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| 1 | <?php |
| 2 | /** |
| 3 | * This program is free software; you can redistribute it and/or modify |
| 4 | * it under the terms of the GNU General Public License as published by |
| 5 | * the Free Software Foundation; either version 2 of the License, or |
| 6 | * (at your option) any later version. |
| 7 | * |
| 8 | * This program is distributed in the hope that it will be useful, |
| 9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 11 | * GNU General Public License for more details. |
| 12 | * |
| 13 | * You should have received a copy of the GNU General Public License along |
| 14 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 15 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| 16 | * http://www.gnu.org/copyleft/gpl.html |
| 17 | * |
| 18 | * @file |
| 19 | */ |
| 20 | namespace Wikimedia\Rdbms; |
| 21 | |
| 22 | use Wikimedia\Rdbms\Platform\SQLPlatform; |
| 23 | |
| 24 | /** |
| 25 | * This is to contain any regex on SQL work and get rid of them eventually |
| 26 | * |
| 27 | * This is a radioactive swamp and an extremely flawed and buggy last resort |
| 28 | * for when the information has not been provided via Query object. |
| 29 | * Bugs are to be expected in the regexes here. |
| 30 | * |
| 31 | * @ingroup Database |
| 32 | * @internal |
| 33 | * @since 1.41 |
| 34 | */ |
| 35 | class QueryBuilderFromRawSql { |
| 36 | /** All the bits of QUERY_WRITE_* flags */ |
| 37 | private const QUERY_CHANGE_MASK = ( |
| 38 | SQLPlatform::QUERY_CHANGE_NONE | |
| 39 | SQLPlatform::QUERY_CHANGE_TRX | |
| 40 | SQLPlatform::QUERY_CHANGE_ROWS | |
| 41 | SQLPlatform::QUERY_CHANGE_SCHEMA | |
| 42 | SQLPlatform::QUERY_CHANGE_LOCKS |
| 43 | ) & ~SQLPlatform::QUERY_IGNORE_DBO_TRX; |
| 44 | |
| 45 | private const SCHEMA_CHANGE_VERBS = [ |
| 46 | 'CREATE', |
| 47 | 'CREATE TEMPORARY', |
| 48 | 'CREATE INDEX', |
| 49 | 'CREATE DATABASE', |
| 50 | 'ALTER', |
| 51 | 'ALTER DATABASE', |
| 52 | 'DROP', |
| 53 | 'DROP INDEX', |
| 54 | 'DROP DATABASE', |
| 55 | ]; |
| 56 | |
| 57 | private const TRX_VERBS = [ |
| 58 | 'BEGIN', |
| 59 | 'COMMIT', |
| 60 | 'ROLLBACK', |
| 61 | 'SAVEPOINT', |
| 62 | 'RELEASE SAVEPOINT', |
| 63 | 'ROLLBACK TO SAVEPOINT', |
| 64 | ]; |
| 65 | |
| 66 | private static string $queryVerbRegex; |
| 67 | |
| 68 | /** |
| 69 | * @param string $sql |
| 70 | * @param int $flags |
| 71 | * @param string $tablePrefix |
| 72 | * @return Query |
| 73 | */ |
| 74 | public static function buildQuery( string $sql, $flags, string $tablePrefix = '' ) { |
| 75 | $verb = self::getQueryVerb( $sql ); |
| 76 | |
| 77 | if ( ( $flags & self::QUERY_CHANGE_MASK ) == 0 ) { |
| 78 | $isWriteQuery = self::isWriteQuery( $sql ); |
| 79 | if ( $isWriteQuery ) { |
| 80 | if ( in_array( $verb, self::SCHEMA_CHANGE_VERBS, true ) ) { |
| 81 | $flags |= SQLPlatform::QUERY_CHANGE_SCHEMA; |
| 82 | } else { |
| 83 | $flags |= SQLPlatform::QUERY_CHANGE_ROWS; |
| 84 | } |
| 85 | } else { |
| 86 | if ( in_array( $verb, self::TRX_VERBS, true ) ) { |
| 87 | $flags |= SQLPlatform::QUERY_CHANGE_TRX; |
| 88 | } else { |
| 89 | $flags |= SQLPlatform::QUERY_CHANGE_NONE; |
| 90 | } |
| 91 | } |
| 92 | } |
| 93 | |
| 94 | return new Query( |
| 95 | $sql, |
| 96 | $flags, |
| 97 | $verb, |
| 98 | self::getWriteTable( $sql, $tablePrefix ) |
| 99 | ); |
| 100 | } |
| 101 | |
| 102 | private static function isWriteQuery( $rawSql ) { |
| 103 | // Treat SELECT queries without FOR UPDATE queries as non-writes. This matches |
| 104 | // how MySQL enforces read_only (FOR SHARE and LOCK IN SHADE MODE are allowed). |
| 105 | // Handle (SELECT ...) UNION (SELECT ...) queries in a similar fashion. |
| 106 | if ( preg_match( '/^\s*\(?SELECT\b/i', $rawSql ) ) { |
| 107 | return (bool)preg_match( '/\bFOR\s+UPDATE\)?\s*$/i', $rawSql ); |
| 108 | } |
| 109 | // BEGIN and COMMIT queries are considered non-write queries here. |
| 110 | // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally |
| 111 | // treat these as write queries, in that their results have "affected rows" |
| 112 | // as meta data as from writes, instead of "num rows" as from reads. |
| 113 | // But, we treat them as non-write queries because when reading data (from |
| 114 | // either replica or primary DB) we use transactions to enable repeatable-read |
| 115 | // snapshots, which ensures we get consistent results from the same snapshot |
| 116 | // for all queries within a request. Use cases: |
| 117 | // - Treating these as writes would trigger ChronologyProtector (see method doc). |
| 118 | // - We use this method to reject writes to replicas, but we need to allow |
| 119 | // use of transactions on replicas for read snapshots. This is fine given |
| 120 | // that transactions by themselves don't make changes, only actual writes |
| 121 | // within the transaction matter, which we still detect. |
| 122 | return !preg_match( |
| 123 | '/^\s*(BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|USE)\b/i', |
| 124 | $rawSql |
| 125 | ); |
| 126 | } |
| 127 | |
| 128 | /** |
| 129 | * @param string $sql SQL query |
| 130 | * @return string |
| 131 | */ |
| 132 | private static function getQueryVerb( $sql ) { |
| 133 | // @phan-suppress-next-line PhanRedundantCondition https://github.com/phan/phan/issues/4720 |
| 134 | if ( !isset( self::$queryVerbRegex ) ) { |
| 135 | $multiwordVerbsRegex = implode( '|', array_map( |
| 136 | fn ( $words ) => str_replace( ' ', '\s+', $words ), |
| 137 | Query::MULTIWORD_VERBS |
| 138 | ) ); |
| 139 | self::$queryVerbRegex = "/^\s*($multiwordVerbsRegex|[a-z]+)/i"; |
| 140 | } |
| 141 | return preg_match( self::$queryVerbRegex, $sql, $m ) ? strtoupper( $m[1] ) : ''; |
| 142 | } |
| 143 | |
| 144 | /** |
| 145 | * @param string $sql |
| 146 | * @param string $tablePrefix |
| 147 | * @return string|null |
| 148 | */ |
| 149 | private static function getWriteTable( $sql, $tablePrefix ) { |
| 150 | // Regex for basic queries that can create/change/drop temporary tables. |
| 151 | // For simplicity, this only looks for tables with sensible alphanumeric names. |
| 152 | // Temporary tables only need simple programming names anyway. |
| 153 | $regex = <<<REGEX |
| 154 | /^ |
| 155 | (?: |
| 156 | (?:INSERT|REPLACE)\s+(?:\w+\s+)*?INTO |
| 157 | | UPDATE(?:\s+OR\s+\w+|\s+IGNORE|\s+ONLY)? |
| 158 | | DELETE\s+(?:\w+\s+)*?FROM(?:\s+ONLY)? |
| 159 | | CREATE\s+(?:TEMPORARY\s+)?TABLE(?:\s+IF\s+NOT\s+EXISTS)? |
| 160 | | DROP\s+(?:TEMPORARY\s+)?TABLE(?:\s+IF\s+EXISTS)? |
| 161 | | TRUNCATE\s+(?:TEMPORARY\s+)?TABLE |
| 162 | | ALTER\s+TABLE |
| 163 | ) \s+ |
| 164 | (\w+|`\w+`|'\w+'|"\w+") |
| 165 | /ix |
| 166 | REGEX; |
| 167 | if ( preg_match( $regex, $sql, $m ) ) { |
| 168 | $tableName = trim( $m[1], "\"'`" ); |
| 169 | if ( str_starts_with( $tableName, $tablePrefix ) ) { |
| 170 | $tableName = substr( $tableName, strlen( $tablePrefix ) ); |
| 171 | } |
| 172 | return $tableName; |
| 173 | } |
| 174 | return null; |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | * Removes most variables from an SQL query and replaces them with X or N for numbers. |
| 179 | * It's only slightly flawed. Don't use for anything important. |
| 180 | * |
| 181 | * @param string $sql A SQL Query |
| 182 | * |
| 183 | * @return string |
| 184 | */ |
| 185 | public static function generalizeSQL( $sql ) { |
| 186 | # This does the same as the regexp below would do, but in such a way |
| 187 | # as to avoid crashing php on some large strings. |
| 188 | # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql ); |
| 189 | |
| 190 | $sql = str_replace( "\\\\", '', $sql ); |
| 191 | $sql = str_replace( "\\'", '', $sql ); |
| 192 | $sql = str_replace( "\\\"", '', $sql ); |
| 193 | $sql = preg_replace( "/'.*'/s", "'X'", $sql ); |
| 194 | $sql = preg_replace( '/".*"/s', "'X'", $sql ); |
| 195 | |
| 196 | # All newlines, tabs, etc replaced by single space |
| 197 | $sql = preg_replace( '/\s+/', ' ', $sql ); |
| 198 | |
| 199 | # All numbers => N, |
| 200 | # except the ones surrounded by characters, e.g. l10n |
| 201 | $sql = preg_replace( '/-?\d+(,-?\d+)+/', 'N,...,N', $sql ); |
| 202 | $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/', 'N', $sql ); |
| 203 | |
| 204 | return $sql; |
| 205 | } |
| 206 | } |