discover.cc

/* Copyright (c) 2004, 2023, 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 also distributed 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 included with MySQL.

   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,
   51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA */


/**
  @file

  @brief
  Functions for discover of frm file from handler
*/

#include "discover.h"
#include "mysqld.h"
#include "table.h"
#include <my_dir.h>
#include "my_sys.h"

#include "pfs_file_provider.h"
#include "mysql/psi/mysql_file.h"

/**
  Read the contents of a .frm file.

  frmdata and len are set to 0 on error.

  @param name           path to table-file "db/name"
  @param frmdata        frm data
  @param len            length of the read frmdata

  @retval
    0	ok
  @retval
    1	Could not open file
  @retval
    2    Could not stat file
  @retval
    3    Could not allocate data for read.  Could not read file
*/

int readfrm(const char *name, uchar **frmdata, size_t *len)
{
  int    error;
  char	 index_file[FN_REFLEN];
  File	 file;
  size_t read_len;
  uchar *read_data;
  MY_STAT state;  
  DBUG_ENTER("readfrm");
  DBUG_PRINT("enter",("name: '%s'",name));
  
  *frmdata= NULL;      // In case of errors
  *len= 0;
  error= 1;
  if ((file= mysql_file_open(key_file_frm,
                             fn_format(index_file, name, "", reg_ext,
                               MY_UNPACK_FILENAME|MY_APPEND_EXT),
                             O_RDONLY | O_SHARE,
                             MYF(0))) < 0)
    goto err_end; 
  
  // Get length of file
  error= 2;
  if (mysql_file_fstat(file, &state, MYF(0)))
    goto err;
  read_len= static_cast<size_t>(state.st_size);

  // Read whole frm file
  error= 3;
  read_data= 0;                                 // Nothing to free
  if (read_string(file, &read_data, read_len))
    goto err;

  // Setup return data
  *frmdata= read_data;
  *len= read_len;
  error= 0;
  
 err:
  if (file > 0)
    (void) mysql_file_close(file, MYF(MY_WME));
  
 err_end:		      /* Here when no file */
  DBUG_RETURN (error);
} /* readfrm */


/*
  Write the content of a frm data pointer 
  to a frm file.

  @param name           path to table-file "db/name"
  @param frmdata        frm data
  @param len            length of the frmdata

  @retval
    0	ok
  @retval
    2    Could not write file
*/

int writefrm(const char *name, const uchar *frmdata, size_t len)
{
  File file;
  char	 index_file[FN_REFLEN];
  int error;
  DBUG_ENTER("writefrm");
  DBUG_PRINT("enter",("name: '%s' len: %lu ",name, (ulong) len));

  error= 0;
  if ((file= mysql_file_create(key_file_frm,
                               fn_format(index_file, name, "", reg_ext,
                                         MY_UNPACK_FILENAME | MY_APPEND_EXT),
                               CREATE_MODE, O_RDWR | O_TRUNC,
                               MYF(MY_WME))) >= 0)
  {
    if (mysql_file_write(file, frmdata, len, MYF(MY_WME | MY_NABP)))
      error= 2;
    (void) mysql_file_close(file, MYF(0));
  }
  DBUG_RETURN(error);
} /* writefrm */