ddl_rewriter_plugin.cc

/*  Copyright (c) 2018, 2024, Oracle and/or its affiliates.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2.0,
    as published by the Free Software Foundation.

    This program is designed to work with certain software (including
    but not limited to OpenSSL) that is licensed under separate terms,
    as designated in a particular file or component or in included license
    documentation.  The authors of MySQL hereby grant you an additional
    permission to link the program and your derivative works with the
    separately licensed software that they have either included with
    the program or referenced in the documentation.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License, version 2.0, for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include <string>

#include <ctype.h>
#include <mysql/plugin.h>
#include <mysql/plugin_audit.h>
#include <mysql/psi/mysql_memory.h>
#include <mysql/service_mysql_alloc.h>

#include "my_inttypes.h"
#include "my_psi_config.h"
#include "my_thread.h"  // my_thread_handle needed by mysql_memory.h
#include "plugin/ddl_rewriter/ddl_rewriter.h"
#include "template_utils.h"

/* Instrument the memory allocation. */
#ifdef HAVE_PSI_INTERFACE
static PSI_memory_key key_memory_ddl_rewriter;

static PSI_memory_info all_rewrite_memory[] = {
    {&key_memory_ddl_rewriter, "ddl_rewriter", 0, 0, PSI_DOCUMENT_ME}};

static int plugin_init(MYSQL_PLUGIN) {
  const char *category = "rewriter";
  int count = static_cast<int>(array_elements(all_rewrite_memory));
  mysql_memory_register(category, all_rewrite_memory, count);
  return 0; /* success */
}
#else
#define plugin_init nullptr
#define key_memory_ddl_rewriter PSI_NOT_INSTRUMENTED
#endif /* HAVE_PSI_INTERFACE */

static int rewrite_ddl(MYSQL_THD, mysql_event_class_t event_class,
                       const void *event) {
  /* We can exit early if this is not a pre-parse event. */
  const struct mysql_event_parse *event_parse =
      static_cast<const struct mysql_event_parse *>(event);
  if (event_class != MYSQL_AUDIT_PARSE_CLASS ||
      event_parse->event_subclass != MYSQL_AUDIT_PARSE_PREPARSE)
    return 0;

  /*
    If the query is rewritten, we must allocate space for the
    resulting query string and set the event flag accordingly.
  */
  std::string rewritten_query;
  if (query_rewritten(std::string(event_parse->query.str), &rewritten_query)) {
    char *rewritten_query_buf = static_cast<char *>(my_malloc(
        key_memory_ddl_rewriter, rewritten_query.length() + 1, MYF(0)));
    strcpy(rewritten_query_buf, rewritten_query.c_str());
    event_parse->rewritten_query->str = rewritten_query_buf;
    event_parse->rewritten_query->length = rewritten_query.length();
    *(reinterpret_cast<int *>(event_parse->flags)) |=
        MYSQL_AUDIT_PARSE_REWRITE_PLUGIN_QUERY_REWRITTEN;
  }

  return 0;
}

/* Audit plugin descriptor. */
static struct st_mysql_audit ddl_rewriter_descriptor = {
    MYSQL_AUDIT_INTERFACE_VERSION, /* interface version */
    nullptr,                       /* release_thd()     */
    rewrite_ddl,                   /* event_notify()    */
    {
        0,
        0,
        (unsigned long)MYSQL_AUDIT_PARSE_ALL,
    } /* class mask        */
};

/* Plugin descriptor */
mysql_declare_plugin(audit_log){
    MYSQL_AUDIT_PLUGIN,           /* plugin type             */
    &ddl_rewriter_descriptor,     /* type specific descriptor*/
    "ddl_rewriter",               /* plugin name             */
    PLUGIN_AUTHOR_ORACLE,         /* author                  */
    "Rewrite of DDL statements.", /* description             */
    PLUGIN_LICENSE_GPL,           /* license                 */
    plugin_init,                  /* plugin initializer      */
    nullptr,                      /* plugin check uninstall  */
    nullptr,                      /* plugin deinitializer    */
    0x0100,                       /* version                 */
    nullptr,                      /* status variables        */
    nullptr,                      /* system variables        */
    nullptr,                      /* reserved                */
    0                             /* flags                   */
} mysql_declare_plugin_end;