mi_page.cc

/* Copyright (c) 2000, 2025, 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 */

/* Read and write key blocks */

#include <fcntl.h>
#include <sys/types.h>
#include <cerrno>

#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_io.h"
#include "storage/myisam/myisamdef.h"

/* Fetch a key-page in memory */

uchar *_mi_fetch_keypage(MI_INFO *info, MI_KEYDEF *keyinfo, my_off_t page,
                         int level, uchar *buff, int return_buffer) {
  uchar *tmp;
  uint page_size;
  DBUG_TRACE;
  DBUG_PRINT("enter", ("page: %ld", (long)page));

  tmp = (uchar *)key_cache_read(info->s->key_cache, keycache_thread_var(),
                                info->s->kfile, page, level, (uchar *)buff,
                                (uint)keyinfo->block_length,
                                (uint)keyinfo->block_length, return_buffer);
  if (tmp == info->buff)
    info->buff_used = true;
  else if (!tmp) {
    DBUG_PRINT("error", ("Got errno: %d from key_cache_read", my_errno()));
    info->last_keypage = HA_OFFSET_ERROR;
    mi_print_error(info->s, HA_ERR_CRASHED);
    set_my_errno(HA_ERR_CRASHED);
    return nullptr;
  }
  info->last_keypage = page;
  page_size = mi_getint(tmp);
  if (page_size < 4 || page_size > keyinfo->block_length) {
    DBUG_PRINT("error",
               ("page %lu had wrong page length: %u", (ulong)page, page_size));
    DBUG_DUMP("page", tmp, keyinfo->block_length);
    info->last_keypage = HA_OFFSET_ERROR;
    mi_print_error(info->s, HA_ERR_CRASHED);
    set_my_errno(HA_ERR_CRASHED);
    tmp = nullptr;
  }
  return tmp;
} /* _mi_fetch_keypage */

/* Write a key-page on disk */

int _mi_write_keypage(MI_INFO *info, MI_KEYDEF *keyinfo, my_off_t page,
                      int level, uchar *buff) {
  uint length;
  DBUG_TRACE;

  if (page < info->s->base.keystart ||
      page + keyinfo->block_length > info->state->key_file_length ||
      (page & (MI_MIN_KEY_BLOCK_LENGTH - 1))) {
    DBUG_PRINT("error", ("Trying to write inside key status region: key_start: "
                         "%lu  length: %lu  page: %lu",
                         (long)info->s->base.keystart,
                         (long)info->state->key_file_length, (long)page));
    set_my_errno(EINVAL);
    return (-1);
  }
  DBUG_PRINT("page", ("write page at: %lu", (long)page));
  DBUG_DUMP("buff", (uchar *)buff, mi_getint(buff));

  if ((length = keyinfo->block_length) > IO_SIZE * 2 &&
      info->state->key_file_length != page + length)
    length = ((mi_getint(buff) + IO_SIZE - 1) & (uint) ~(IO_SIZE - 1));
  return (key_cache_write(
      info->s->key_cache, keycache_thread_var(), info->s->kfile, page, level,
      (uchar *)buff, length, (uint)keyinfo->block_length,
      (int)((info->lock_type != F_UNLCK) || info->s->delay_key_write)));
} /* mi_write_keypage */

/* Remove page from disk */

int _mi_dispose(MI_INFO *info, MI_KEYDEF *keyinfo, my_off_t pos, int level) {
  my_off_t old_link;
  uchar buff[8];
  DBUG_TRACE;
  DBUG_PRINT("enter", ("pos: %ld", (long)pos));

  old_link = info->s->state.key_del[keyinfo->block_size_index];
  info->s->state.key_del[keyinfo->block_size_index] = pos;
  mi_sizestore(buff, old_link);
  info->s->state.changed |= STATE_NOT_SORTED_PAGES;
  return key_cache_write(info->s->key_cache, keycache_thread_var(),
                         info->s->kfile, pos, level, buff, sizeof(buff),
                         (uint)keyinfo->block_length,
                         (int)(info->lock_type != F_UNLCK));
} /* _mi_dispose */

/* Make new page on disk */

my_off_t _mi_new(MI_INFO *info, MI_KEYDEF *keyinfo, int level) {
  my_off_t pos;
  uchar buff[8];
  DBUG_TRACE;

  if ((pos = info->s->state.key_del[keyinfo->block_size_index]) ==
      HA_OFFSET_ERROR) {
    if (info->state->key_file_length >=
        info->s->base.max_key_file_length - keyinfo->block_length) {
      set_my_errno(HA_ERR_INDEX_FILE_FULL);
      return HA_OFFSET_ERROR;
    }
    pos = info->state->key_file_length;
    info->state->key_file_length += keyinfo->block_length;
  } else {
    if (!key_cache_read(info->s->key_cache, keycache_thread_var(),
                        info->s->kfile, pos, level, buff, (uint)sizeof(buff),
                        (uint)keyinfo->block_length, 0))
      pos = HA_OFFSET_ERROR;
    else
      info->s->state.key_del[keyinfo->block_size_index] = mi_sizekorr(buff);
  }
  info->s->state.changed |= STATE_NOT_SORTED_PAGES;
  DBUG_PRINT("exit", ("Pos: %ld", (long)pos));
  return pos;
} /* _mi_new */