Mercurial > defr > drupal > core
diff includes/database.inc @ 1:c1f4ac30525a 6.0
Drupal 6.0
author | Franck Deroche <webmaster@defr.org> |
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date | Tue, 23 Dec 2008 14:28:28 +0100 |
parents | |
children | fff6d4c8c043 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/includes/database.inc Tue Dec 23 14:28:28 2008 +0100 @@ -0,0 +1,583 @@ +<?php +// $Id: database.inc,v 1.92.2.1 2008/02/08 22:44:59 goba Exp $ + +/** + * @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.title, n.body, 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.title, n.body, 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_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?) + return (int) array_shift($args); // We don't need db_escape_string as numbers are db-safe + case '%s': + return db_escape_string(array_shift($args)); + 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)/'); + +/** + * 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 $query; +} + +/** + * Restrict a dynamic table, column or constraint name to safe characters. + * + * Only keeps alphanumeric and underscores. + */ +function db_escape_table($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. + * - '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 '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 key': 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': + // For 'numeric' values, we use '%s', not '\'%s\'' as with + // string types, because numeric values should not be enclosed + // in quotes in queries (though they can be, at least on mysql + // and pgsql). Numerics should only have [0-9.+-] and + // presumably no db's "escape string" function will mess with + // those characters. + return '%s'; + + 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". + */