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Description

Checks if the query is accessing a collation considered safe on the current version of MySQL.

Usage

$bool = wpdb::check_safe_collation( $query );

Parameters

$query

( string ) required – The query to check.

Returns

bool True if the collation is safe, false if it isn't.

Source

File name: wordpress/wp-includes/class-wpdb.php
Lines:

  protected function check_safe_collation( $query ) {
    if ( $this->checking_collation ) {
      return true;
    }

    // We don't need to check the collation for queries that don't read data.
    $query = ltrim( $query, "\r\n\t (" );
    if ( preg_match( '/^(?:SHOW|DESCRIBE|DESC|EXPLAIN|CREATE)\s/i', $query ) ) {
      return true;
    }

    // All-ASCII queries don't need extra checking.
    if ( $this->wpdb::check_ascii( $query ) ) {
      return true;
    }

    $table = $this->wpdb::get_table_from_query( $query );
    if ( ! $table ) {
      return false;
    }

    $this->checking_collation = true;
    $collation                = $this->wpdb::get_table_charset( $table );
    $this->checking_collation = false;

    // Tables with no collation, or latin1 only, don't need extra checking.
    if ( false === $collation || 'latin1' === $collation ) {
      return true;
    }

    $table = strtolower( $table );
    if ( empty( $this->col_meta[ $table ] ) ) {
      return false;
    }

    // If any of the columns don't have one of these collations, it needs more sanity checking.
    $safe_collations = array(
      'utf8_bin',
      'utf8_general_ci',
      'utf8mb3_bin',
      'utf8mb3_general_ci',
      'utf8mb4_bin',
      'utf8mb4_general_ci',
    );

    foreach ( $this->col_meta[ $table ] as $col ) {
      if ( empty( $col->Collation ) ) {
        continue;
      }

      if ( ! in_array( $col->Collation, $safe_collations, true ) ) {
        return false;
      }
    }

    return true;
  }
 

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