href the node should have set, or %NULL for none namespace
 * @name: an element name to search for
 *
 * Searches the children nodes of the @parent for an element named @name in namespace @ns_href.
 *
 * Returns: (transfer none) (nullable): an #xmlNode of the given name, or %NULL, if not found.
 *    It also returns %NULL, when the @parent is %NULL.
 *
 * See: e_xml_find_sibling(), e_xml_find_children_nodes()
 *
 * Since: 3.38
 **/
xmlNode *
e_xml_find_child (xmlNode *parent,
		  const gchar *ns_href,
		  const gchar *name)
{
	if (!parent)
		return NULL;

	return e_xml_find_sibling (parent->children, ns_href, name);
}

/**
 * e_xml_dup_node_content: (skip)
 * @node: (nullable): an #xmlNode
 *
 * Duplicates content of the @node. If the @node is %NULL, then the
 * function does nothing and returns also %NULL.
 *
 * Unlike e_xml_get_node_text(), this includes also any element sub-structure
 * of the @node, if any such exists.
 *
 * Returns: (transfer full) (nullable): the @node content as #xmlChar string,
 *    or %NULL, when the content could not be read or was not set. Free
 *    the non-%NULL value with xmlFree(), when no longer needed.
 *
 * See: e_xml_find_child_and_dup_content(), e_xml_get_node_text()
 *
 * Since: 3.38
 **/
xmlChar *
e_xml_dup_node_content (const xmlNode *node)
{
	if (!node)
		return NULL;

	return xmlNodeGetContent (node);
}

/**
 * e_xml_find_child_and_dup_content: (skip)
 * @parent: (nullable): an #xmlNode, parent of which immediate children to search
 * @ns_href: (nullable): a namespace href the node should have set, or %NULL for none namespace
 * @name: an element name to search for
 *
 * Searches the children nodes of the @parent for an element named @name in namespace @ns_href
 * and returns its content. This combines e_xml_find_child() and e_xml_dup_node_content() calls.
 *
 * Returns: (transfer full) (nullable): the found node content as #xmlChar string,
 *    or %NULL, when the node could not be found or the content could not be read
 *    or was not set. Free the non-%NULL value with xmlFree(), when no longer needed.
 *
 * See: e_xml_find_child_and_get_text()
 *
 * Since: 3.38
 **/
xmlChar *
e_xml_find_child_and_dup_content (xmlNode *parent,
				  const gchar *ns_href,
				  const gchar *name)
{
	xmlNode *tmp;

	tmp = e_xml_find_child (parent, ns_href, name);

	if (!tmp)
		return NULL;

	return e_xml_dup_node_content (tmp);
}

/**
 * e_xml_get_node_text: (skip)
 * @node: (nullable): an #xmlNode
 *
 * Retrieves content of the @node. If the @node is %NULL, then the
 * function does nothing and returns also %NULL.
 *
 * This is similar to e_xml_dup_node_content(), except it does not
 * allocate new memory for the string. It also doesn't traverse
 * the element structure, is returns the first text node's value
 * only. It can be used to avoid unnecessary allocations, when
 * reading element values with a single text node as a child.
 *
 * Returns: (transfer none) (nullable): The @node content, or %NULL.
 *
 * See: e_xml_dup_node_content()
 *
 * Since: 3.38
 **/
const xmlChar *
e_xml_get_node_text (const xmlNode *node)
{
	xmlNode *child;

	if (!node)
		return NULL;

	if (node->type == XML_TEXT_NODE || node->type == XML_CDATA_SECTION_NODE)
		return node->content;

	for (child = node->children; child; child = child->next) {
		if (child->type == XML_TEXT_NODE || child->type == XML_CDATA_SECTION_NODE)
			return child->content;
	}

	return NULL;
}

/**
 * e_xml_find_child_and_get_text: (skip)
 * @parent: (nullable): an #xmlNode, parent of which immediate children to search
 * @ns_href: (nullable): a namespace href the node should have set, or %NULL for none namespace
 * @name: an element name to search for
 *
 * Searches the children nodes of the @parent for an element named @name in namespace @ns_href
 * and returns its text content.
 *
 * It combines e_xml_find_child() and e_xml_get_node_text() calls.
 *
 * Returns: (transfer none) (nullable): the found node text as #xmlChar string,
 *    or %NULL, when the node could not be found or the content could not be read
 *    or was not set.
 *
 * See: e_xml_find_child_and_dup_content(), e_xml_find_children_nodes()
 *
 * Since: 3.38
 **/
const xmlChar *
e_xml_find_child_and_get_text (xmlNode *parent,
			       const gchar *ns_href,
			       const gchar *name)
{
	xmlNode *tmp;

	tmp = e_xml_find_child (parent, ns_href, name);

	if (!tmp)
		return NULL;

	return e_xml_get_node_text (tmp);
}

/**
 * e_xml_find_children_nodes: (skip)
 * @parent: an #xmlNode, whose children to search
 * @count: how many nodes will be read
 * @...: triple of arguments describing the nodes and their out variable
 *
 * Retrieve multiple nodes in one go, in an efficient way. It can be
 * quicker than traversing the children of the @parent @count times
 * in certain circumstances.
 *
 * The variable parameters expect triple of:
 *   const gchar *ns_href;
 *   const gchar *name;
 *   xmlNode **out_node;
 * where the ns_href is a namespace href the node should have set,
 * or %NULL for none namespace; the name is an element name to search for.
 * The names should not be included more than once.
 *
 * Since: 3.38
 **/
void
e_xml_find_children_nodes (xmlNode *parent,
			   guint count,
			   ...)
{
	struct _data {
		const gchar *ns_href;
		const gchar *name;
		xmlNode **out_node;
	} *data;
	va_list args;
	xmlNode *node;
	guint ii;

	g_return_if_fail (count > 0);

	data = g_alloca (sizeof (struct _data) * count);

	va_start (args, count);

	for (ii = 0; ii < count; ii++) {
		data[ii].ns_href = va_arg (args, const gchar *);
		data[ii].name = va_arg (args, const gchar *);
		data[ii].out_node = va_arg (args, xmlNode **);

		*(data[ii].out_node) = NULL;
	}

	va_end (args);

	for (node = parent->children; node; node = count ? xmlNextElementSibling (node) : NULL) {
		for (ii = 0; ii < count; ii++) {
			if (e_xml_is_element_name (node, data[ii].ns_href, data[ii].name)) {
				*(data[ii].out_node) = node;
				count--;

				if (ii < count)
					data[ii] = data[count];

				break;
			}
		}
	}
}

/**
 * e_xml_find_in_hierarchy: (skip)
 * @parent: (nullable): an #xmlNode, or %NULL, in which case function does nothing and just returns %NULL
 * @child_ns_href: (nullable): a namespace href the node should have set, or %NULL for none namespace
 * @child_name: an element name to search for
 * @...: a two-%NULL-terminated pair of hierarchy children
 *
 * Checks whether the @parent has a hierarchy of children described by pair
 * of 'ns_href' and 'name'.
 *
 * Note: It requires two %NULL-s at the end of the arguments, because the `ns_href' can
 *    be %NULL, thus it could not distinguish between no namespace href and the end of
 *    the hierarchy children, thus it stops only on the 'name' being %NULL.
 *
 * Returns: (transfer none) (nullable): an #xmlNode referencing the node in the hierarchy
 *    of the children of the @parent, or %NULL, when no such found.
 *
 * Since: 3.38
 **/
xmlNode *
e_xml_find_in_hierarchy (xmlNode *parent,
			 const gchar *child_ns_href,
			 const gchar *child_name,
			 ...)
{
	xmlNode *node;
	va_list va;

	if (!parent)
		return NULL;

	node = e_xml_find_child (parent, child_ns_href, child_name);

	if (!node)
		return NULL;

	va_start (va, child_name);

	while (node) {
		child_ns_href = va_arg (va, const gchar *);
		child_name = va_arg (va, const gchar *);

		if (!child_name)
			break;

		node = e_xml_find_child (node, child_ns_href, child_name);
	}

	va_end (va);

	return child_name ? NULL : node;
}