~drizzle-trunk/drizzle/development

/* Copyright (C) 2000 MySQL AB

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; version 2 of the License.

   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 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/*

  Advanced symlink handling.

  This is used in MyISAM to let users symlinks tables to different disk.

  The main idea with these functions is to automaticly create, delete and

  rename files and symlinks like they would be one unit.

*/

#include "mysys/mysys_priv.h"

#include "mysys/mysys_err.h"

#include <mystrings/m_string.h>

File my_create_with_symlink(const char *linkname, const char *filename,

			    int createflags, int access_flags, myf MyFlags)

{

  File file;

  int tmp_errno;

  /* Test if we should create a link */

  int create_link;

  char abs_linkname[FN_REFLEN];

  char rp_buff[PATH_MAX];

  if (my_disable_symlinks)

  {

    /* Create only the file, not the link and file */

    create_link= 0;

    if (linkname)

      filename= linkname;

  }

  else

  {

    if (linkname)

    {

      if (!realpath(linkname,rp_buff))

        my_load_path(rp_buff, linkname, NULL);

      rp_buff[FN_REFLEN-1]= '\0';

      strcpy(abs_linkname,rp_buff);

    }

    create_link= (linkname && strcmp(abs_linkname,filename));

  }

  if (!(MyFlags & MY_DELETE_OLD))

  {

    if (!access(filename,F_OK))

    {

      my_errno= errno= EEXIST;

      my_error(EE_CANTCREATEFILE, MYF(0), filename, EEXIST);

      return(-1);

    }

    if (create_link && !access(linkname,F_OK))

    {

      my_errno= errno= EEXIST;

      my_error(EE_CANTCREATEFILE, MYF(0), linkname, EEXIST);

      return(-1);

    }

  }

  if ((file=my_create(filename, createflags, access_flags, MyFlags)) >= 0)

  {

    if (create_link)

    {

      /* Delete old link/file */

      if (MyFlags & MY_DELETE_OLD)

	my_delete(linkname, MYF(0));

      /* Create link */

      if (symlink(filename,linkname))

      {

	/* Fail, remove everything we have done */

	tmp_errno=my_errno;

	my_close(file,MYF(0));

	my_delete(filename, MYF(0));

	file= -1;

	my_errno=tmp_errno;

      }

      else if (MyFlags & MY_SYNC_DIR)

        my_sync_dir_by_file(linkname, MyFlags);

    }

  }

  return(file);

}

/*

  If the file was a symlink, delete both symlink and the file which the

  symlink pointed to.

*/

int my_delete_with_symlink(const char *name, myf MyFlags)

{

  char link_name[FN_REFLEN];

  ssize_t sym_link_size= readlink(name,link_name,FN_REFLEN-1);

  int was_symlink= (!my_disable_symlinks && sym_link_size != -1);

  int result;

  if (!(result=my_delete(name, MyFlags)))

  {

    if (was_symlink)

    {

      link_name[sym_link_size]= '\0';

      result= my_delete(link_name, MyFlags);

    }

  }

  return(result);

}

/*

  If the file is a normal file, just rename it.

  If the file is a symlink:

   - Create a new file with the name 'to' that points at

     symlink_dir/basename(to)

   - Rename the symlinked file to symlink_dir/basename(to)

   - Delete 'from'

   If something goes wrong, restore everything.

*/

int my_rename_with_symlink(const char *from, const char *to, myf MyFlags)

{

#ifndef HAVE_READLINK

  return my_rename(from, to, MyFlags);

#else

  char link_name[FN_REFLEN], tmp_name[FN_REFLEN];

  int sym_link_size= -1;

  int was_symlink= (!my_disable_symlinks &&

                   (sym_link_size= readlink(from,link_name,FN_REFLEN-1)) != -1);

  int result=0;

  int name_is_different;

  if (!was_symlink)

    return(my_rename(from, to, MyFlags));

  else

    link_name[sym_link_size]= '\0';

  /* Change filename that symlink pointed to */

  strcpy(tmp_name, to);

  fn_same(tmp_name,link_name,1);		/* Copy dir */

  name_is_different= strcmp(link_name, tmp_name);

  if (name_is_different && !access(tmp_name, F_OK))

  {

    my_errno= EEXIST;

    if (MyFlags & MY_WME)

      my_error(EE_CANTCREATEFILE, MYF(0), tmp_name, EEXIST);

    return(1);

  }

  /* Create new symlink */

  if (symlink(tmp_name, to))

    return(1);

  else if (MyFlags & MY_SYNC_DIR)

    my_sync_dir_by_file(to, MyFlags);

  /*

    Rename symlinked file if the base name didn't change.

    This can happen if you use this function where 'from' and 'to' has

    the same basename and different directories.

   */

  if (name_is_different && my_rename(link_name, tmp_name, MyFlags))

  {

    int save_errno=my_errno;

    my_delete(to, MyFlags);			/* Remove created symlink */

    my_errno=save_errno;

    return(1);

  }

  /* Remove original symlink */

  if (my_delete(from, MyFlags))

  {

    int save_errno=my_errno;

    /* Remove created link */

    my_delete(to, MyFlags);

    /* Rename file back */

    if (strcmp(link_name, tmp_name))

      (void) my_rename(tmp_name, link_name, MyFlags);

    my_errno=save_errno;

    result= 1;

  }

  return(result);

#endif /* HAVE_READLINK */

}