githubmirror/libxmlb

src/xb-query.c
603 строки15 KB
Richard Hughes
Limit the number of predicates per XPath section
15 май 2026, 16:07
15 май 2026, 16:07092c71c
/*
 * Copyright 2018 Richard Hughes <richard@hughsie.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 */

#define G_LOG_DOMAIN "XbSilo"

#include "config.h"

#include <gio/gio.h>

#include "xb-machine.h"
#include "xb-opcode-private.h"
#include "xb-query-private.h"
#include "xb-silo-private.h"
#include "xb-stack-private.h"

#define XB_QUERY_SECTION_MAX   100
#define XB_QUERY_PREDICATE_MAX 20

typedef struct {
	GPtrArray *sections; /* of XbQuerySection */
	XbQueryFlags flags;
	gchar *xpath;
	guint limit;
} XbQueryPrivate;

G_DEFINE_TYPE_WITH_PRIVATE(XbQuery, xb_query, G_TYPE_OBJECT)
#define GET_PRIVATE(o) (xb_query_get_instance_private(o))

typedef struct {
	XbSilo *silo;
} XbQueryParseContext;

/**
 * xb_query_get_sections:
 * @self: a #XbQuery
 *
 * Gets the sections that make up the query.
 *
 * Returns: (transfer none) (element-type XbQuerySection): sections
 *
 * Since: 0.1.4
 **/
GPtrArray *
xb_query_get_sections(XbQuery *self)
{
	XbQueryPrivate *priv = GET_PRIVATE(self);
	g_return_val_if_fail(XB_IS_QUERY(self), NULL);
	return priv->sections;
}

/**
 * xb_query_get_xpath:
 * @self: a #XbQuery
 *
 * Gets the XPath string that created the query.
 *
 * Returns: string
 *
 * Since: 0.1.4
 **/
const gchar *
xb_query_get_xpath(XbQuery *self)
{
	XbQueryPrivate *priv = GET_PRIVATE(self);
	g_return_val_if_fail(XB_IS_QUERY(self), NULL);
	return priv->xpath;
}

static gchar *
xb_query_section_to_string(XbQuerySection *sect)
{
	GString *str = g_string_new(NULL);
	if (sect->kind == XB_SILO_QUERY_KIND_PARENT)
		g_string_append(str, "..");
	else if (sect->kind == XB_SILO_QUERY_KIND_WILDCARD)
		g_string_append(str, "*");
	else
		g_string_append(str, sect->element);
	if (sect->predicates != NULL && sect->predicates->len > 0) {
		g_string_append(str, "[");
		for (guint j = 0; j < sect->predicates->len; j++) {
			XbStack *stack = g_ptr_array_index(sect->predicates, j);
			g_autofree gchar *tmp = xb_stack_to_string(stack);
			g_string_append(str, tmp);
		}
		g_string_append(str, "]");
	}
	return g_string_free(str, FALSE);
}

/**
 * xb_query_to_string:
 * @self: a #XbQuery
 *
 * Gets the XPath that was used for the query.
 *
 * Returns: string
 *
 * Since: 0.1.13
 **/
gchar *
xb_query_to_string(XbQuery *self)
{
	XbQueryPrivate *priv = GET_PRIVATE(self);
	GString *str = g_string_new(NULL);
	for (guint i = 0; i < priv->sections->len; i++) {
		XbQuerySection *sect = g_ptr_array_index(priv->sections, i);
		g_autofree gchar *tmp = xb_query_section_to_string(sect);
		g_string_append(str, tmp);
		if (i != priv->sections->len - 1)
			g_string_append(str, "/");
	}
	return g_string_free(str, FALSE);
}

/**
 * xb_query_get_limit:
 * @self: a #XbQuery
 *
 * Gets the results limit on this query, where 0 is 'all'.
 *
 * Returns: integer, default 0
 *
 * Deprecated: 0.3.0: This is not thread-safe. Use xb_query_context_get_limit()
 *     instead.
 * Since: 0.1.4
 **/
guint
xb_query_get_limit(XbQuery *self)
{
	XbQueryPrivate *priv = GET_PRIVATE(self);
	g_return_val_if_fail(XB_IS_QUERY(self), 0);
	return priv->limit;
}

/**
 * xb_query_set_limit:
 * @self: a #XbQuery
 * @limit: integer
 *
 * Sets the results limit on this query, where 0 is 'all'.
 *
 * Deprecated: 0.3.0: This is not thread-safe. Use xb_query_context_set_limit()
 *     instead.
 * Since: 0.1.4
 **/
void
xb_query_set_limit(XbQuery *self, guint limit)
{
	XbQueryPrivate *priv = GET_PRIVATE(self);
	g_return_if_fail(XB_IS_QUERY(self));
	priv->limit = limit;
}

/**
 * xb_query_get_flags:
 * @self: a #XbQuery
 *
 * Gets the flags used for this query.
 *
 * Returns: #XbQueryFlags, default %XB_QUERY_FLAG_NONE
 *
 * Deprecated: 0.3.0: This is not thread-safe. Use xb_query_context_get_flags()
 *     instead.
 * Since: 0.1.15
 **/
XbQueryFlags
xb_query_get_flags(XbQuery *self)
{
	XbQueryPrivate *priv = GET_PRIVATE(self);
	g_return_val_if_fail(XB_IS_QUERY(self), 0);
	return priv->flags;
}

/**
 * xb_query_set_flags:
 * @self: a #XbQuery
 * @flags: a #XbQueryFlags, e.g. %XB_QUERY_FLAG_USE_INDEXES
 *
 * Sets the flags to use for this query.
 *
 * Deprecated: 0.3.0: This is not thread-safe. Use xb_query_context_set_flags()
 *     instead.
 * Since: 0.1.15
 **/
void
xb_query_set_flags(XbQuery *self, XbQueryFlags flags)
{
	XbQueryPrivate *priv = GET_PRIVATE(self);
	g_return_if_fail(XB_IS_QUERY(self));
	priv->flags = flags;
}

static XbOpcode *
xb_query_get_bound_opcode(XbQuery *self, guint idx)
{
	XbQueryPrivate *priv = GET_PRIVATE(self);
	guint idx_cnt = 0;

	for (guint i = 0; i < priv->sections->len; i++) {
		XbQuerySection *section = g_ptr_array_index(priv->sections, i);
		if (section->predicates == NULL)
			continue;
		for (guint j = 0; j < section->predicates->len; j++) {
			XbStack *stack = g_ptr_array_index(section->predicates, j);
			for (guint k = 0; k < xb_stack_get_size(stack); k++) {
				XbOpcode *op = xb_stack_peek(stack, k);
				if (xb_opcode_is_binding(op)) {
					if (idx == idx_cnt++)
						return op;
				}
			}
		}
	}
	return NULL;
}

/**
 * xb_query_bind_str:
 * @self: a #XbQuery
 * @idx: an integer index
 * @str: string to assign to the bound variable
 * @error: a #GError, or %NULL
 *
 * Assigns a string to a bound value specified using `?`.
 *
 * Returns: %TRUE if the @idx existed
 *
 * Since: 0.1.4
 * Deprecated: 0.3.0: Use #XbValueBindings and xb_value_bindings_bind_str()
 *     instead. That keeps the value bindings separate from the #XbQuery,
 *     allowing queries to be re-used over time and between threads.
 **/
gboolean
xb_query_bind_str(XbQuery *self, guint idx, const gchar *str, GError **error)
{
	G_GNUC_BEGIN_IGNORE_DEPRECATIONS
	XbOpcode *op;

	g_return_val_if_fail(XB_IS_QUERY(self), FALSE);
	g_return_val_if_fail(error == NULL || *error == NULL, FALSE);

	/* get the correct opcode */
	op = xb_query_get_bound_opcode(self, idx);
	if (op == NULL) {
		g_set_error(error,
			    G_IO_ERROR,
			    G_IO_ERROR_INVALID_ARGUMENT,
			    "no bound opcode with index %u",
			    idx);
		return FALSE;
	}
	xb_opcode_bind_str(op, g_strdup(str), g_free);
	return TRUE;
	G_GNUC_END_IGNORE_DEPRECATIONS
}

/**
 * xb_query_bind_val:
 * @self: a #XbQuery
 * @idx: an integer index
 * @val: value to assign to the bound variable
 * @error: a #GError, or %NULL
 *
 * Assigns a string to a bound value specified using `?`.
 *
 * Returns: %TRUE if the @idx existed
 *
 * Since: 0.1.4
 * Deprecated: 0.3.0: Use #XbValueBindings and xb_value_bindings_bind_val()
 *     instead. That keeps the value bindings separate from the #XbQuery,
 *     allowing queries to be re-used over time and between threads.
 **/
gboolean
xb_query_bind_val(XbQuery *self, guint idx, guint32 val, GError **error)
{
	G_GNUC_BEGIN_IGNORE_DEPRECATIONS
	XbOpcode *op;

	g_return_val_if_fail(XB_IS_QUERY(self), FALSE);
	g_return_val_if_fail(error == NULL || *error == NULL, FALSE);

	/* get the correct opcode */
	op = xb_query_get_bound_opcode(self, idx);
	if (op == NULL) {
		g_set_error(error,
			    G_IO_ERROR,
			    G_IO_ERROR_INVALID_ARGUMENT,
			    "no bound opcode with index %u",
			    idx);
		return FALSE;
	}
	xb_opcode_bind_val(op, val);
	return TRUE;
	G_GNUC_END_IGNORE_DEPRECATIONS
}

static void
xb_query_section_free(XbQuerySection *section)
{
	if (section->predicates != NULL)
		g_ptr_array_unref(section->predicates);
	g_free(section->element);
	g_slice_free(XbQuerySection, section);
}

G_DEFINE_AUTOPTR_CLEANUP_FUNC(XbQuerySection, xb_query_section_free)

static gboolean
xb_query_repair_opcode_texi(XbQuery *self,
			    XbQueryParseContext *context,
			    XbOpcode *op,
			    GError **error)
{
	if (xb_opcode_get_val(op) == XB_SILO_UNSET) {
		const gchar *tmp = xb_opcode_get_str(op);
		guint32 val = xb_silo_strtab_index_lookup(context->silo, tmp);
		if (val == XB_SILO_UNSET) {
			g_set_error(error,
				    G_IO_ERROR,
				    G_IO_ERROR_INVALID_ARGUMENT,
				    "indexed string '%s' was unfound",
				    tmp);
			return FALSE;
		}
		xb_opcode_set_val(op, val);
	}
	return TRUE;
}

/* Returns an error if the XPath is invalid. */
static gboolean
xb_query_parse_predicate(XbQuery *self,
			 XbQueryParseContext *context,
			 XbQuerySection *section,
			 const gchar *text,
			 gssize text_len,
			 GError **error)
{
	XbQueryPrivate *priv = GET_PRIVATE(self);
	XbMachineParseFlags machine_flags = XB_MACHINE_PARSE_FLAG_NONE;
	g_autoptr(XbStack) opcodes = NULL;

	/* set flags */
	if (priv->flags & XB_QUERY_FLAG_OPTIMIZE)
		machine_flags |= XB_MACHINE_PARSE_FLAG_OPTIMIZE;

	/* parse */
	opcodes = xb_machine_parse_full(xb_silo_get_machine(context->silo),
					text,
					text_len,
					machine_flags,
					error);
	if (opcodes == NULL)
		return FALSE;

	/* repair or convert the indexed strings */
	if (priv->flags & XB_QUERY_FLAG_USE_INDEXES) {
		for (guint i = 0; i < xb_stack_get_size(opcodes); i++) {
			XbOpcode *op = xb_stack_peek(opcodes, i);
			if (xb_opcode_get_kind(op) != XB_OPCODE_KIND_INDEXED_TEXT)
				continue;
			if (!xb_query_repair_opcode_texi(self, context, op, error))
				return FALSE;
		}
	} else {
		for (guint i = 0; i < xb_stack_get_size(opcodes); i++) {
			XbOpcode *op = xb_stack_peek(opcodes, i);
			if (xb_opcode_get_kind(op) == XB_OPCODE_KIND_INDEXED_TEXT)
				xb_opcode_set_kind(op, XB_OPCODE_KIND_TEXT);
		}
	}

	/* create array if it does not exist */
	if (section->predicates == NULL)
		section->predicates =
		    g_ptr_array_new_with_free_func((GDestroyNotify)xb_stack_unref);
	g_ptr_array_add(section->predicates, g_steal_pointer(&opcodes));
	if (section->predicates->len > XB_QUERY_PREDICATE_MAX) {
		g_set_error_literal(error,
				    G_IO_ERROR,
				    G_IO_ERROR_INVALID_DATA,
				    "too many predicates in XPath section");
		return FALSE;
	}
	return TRUE;
}

/* Returns an error if the XPath is invalid. */
static XbQuerySection *
xb_query_parse_section(XbQuery *self,
		       XbQueryParseContext *context,
		       const gchar *xpath,
		       GError **error)
{
	g_autoptr(XbQuerySection) section = g_slice_new0(XbQuerySection);
	guint start = 0;

	/* common XPath sections */
	if (g_strcmp0(xpath, "parent::*") == 0 || g_strcmp0(xpath, "..") == 0) {
		section->kind = XB_SILO_QUERY_KIND_PARENT;
		return g_steal_pointer(&section);
	}

	/* parse element and predicate */
	for (guint i = 0; xpath[i] != '\0'; i++) {
		if (start == 0 && xpath[i] == '[') {
			if (section->element == NULL)
				section->element = g_strndup(xpath, i);
			start = i;
			continue;
		}
		if (start > 0 && xpath[i] == ']') {
			if (!xb_query_parse_predicate(self,
						      context,
						      section,
						      xpath + start + 1,
						      i - start - 1,
						      error)) {
				return NULL;
			}
			start = 0;
			continue;
		}
	}

	/* incomplete predicate */
	if (start != 0) {
		g_set_error(error,
			    G_IO_ERROR,
			    G_IO_ERROR_INVALID_ARGUMENT,
			    "predicate %s was unfinished, missing ']'",
			    xpath + start);
		return NULL;
	}

	if (section->element == NULL)
		section->element = g_strdup(xpath);
	if (g_strcmp0(section->element, "child::*") == 0 || g_strcmp0(section->element, "*") == 0) {
		section->kind = XB_SILO_QUERY_KIND_WILDCARD;
		return g_steal_pointer(&section);
	}

	/* This may result in @element_idx being set to %XB_SILO_UNSET if the
	 * given element (`section->element`) is not in the silo at all. Ignore
	 * that for now, and return no matches when the query is actually run. */
	section->element_idx = xb_silo_get_strtab_idx(context->silo, section->element);

	return g_steal_pointer(&section);
}

/* Returns an error if the XPath is invalid. */
static gboolean
xb_query_parse(XbQuery *self, XbQueryParseContext *context, const gchar *xpath, GError **error)
{
	XbQueryPrivate *priv = GET_PRIVATE(self);
	XbQuerySection *section;
	g_autoptr(GString) acc = g_string_new(NULL);

	//	g_debug ("parsing XPath %s", xpath);
	for (gsize i = 0; xpath[i] != '\0'; i++) {
		/* escaped chars */
		if (xpath[i] == '\\') {
			if (xpath[i + 1] == '/' || xpath[i + 1] == 't' || xpath[i + 1] == 'n') {
				g_string_append_c(acc, xpath[i + 1]);
				i += 1;
				continue;
			}
		}

		/* split */
		if (xpath[i] == '/') {
			if (acc->len == 0) {
				g_set_error_literal(error,
						    G_IO_ERROR,
						    G_IO_ERROR_NOT_FOUND,
						    "xpath section empty");
				return FALSE;
			}
			section = xb_query_parse_section(self, context, acc->str, error);
			if (section == NULL)
				return FALSE;
			g_ptr_array_add(priv->sections, section);
			if (priv->sections->len > XB_QUERY_SECTION_MAX) {
				g_set_error_literal(error,
						    G_IO_ERROR,
						    G_IO_ERROR_INVALID_DATA,
						    "too many XPath sections");
				return FALSE;
			}
			g_string_truncate(acc, 0);
			continue;
		}
		g_string_append_c(acc, xpath[i]);
	}

	/* add any remaining section */
	section = xb_query_parse_section(self, context, acc->str, error);
	if (section == NULL)
		return FALSE;
	g_ptr_array_add(priv->sections, section);
	return TRUE;
}

/**
 * xb_query_new_full:
 * @silo: a #XbSilo
 * @xpath: The XPath query
 * @flags: some #XbQueryFlags, e.g. #XB_QUERY_FLAG_USE_INDEXES
 * @error: the #GError, or %NULL
 *
 * Creates a query to be used by @silo. It may be quicker to create a query
 * manually and re-use it multiple times.
 *
 * The query will point to strings inside @silo, so the lifetime of @silo must
 * exceed the lifetime of the returned query.
 *
 * Returns: (transfer full): a #XbQuery
 *
 * Since: 0.1.6
 **/
XbQuery *
xb_query_new_full(XbSilo *silo, const gchar *xpath, XbQueryFlags flags, GError **error)
{
	g_autoptr(XbQuery) self = g_object_new(XB_TYPE_QUERY, NULL);
	XbQueryPrivate *priv = GET_PRIVATE(self);
	XbQueryParseContext parse_context = {
	    .silo = silo,
	};

	g_return_val_if_fail(XB_IS_SILO(silo), NULL);
	g_return_val_if_fail(error == NULL || *error == NULL, NULL);

	/* create; don’t take a reference on @silo otherwise we get refcount
	 * loops with cached queries from xb_silo_lookup_query() */
	priv->xpath = g_strdup(xpath);
	priv->flags = flags;
	priv->sections = g_ptr_array_new_with_free_func((GDestroyNotify)xb_query_section_free);

	/* add each section */
	if (!xb_query_parse(self, &parse_context, xpath, error))
		return NULL;

	/* nothing here! */
	if (priv->sections->len == 0) {
		g_set_error(error,
			    G_IO_ERROR,
			    G_IO_ERROR_NOT_SUPPORTED,
			    "No query sections for '%s'",
			    xpath);
		return NULL;
	}

	/* success */
	return g_steal_pointer(&self);
}

/**
 * xb_query_new:
 * @silo: a #XbSilo
 * @xpath: The XPath query
 * @error: the #GError, or %NULL
 *
 * Creates a query to be used by @silo. It may be quicker to create a query
 * manually and re-use it multiple times.
 *
 * Returns: (transfer full): a #XbQuery
 *
 * Since: 0.1.4
 **/
XbQuery *
xb_query_new(XbSilo *silo, const gchar *xpath, GError **error)
{
	return xb_query_new_full(silo,
				 xpath,
				 XB_QUERY_FLAG_OPTIMIZE | XB_QUERY_FLAG_USE_INDEXES,
				 error);
}

static void
xb_query_init(XbQuery *self)
{
}

static void
xb_query_finalize(GObject *obj)
{
	XbQuery *self = XB_QUERY(obj);
	XbQueryPrivate *priv = GET_PRIVATE(self);
	g_ptr_array_unref(priv->sections);
	g_free(priv->xpath);
	G_OBJECT_CLASS(xb_query_parent_class)->finalize(obj);
}

static void
xb_query_class_init(XbQueryClass *klass)
{
	GObjectClass *object_class = G_OBJECT_CLASS(klass);
	object_class->finalize = xb_query_finalize;
}