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<?php
/**
* @file
* Wrapper for database interface code.
*/
/**
* A hash value to check when outputting database errors, md5('DB_ERROR').
*
* @see drupal_error_handler()
*/
define('DB_ERROR', 'a515ac9c2796ca0e23adbe92c68fc9fc');
/**
* @defgroup database Database abstraction layer
* @{
* Allow the use of different database servers using the same code base.
*
* Drupal provides a slim database abstraction layer to provide developers with
* the ability to support multiple database servers easily. The intent of this
* layer is to preserve the syntax and power of SQL as much as possible, while
* letting Drupal control the pieces of queries that need to be written
* differently for different servers and provide basic security checks.
*
* Most Drupal database queries are performed by a call to db_query() or
* db_query_range(). Module authors should also consider using pager_query() for
* queries that return results that need to be presented on multiple pages, and
* tablesort_sql() for generating appropriate queries for sortable tables.
*
* For example, one might wish to return a list of the most recent 10 nodes
* authored by a given user. Instead of directly issuing the SQL query
* @code
* SELECT n.nid, n.title, n.created FROM node n WHERE n.uid = $uid LIMIT 0, 10;
* @endcode
* one would instead call the Drupal functions:
* @code
* $result = db_query_range('SELECT n.nid, n.title, n.created
* FROM {node} n WHERE n.uid = %d', $uid, 0, 10);
* while ($node = db_fetch_object($result)) {
* // Perform operations on $node->body, etc. here.
* }
* @endcode
* Curly braces are used around "node" to provide table prefixing via
* db_prefix_tables(). The explicit use of a user ID is pulled out into an
* argument passed to db_query() so that SQL injection attacks from user input
* can be caught and nullified. The LIMIT syntax varies between database servers,
* so that is abstracted into db_query_range() arguments. Finally, note the
* common pattern of iterating over the result set using db_fetch_object().
*/
/**
* Perform an SQL query and return success or failure.
*
* @param $sql
* A string containing a complete SQL query. %-substitution
* parameters are not supported.
* @return
* An array containing the keys:
* success: a boolean indicating whether the query succeeded
* query: the SQL query executed, passed through check_plain()
*/
function update_sql($sql) {
$result = db_query($sql, true);
return array('success' => $result !== FALSE, 'query' => check_plain($sql));
}
/**
* Append a database prefix to all tables in a query.
*
* Queries sent to Drupal should wrap all table names in curly brackets. This
* function searches for this syntax and adds Drupal's table prefix to all
* tables, allowing Drupal to coexist with other systems in the same database if
* necessary.
*
* @param $sql
* A string containing a partial or entire SQL query.
* @return
* The properly-prefixed string.
*/
function db_prefix_tables($sql) {
global $db_prefix;
if (is_array($db_prefix)) {
if (array_key_exists('default', $db_prefix)) {
$tmp = $db_prefix;
unset($tmp['default']);
foreach ($tmp as $key => $val) {
$sql = strtr($sql, array('{'. $key .'}' => $val . $key));
}
return strtr($sql, array('{' => $db_prefix['default'], '}' => ''));
}
else {
foreach ($db_prefix as $key => $val) {
$sql = strtr($sql, array('{'. $key .'}' => $val . $key));
}
return strtr($sql, array('{' => '', '}' => ''));
}
}
else {
return strtr($sql, array('{' => $db_prefix, '}' => ''));
}
}
/**
* Activate a database for future queries.
*
* If it is necessary to use external databases in a project, this function can
* be used to change where database queries are sent. If the database has not
* yet been used, it is initialized using the URL specified for that name in
* Drupal's configuration file. If this name is not defined, a duplicate of the
* default connection is made instead.
*
* Be sure to change the connection back to the default when done with custom
* code.
*
* @param $name
* The name assigned to the newly active database connection. If omitted, the
* default connection will be made active.
*
* @return the name of the previously active database or FALSE if non was found.
*/
function db_set_active($name = 'default') {
global $db_url, $db_type, $active_db;
static $db_conns, $active_name = FALSE;
if (empty($db_url)) {
include_once 'includes/install.inc';
install_goto('install.php');
}
if (!isset($db_conns[$name])) {
// Initiate a new connection, using the named DB URL specified.
if (is_array($db_url)) {
$connect_url = array_key_exists($name, $db_url) ? $db_url[$name] : $db_url['default'];
}
else {
$connect_url = $db_url;
}
$db_type = substr($connect_url, 0, strpos($connect_url, '://'));
$handler = "./includes/database.$db_type.inc";
if (is_file($handler)) {
include_once $handler;
}
else {
_db_error_page("The database type '". $db_type ."' is unsupported. Please use either 'mysql' or 'mysqli' for MySQL, or 'pgsql' for PostgreSQL databases.");
}
$db_conns[$name] = db_connect($connect_url);
}
$previous_name = $active_name;
// Set the active connection.
$active_name = $name;
$active_db = $db_conns[$name];
return $previous_name;
}
/**
* Helper function to show fatal database errors.
*
* Prints a themed maintenance page with the 'Site off-line' text,
* adding the provided error message in the case of 'display_errors'
* set to on. Ends the page request; no return.
*
* @param $error
* The error message to be appended if 'display_errors' is on.
*/
function _db_error_page($error = '') {
global $db_type;
drupal_init_language();
drupal_maintenance_theme();
drupal_set_header('HTTP/1.1 503 Service Unavailable');
drupal_set_title('Site off-line');
$message = '<p>The site is currently not available due to technical problems. Please try again later. Thank you for your understanding.</p>';
$message .= '<hr /><p><small>If you are the maintainer of this site, please check your database settings in the <code>settings.php</code> file and ensure that your hosting provider\'s database server is running. For more help, see the <a href="http://drupal.org/node/258">handbook</a>, or contact your hosting provider.</small></p>';
if ($error && ini_get('display_errors')) {
$message .= '<p><small>The '. theme('placeholder', $db_type) .' error was: '. theme('placeholder', $error) .'.</small></p>';
}
print theme('maintenance_page', $message);
exit;
}
/**
* Returns a boolean depending on the availability of the database.
*/
function db_is_active() {
global $active_db;
return !empty($active_db);
}
/**
* Helper function for db_query().
*/
function _db_query_callback($match, $init = FALSE) {
static $args = NULL;
if ($init) {
$args = $match;
return;
}
switch ($match[1]) {
case '%d': // We must use type casting to int to convert FALSE/NULL/(TRUE?)
$value = array_shift($args);
// Do we need special bigint handling?
if ($value > PHP_INT_MAX) {
$precision = ini_get('precision');
@ini_set('precision', 16);
$value = sprintf('%.0f', $value);
@ini_set('precision', $precision);
}
else {
$value = (int) $value;
}
// We don't need db_escape_string as numbers are db-safe.
return $value;
case '%s':
return db_escape_string(array_shift($args));
case '%n':
// Numeric values have arbitrary precision, so can't be treated as float.
// is_numeric() allows hex values (0xFF), but they are not valid.
$value = trim(array_shift($args));
return is_numeric($value) && !preg_match('/x/i', $value) ? $value : '0';
case '%%':
return '%';
case '%f':
return (float) array_shift($args);
case '%b': // binary data
return db_encode_blob(array_shift($args));
}
}
/**
* Generate placeholders for an array of query arguments of a single type.
*
* Given a Schema API field type, return correct %-placeholders to
* embed in a query
*
* @param $arguments
* An array with at least one element.
* @param $type
* The Schema API type of a field (e.g. 'int', 'text', or 'varchar').
*/
function db_placeholders($arguments, $type = 'int') {
$placeholder = db_type_placeholder($type);
return implode(',', array_fill(0, count($arguments), $placeholder));
}
/**
* Indicates the place holders that should be replaced in _db_query_callback().
*/
define('DB_QUERY_REGEXP', '/(%d|%s|%%|%f|%b|%n)/');
/**
* Helper function for db_rewrite_sql.
*
* Collects JOIN and WHERE statements via hook_db_rewrite_sql()
* Decides whether to select primary_key or DISTINCT(primary_key)
*
* @param $query
* Query to be rewritten.
* @param $primary_table
* Name or alias of the table which has the primary key field for this query.
* Typical table names would be: {blocks}, {comments}, {forum}, {node},
* {menu}, {term_data} or {vocabulary}. However, in most cases the usual
* table alias (b, c, f, n, m, t or v) is used instead of the table name.
* @param $primary_field
* Name of the primary field.
* @param $args
* Array of additional arguments.
* @return
* An array: join statements, where statements, field or DISTINCT(field).
*/
function _db_rewrite_sql($query = '', $primary_table = 'n', $primary_field = 'nid', $args = array()) {
$where = array();
$join = array();
$distinct = FALSE;
foreach (module_implements('db_rewrite_sql') as $module) {
$result = module_invoke($module, 'db_rewrite_sql', $query, $primary_table, $primary_field, $args);
if (isset($result) && is_array($result)) {
if (isset($result['where'])) {
$where[] = $result['where'];
}
if (isset($result['join'])) {
$join[] = $result['join'];
}
if (isset($result['distinct']) && $result['distinct']) {
$distinct = TRUE;
}
}
elseif (isset($result)) {
$where[] = $result;
}
}
$where = empty($where) ? '' : '('. implode(') AND (', $where) .')';
$join = empty($join) ? '' : implode(' ', $join);
return array($join, $where, $distinct);
}
/**
* Rewrites node, taxonomy and comment queries. Use it for listing queries. Do not
* use FROM table1, table2 syntax, use JOIN instead.
*
* @param $query
* Query to be rewritten.
* @param $primary_table
* Name or alias of the table which has the primary key field for this query.
* Typical table names would be: {blocks}, {comments}, {forum}, {node},
* {menu}, {term_data} or {vocabulary}. However, it is more common to use the
* the usual table aliases: b, c, f, n, m, t or v.
* @param $primary_field
* Name of the primary field.
* @param $args
* An array of arguments, passed to the implementations of hook_db_rewrite_sql.
* @return
* The original query with JOIN and WHERE statements inserted from
* hook_db_rewrite_sql implementations. nid is rewritten if needed.
*/
function db_rewrite_sql($query, $primary_table = 'n', $primary_field = 'nid', $args = array()) {
list($join, $where, $distinct) = _db_rewrite_sql($query, $primary_table, $primary_field, $args);
if ($distinct) {
$query = db_distinct_field($primary_table, $primary_field, $query);
}
if (!empty($where) || !empty($join)) {
$pattern = '{
# Beginning of the string
^
((?P<anonymous_view>
# Everything within this set of parentheses is named "anonymous view"
(?:
[^()]++ # anything not parentheses
|
\( (?P>anonymous_view) \) # an open parenthesis, more "anonymous view" and finally a close parenthesis.
)*
)[^()]+WHERE)
}x';
preg_match($pattern, $query, $matches);
if (!$where) {
$where = '1 = 1';
}
if ($matches) {
$n = strlen($matches[1]);
$second_part = substr($query, $n);
$first_part = substr($matches[1], 0, $n - 5) ." $join WHERE $where AND ( ";
// PHP 4 does not support strrpos for strings. We emulate it.
$haystack_reverse = strrev($second_part);
}
else {
$haystack_reverse = strrev($query);
}
// No need to use strrev on the needle, we supply GROUP, ORDER, LIMIT
// reversed.
foreach (array('PUORG', 'REDRO', 'TIMIL') as $needle_reverse) {
$pos = strpos($haystack_reverse, $needle_reverse);
if ($pos !== FALSE) {
// All needles are five characters long.
$pos += 5;
break;
}
}
if ($matches) {
if ($pos === FALSE) {
$query = $first_part . $second_part .')';
}
else {
$query = $first_part . substr($second_part, 0, -$pos) .')'. substr($second_part, -$pos);
}
}
elseif ($pos === FALSE) {
$query .= " $join WHERE $where";
}
else {
$query = substr($query, 0, -$pos) . " $join WHERE $where " . substr($query, -$pos);
}
}
return $query;
}
/**
* Adds the DISTINCT flag to the supplied query and returns the altered query.
*
* The supplied query should not contain a DISTINCT flag. This will not, and
* never did guarantee that you will obtain distinct values of $table.$field.
*
* @param $table
* Unused. Kept to retain API compatibility.
* @param $field
* Unused. Kept to retain API compatibility.
* @param $query
* Query to which the DISTINCT flag should be applied.
*
* @return
* SQL query with the DISTINCT flag set.
*/
function db_distinct_field($table, $field, $query) {
$matches = array();
if (!preg_match('/^SELECT\s*DISTINCT/i', $query, $matches)) {
// Only add distinct to the outer SELECT to avoid messing up subqueries.
$query = preg_replace('/^SELECT/i', 'SELECT DISTINCT', $query);
}
return $query;
}
/**
* Restrict a dynamic table, column or constraint name to safe characters.
*
* Only keeps alphanumeric and underscores.
*/
function db_escape_table($string) {
return preg_replace('/[^A-Za-z0-9_]+/', '', $string);
}
/**
* @} End of "defgroup database".
*/
/**
* @defgroup schemaapi Schema API
* @{
*
* A Drupal schema definition is an array structure representing one or
* more tables and their related keys and indexes. A schema is defined by
* hook_schema(), which usually lives in a modulename.install file.
*
* By implementing hook_schema() and specifying the tables your module
* declares, you can easily create and drop these tables on all
* supported database engines. You don't have to deal with the
* different SQL dialects for table creation and alteration of the
* supported database engines.
*
* hook_schema() should return an array with a key for each table that
* the module defines.
*
* The following keys are defined:
*
* - 'description': A string describing this table and its purpose.
* References to other tables should be enclosed in
* curly-brackets. For example, the node_revisions table
* description field might contain "Stores per-revision title and
* body data for each {node}."
* - 'fields': An associative array ('fieldname' => specification)
* that describes the table's database columns. The specification
* is also an array. The following specification parameters are defined:
* - 'description': A string describing this field and its purpose.
* References to other tables should be enclosed in
* curly-brackets. For example, the node table vid field
* description might contain "Always holds the largest (most
* recent) {node_revisions}.vid value for this nid."
* - 'type': The generic datatype: 'varchar', 'int', 'serial'
* 'float', 'numeric', 'text', 'blob' or 'datetime'. Most types
* just map to the according database engine specific
* datatypes. Use 'serial' for auto incrementing fields. This
* will expand to 'int auto_increment' on mysql.
* - 'serialize': A boolean indicating whether the field will be stored
as a serialized string.
* - 'size': The data size: 'tiny', 'small', 'medium', 'normal',
* 'big'. This is a hint about the largest value the field will
* store and determines which of the database engine specific
* datatypes will be used (e.g. on MySQL, TINYINT vs. INT vs. BIGINT).
* 'normal', the default, selects the base type (e.g. on MySQL,
* INT, VARCHAR, BLOB, etc.).
* Not all sizes are available for all data types. See
* db_type_map() for possible combinations.
* - 'not null': If true, no NULL values will be allowed in this
* database column. Defaults to false.
* - 'default': The field's default value. The PHP type of the
* value matters: '', '0', and 0 are all different. If you
* specify '0' as the default value for a type 'int' field it
* will not work because '0' is a string containing the
* character "zero", not an integer.
* - 'length': The maximal length of a type 'char', 'varchar' or 'text'
* field. Ignored for other field types.
* - 'unsigned': A boolean indicating whether a type 'int', 'float'
* and 'numeric' only is signed or unsigned. Defaults to
* FALSE. Ignored for other field types.
* - 'precision', 'scale': For type 'numeric' fields, indicates
* the precision (total number of significant digits) and scale
* (decimal digits right of the decimal point). Both values are
* mandatory. Ignored for other field types.
* All parameters apart from 'type' are optional except that type
* 'numeric' columns must specify 'precision' and 'scale'.
* - 'primary key': An array of one or more key column specifiers (see below)
* that form the primary key.
* - 'unique keys': An associative array of unique keys ('keyname' =>
* specification). Each specification is an array of one or more
* key column specifiers (see below) that form a unique key on the table.
* - 'indexes': An associative array of indexes ('indexame' =>
* specification). Each specification is an array of one or more
* key column specifiers (see below) that form an index on the
* table.
*
* A key column specifier is either a string naming a column or an
* array of two elements, column name and length, specifying a prefix
* of the named column.
*
* As an example, here is a SUBSET of the schema definition for
* Drupal's 'node' table. It show four fields (nid, vid, type, and
* title), the primary key on field 'nid', a unique key named 'vid' on
* field 'vid', and two indexes, one named 'nid' on field 'nid' and
* one named 'node_title_type' on the field 'title' and the first four
* bytes of the field 'type':
*
* @code
* $schema['node'] = array(
* 'fields' => array(
* 'nid' => array('type' => 'serial', 'unsigned' => TRUE, 'not null' => TRUE),
* 'vid' => array('type' => 'int', 'unsigned' => TRUE, 'not null' => TRUE, 'default' => 0),
* 'type' => array('type' => 'varchar', 'length' => 32, 'not null' => TRUE, 'default' => ''),
* 'title' => array('type' => 'varchar', 'length' => 128, 'not null' => TRUE, 'default' => ''),
* ),
* 'primary key' => array('nid'),
* 'unique keys' => array(
* 'vid' => array('vid')
* ),
* 'indexes' => array(
* 'nid' => array('nid'),
* 'node_title_type' => array('title', array('type', 4)),
* ),
* );
* @endcode
*
* @see drupal_install_schema()
*/
/**
* Create a new table from a Drupal table definition.
*
* @param $ret
* Array to which query results will be added.
* @param $name
* The name of the table to create.
* @param $table
* A Schema API table definition array.
*/
function db_create_table(&$ret, $name, $table) {
$statements = db_create_table_sql($name, $table);
foreach ($statements as $statement) {
$ret[] = update_sql($statement);
}
}
/**
* Return an array of field names from an array of key/index column specifiers.
*
* This is usually an identity function but if a key/index uses a column prefix
* specification, this function extracts just the name.
*
* @param $fields
* An array of key/index column specifiers.
* @return
* An array of field names.
*/
function db_field_names($fields) {
$ret = array();
foreach ($fields as $field) {
if (is_array($field)) {
$ret[] = $field[0];
}
else {
$ret[] = $field;
}
}
return $ret;
}
/**
* Given a Schema API field type, return the correct %-placeholder.
*
* Embed the placeholder in a query to be passed to db_query and and pass as an
* argument to db_query a value of the specified type.
*
* @param $type
* The Schema API type of a field.
* @return
* The placeholder string to embed in a query for that type.
*/
function db_type_placeholder($type) {
switch ($type) {
case 'varchar':
case 'char':
case 'text':
case 'datetime':
return "'%s'";
case 'numeric':
// Numeric values are arbitrary precision numbers. Syntacically, numerics
// should be specified directly in SQL. However, without single quotes
// the %s placeholder does not protect against non-numeric characters such
// as spaces which would expose us to SQL injection.
return '%n';
case 'serial':
case 'int':
return '%d';
case 'float':
return '%f';
case 'blob':
return '%b';
}
// There is no safe value to return here, so return something that
// will cause the query to fail.
return 'unsupported type '. $type .'for db_type_placeholder';
}
/**
* @} End of "defgroup schemaapi".
*/